Influence of surface modification by vanadium oxide and carbon on the electrochemical performance of LiFePO4/C

摘要

Surface modification with metal oxides is an efficient method to improve the performance of LiFePO4. Carbon and V2O3 co-coated LiFePO4 is synthesized by carbothermal reduction method combined with star-balling technique, and vanadium oxide is produced in situ. The structure and pattern of LiFePO4/C modified with different amounts of vanadium oxide (0-5 mol%) were studied by Xray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and micro-Raman spectroscopy. The electrochemical performance of material electrodes was analyzed by constant current charge-discharge and electrochemical impedance spectra (EIS). Electrochemical test results show that sample B (1.0 mol%) exhibits the best electrochemical performance, whose discharge capacity is up to 160.1,127.2, and 88.4 mAhg~(-1) at 1, 5, and 10 °C, respectively. It indicates that V2O3 modification efficiently improves specific capacity and rate capability. The EIS experiment demonstrates that catalytic activity and reversibility of the cathode electrode are obviously increased by the surface modification of vanadium oxide.