Co-reporter:Yong Li;Shuan Wang;Danni Lei;Baohua Li;Feiyu Kang
Journal of Materials Chemistry A 2017 vol. 5(Issue 24) pp:12236-12242
Publication Date(Web):2017/06/20
DOI:10.1039/C7TA02361H
Titanium dioxide (TiO2) mesocrystals consist of a large number of subunits possessing distinct characteristics of large surface area, high crystallinity and large density and are considered as promising potential materials for energy storage and conversion, sensing, and photocatalysis. Therefore, it is significant to develop a robust and universal method to synthesize and precisely tune the TiO2 mesocrystals at low temperatures. However, this is still a big challenge and has not been largely achieved. In this context, we develop a robust method of synthesizing TiO2 mesocrystals by a facile hydrolysis and evolution process induced by acetic acid (HAc) solution at 80 °C using TiN as a starting material. The size and crystallinity of the TiO2 mesocrystals can be easily tuned by adjusting the HAc content and reaction time. The HAc governs the transformation of TiO2 from the amorphous state to the anatase phase at a low temperature (80 °C). The average size of the TiO2 mesocrystals can be tuned from ∼100 nm to 20 nm by changing the HAc content. TiO2 mesocrystals with a spindle-like morphology were formed and the tiny anatase TiO2 grains were grown along the same orientation [001] plane, which exhibits excellent electrochemical performance for lithium-ion storage. The specific capacity at 1C is 180 mA h g−1 and the retention is 92.9% after 100 cycles. Thereby, this study presents a universal method of crafting anatase TiO2 mesocrystals at low temperatures.
Co-reporter:Yong Li;Shuan Wang;Linkai Tang;Yusuf Valentino Kaneti;Wei Lv;Zhiqun Lin;Baohua Li;Quan-Hong Yang;Feiyu Kang
Journal of Materials Chemistry A 2017 vol. 5(Issue 9) pp:4359-4367
Publication Date(Web):2017/02/28
DOI:10.1039/C6TA08611J
Titanium oxide (TiO2) has attracted great interest as a promising anode material for lithium (Li) ion batteries (LIBs) and sodium (Na) ion batteries (SIBs). However, the key factors that dictate the Li-ion and Na-ion storage and transportation in TiO2 remain unclear. Herein, we report a facile hydrolysis route to crafting a variety of high tap-density TiO2 spheres with controllable size and hierarchical pores. The Li-ion and Na-ion storage properties based on these TiO2 spheres were systematically investigated. The pore distribution and the size of TiO2 spheres were found to exert profound influence on the Li-ion and Na-ion storage and transportation. The Li-ion storage and transportation in dense TiO2 spheres was dependent mainly upon the micropore distribution and volume and independent of the size of spheres. In contrast, the excellent Na-ion storage and transportation in TiO2 spheres was enabled by the loose structure with a large macroscopic pore volume and shortened Na-ion diffusion length. High tap-density TiO2 spheres (1.06 g cm−3) with superior Li-ion and Na-ion storage properties were produced, exhibiting a Li-ion storage specific capacity of 189 mA h g−1 at 1C and a high capacity retention of 88.1% after 100 cycles, and a Na-ion storage specific capacity of 184 mA h g−1 at 1C and capacity retention of 90.5% after 200 cycles. The ability to understand the critical factors controlling the Li-ion and Na-ion storage in high tap-density TiO2 spheres enables their implementation for practical applications in Li-ion and Na-ion batteries.
Co-reporter:Yusuf Valentino Kaneti;Jun Zhang;Zhijie Wang;Shunsuke Tanaka;Md Shahriar A. Hossain;Zheng-Ze Pan;Bin Xiang;Quan-Hong Yang;Yusuke Yamauchi
Journal of Materials Chemistry A 2017 vol. 5(Issue 29) pp:15356-15366
Publication Date(Web):2017/07/25
DOI:10.1039/C7TA03939E
Metal–organic frameworks (MOFs) have gained significant attention as precursors for the fabrication of porous hybrid materials due to their highly controllable composition, structure and pore size. However, at present, MOF-derived materials have rarely been investigated as anode materials for sodium-ion batteries. In this work, we report the fabrication of a Ni-doped Co/CoO/N-doped carbon (NC) hybrid using bimetallic Ni–Co-ZIF as the starting precursor. The resulting Ni-doped Co/CoO/NC hybrid is highly microporous with a high specific surface area of 552 m2 g−1. When employed as an anode material for sodium-ion batteries, the Ni-doped Co/CoO/NC hybrid exhibited both good rate performance with a high discharge capacity of 218 mA h g−1 at a high current density of 500 mA g−1 and good cycling stability, as a high discharge capacity of 218.7 mA h g−1 can be retained after 100 cycles at 500 mA g−1, corresponding to a high capacity retention of 87.5%. The excellent electrochemical performance of the Ni-doped Co/CoO/NC hybrid for SIBs may be attributed to the synergistic effects of various factors, including: (i) the presence of a carbon matrix which provides protection against aggregation and pulverization during sodiation/desodiation; (ii) the highly microporous nature along with the presence of a few mesopores which facilitates better insertion/de-insertion of Na+ ions; (iii) the Ni-doping which introduces defect sites into the atomic structure of CoO via partial substitution, thus enhancing the conductivity of the cobalt oxide (CoO) component and hence, the overall hybrid material, and (iv) the N-doping which promotes a faster migration speed of sodium ions (Na+) across the carbon layer by creating defect sites, thereby improving the conductivity of the carbon frameworks in the hybrid material.
