Study On The Preparation And Performance Of V₂O₅Films As Cathode Materials For Li-ion Batteries

V₂O₅has become a very promising anode material for Li-ion batteries due to itshigh theoretical lithium intercalation capacity, abundant resources and cheap price.However, the widespread application of V₂O₅was limited in Li-ion batteries because ofpoor stability of structure and low conductivity of electron。In this work, the V₂O₅filmsmaterials were prepared by electrodeposition and sol-gel method respectively, and theelectrochemical performances of V₂O₅films materials were researched systematically inorder to improve the lithium insertion performance of V₂O₅anode material in Li-ionbatteries.Firstly, the structures of V₂O₅films prepared by electrodeposition werecharacterized by XRD, SEM and TG-DTA. The results showed that the V₂O₅films werechanged from amorphous into orthorhombic crystalline while calcining at500℃in theair, the crystal form of V₂O₅was changed over400℃according to TG-DTA, and V₂O₅films was made of the uniform, dense nanoparticles with the size of340nm and thethickness of8μm showed by SEM. However, the particles size and films thickness ofV₂O₅was reduced after used as cathode materials for Li-ion batteries.Secondly, the effect of preparation conditions on electrochemical performance ofthe V₂O₅films was studied by cyclic voltammetry and chronopotentiometry. Theresearch results showed that the best electrochemical performances was carried outwhen V₂O₅films was prepared with electrodeposition time of10min and calcined at500℃in air for1h. The V₂O₅films demonstrated a high initial discharge capacity of536.29mAh/g with a current density of12.5μA/cm², and the discharge capacity of480.76mAh/g after10cycles, with the capacity fading rate of10.35%. Another V₂O₅films sample prepared under the same conditions had the initial discharge capacity of505.34mAh/g, the corresponding charging capacity of470.84mAh/g and the irreversiblecapacity of34.5mA h/g with a current density of12.5μA/cm². The sample still remainedthe discharge capacity of385.70mAh/g after50cycles, with the capacity fading rate of23.68%.Finally, the V₂O₅films were prepared by sol-gel method and electrochemicalperformances were researched. The results showed that the V₂O₅films prepared byadding1.4%PVP and calcined at500℃in air for2h, demonstrated the bestelectrochemical performances. With the current density of7.75μA/cm², the V₂O₅films had the initial discharge capacity of85.11mAh/g, the discharge capacity of80.28mAh/gafter10cycles, with the capacity fading rate of5.68%.