高性能LiFePO_4/C正极材料制备及性能研究  

Synthesis and properties of high-performance LiFePO_4/C cathode material

作　　者：彭刚[1] 杨学林[1] 张露露[1] 段松[1] 温兆银[2] 

机构地区：[1]三峡大学机械与材料学院,湖北宜昌443002 [2]中国科学院上海硅酸盐研究所,上海200050

出　　处：《电源技术》2013年第4期547-549,561,共4页Chinese Journal of Power Sources

基　　金：国家自然科学基金(50972075;51272128);湖北省杰出青年基金(2011CDA093)

摘　　要：以柠檬酸为碳源,采用高温固相烧结工艺制备了一种倍率性能优异的锂离子电池LiFePO4/C正极材料。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)对样品物相和形貌进行表征,通过碳硫分析仪、拉曼光谱仪对不同烧结温度下合成样品中碳含量及结构进行了分析,并对样品的电化学交流阻抗(EIS)和恒流充放电性能进行了测试,探讨了烧结温度对产物电化学性能的影响。结果表明:烧结温度上升导致材料中碳含量及石墨化程度降低,且高温易使颗粒粒径增大,对材料的电化学性能提高不利。700℃合成样品的颗粒分布均匀、碳含量适中,具有最佳的倍率性能。该材料在10C和20 C下,首次放电比容量分别达到110.9和84.5 mAh.g-1,50次循环容量保持率高达98.1%和92.7%。LiFePO4/C composites were successfully prepared by high-temperature solid-state reaction route using citric acid as carbon source. Morphology and phase composition of the as-prepared powders were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. Structure and content of residual carbon in LiFePO4/C sample were analyzed by Raman spectrum and carbon-sulfur determinator respectively. The effect of sintering temperature on the performance of LiFePO4/C was systematically investigated based on electrochemical impedance spectroscopy （EIS） and constant current charge-discharge tests. The experimental results indicate that carbon content of LiFePOJC composite and degree of graphitization of residual carbon decreased with increasing temperature, and higher sintering temperature has detrimental effects on electrochemical performance of LiFePO4/C sample because of larger particle size. The sample synthesized at 700℃ shows the best electrochemical performance with moderate carbon content and uniform particle distribution. The LiFePO4/C electrode can deliver the first discharge specific capacity of 110.9 mAh-g-1 and 84.5 mAh.g-1 at 10 C and 20 C with capacity retention ratios of 98.1% and 92.7% after 50 cycles.

关 键 词：锂离子电池 正极材料 LIFEPO4 固相反应 柠檬酸 

分 类 号：TM912[电气工程—电力电子与电力传动]