Co-reporter:Faxing Wang;Zaichun Liu;Xinhai Yuan;Jun Mo;Chunyang Li;Lijun Fu;Yusong Zhu;Xiongwei Wu
Journal of Materials Chemistry A 2017 vol. 5(Issue 28) pp:14922-14929
Publication Date(Web):2017/07/18
DOI:10.1039/C7TA03920D
Electrochemical capacitors are playing increasing roles in our daily life but their low energy densities limit their wide applications. The appearance of Li-ion capacitors (LICs) is regarded as the beginning of a new era of increased energy densities in the field of electrochemical capacitors. However, it is a great challenge to find a suitable anode material with superior electrochemical performance. In addition, the intrinsic instability of the liquid electrolytes used in LICs can easily result in leakage of the electrolyte and causes a serious safety issue. Here, a quasi-solid-state LIC is fabricated by applying Li3VO4/carbon nanofibers as the anode and electrochemically-exfoliated graphene sheets as the cathode in a gel polymer electrolyte. It achieves an energy density of 110 W h kg−1 and a good cycling performance. Our results demonstrate that quasi-solid-state LICs provide a key system acting as a bridge between conventional Li-ion batteries and supercapacitors, while meeting the high safety demands of electronic devices.
Co-reporter:Xinhai Yuan;Bingwei Chen;Xiongwei Wu;Jun Mo;Zaichun Liu;Zhengyong Hu;Zhonghua Liu;Chunjiao Zhou;Haijun Yang
Chinese Journal of Chemistry 2017 Volume 35(Issue 1) pp:61-66
Publication Date(Web):2017/01/01
DOI:10.1002/cjoc.201600212
AbstractAn asymmetric supercapacitor (ASC) was assembled by using an activated carbon as positive electrode and WO3 nanowire as negative electrode, and its electrical performances were tested in voltage windows ranging from 0 to 1.5 V. A high specific capacitance of 51 F•g−1 could be achieved at the current density of 0.25 A•g−1. Moreover, the ASC displays a good cycling stability with 86% of capacitance retention after 800 cycles, its energy density can be up to 11.9 Wh•kg−1 at the power density of 210 W•kg−1, and remains 7.7 Wh•kg−1 at a power density of 1250 W• kg−1. The excellent electrical performance is perhaps due to the crystal orientation of (001) planes for the WO3 nanowire, which favors the rapid reaction between W(VI) and H+ cations. This aqueous asymmetric WO3//AC supercapacitor is promising for practical applications due to its easy preparation of WO3.
Co-reporter:Bingwei Chen;Yanfang Wang;Feng Yu;Yusong Zhu;Lixin Zhang
Chinese Journal of Chemistry 2017 Volume 35(Issue 1) pp:55-60
Publication Date(Web):2017/01/01
DOI:10.1002/cjoc.201600290
AbstractA porous carbon spheres@MnO2 composite is prepared and used as the electrosorption electrode. The MnO2 nanoparticles are evenly distributed on the porous carbon spheres. The as-prepared composite possesses high specific surface area of 258.6 m2•g−1. Its electrochemical evaluations confirm that the composite has high specific capacitance of 175 F•g−1 at a current density of 1 A•g−1 in 0.5 mol•L−1 NaCl aqueous solution, and shows good conductivity and excellent cycling performance. Electrosorption capacity for the porous carbon spheres@MnO2 composite is 6.28 mg•g−1. Moreover, the composite electrode exhibits excellent recyclability with an efficient regeneration process.
Co-reporter:Yi Zhang;Yusong Zhu;Lijun Fu;Jixing Meng;Nengfei Yu;Jing Wang
Chinese Journal of Chemistry 2017 Volume 35(Issue 1) pp:21-29
Publication Date(Web):2017/01/01
DOI:10.1002/cjoc.201600663
AbstractSilicon is very promising negative electrode materials for improving the energy density of lithium-ion batteries (LIBs) because of its high specific capacity, moderate potential, environmental friendliness, and low cost. However, the volume variation of Si negative electrodes is huge during lithiation/delithiation processes which results in pulverization, low cycling efficiency, and permanent capacity loss. In order to overcome this problem, tremendous efforts have been attempted. Among them the most successful strategy is to incorporate other components into silicon to form composite, especially the carbon medium. In this mini review, the recent progress on Si/C materials used as negative electrode of LIBs is summarized such as Si/amorphous carbon composite, Si/graphene composites, Si/carbon nanotubes or fibers composites. The fabrication, structure, electrochemical performances of different Si/C composites are discussed. In addition, some future directions are pointed out.
Co-reporter:Chun Wang, Faxing Wang, Zaichun Liu, Yujuan Zhao, Yong Liu, Qin Yue, Hongwei Zhu, Yonghui Deng, Yuping Wu, Dongyuan Zhao
Nano Energy 2017 Volume 41(Volume 41) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.nanoen.2017.10.025
•N-doped carbon hollow microspheres were synthesized by a facile interfacial sol-gel coating process.•Quasi-solid-state full sodium-ion capacitors with a Na+-conducting gel polymer electrolyte were demonstrated.•The devices exhibit a comprehensive and superior electrochemical performance.N-doped carbon hollow microspheres have been synthesized by a facile interfacial sol-gel coating process using resorcinol/formaldehyde as the carbon precursor and ethylenediamine (EDA) as both the base catalyst and nitrogen precursor. They possessed uniform size of ~ 120 nm in diameter with porous shells as thin as ~ 10 nm. The BET specific surface area and pore volume were measured to be 267 m2 g−1 and 1.2 cm3 g−1, respectively. The nitrogen doping of 8.23 wt% in carbon matrix could be achieved without sacrificing the hollow spherical morphology. Density functional theory (DFT) calculation results clearly reveal that N-doping could significantly change the interaction sites and enhance the adsorption of PF6- ions towards carbon framework. Quasi-solid-state full sodium-ion capacitors employing the nanoporous disordered carbon nanoparticles and N-doped carbon hollow microspheres as the battery-type negative and supercapacitor-type positive electrodes with a Na+-conducting gel polymer electrolyte were demonstrated. The devices exhibit a comprehensive and superior electrochemical performance in terms of ultrahigh operating voltage of 4.4 V, high energy density of 157 W h kg−1 at 620 W kg−1, and prolonged cycling stability over 1000 cycles with ~ 70% of capacitance retention. Such outstanding performances suggest that the quasi-solid-state full sodium-ion capacitors could be potential safe and flexible electrochemical energy storage devices in the near future.Download high-res image (162KB)Download full-size image
Co-reporter:Yusong Zhu, Yaqiong Yang, Lijun Fu, Yuping Wu
Electrochimica Acta 2017 Volume 224(Volume 224) pp:
Publication Date(Web):10 January 2017
DOI:10.1016/j.electacta.2016.12.030
•A porous composite gel electrolyte reinforced by PP nonwoven for SIBs is reported.•Ionic conductivity of the GPE at r.t. is 4 times higher than commercial separator.•The stress of the GPE arrives almost the same level with Celgard 2730 separator.•The gel polymer electrolyte shows good electrolyte retention even at 110 °C.•The electrochemical reversibility for Na4Mn9O8 has been confirmed by using the GPE.A porous composite membrane with P(VDF-HFP) as host and nonwoven as reinforcement has been successfully prepared and reported in this paper. The tensile strength of the composite is very close to that of Celgard 2730 separator in both wet and dry state. The Na+ ionic conductivity of the given gel-type composite membrane (0.82 mS cm−1) absorbed NaClO4 organic liquid electrolyte at room temperature has found to be four times higher than that of the commercial separator saturated with the same electrolyte (0.16 mS cm−1). It has also showed enhanced transference number of Na+ ions and good electrolyte retention even at 110 °C. The electrochemical reversibility for Na4Mn9O8 cathode has been confirmed by cyclic voltammetry by using the aforementioned gel polymer electrolyte (GPE). The porous composite GPE exhibits great application prospect for sodium ion batteries with high energy density.
Co-reporter:Bingwei Chen;Yanfang Wang;Chunyang Li;Lijun Fu;Xiang Liu;Yusong Zhu;Lixin Zhang
RSC Advances (2011-Present) 2017 vol. 7(Issue 40) pp:25019-25024
Publication Date(Web):2017/05/05
DOI:10.1039/C7RA01954H
It has been a challenge to achieve a good capacitive performance for Cr-based oxides, and only few studies have been reported on these oxides. Herein, a composite of chromium oxide (Cr2O3) and multi-walled carbon nanotubes (MWCNTs) was prepared by a simple hydrothermal procedure followed by thermal decomposition. The Cr2O3 nanoparticles were evenly decorated on the surface of MWCNTs. The prepared Cr2O3/MWCNTs composite exhibited superior electrochemical performance in a 1 M KOH electrolyte, i.e., 257 F g−1 at the current density of 0.25 A g−1, and the capacity fade was only 12% after 3000 cycles. In addition, the Cr2O3/MWCNTs//AC asymmetric capacitor has high energy density (15.2 W h kg−1 at 266 W kg−1). The abovementioned results for the first time indicate the potential application of Cr2O3 as an electrode material for supercapacitors.
Co-reporter:Bingwei Chen;Yanfang Wang;Chunyang Li;Lijun Fu;Xiang Liu;Yusong Zhu;Lixin Zhang
RSC Advances (2011-Present) 2017 vol. 7(Issue 40) pp:25019-25024
Publication Date(Web):2017/05/05
DOI:10.1039/C7RA01954H
It has been a challenge to achieve a good capacitive performance for Cr-based oxides, and only few studies have been reported on these oxides. Herein, a composite of chromium oxide (Cr2O3) and multi-walled carbon nanotubes (MWCNTs) was prepared by a simple hydrothermal procedure followed by thermal decomposition. The Cr2O3 nanoparticles were evenly decorated on the surface of MWCNTs. The prepared Cr2O3/MWCNTs composite exhibited superior electrochemical performance in a 1 M KOH electrolyte, i.e., 257 F g−1 at the current density of 0.25 A g−1, and the capacity fade was only 12% after 3000 cycles. In addition, the Cr2O3/MWCNTs//AC asymmetric capacitor has high energy density (15.2 W h kg−1 at 266 W kg−1). The abovementioned results for the first time indicate the potential application of Cr2O3 as an electrode material for supercapacitors.
Co-reporter:Xiongwei Wu;Xinhai Yuan;Jingang Yu;Jun Liu;Faxing Wang;Lijun Fu;Wenxin Zhou;Yusong Zhu;Qingming Zhou
Nanoscale (2009-Present) 2017 vol. 9(Issue 31) pp:11004-11011
Publication Date(Web):2017/08/10
DOI:10.1039/C7NR03602G
Anode materials with high capacity for aqueous rechargeable lithium batteries (ARLBs) are very rarely reported. Here we found that a dual core–shell structured MWCNTs@S@PPy nanocomposite prepared by us shows excellent electrochemical performance. Its initial discharge capacity in a saturated LiAc aqueous electrolyte is very high, which is up to 481 mA h g−1 based on the weight of the composite and 879 mA h g−1 based on the sulfur content. It shows excellent rate capability. When nanotube LiMn2O4 is used as a cathode, the assembled ARLB can deliver an energy density of 110 Wh kg−1 based on two electrodes and show excellent cycling. These results show great promise for the practical application of ARLBs.
Co-reporter:Yanfang Wang;Bingwei Chen;Zheng Chang;Xiaowei Wang;Faxing Wang;Lixin Zhang;Yusong Zhu;Lijun Fu
Journal of Materials Chemistry A 2017 vol. 5(Issue 19) pp:8981-8988
Publication Date(Web):2017/05/16
DOI:10.1039/C7TA01500C
Metal sulfides (MSs) should be feasible candidates for hybrid electrochemical capacitors (HECs) due to their high theoretical specific capacitances. However, their performances are largely hampered by sluggish ion/electron transport kinetics and fast capacitance fading. Here, we provide a new approach to fabricate high-performance dual-structural MSs for long-life electrochemical energy storage devices. With robust, graphitic and nitrogen-doped porous carbon shells and highly conductive reduced graphene oxide (RGO) substrates, our cobalt sulfide-based composite shows 99.7% capacitance retention after 4000 cycles. We also present a sandwich-like carbon electrode with ultrahigh specific capacitance and excellent cycling stability. As a result, a quasi-solid-state HEC comprising the above-mentioned electrodes and a PVA–PAA membrane is fabricated. Its electrochemical performance is superior to those formerly reported for MSs, and our results for the first time provide a solid base for the application of MSs in HECs.
Co-reporter:Lili Liu;Haipeng Guo;Yuyang Hou;Jun Wang;Lijun Fu;Jun Chen;Huakun Liu;Jiazhao Wang
Journal of Materials Chemistry A 2017 vol. 5(Issue 28) pp:14673-14681
Publication Date(Web):2017/07/18
DOI:10.1039/C7TA03553E
Herein, a three-dimensional (3D) hierarchical porous Co3O4 nanotube (Co3O4 HPNT) network was prepared using a polypyrrole nanofiber (PPyNF) as a sacrificial template. When employed as a cathode for lithium–oxygen batteries, the 3D Co3O4 HPNT network demonstrated superior bifunctional electrocatalytic activities towards both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), with a relatively low charge overpotential of 99 mV and a high discharge/charge capacity of 4164/4299 mA h g−1. High-resolution scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy measurements on Co3O4 HPNT-based cathode after discharge/recharge showed reversible formation and decomposition of Li2O2. This superior performance is ascribed to the 3D web-like porous tubular structure, which facilitates rapid oxygen flow, provides enough void volume for insoluble Li2O2 deposition, and increases the catalytic utilization of Co3O4. Moreover, the hierarchical porous structure with meso-/nanopores on the walls of the Co3O4 nanotubes facilitates O2 diffusion, electrolyte penetration, and mass transport of all the reactants.
Co-reporter:Faxing Wang;Xiongwei Wu;Xinhai Yuan;Zaichun Liu;Yi Zhang;Lijun Fu;Yusong Zhu;Qingming Zhou;Wei Huang
Chemical Society Reviews 2017 vol. 46(Issue 22) pp:6816-6854
Publication Date(Web):2017/11/13
DOI:10.1039/C7CS00205J
Notably, many significant breakthroughs for a new generation of supercapacitors have been reported in recent years, related to theoretical understanding, material synthesis and device designs. Herein, we summarize the state-of-the-art progress toward mechanisms, new materials, and novel device designs for supercapacitors. Firstly, fundamental understanding of the mechanism is mainly focused on the relationship between the structural properties of electrode materials and their electrochemical performances based on some in situ characterization techniques and simulations. Secondly, some emerging electrode materials are discussed, including metal–organic frameworks (MOFs), covalent organic frameworks (COFs), MXenes, metal nitrides, black phosphorus, LaMnO3, and RbAg4I5/graphite. Thirdly, the device innovations for the next generation of supercapacitors are provided successively, mainly emphasizing flow supercapacitors, alternating current (AC) line-filtering supercapacitors, redox electrolyte enhanced supercapacitors, metal ion hybrid supercapacitors, micro-supercapacitors (fiber, plane and three-dimensional) and multifunctional supercapacitors including electrochromic supercapacitors, self-healing supercapacitors, piezoelectric supercapacitors, shape-memory supercapacitors, thermal self-protective supercapacitors, thermal self-charging supercapacitors, and photo self-charging supercapacitors. Finally, the future developments and key technical challenges are highlighted regarding further research in this thriving field.
Co-reporter:Zhi-Hang Wang;Jia-Ying Yang;Xiong-Wei Wu
Journal of Nanoparticle Research 2017 Volume 19( Issue 2) pp:
Publication Date(Web):2017/02/01
DOI:10.1007/s11051-017-3778-x
In this work, a novel activated carbon containing graphene composite was developed using a fast, simple, and green ultrasonic-assisted method. Graphene is more likely a framework which provides support for activated carbon (AC) particles to form hierarchical microstructure of carbon composite. Scanning electron microscope (SEM), transmission electron microscope (TEM), Brunauer–Emmett–Teller (BET) surface area measurement, thermogravimetric analysis (TGA), Raman spectra analysis, XRD, and XPS were used to analyze the morphology and surface structure of the composite. The electrochemical properties of the supercapacitor electrode based on the as-prepared carbon composite were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), charge/discharge, and cycling performance measurements. It exhibited better electrochemical performance including higher specific capacitance (284 F g−1 at a current density of 0.5 A g−1), better rate behavior (70.7% retention), and more stable cycling performance (no capacitance fading even after 2000 cycles). It is easier for us to find that the composite produced by our method was superior to pristine AC in terms of electrochemical performance due to the unique conductive network between graphene and AC.
Co-reporter:Xiaowei Wang;Faxing Wang;Liying Wang;Minxia Li;Yanfang Wang;Bingwei Chen;Yusong Zhu;Lijun Fu;Liusheng Zha;Lixin Zhang;Wei Huang
Advanced Materials 2016 Volume 28( Issue 24) pp:4904-4911
Publication Date(Web):
DOI:10.1002/adma.201505370
Co-reporter:Faxing Wang, Zaichun Liu, Xiaowei Wang, Xinhai Yuan, Xiongwei Wu, Yusong Zhu, Lijun Fu and Yuping Wu
Journal of Materials Chemistry A 2016 vol. 4(Issue 14) pp:5115-5123
Publication Date(Web):01 Mar 2016
DOI:10.1039/C6TA01398H
Electrochemical capacitors are becoming promising energy conversion/storage and power output devices. However, high cost and low energy density are two serious disadvantages. By integrating the advantages of Li-/Na-ion batteries and electrochemical capacitors, Li-/Na-ion capacitors have been explored recently. Al is very cheap and is the most abundant metal element on the earth. There are few reports on Al-ion capacitors due to the challenges in finding a suitable anode with large capacitance and good rate performance. Here, the feasibility of assembling an Al-ion capacitor with good electrochemical performance is demonstrated. The Al-ion capacitor is assembled by using a composite of MoO3 nanotubes coated by a conductive polypyrrole (PPy@MoO3) as an anode, which functions via a redox intercalation/deintercalation of Al3+ ions in aqueous solution. It delivers a capacitance of 693 F g−1, about 3 times higher than that of electrode materials for sodium-ion capacitors in aqueous solution. Combined with an activated carbon (AC) cathode, the Al-ion capacitor presents an energy density of 30 W h kg−1 and an excellent cycling life with 93% capacitance retention after 1800 cycles. This finding provides another energy storage device with low cost and promotes the application of capacitors.
Co-reporter:Faxing Wang, Feng Yu, Xiaowei Wang, Zheng Chang, Lijun Fu, Yusong Zhu, Zubiao Wen, Yuping Wu, and Wei Huang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 14) pp:9022
Publication Date(Web):December 30, 2015
DOI:10.1021/acsami.5b06142
Developing rechargeable batteries with low cost is critically needed for the application in large-scale stationary energy storage systems. Here, an aqueous rechargeable zinc//aluminum ion battery is reported on the basis of zinc as the negative electrode and ultrathin graphite nanosheets as the positive electrode in an aqueous Al2(SO4)3/Zn(CHCOO)2 electrolyte. The positive electrode material was prepared through a simple electrochemically expanded method in aqueous solution. The cost for the aqueous electrolyte together with the Zn negative electrode is low, and their raw materials are abundant. The average working voltage of this aqueous rechargeable battery is 1.0 V, which is higher than those of most rechargeable Al ion batteries in an ionic liquid electrolyte. It could also be rapidly charged within 2 min while maintaining a high capacity. Moreover, its cycling behavior is also very good, with capacity retention of nearly 94% after 200 cycles.Keywords: aqueous rechargeable battery; graphite; intercalation; nanosheet; rapid charge; Zn negative electrode;
Co-reporter:Yu Liu, Zubiao Wen, Xiongwei Wu, Xiaowei Wang, Yuping Wu and Rudolf Holze
Chemical Communications 2016 vol. 52(Issue 48) pp:7620-7620
Publication Date(Web):31 May 2016
DOI:10.1039/C6CC90241C
Correction for ‘An acid-free rechargeable battery based on PbSO4 and spinel LiMn2O4’ by Yu Liu et al., Chem. Commun., 2014, 50, 13714–13717.
