关键词: LiFePO₄, 原位分解, 循环稳定性, 烧结温度, 放电容量

Abstract: LiFePO₄/C was synthesized by a sol-gel method using glycol as solvent. X-ray diffraction and scanning electron microscope were used for the phase identification and the structural observation of the synthesized LiFePO₄ products. The electrochemical properties including the cycle stability, the discharge capacity under different discharge rates of LiFePO₄ synthesized at 600--750℃ were investigated by means of electrochemical impedance spectroscope and other methods. The results show that the crystallization and electrochemical performance of LiFePO₄/C are affected remarkably by the sintering temperature. LiFePO₄/C sintered at 700℃ is well crystallized and has an even distribution of gain with size of around 150nm, exhibiting excellent electrochemical properties. Its discharge capacity reaches 150mAh/g at 0.5C and the discharge capacity still reaches 141mAh/g at 1C. The discharge capacity of the LiFePO₄/C is almost reserved after 200 cycles.

Key words: LiFePO₄, in situ decomposition, cycle stability, sintering temperature, discharge capacity