Electrochemical studies of carbon coated LiFePO4 doped with tungsten

摘要

Due to its high thermal stability, low cost and high theoretical charge capacity, LiFePO₄ has emerged as one of the most promising cathode materials for large-scale lithium ion batteries. In this work, we systematically investigated the effect on structure and electrochemical properties brought by W doping on Fe site of LiFePO₄. LiFe_1-yW_yPO₄ (y = 0. 0.01, 0.02, 0.03) samples with carbon coating were prepared by using solid-state reaction. The phase and structure of as prepared powders were characterized by X-ray diffraction. Cycling charge and discharge measurement at various C-rates, cyclic voltammetry and electrochemical impedance spectroscopy were employed to reveal the electrochemical properties. Results showed that carbon coating dramatically improved the capacity at fast C-rate. The sample with 2% W doping and carbon coating was observed to have the highest charge capacity of 146 mAhg^-1 at 0.1C and 110 mAhg^-1 at 1C.