Co-reporter:Yanfang Wang, Bingwei Chen, Yi Zhang, Lijun Fu, Yusong Zhu, Lixin Zhang, Yuping Wu
Electrochimica Acta 2016 Volume 213() pp:260-269
Publication Date(Web):20 September 2016
DOI:10.1016/j.electacta.2016.07.019
•Necklace architectures with ZIF-8 nanocrystals strung on MWCNTs are obtained.•“Necklace” derived carbons exhibit hierarchical micro-mesoporous structures.•The carbon exhibits excellent rate and cycling capability.•The capacitance retention after 10000 cycles at 10 A·g−1 is 99.7%.•The synergistic interactions contribute to the excellent performances.Carbon materials from zeolitic imidazolate framework (ZIF) present poor electrochemical performance as electrode materials for supercapacitors. In this work, well-intergrown ZIF nanocystals are strung on MWCNTs to form necklace architecture. After carbonization and chemical etching, porous carbons with necklace architecture and proper hierarchical micro-mesoporous structure were obtained. It exhibits excellent electrochemical performance as electrode material for supercapacitor in 1 M H2SO4 solution such as high specific capacitance up to 326 F·g−1 at 1 A·g−1, good rate capability and excellent cycling stability of 99.7% capacitance retention after 10000 cycles. The main reasons are due to the increased surface area, the improved electrical conductivity, and the combination of micro- and meso-porous structure. This provides another promising way to design porous carbons from ZIF materials for supercapacitors.
Co-reporter:Bingwei Chen, Yanfang Wang, Zheng Chang, Xiaowei Wang, Minxia Li, Xiang Liu, Lixin Zhang and Yuping Wu
RSC Advances 2016 vol. 6(Issue 8) pp:6730-6736
Publication Date(Web):07 Jan 2016
DOI:10.1039/C5RA26210K
The morphology and structure of the prepared MnO2/MWCNTs (multi-walled carbon nanotubes) composite are characterized by XRD, SEM, TEM, and N2 sorption analysis. The electrochemical performance of the composite is studied by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge evaluation. The composite has a specific capacitance of 144 F g−1 at the current density of 1 A g−1. It has higher conductivity which is affirmed by electrochemical impedance spectroscopy (EIS). The capacitive deionization (CDI) test was conducted in a bath mode apparatus by assembling a capacitor. The capacitor made from MnO2/MWCNTs composite shows a higher desalination capacity of (6.65 mg g−1) in NaCl aqueous solution, higher than that made from the virginal MnO2 (1.60 mg g−1) and those of the formerly reported. Furthermore, the MnO2/MWCNTs composite electrode shows excellent recyclability with an efficient and rapid regeneration process.
Co-reporter:Lili Liu;Yuyang Hou;Jun Wang;Jun Chen;Hua-Kun Liu;Jiazhao Wang
Advanced Materials Interfaces 2016 Volume 3( Issue 13) pp:
Publication Date(Web):
DOI:10.1002/admi.201600030
Co3O4 nanocrystals strongly coupled with a 3D structured polypyrrole (PPy) nanoweb via a rapid hydrothermal method are presented for the first time as a bifunctional synergetic catalyst for Li-O2 batteries. The obtained Co3O4/PPy hybrid material shows improved oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performances, specifically, a larger discharge/charge capacity of 3585/2784 mAh g−1, respectively, at a current density of 100 mA g−1, and lower recharge overpotential, as well as better rate capability compared to pristine PPy cathode. Rotating disk electrode measurements and electrocatalytic testing, as well as characterization after cycling, shows that the pristine PPy can act as a good support and good ORR catalyst, but only as a poor OER catalyst, with Li2O2 and Li2CO3 as its main discharge products, while the nanofibrous Co3O4/PPy hybrid can catalyze reversible Li2O2 formation and decomposition in Li-O2 batteries. The improved performance is attributed to the synergistic effects from the PPy matrix with its highly conductive 3D nanoweb structure and the Co3O4 nanoparticles with intrinsically high catalytic activity.
Co-reporter:Faxing Wang, Xiaowei Wang, Zheng Chang, Yusong Zhu, Lijun Fu, Xiang Liu and Yuping Wu
Nanoscale Horizons 2016 vol. 1(Issue 4) pp:272-289
Publication Date(Web):18 Feb 2016
DOI:10.1039/C5NH00116A
In recent years, the design and morphological control of crystals with tailored facets have become hot spots in the field of electrochemical energy storage devices. For electrode materials, morphologies play important roles in their activities because their shapes determine how many facets of specific orientation are exposed and therefore available for surface reactions. This review focuses on the strategies for crystal facet control and the unusual electrochemical properties of electrode materials bound by tailored facets. Here, electrode materials with tailored facets include transition metal oxides such as SnO2, Co3O4, NiO, Cu2O, and MnO2, elementary substances such as Si and Au, and intercalation compounds such as Li4Ti5O12, LiCoO2, LiMn2O4, LiFePO4, and Na0.7MnO2 for various applications of Li-ion batteries, aqueous rechargeable lithium batteries, Na-ion batteries, Li–O2 batteries and supercapacitors. How these electrode materials with tailored facets affect their electrochemical properties is discussed. Finally, research opportunities as well as the challenges in this emerging research frontier are highlighted.
Co-reporter:Y.S. Zhu, L.L. Li, C.Y. Li, L. Zhou, Y.P. Wu
Solid State Ionics 2016 Volume 289() pp:113-117
Publication Date(Web):June 2016
DOI:10.1016/j.ssi.2016.02.021
•A Na+-conducting glass–ceramic containing crystalline NASICON phase was successfully prepared.•Al cation enters the structure of NASICON by replacing Ge4 + ions.•The highest sodium ionic conductivity of the glass–ceramic is up to 9.27 × 10− 5 S cm− 1 at 140 °C.•The reasons for the increase of the ionic conductivity in the glass–ceramic are discussed.Sodium-ion conducting glass–ceramics composed of Na1 + xAlxGe2 − xP3O12 (x = 0.5) crystalline conducting phase were successfully prepared by heat-treating the parent glass at different temperature and time, and were characterized with DSC, XRD, CV, SEM and alternative current impedance. The relationship between the ionic conductivity and crystallization conditions (time and temperature) of the sodium aluminum germanium phosphate (NAGP) glass–ceramic was investigated. Results show that the NASICON phases containing Al3 + in all these glass–ceramics are isomorphous with NaGe2P3O12 and stable against sodium metal. The highest total conductivity of the glass–ceramic material, 9.27 × 10− 5 S cm− 1 at 140 °C, is obtained by highly crystallizing the glass at 750 °C for 12 h. The reasons for the enhancement of the ionic conductivity in the glass–ceramics are discussed in view of the dependence of microstructure morphology on the heating condition. It could be attributed to its good crystallization of the conductive phase NAGP, uniform grain size and possible optimizing conductive pathway of Na+ ions.
Co-reporter:Faxing Wang;Xiaowei Wang;Zheng Chang;Xiongwei Wu;Xiang Liu;Lijun Fu;Yusong Zhu;Wei Huang
Advanced Materials 2015 Volume 27( Issue 43) pp:6962-6968
Publication Date(Web):
DOI:10.1002/adma.201503097
Co-reporter:Jiaxin Zheng, Yuyang Hou, Yandong Duan, Xiaohe Song, Yi Wei, Tongchao Liu, Jiangtao Hu, Hua Guo, Zengqing Zhuo, Lili Liu, Zheng Chang, Xiaowei Wang, Danylo Zherebetskyy, Yanyan Fang, Yuan Lin, Kang Xu, Lin-Wang Wang, Yuping Wu, and Feng Pan
Nano Letters 2015 Volume 15(Issue 9) pp:6102-6109
Publication Date(Web):August 25, 2015
DOI:10.1021/acs.nanolett.5b02379
LiFePO4 has long been held as one of the most promising battery cathode for its high energy storage capacity. Meanwhile, although extensive studies have been conducted on the interfacial chemistries in Li-ion batteries,1−3 little is known on the atomic level about the solid–liquid interface of LiFePO4/electrolyte. Here, we report battery cathode consisted with nanosized LiFePO4 particles in aqueous electrolyte with an high charging and discharging rate of 600 C (3600/600 = 6 s charge time, 1 C = 170 mAh g–1) reaching 72 mAh g–1 energy storage (42% of the theoretical capacity). By contrast, the accessible capacity sharply decreases to 20 mAh g–1 at 200 C in organic electrolyte. After a comprehensive electrochemistry tests and ab initio calculations of the LiFePO4–H2O and LiFePO4–EC (ethylene carbonate) systems, we identified the transient formation of a Janus hydrated interface in the LiFePO4–H2O system, where the truncated symmetry of solid LiFePO4 surface is compensated by the chemisorbed H2O molecules, forming a half-solid (LiFePO4) and half-liquid (H2O) amphiphilic coordination environment that eases the Li desolvation process near the surface, which makes a fast Li-ion transport across the solid/liquid interfaces possible.
Co-reporter:Lei Zhu, Zheng Chang, Yanfang Wang, Bingwei Chen, Yusong Zhu, Weiping Tang and Yuping Wu
Journal of Materials Chemistry A 2015 vol. 3(Issue 44) pp:22066-22072
Publication Date(Web):21 Sep 2015
DOI:10.1039/C5TA05556C
Supercapacitors display high power density and long cycling life that are particularly amenable for use in the field of energy storage. However, the cost is a big issue for practical application. Here, cheap Fe2O3 spindles from a rich natural resource are used as the positive electrode. Through the twining of MnO2 nanoflakes via a simple and cost-effective hydrothermal method, a unique structure of a core–shell MnO2@Fe2O3 nanospindle has been prepared. The electrochemical performance of the nanospindles including capacitance and cycling life is markedly improved compared with the pristine Fe2O3 spindles. Its specific capacitance is up to 159 F g−1 at a current density of 0.1 A g−1 and especially, the capacitance retention is 97.4% after 5000 cycles in a 0.5 mol L−1 K2SO4 neutral aqueous electrolyte. Combined with activated carbon as the negative electrode, the energy density can be up to 43.8 W h kg−1 on the basis of the weights of the two electrodes. These results reveal that the core–shell MnO2@Fe2O3 nanospindles are a promising positive electrode for practical supercapacitors.
Co-reporter:Lei Zhu, Yang Liu, Wenyi Wu, Xiongwei Wu, Weiping Tang and Yuping Wu
Journal of Materials Chemistry A 2015 vol. 3(Issue 29) pp:15156-15162
Publication Date(Web):11 Jun 2015
DOI:10.1039/C5TA02529J
LiNi0.8Co0.15Al0.05O2 is considered as an alternative to the commercial LiCoO2 positive electrode material for lithium ion batteries because of its excellent cycling performance. However, its capacity fading and potential safety hazard still need to be improved. In this study, fluorination has been introduced for the first time to modify the surface of LiNi0.8Co0.15Al0.05O2 by a one-step facile and dry method. The crystalline structure, morphology, surface information and electrochemical performance were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectronic spectroscopy and electrochemical tests. The surface-fluorinated LiNi0.8Co0.15Al0.05O2 exhibits a reversible capacitance up to 220.5 mA h g−1 at 0.1 C, good rate capability, and an excellent long-term cycling stability with 93.6% capacity retention after 80 cycles at 0.1 C, which is much better than that of the pristine commercial LiNi0.8Co0.15Al0.05O2. The main reason is that metal-fluorine (M–F) bond partially replaces the metal–oxygen (M–O) bond at the surface, enhancing the entire bond energy as well as the structure stability. In addition, the interfacial conductivity between the electrolyte and the positive electrode has been increased, leading to a faster kinetic process. These results show that fluorinated LiNi0.8Co0.15Al0.05O2 is a promising positive electrode material for high performance lithium ion batteries.
Co-reporter:Xiaowei Wang, Minxia Li, Yanfang Wang, Bingwei Chen, Yusong Zhu and Yuping Wu
Journal of Materials Chemistry A 2015 vol. 3(Issue 16) pp:8280-8283
Publication Date(Web):19 Mar 2015
DOI:10.1039/C5TA01947H
A Zn–NiO rechargeable battery comprising a NiO nanosheet anchored to CNTs as the positive electrode, a zinc plate as the negative one and an alkaline solution of 1 M KOH and 10 mM Zn(Ac)2 as the electrolyte is reported. It delivers a voltage of ∼1.75 V and a high energy density of 228 W h kg−1 (based on the mass of the positive electrode composite and zinc) with good cycling. It has great promise for practical energy storage applications.
Co-reporter:Faxing Wang, Zheng Chang, Xiaowei Wang, Yanfang Wang, Binwei Chen, Yusong Zhu and Yuping Wu
Journal of Materials Chemistry A 2015 vol. 3(Issue 9) pp:4840-4845
Publication Date(Web):19 Jan 2015
DOI:10.1039/C4TA06309K
The core–shell structure of Co3O4@Li2MnO3 was prepared by a facile hydrothermal method following heat treatment at 300 °C. The outer shell is porous and makes the diffusion of Li+ ions to the inner shell easier. The synergetic effect between the core and shell shows that the Co3O4 shell in the composite serves as a host to react with lithium oxide removed from the Li2MnO3 core during the initial charging process, which eliminates the huge irreversible capacity loss of Li2MnO3. As the cathode material for lithium ion batteries, the composite exhibits an attractive discharge capacity of 178 mA h g−1 with little irreversible capacity loss in the voltage range of 2.0–4.8 V. Its cycling performance is stable without any drastic capacity fading when cycling in the high voltage range of 2.0–4.6 V.
Co-reporter:Xiaowei Wang, Minxia Li, Zheng Chang, Yaqiong Yang, Yuping Wu, and Xiang Liu
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 4) pp:2280
Publication Date(Web):January 15, 2015
DOI:10.1021/am5062272
Using a simple hydrothermal procedure, cobalt oxide (Co3O4) with preferred orientation along (220) planes is in situ prepared and coated on MWCNT. The prepared Co3O4@MWCNT nanocable shows superior electrochemical performance as cathode material for aqueous supercapacitors in 0.5 M KOH solution. Its redox peaks retain the well-defined shapes even when the scan rate increases to 200 mV/s. Its specific capacitance is high, 590 F/g at 15 A/g and 510 F/g even at 100 A/g within the potential range from −0.2 to 0.58 V (vs SCE). There is no capacitance fading after 2000 full cycles. This excellent performance is superior to the pristine and the reported Co3O4, which is ascribed to the unique nanocable structure with orientation.Keywords: cathode; Co3O4@MWCNT; nanocable; rate performance; supercapacitor
Co-reporter:M.X. Li, X.W. Wang, Y.Q. Yang, Z. Chang, Y.P. Wu, R. Holze
Journal of Membrane Science 2015 Volume 476() pp:112-118
Publication Date(Web):15 February 2015
DOI:10.1016/j.memsci.2014.10.056
•A renewable and environment friendly cellulose is used to prepare gel polymer electrolyte.•The preparation process is simple.•The prepared polymer membrane is nonporous and dense instead of porous.•The prepared gel polymer electrolyte shows good electrochemical performance.A dense instead of porous gel polymer electrolyte for lithium ion batteries is reported for the first time. Its host is a renewable and environment friendly polymer, hydroxyethyl cellulose (HEC). The preparation of HEC membrane is very simple. The membrane is stable up to 280 °C, much higher than the melting points of those commercial separators based on polyolefin. The evaporation temperature of the organic electrolyte in the prepared gel polymer electrolytes is up to 75 °C. In addition, the gel polymer electrolyte shows good electrochemical performance including high ionic conductivity at room temperature, and a high lithium ion transference number. When tested as separator and electrolyte, a LiFePO4 positive electrode displays satisfactory electrochemical properties including high discharge capacity and stable cycling. These results indicate a very promising direction for a low cost and renewable gel polymer electrolyte for lithium ion batteries.A dense instead of a porous gel polymer electrolyte with high transference number of Li+ ions and good safety.
Co-reporter:J. Liu, Z.A. Wang, X.W. Wu, X.H. Yuan, J.P. Hu, Q.M. Zhou, Z.H. Liu, Y.P. Wu
Journal of Power Sources 2015 Volume 299() pp:301-308
Publication Date(Web):20 December 2015
DOI:10.1016/j.jpowsour.2015.09.004
•A porous carbon (PC) is for the first time prepared from bio-friendly shaddock peel.•It can act as good catalyst for vanadium redox flow battery (VRB).•The prepared VRB presents good electrochemical performance.Functional porous carbon (PC) derived from bio-friendly shaddock peel has been firstly explored as catalyst for vanadium redox flow battery (VRB). The prepared PC is micro-mesoporous with high BET surface area of 882.7 m2 g−1, has some surface oxygen-containing functional groups, and is doped with N and P heteroatoms. These three factors greatly favor the electrochemical reactions of VO2+/+VO2VO2+ on the PC modified glass carbon (PC-GC). Compared with the naked GC and graphite modified GC, the PC-GC presents a lower peak separation (66 mV), higher anodic current density (17.1 mA cm−2) and cathodic current density (15.0 mA cm−2). The VRB using PC modified graphite felt (GF) as positive electrode demonstrates an enhanced voltage efficiency of 82.7% at the current density of 60 mA cm−2, and a better rate performance than that from the virginal GF.
Co-reporter:Faxing Wang, Shiying Xiao, Minxia Li, Xiaowei Wang, Yusong Zhu, Yuping Wu, Akihiko Shirakawa, Jun Peng
Journal of Power Sources 2015 Volume 287() pp:416-421
Publication Date(Web):1 August 2015
DOI:10.1016/j.jpowsour.2015.04.034
•A core-shell structured FePO4@Li2MnO3 nanocomposite is synthesized.•It eliminates the large irreversible capacity for the Li-rich cathode materials.•Its initial Coulomb efficiency can be 100%.•Its cycling performance is also stable even in the high voltage range of 2.0–4.8 V.•It is free of Co- and Ni, different from other Li-rich Li2MnO3 cathode materials.A core-shell nanocomposite of Li2MnO3 is synthesized by coating FePO4 nanoparticles on the surface of our prepared Li2MnO3 nanoplate. This core-shell structured nanocomposite can eliminate the large irreversible capacity for the Li-rich materials. The FePO4 on the surface of Li2MnO3 can also serve as a host for Li ions that deintercalate from Li2MnO3 during the initial charging process and the initial Coulomb efficiency can be 100%. The composite as the cathode material for lithium ion batteries exhibits an attractive reversible capacity of 180 mAh g−1. Its cycling performance is also stable without any evident capacity fading, even when cycling in the high voltage range of 2.0–4.8 V vs. Li+/Li. This nanocomposite is free of Co- and Ni, different from other Li-rich Li2MnO3 based cathode materials, and shows great attraction for applications of low cost cathode materials for lithium ion batteries.Its irreversible capacity can be down to 0, and cycling is also very good.
Co-reporter:Y.S. Zhu, L. Li, L.J. Fu, Y.P. Wu
International Journal of Hydrogen Energy 2015 Volume 40(Issue 41) pp:14290-14296
Publication Date(Web):2 November 2015
DOI:10.1016/j.ijhydene.2015.04.074
•A FTO coated with CdS is prepared with simple chemical bath deposition.•It acts as photoanode to split formic acid to produce hydrogen.•The splitting voltage to produce hydrogen is extremely lower even with visible light.•The energy conversion efficiency can be 1.2%.The photoelectrochemical (PEC) behaviour of cadmium sulphide/fluorine-doped tin oxide conductive glass (CdS/FTO) photoanode that prepared by simple chemical bath deposition to split formic acid and produce hydrogen was tested. Compared to splitting water or utilizing FTO as anode, the splitting voltage to produce hydrogen on CdS/FTO anode is extremely low when the PEC reaction is carried out in formic acid solution irradiated with visible light. Furthermore, the energy conversion efficiency can be 1.2%. This may offer a new route for hydrogen production and treatment of formic acid waste water.
