•The graphene nanosheets (GNS) were used as the soft template to guide the growth of RF particles. The hierarchical pore structures of RF carbon aerogels (CAs) were maintained and GNS can obviously reinforce the 3D network of carbon aerogels leading to reducing both the carbon shrinkage and composite aerogels density.•By further optimization of loading GO content of GNS/CAs (∼25 wt%), composite CAs with as low density as 23.5 mg cm−3 was obtained, which simultaneously exhibited ultra-high specific surface area (∼3214 m2 g−1).•The resultant composite CAs exhibited high deformation capacitor (∼20.5%), excellent electrical conductivity (∼2.25 Ω−1 cm−1), and extremely low thermal conductivity of 0.027 W m−1 K−1, comparable with that of the pristine CAs.Nanostructural-strengthened carbon composite aerogels were prepared by sol-gel polymerization of resorcinol (R) and formaldehyde (F) with basic catalyst in graphene oxide (GO) aqueous dispersion. Graphene nanosheets (GNS) as soft anti-shrinkage additive, well incorporated into carbon aerogels (CAs) matrix, significantly reinforce the nanostructural skeleton of CAs and effectively inhibit collapse of nanopores and linear shrinkage during carbonization. By further optimization of loading GO content, the resultant GNS/CAs exhibited high surface areas (as high as 3214 m2 g−1) and a low appearance density of 23.5 mg cm−3 at the same time, which are the highest surface areas for GNC/CAs ever reported. In addition, the resultant composite CAs exhibited high deformation capacitor (∼20.5%), excellent electrical conductivity (2.25 Ω−1 cm−1 at a density of 23.5 mg cm−3), and extremely low thermal conductivity of 0.027 W m−1 K−1, comparable with that of the pristine CAs. Together with the easy handling and outstanding electrical/thermal properties, the resulting materials could have further applications such as thermal insulator for thermal protection system and electrode materials.Download high-res image (255KB)Download full-size image

•Unbroken Fe-doped vanadium oxide nanorods were synthesized by a simple hydrothermal method.•Metal ions can enhance the electrical conductivity of electrodes and ion diffusion coefficient.•Fe-doped nanorods (0.15Fe-V2O5) can deliver a good capacity retention rate of 82.2% at 1 A g−1 after 50 cycles.Fe-doped vanadium oxide nanorods were synthesized by a simple hydrothermal method. Experimental results demonstrate that doping moderate amount of metal ions can inhibit the breakage of the morphology structure during phase transition and enhance the structure stability of vanadium oxide nanorods after calcination. Meanwhile, metal ions can enhance the electrical conductivity of electrodes and ion diffusion coefficient, but doping more metal ions can reduce ion diffusion coefficient due to ions block Li+ diffusion path. The unbroken Fe-doped vanadium oxide nanorods play an important role in improving the electrochemical performance of electrodes. Fe-doped nanorods (0.15Fe-V2O5) can deliver a high initial capacity of 271 mA h g−1, and a good capacity retention of 82.2% at a current density of 1 A g−1 after 50 cycles, while un-doped V2O5 electrode materials show a low capacity retention of ∼65.6% under the same condition. Improved performance of Fe-doped vanadium oxides is mainly attributed to the enhancement of electrical conductivity and the maintenance of nanorods structure during electrochemical cycling.

The carbon nanotubes/vanadium oxide composites have been prepared through a facile hydrothermal method. Morphology features of the samples are investigated by field-emission scanning electron microscope. Raman and X-ray diffraction patterns confirm the formation of phase structure. Thermogravimetric analysis was used to quantify the content of carbon nanotube in the composites. When used as cathode materials for lithium-ion batteries, the composites exhibit improved electrochemical performance compared to electrode materials free of carbon nanotubes. V2O5/carbon nanotubes can deliver a good capacity of 196.8 mA h g−1 at a current density of 100 mA g−1 after 50 cycles. However, the electrode materials free of carbon nanotubes (V2O5) can reach a capacity of 171 mA h g−1 at the same conditions. Moreover, V2O5/carbon nanotubes present a higher capacity than that of V2O5 under the same rate conditions. The improved electrochemical performance can be attributed to the fact that the carbon nanotubes in the V2O5/carbon nanotube composites can effectively facilitate ionic diffusion by raising the electrical conductivity.Open image in new window

