LiFePO4/C正极材料的液相合成及电化学性能研究

尝试对共沉淀法进行改进, 利用自制的加料装置合成了橄榄石型LiFePO₄/C复合正极材料. 应用X射线衍射(XRD)、扫描电镜(SEM)、X射线能谱(EDS)、循环伏安(CV)以及恒电流充放电测试等方法对目标材料进行了结构表征和电化学性能测试. 实验结果表明采用该法得到的样品具有单一的橄榄石结构, 样品形貌规则, 粒径细小均匀. 改性后的材料具有较高的首放容量及良好的循环稳定性能. 0.1C倍率下充放电测试表明, 其首次放电比容量超过145 mAh?g^－1, 50次循环后, 容量没有明显衰减. 0.2C和0.5C倍率下的平均放电容量分别为130及120 mAh?g^－1, 循环过程中样品表现出较好的循环稳定性.

Synthesis of LiFePO4/C Cathode Material through a Solution-phase Approach and Its Electrochemical Performance

Attempt was made for the first time to improve the co-precipitation method by designing a feed-in device to synthesize the olivine LiFePO₄/C composite cathode material. The crystal structure and the electrochemical performance were characterized by XRD, SEM, EDS, cycle voltammetry and galvanostatical charge-discharge testing. The material has a single crystal olivine structure with homogeneous grain sizes and shows a good electrochemical performance. The galvanostatical charge and discharge tests showed that the material gave a reversible specific capacity of 145 mAh?g^－1 at 0.1C discharge rate. After 50 cycles, there was no obvious capacity fading. The average capacities of LiFePO₄/C material at 0.2C and 0.5C were 130 and 120 mAh?g^－1, respectively. The material exhibited excellent cyclic performance.