Synthesis and electrochemical performance of lithium vanadium phosphate and lithium vanadium oxide composite cathode material for lithium ion batteries

A novel 2Li3V2(PO4)3·LiV3O8 composite with short rod and thin plate shapes is synthesized through sol-gel method followed by hydrothermal and solid-state reaction. LiV3O8 is used as an additive to improve the capacity of Li3V2(PO4)3. In the composite cathode, active impurity phase Li0.3V2O5 is also present, which has little impact on the whole electrochemical properties. The 2Li3V2(PO4)3·LiV3O8 composite delivers a high initial capacity of 162.8 mAh g−1 at a current density of 100 mA g−1 in the voltage range of 2.0-4.3 V. Furthermore, the composite with high crystallinity also shows high electrochemical reversibility and good rate capability. The diffusion coefficient of Li ions in the composite is in the range of 10−11-10−9 cm2 s−1 obtained from galvanostatic intermittent titration technique.