Co-reporter:Xilin Li;Kun Qian;Cheng Liu;Decheng An;Yiyang Li;Dong Zhou;Zhiqun Lin;Baohua Li;Quan-Hong Yang;Feiyu Kang
Journal of Materials Chemistry A 2017 vol. 5(Issue 35) pp:18888-18895
Publication Date(Web):2017/09/12
DOI:10.1039/C7TA04415A
The ability to judiciously utilize gel-polymer electrolytes (GPEs) that replace liquid electrolytes is widely recognized as an attractive route to solving the safety concerns of Li-ion batteries (LIBs). In this context, novel LiNi0.8Co0.15Al0.05O2 (NCA)/graphite GPE and NCA/graphite–Si/C GPE batteries with high energy density and excellent electrochemical and safety performances are developed via in situ polymerization of pentaerythritol tetraacrylate (PETEA) in a liquid electrolyte. Notably, the capacity retention of NCA/graphite and NCA/graphite-Si/C GPE batteries after 200 cycles at the discharge rate of 5C is 92.5% and 81.2%, respectively, which are much larger than those implementing liquid electrolytes (i.e., only 55.9% and 51.4%, respectively). Interestingly, the GPE batteries also displayed considerably lower gas production, especially the graphite-Si/C anode battery, and did not undergo a violent combustion during the nail penetration test compared to the liquid electrolyte batteries. The markedly enhanced performances noted above can be attributed to the three-dimensional framework of the GPE which promoted the formation of a very tight protective film on the surface of the electrodes during cycling, thereby inhibiting the cyclable Li consumption and side reactions with the electrolyte. Furthermore, such a protective film effectively retained the structural integrity of the electrodes during the cycling process and reduced the heat reactions between the electrodes and electrolyte.
Co-reporter:Linkai Tang;Chao Wang;Shuan Wang;Marnix Wagemaker;Baohua Li;Quan-Hong Yang;Feiyu Kang
Advanced Science 2017 Volume 4(Issue 5) pp:
Publication Date(Web):2017/05/01
DOI:10.1002/advs.201600311
Nanosized Li4Ti5O12 (LTO) materials enabling high rate performance suffer from a large specific surface area and low tap density lowering the cycle life and practical energy density. Microsized LTO materials have high density which generally compromises their rate capability. Aiming at combining the favorable nano and micro size properties, a facile method to synthesize LTO microbars with micropores created by ammonium bicarbonate (NH4HCO3) as a template is presented. The compact LTO microbars are in situ grown by spinel LTO nanocrystals. The as-prepared LTO microbars have a very small specific surface area (6.11 m2 g−1) combined with a high ionic conductivity (5.53 × 10−12 cm−2 s−1) and large tap densities (1.20 g cm−3), responsible for their exceptionally stable long-term cyclic performance and superior rate properties. The specific capacity reaches 141.0 and 129.3 mAh g−1 at the current rate of 10 and 30 C, respectively. The capacity retention is as high as 94.0% and 83.3% after 500 and 1000 cycles at 10 C. This work demonstrates that, in situ creating micropores in microsized LTO using NH4HCO3 not only facilitates a high LTO tap density, to enhance the volumetric energy density, but also provides abundant Li-ion transportation channels enabling high rate performance.
Co-reporter:Juanjuan Yin, Zhaojun Ding, Danni Lei, Linkai Tang, Jiaojiao Deng, Baohua Li, Yan-Bing He
Journal of Alloys and Compounds 2017 Volume 712(Volume 712) pp:
Publication Date(Web):25 July 2017
DOI:10.1016/j.jallcom.2017.04.055
•Zn0.12Co0.88CO3 is synthesized via one-step solvothermal method.•Zn0.12Co0.88CO3 composite presents high tap density (2.11 g cm−3).•The Zn0.12Co0.88CO3/CNT exhibits high capacity and excellent rate capability.•The CNT networks provide conductive network and buffer for Zn0.12Co0.88CO3 particles.Multicomponent composites with an atomic-scale distribution of different component and an integrated lattice structure may manifest an enhanced synergistic effect compared to the mechanical mixture. In this paper, multicomponent Zn0.12Co0.88CO3 composite with high tap density (2.11 g cm−3) synthesized via one-step solvothermal method, which exhibits hexagonal structure similar to that of the monocomponent cobalt carbonate (CoCO3). The Zn-substitution could significantly improve the charge and discharge capacity of CoCO3 from 1001.6 mAh g−1 to 1253.7 mAh g−1 at 0.2 C. When the Zn-substituted CoCO3 is embedded in carbon nanotubes (CNT) network, the rate performance of Zn0.12Co0.88CO3 can be improved greatly. The resulting Zn0.12Co0.88CO3/CNT exhibits outstanding rate performance, delivering a reversible capacity of 1098.4, 840.8, and 610.7 mAh g−1 at 0.5, 1 and 2 C, respectively. The excellent performance of Zn0.12Co0.88CO3/CNT is ascribed to the unique micro-sphere structure with carbon nanotubes. The elastic CNT networks are introduced to wrap the Zn0.12Co0.88CO3, which can not only provide a highly conductive network for electron transfer, but also serve as a buffer to alleviate the aggregation and volume changes of Zn0.12Co0.88CO3 nanoparticles. The Zn0.12Co0.88CO3/CNT composite may serve as a novel high-capacity LIBs anode material for practical application, and a facile strategic approach is introduced for the full-molar-ratio synthesis of multicomponent composites.