•A novel hierarchical starfish-like vanadium oxide are synthesized by a simple hydrothermal method.•The functional V2O5 sol plays a crucial role for formation hierarchical starfish-like structure.•Starfish-like vanadium oxide grown along the (1 1 0) plane and four oblique sheets grown on the flanking of (1 1 0) plane, respectively.•Hierarchical starfish-like V2O5 cathode materials can deliver discharge capacity of approximately 163 mA h g−1 at high current density of 1000 mA g−1 (5C) after 50 cyclesA novel hierarchical starfish-like vanadium oxide is synthesized by a simple and direct hydrothermal method using a functional V2O5 sol as a vanadium source. The formation mechanism of hierarchical starfish-like structure is discussed. Results demonstrate that the functional V2O5 sol plays a crucial role in the formation of a hierarchical starfish-like structure. Starfish-like vanadium oxide is composed of single crystals of a metastable VO2 (B) phase that grow along the (1 1 0) plane and four oblique sheets growing on the flanks of the (1 1 0) plane. The starfish-like structure can be preserved and undergoes phase transition to the orthorhombic V2O5 phase when calcined at 350 °C. Hierarchical starfish-like V2O5 displays higher electrochemical performance than pristine V2O5 powder as a cathode material for LIBs. This improved performance could be attributed to the shortened diffusion path of lithium ions in the former; a large electrode/electrolyte contact area resulting from the unique hierarchical starfish-like structure composed of nanosheets also offers better electrolyte wetting and alleviates the structural degradation upon cycling. The hierarchical starfish-like V2O5 can deliver a discharge capacity of approximately 163 mA h g−1 at a high current density of 1000 mA g−1 (5C) even after 50 cycles.

•First of all, a new technique of low cost fabrication of WO3-based gasochromic smart window to reduce the building energy consumption is briefly discussed.•For the first time, the effect of gasochromic smart windows on the energy consumption of building in typical climate regions of China has been calculated and compared with other currently available glazing systems, including SAGE@ electrochromic smart window.•The results indicate that gasochromic smart window can significantly reduce heating and cooling loads in comparison with current static glazing types in all five typical climate zones of China, especially applicable to hot summer and cold winter regions.•At last, the feasibility, potential application areas and the way forward of improvements of gasochromic smart window are discussed.In this paper, first of all, the configuration, optical and thermal properties of WO3-based gasochromic (GC) smart window are briefly reviewed. Subsequently, using the eQUEST building simulation program, the effect of GC smart window on the energy consumption for a commercial office building has been calculated and compared with various glazing systems currently available on the market, including SAGE@ electrochromic (EC) smart window. Simulation results indicate that the hot summer and cold winter regions are the most suitable testing grounds employing smart windows, and the decrease of HVAC loads in shanghai is 28.4% and 11.5% when using GC smart window to replace the single clear float glass and the colored absorbing double glass unit, respectively. Despite the limitation of coloration depth, GC smart window consumes less energy in Harbin than EC does. Also, according to the simulation data, there is no need to change the window’s state hourly unless the occurrence of extreme weather condition.

Vanadium pentoxide (V2O5)/multiwalled carbon nanotube (MWCNT) core/shell hybrid aerogels with different MWCNT contents are controlled synthesized through a facile mixed growth and self-assembly methodology. V2O5 coated MWCNTs from the in situ growth of V2O5 on the surface of acid-treated MWCNTs incorporate with V2O5 nanofibers from the preferred orientation growth of V2O5 in a one-step sol–gel process. These two kinds of one-dimensional fibers self-assemble into a three-dimensional monolithic porous hybrid aerogel. Owing to its high specific surface area, favorable electrical conductivity and unique three-dimensional and core/shell structures, the light weight hybrid aerogel (about 30 mg cm−3) exhibits excellent specific capacitance (625 F g−1), high energy density (86.8 W h kg−1) and outstanding cycle performance (>20000 cycles). And the optimal content of MWCNTs in hybrid aerogels for the highest-performance supercapacitor is 7.6%.

