Effects of Preparation Temperature on Pyrolytic Carbon Coated LiFePO_4/Vapor-grown Carbon Fiber (PCLFP/VGCF) Composite Cathode Material

Pyrolytic carbon coated LiFePO4/vapor-grown carbon fiber(PCLFP/VGCF) composite cathode materi-als were prepared by microwave chemical vapor deposition(MCVD) process.Effects of preparation temperature on microstructures and electrochemical properties of the composites were investigated.The results show that with preparation temperature increasing from 500℃ to 600℃,the discharge capacities of the composite electrodes are improved because of the gradual formation of conductive network of VGCF.However,it decreases when the preparation temperature is up to 700 ℃,which may be attributed to the exaggerated grain growth of LiFePO4 and the reduction of VGCF network.In addition,the composite cathode materials prepared at 600℃ show better elec-trochemical properties,with the discharge capacity as high as 163,159,153 and 143mAh/g at rate of 0.2C,0.5C,1C,3C,respectively(25 ℃).