The synthesis of lithium vanadium phosphate cathode material with high electrochemical performance

Abstract： The VO2 nanorods were prepared with V2O5 by hydrothermal method. Polypyrrole was coated on the surface of VO2 through in-situ polymerization. The VO2 particles coated with polypyrrole were mixed with NH4H2(PO4)3 and Li2CO3 in ethyl alcohol according to the stoichiometry of Li3V2(PO4)3 to synthesize the cathode material Li3V2(PO4)3/C. Polypyrrole coated on the surface of VO2 nanorods was carbonized in the process of calcination to inhibit the growth of Li3V2(PO4)3 grains. A battery was assembled with Li3V2(PO4)3/C (cathode) and lithium metal (anode) to test the electrochemical performance of cathode material. The constant current charge/discharge cycling performance was measured in the potential range of 3.0-4.3 V. The discharge capacities were 130, 125, 123 and 115 mAh g-1 at the rates of 0.2, 1.0, 2.0 and 5.0 C, respectively. And the discharge specific capacity was 121 mAh g-1 after 600 cycles at 1.0 C, meaning the discharge specific capacity retention rate was as high as 96 %. The grain refinement enhances the electrochemical performance of Li3V2(PO4)3/C.