Co-reporter:Jun Liu;Junping Hu;Qi Deng;Jun Mo;Hao Xie;Zaichun Liu;Yuanfu Xiong;Xiongwei Wu
Israel Journal of Chemistry 2015 Volume 55( Issue 5) pp:521-536
Publication Date(Web):
DOI:10.1002/ijch.201400155
Abstract
The depletion of fossil fuels and environmental pollution provide an increasing requirement for rechargeable batteries with high energy densities, high efficiency, and excellent cycling performance. Aqueous rechargeable batteries (ARBs), with the merits of safety, low-cost, super-fast charge-discharge ability, and environmental friendliness, are one of the most competitive technologies for large-scale energy systems. Recently, extensive efforts have been dedicated to enhancing their electrochemical performance, and great breakthroughs have been achieved, especially for aqueous rechargeable lithium batteries (ARLBs), including three generations of ARLBs, aqueous rechargeable sodium batteries (ARSBs), and redox flow batteries (RFBs). Herein, the latest advances on their critical components are reviewed, and challenges and further directions are also pointed out.
Co-reporter:Lei Zhu
The Journal of Physical Chemistry C 2015 Volume 119(Issue 13) pp:7069-7075
Publication Date(Web):February 27, 2015
DOI:10.1021/acs.jpcc.5b01498
A hydrothermal-oxidation two-step method has been employed to fabricate a composite of CoOOH nanoplates with conducting multiwalled carbon nanotubes (MWCNTs), which present excellent electrochemical performance as a cathode material for a supercapacitor. The conductive nanostructure network of MWCNTs not only provides effective surface area for the contact between the electrode material and the electrolyte but also shortens the diffusion distances for ions and electrons and buffers the volume change, resulting in higher capacitance, faster redox reaction kinetics, and outstanding cycling stability. The maximum specific capacitance of the composite can achieve 270 F g–1 at a current density of 1 A g–1 in 0.5 mol L–1 KOH aqueous solution. It also exhibits good rate capability with a capacitance of 169 F g–1 even at a high current density of 10 A g–1 and outstanding long-term cycling stability, almost 100% retention of its initial capacitance after 10 000 full cycles. In contrast, the virginal CoOOH shows a capacitance of only 124 and 100 F g–1 at 1 and 10 A g–1, respectively, and its capacitance retention is only 79.4% after 10 000 full cycles. These results, for the first time, indicate that the composite of CoOOH nanoplates with MWCNTs is a promising cathode material for high-performance aqueous supercapacitors.
Co-reporter:Faxing Wang;Yu Liu;Xiaowei Wang;Zheng Chang; Yuping Wu; Rudolf Holze
ChemElectroChem 2015 Volume 2( Issue 7) pp:1024-1030
Publication Date(Web):
DOI:10.1002/celc.201500033
Abstract
A composite of rod-shaped LiNi1/3Co1/3Mn1/3O2 with graphene nanosheets and multiwall carbon nanotubes (MWCNTs) is assembled by using a hydrothermal method. In the composite, LiNi1/3Co1/3Mn1/3O2 and MWCNTs are wrapped into graphene nanosheets. It exhibits better rate capability in comparison with plain LiNi1/3Co1/3Mn1/3O2 as a positive electrode for an aqueous rechargeable battery, using zinc as the negative electrode. The average charge and discharge voltages of this aqueous rechargeable battery are 1.80 and 1.65 V, respectively. Based on the total weight of the electrode materials of the composite and Zn, its energy density can reach 154 Wh kg−1, which is comparable with that of Ni-MH batteries. Its cycling behavior is satisfactory.
Co-reporter:Y.Q. Yang, Z. Chang, M.X. Li, X.W. Wang, Y.P. Wu
Solid State Ionics 2015 Volume 269() pp:1-7
Publication Date(Web):January 2015
DOI:10.1016/j.ssi.2014.11.015
•A sodium ion conducting gel polymer electrolyte is prepared through a simple phase separation process.•It is a porous membrane based on poly(vinylidene difluoride-co-hexafluoropropylene).•The gel polymer electrolyte provides the sodium ionic conductivity of 0.60 mS cm− 1 at ambient temperature.•Its ionic transference number of sodium ion (tNa +) is 0.30, higher than that (0.17) in the commercial separator.A sodium ion conducting gel polymer electrolyte based on poly(vinylidene difluoride-co-hexafluoropropylene) porous membrane is reported, which is prepared through a simple phase separation process. It exhibits high safety, good mechanical properties and good electrochemical stability. The gel polymer electrolyte provides the sodium ionic conductivity of 0.60 mS cm− 1 at ambient temperature, while the commercial separator (Celgard 2730) offers only 0.16 mS cm− 1. The temperature dependence of the ionic conductivity from 25 to 75 °C is consistent with an Arrhenius-behavior. The ionic transference number of sodium ion (tNa+) in the gel polymer electrolyte is 0.30, higher than that (0.17) in the commercial separator. This provides a new direction to improve the safety of sodium ion batteries.
Co-reporter:Yusong Zhu;Shiying Xiao;Yi Shi;Yaqiong Yang;Yuyang Hou
Advanced Energy Materials 2014 Volume 4( Issue 1) pp:
Publication Date(Web):
DOI:10.1002/aenm.201300647
A composite membrane based on electrospun poly(vinylidene fluoride) (PVDF) and lithium polyvinyl alcohol oxalate borate (LiPVAOB) exhibiting high safety (self-extinguishing) and good mechanical property is prepared. The ionic conductivity of the as-prepared gel polymer electrolyte from this composite membrane saturated with 1 mol L−1 LiPF6 electrolyte at ambient temperature can be up to 0.26 mS cm−1, higher than that of the corresponding well-used commercial separator (Celgard 2730), 0.21 mS cm−1. Moreover, the lithium ion transference in the gel polymer electrolyte at room temperature is 0.58, twice as that in the commercial separator (0.27). Furthermore, the absorbed electrolyte solvent is difficult to evaporate at elevated temperature. Its electrochemical performance is evaluated by using LiFePO4 cathode. The obtained results suggest that this gel-type composite membrane shows great possibilities for use in large-capacity lithium ion batteries that require high safety.
Co-reporter:Zheng Chang, Xujiong Wang, Yaqiong Yang, Jie Gao, Minxia Li, Lili Liu and Yuping Wu
Journal of Materials Chemistry A 2014 vol. 2(Issue 45) pp:19444-19450
Publication Date(Web):01 Oct 2014
DOI:10.1039/C4TA04419C
A rechargeable lithium battery, Li//Br, is reported using an aqueous bromide/tribromide redox pair and a coated lithium metal as the positive and negative electrodes, respectively. The positive Br2 electrode shows fast redox kinetics and good stability. This battery presents excellent electrochemical performance with an average discharge voltage up to 3.96 V at 1.7 mA cm−2, an energy density of 1220 Wh kg−1, a power density of 29.7 mW cm−2 at a current density of 12.8 mA cm−2, and a long cycling life. There is no evidence of voltage decrease after 100 cycles at 35% DOD. It would become a good platform between lithium ion batteries and Li//air batteries since the former shows lower energy density and the latter has some challenging problems that need to be solved prior to practical application. This finding presents another promising choice for electrochemical energy storage systems.
Co-reporter:Zheng Chang, Yaqiong Yang, Minxia Li, Xiaowei Wang and Yuping Wu
Journal of Materials Chemistry A 2014 vol. 2(Issue 28) pp:10739-10755
Publication Date(Web):28 Feb 2014
DOI:10.1039/C4TA00565A
Widespread use of fossil fuels has resulted in many environmental problems. There is an urgent need to search for reliable green energy storage technologies. The electrical energy storage systems based on neutral aqueous solutions are attractive candidates compared to the present energy storage systems utilizing flammable and expensive organic electrolytes because of their improved safety, low cost and environmental friendliness. What is more, high-rate performance can be achieved due to the high ionic conductivity of the aqueous electrolytes. However, the lower electrochemical window of water limits the possible high output voltage and high energy density. Recently, many new concepts based on neutral aqueous energy storage chemistries including aqueous rechargeable batteries and supercapacitors have exhibited high power and energy densities, excellent cycling life and high Coulombic efficiency. The present paper reviews the latest advances in these new chemistries based on neutral aqueous electrolytes, and the challenges and outlooks in this field are briefly commented on and discussed.
Co-reporter:Yu Liu, Zubiao Wen, Xiongwei Wu, Xiaowei Wang, Yuping Wu and Rudolf Holze
Chemical Communications 2014 vol. 50(Issue 89) pp:13714-13717
Publication Date(Web):05 Sep 2014
DOI:10.1039/C4CC06622G
An acid-free lead rechargeable battery system comprising PbSO4 as the negative electrode, LiMn2O4 as the positive electrode and a neutral Li2SO4 aqueous solution as electrolyte is reported and its electrochemical performance is very good. It shows great promise to reduce the global use of lead by 50% since it is also low cost.
Co-reporter:Baihe Zhang, Yu Liu, Xiongwei Wu, Yaqiong Yang, Zheng Chang, Zubiao Wen and Yuping Wu
Chemical Communications 2014 vol. 50(Issue 10) pp:1209-1211
Publication Date(Web):25 Nov 2013
DOI:10.1039/C3CC48382G
An aqueous rechargeable battery system is assembled by using metallic zinc and Na0.95MnO2 as the negative and positive electrodes, respectively. It is cheap and environmentally friendly, and its energy density is 78 Wh kg−1. Its cycling performance is very good with only 8% capacity loss after 1000 cycles at 4 C between 1 and 2 V.
Co-reporter:C.L. Hu, H.H. Yi, F.X. Wang, S.Y. Xiao, Y.P. Wu, D. Wang, D.L. He
Journal of Power Sources 2014 Volume 255() pp:355-359
Publication Date(Web):1 June 2014
DOI:10.1016/j.jpowsour.2013.12.040
•A boron doped LiMnPO4 on P-site, LiMn(P0.9B0.1O4−δ), was synthesized using a simple solid state method.•Diffusion of lithium ions is improved and charge transfer resistance is decreased.•LiMn(P0.9B0.1O4−δ) shows better electrochemical performance compared to the virginal LiMnPO4.•The discharge capacity of LiMn(P0.9B0.1O4−δ) is 43% higher than that of the virginal LiMnPO4.•There is no capacity fading after 50 cycles.To improve the electrochemical performance of LiMnPO4 cathode for lithium ion battery, many efforts focus on cation doping/substitution on Mn-site. Here we synthesize a boron doped LiMnPO4 on P-site, LiMn(P0.9B0.1O4−δ), by a simple solid-state method. It is characterized by X-ray diffraction, scan electron microscopy, cyclic voltammograph, electrochemical impedance spectroscopy and capacity testing. Results show that its electrochemical performance is improved compared with the virginal LiMnPO4. It delivers a capacity of about 130 mAh g−1 at 0.1 C and remains 71% of the capacity at high discharge rate of 2 C. After 50 cycles at 0.2 C, there is no evident capacity fading.
Co-reporter:F.X. Wang, S.Y. Xiao, Y.S. Zhu, Z. Chang, C.L. Hu, Y.P. Wu, R. Holze
Journal of Power Sources 2014 Volume 246() pp:19-23
Publication Date(Web):15 January 2014
DOI:10.1016/j.jpowsour.2013.07.046
•LiMn2O4 nanohybrid has been prepared using α-MnO2 nanotubes and LiOH at 700 °C.•It consists of nanotubes, nanorods and nanoparticles.•Its formation mechanism is explained.•It exhibits a high specific capacitance of 415 F g−1 at 0.5 A g−1 in 0.5 mol l−1 Li2SO4 aqueous solution.•A supercapacitor using LiMn2O4 nanohybrid as the positive electrode in aqueous solution presents good cycling.A LiMn2O4 nanohybrid consisting of nanotubes, nanorods and nanoparticles has been synthesized using α-MnO2 nanotubes from hydrothermal reaction as a precursor. It is characterized with X-ray diffraction, field emission scanning electron and transmission electron microscopy. A formation mechanism is proposed. As a positive electrode material for supercapacitors, it exhibits a high specific discharge capacitance of 415 F g−1 at 0.5 A g−1 in 0.5 mol l−1 Li2SO4 aqueous solution. Even at 10 A g−1, it still has a specific discharge capacitance of 208 F g−1. The energy density of the asymmetric supercapacitor using activated carbon as the negative electrode and LiMn2O4-nanohybrid as the positive electrode in the aqueous solution in the voltage range of 0–1.8 V presents 29.8 Wh kg−1 at power density of 90 W kg−1. In addition, the cycling behavior of the asymmetric supercapacitor is good.
Co-reporter:B.H. Zhang, Y. Liu, Z. Chang, Y.Q. Yang, Z.B. Wen, Y.P. Wu, R. Holze
Journal of Power Sources 2014 Volume 253() pp:98-103
Publication Date(Web):1 May 2014
DOI:10.1016/j.jpowsour.2013.12.011
Co-reporter:Y. Liu, B.H. Zhang, S.Y. Xiao, L.L. Liu, Z.B. Wen, Y.P. Wu
Electrochimica Acta 2014 Volume 116() pp:512-517
Publication Date(Web):10 January 2014
DOI:10.1016/j.electacta.2013.11.077
A nanocomposite of molybdenum trioxide (MoO3) nanobelts coated with polypyrrole was prepared as an anode material for aqueous rechargeable sodium batteries (ARSBs). When nanowire Na0.35MnO2 is used as the cathode, the ARSB can deliver an energy density of 20 Wh kg−1 at 80 W kg−1 and even maintain 18 Wh kg−1 at 2.6 kW kg−1 in 0.5 mol L−1 Na2SO4 aqueous electrolyte, suggesting a good rate capability that can be comparable with supercapacitors. In addition, its cycling behavior is greatly improved compared with the virginal MoO3. This will provide a new direction to explore non-carbon anode materials for ARSBs with excellent electrochemical performance. This good performance exhibits that this battery will be a promising candidate for the storage of solar and wind energies.
Co-reporter:R. Holze, Y.P. Wu
Electrochimica Acta 2014 Volume 122() pp:93-107
Publication Date(Web):10 March 2014
DOI:10.1016/j.electacta.2013.08.100
The use of intrinsically conducting polymers (ICPs) like polythiophene (PTh), polypyrrole (PPy) and polyaniline (PANI) in devices and systems for electrochemical energy storage and conversion is briefly reviewed with a focus on an overview distinguishing between already established uses and potential applications. Basic principles in these three major fields are highlighted:•ICPs as active masses.•ICPs as conductance-enhancing additives.•ICPs as auxiliary materials beyond conductance.
Co-reporter:Lei Zhu, Wenyi Wu, Xiaowei Wang, Xiongwei Wu, Weiping Tang and Yuping Wu
RSC Advances 2014 vol. 4(Issue 103) pp:59088-59093
Publication Date(Web):23 Oct 2014
DOI:10.1039/C4RA09209K
A hybrid of CoOOH nanorods with conductive MWCNTs is successfully prepared. Due to the introduction of MWCNTs, the diameter of the CoOOH nanorods is smaller than that of pristine CoOOH nanorods. Because of the conductive nanostructure network and smaller diameter of the CoOOH nanorods, it exhibits high capacitance, good high-rate capability and excellent cycling performance as a positive electrode for supercapacitors in a 0.5 mol L−1 KOH aqueous electrolyte. Its specific capacity is 312 F g−1 at the current density of 1 A g−1, and 182 F g−1 even at the current density of 10 A g−1. After 10000 full cycles, the capacitance retention is 97%. The hybrid is of great promise for practical application.
Co-reporter:Lili Liu, Yuyang Hou, Yaqiong Yang, Minxia Li, Xiaowei Wang and Yuping Wu
RSC Advances 2014 vol. 4(Issue 18) pp:9086-9091
Publication Date(Web):22 Jan 2014
DOI:10.1039/C3RA48034H
A Se/C composite was prepared by a simple combination method of ball milling and low temperature treatment as a cathode material for Li–Se rechargeable batteries. It was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Its electrochemical performance as a cathode material for lithium rechargeable batteries was tested by cyclic voltammetry (CV) and capacity measurements. Rate capacity and cycling performance of the as-prepared product are very satisfactory. Even at a current density of 500 mA g−1, the composite can deliver a capacity of 187 mA h g−1. The main reason is that the high conductivity of carbon decreases its charge transfer resistance and effectively suppresses the dissolution of oxidation products from the composite cathode.
Co-reporter:Shiying Xiao, Faxing Wang, Yaqiong Yang, Zheng Chang and Yuping Wu
RSC Advances 2014 vol. 4(Issue 1) pp:76-81
Publication Date(Web):07 Nov 2013
DOI:10.1039/C3RA46115G
A green and environmentally friendly polymer, methyl cellulose (MC), is used as a host matrix of a gel polymer electrolyte for lithium ion batteries. It shows good mechanical performance and thermal stability. The ionic conductivity of the gel polymer electrolyte is 0.20 mS cm−1 and it has a higher lithium ion transference number (t+ = 0.29) than the commercial separator (0.27). When evaluated using LiFePO4 as cathode and Li metal as the counter and reference electrode, the LiFePO4 cathode exhibits relatively higher reversible capacity for the gel polymer electrolyte than that for the commercial separator. In addition, the rate capability and cycling performance are also comparable with those for the commercial separator. This provides another direction for gel polymer electrolytes and environmental protection.
Co-reporter:Dr. Yi Shi;Dr. Jie Gao; Héctor D. Abruña; Hui-Jun Li; Hua-Kun Liu;Dr. David Wexler; Jia-Zhao Wang; Yuping Wu
Chemistry - A European Journal 2014 Volume 20( Issue 19) pp:5608-5612
Publication Date(Web):
DOI:10.1002/chem.201400118
Abstract
In recent years, the controlled synthesis of inorganic micro- and nanostructures with hollow interiors has attracted considerable attention because of their widespread potential applications. A feasible method for synthesizing Li3VO4 by a template-free, solution synthesis of single-crystalline microboxes with well-defined non-spherical morphologies has been reported. This study provides the useful information to produce other hollow structure materials to the broad audience of readers. The formation of hollow structure and the influence of raw materials have been presented. The thus-synthesized Li3VO4 exhibited significantly improved conductivity, rate capability, and cycling life compared to commercial graphite, synthesized Li4Ti5O12, and previously reported Li3VO4.
Co-reporter:Yi Shi, Jie Gao, Héctor D. Abruña, Huakun Liu, Huijun Li, Jiazhao Wang, Yuping Wu
Nano Energy 2014 Volume 8() pp:297-304
Publication Date(Web):September 2014
DOI:10.1016/j.nanoen.2014.06.009
•Li4Ti5O12/graphene has been synthesized by an advanced MW-HT method.•Li4Ti5O12 microspheres composed of nanoflakes/particles wrapped in graphene sheets.•A superior rate capacity, stable cycling and conductivity than Li4Ti5O12.Li4Ti5O12 microspheres composed of nanoflakes wrapped in graphene nanosheets have been synthesized by an advanced microwave-hydrothermal (MW-HT) method for the preparation following by an annealing step. Microwave-assisted synthesis processes are appealing, as they can rapidly synthesize materials with a high degree of control of particle size and morphology at low cost. The resultant composite reveals a unique loose structure which could avoid the restacking of graphene sheets and offer rapid lithium ion diffusion paths. Therefore the Li4Ti5O12/graphene electrode has highly desirable properties: a specific capacity approaching the theoretical value, stable cycling, and exceptional rate capability. The composite also can be a good indicator of the remained charge and discharge capacity since it presents a curved charge and discharge line instead of a stable plateau.
Co-reporter:Yusong Zhu, Faxing Wang, Lili Liu, Shiying Xiao, Zheng Chang and Yuping Wu
Energy & Environmental Science 2013 vol. 6(Issue 2) pp:618-624
Publication Date(Web):26 Nov 2012
DOI:10.1039/C2EE23564A
A composite membrane of a nonwoven fabric with poly(vinylidene fluoride) exhibiting high safety (self-extinguishing), good mechanical property and low cost is reported. The ionic conductivity of the as-prepared gel membrane saturated with 1 mol l−1 LiPF6 electrolyte at ambient temperature can be up to 0.30 mS cm−1, higher than that of the corresponding well-used commercial separator (Celgard 2730), 0.21 mS cm−1. Moreover, the lithium ion transference in the gel membrane at room temperature is almost twice that in the commercial separator. Furthermore, the absorbed solvent is difficult to evaporate at elevated temperature. Its electrochemical performance is evaluated by using a LiFePO4 cathode. The obtained results suggest that this gel-type composite membrane is very attractive for large-capacity battery systems requiring high safety and low cost.