Co-reporter:Qinbai Yun;Wei Lv;Yan Zhao;Baohua Li;Feiyu Kang;Quan-Hong Yang
Advanced Materials 2016 Volume 28( Issue 32) pp:6932-6939
Publication Date(Web):
DOI:10.1002/adma.201601409
Co-reporter:Dong Zhou;Ruliang Liu;Fengyun Li;Ming Liu;Baohua Li;Quan-Hong Yang;Qiang Cai;Feiyu Kang
Advanced Energy Materials 2016 Volume 6( Issue 7) pp:
Publication Date(Web):
DOI:10.1002/aenm.201502214
The low Coulombic efficiency and serious security issues of lithium (Li) metal anode caused by uncontrollable Li dendrite growth have permanently prevented its practical application. A novel SiO2 hollow nanosphere-based composite solid electrolyte (SiSE) for Li metal batteries is reported. This hierarchical electrolyte is fabricated via in situ polymerizing the tripropylene gycol diacrylate (TPGDA) monomer in the presence of liquid electrolyte, which is absorbed in a SiO2 hollow nanosphere layer. The polymerized TPGDA framework keeps the prepared SiSE in a quasi-solid state without safety risks caused by electrolyte leakage, meanwhile the SiO2 layer not only acts as a mechanics-strong separator but also provides the SiSE with high room-temperature ionic conductivity (1.74 × 10−3 S cm−1) due to the high pore volume (1.49 cm3 g−1) and large liquid electrolyte uptake of SiO2 hollow nanospheres. When the SiSE is in situ fabricated on the cathode and applied to LiFePO4/SiSE/Li batteries, the obtained cells show a significant improvement in cycling stability, mainly attributed to the stable electrode/electrolyte interface and remarkable suppression for Li dendrite growth by the SiSE. This work can extend the application of hollow nanooxide and enable a safe, efficient operation of Li anode in next generation energy storage systems.
Co-reporter:Xin-Zhen Zhang, Da Han, Yan-Bing He, Deng-Yun Zhai, Dongqing Liu, Hongda Du, Baohua Li and Feiyu Kang
Journal of Materials Chemistry A 2016 vol. 4(Issue 20) pp:7727-7735
Publication Date(Web):13 Apr 2016
DOI:10.1039/C6TA00331A
Hexagonal close packed Cr2O3, fabricated by an electrospinning technique combined with a heating method, is adopted for the first time as a catalyst for non-aqueous lithium–oxygen (Li–O2) batteries. The synthesized highly mesoporous Cr2O3 nanotubes (Cr2O3-MNT) with a large surface area of 53.4 m2 g−1 are confirmed by field emission scanning electron microscopy (FESEM), field emission high-resolution transmission electron microscopy (TEM) and nitrogen adsorption/desorption isotherms (BET). By using the prepared Super P (SP) (60 wt%)/Cr2O3 (30 wt%)/polyvinylidenefluoride (PVDF) (10 wt%) composite as an oxygen electrode, the Li–O2 battery shows an astonishingly enhanced capacity of 8280 mA h g−1 at a current density of 50 mA g−1. More encouragingly, when the current densities are fixed at 25, 50, 100 and 200 mA g−1 with a limited capacity of 500 mA h g−1, the charging potentials are 3.47, 3.51, 3.78 and 4.01 V, respectively, which are among the lowest charge potentials reported to date. By using a capacity-controlled method (1000 mA h g−1) at a current density of 100 mA g−1, the cell shows excellent cyclic stability up to 50 cycles. The reversible formation and dissociation of Li2O2 are verified by X-ray diffusion (XRD) and SEM, indicating that the as-prepared Cr2O3 nanotubes are a promising catalyst for Li–O2 batteries.
