Preparation of Li_2FeSiO_4/C Composite Cathode Materials for Lithium Ion Batteries by Carbothermal Reduction Method

摘要

The Li_2FeSiO_4/C composite cathode material was synthesized by carbothermal reduction method using Li_2CO_3, Fe_2O_3 and (C_2H_5O)_4Si and sucrose as raw materials, The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and electrochemical methods. The influence of sintering temperatures on the electrochemical properties of Li_2FeSiO_4/C was examined. The results indicated that the Li_2FeSiO_4 as-synthesized are orthorhombic structure. The highly pure Li_2FeSiO_4 cathode material with uniform and nano-sized particle was synthesized by sintering at 600°C for 12h and showed high specific capacity and good cycle performance. The initial discharge capacity of Li_2FeSiO_4/C composite cathode material was 140.2 mAh/g at 0.2C rate in a potential range of 1.5-4.7V (vs. Li/Li~+) at room temperature, and the discharge capacity was maintained at 141.7 mAh/g after 50 cycles.