This paper describes the synthesis of a hierarchical porous vanadium pentoxide (V2O5)/graphene hybrid aerogel through a low-cost and facile sol–gel method. The V2O5/graphene hybrid aerogel is synthesized through the in situ growth of V2O5 nanofibers on graphene sheets. The V2O5/graphene hybrid aerogel-based supercapacitors exhibit enhanced specific capacitance (486 F g−1), high energy density (68 W h kg−1) and outstanding cycle performance. These effects are attributed to the unique hierarchical porous structure of the hybrid aerogel.

Urchin-like vanadium oxide nanotube clusters, abbreviated to VOx-NUs, were synthesized using a new method. Vanadium pentoxide, having a layered structure, was modified by lithium fluoride (LiF) and transformed into bi-phase lithium vanadate as the inorganic precursor. Then, VOx-NUs were prepared by hydrothermal reaction with dodecylamine as a template. This is different from other molecular assembly methods reported. VOx-NUs-350 nano clusters were obtained by annealing VOx-NUs at a temperature of 350 °C in air. Both samples were identified as three dimensional urchin-like nano clusters. Based on the characterization data obtained, a formation mechanism was established. By simply varying the LiF stoichiometric ratio, the nano tube density of the VOx-NUs could be controlled. VOx-NUs presented a higher initial rate capacity of 400 mA h g−1 and VOx-NUs-350 maintained a better capacity of 150 mA h g−1 after 50 cycles at a 100 mA g−1 current density between 1.5 and 4 V versus Li/Li+.

Vanadium pentoxide (V2O5) nanosheet thin film without conductive additives and binders has been synthesized via sol–gel and liquid phase deposition methods on ITO glass substrate followed by heat treatment at 450 °C. The SEM and TEM results showed that the as-deposited film presents an intertwined nanowire structure with a length of several micrometers and a width of dozens of nanometers, and it transformed into nanosheet-like crystalline orthorhombic V2O5 after annealing. Possible formation process of the nanowired structure is briefly discussed. The analysis of XRD confirmed that the film exhibits a strong preferred orientation along c-axis. The Raman spectrum verified the layered structure of the film. The corresponding electrochemical performance tests indicated that the binder- and carbon-free film possesses comparable high specific capacity and good cyclic stability to the conventional electrodes, which manifests that this facile synthesized material is quite promising and it provides a low-cost alternative for lithium-ion battery applications.

Highly ordered mesoporous WO3 film was synthesized by employing a template-assisted peroxopolytungstic acid sol–gel method and applied for the first time in gasochromic smart windows. The results demonstrated that this mesoporous microstructured sample with semicrystalline pore walls exhibits excellent performance, including wide optical modulation ability, fast coloring/bleaching response and reliable cyclic stability.

Carbon black (CB) anchored vanadium oxide (C-VOx) nanobelts are successfully prepared by a simple sol–gel route and subsequent hydrothermal treatment. The synthesized C-VOx nanobelts display high specific capacity and good cycling stability as a cathode material for lithium ion batteries (LIBs) (232 mA h g−1 at initial discharge and 195 mA h g−1 during 50th discharge at a current density of 100 mA g−1 between 1.5–4 V versus Li) due to the nano-belted morphology and closely attached CB. The orthorhombic V2O5 nanobelts can be obtained by post-sintering of C-VOx nanobelts in air. These V2O5 nanobelts, which maintain their previous belted morphology and possess higher vanadium valence, exhibit superior electrochemical properties, especially the higher specific capacity (406 mA h g−1 and 220 mA h g−1 during the 1st and 50th discharge at a current density of 100 mA g−1, and 146 mA h g−1 at a current density of 1000 mA g−1 between 1.5–4 V versus Li). Both of them can be used as high performance cathode materials for LIB application. Furthermore, a full-cell using V2O5 nanobelts as the cathode and lithiated graphite as the anode is assembled and its electrochemical performance is measured in the voltage range of 1.5–3.8 V.