Co-reporter:Wei Tang, Yusong Zhu, Yuyang Hou, Lili Liu, Yuping Wu, Kian Ping Loh, Hanping Zhang and Kai Zhu
Energy & Environmental Science 2013 vol. 6(Issue 7) pp:2093-2104
Publication Date(Web):10 May 2013
DOI:10.1039/C3EE24249H
Due to the energy crisis within recent decades, renewable energies such as solar, wind and tide energies have received a lot of attention. However, these renewable energies are dependent on the time and season. Consequently, energy storage systems are needed to fully utilize these energies including their connection with smart grids. Aqueous rechargeable lithium batteries (ARLBs) may be an ideal energy storage system due to its excellent safety and reliability. However, since the introduction of ARLBs in 1994, the progress on improving their performance has been very limited. Recently, their rate performance, especially superfast charging performance, reversible capacity and cycling life of their electrode materials were markedly improved. The present work reviews the latest advances in the exploration of the electrode materials and the development of battery systems. Also the main challenges in this field are briefly commented on and discussed.
Co-reporter:Wei Tang, Yuyang Hou, Faxing Wang, Lili Liu, Yuping Wu, and Kai Zhu
Nano Letters 2013 Volume 13(Issue 5) pp:2036-2040
Publication Date(Web):March 28, 2013
DOI:10.1021/nl400199r
LiMn2O4 nanotube with a preferred orientation of (400) planes is prepared by using multiwall carbon nanotubes as a sacrificial template. Because of the nanostructure and preferred orientation, it shows a superfast second-level charge capability as a cathode for aqueous rechargeable lithium battery. At the charging rate of 600C (6 s), 53.9% capacity could be obtained. Its reversible capacity can be 110 mAh/g, and it also presents excellent cycling behavior due to the porous tube structure to buffer the strain and stress from Jahn–Teller effects.
Co-reporter:Yi Shi, Jia-Zhao Wang, Shu-Lei Chou, David Wexler, Hui-Jun Li, Kiyoshi Ozawa, Hua-Kun Liu, and Yu-Ping Wu
Nano Letters 2013 Volume 13(Issue 10) pp:4715-4720
Publication Date(Web):September 11, 2013
DOI:10.1021/nl402237u
To explore good anode materials of high safety, high reversible capacity, good cycling, and excellent rate capability, a Li3VO4 microbox with wall thickness of 40 nm was prepared by a one-pot and template-free in situ hydrothermal method. In addition, its composite with graphene nanosheets of about six layers of graphene was achieved. Both of them, especially the Li3VO4/graphene nanosheets composite, show superior electrochemical performance to the formerly reported vanadium-based anode materials. The composite shows a reversible capacity of 223 mAh g–1 even at 20C (1C = 400 mAh g–1). After 500 cycles at 10C there is no evident capacity fading.
Co-reporter:Neeraj Sharma, Dehong Yu, Yusong Zhu, Yuping Wu, and Vanessa K. Peterson
Chemistry of Materials 2013 Volume 25(Issue 5) pp:754
Publication Date(Web):February 19, 2013
DOI:10.1021/cm303851w
Lithium-ion batteries are undergoing rapid development to meet the energy demands of the transportation and renewable energy-generation sectors. The capacity of a lithium-ion battery is dependent on the amount of lithium that can be reversibly incorporated into the cathode. This work directly quantifies the time- and current-dependent lithium transfer within a cathode functioning under conventional charge–discharge cycling. We examine Li1+yMn2O4 under real working conditions using in situ neutron powder diffraction and link the atomic-scale structure to the battery performance. The lithium location and content, oxygen positional parameter, and lattice parameter of the cathode are measured and linked to the battery’s charge/discharge characteristics. Lithium insertion (discharge) differs from extraction (charge), a feature that may explain the relative ease of discharge (compared with charge) of this material. An atomic-scale understanding of cathode functionality, such as revealed here, will direct improvements in battery performance at both the practical and the fundamental level.Keywords: battery; cathode; in situ neutron diffraction; lithium manganate; lithium occupancy; neutron scattering; structure−property relationships;
Co-reporter:Bin Wang, Jianli Cheng, Yuping Wu, Dan Wang and Dannong He
Journal of Materials Chemistry A 2013 vol. 1(Issue 4) pp:1368-1373
Publication Date(Web):08 Nov 2012
DOI:10.1039/C2TA00487A
Carbon fibers with in situ incorporation of nickel were prepared by electrospinning a solution of a polyacrylonitrile dissolved in a dimethylformamide solution with nickel nitrate, followed by thermal treatment. The prepared one-dimensional composite fibers are uniformly dispersed with an electronic conducting Ni network. As an anode material for lithium-ion batteries, their electrochemical behaviors were measured by cyclic voltammetry, constant current density testing and electrochemical impedance spectroscopy. The carbon/Ni fiber electrode maintains a high reversible capacity of about 457 mA h g−1 after 50 cycles. When tested at different current densities, it shows excellent rate capability with high reversible capacity.
Co-reporter:Yuyang Hou, Xujiong Wang, Yusong Zhu, Chenglin Hu, Zheng Chang, Yuping Wu and Rudolf Holze
Journal of Materials Chemistry A 2013 vol. 1(Issue 46) pp:14713-14718
Publication Date(Web):27 Sep 2013
DOI:10.1039/C3TA13472E
Our former research found that lithium metal coated with a gel polymer electrolyte and LISICON film can be stable in aqueous electrolytes to carry out lithium plating and dissolution, and is a good anode for high energy density aqueous rechargeable lithium batteries (ARLBs). Here we prepared three-dimensionally macroporous LiFePO4 and used it as the cathode to build another ARLB in 0.5 mol l−1 Li2SO4 aqueous solution. Its stable output voltage is 3.32 V with excellent cycling performance and good rate capability. Its energy density is much higher than that of previously reported traditional ARLBs, and is also higher than those for traditional lithium ion batteries based on graphitic carbon/organic electrolyte/LiFePO4. Its safety and reliability are also very good. The results suggests that the chemistry of post lithium ion batteries is of great promise for practical applications in electric vehicles.
Co-reporter:Yu Liu, Baihe Zhang, Yaqiong Yang, Zheng Chang, Zubiao Wen and Yuping Wu
Journal of Materials Chemistry A 2013 vol. 1(Issue 43) pp:13582-13587
Publication Date(Web):09 Sep 2013
DOI:10.1039/C3TA12902K
A nanocomposite of molybdenum trioxide (α-MoO3) nanobelts coated with polypyrrole has been fabricated by a simple in situ polymerization route. The structure, morphology and electrochemical performance of the nanocomposite were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and electrochemical measurements. It was found that the polypyrrole acted as a conducting matrix and a coating agent, which effectively improves the conductivity of the MoO3 nanobelts and inhibits the dissolution of molybdenum ions during cycling. The supercapacitor based on the PPy@MoO3 nanocomposite as the anode, activated carbon as the cathode and 0.5 M K2SO4 aqueous solution as the electrolyte exhibits better rate capability as well as excellent cycling performance compared to the virginal MoO3.
Co-reporter:Yusong Zhu, Shiying Xiao, Yi Shi, Yaqiong Yang and Yuping Wu
Journal of Materials Chemistry A 2013 vol. 1(Issue 26) pp:7790-7797
Publication Date(Web):26 Apr 2013
DOI:10.1039/C3TA00167A
A composite membrane based on poly(vinylidene fluoride) (PVDF) and lithium polyacrylic acid oxalate borate (LiPAAOB) exhibiting high safety (self-extinguishing) and good mechanical property was prepared. The ionic conductivity of the gel polymer electrolyte (GPE) by saturating with 1 mol L−1 LiPF6 electrolyte at ambient temperature can be up to 0.35 mS cm−1, higher than that of the well-used commercial separator (Celgard 2730), 0.21 mS cm−1. The lithium ion transference in the GPE at room temperature is 0.58, twice that in the commercial separator (0.27). Moreover, the GPE presents a true shut-down behavior, which is quite different from the not-real shut-down behaviour of the commercial separators. Furthermore, the absorbed electrolyte solvent is difficult to evaporate at elevated temperature. Its electrochemical performance is evaluated by using LiFePO4 cathode. The obtained results suggest that this composite GPE is very attractive to large-capacity battery systems requiring high safety and low cost.
Co-reporter:Lili Liu, Yuyang Hou, Xiongwei Wu, Shiying Xiao, Zheng Chang, Yaqiong Yang and Yuping Wu
Chemical Communications 2013 vol. 49(Issue 98) pp:11515-11517
Publication Date(Web):09 Oct 2013
DOI:10.1039/C3CC46943C
Nanoporous selenium was prepared by a simple mechanical method adopting nano-CaCO3 as a template. When used as a cathode, it can exhibit relatively high capacity and good cycling behaviour. These results present great promise for this new cathode material for rechargeable lithium batteries of high energy density.
Co-reporter:Faxing Wang, Shiying Xiao, Zheng Chang, Yaqiong Yang and Yuping Wu
Chemical Communications 2013 vol. 49(Issue 80) pp:9209-9211
Publication Date(Web):10 Jul 2013
DOI:10.1039/C3CC44360D
Nanoporous LiNi1/3Co1/3Mn1/3O2 (NP-NCM) was synthesized by using vapour grown carbon fibers (VGCFs) as templates. It exhibits excellent electrochemical performance as a cathode material for aqueous rechargeable lithium batteries, especially with ultra-fast charge capability, and 72 mA h g−1 can be achieved at a charge time of 20 s.
Co-reporter:Xujiong Wang, Qunting Qu, Yuyang Hou, Faxing Wang and Yuping Wu
Chemical Communications 2013 vol. 49(Issue 55) pp:6179-6181
Publication Date(Web):17 May 2013
DOI:10.1039/C3CC42676A
Using a coated Li metal as an anode and LiCoO2 as a cathode, an aqueous rechargeable battery is built up, whose average discharge voltage is 3.70 V. This high voltage stability is due to the “cross-over” effect of Li+ ions, which is different from the traditional ways of increasing overpotentials. The total energy density can be 465 W h kg−1.
Co-reporter:L.L. Liu, X.J. Wang, Y.S. Zhu, C.L. Hu, Y.P. Wu, R. Holze
Journal of Power Sources 2013 Volume 224() pp:290-294
Publication Date(Web):15 February 2013
DOI:10.1016/j.jpowsour.2012.09.100
A polypyrrole-coated LiV3O8 nanocomposite was prepared as anode material (negative mass) for aqueous rechargeable lithium batteries and characterized by X-ray diffraction, scanning electron microscopy, and electrochemical measurements. Polypyrrole acts as a conducting matrix as well as a coating agent, which held LiV3O8 nanorods inside the particles during the charge/discharge cycles. Results show that the electrochemical performance of the PPy@LiV3O8 nanocomposite is significantly enhanced showing higher capacity and better rate capability as well as better cycling performance compared to pristine LiV3O8.Highlights► A polypyrrole-coated LiV3O8-nanocomposite was prepared. ► It is suggested as anode material for aqueous rechargeable lithium batteries. ► Polypyrrole acts as a conducting matrix as well as a volume change buffer agent. ► It holds LiV3O8 nanorods inside the particles during the charge/discharge cycles. ► Electrochemical performance of PPy@LiV3O8 is significantly enhanced.
Co-reporter:Jie Shao, Xinyong Li, Qunting Qu, Yuping Wu
Journal of Power Sources 2013 Volume 223() pp:56-61
Publication Date(Web):1 February 2013
DOI:10.1016/j.jpowsour.2012.09.046
The charge/discharge, electrochemical impedance, cyclic voltammogram, and cycling behaviors of crystalline KxMnO2·nH2O as cathode material for supercapacitors in Li2SO4, Na2SO4, and K2SO4 electrolytes were compared. The different power and cycling performance of KxMnO2·nH2O during charge/discharge in the three electrolytes were elucidated by analyzing its composition and structure evolution. Compared with the Li2SO4 and Na2SO4 electrolytes, the highest ionic conductivity of K2SO4 electrolyte, the fastest charge-transfer process and slightest structural evolution of KxMnO2·nH2O during charge/discharge in the K2SO4 electrolyte lead to a superior power and cycling behavior for supercapacitor application.Highlights► KxMnO2·nH2O presents different electrochemical behaviors in three aqueous electrolytes. ► The reasons for the different electrochemical behaviors were elucidated. ► KxMnO2·nH2O displays a superior power and cycling performance in K2SO4 electrolyte.
Co-reporter:F.X. Wang, S.Y. Xiao, Y. Shi, L.L. Liu, Y.S. Zhu, Y.P. Wu, J.Z. Wang, R. Holze
Electrochimica Acta 2013 Volume 93() pp:301-306
Publication Date(Web):30 March 2013
DOI:10.1016/j.electacta.2013.01.106
Ni-doped spinel LiNixMn2−xO4 (x = 0, 0.05, 0.10) samples were prepared by a sol–gel method. Structure and morphology of the samples were characterized by X-ray diffraction, scanning electron microscopy, Brunnauer–Emmet–Teller method and inductively coupled plasma atomic absorption spectrometry. The electrochemical behavior as a cathode material (positive mass) for aqueous rechargeable lithium batteries (ARLBs) was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, capacity measurements and cycling tests. The results show that the LiNi0.1Mn1.9O4 electrode presents the best rate and cycling performance but low reversible capacity. In contrast, the LiNi0.05Mn1.95O4 electrode shows a higher reversible capacity and relatively good cycling behavior. At a current density of 150 mA g−1, LiNi0.05Mn1.95O4 delivers a reversible capacity of 102 mA h g−1. At the relative high current densities of 1500 and 3000 mA g−1, the LiNi0.05Mn1.95O4 electrode still delivers reversible capacities of 95.0 and 88.7 mA h g−1, respectively. The Ni-doped samples show excellent cycling life in 0.5 mol L−1 Li2SO4 aqueous solution. The capacity retention ratios for LiNi0.05Mn1.95O4 and LiNi0.10Mn1.90O4 after 800 cycles at a current density of 1500 mA g−1 are 79.4% and 91.1%, respectively, much higher than that for the undoped LiMn2O4 at only 37.8%.
Co-reporter:Q.T. Qu, L.L. Liu, Y.P. Wu, R. Holze
Electrochimica Acta 2013 Volume 96() pp:8-12
Publication Date(Web):30 April 2013
DOI:10.1016/j.electacta.2013.02.078
The electrochemical behavior of V2O5·0.6H2O nanoribbons in 0.5 mol/L Li2SO4, Na2SO4, and K2SO4 aqueous solutions is compared. The electrochemical reaction of V2O5·0.6H2O in these neutral aqueous electrolyte solutions was elucidated by analyzing the different electrochemical behavior, structural and composition changes of V2O5·0.6H2O electrodes during charge/discharge. Results show, that V2O5·0.6H2O exhibits the largest specific capacity in K2SO4 electrolyte attributed to the most facile intercalation/deintercalation of K+-ions into/from the interlayer space of V2O5·0.6H2O.
Co-reporter:Y.S. Zhu, X.J. Wang, Y.Y. Hou, X.W. Gao, L.L. Liu, Y.P. Wu, M. Shimizu
Electrochimica Acta 2013 Volume 87() pp:113-118
Publication Date(Web):1 January 2013
DOI:10.1016/j.electacta.2012.08.114
In this study, a novel single-ion conducting polymer electrolyte, lithium polyvinyl alcohol oxalate borate (LiPVAOB), from the reaction of poly(vinyl alcohol) (PVA) with different molar ratio of boric acid, oxalic acid and lithium carbonate was prepared. The prepared materials were characterized by Fourier transformation infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry (TG), differential thermal analysis (DTA), electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry. Ionic conductivity of these polymer electrolytes from adding an assistant (about 20 wt.% propylene carbonate) is dependent on molar ratio of the reactants and can up to 6.11 × 10−6 S cm−1 at ambient temperature. Their electrochemical window can be stable up to 7 V (vs. Li+/Li), which is of great attraction for high voltage lithium ion batteries with high energy density.Highlights► A novel single-ion conducting polymer electrolyte, lithium polyvinyl alcohol oxalate borate (LiPVAOB), was prepared. ► It is from the reaction of poly(vinyl alcohol) with boric acid, lithium hydroxide and oxalic acid. ► The prepared materials act as single-ion polymer electrolytes. ► Their electrochemical window can be stable up to 7 V (vs. Li+/Li). ► They are of great attraction for high voltage lithium ion batteries with high energy density.
Co-reporter:Faxing Wang, Shiying Xiao, Yuyang Hou, Chenglin Hu, Lili Liu and Yuping Wu
RSC Advances 2013 vol. 3(Issue 32) pp:13059-13084
Publication Date(Web):16 Apr 2013
DOI:10.1039/C3RA23466E
An asymmetric supercapacitor (ASC) is a supercapacitor based on two different electrode materials. One electrode is based on redox (Faradic) reactions with or without non-faradic reactions, and the other one is mostly based on electric double-layer (non-Faradic or electrostatic) absorption/desportion. Aqueous electrolytes have higher ionic conductivity, larger capacitance and better safety than the organic electrolytes. Herein, some key electrode materials for aqueous ASCs are primarily reviewed, which provide a new direction for power sources to have higher energy density at high power densities, compared with traditional capacitors. Their negative electrode materials include carbonaceous materials (porous carbons, carbon nanotubes and graphene), oxides (V2O5 and MoO3) and their composites, and their positive electrode materials include carbonaceous materials, oxides (RuO2, MnO2, MoO3, V2O5, PbO2, Co3O4), Ni(OH)2, intercalation compounds (LiCoO2, LiMn2O4, Li[NiCoMn]1/3O2, NaMnO2 and KMnO2). We describe the latest work on these electrode materials, and a particular focus is directed to the fabrication and electrochemical performance of various nanostructured electrode materials and some assembled ASCs. Finally, the future trends and prospects on advanced energy storage materials are suggested.
Co-reporter:Dr. Jianli Cheng;Dr. Bin Wang;Dr. Cheol-Min Park;Dr. Yuping Wu;Dr. Hui Huang;Dr. Fude Nie
Chemistry - A European Journal 2013 Volume 19( Issue 30) pp:9866-9874
Publication Date(Web):
DOI:10.1002/chem.201300037
Abstract
By using carbon nanotubes (CNTs) as a shape template and glucose as a carbon precursor and structure-directing agent, CNT@Fe3O4@C porous core/sheath coaxial nanocables have been synthesized by a simple one-pot hydrothermal process. Neither a surfactant/ligand nor a CNT pretreatment is needed in the synthetic process. A possible growth mechanism governing the formation of this nanostructure is discussed. When used as an anode material of lithium-ion batteries, the CNT@Fe3O4@C nanocables show significantly enhanced cycling performance, high rate capability, and high Coulombic efficiency compared with pure Fe2O3 particles and Fe3O4/CNT composites. The CNT@Fe3O4@C nanocables deliver a reversible capacity of 1290 mA h g−1 after 80 cycles at a current density of 200 mA g−1, and maintain a reversible capacity of 690 mA h g−1 after 200 cycles at a current density of 2000 mA g−1. The improved lithium storage behavior can be attributed to the synergistic effect of the high electronic conductivity support and the inner CNT/outer carbon buffering matrix.
Co-reporter:Qunting Qu;Yusong Zhu;Xiangwen Gao
Advanced Energy Materials 2012 Volume 2( Issue 8) pp:950-955
Publication Date(Web):
DOI:10.1002/aenm.201200088
Co-reporter:Wei Tang, Xiangwen Gao, Yusong Zhu, Yunbo Yue, Yi Shi, Yuping Wu and Kai Zhu
Journal of Materials Chemistry A 2012 vol. 22(Issue 38) pp:20143-20145
Publication Date(Web):08 Aug 2012
DOI:10.1039/C2JM34563C
A hybrid of V2O5 nanowires and MWCNTs coated with polypyrrole (PPy) was prepared as an anode material for ARLBs. The hybrid shows a good electrochemical reversibility since the PPy coating can effectively prevent the dissolution of the reduced vanadium ions.
