Preparation and characterization of LiFePO4·xLi3V2(PO4)3 composites by two-step solid-state reaction method for lithium-ion batteries

LiFePO4·xLi3V2(PO4)3 (LFP·xLVP, x = 0, 0.05, 0.1, 0.15, 0.2) composites were prepared by the two-step solid-state method. The structure, morphology and electrochemical properties were characterized by X-ray diffraction, scanning electron microscope, cyclic voltammetry, charge-discharge performance test and electrochemical impedance spectroscopy. It was indicated that composites were presented rough in surface of ball-like particles. Two phase of LFP and LVP combination improved electrochemical properties of LFP. The LFP·0.1LVP has the highest discharge capacity of 154 mAh/g at 0.2 C. Compared with LFP, the rate performance of the LFP·0.1LVP increased 13% and 8% at 1 C and 10 C after five cycles. It possessed excellent cycle life of 99.8% after 100 cycles at 1 C especially. The all preparation process without any solvent addition was easy operation, energy saving and environmentally friendly.