Co-reporter:Rui Tang, Qinbai Yun, Wei Lv, Yan-Bing He, Conghui You, Fangyuan Su, Lei Ke, Baohua Li, Feiyu Kang, Quan-Hong Yang
Carbon 2016 Volume 103() pp:356-362
Publication Date(Web):July 2016
DOI:10.1016/j.carbon.2016.03.032
This work demonstrates how a very low fraction of graphene greatly enhances the usage efficiency of carbon-based conductive additive in LiCoO2-based lithium ion batteries (LIB) and develops a strategy using binary conductive additive to have a high performance battery, especially with excellent rate performance. With a much lower fraction of carbon additive for a commercial LIB, only 0.2 wt% graphene nanosheet (GN) together with 1 wt% Super-P (SP) constructing an effective conductive network, the prepared battery exhibits outstanding cycling stability (146 mAhg−1 at 1C with retention of 96.4% after 50 cycles) and rate capability (116.5 mAhg−1 even at 5C). In this battery, a composite conducting network is formed with a long-range electron pathway formed by a trace amount of GN and the short-range electron pathway by aggregation of SP particles. More interestingly, in micro-sized LiCoO2 system, the GN additive does not present hindrance effect for lithium ion transport even in high rate discharge, which is entirely different from the nano-sized LiFePO4 system. This study further demonstrates commercial potential of GN additive for high performance LIB and more importantly gives a well-designed recipe for its real application.
Co-reporter:Chao Wang, Shuan Wang, Linkai Tang, Yan-Bing He, Lin Gan, Jia Li, Hongda Du, Baohua Li, Zhiqun Lin, Feiyu Kang
Nano Energy 2016 Volume 21() pp:133-144
Publication Date(Web):March 2016
DOI:10.1016/j.nanoen.2016.01.005
•Monodisperse Li4Ti5O12(LTO) nanospheres are crafted using TiN by the pH regulation.•Alkali environment effectively controls the formation of TiO2/Li+ nanospheres.•LTO can maintain the nanospheres by polyvinyl pyrrolidone coating layer.•The LTO nanospheres show high taping density and excellent performance.The ability to synthesizing monodisperse Li4Ti5O12 (LTO) nanospheres is the key to reducing the irreversible capacity of LTO materials, and thus improving their power performance. However, it remains a grand challenge to achieve uniform precursors of LTO nanospheres and maintain their spherical structures after annealing. Herein, we develop a robust strategy for the synthesis of monodisperse LTO nanospheres with an average diameter of 120 nm via the use of titanium nitride (TiN) as a titanium source for lithium ion batteries (LIBs). The precursors composed of uniform TiO2/Li+ nanospheres were formed in a stable alkaline environment during the course of heating of the solution of peroxo-titanium complex as a result of the dissolution of TiN, while TiO2/Li+ microspheres were easily yielded with the decrease in pH value of the precursor solution. The OH− anion was found to effectively retard the hydrolysis of peroxo-titanium complex as well as the aggregation of TiO2/Li+ nanoparticles. Intriguingly, a uniform polyvinyl pyrrolidone (PVP) layer formed in-situ on the surface of TiO2/Li+ nanospheres rendered LTO to retain the monodisperse spherical morphology after annealing. Notably, the as-prepared monodisperse LTO nanospheres comprised of the interconnected LTO nanograins with an average size of ~15 nm uniformly coated by a carbon layer derived from the carbonization of PVP exhibited a high tap density (1.1 g cm−3) and an outstanding rate-cycling capability. The charge specific capacities at 1, 10, 50 and 80 C were 159.5, 151.1, 128.8 and 108.9 mAh g−1, respectively. More importantly, the capacity retention after 500 cycles at 10 C was as high as 92.6%. This work opens up an avenue to craft the uniform precursors of LTO and thus monodisperse LTO nanospheres that possess superior rate performance with high volumetric energy densities and long-term cyclic stability.
Co-reporter:Ming Liu, Dong Zhou, Yan-Bing He, Yongzhu Fu, Xianying Qin, Cui Miao, Hongda Du, Baohua Li, Quan-Hong Yang, Zhiqun Lin, T.S. Zhao, Feiyu Kang
Nano Energy 2016 Volume 22() pp:278-289
Publication Date(Web):April 2016
DOI:10.1016/j.nanoen.2016.02.008
•A PETEA-based GPE with an extremely high ionic conductivity was in-situ synthesized.•The polymer Li–S battery carried significantly enhanced electrochemical performances.•The immobilization of polysulfides was experimentally testified.•A high-performance flexible polymer Li–S battery was successfully crafted.The ability to suppress the dissolution of lithium polysulfides in liquid electrolyte (LE) is emerging and scientifically challenging, representing an important endeavor toward successful commercialization of lithium–sulfur (Li–S) batteries. In this context, a common and effective strategy to address this challenge is to replace the LE with a gel polymer electrolyte (GPE). However, the limited ionic conductivity of state-of-the-art GPEs and poor electrode/GPE interfaces greatly restrict their implementation. Herein, we report, for the first time, a facile in-situ synthesis of pentaerythritol tetraacrylate (PETEA)-based GPE with an extremely high ionic conductivity (1.13×10−2 S cm−1). Quite intriguingly, even interfaced with a bare sulfur cathode, this GPE rendered the resulting polymer Li–S battery with a low electrode/GPE interfacial resistance, high rate capacity (601.2 mA h g−1 at 1 C) and improved capacity retention (81.9% after 400 cycles at 0.5 C). These remarkable performances can be ascribed to the immobilization of soluble polysulfides imparted by PETEA-based GPE and the construction of a robust integrated GPE/electrode interface. Notably, due to the tight adhesion between the PETEA-based GPE and electrodes, a high-performance flexible polymer Li–S battery was successfully crafted. This work therefore opens up a convenient, low-cost and effective way to substantially enhance the capability of Li–S batteries, a key step toward capitalizing on GPE for high-performance Li–S batteries.
