Hydrothermal Synthesis And Performance Of V₂O₅ Thin Film Electrode

Vanadium pentoxide?V₂O₅?has become a very promising cathode material for Li-ion batteries due to its advantages of high theoretical capacity,high energy density,abundant lithium and low price.However,the application of V₂O₅ was limited in Li-ion batteries for its poor structural stability,low electron conductivity and small lithium ion diffusion coefficient.V₂O₅ thin film cathode was synthesized by a simple and easy operation hydrothermal method in this paper,and the structures and morphologies were characterized by XRD and SEM,electrochemical performancewas tested by cyclic voltammetry and chronopotentiometry.Analysis from XRD,SEM showed that the V₂O₅ thin film cathodes synthesized by different experimental conditions were orthorhombic layered structures,but they had a large difference in the microstructure.The microstructure of V₂O₅ changed from 1D to 3D with the increase of hydrothermal time.Turbine-like nanoflower structure V₂O₅ with diameter of 8¹0 ?m and thickness of 2⁴ ?m was obtained under 5h hydrothermal time.Turbine-like nanoflower V₂O₅ with diameter of 8¹0 ?m and a large number of V₂O₅ nanoparticles with a diameter of about 300 nm were embedded in the turbine blade gap were obtained under CTAB addition.Results from electrochemical performance test showed that the initial discharge capacity of the V₂O₅ thin film cathode with the increase of hydrothermal time and surfactant addition indicated a tendency to increase first and then decrease,and the V₂O₅ thin film cathode under the conditions of 5h hydrothermal time and 4.27% CTAB addition showed the best electrochemical performance.The prepared V₂O₅ thin film cathode demonstrated a high initial discharge capacity of 237 mAh/g with the current denisity of 200 ?A/cm2,and the discharge capacity maintain more than 90% after 35 cycles.The initial discharge capacity was as high as 297 mAh/g at a lower current denisity of 100 ?A/cm2,the discharge capacity of 154 mAh/g after 30 cycles with increasing the current density to 600 ?A/cm2,and the discharge capacity can be stable at 210 mAh/g with the current density back to 100 ?A/cm2 after 36 cycles,still have 70% of the discharge capacity to maintain,showed an excellent rate capability.In conclusion,The V₂O₅ thin film cathode synthesized by hydrothermal method under the conditions of 5h and 4.27% CTAB addition have orthorhombic structure,the morphology of turbine-like nanoflower and a large number of nanoparticles showed a large specific surface area of the active substance,and then make electrolyte and electrode materials with full contact,shorten the diffusion path of Li+,which greatly improves the charge and discharge capacity and cycle stability,electrochemical performance of the V₂O₅ thin film cathode can be greatly improved.