Effect of Carbon Sources on the Battery Properties of LiFePO4/C Cathode Materials Prepared by Spray Pyrolysis

Abstract

LiFePO4/C cathode materials were prepared by spray pyrolysis, and the effect of carbon source and calcination condition on powder characteristics and battery properties of the materials were studied. Homogeneous olivine LiFePO4 powders were formed from all carbon sources, and carbon contents of LiFePO4/C particles prepared from fructose or sucrose were high due to their high pyrolysis temperature. Particle morphology was changed according to carbon source, and crystal growth was promoted by increasing calcination temperature. Carbon layers were observed on the surface of LiFePO4/C particles. Battery properties were improved by increasing carbon content of LiFePO4/C particles, but the properties also depended largely on their particle size. So it revealed that the discharged capacity of LiFePO4/C cathode was maximized when both their carbon content and particle size showed optimum value. The discharged capacity of LiFePO4/C cathode prepared from sucrose exhibited 153 mAh/g at 1 C when it was calcined at 750°C for 3 hr.