Mg掺杂对LiFePO_4材料电化学性能的影响  

Influence of the Mg-substitution on electrochemical performances of LiFePO4

作　　者：胡环宇[1] 仇卫华[1] 李发喜[1] 赵海雷[1] 王碧燕[1] 

机构地区：[1]北京科技大学材料科学与工程学院无机非金属材料系,北京100083

出　　处：《电源技术》2006年第1期18-20,共3页Chinese Journal of Power Sources

基　　金：国家自然基金资助项目(50272012)

摘　　要：采用固相反应法合成了锂离子蓄电池正极材料LiFePO_4。为了改进LiFePO_4的高倍率充放电性能,我们采用Mg对其进行了体掺杂。通过示差扫描量热分析(DSC)、X射线衍射(XRD)分析以及电化学测试等手段,研究了Mg掺杂对材料的结构和电化学性能的影响。研究结果表明,Mg的加入不仅会提高材料的比容量,而且还降低了材料在充放电过程中的极化电位。但在Mg替代Fe的同时,材料的晶胞体积减小,可能会造成离子导电的降低。研究发现,当Mg的掺杂量为10%(摩尔百分数)时,材料表现出较优的电化学性能,比容量可以提高到129mAh/g。当Mg掺杂量达到20%时,比容量下降到108mAh/g,且高倍率性能较差。In order to improve the rate capability, the Mg-substituted LiFePO4 prepared by solid-state reaction was studied. Influence of Mg substitution on structure and electrochemical performances of LiMgxFe1-xPO4 material were investigated by means of DSC,XRD and charge-discharge tests. The doping of Mg could not only increase the capacity but also hold down the polarization in cycling processes. The lattice volume decreased when the Mg content increased, which made Li ionic conductivity reduce. When x was 10%, the doped material showed excellent electrochemical properties, with the discharge capacity as high as 129 mAh/g. However, when x reached 20%, it exhibited deteriorated high rate capability.

关 键 词：锂离子蓄电池 LIFEPO4 Mg掺杂 

分 类 号：TM912.9[电气工程—电力电子与电力传动]