Co-reporter:Yi Shi, Shu-Lei Chou, Jia-Zhao Wang, David Wexler, Hui-Jun Li, Hua-Kun Liu and Yuping Wu
Journal of Materials Chemistry A 2012 vol. 22(Issue 32) pp:16465-16470
Publication Date(Web):20 Jun 2012
DOI:10.1039/C2JM32649C
To reduce the reaction time, electrical energy consumption, and cost, LiFePO4/C/graphene has been synthesized by a rapid, one-pot, microwave-assisted hydrothermal method within 15 min at a temperature of 200 °C, followed by sintering at 600 °C for 2 h under a H2/Ar (5:95, v/v) atmosphere. The microstructure and morphology of the LiFePO4/C/graphene products were characterized by means of X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. The carbon coated LiFePO4/C nanoparticles, around 200 nm in size, are thoroughly wrapped by crumpled micrometer-size graphene sheets. In this kind of structure, the bridging graphene nanosheets can form an effective conducting network and provide interconnected open pores that favor electrolyte absorption and reduce the diffusion path of the lithium ions. The cyclic voltammograms, charge/discharge profiles, and AC impedance measurements indicated that the kinetics of the LiFePO4/C/graphene was better than that of LiFePO4/C. The LiFePO4/C/graphene composite exhibited a discharge capacity of 165 mA h g−1 at 0.1 C and 88 mA h g−1 at 10 C, respectively. Therefore, the LiFePO4/C/graphene composite is a promising candidate for the development of high-performance, cost-effective lithium batteries for the hybrid vehicle and electric vehicle markets.
Co-reporter:Lichun Yang, Lili Liu, Yusong Zhu, Xujiong Wang and Yuping Wu
Journal of Materials Chemistry A 2012 vol. 22(Issue 26) pp:13148-13152
Publication Date(Web):30 Apr 2012
DOI:10.1039/C2JM31364B
Carbon coated MoO2 nanobelts were successfully synthesized via a hydrothermal method followed by calcination under inert atmosphere, using α-MoO3 nanobelts as the precursor and self-template, ethanol as the reducer and glucose as the carbon source. Under the protection of polysaccharide resulting from glucose polycondensation, the 1-D morphology can be well retained during the reduction and carbonization processes. Tested as anode materials for lithium ion batteries, the carbon coated MoO2 nanobelts exhibit a reversible capacity of 769.3 mA h g−1 at a current density of 100 mA g−1 in the first cycle, and retain 80.2% of the capacity after 30 cycles. When the current density increases, this material shows high rate capability and good cycling performance.
Co-reporter:W. Tang, Y.Y. Hou, X.J. Wang, Y. Bai, Y.S. Zhu, H. Sun, Y.B. Yue, Y.P. Wu, K. Zhu, R. Holze
Journal of Power Sources 2012 Volume 197() pp:330-333
Publication Date(Web):1 January 2012
DOI:10.1016/j.jpowsour.2011.09.050
A hybrid of MnO2-nanowires and MWCNTs to be used as cathode in a supercapacitor with good electrochemical performance was prepared by a facile hydrothermal method. In this hybrid the α-MnO2 nanowires are well entangled with MWCNTs. The MWCNTs provide a network for fast electron transport whereas MnO2 nanowires show a fast redox response. Since gain/loss of both electrons and ions can be realized very rapidly at the same time, the hybrid has an excellent rate capability and delivers an energy density of 17.8 Wh kg−1 at 400 W kg−1, which is maintained almost constant even at 3340 W kg−1 in 0.5 M Li2SO4 aqueous electrolyte. The cycling behavior is very good even in the presence of oxygen. The data present great promise for the hybrid as a practical cathode material for aqueous supercapacitor.Highlights► Well entangled hybrids of MnO2 nanowires and MWCNTs are obtained by a facile method. ► Their electrochemical performance as cathode for supercapacitors in 0.5 mol l−1 Li2SO4 aqueous electrolyte is reported. ► The energy density (17.8 Wh kg−1) of the supercapacitor stays almost unchanged with power density from 400 to 3340 W kg−1. ► The energy density of the supercapacitor does not fade much after 13,000 cycles.
Co-reporter:W. Tang, X.J. Wang, Y.Y. Hou, L.L. Li, H. Sun, Y.S. Zhu, Y. Bai, Y.P. Wu, K. Zhu, T. van Ree
Journal of Power Sources 2012 Volume 198() pp:308-311
Publication Date(Web):15 January 2012
DOI:10.1016/j.jpowsour.2011.09.106
A nanochain of LiMn2O4 was prepared by a sol–gel method using an aqueous solution of metal salts containing starch. Its electrochemical behavior was characterized by cyclic voltammography, capacity measurement and cycling performance. The results obtained show that the nanochain LiMn2O4 cathode has a very good rate capability. It shows a reversible capacity of 100 mAh g−1 at 100 mA g−1 (about 1 C) and 58 mAh g−1 even at a charge rate of 20 C. In addition, when the cathode is charged at 1 C, 70 mAh g−1 (70% capacity at 1 C) can be achieved even at a discharge rate of 50 C, with a cut-off voltage of 3.0 V in 1 M LiClO4 solution of EC/DEC/DMC (1:1:1, v/v/v). Furthermore, the cycling behavior of the cathode is also very satisfactory. This suggests that this nanochain LiMn2O4 has great promise for practical application as high rate cathode material for lithium ion batteries.Highlights► We prepared a nanochain LiMn2O4 by a starch-assisted sol–gel method. ► Its electrochemical performance as cathode for lithium ion batteries was tested. ► At the charge rate of 20 C, its reversible capacity is 58 mAh g−1. ► At the discharge rate of 50 C, 70 mAh g−1 can be achieved. ► Its cycling behavior is also very good. ► This nanochain LiMn2O4 has great promise for practical application as high rate cathode material.
Co-reporter:Y.S. Zhu, X.W. Gao, X.J. Wang, Y.Y. Hou, L.L. Liu, Y.P. Wu
Electrochemistry Communications 2012 Volume 22() pp:29-32
Publication Date(Web):August 2012
DOI:10.1016/j.elecom.2012.05.022
A novel single-ion polymer electrolyte, LiPAAOB (lithium oxalate polyacrylic acid borate), was prepared with different ratio of polyacrylic acid, boric acid, lithium hydroxide and oxalic acid. The obtained membranes were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetry and differential thermal analysis. After absorbing 3% solvent (propylene carbonate), the as-prepared LiOPAAB presents a single ion conductive behavior. Its ionic conductivity at ambient temperature can be up to 2.3 × 10− 6 S cm− 1 and electrochemical window can be stable up to 7.0 V (vs. Li+/Li), which is of great attraction for 5 V lithium ion batteries with high energy density.Highlights► A novel single-ion polymer electrolyte, LiOPAAB, was prepared. ► The structure of LiOPAAB is similar to that of LiBOB. ► Its ambient temperature ionic conductivity can be up to 2.3 × 10− 6 S cm− 1. ► Its electrochemical window can be stable up to 7.0 V (vs. Li+/Li). ► This single polymer electrolyte is of great attraction for 5 V lithium ion batteries with high energy density.
Co-reporter:B. Wang, J.L. Cheng, Y.P. Wu, D. Wang, D.N. He
Electrochemistry Communications 2012 Volume 23() pp:5-8
Publication Date(Web):September 2012
DOI:10.1016/j.elecom.2012.07.003
We report a facile and scalable electrospinning method for preparing porous NiO fiber material by using a carbonized carbon as the self-sacrificing template. The as-prepared NiO fibers demonstrated a good electrochemical performance as anode materials for Li-ion batteries, including high reversible capacity of approximately 638 mAh g− 1 over 50 cycles, high rate capability with a discharge capacity of 477 mAh g− 1 even at a current density of 1760 mA g− 1, and good cycling performance.Highlights► A novel porous NiO fiber material was prepared by a facile and scalable electrospinning method. ► This method uses a carbonized carbon as the self-sacrificing template. ► The electrochemical performance as anode materials for Li-ion batteries is excellent. ► Its reversible capacity is approximately 638 mAh g− 1 over 50 cycles. ► At the current density of 1760 mA g− 1 it still presents a discharge capacity of 477 mAh g− 1.
Co-reporter:Qunting Qu, Lijun Fu, Xiaoyun Zhan, Dominik Samuelis, Joachim Maier, Lei Li, Shu Tian, Zhaohui Li and Yuping Wu
Energy & Environmental Science 2011 vol. 4(Issue 10) pp:3985-3990
Publication Date(Web):14 Apr 2011
DOI:10.1039/C0EE00673D
A porous LiMn2O4 consisting of nano grains was prepared by using polystyrene as template. It was studied as a cathode material for aqueous rechargeable lithium batteries (ARLBs) using 0.5 mol l−1Li2SO4 aqueous solution as the electrolyte. Charge and discharge capacities at a current density of 10 A g−1 (about 90C) were 76% and 95% of the total capacity (118 mAh g−1), respectively. The power density can be up to 10000 W kg−1 and the cycling behavior is excellent. After 10000 cycles at 9C with 100% DOD (depth of discharge), the capacity retention of porous LiMn2O4 is 93%, which indicates that it can be used for a lifetime without maintenance. The main reasons for its excellent electrochemical performance are due to the nano grains, porous morphology and high crystalline structure. In addition, the acid-free aqueous electrolyte prevents Mn2+ from dissolution. These excellent results suggest a great promise for the development of aqueous rechargeable lithium batteries (ARLBs) in practical application.
Co-reporter:Wei Tang, Lili Liu, Shu Tian, Lei Li, Yunbo Yue, Yuping Wu and Kai Zhu
Chemical Communications 2011 vol. 47(Issue 36) pp:10058-10060
Publication Date(Web):09 Aug 2011
DOI:10.1039/C1CC13474D
MoO3 nanoplates were prepared as anode material for aqueous supercapacitors. They can deliver a high energy density of 45 W h kg−1 at 450 W kg−1 and even maintain 29 W h kg−1 at 2 kW kg−1 in 0.5 M Li2SO4 aqueous electrolyte. These results present a new direction to explore non-carbon anode materials.
Co-reporter:W. Tang, L.L. Liu, S. Tian, L. Li, L.L. Li, Y.B. Yue, Y. Bai, Y.P. Wu, K. Zhu, R. Holze
Electrochemistry Communications 2011 Volume 13(Issue 11) pp:1159-1162
Publication Date(Web):November 2011
DOI:10.1016/j.elecom.2011.09.008
LiMn2O4 nanorods were prepared by a facile hydrothermal method in combination with traditional solid-state reactions and characterized by X-ray diffraction analysis. Their electrochemical behavior was tested by cyclic voltammetry and repeated charge/discharge cycling. Results show that the reversible intercalation/deintercalation of Li-ions into/from LiMn2O4 cathode can yield up to 110 mAh/g at 4.5 C, and still retains 88% at the very large charge rate of 90 C with well-defined charge and discharge plateaus. It presents very high power density, up to 14.5 kW/kg, and very excellent cycling behavior, 94% capacity retention after 1200 cycles. It is thus a competitor for LiFePO4.Highlights► We prepared LiMn2O4 nanorods by hydrothermal method in combination with a solid-state reaction. ► Their reversible intercalation/deintercalation of Li ions can be up to 110 mAh/g at 4.5 C. ► It still keeps 88% of capacity at the very large charge rate of 90C with well-defined charge and discharge plateaus. ► It shows very high power density, up to 14.5 kW/kg, and excellent cycling behavior.
Co-reporter:W. Tang, S. Tian, L.L. Liu, L. Li, H.P. Zhang, Y.B. Yue, Y. Bai, Y.P. Wu, K. Zhu
Electrochemistry Communications 2011 Volume 13(Issue 2) pp:205-208
Publication Date(Web):February 2011
DOI:10.1016/j.elecom.2010.12.015
Nanochain LiMn2O4 was prepared by a starch-assisted sol–gel method. Its electrochemical behavior as a cathode material for aqueous rechargeable lithium batteries (ARLBs) was characterized by cyclic voltaammograph, capacity measurement and cycling test. Results show that the nanochain LiMn2O4 has an ultra-fast charge capability. It presents a reversible capacity of 110 mAh/g at 4.5 C and 95 mAh/g even at 91 C in 0.5 mol/l Li2SO4 aqueous electrolyte. When charged at 136 C, 84% capacity could be obtained. In addition, its cycling behavior is also very good. After 200 cycles at 4.5 C, there is no evident capacity fading.
Co-reporter:L.L. Li, L. Li, B. Wang, L.L. Liu, Y.P. Wu, T. van Ree, K.A. Thavhiwa
Electrochimica Acta 2011 Volume 56(Issue 13) pp:4858-4864
Publication Date(Web):1 May 2011
DOI:10.1016/j.electacta.2011.02.117
Methyl phenyl bis-methoxydiethoxysilane (MPBMDS) was prepared and its effects were investigated as an additive in 1.0 mol dm−3 LiPF6-propylene carbonate (PC)/dimethyl carbonate (DMC) (1:1, v/v) electrolyte for lithium ion batteries. The electrochemical properties of the electrolyte with MPBMDS were characterized by discharge/charge tests, cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The addition of MPBMDS can effectively prevent the decomposition and the co-intercalation of PC. In addition, burning tests showed that the addition of 4–13 wt.% MPBMDS to the bare PC-based electrolyte effectively reduces the flammability. This eco-friendly compound provides a new promising direction for the development of bi- or multi-functional additives for lithium ion batteries.Highlights► Adding MPBMDS to PC-based electrolyte can prevent decomposition and co-intercalation of PC. ► Addition of 4–13 wt.% MPBMDS to bare PC-based electrolyte reduces flammability. ► A stable SEI film is formed on the surface of the CMS electrode.
Co-reporter:W.L. Guo, L. Li, L.L. Li, S. Tian, S.L. Liu, Y.P. Wu
International Journal of Hydrogen Energy 2011 Volume 36(Issue 16) pp:9415-9419
Publication Date(Web):August 2011
DOI:10.1016/j.ijhydene.2011.04.127
Hydrogen was produced via electrolysis of aqueous formic acid solutions, and the effects of the concentrations of formic acid and NaOH on the electrolytic voltage were systematically investigated. The voltage is found to be related to the actual formic acid concentration. When the actual formic acid concentration is higher than 0.8 × 10−9 M, the initial electrolytic voltage can be as low as 0.30 V, which is much lower than the open circuit voltage in a proton exchange membrane fuel cell. The electrolytic voltage increases with the increase of the current density. Specifically at 1.0 M NaOH and 4.0 M HCOOH, the steady voltage value increases from 0.62 to 0.70 V as the current density increases from 1.0 to 6.0 mA/cm2. At 3.0 M HCOOH and 2.5 M NaOH, the hydrogen production rate is 53 μmol/h under 8.0 mA/cm2, which is promising for practical industrial-scale hydrogen production.Highlights► Production of hydrogen via electrolysis of aqueous formic acid solutions is described. ► The initial electrolytic voltage for formic acid solution can be as low as 0.30 V, which is much lower than those for water, methanol and ethanol. ► The electrolytic voltage increases with the increase of the current density. ► At 3.0 M HCOOH and 2.5 M NaOH, the hydrogen production rate is 53 μmol/h under 8.0 mA/cm2, which is promising for practical industrial-scale hydrogen production.
Co-reporter:Lei Li;Wenliang Guo;Yusong Zhu ;Dr. Yuping Wu
ChemSusChem 2011 Volume 4( Issue 10) pp:1475-1480
Publication Date(Web):
DOI:10.1002/cssc.201100167
Abstract
A TiO2/FTO (FTO=fluorine-doped tin oxide) electrode was prepared by dip-coating FTO in a suspension of TiO2 prepared from a sol–gel method and was used as a photoanode to split an aqueous solution of formic acid to produce hydrogen. The surface of the TiO2/FTO film was covered with assemblies of TiO2 nanoparticles with a diameter of approximately 20 nm. Under irradiation by using a Xe lamp, splitting of formic acid was performed at different applied current densities. Compared to splitting water or utilizing FTO and Pt foil as the anode, the splitting voltage is much lower and can be as low as −0.27 V. The results show that the splitting voltage is related to the concentration of free formate groups. The evolution rate of hydrogen measured by using gas chromatography is 130 μmol h−1 at a current density of 20 mA cm−2 and the energy-conversion efficiency can be 1.79 %. Photoelectrolysis of formic acid has the potential to be an efficient way to produce hydrogen with a high energy-conversion efficiency.
Co-reporter:P. Zhang, L.C. Yang, L.L. Li, M.L. Ding, Y.P. Wu, R. Holze
Journal of Membrane Science 2011 379(1–2) pp: 80-85
Publication Date(Web):
DOI:10.1016/j.memsci.2011.05.043
Co-reporter:Qingsheng Gao, Lichun Yang, Xinchun Lu, Jianjiang Mao, Yahong Zhang, Yuping Wu and Yi Tang
Journal of Materials Chemistry A 2010 vol. 20(Issue 14) pp:2807-2812
Publication Date(Web):12 Feb 2010
DOI:10.1039/B921001F
This paper presents a novel strategy to synthesize MoO2/carbon nanowires based on organic–inorganic hybrid nanocomposites with nanometre periodic structures. The organic–inorganic hybrid precursors provide uniform reactions throughout the composites for achieving novel carbon-hybrid structures and nano-morphology via easy calcination. Through the systematic physical characterization including scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, etc., the one-dimensional and carbon-hybrid structure of MoO2/C nanowires was confirmed. This synthetic strategy is also proved universal for other novel MoO2/C nanostructures based on various organic-inorganic hybrid precursors. Furthermore, the MoO2/C hybrid nanowires show good rate capability even at the high current density of 1000 mA g−1 as anode material for lithium ion battery.
Co-reporter:P. Zhang, L.C. Yang, L. Li, Q.T. Qu, Y.P. Wu, M. Shimizu
Journal of Membrane Science 2010 Volume 362(1–2) pp:113-118
Publication Date(Web):15 October 2010
DOI:10.1016/j.memsci.2010.06.024
Effects of different reaction conditions such as temperature, time and amount of the added effervescent disintegrant on the porous structures of the porous polymer membranes prepared by microwave assisted effervescent disintegrable reaction between citric acid and sodium bicarbonate were investigated. Shorter reaction time at higher temperature is beneficial to higher porosity of the membrane. The ionic conductivity of the prepared porous polymer electrolytes based on the porous polymer membranes is up to 1.17 × 10−3 S/cm and their electrochemical window is above 5 V. This method is convenient and will greatly promote the practical application of porous polymer membranes in various areas.Graphical abstractResearch highlights▶ Safety of lithium ion batteries is closely related to electrolytes. ▶ Polymer electrolytes can greatly solve the safety issue. ▶ Costs to produce polymer electrolyte are key issues for commercial application. ▶ Microwave assisted effervescent disintegrable reaction is an effective and practical method.
Co-reporter:Qunting Qu, Lei Li, Shu Tian, Wenling Guo, Yuping Wu, Rudolf Holze
Journal of Power Sources 2010 Volume 195(Issue 9) pp:2789-2794
Publication Date(Web):1 May 2010
DOI:10.1016/j.jpowsour.2009.10.108
Studies of the electrochemical behavior of K0.27MnO2·0.6H2O in K2SO4 show the reversible intercalation/deintercalation of K+-ions in the lattice. An asymmetric supercapacitor activated carbon (AC)/0.5 mol l−1 K2SO4/K0.27MnO2·0.6H2O was assembled and tested successfully. It shows an energy density of 25.3 Wh kg−1 at a power density of 140 W kg−1; at the same time it keeps a very good rate behavior with an energy density of 17.6 Wh kg−1 at a power density of 2 kW kg−1 based on the total mass of the active electrode materials, which is higher than that of AC/0.5 mol l−1 Li2SO4/LiMn2O4. In addition, this asymmetric supercapacitor shows excellent cycling behavior without the need to remove oxygen from the electrolyte solution. This can be ascribed in part to the stability of the lamellar structure of K0.27MnO2·0.6H2O. This asymmetric aqueous capacitor has great promise for practical applications due to high energy density at high power density.
