Electrochemical studies of carbon coated LiFePO4 doped with tungsten

Abstract

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. LiFe1-yWyPO4 (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.