Improved electrochemical performances of 9LiFePO4·Li3V2(PO4)/C composite prepared by a simple solid-state method

9LiFePO4·Li3V2(PO4)3/C is synthesized via a carbon thermal reaction using petroleum coke as both reduction agent and carbon source. The as-prepared material is not a simple mixture of LiFePO4 (LFP) and Li3V2(PO4)3 (LVP), but a composite possessing two phases: one is V-doped LFP and the other is Fe-doped LVP. The typical structure enhances the electrical conductivity of the composite and improves the electrochemical performances. The first discharge capacity of 9LFP·LVP/C in 18650 type cells is 168 mAh g−1 at 1 C (1 C9LFP·LVP/C = 166 mA g−1), and exhibits high reversible discharge capacity of 125 mAh g−1 at 10 C even after 150 cycles. At the temperature of −20 °C, the reversible capacity of 9LFP·LVP/C can maintain 75% of that at room temperature.