The electrochemical and Mg ion diffusion properties of tavorite-Mg0.5FeSO4F were studied by using first principles calculations. A discharge voltage of about 2.52 V versus Mg/Mg2+ corresponding to the redox couples of Fe3+/Fe2+ was predicted for tavorite-Mg0.5FeSO4F, and the experimental diffusion coefficient for the Mg-vacancy in Mg0.5−xFeSO4F is expected to be of the same order of magnitude as that of the Li-vacancy in Li1−xFeSO4F.

The coloration response of gasochromic films is crucial for gas sensors and solar energy cells. Based on a comparison of different post-treatments of WO3 gasochromic films, UV irradiation is found useful for fast coloration, in which fast exponential optical changes can be detected instead of a long activation delay process. Infrared spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy studies show that the gasochromic response of WO3 films depends on the ion and electron diffusion velocities, which can be engineered by altering the film porosities and conductivities. A new gasochromic model is proposed based on a resistor and capacitor (RC) circuit and the double-injection theory. According to this model, the slow coloration delay and fast exponential coloration should result from thermodynamic and electrochemical reactions, respectively. Our new model is also successfully used to build a link between two well-identified theoretical models.

MgVPO4F is proposed as a cathode material for rechargeable Mg ion batteries for the first time. First principles calculations were performed to study the electrochemical properties of MgVPO4F as a positive electrode material for rechargeable Mg ion batteries. Our theoretical study gives an expectation of good battery performance by MgVPO4F.

Bi-crystal lithium vanadate is synthesized with starting materials of V2O5 and LiF by one-step solid-state reaction. Since fluorine reacts with crucible made of silica, Li0.3V2O5-liked and LiV3O8-liked phases without F coexist in the produces. The stoichiometric proportion of two phases depends on the amount of dopant LiF. These are confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and transmission electron microscopy (TEM). Charge and discharge curves of bi-crystal materials present better reversibility of voltage plateaus than that of pure V2O5. The initial discharge capacity of Li0.3V2O5-liked phase dominated bi-crystal material is higher than pure V2O5. LiV3O8-liked phase dominated bi-crystal material has lower initial discharge capacity but delivers better cycling performance. Electrochemical impedance spectroscopy (EIS) measurements are performed to evaluate electrochemical kinetics of the bi-crystal materials. The results indicate that bi-crystal phase benefit the transfer resistance, interior diffusion resistance, and structure stability. Cathodes with different bi-phase structures have variable charge transfer resistance and lithium-ion diffusion speed due to this special structure.

Multiwalled carbon nanotubes (MWCNTs)–V2O5 integrated composite with nanosized architecture has been synthesized through hydrothermal treatment combined with a post-sintering process. During the hydrothermal reaction, protonated hexadecylamine (C16H33NH3+) acts as an intermediator, which links the negatively charged vanadium oxide layer with the mixed-acid pretreated MWCNTs by weak electrostatic forces to form a three-phase hybrid (MWCNTs–C16–VOx). MWCNT–V2O5 composite and V2O5 nanoparticles can be obtained by sintering MWCNTs–C16–VOx at 400 and 550 °C in air, respectively. Among them, MWCNTs–V2O5 possesses better electrochemical performance as a cathode material for lithium ion batteries (LIBs). The unique porous nanoarchitecture of MWCNTs–V2O5 provides a large specific surface area and a good conductive network, which facilitates fast lithium ion diffusion and electron transfer. Additionally, the uniformly dispersed MWCNTs conducting network also behaves as an effective buffer which can relax the strain generated during charge–discharge cycles. Electrochemical tests reveal that MWCNTs–V2O5 could deliver a superior specific capacity (402 mA h g−1 during initial discharge at a current density of 100 mA g−1 between 1.5 and 4 V versus Li/Li+), good cycling stability (222 mA h g−1 after 50 cycles) and high rate capability (194 mA h g−1 at a current density of 800 mA g−1).