Co-reporter:W. Tang, L.L. Liu, S. Tian, L. Li, Y.B. Yue, Y.P. Wu, S.Y. Guan, K. Zhu
Electrochemistry Communications 2010 Volume 12(Issue 11) pp:1524-1526
Publication Date(Web):November 2010
DOI:10.1016/j.elecom.2010.08.024
Crystalline nanoparticles of LiCoO2 are prepared by a sol–gel method at 550 °C and characterized by X-ray diffraction. Their electrochemical behaviors were characterized by cyclic voltammograms, capacity measurement and cycling performance. Results show that the reversible capacity of the nano-LiCoO2 can be up to 143 mAh/g at 1000 mA/g and still be 133 mAh/g at 10,000 mA/g (about 70C) in 0.5 mol/l Li2SO4 aqueous electrolyte. In addition, their cycling behavior is also very satisfactory, no evident capacity fading during the initial 40 cycles. These data present great promise for the application of aqueous rechargeable lithium batteries.
Co-reporter:L.C. Yang, Q.S. Gao, L. Li, Y. Tang, Y.P. Wu
Electrochemistry Communications 2010 Volume 12(Issue 3) pp:418-421
Publication Date(Web):March 2010
DOI:10.1016/j.elecom.2010.01.008
Mesoporous Ge was prepared by mechanochemical reaction of GeO2 and Mg powders followed by an etching process with HCl solution. It was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and charge–discharge measurement. With a pore-distribution concentrated around 10 nm, the product presents a BET surface area of 49.98 m2/g. When using as an anode material for lithium ion battery, the mesoporous Ge exhibits a reversible capacity of 950 mA h/g and retains a capacity of 789 mA h/g after 20 cycles at a current density of 150 mA/g. The cycleability is significantly improved compared with non-porous Ge.
Co-reporter:N.H. Zhao, L.C. Yang, P. Zhang, G.J. Wang, B. Wang, B.D. Yao, Y.P. Wu
Materials Letters 2010 Volume 64(Issue 8) pp:972-975
Publication Date(Web):30 April 2010
DOI:10.1016/j.matlet.2010.01.077
One-dimensional (1D) SnO2 nanowires, coated by in situ formed amorphous carbon nanotubes (a-CNTs) with a mean diameter of ca. 60 nm, were synthesized by annealing the anodic alumina oxide (AAO) filled with a sol of SnO2. X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns revealed that the prepared SnO2 nanowires exist in polycrystalline rutile structure. The coating of carbon nanotubes has some defects on the wall after the internal SnO2 nanoparticles were removed. The 1D SnO2 nanowires present a reversible capacity of 441 mAh/g and an excellent cycling performance as an anode material for lithium ion batteries. This suggests that 1D nanostructured materials have great promise for practical application.
Co-reporter:G. J. Wang;L. C. Yang;Q. T. Qu;B. Wang
Journal of Solid State Electrochemistry 2010 Volume 14( Issue 5) pp:865-869
Publication Date(Web):2010 May
DOI:10.1007/s10008-009-0869-3
An aqueous rechargeable lithium battery (ARLB) using an electroactive polymer, polypyrrole (PPy), as a negative electrode; a lithium ion intercalation compound LiCoO2 as a positive electrode; and Li2SO4 aqueous solution as an electrolyte and its working mechanism are described. The charge/discharge process is associated with the doping/un-doping of anions at the negative electrode and intercalation/deintercalation of lithium ions at the positive electrode. The average output voltage of the PPy//LiCoO2 battery is about 0.85 V. This battery exhibits excellent cycling performance. This new technology solves the major problem of poor cycling life of ARLBs and will provide a new strategy to explore advanced energy storage and conversion systems.
Co-reporter:Liang Zhou ; Lichun Yang ; Pei Yuan ; Jin Zou ; Yuping Wu ;Chengzhong Yu
The Journal of Physical Chemistry C 2010 Volume 114(Issue 49) pp:21868-21872
Publication Date(Web):November 15, 2010
DOI:10.1021/jp108778v
Flexible single crystalline α-MoO3 nanobelts with widths of 200−500 nm, lengths of 5−10 μm, and thicknesses of ∼50 nm have been prepared by a facile hydrothermal treatment method. When fabricated as the cathode for lithium ion batteries, the as-synthesized α-MoO3 nanobelts exhibit excellent rate capability, large capacity, and good cycling stability. An initial discharge capacity of 176 mAh/g can be obtained at 5000 mA/g, retaining a capacity of 115 mAh/g after 50 cycles. The superior high-rate capability can be attributed to the increased conductivity of the electrode during cycling and the nanobelts morphology. The excellent performance makes the α-MoO3 nanobelts a promising cathode material for rechargeable lithium ion batteries in the application of electronic vehicles and hybrid electronic vehicles.
Co-reporter:G.J. Wang, Q.T. Qu, B. Wang, Y. Shi, S. Tian, Y.P. Wu, R. Holze
Journal of Power Sources 2009 Volume 189(Issue 1) pp:503-506
Publication Date(Web):1 April 2009
DOI:10.1016/j.jpowsour.2008.11.006
Electrochemical intercalation of lithium ions from a saturated LiNO3 aqueous electrolyte solution into LiV3O8 prepared by a solid-state reaction at 680 °C was studied with cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Results show that there are three steps of intercalation in the presence of an aqueous electrolyte, in agreement with those previously observed with organic liquid electrolytes. In addition, variations of several parameters including the charge transfer resistance (Rct), the capacitance of the double layer (CDL), the Warburg diffusion impedance (Zw), and diffusion coefficient of lithium ions (DLi+DLi+) during the intercalation process are reported.
Co-reporter:Q.T. Qu, Y. Shi, S. Tian, Y.H. Chen, Y.P. Wu, R. Holze
Journal of Power Sources 2009 Volume 194(Issue 2) pp:1222-1225
Publication Date(Web):1 December 2009
DOI:10.1016/j.jpowsour.2009.06.068
A new cheap asymmetric supercapacitor based on activated carbon (AC) and NaMnO2 as electrodes and aqueous Na2SO4 solution as electrolyte was assembled. It shows an energy density of 19.5 Wh kg−1 at a power density of 130 W kg−1 based on the total mass of the active electrode materials and an excellent cycling behavior. This asymmetric aqueous AC//NaMnO2 capacitor is promising for practical applications due to its low price, easy preparation of NaMnO2 and friendliness to environment.
Co-reporter:P. Zhang, G.C. Li, H.P. Zhang, L.C. Yang, Y.P. Wu
Electrochemistry Communications 2009 Volume 11(Issue 1) pp:161-164
Publication Date(Web):January 2009
DOI:10.1016/j.elecom.2008.11.002
Porous polymer membranes with sub-micrometer pores were successfully prepared by a novel microwave assisted effervescent disintegrable reaction. The fine connected porous structure was obtained by promoting effervescent disintegrable reaction between citric acid and sodium bicarbonate due to the assistance of microwave. The ionic conductivity of the prepared gelled polymer electrolyte is up to 1.17 × 10−3 S cm−1 and electrochemical window 4.5 V. This method provides a convenient route to prepare porous polymer electrolyte, which will greatly promote the practical application of porous polymer electrolytes.
Co-reporter:Z.B. Wen, Q.T. Qu, Q. Gao, X.W. Zheng, Z.H. Hu, Y.P. Wu, Y.F. Liu, X.J. Wang
Electrochemistry Communications 2009 Volume 11(Issue 3) pp:715-718
Publication Date(Web):March 2009
DOI:10.1016/j.elecom.2009.01.015
A polymeric activated carbon (PAC) was synthesized from the carbonization of a resorcinol–formaldehyde resin with KOH served as an activation agent. The nitrogen adsorption–desorption at 77 K, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared PAC. Compared with the commercial activated carbon (Maxsorb: Kansai, Japan), PAC shows superior capacitive performance in terms of specific capacitance, power output and high energy density as electrode materials for supercapacitors. PAC presents a high specific capacitance of 500 F g−1 in 6 mol l−1 KOH electrolyte at a current density of 233 mA g−1 which remained 302 F g−1 even at a high current density of 4.6 A g−1. The good electrochemical performance of the PAC was ascribed to well-developed micropores smaller than 1.5 nm, the presence of electrochemically oxygen functional groups and low equivalent series resistance.
Co-reporter:Q.T. Qu, Y. Shi, L.L. Li, W.L. Guo, Y.P. Wu, H.P. Zhang, S.Y. Guan, R. Holze
Electrochemistry Communications 2009 Volume 11(Issue 6) pp:1325-1328
Publication Date(Web):June 2009
DOI:10.1016/j.elecom.2009.05.003
V2O5·0.6H2O nanoribbons were prepared and their electrochemical behaviors in K2SO4 aqueous solution were investigated. Results show for the first time that K+ ions could intercalate/deintercalate reversibly in the V2O5·0.6H2O lattice. An asymmetric supercapacitor activated carbon/0.5 mol/l K2SO4/V2O5·0.6H2O was successfully assembled, which could be cycled reversibly in the voltage region of 0–1.8 V. This supercapacitor presents an energy density of 29.0 Wh/kg based on the total mass of the active electrode materials, a very good rate behavior with energy density of 20.3 Wh/kg at power density of 2 kW/kg, and also a rather good cycling performance.
Co-reporter:Z.H. Li, C. Cheng, X.Y. Zhan, Y.P. Wu, X.D. Zhou
Electrochimica Acta 2009 Volume 54(Issue 18) pp:4403-4407
Publication Date(Web):15 July 2009
DOI:10.1016/j.electacta.2009.03.016
A foaming process was used to prepare porous polymer membranes (PPMs) based on poly(vinylidene diflouride-co-hexafluoropropylene) copolymer for lithium ion batteries. In this simple process, urea, the foaming agent, was decomposed into gases and was removed at an elevated temperature to get the porous structure within the polymer matrix. When the weight ratio of urea to P(VDF-HFP) is 5:6, the PPM presents the highest porosity, 70.2%, and the prepared gelled polymer electrolyte shows an ionic conductivity up to 1.43 × 10−3 S cm−1 at room temperature. This provides another way to prepare gelled polymer electrolytes easily for application in rechargeable lithium batteries.
Co-reporter:G.J. Wang, Q.T. Qu, B. Wang, Y. Shi, S. Tian, Y.P. Wu, R. Holze
Electrochimica Acta 2009 Volume 54(Issue 4) pp:1199-1203
Publication Date(Web):30 January 2009
DOI:10.1016/j.electacta.2008.08.047
The electrochemical behavior of a commercial LiCoO2 with spherical shape in a saturated Li2SO4 aqueous solution was investigated with cyclic voltammetry and electrochemical impedance spectroscopy. Three redox couples at ESCE = 0.87/0.71, 0.95/0.90 and 1.06/1.01 V corresponding to those found at ELi/Li+=4.08/3.83ELi/Li+=4.08/3.83, 4.13/4.03 and 4.21/4.14 V in organic electrolyte solutions were observed. The diffusion coefficient of lithium ions is 1.649 × 10−10 cm2 s−1, close to the value in organic electrolyte solutions. The results indicate that the intercalation and deintercalation behavior of lithium ions in the Li2SO4 solution is similar to that in the organic electrolyte solutions. However, due to the higher ionic conductivity of the aqueous solution, current response and reversibility of redox behavior in the aqueous solution are better than in the organic electrolyte solutions, suggesting that the aqueous solution is favorable for high rate capability. The charge transfer resistance, the exchange current and the capacitance of the double layer vary with the charge voltage during the deintercalation process. At the peak of the oxidation (0.87 V), the charge transfer resistance is the lowest. These fundamental results provide a good base for exploring new safe power sources for large scale energy storage.
Co-reporter:L.J. Fu, L.C. Yang, Y. Shi, B. Wang, Y.P. Wu
Microporous and Mesoporous Materials 2009 Volume 117(1–2) pp:515-518
Publication Date(Web):1 January 2009
DOI:10.1016/j.micromeso.2008.07.008
Carbon coated nanoporous TiO2 was prepared by calcining the nano polystyrene template filling with TiO2 precursor in the air followed by dipping into a sucrose solution and heat-treating in argon atmosphere. The synthesized composite presents an interconnected conductive carbon architecture, which is favourable for the transportation of lithium ions and electrons during cycling. In addition, the nano carbon coating can keep the structural stability of TiO2 during cycling. As a result, at high discharge and charge rates the polarization is decreased, the reversible capacity and the coulomb efficiency in the first cycle are increased, and excellent cycling performance in combination of good rate capability has been achieved. This strategy to synthesize conductive carbon coated nanoporous materials will be helpful for the further development of electrode material for lithium ion batteries, presenting their potential application in electric vehicles.
Co-reporter:N.H. Zhao, P. Zhang, L.C. Yang, L.J. Fu, B. Wang, Y.P. Wu
Materials Letters 2009 Volume 63(Issue 22) pp:1955-1957
Publication Date(Web):15 September 2009
DOI:10.1016/j.matlet.2009.06.016
An easy versatile method is reported to synthesize tunable amorphous carbon nanotubes (a-CNTs) with different pore diameter, length and orientation of graphene layers at a low temperature of 450 °C in the absence of metal catalysts by using porous anodic aluminum oxide (AAO) as a template and citric acid as a precursor. Since citric acid was adsorbed by hydrogen bonds with the –OH groups at the walls of the AAO templates, which can be influenced by the concentration of H+ ions in the solution, the pH leads to the change of the orientation of graphene layers and the graphitization degree.
Co-reporter:P. Zhang;H. P. Zhang;Z. H. Li;Y. P. Wu;T. van Ree
Polymers for Advanced Technologies 2009 Volume 20( Issue 6) pp:571-575
Publication Date(Web):
DOI:10.1002/pat.1385
Abstract
Composite polymer electrolytes (CPE) for lithium ion batteries are reported. Initially, nano-TiO2 was modified by coating with a layer of poly(methyl methacrylate) (PMMA) by emulsion polymerization. CPE with this modified nano-TiO2 were then prepared by the in situ copolymerization of poly(methyl methacrylate-acrylonitrile) (P(MMA-AN)). Morphology, thermal, electrochemical, and spectroscopic measurements were used to characterize the electrolytes. The PMMA-coated nano-TiO2 was well dispersed in the polymer matrix due to the PMMA coating layer making the nanoparticles hydrophobic to effectively avoid the aggregation of the nanoparticles. The homogeneous CPEs of this PMMA-coated nano-TiO2 have better thermal tolerance, higher ionic conductivity, and wider electrochemical stability, thus providing a practical route to improved polymer electrolytes. Copyright © 2009 John Wiley & Sons, Ltd.
Co-reporter:Qunting Qu, Peng Zhang, Bin Wang, Yuhui Chen, Shu Tian, Yuping Wu and Rudolf Holze
The Journal of Physical Chemistry C 2009 Volume 113(Issue 31) pp:14020-14027
Publication Date(Web):July 14, 2009
DOI:10.1021/jp8113094
The electrochemical performance of MnO2 nanorods prepared by a precipitation reaction was investigated in 0.5 mol/L Li2SO4, Na2SO4, and K2SO4 aqueous electrolyte solutions. Results show that at the slow scan rates, the nanorods show the largest capacitance (201 F/g) in Li2SO4 electrolyte since the reversible intercalation/deintercalation of Li+ in the solid phase produces an additional capacitance besides the capacitance based on the absorption/desorption reaction. At fast scan rates they show the largest capacitance in the K2SO4 electrolyte due to the smallest hydration radius of K+, highest ionic conductivity, and lowest equivalent series resistance (ESR). An asymmetric activated carbon (AC)/K2SO4/MnO2 supercapacitor could be cycled reversibly between 0 and 1.8 V with an energy density of 17 Wh/kg at 2 kW/kg, much higher than those of the AC/K2SO4/AC supercapacitor and AC/Li2SO4/LiMn2O4 hybrid supercapacitor. Moreover, this supercapacitor exhibits excellent cycling behavior with no more than 6% capacitance loss after 23 000 cycles at 10C rate even when the dissolved oxygen is not removed.
Co-reporter:Nahong Zhao, Gaojun Wang, Yan Huang, Bin Wang, Baodian Yao and Yuping Wu
Chemistry of Materials 2008 Volume 20(Issue 8) pp:2612
Publication Date(Web):March 18, 2008
DOI:10.1021/cm703353y
Co-reporter:Z.H. Li, H.P. Zhang, P. Zhang, G.C. Li, Y.P. Wu, X.D. Zhou
Journal of Membrane Science 2008 Volume 322(Issue 2) pp:416-422
Publication Date(Web):15 September 2008
DOI:10.1016/j.memsci.2008.05.074
A kind of porous nanocomposite polymer membranes (NCPMs) based on poly(vinylidene difluoride-co-hexafluoropropylene) (P(VdF-HFP)) incorporated with different amounts of TiO2 nanoparticles from in situ hydrolysis of Ti(OC4H9)4 was prepared by a non-solvent induced phase separation (NIPS) technology. The SEM micrographs reveal that a porous structure exists in the NCPMs, which changes with the incorporated amount of TiO2. The NCPMs incorporated with 9.0 wt.% of mass fraction of TiO2 possess the highest porosity, 67.3%, and appear as flexile fracture with an elongation ratio, 74.4%. At this content, the ionic conductivity of the NCPE is up to 0.94 × 10−3 S cm−1 at room temperature and the activation energy for ions transport reaches the lowest, 18.71 kJ mol−1. It is of great potential application in lithium ion batteries.
Co-reporter:L.C. Yang, Q.S. Gao, Y. Tang, Y.P. Wu, R. Holze
Journal of Power Sources 2008 Volume 179(Issue 1) pp:357-360
Publication Date(Web):15 April 2008
DOI:10.1016/j.jpowsour.2007.12.099
MoO2 synthesized through reduction of MoO3 with ethanol vapor at 400 °C was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Its electrochemical performance as an anode material for lithium ion battery was tested by cyclic voltammetry (CV) and capacity measurements. During the reduction process, the starting material (MoO3) collapsed into nanoparticles (∼100 nm), on the nanoparticles remains a carbon layer from ethanol decomposition. Rate capacity and cycling performance of the as-prepared product is very satisfactory. It displays 318 mAh g−1 in the initial charge process with capacity retention of 100% after 20 cycles in the range of 0.01–3.00 V vs. lithium metal at a current density of 5.0 mA cm−2, and around 85% of the retrievable capacity is in the range of 1.00–2.00 V. This suggests the application of this type of MoO2 as anode material in lithium ion batteries.
Co-reporter:Z.H. Li, H.P. Zhang, P. Zhang, Y.P. Wu, X.D. Zhou
Journal of Power Sources 2008 Volume 184(Issue 2) pp:562-565
Publication Date(Web):1 October 2008
DOI:10.1016/j.jpowsour.2008.02.068
A novel macroporous nanocomposite polymer membrane (NCPM) based on poly(vinylidene difluoride-co-hexafluoropropylene) [P(VDF-HFP)] copolymer was prepared by in situ hydrolysis of Ti(OC4H9)4 using a non-solvent-induced phase separation technique. SEM micrograph shows that the yielding TiO2 nanoparticles are dispersed uniformly in the polymer matrix and there are a lot of spherical macropores connecting with each other by some smaller pores. DSC results exhibit that the crystallinity of polymer matrix decreases with the incorporation of TiO2 nanoparticles. The tensile stress of the NCPM is 9.69 MPa and its fracture strain 74.4%. After immersion in 1.0 mol l−1 LiPF6/ethyl carbonate (EC)–dimethyl carbonate (DMC), the ionic conductivity of the obtained nanocomposite polymer electrolyte (NCPE) is 0.98 × 10−3 S cm−1 at 20 °C. Lithium-ion batteries, which use this kind of NCPE as the separator and electrolyte, display good discharging performance at different current densities, presenting promise for its practical application.
