Preparation And Electrochemical Performance Of V₂O₅ Nanoparticles

V2O5 has received extensive attention because of its high theoretical capacity, high discharge platform, convenient synthesis, low cost and so on.But it also exists some disadvantages, such as poor structure stability,, the practical application of V2Os has been hindered due to low ionic and electronic conductivity, during the process of charging and discharging, the intercalation/de-intercalation of Li+will lead to the collapse of the layered structure of V2O5. The nanometer material and metal cation doping can effectively overcome the disadvantages of V2O5 materials. This paper prepared pure V2O5 nanomaterials and metal ion doping of V2O5 nanomaterials, and characterized the morphology, structure, electrochemical performance and the influence of metal ion doping on the properties of the material. The main work is summarized as follows:Firetly, a mixed solvent hydrothermal process was used to synthesize nano-structured vanadium oxides. The morphology and crystal structure were analyzed using scanning electron microscope (SEM) and x-ray diffraction (XRD). The electrochemicalperformances were measuered by cyclic voltammogram (CV) and galvanostatic charge-discharge. Mainly to explore the different preparation conditions, composition of solvent, hydrothermal temperature, packing ratio, hydrothermal time. The best preparation conditions were obtained, as shown below:water and ethanol volume was 1:0.5, hydrothermal temperature was 180 ?, packing ratio was 60%, hydrothermal time was 24h, the best solvent was ethanol. And this material showed better electrochemical performance:better reversibility, rate performance and cycling performance. At 0.1C rate of charge and discharge test, the initial discharge specific capacity can reach 250.01mAh/g.Secondly, vanadium oxides materials with nano rod structure were synthesized by using NH4VO3 and HCl as raw materials. The morphology and crystal structure were analyzed using scanning electron microscope (SEM) and x-ray diffraction (XRD). The electrochemicalperformances were measuered by cyclic voltammogram (CV) and galvanostatic charge-discharge. Mainly to explore the different preparation conditions, (such as pH, hydrothermal temperature, hydrothermal time, packing ratio and surfactant). The best preparation conditions were obtained, as shown below:pH was 3, the hydrothermal temperature was180?, hydrothermal time was 24h and packing ratio was 70%, the surface active agent was added can improve electrochemical performance of V2O5 material. Under the above conditions, V2O5 material had better electrochemical performance, good reversibility, high rate performance and cycling performance. At 0.1C rate of charge and discharge test, the initial discharge specific capacity can reach 245.89mAh/g.Finally, we studied the effect of metal ion doping. The morphology and crystal structure were analyzed using scanning electron microscope (SEM) and x-ray diffraction (XRD). The electrochemicalperformances were measuered by cyclic voltammogram (CV) and galvanostatic charge-discharge. The results were showed that:metal ions doping can obviously improve the electrochemical performance of V2O5. When the doping amount was 1:0.03, the capacity of the first charge and discharge can be as high as 350.68mAh/g, its value was higher than the theoretical capacity when two Li+intercalation, the rate performance and cycle performance of V2O5 were higher than without ion doped materials.