Effects of different carbon sources on the properties of LiFePO_4/C composite materials

LiFePO4 and LiFePO4/C cathode materials were synthesized by a solid-state method with a mechanical activation process.The influence of different carbon sources,such as sucrose,citric acid,glucose and tartaric acid on the performances of the material was investigated.The structure,morphology and electrochemical properties of LiFePO4/C were analyzed by XRD,SEM and galvano static charge-discharge method,state of carbon coating was studied by Raman spectra and TEM.The results show that all the samples have the olivine structure,with the additive carbon source,the particle size was reduced and the electronic conductivity was improved by a factor of about 105.The carbon coatings of LiFePO4/C samples are amorphous.The sample used citric acid as the carbon source,with fine particle size and uniformly porous carbon coating,showed excellent electrochemical performances,the third discharge capacity of 141.0mAh/g under 0.1C was obtained with no capacity fading over 10 cycles.