•VOx-NTs are prepared by sol–gel method and hydrothermal treatment using dodecylamine as template.•V2O5-NS consisting of interconnected V2O5 nanoparticles is obtained through sintering of VOx-NTs.•V2O5-NS exhibits superior electrochemical performance as cathode material for LIBs.Vanadium oxide nanotubes (VOx-NTs) are prepared by sol–gel method and subsequent hydrothermal treatment using dodecylamines as structure directing templates. After sintering of VOx-NTs in the mixed gas flow of nitrogen and oxygen, we successfully obtain a kind of nanospike shaped vanadium pentoxide free of organic template. The synthesized vanadium pentoxide nanospike (V2O5-NS) is composed of interconnected V2O5 nanocrystals (50–200 nm) and exhibits superior specific capacity and cycling performance (427 mA h g−1 for the first cycle and 218 mA h g−1 after 50 cycles at 50 mA g−1 current density between 1.5 and 4 V versus Li/Li+) when used as cathode materials for lithium ion batteries. Besides, V2O5-NS also possesses good rate capability. This novel method adopted in the work is facile and effective for the synthesis of nanostructured vanadium oxide.

In this paper, MWCNT (Multi-Wall Carbon Nanotube)-induced vanadium oxide nanosheet composite is synthesized via sol–gel method and subsequent hydrothermal treatment process. TEM and SEM tests confirmed that the synthesized product shows a rectangular sheet-like nanostructure with the length of several micrometers, width of a few hundred nanometers and thickness of dozens of nanometers. The analysis of XRD verified the monoclinic crystal structure of the vanadium oxide nanosheet. The XPS results manifested that V4+ is predominant in the V element of vanadium oxide nanosheet. The corresponding electrochemical performance examinations indicated this nanosheet-MWCNT composite with distinct single phase transition feature exhibits high specific capacity and good cycling stability due to its sheet-like nanostructure and uniform adding of MWCNTs, which makes this novel vanadium oxide nanosheet-MWCNT composite quite suitable and promising as cathode material for Li+ ion batteries applications.

Mixed-valence vanadium oxide nanotubes (VOx-NTs) are successfully prepared with dodecylamine as the templates intercalated between VOx layers. A novel ferric ion exchange technique is carried out to remove the amine templates which have no contribution to electrochemical performance of VOx-NTs. TEM observation, XRD study, and FTIR analysis reveal that a large proportion of the amine templates within VOx-NTs can be exchanged by ferric ions in the reaction process, and the tubular morphology and multiwalled structure are not damaged by this exchange technique. Moreover, XPS results indicate that the ferric ion exchange process is also accompanied by the increase of vanadium valence, which is conducive to the improvement of electrochemical capacity of Fe-VOx-NTs. The final synthesized Fe-VOx-NTs exhibit superior specific capacity (311 mAh g–1 at 50 mA g–1 discharge current density in the potential range of 1.5–4 V versus Li/Li+) and cycling performance (178 mAh g–1 after 50 cycles) compared to congeneric modified materials when used as cathode materials for lithium ion batteries.

The gasochromic performance and durability of WO3-based films can be improved by doping SiO2 particles within WO3 matrix forming nanoporous supporting network and dispersing Pd catalyst inside films with enhanced catalytic activity. Nanoporous WO3–SiO2 composite films loaded with Pd catalyst were prepared by sol–gel dip-coating process and served as an active chromogenic layer to fabricate a double-glazed gasochromic device. The structure, morphology, optical properties and gasochromic performance of WO3–SiO2 films were fully investigated. The WO3–SiO2 films exhibit excellent gasochromic performance with ultrafast coloring rate of 14.8% per second (%/s) (WO3: 2.84%/s) and bleaching rate of 44.1%/s (WO3: 7.18%/s). The transmittance changed between 17.8 and 74.6% during coloring-bleaching cycles, and totally reversibility and stability were achieved.Keywords: coloring-bleaching; gasochromic; nanoporous structure; sol−gel process; WO3−SiO2 films;