Co-reporter:Zhijie Wang, Xiaoliang Yu, Wenhui He, Yusuf Valentino Kaneti, Da Han, Qi Sun, Yan-Bing He, and Bin Xiang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 49) pp:
Publication Date(Web):November 23, 2016
DOI:10.1021/acsami.6b12570
Two-dimensional nanocarbons are intriguing functional materials for energy storage. However, the serious aggregation problems hinder their wider applications. To address this issue, we developed a unique two-dimensional hierarchical carbon architecture (2D-HCA) with ultrasmall graphene-like carbon nanosheets uniformly grown on hexagonal carbon nanoplates. The obtained 2D-HCA shows an interconnected porous structure and abundant heteroelement doping. When employed as anode for lithium ion batteries, it exhibits a high discharge capacity of 748 m Ah g–1 even after 400 cycles at 2 A g–1.Keywords: 2D hierarchical architecture; 2D subunits; lithium ion batteries; nanocarbon materials; porous structure;
Co-reporter:Dong Zhou;Ruliang Liu;Ming Liu;Hongda Du;Baohua Li;Qiang Cai;Quan-Hong Yang;Feiyu Kang
Advanced Energy Materials 2015 Volume 5( Issue 15) pp:
Publication Date(Web):
DOI:10.1002/aenm.201500353
A hierarchical all-solid-state electrolyte based on nitrile materials (SEN) is prepared via in situ synthesis method. This hierarchical structure is fabricated by in situ polymerizing the cyanoethyl polyvinyl alcohol (PVA-CN) in succinonitrile (SN)-based solid electrolyte that is filled in the network of polyacrylonitrile (PAN)-based electrospun fiber membrane. The crosslinked PVA-CN polymer framework is uniformly dispersed in the SN-based solid electrolyte, which can strongly enhance its mechanical strength and keeps it in a quasi-solid state even over the melting point. The electrospun fiber membrane efficiently reduces the thickness of SEN film besides a further improvement in strength. Because of the unique hierarchical structure and structure similarity among the raw materials, the prepared SEN film exhibits high room-temperature ionic conductance (0.30 S), high lithium ion transference number (0.57), favorable mechanical strength (15.31 MPa), excellent safety, and good flexibility. Furthermore, the in situ synthesis ensures an excellent adhesion between SEN and electrodes, which leads to an outstanding electrochemical performance for the assembled LiFePO4/SEN/Li cells. Both the superior performance of SEN and the simple fabricating process of SEN-based all-solid-state cells make it potentially as one of the most promising electrolyte materials for next generation lithium-ion batteries.
Co-reporter:Chao Wang, Shuan Wang, Yan-Bing He, Linkai Tang, Cuiping Han, Cheng Yang, Marnix Wagemaker, Baohua Li, Quan-Hong Yang, Jang-Kyo Kim, and Feiyu Kang
Chemistry of Materials 2015 Volume 27(Issue 16) pp:5647
Publication Date(Web):July 8, 2015
DOI:10.1021/acs.chemmater.5b02027
One of the key challenges toward high-power Li-ion batteries is to develop cheap, easy-to-prepare materials that combine high volumetric and gravimetric energy density with high power densities and a long cycle life. This requires electrode materials with large tap densities, which generally compromises the charge transport and hence the power density. Here densely packed Li4Ti5O12 (LTO) submicrospheres are prepared via a simple and easily up-scalable self-assembly process, resulting in very high tap densities (1.2 g·cm–3) and displaying exceptionally stable long-term high rate cyclic performance. The specific capacities at a (dis)charge rate of 10 and 20 C reach 148.6 and 130.1 mAh g–1, respectively. Moreover, the capacity retention ratio is 97.3% after 500 cycles at 10 C in a half cell, and no obvious capacity reduction is found even after 8000 cycles at 30 C in a full LiFePO4/LTO battery. The excellent performance is explained by the abundant presence of grain boundaries between the nanocrystallites in the submicron spheres creating a 3D interconnected network, which allows very fast Li-ion and electron transport as indicated by the unusually large Li-ion diffusion coefficients and electronic conductivity at (6.2 × 10−12 cm2 s−1 at 52% SOC and 3.8 × 10−6 S cm−1, respectively). This work demonstrates that, unlike in porous and nanosheet LTO structures with a high carbon content, exceptionally high rate charge transport can be combined with a large tap density and hence a large volumetric energy density, with the additional advantage of a much longer cycle life. More generally, the present results provide a promising strategy toward electrode materials combining high rate performances with high volumetric energy densities and long-term cyclic stability as required for the application in electric vehicles and tools.
