Non-stoichiometric synthesis and electrochemical performance of LiFe 1-x PO 4 / C cathode materials for lithium ion batteries

Non-stoichiometric LiFe 1-x PO 4 / C composites were synthesized by a simple sol–gel method. Different impurities were detected in the X-ray diffraction measurements with the change of Fe content. The effects of Fe -poor on the structure and electrochemical performance of LiFePO 4 were investigated. Compared with stoichiometric LiFePO 4 / C , non-stoichiometric samples show better electrochemical performance because they have smaller impedance and faster lithium ion diffusion. Among these non-stoichiometric samples, LiFe 0.94 PO 4 / C cathode delivers the highest capacity of 149 mAh g -1 at 0.2 C and 103 mAh g -1 at 5 C and no capacity loss was found after 100 full cycles.