A new kind of cathode materials for rechargeable lithium-ion batteries, lithium vanadium oxide nanotubes synthesized by a combined sol–gel reaction and hydrothermal treatment procedure is reported in this paper. SEM, TEM, XRD and XPS techniques were performed to investigate the morphology and structure of the resulting materials. The results confirmed that the synthetic materials are composed of uniformly open-ended multiwalled nanotubes with a length from 1 to 3 μm. The inner and the outer diameters of the obtained nanotubes vary from 30 to 50 nm and 50 to 120 nm, respectively. The electrochemical performance as a cathode material was examined and evaluated by cyclic voltammetry, galvanostatic charge–discharge cycling and AC impedance spectroscopy techniques. The results indicated that the resultant lithium vanadium oxide nanotubes have a high initial discharge capacity of 457 mAh g−1 in the potential range of 1.0–4.0 V (vs. Li/Li+) and good cycling performance. The improved electrochemical performance of the products should be due to its special one-dimensional multiwalled tubular structure and the contribution of lithium-ions.

Polypyrrole/vanadium oxide nanotubes (PPy/VOx-NTs) as a new high-performance cathode material for rechargeable lithium-ion batteries are synthesized by a combination of hydrothermal treatment and cationic exchange technique. The morphologies and structures of the as-prepared samples are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetry and differential scanning calorimeter (TG–DSC) and X-ray powder diffraction (XRD). The results indicate that the organic templates are mainly substituted by the conducting polymer polypyrrole without destroying the previous nanotube structure. Their electrochemical properties are evaluated via galvanostatic charge/discharge cycling, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It is found that PPy/VOx-NTs exhibit high discharge capacity and excellent cycling performance at different current densities compared to vanadium oxide nanotubes (VOx-NTs). After 20 cycles, the reversible capacity of PPy/VOx-NTs (159.5 mAh g−1) at the current density of 80 mA g−1 is about four times of magnitude higher than that of VOx-NTs (37.5 mAh g−1). The improved electrochemical performance could be attributed to the enhanced electronic conductivity and the improved structural flexibility resulted from the incorporation of the conducting polymer polypyrrole.

Composites consisting of vanadium oxide nanotubes (VOx-NTs) and polypyrrole (PPy) were synthesized by a two-steps method. VOx-NTs were firstly prepared by a combined sol–gel reaction and hydrothermal treatment procedure, in which V 2O5 powder and H2O2 were used as raw materials and hexadecylamine as a structure-directing template. Then VOx-NTs/PPy composites were fabricated by a cationic exchange reaction between hexadecylamine and polypyrrole. The structure and morphology of the samples were investigated by SEM, TEM, XRD and FTIR techniques. The results confirmed that the template molecules were successfully substituted by the conducting polymers PPy without destroying the previous tubular structure. Electrochemical impedance spectroscopy (EIS) measurements were performed to evaluate the electrochemical kinetics of the samples. The results indicated that VOx-NTs/PPy composites had a lower charge transfer resistance and a faster lithium-ion diffusion speed than those of VOx-NTs, and the enhanced electrochemical kinetics could be attributed to the excellent electronic conductivity of polypyrrole.

