Synthesis and Electrochemical Performances of LiFePO_4/C Composites by Solid State Reduction Method

The LiFePO_4/C composite cathode materials for lithium-ion batteries were synthesized by a solid state reduction method.The crystalline structure,morphology of particles,and electrochemical performance of the sample were investigated by X-ray diffraction,scanning electron microscope,charge- discharge test and cyclic voltammetry.The results show that the composite synthesized at 700℃has a simple pure olive-type phase with small particles,and uniformly distribution of gain sizes,and shows the best electrochemical performances with 1~(st)discharge specific capacity 150.3mAh/g and 20~(th)discharge specific capacity retention ratio 99.2% at 0.1C rate.It also shows good rate capability with 131.4mAh/g, 122.1mAh/g at the high rate of 1.0C and 2.0C,respectively.With the excellent characteristic to re- sist overcharge,this composite can retain its microstructure even after long time overcharge,but it is vulnerable to overdischarge.