Co-reporter:Xianying Qin, Haoran Zhang, Junxiong Wu, Xiaodong Chu, Yan-Bing He, Cuiping Han, Cui Miao, Shuan Wang, Baohua Li, Feiyu Kang
Carbon 2015 Volume 87() pp:347-356
Publication Date(Web):June 2015
DOI:10.1016/j.carbon.2015.02.044
Fe3O4 nanoparticles encapsulated in porous carbon fibers (Fe3O4@PCFs) as anode materials in lithium ion batteries are fabricated by a facile single-nozzle electrospinning technique followed by heat treatment. A mixed solution of polyacrylonitrile (PAN) and polystyrene (PS) containing Fe3O4 nanoparticles is utilized to prepare hybrid precursor fibers of Fe3O4@PS/PAN. The resulted porous Fe3O4/carbon hybrid fibers composed of compact carbon shell and Fe3O4-embeded honeycomb-like carbon core are formed due to the thermal decomposition of PS and PAN. The Fe3O4@PCF composite demonstrates an initial reversible capacity of 1015 mAh g−1 with 84.4% capacity retention after 80 cycles at a current density of 0.2 A g−1. This electrode also exhibits superior rate capability with current density increasing from 0.1 to 2.0 A g−1, and capacity retention of 91% after 200 cycles at 2.0 A g−1. The exceptionally high performances are attributed to the high electric conductivity and structural stability of the porous carbon fibers with unique structure, which not only buffers the volume change of Fe3O4 with the internal space, but also acts as high-efficient transport pathways for ions and electrons. Furthermore, the compact carbon shell can promote the formation of stable solid electrolyte interphase on the fiber surface.
Co-reporter:Lei Ke, Wei Lv, Fang-Yuan Su, Yan-Bing He, Cong-Hui You, Baohua Li, Zhengjie Li, Quan-Hong Yang, Feiyu Kang
Carbon 2015 Volume 92() pp:311-317
Publication Date(Web):October 2015
DOI:10.1016/j.carbon.2015.04.064
Because of high electrical conductivity, graphene has been widely investigated as conductive additive in lithium-ion batteries. Whereas, it is found that graphene has quite different influences on the rate performance in diverse evaluation systems, such as commercial soft-packed cells and coin half-cells. It has been proved that the coin cells show better high-rate performance with the increase of graphene content, while it is of the opposite trend in commercial cells. In normal cases, the electrode thickness of coin cells is much smaller than that of commercial cells. Herein, it is found that the electrode thickness has a considerable effect on the high-rate performance of LiFePO4 electrode in which graphene is used as the conductive additive. Thicker electrode results in a longer Li-ion diffusion path, and thus the steric effect that graphene could hinder the Li-ion diffusion is amplified, inducing much higher polarization and poorer performance at high rate. Comparatively, this phenomenon is not obvious in thinner electrode. Thus, when more graphene is introduced in thick electrode, the power performance is greatly weakened as is observed in the commercial cells. This finding is of great importance for designing a high-performance commercial lithium-ion battery with graphene additives.
Co-reporter:Qinbai Yun, Xianying Qin, Wei Lv, Yan-Bing He, Baohua Li, Feiyu Kang, Quan-Hong Yang
Carbon 2015 Volume 93() pp:59-67
Publication Date(Web):November 2015
DOI:10.1016/j.carbon.2015.05.032
Graphene and other carbon materials have been combined with various silicon (Si) nanostructures to accommodate the volume change of Si and enhance their electrical conductivity. However, for most of the formed hybrids, their low initial Coulombic efficiency (CE), fragile structures and poor stability cannot meet the practical application of battery. In this work, inspired by the structure and composition of reinforced concrete, a Si nanoparticles embedded in porous carbon/graphene (Si-C/G) electrode is fabricated through directly calcining a Si-polyacrylonitrile/graphene oxide precursor on a current collector. In this concrete-like structure, amorphous carbon, the carbonization product of polyacrylonitrile, acts as the “cement” and binds all components together. The flexible graphene network effectively enhances the strength, flexibility and conductivity of the electrode, as does the reinforcing rod framework in concrete. This carbon/graphene scaffold can accommodate the volume expansion of Si and isolate Si from electrolyte. Such Si-C/G electrode with small surface area and compact structure achieves a high initial CE of 78% and a reversible capacity of 1711 mAh g−1, as well as outstanding rate and cycling performances.
