Olivine LiFePO₄/C composite cathode materials were synthesized by a solid state method in an inert atmosphere. The crystal structure and the electrochemical performance were characterized by XRD, SEM, laser particle-size distribution measurement and electrochemical performance testing. The effects of different carbon source, such as dextrose, acetylene black and graphite, on the performance of as-synthesized cathode materials were investigated and the causes also analyzed. The results demonstrated that the composite material carbon-doped by dextrose had the most excellent electrochemical performances. The initial discharge capacity, namely 142.5 mAh/g, was delivered at room temperature and C/20 discharge rate. After 30 cycles, the capacity fade was only 2.5%.

Key words: carbon source, lithium iron(II) phosphate, olivine, cathode material