不同碳源掺杂磷酸亚铁锂正极材料电化学性能研究

Electrochemical performance study of LiFePO4 cathode material in different carbon resources doping

采用液相共沉淀-固相焙烧合成了橄榄石型磷酸亚铁锂(LiFePO4)正极材料,用X射线衍射(XRD)、扫描电镜(SEM)和恒流充放电测试等方法对产物物相结构、表观形貌和电化学性能进行了表征和分析。纯相材料首次放电比容量达到90.6 mA.h/g,循环5次后,放电比容量为75.94 mA.h/g。为解决首次放电比容量低下以及材料循环性能差的问题,采取不同碳源掺杂对材料进行改进,最后得到L iFePO4/C复合正极材料,0.05 C首次放电比容量达到158.8 mA.h/g。

Olivine type LiFePO4 cathode material was synthesized by liquid - phase co - precipitation - solid phase calcination. The crystalline structure, morphology and the electrochemical performances of the product were characterized and analyzed by X - ray diffraction （ XRD）, scanning electron microscopy （ SEM } and galvanostatic charge - discharge test. The first discharge specific capacity of the homogeneous material was 90. 6 mA·h/g. After 5 cycles, it reduced to 75.94 mA·h/g. To enhance the initial discharge capacity and to improve the cycle capability, different kinds of carbon resources were used to synthesize the doped samples. Finally the LiFePO4/C composite cathode material was obtained, and its initial discharge specific capacity reached 158.8 mA·h/g at 0.05 C charge/discharge rate.