Co-reporter:T. Zhang, H.P. Zhang, L.C. Yang, B. Wang, Y.P. Wu, T. Takamura
Electrochimica Acta 2008 Volume 53(Issue 18) pp:5660-5664
Publication Date(Web):20 July 2008
DOI:10.1016/j.electacta.2008.03.017
The silicon film (6 μm) was prepared by vacuum deposition method on a surface modified copper foil as anode for lithium-ion batteries with high capacity and long cycle life. The modified copper foil has a rough and pyramid-like surface which helps the deposited Si film to connect toughly. The deposited hill-like Si is favorable to reduce the mechanical stress coming from the volume expansion and shrinkage of active materials during lithiation and de-lithiation. Moreover, the Si film exists mostly in an amorphous state. After cycling, partial amorphous phase transforms into the polycrystalline Si grains, forming a combination of amorphous and crystalline structure. Cyclic voltammograms (CVs) and electrochemical impedance spectra (EIS) research indicate that the vacuum-deposited thick Si film has a good reversibility of lithiation/de-lithiation. As a consequence, the thick Si film exhibits an excellent cycling performance with high reversible capacity.
Co-reporter:J. Gao, L.J. Fu, H.P. Zhang, L.C. Yang, Y.P. Wu
Electrochimica Acta 2008 Volume 53(Issue 5) pp:2376-2379
Publication Date(Web):1 January 2008
DOI:10.1016/j.electacta.2007.09.058
Graphitic carbon was coated with nano-TiO2 by a simple mechanical process. X-ray diffraction and scanning electron microscopy were used to measure the crystal structure and surface morphology of the coated composite. Tests of galvanostatic discharge and charge and cyclic voltammograms suggest that the decomposition of propylene carbonate and the exfoliation of graphite are greatly suppressed. Lithium ions can reversibly intercalate into and deintercalate from the TiO2-coated graphite, and quite stable cycling behavior in propylene carbonate-based electrolyte is achieved.
Co-reporter:Gaojun Wang ;Qunting Qu Dr.;Bin Wang Dr.;Yi Shi;Shu Tian
ChemPhysChem 2008 Volume 9( Issue 16) pp:2299-2301
Publication Date(Web):
DOI:10.1002/cphc.200800424
Co-reporter:Z. H. Li;H. P. Zhang;P. Zhang;Y. P. Wu
Journal of Applied Electrochemistry 2008 Volume 38( Issue 1) pp:109-114
Publication Date(Web):2008 January
DOI:10.1007/s10800-007-9407-0
A micro-porous composite polymer electrolyte (MCPE) was prepared in situ by adding TiO2 nanoparticles from the hydrolysis of titanium tetrabutoxide to a solution of poly(vinylidenefluoride-co-hexafluoropropylene) [P(VDF-HFP)] copolymer. The prepared microporous polymer films (MCPFs) were characterized by scanning electronic microscopy, X-ray diffraction, thermogravimetric analysis, FT-IR and electrochemical interface resistance. After the addition of TiO2 nanoparticles the polarity of CF2 groups in the polymer chains and the crystallinity of the MCPFs decreased. When the composite polymer film contained 8.5 wt% of TiO2 nanoparticles the MCPE exhibited excellent electrochemical properties such as high ionic conductivity, up to 2.40 × 10−3 S cm−1 at room temperature.
Co-reporter:G. J. Wang;L. J. Fu;B. Wang;N. H. Zhao;Y. P. Wu
Journal of Applied Electrochemistry 2008 Volume 38( Issue 4) pp:579-581
Publication Date(Web):2008 April
DOI:10.1007/s10800-007-9469-z
Co-reporter:J. Gao, H.P. Zhang, L.J. Fu, T. Zhang, Y.P. Wu, T. Takamura, H.Q. Wu, R. Holze
Electrochimica Acta 2007 Volume 53(Issue 3) pp:1380-1384
Publication Date(Web):20 December 2007
DOI:10.1016/j.electacta.2007.10.008
A method has been developed to suppress the decomposition of propylene carbonate (PC) by coating graphite electrode foil with a layer of silver. Results from electrochemical impedance measurements show that the Ag-coated graphite electrode presents lower charge transfer resistance and faster diffusion of lithium ions in comparison with the virginal one. Cyclic voltammograms and discharge–charge measurements suggest that the decomposition of propylene carbonate and co-intercalation of solvated lithium ions are prevented, and lithium ions can reversibly intercalate into and deintercalate from the Ag-coated graphite electrode. These results indicate that Ag-coating is a good way to improve the electrochemical performance of graphitic carbon in PC-based electrolyte solutions.
Co-reporter:J. Gao, H.P. Zhang, L.J. Fu, T. Zhang, Y.P. Wu, T. Takamura, H.Q. Wu, R. Holze
Electrochimica Acta 2007 Volume 52(Issue 17) pp:5417-5421
Publication Date(Web):5 May 2007
DOI:10.1016/j.electacta.2007.02.064
A method has been developed to suppress the decomposition of propylene carbonate (PC) by coating graphite electrode foil with a layer of silver. Results from electrochemical impedance measurements show that the Ag-coated graphite electrode presents lower charge transfer resistance and faster diffusion of lithium ions in comparison with the virginal one. Cyclic voltammograms and discharge–charge measurements suggest that the decomposition of propylene carbonate and co-intercalation of solvated lithium ions are prevented, and lithium ions can reversibly intercalate into and deintercalate from the Ag-coated graphite electrode. These results indicate that Ag-coating is a good way to improve the electrochemical performance of graphitic carbon in PC-based electrolyte solutions.
Co-reporter:Gaojun Wang;Lijun Fu;Nahong Zhao;Lichun Yang ;Haoqing Wu
Angewandte Chemie 2007 Volume 119(Issue 1‐2) pp:
Publication Date(Web):28 NOV 2006
DOI:10.1002/ange.200603699
„Grüne Batterien“: Die Zahl der Auf- und Entladungen einer wässrigen, wiederaufladbaren Lithiumbatterie (ARLB) mit einer Sekundärspannung von 1.05 V wird durch geeignete Intercalationsverbindungen als Elektrodenmaterialien merklich erhöht (siehe Diagramm). Dieses System ist prinzipiell sehr stabil und bietet eine Möglichkeit zur Erforschung von Systemen zur Energiespeicherung und -umwandlung, besonders solcher für künftige Elektrofahrzeuge.
Co-reporter:Gaojun Wang;Lijun Fu;Nahong Zhao;Lichun Yang ;Haoqing Wu
Angewandte Chemie International Edition 2007 Volume 46(Issue 1‐2) pp:
Publication Date(Web):28 NOV 2006
DOI:10.1002/anie.200603699
“Green” batteries: The cycling of an aqueous rechargeable lithium battery (ARLB) with an output voltage of 1.05 V is markedly improved by choosing the appropriate intercalation compounds as electrode materials (see diagram). This system is, in principle, very stable and provides a means to explore new energy-storage and conversion systems, especially for use in future electric vehicles.
Co-reporter:X. J. Wang;H. P. Zhang;J. J. Kang;Y. P. Wu
Journal of Solid State Electrochemistry 2007 Volume 11( Issue 1) pp:21-26
Publication Date(Web):2007 January
DOI:10.1007/s10008-005-0029-3
Novel composite solid polymer electrolytes (CSPEs) and composite gel polymer electrolytes (CGPEs) have been prepared. CSPE consists of poly(ether-urethane) network polymer (PUN), fumed silicas and LiClO4. The ionic conductivity of CSPEs can be enhanced nearly 20 times in comparison with the plain system without the addition of fumed silicas and can be above 1×10−5 S/cm at room temperature. The effects of both kinds of fumed silicas, viz. uSiO2 with hydrophilic groups at the surface and mSiO2 with hydrophobic groups at the surface on ionic conductivity were investigated. CGPE comprising of the CSPE and LiClO4–PC solution with good mechanical strength exhibits ionic conductivity in the order of 10−3 S/cm at room temperature and above 3×10−4 S/cm at low temperature −40 °C.
Co-reporter:L.J. Fu, K. Endo, K. Sekine, T. Takamura, Y.P. Wu, H.Q. Wu
Journal of Power Sources 2006 Volume 162(Issue 1) pp:663-666
Publication Date(Web):8 November 2006
DOI:10.1016/j.jpowsour.2006.02.108
It is of great importance to improve the electrochemical performance of graphitic anode materials since they are dominantly used in practical lithium ion battery and still will be the main component as anode material in the future. By SEM, XPS, Micro-Raman and EDX analyses of graphite electrodes before and after discharge/charge cycle, it is found that capacity fading is strongly related to the dispersion of conductive. Homogeneous dispersion of conductive resulted in good cycle performance. However, for the poorly fabricated electrode, with heterogeneous dispersion of conductive, it gives rise to the formation of imperfect SEI film in the first cycle and subsequent continual decomposition of the electrolyte, leading to large amounts of nonconductive surface deposits consisting of Li2CO3 and LiF. As a result, its irreversible capacity is high and capacity retention is poor. Thus, homogeneous dispersion of conductive is necessary to obtain good performance for graphitic anode electrode. The formation of Li2CO3 and LiF during repeated cycling is attributed to the inhomogeneous distribution of the overpotential throughout the fabricated electrode.
Co-reporter:C. Li, H.P. Zhang, L.J. Fu, H. Liu, Y.P. Wu, E. Rahm, R. Holze, H.Q. Wu
Electrochimica Acta 2006 Volume 51(Issue 19) pp:3872-3883
Publication Date(Web):20 May 2006
DOI:10.1016/j.electacta.2005.11.015
Recent research results confirm the importance of structural surface features of cathode materials for their electrochemical performance. Modification by coating is an important method to achieve improved electrochemical performance, and the latest progress was reviewed here. When the surface of cathode materials including LiCoO2, LiNiO2, LiMn2O4 and LiMnO2 is coated with oxides such as MgO, Al2O3, SiO2, TiO2, ZnO, SnO2, ZrO2, Li2O·2B2O3-glass and other materials, the coatings prevent the direct contact with the electrolyte solution, suppress phase transition, improve the structural stability, and decrease the disorder of cations in crystal sites. As a result, side reactions and heat generation during cycling are decreased. Accompanying actions such as suppression of Mn2+ dissolution, increase in conductivity and removal of HF in electrolyte solutions have been observed. Consequently, marked improvement of electrochemical performance of electrode materials including reversible capacity, coulomb efficiency in the first cycle, cycling behavior, rate capability and overcharge tolerance has been achieved. In conclusion, further directions are suggested for the surface modification of electrode materials. With further understanding of the effects of the surface structure of cathode materials on lithium intercalation and de-intercalation, better and/or cheaper cathode materials from surface modification will come up in the near future.
Co-reporter:L.J. Fu, H. Liu, H.P. Zhang, C. Li, T. Zhang, Y.P. Wu, R. Holze, H.Q. Wu
Electrochemistry Communications 2006 Volume 8(Issue 1) pp:1-4
Publication Date(Web):January 2006
DOI:10.1016/j.elecom.2005.10.006
A new and effective method to prepare TiO2/C core–shell nanocomposites as active anode materials for lithium ion batteries with markedly ameliorated electrochemical performance is described. Initially a precursor, polyacrylonitrile coated nano-TiO2 particles, is formed by emulsion polymerization. This precursor is heat-treated under argon atmosphere to achieve the nanocomposite. The conductive carbon shell enveloped TiO2 nanoparticles and suppressed the aggregation of the core nanoparticles during cycling. In addition it is attached closely to the nano-cores, and the kinetics of lithium intercalation and de-intercalation, the apparent diffusion coefficient of lithium ions and the consequent cycling behavior are significantly enhanced. This provides a good way to improve cycling and kinetics of nano-anode materials.
Co-reporter:J. Gao;L. C. Yang;M. Xu;L. J. Fu;W. J. Liu;Y. P. Wu;R. Holze
Polymers for Advanced Technologies 2006 Volume 17(Issue 7‐8) pp:587-590
Publication Date(Web):7 AUG 2006
DOI:10.1002/pat.759
A new composite anode material of Ag and polymeric carbon was prepared by heat-treating the mixture of polyacrylonitrile and AgNO3. They were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS) and electrochemical measurements. It was found that the addition of Ag was favorable for the improvement of electrochemical performance of the composite in comparison with the virginal polymeric carbon. These improvements were due to an increase of electronic conductivity, alloying of lithium with Ag and smaller particle size of the composites. The optimal amount of Ag addition is 5% based on the molar ratio of the monomer unit. Copyright © 2006 John Wiley & Sons, Ltd.
Co-reporter:L.J. Fu, H. Liu, C. Li, Y.P. Wu, E. Rahm, R. Holze, H.Q. Wu
Progress in Materials Science 2005 Volume 50(Issue 7) pp:881-928
Publication Date(Web):September 2005
DOI:10.1016/j.pmatsci.2005.04.002
Since the commercialization of lithium secondary batteries in the early of 1990s, their development has been rapid. Nowadays, improving the preparation technology and electrochemical performance of their electrode materials is a major focus in research and development of the materials, power sources and chemistry. Sol–gel methods are a promising way to prepare electrode materials due to their evident advantages over traditional methods, for example, homogeneous mixing at the atomic or molecular level, lower synthesis temperature, shorter heating time, better crystallinity, uniform particle distribution and smaller particle size at nanometer level. In this paper, latest progress in the preparation of electrode materials by sol–gel methods is reviewed, including cathodic ones, e.g., lithium cobalt oxides, lithium nickel oxides, spinel and layered lithium manganese oxides, vanadium oxides and ferrous phosphates, and anodic ones, e.g., tin oxides and titanium oxides. Compared with those prepared by traditional solid-state reaction, the structure stability of the prepared electrode materials and the behavior of lithium intercalation and de-intercalation are much improved. As a result, the prepared products provide better electrochemical performance including reversible capacity, cycling behavior and rate capability. In addition, sol–gel methods can be used to prepare new kinds of electrode materials such as nanowires of LiCoO2 and nanotubes of V2O5, which cannot be easily created by the traditional methods. Further development and application of sol–gel methods will bring about new and better electrode materials, meaning a great promotion to lithium secondary batteries.
Co-reporter:Lei Zhou, Mingyan Zhang, Yanfang Wang, Yusong Zhu, Lijun Fu, Xiang Liu, Yuping Wu, Wei Huang
Electrochimica Acta (1 April 2017) Volume 232() pp:
Publication Date(Web):1 April 2017
DOI:10.1016/j.electacta.2017.02.096
•The PB electrode delivers excellent rate and cycling capability in 0.5 mol l−1 K2SO4 electrolyte solution.•The hybrid K-ion capacitor (KIC) is assembled based on activated carbon and high quality cubic Prussian blue in K2SO4 electrolyte solution.•The KIC exhibits excellent cycling stability without apparent capacity fading over 1200 cycles.•The KIC given an energy density as high as 28 Wh kg−1.Cubic Prussian blue (PB) crystals are prepared by a facile one-step synsthesis. The structure and morphology of the as-prepared samples are characterized by X-ray power diffraction, inductively coupled plasma, scanning electron microscopy and electrochemical measurement. The PB electrode exhibits superior electrochemical behavior in K2SO4 aqueous solution including high reversible capacity (80 mAh g−1 at the current density of 0.5 A g−1), outstanding rate capability and good cycling stability. The K-ion capacitor (KIC) is also fabricated by using PB as a positive electrode and commercial activated carbon as an negative electrode, and it presents a maximum energy density of 28 Wh kg−1 at the current density of 1 A g−1 (corresponding to 7.5 mA cm−2). Furthermore, the KIC also exhibits excellent cycling stability at the current density of 2 A g−1 with capacity retention of nearly 98% over 1200 cycles. Our synthesized electrode material provides a new way for fabricating high performance electrode materials for superior KIC.A KIC was fabricated by employing a Prussian blue positive electrode and an activated carbon negative electrode in K2SO4 aqueous electrolyte.
Co-reporter:Yanfang Wang, Bingwei Chen, Zheng Chang, Xiaowei Wang, Faxing Wang, Lixin Zhang, Yusong Zhu, Lijun Fu and Yuping Wu
Journal of Materials Chemistry A 2017 - vol. 5(Issue 19) pp:NaN8988-8988
Publication Date(Web):2017/04/10
DOI:10.1039/C7TA01500C
Metal sulfides (MSs) should be feasible candidates for hybrid electrochemical capacitors (HECs) due to their high theoretical specific capacitances. However, their performances are largely hampered by sluggish ion/electron transport kinetics and fast capacitance fading. Here, we provide a new approach to fabricate high-performance dual-structural MSs for long-life electrochemical energy storage devices. With robust, graphitic and nitrogen-doped porous carbon shells and highly conductive reduced graphene oxide (RGO) substrates, our cobalt sulfide-based composite shows 99.7% capacitance retention after 4000 cycles. We also present a sandwich-like carbon electrode with ultrahigh specific capacitance and excellent cycling stability. As a result, a quasi-solid-state HEC comprising the above-mentioned electrodes and a PVA–PAA membrane is fabricated. Its electrochemical performance is superior to those formerly reported for MSs, and our results for the first time provide a solid base for the application of MSs in HECs.
Co-reporter:Baihe Zhang, Yu Liu, Xiongwei Wu, Yaqiong Yang, Zheng Chang, Zubiao Wen and Yuping Wu
Chemical Communications 2014 - vol. 50(Issue 10) pp:NaN1211-1211
Publication Date(Web):2013/11/25
DOI:10.1039/C3CC48382G
An aqueous rechargeable battery system is assembled by using metallic zinc and Na0.95MnO2 as the negative and positive electrodes, respectively. It is cheap and environmentally friendly, and its energy density is 78 Wh kg−1. Its cycling performance is very good with only 8% capacity loss after 1000 cycles at 4 C between 1 and 2 V.
Co-reporter:Xujiong Wang, Qunting Qu, Yuyang Hou, Faxing Wang and Yuping Wu
Chemical Communications 2013 - vol. 49(Issue 55) pp:NaN6181-6181
Publication Date(Web):2013/05/17
DOI:10.1039/C3CC42676A
Using a coated Li metal as an anode and LiCoO2 as a cathode, an aqueous rechargeable battery is built up, whose average discharge voltage is 3.70 V. This high voltage stability is due to the “cross-over” effect of Li+ ions, which is different from the traditional ways of increasing overpotentials. The total energy density can be 465 W h kg−1.
Co-reporter:Faxing Wang, Zheng Chang, Xiaowei Wang, Yanfang Wang, Binwei Chen, Yusong Zhu and Yuping Wu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 9) pp:NaN4845-4845
Publication Date(Web):2015/01/19
DOI:10.1039/C4TA06309K
The core–shell structure of Co3O4@Li2MnO3 was prepared by a facile hydrothermal method following heat treatment at 300 °C. The outer shell is porous and makes the diffusion of Li+ ions to the inner shell easier. The synergetic effect between the core and shell shows that the Co3O4 shell in the composite serves as a host to react with lithium oxide removed from the Li2MnO3 core during the initial charging process, which eliminates the huge irreversible capacity loss of Li2MnO3. As the cathode material for lithium ion batteries, the composite exhibits an attractive discharge capacity of 178 mA h g−1 with little irreversible capacity loss in the voltage range of 2.0–4.8 V. Its cycling performance is stable without any drastic capacity fading when cycling in the high voltage range of 2.0–4.6 V.
Co-reporter:Lei Zhu, Yang Liu, Wenyi Wu, Xiongwei Wu, Weiping Tang and Yuping Wu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 29) pp:NaN15162-15162
Publication Date(Web):2015/06/11
DOI:10.1039/C5TA02529J
LiNi0.8Co0.15Al0.05O2 is considered as an alternative to the commercial LiCoO2 positive electrode material for lithium ion batteries because of its excellent cycling performance. However, its capacity fading and potential safety hazard still need to be improved. In this study, fluorination has been introduced for the first time to modify the surface of LiNi0.8Co0.15Al0.05O2 by a one-step facile and dry method. The crystalline structure, morphology, surface information and electrochemical performance were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectronic spectroscopy and electrochemical tests. The surface-fluorinated LiNi0.8Co0.15Al0.05O2 exhibits a reversible capacitance up to 220.5 mA h g−1 at 0.1 C, good rate capability, and an excellent long-term cycling stability with 93.6% capacity retention after 80 cycles at 0.1 C, which is much better than that of the pristine commercial LiNi0.8Co0.15Al0.05O2. The main reason is that metal-fluorine (M–F) bond partially replaces the metal–oxygen (M–O) bond at the surface, enhancing the entire bond energy as well as the structure stability. In addition, the interfacial conductivity between the electrolyte and the positive electrode has been increased, leading to a faster kinetic process. These results show that fluorinated LiNi0.8Co0.15Al0.05O2 is a promising positive electrode material for high performance lithium ion batteries.