Vanadium pentoxide (V2O5)/multiwalled carbon nanotube (MWCNT) core/shell hybrid aerogels with different MWCNT contents are controlled synthesized through a facile mixed growth and self-assembly methodology. V2O5 coated MWCNTs from the in situ growth of V2O5 on the surface of acid-treated MWCNTs incorporate with V2O5 nanofibers from the preferred orientation growth of V2O5 in a one-step sol–gel process. These two kinds of one-dimensional fibers self-assemble into a three-dimensional monolithic porous hybrid aerogel. Owing to its high specific surface area, favorable electrical conductivity and unique three-dimensional and core/shell structures, the light weight hybrid aerogel (about 30 mg cm−3) exhibits excellent specific capacitance (625 F g−1), high energy density (86.8 W h kg−1) and outstanding cycle performance (>20000 cycles). And the optimal content of MWCNTs in hybrid aerogels for the highest-performance supercapacitor is 7.6%.

Highly ordered mesoporous WO3 film was synthesized by employing a template-assisted peroxopolytungstic acid sol–gel method and applied for the first time in gasochromic smart windows. The results demonstrated that this mesoporous microstructured sample with semicrystalline pore walls exhibits excellent performance, including wide optical modulation ability, fast coloring/bleaching response and reliable cyclic stability.

Multiwalled carbon nanotubes (MWCNTs)–V2O5 integrated composite with nanosized architecture has been synthesized through hydrothermal treatment combined with a post-sintering process. During the hydrothermal reaction, protonated hexadecylamine (C16H33NH3+) acts as an intermediator, which links the negatively charged vanadium oxide layer with the mixed-acid pretreated MWCNTs by weak electrostatic forces to form a three-phase hybrid (MWCNTs–C16–VOx). MWCNT–V2O5 composite and V2O5 nanoparticles can be obtained by sintering MWCNTs–C16–VOx at 400 and 550 °C in air, respectively. Among them, MWCNTs–V2O5 possesses better electrochemical performance as a cathode material for lithium ion batteries (LIBs). The unique porous nanoarchitecture of MWCNTs–V2O5 provides a large specific surface area and a good conductive network, which facilitates fast lithium ion diffusion and electron transfer. Additionally, the uniformly dispersed MWCNTs conducting network also behaves as an effective buffer which can relax the strain generated during charge–discharge cycles. Electrochemical tests reveal that MWCNTs–V2O5 could deliver a superior specific capacity (402 mA h g−1 during initial discharge at a current density of 100 mA g−1 between 1.5 and 4 V versus Li/Li+), good cycling stability (222 mA h g−1 after 50 cycles) and high rate capability (194 mA h g−1 at a current density of 800 mA g−1).

This paper describes the synthesis of a hierarchical porous vanadium pentoxide (V2O5)/graphene hybrid aerogel through a low-cost and facile sol–gel method. The V2O5/graphene hybrid aerogel is synthesized through the in situ growth of V2O5 nanofibers on graphene sheets. The V2O5/graphene hybrid aerogel-based supercapacitors exhibit enhanced specific capacitance (486 F g−1), high energy density (68 W h kg−1) and outstanding cycle performance. These effects are attributed to the unique hierarchical porous structure of the hybrid aerogel.

Carbon black (CB) anchored vanadium oxide (C-VOx) nanobelts are successfully prepared by a simple sol–gel route and subsequent hydrothermal treatment. The synthesized C-VOx nanobelts display high specific capacity and good cycling stability as a cathode material for lithium ion batteries (LIBs) (232 mA h g−1 at initial discharge and 195 mA h g−1 during 50th discharge at a current density of 100 mA g−1 between 1.5–4 V versus Li) due to the nano-belted morphology and closely attached CB. The orthorhombic V2O5 nanobelts can be obtained by post-sintering of C-VOx nanobelts in air. These V2O5 nanobelts, which maintain their previous belted morphology and possess higher vanadium valence, exhibit superior electrochemical properties, especially the higher specific capacity (406 mA h g−1 and 220 mA h g−1 during the 1st and 50th discharge at a current density of 100 mA g−1, and 146 mA h g−1 at a current density of 1000 mA g−1 between 1.5–4 V versus Li). Both of them can be used as high performance cathode materials for LIB application. Furthermore, a full-cell using V2O5 nanobelts as the cathode and lithiated graphite as the anode is assembled and its electrochemical performance is measured in the voltage range of 1.5–3.8 V.