铈掺杂LiFePO_4的电化学性能研究  

Structure and Electrochemical Properties of Ce-doped Lithium Iron Phosphate

作　　者：刘世斌[1] 李海霞[1] 卫国强[1] 刘惠青[2] 张忠林[1] 郝晓刚[1] 段东红[1] 

机构地区：[1]太原理工大学洁净化工研究所,太原030024 [2]山西广播电视大学,太原030027

出　　处：《太原理工大学学报》2012年第6期641-645,650,共6页Journal of Taiyuan University of Technology

基　　金：国家自然科学基金资助项目(20676088);山西省自然科学基金资助项目(20091402110009)

摘　　要：以Ce为掺杂源,蔗糖为碳源,利用溶胶-凝胶法合成了LiFe1-xCexPO4/C正极材料,并采用SEM、XRD、EIS等分析方法重点考察了不同Ce掺杂量及Ce掺杂同时碳包覆样品的结构及电化学性能。结果表明,所制备的样品均为橄榄石结构,颗粒粒径明显细化。电化学性能测试表明,Ce掺杂量为1%(摩尔分数)时性能最佳,0.1C(C为倍率)放电,其容量可达153.1mAh/g,50次循环后容量保持96.7%;既掺Ce又包覆碳的效果更好,0.1C下其容量可达162.4mAh/g,50次循环后容量几乎没有衰减,1C时其容量可达109mAh/g,表现了良好的倍率性能。EIS测试表明,Ce的掺杂可以明显改善电极表面电化学反应的动力学性能,降低电极/电解液界面电荷转移电阻,Ce掺杂同时碳包覆样品的改善效果更为明显。LiFe1-x CexPO4/C cathode materials were synthesized by the sol gel method using Ce as the dopant source and sucrose as carbon source. Microstructure and electrochemical proper ties of LiFePO4 were investigated using XRD, SEM and EIS measurements. All the samples had the crystal structure of olivine. The particles of synthesized LiFePO4 were fine and homogeneous in size. The electrochemical test shows that the doping of Ce increased the discharge capacity and improved the cycle performance. The research suggests that LiFe0.99 Ce0.01 PO4 exhibited a rela- tively good rate capability and cycling stability. At 0.1C the discharge capacity was 153.1 mAh/ g. After 50 cycles, its discharge capacity remained at 148.0 mAh/g. The discharge capacity of LiFe0.99Ce0.01PO4/C was the best. At 0.1C the discharge capacity was 162.4 mAh/g. The EIS test demonstrates that the doping of Ce improved the cycle performance of the sample, decreased the charge transfer resistance Rct.

关 键 词：磷酸铁锂 溶胶-凝胶法 稀土金属 掺杂改性 碳包覆 

分 类 号：O646[理学—物理化学]