Co-reporter:Zheng Chang, Yaqiong Yang, Minxia Li, Xiaowei Wang and Yuping Wu
Journal of Materials Chemistry A 2014 - vol. 2(Issue 28) pp:NaN10755-10755
Publication Date(Web):2014/02/28
DOI:10.1039/C4TA00565A
Widespread use of fossil fuels has resulted in many environmental problems. There is an urgent need to search for reliable green energy storage technologies. The electrical energy storage systems based on neutral aqueous solutions are attractive candidates compared to the present energy storage systems utilizing flammable and expensive organic electrolytes because of their improved safety, low cost and environmental friendliness. What is more, high-rate performance can be achieved due to the high ionic conductivity of the aqueous electrolytes. However, the lower electrochemical window of water limits the possible high output voltage and high energy density. Recently, many new concepts based on neutral aqueous energy storage chemistries including aqueous rechargeable batteries and supercapacitors have exhibited high power and energy densities, excellent cycling life and high Coulombic efficiency. The present paper reviews the latest advances in these new chemistries based on neutral aqueous electrolytes, and the challenges and outlooks in this field are briefly commented on and discussed.
Co-reporter:Bin Wang, Jianli Cheng, Yuping Wu, Dan Wang and Dannong He
Journal of Materials Chemistry A 2013 - vol. 1(Issue 4) pp:NaN1373-1373
Publication Date(Web):2012/11/08
DOI:10.1039/C2TA00487A
Carbon fibers with in situ incorporation of nickel were prepared by electrospinning a solution of a polyacrylonitrile dissolved in a dimethylformamide solution with nickel nitrate, followed by thermal treatment. The prepared one-dimensional composite fibers are uniformly dispersed with an electronic conducting Ni network. As an anode material for lithium-ion batteries, their electrochemical behaviors were measured by cyclic voltammetry, constant current density testing and electrochemical impedance spectroscopy. The carbon/Ni fiber electrode maintains a high reversible capacity of about 457 mA h g−1 after 50 cycles. When tested at different current densities, it shows excellent rate capability with high reversible capacity.
Co-reporter:Zheng Chang, Xujiong Wang, Yaqiong Yang, Jie Gao, Minxia Li, Lili Liu and Yuping Wu
Journal of Materials Chemistry A 2014 - vol. 2(Issue 45) pp:NaN19450-19450
Publication Date(Web):2014/10/01
DOI:10.1039/C4TA04419C
A rechargeable lithium battery, Li//Br, is reported using an aqueous bromide/tribromide redox pair and a coated lithium metal as the positive and negative electrodes, respectively. The positive Br2 electrode shows fast redox kinetics and good stability. This battery presents excellent electrochemical performance with an average discharge voltage up to 3.96 V at 1.7 mA cm−2, an energy density of 1220 Wh kg−1, a power density of 29.7 mW cm−2 at a current density of 12.8 mA cm−2, and a long cycling life. There is no evidence of voltage decrease after 100 cycles at 35% DOD. It would become a good platform between lithium ion batteries and Li//air batteries since the former shows lower energy density and the latter has some challenging problems that need to be solved prior to practical application. This finding presents another promising choice for electrochemical energy storage systems.
Co-reporter:Qingsheng Gao, Lichun Yang, Xinchun Lu, Jianjiang Mao, Yahong Zhang, Yuping Wu and Yi Tang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 14) pp:NaN2812-2812
Publication Date(Web):2010/02/12
DOI:10.1039/B921001F
This paper presents a novel strategy to synthesize MoO2/carbon nanowires based on organic–inorganic hybrid nanocomposites with nanometre periodic structures. The organic–inorganic hybrid precursors provide uniform reactions throughout the composites for achieving novel carbon-hybrid structures and nano-morphology via easy calcination. Through the systematic physical characterization including scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, etc., the one-dimensional and carbon-hybrid structure of MoO2/C nanowires was confirmed. This synthetic strategy is also proved universal for other novel MoO2/C nanostructures based on various organic-inorganic hybrid precursors. Furthermore, the MoO2/C hybrid nanowires show good rate capability even at the high current density of 1000 mA g−1 as anode material for lithium ion battery.
Co-reporter:Wei Tang, Xiangwen Gao, Yusong Zhu, Yunbo Yue, Yi Shi, Yuping Wu and Kai Zhu
Journal of Materials Chemistry A 2012 - vol. 22(Issue 38) pp:NaN20145-20145
Publication Date(Web):2012/08/08
DOI:10.1039/C2JM34563C
A hybrid of V2O5 nanowires and MWCNTs coated with polypyrrole (PPy) was prepared as an anode material for ARLBs. The hybrid shows a good electrochemical reversibility since the PPy coating can effectively prevent the dissolution of the reduced vanadium ions.
Co-reporter:Yi Shi, Shu-Lei Chou, Jia-Zhao Wang, David Wexler, Hui-Jun Li, Hua-Kun Liu and Yuping Wu
Journal of Materials Chemistry A 2012 - vol. 22(Issue 32) pp:NaN16470-16470
Publication Date(Web):2012/06/20
DOI:10.1039/C2JM32649C
To reduce the reaction time, electrical energy consumption, and cost, LiFePO4/C/graphene has been synthesized by a rapid, one-pot, microwave-assisted hydrothermal method within 15 min at a temperature of 200 °C, followed by sintering at 600 °C for 2 h under a H2/Ar (5:95, v/v) atmosphere. The microstructure and morphology of the LiFePO4/C/graphene products were characterized by means of X-ray diffraction, Raman spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. The carbon coated LiFePO4/C nanoparticles, around 200 nm in size, are thoroughly wrapped by crumpled micrometer-size graphene sheets. In this kind of structure, the bridging graphene nanosheets can form an effective conducting network and provide interconnected open pores that favor electrolyte absorption and reduce the diffusion path of the lithium ions. The cyclic voltammograms, charge/discharge profiles, and AC impedance measurements indicated that the kinetics of the LiFePO4/C/graphene was better than that of LiFePO4/C. The LiFePO4/C/graphene composite exhibited a discharge capacity of 165 mA h g−1 at 0.1 C and 88 mA h g−1 at 10 C, respectively. Therefore, the LiFePO4/C/graphene composite is a promising candidate for the development of high-performance, cost-effective lithium batteries for the hybrid vehicle and electric vehicle markets.
Co-reporter:Lichun Yang, Lili Liu, Yusong Zhu, Xujiong Wang and Yuping Wu
Journal of Materials Chemistry A 2012 - vol. 22(Issue 26) pp:NaN13152-13152
Publication Date(Web):2012/04/30
DOI:10.1039/C2JM31364B
Carbon coated MoO2 nanobelts were successfully synthesized via a hydrothermal method followed by calcination under inert atmosphere, using α-MoO3 nanobelts as the precursor and self-template, ethanol as the reducer and glucose as the carbon source. Under the protection of polysaccharide resulting from glucose polycondensation, the 1-D morphology can be well retained during the reduction and carbonization processes. Tested as anode materials for lithium ion batteries, the carbon coated MoO2 nanobelts exhibit a reversible capacity of 769.3 mA h g−1 at a current density of 100 mA g−1 in the first cycle, and retain 80.2% of the capacity after 30 cycles. When the current density increases, this material shows high rate capability and good cycling performance.
Co-reporter:Yuyang Hou, Xujiong Wang, Yusong Zhu, Chenglin Hu, Zheng Chang, Yuping Wu and Rudolf Holze
Journal of Materials Chemistry A 2013 - vol. 1(Issue 46) pp:NaN14718-14718
Publication Date(Web):2013/09/27
DOI:10.1039/C3TA13472E
Our former research found that lithium metal coated with a gel polymer electrolyte and LISICON film can be stable in aqueous electrolytes to carry out lithium plating and dissolution, and is a good anode for high energy density aqueous rechargeable lithium batteries (ARLBs). Here we prepared three-dimensionally macroporous LiFePO4 and used it as the cathode to build another ARLB in 0.5 mol l−1 Li2SO4 aqueous solution. Its stable output voltage is 3.32 V with excellent cycling performance and good rate capability. Its energy density is much higher than that of previously reported traditional ARLBs, and is also higher than those for traditional lithium ion batteries based on graphitic carbon/organic electrolyte/LiFePO4. Its safety and reliability are also very good. The results suggests that the chemistry of post lithium ion batteries is of great promise for practical applications in electric vehicles.
Co-reporter:Yu Liu, Baihe Zhang, Yaqiong Yang, Zheng Chang, Zubiao Wen and Yuping Wu
Journal of Materials Chemistry A 2013 - vol. 1(Issue 43) pp:NaN13587-13587
Publication Date(Web):2013/09/09
DOI:10.1039/C3TA12902K
A nanocomposite of molybdenum trioxide (α-MoO3) nanobelts coated with polypyrrole has been fabricated by a simple in situ polymerization route. The structure, morphology and electrochemical performance of the nanocomposite were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and electrochemical measurements. It was found that the polypyrrole acted as a conducting matrix and a coating agent, which effectively improves the conductivity of the MoO3 nanobelts and inhibits the dissolution of molybdenum ions during cycling. The supercapacitor based on the PPy@MoO3 nanocomposite as the anode, activated carbon as the cathode and 0.5 M K2SO4 aqueous solution as the electrolyte exhibits better rate capability as well as excellent cycling performance compared to the virginal MoO3.
Co-reporter:Yusong Zhu, Shiying Xiao, Yi Shi, Yaqiong Yang and Yuping Wu
Journal of Materials Chemistry A 2013 - vol. 1(Issue 26) pp:NaN7797-7797
Publication Date(Web):2013/04/26
DOI:10.1039/C3TA00167A
A composite membrane based on poly(vinylidene fluoride) (PVDF) and lithium polyacrylic acid oxalate borate (LiPAAOB) exhibiting high safety (self-extinguishing) and good mechanical property was prepared. The ionic conductivity of the gel polymer electrolyte (GPE) by saturating with 1 mol L−1 LiPF6 electrolyte at ambient temperature can be up to 0.35 mS cm−1, higher than that of the well-used commercial separator (Celgard 2730), 0.21 mS cm−1. The lithium ion transference in the GPE at room temperature is 0.58, twice that in the commercial separator (0.27). Moreover, the GPE presents a true shut-down behavior, which is quite different from the not-real shut-down behaviour of the commercial separators. Furthermore, the absorbed electrolyte solvent is difficult to evaporate at elevated temperature. Its electrochemical performance is evaluated by using LiFePO4 cathode. The obtained results suggest that this composite GPE is very attractive to large-capacity battery systems requiring high safety and low cost.
Co-reporter:Lei Zhu, Zheng Chang, Yanfang Wang, Bingwei Chen, Yusong Zhu, Weiping Tang and Yuping Wu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 44) pp:NaN22072-22072
Publication Date(Web):2015/09/21
DOI:10.1039/C5TA05556C
Supercapacitors display high power density and long cycling life that are particularly amenable for use in the field of energy storage. However, the cost is a big issue for practical application. Here, cheap Fe2O3 spindles from a rich natural resource are used as the positive electrode. Through the twining of MnO2 nanoflakes via a simple and cost-effective hydrothermal method, a unique structure of a core–shell MnO2@Fe2O3 nanospindle has been prepared. The electrochemical performance of the nanospindles including capacitance and cycling life is markedly improved compared with the pristine Fe2O3 spindles. Its specific capacitance is up to 159 F g−1 at a current density of 0.1 A g−1 and especially, the capacitance retention is 97.4% after 5000 cycles in a 0.5 mol L−1 K2SO4 neutral aqueous electrolyte. Combined with activated carbon as the negative electrode, the energy density can be up to 43.8 W h kg−1 on the basis of the weights of the two electrodes. These results reveal that the core–shell MnO2@Fe2O3 nanospindles are a promising positive electrode for practical supercapacitors.
Co-reporter:Xiaowei Wang, Minxia Li, Yanfang Wang, Bingwei Chen, Yusong Zhu and Yuping Wu
Journal of Materials Chemistry A 2015 - vol. 3(Issue 16) pp:NaN8283-8283
Publication Date(Web):2015/03/19
DOI:10.1039/C5TA01947H
A Zn–NiO rechargeable battery comprising a NiO nanosheet anchored to CNTs as the positive electrode, a zinc plate as the negative one and an alkaline solution of 1 M KOH and 10 mM Zn(Ac)2 as the electrolyte is reported. It delivers a voltage of ∼1.75 V and a high energy density of 228 W h kg−1 (based on the mass of the positive electrode composite and zinc) with good cycling. It has great promise for practical energy storage applications.
Co-reporter:Faxing Wang, Zaichun Liu, Xiaowei Wang, Xinhai Yuan, Xiongwei Wu, Yusong Zhu, Lijun Fu and Yuping Wu
Journal of Materials Chemistry A 2016 - vol. 4(Issue 14) pp:NaN5123-5123
Publication Date(Web):2016/03/01
DOI:10.1039/C6TA01398H
Electrochemical capacitors are becoming promising energy conversion/storage and power output devices. However, high cost and low energy density are two serious disadvantages. By integrating the advantages of Li-/Na-ion batteries and electrochemical capacitors, Li-/Na-ion capacitors have been explored recently. Al is very cheap and is the most abundant metal element on the earth. There are few reports on Al-ion capacitors due to the challenges in finding a suitable anode with large capacitance and good rate performance. Here, the feasibility of assembling an Al-ion capacitor with good electrochemical performance is demonstrated. The Al-ion capacitor is assembled by using a composite of MoO3 nanotubes coated by a conductive polypyrrole (PPy@MoO3) as an anode, which functions via a redox intercalation/deintercalation of Al3+ ions in aqueous solution. It delivers a capacitance of 693 F g−1, about 3 times higher than that of electrode materials for sodium-ion capacitors in aqueous solution. Combined with an activated carbon (AC) cathode, the Al-ion capacitor presents an energy density of 30 W h kg−1 and an excellent cycling life with 93% capacitance retention after 1800 cycles. This finding provides another energy storage device with low cost and promotes the application of capacitors.
Co-reporter:Wei Tang, Lili Liu, Shu Tian, Lei Li, Yunbo Yue, Yuping Wu and Kai Zhu
Chemical Communications 2011 - vol. 47(Issue 36) pp:NaN10060-10060
Publication Date(Web):2011/08/09
DOI:10.1039/C1CC13474D
MoO3 nanoplates were prepared as anode material for aqueous supercapacitors. They can deliver a high energy density of 45 W h kg−1 at 450 W kg−1 and even maintain 29 W h kg−1 at 2 kW kg−1 in 0.5 M Li2SO4 aqueous electrolyte. These results present a new direction to explore non-carbon anode materials.
Co-reporter:Lili Liu, Yuyang Hou, Xiongwei Wu, Shiying Xiao, Zheng Chang, Yaqiong Yang and Yuping Wu
Chemical Communications 2013 - vol. 49(Issue 98) pp:NaN11517-11517
Publication Date(Web):2013/10/09
DOI:10.1039/C3CC46943C
Nanoporous selenium was prepared by a simple mechanical method adopting nano-CaCO3 as a template. When used as a cathode, it can exhibit relatively high capacity and good cycling behaviour. These results present great promise for this new cathode material for rechargeable lithium batteries of high energy density.
Co-reporter:Faxing Wang, Shiying Xiao, Zheng Chang, Yaqiong Yang and Yuping Wu
Chemical Communications 2013 - vol. 49(Issue 80) pp:NaN9211-9211
Publication Date(Web):2013/07/10
DOI:10.1039/C3CC44360D
Nanoporous LiNi1/3Co1/3Mn1/3O2 (NP-NCM) was synthesized by using vapour grown carbon fibers (VGCFs) as templates. It exhibits excellent electrochemical performance as a cathode material for aqueous rechargeable lithium batteries, especially with ultra-fast charge capability, and 72 mA h g−1 can be achieved at a charge time of 20 s.
Co-reporter:Yu Liu, Zubiao Wen, Xiongwei Wu, Xiaowei Wang, Yuping Wu and Rudolf Holze
Chemical Communications 2014 - vol. 50(Issue 89) pp:NaN13717-13717
Publication Date(Web):2014/09/05
DOI:10.1039/C4CC06622G
An acid-free lead rechargeable battery system comprising PbSO4 as the negative electrode, LiMn2O4 as the positive electrode and a neutral Li2SO4 aqueous solution as electrolyte is reported and its electrochemical performance is very good. It shows great promise to reduce the global use of lead by 50% since it is also low cost.
Co-reporter:Yu Liu, Zubiao Wen, Xiongwei Wu, Xiaowei Wang, Yuping Wu and Rudolf Holze
Chemical Communications 2016 - vol. 52(Issue 48) pp:NaN7620-7620
Publication Date(Web):2016/05/31
DOI:10.1039/C6CC90241C
Correction for ‘An acid-free rechargeable battery based on PbSO4 and spinel LiMn2O4’ by Yu Liu et al., Chem. Commun., 2014, 50, 13714–13717.
Co-reporter:Faxing Wang, Zaichun Liu, Xinhai Yuan, Jun Mo, Chunyang Li, Lijun Fu, Yusong Zhu, Xiongwei Wu and Yuping Wu
Journal of Materials Chemistry A 2017 - vol. 5(Issue 28) pp:NaN14929-14929
Publication Date(Web):2017/06/22
DOI:10.1039/C7TA03920D
Electrochemical capacitors are playing increasing roles in our daily life but their low energy densities limit their wide applications. The appearance of Li-ion capacitors (LICs) is regarded as the beginning of a new era of increased energy densities in the field of electrochemical capacitors. However, it is a great challenge to find a suitable anode material with superior electrochemical performance. In addition, the intrinsic instability of the liquid electrolytes used in LICs can easily result in leakage of the electrolyte and causes a serious safety issue. Here, a quasi-solid-state LIC is fabricated by applying Li3VO4/carbon nanofibers as the anode and electrochemically-exfoliated graphene sheets as the cathode in a gel polymer electrolyte. It achieves an energy density of 110 W h kg−1 and a good cycling performance. Our results demonstrate that quasi-solid-state LICs provide a key system acting as a bridge between conventional Li-ion batteries and supercapacitors, while meeting the high safety demands of electronic devices.
Co-reporter:Lili Liu, Haipeng Guo, Yuyang Hou, Jun Wang, Lijun Fu, Jun Chen, Huakun Liu, Jiazhao Wang and Yuping Wu
Journal of Materials Chemistry A 2017 - vol. 5(Issue 28) pp:NaN14681-14681
Publication Date(Web):2017/06/16
DOI:10.1039/C7TA03553E
Herein, a three-dimensional (3D) hierarchical porous Co3O4 nanotube (Co3O4 HPNT) network was prepared using a polypyrrole nanofiber (PPyNF) as a sacrificial template. When employed as a cathode for lithium–oxygen batteries, the 3D Co3O4 HPNT network demonstrated superior bifunctional electrocatalytic activities towards both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), with a relatively low charge overpotential of 99 mV and a high discharge/charge capacity of 4164/4299 mA h g−1. High-resolution scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy measurements on Co3O4 HPNT-based cathode after discharge/recharge showed reversible formation and decomposition of Li2O2. This superior performance is ascribed to the 3D web-like porous tubular structure, which facilitates rapid oxygen flow, provides enough void volume for insoluble Li2O2 deposition, and increases the catalytic utilization of Co3O4. Moreover, the hierarchical porous structure with meso-/nanopores on the walls of the Co3O4 nanotubes facilitates O2 diffusion, electrolyte penetration, and mass transport of all the reactants.