Co-reporter:Yu-Ying Huang, Da Han, Yan-Bing He, Qinbai Yun, Ming Liu, Xianying Qin, Baohua Li, Feiyu Kang
Electrochimica Acta 2015 Volume 184() pp:364-370
Publication Date(Web):1 December 2015
DOI:10.1016/j.electacta.2015.10.087
•A novel Si/slightly exfoliated graphite(SEG)/carbon composite anode is fabricated.•The Si nanoparticles are uniformly intercalated in the squashed interlayers of SEG.•The interlayers of SEG structure with embedded Si is filled by amorphous carbon.•The Si/SEG/C composite possesses high volumetric capacity of 1050 mAh cm−3.To boost the commercialization of high energy density lithium ion batteries (LIBs) used for electric vehicles, the development of electrode materials with high volumetric capacity is of great significance. In this work, a novel Si/slightly exfoliated graphite (SEG)/carbon composite used as anode for LIBs with high volumetric capacity is fabricated. The Si nanoparticles are uniformly intercalated in the squashed interlayers of SEG which are then further filled by amorphous carbon. The SEG acts as a conductivity skeleton, while the spaces between squashed interlayers(folds) in SEG function as buffer spaces for the expansion of Si nanoparticles during lithiation reactions. The amorphous carbon connects the Si nanoparticles with SEG to form a 3D conductive network. Owing to the high packing density (0.7 g cm−3) and unique structure, this material possesses a high volumetric capacity of 1050 mAh cm−3. Meanwhile, the Si/SEG/C composite also exhibits excellent rate and cyclic performance, presenting a reversible capacities of 1456 and 1056 mAh g−1 at 100 and 500 mA g−1 with capacity retention of 84.7% after 50 cycles at 500 mA g−1. This work opens up an avenue to craft the Si/C composite with high volumetric energy densities and rate performance.
Co-reporter:Cui Miao, Ming Liu, Yan-Bing He, Xianying Qin, Linkai Tang, Bing Huang, Rui Li, Baohua Li, Feiyu Kang
Energy Storage Materials (April 2016) Volume 3() pp:98-105
Publication Date(Web):1 April 2016
DOI:10.1016/j.ensm.2016.01.006
Tin peroxide (SnO2) is one of most potential anode materials for lithium ion batteries with high energy density because of its appropriate (de)lithiation potential and high specific capacity. However, the poor cycling property of SnO2 restricts its wide application in lithium ion battery. Herein, a novel monodispersed porous SnO2 nanospheres/graphene/porous carbon composite electrode with excellent performance is constructed. In this electrode, the SnO2 nanospheres with a diameter of ~60 nm are embedded in porous carbon, which is filled between the interlayers of graphene sheets. The carbon can protect the SnO2 nanospheres from contacting with the electrolyte. The pores inside both SnO2 nanospheres and carbon can accommodate the huge volume expansion of SnO2 nanoparticles during charge–discharge process. The graphene sheets can greatly improve the strength, stability and flexibility of the electrode. The framework formed by graphene and porous carbon can successfully prevent the aggregation of SnO2 nanospheres and collapse of SnO2 composite electrode. As a result, the composite electrode shows excellent rate performance, which achieves discharge capacities of 816.3, 704.6, 600 and 459.4 mAh g−1 at current densities of 0.2, 0.5, 1 and 2 A g−1 and delivers a capacity of 873.2 mAh g−1 after 200 cycles at 0.2 A g−1.
Co-reporter:Xin-Zhen Zhang, Da Han, Yan-Bing He, Deng-Yun Zhai, Dongqing Liu, Hongda Du, Baohua Li and Feiyu Kang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 20) pp:NaN7735-7735
Publication Date(Web):2016/04/13
DOI:10.1039/C6TA00331A
Hexagonal close packed Cr2O3, fabricated by an electrospinning technique combined with a heating method, is adopted for the first time as a catalyst for non-aqueous lithium–oxygen (Li–O2) batteries. The synthesized highly mesoporous Cr2O3 nanotubes (Cr2O3-MNT) with a large surface area of 53.4 m2 g−1 are confirmed by field emission scanning electron microscopy (FESEM), field emission high-resolution transmission electron microscopy (TEM) and nitrogen adsorption/desorption isotherms (BET). By using the prepared Super P (SP) (60 wt%)/Cr2O3 (30 wt%)/polyvinylidenefluoride (PVDF) (10 wt%) composite as an oxygen electrode, the Li–O2 battery shows an astonishingly enhanced capacity of 8280 mA h g−1 at a current density of 50 mA g−1. More encouragingly, when the current densities are fixed at 25, 50, 100 and 200 mA g−1 with a limited capacity of 500 mA h g−1, the charging potentials are 3.47, 3.51, 3.78 and 4.01 V, respectively, which are among the lowest charge potentials reported to date. By using a capacity-controlled method (1000 mA h g−1) at a current density of 100 mA g−1, the cell shows excellent cyclic stability up to 50 cycles. The reversible formation and dissociation of Li2O2 are verified by X-ray diffusion (XRD) and SEM, indicating that the as-prepared Cr2O3 nanotubes are a promising catalyst for Li–O2 batteries.
Co-reporter:Yong Li, Shuan Wang, Danni Lei, Yan-Bing He, Baohua Li and Feiyu Kang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 24) pp:NaN12242-12242
Publication Date(Web):2017/05/10
DOI:10.1039/C7TA02361H
Titanium dioxide (TiO2) mesocrystals consist of a large number of subunits possessing distinct characteristics of large surface area, high crystallinity and large density and are considered as promising potential materials for energy storage and conversion, sensing, and photocatalysis. Therefore, it is significant to develop a robust and universal method to synthesize and precisely tune the TiO2 mesocrystals at low temperatures. However, this is still a big challenge and has not been largely achieved. In this context, we develop a robust method of synthesizing TiO2 mesocrystals by a facile hydrolysis and evolution process induced by acetic acid (HAc) solution at 80 °C using TiN as a starting material. The size and crystallinity of the TiO2 mesocrystals can be easily tuned by adjusting the HAc content and reaction time. The HAc governs the transformation of TiO2 from the amorphous state to the anatase phase at a low temperature (80 °C). The average size of the TiO2 mesocrystals can be tuned from ∼100 nm to 20 nm by changing the HAc content. TiO2 mesocrystals with a spindle-like morphology were formed and the tiny anatase TiO2 grains were grown along the same orientation [001] plane, which exhibits excellent electrochemical performance for lithium-ion storage. The specific capacity at 1C is 180 mA h g−1 and the retention is 92.9% after 100 cycles. Thereby, this study presents a universal method of crafting anatase TiO2 mesocrystals at low temperatures.
Co-reporter:Yusuf Valentino Kaneti, Jun Zhang, Yan-Bing He, Zhijie Wang, Shunsuke Tanaka, Md Shahriar A. Hossain, Zheng-Ze Pan, Bin Xiang, Quan-Hong Yang and Yusuke Yamauchi
Journal of Materials Chemistry A 2017 - vol. 5(Issue 29) pp:NaN15366-15366
Publication Date(Web):2017/07/13
DOI:10.1039/C7TA03939E
Metal–organic frameworks (MOFs) have gained significant attention as precursors for the fabrication of porous hybrid materials due to their highly controllable composition, structure and pore size. However, at present, MOF-derived materials have rarely been investigated as anode materials for sodium-ion batteries. In this work, we report the fabrication of a Ni-doped Co/CoO/N-doped carbon (NC) hybrid using bimetallic Ni–Co-ZIF as the starting precursor. The resulting Ni-doped Co/CoO/NC hybrid is highly microporous with a high specific surface area of 552 m2 g−1. When employed as an anode material for sodium-ion batteries, the Ni-doped Co/CoO/NC hybrid exhibited both good rate performance with a high discharge capacity of 218 mA h g−1 at a high current density of 500 mA g−1 and good cycling stability, as a high discharge capacity of 218.7 mA h g−1 can be retained after 100 cycles at 500 mA g−1, corresponding to a high capacity retention of 87.5%. The excellent electrochemical performance of the Ni-doped Co/CoO/NC hybrid for SIBs may be attributed to the synergistic effects of various factors, including: (i) the presence of a carbon matrix which provides protection against aggregation and pulverization during sodiation/desodiation; (ii) the highly microporous nature along with the presence of a few mesopores which facilitates better insertion/de-insertion of Na+ ions; (iii) the Ni-doping which introduces defect sites into the atomic structure of CoO via partial substitution, thus enhancing the conductivity of the cobalt oxide (CoO) component and hence, the overall hybrid material, and (iv) the N-doping which promotes a faster migration speed of sodium ions (Na+) across the carbon layer by creating defect sites, thereby improving the conductivity of the carbon frameworks in the hybrid material.
Co-reporter:Yong Li, Shuan Wang, Yan-Bing He, Linkai Tang, Yusuf Valentino Kaneti, Wei Lv, Zhiqun Lin, Baohua Li, Quan-Hong Yang and Feiyu Kang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 9) pp:NaN4367-4367
Publication Date(Web):2016/11/14
DOI:10.1039/C6TA08611J
Titanium oxide (TiO2) has attracted great interest as a promising anode material for lithium (Li) ion batteries (LIBs) and sodium (Na) ion batteries (SIBs). However, the key factors that dictate the Li-ion and Na-ion storage and transportation in TiO2 remain unclear. Herein, we report a facile hydrolysis route to crafting a variety of high tap-density TiO2 spheres with controllable size and hierarchical pores. The Li-ion and Na-ion storage properties based on these TiO2 spheres were systematically investigated. The pore distribution and the size of TiO2 spheres were found to exert profound influence on the Li-ion and Na-ion storage and transportation. The Li-ion storage and transportation in dense TiO2 spheres was dependent mainly upon the micropore distribution and volume and independent of the size of spheres. In contrast, the excellent Na-ion storage and transportation in TiO2 spheres was enabled by the loose structure with a large macroscopic pore volume and shortened Na-ion diffusion length. High tap-density TiO2 spheres (1.06 g cm−3) with superior Li-ion and Na-ion storage properties were produced, exhibiting a Li-ion storage specific capacity of 189 mA h g−1 at 1C and a high capacity retention of 88.1% after 100 cycles, and a Na-ion storage specific capacity of 184 mA h g−1 at 1C and capacity retention of 90.5% after 200 cycles. The ability to understand the critical factors controlling the Li-ion and Na-ion storage in high tap-density TiO2 spheres enables their implementation for practical applications in Li-ion and Na-ion batteries.
