铝掺杂LiFePO_4的表面成分结构及电化学性能研究  

Surface Composition Structure and Electrochemical Performance of Aluminum Doped LiFePO_4

作　　者：尚怀芳[1] 黄伟峰[2] 储旺盛[2] 夏定国[3] 吴自玉[2] 

机构地区：[1]北京工业大学环境与能源工程学院环境电化学实验室,北京100717 [2]中国科技大学国家同步辐射实验室,安徽合肥230026 [3]北京大学工学院先进电池材料理论与技术北京市重点实验室,北京100871

出　　处：《电化学》2013年第6期558-564,共7页Journal of Electrochemistry

基　　金：国家自然科学基金项目(No.11179001);北京市自然科学基金项目(No.20110001);国家高技术研究发展863计划项目(No.2011AA11A254;No.2012AA052201)资助

摘　　要：锂离子电池正极材料掺杂LiFePO4的报道已很多,而涉及掺杂LiFePO4的表面成分及结构的研究仍很少见.本文采用溶剂热法一步制得了表面富Al的LiFePO4正极材料.TEM测试证实LiFePO4的表面形成均匀的无定型包覆层;俄歇电子能谱和软X射线吸收谱均表明其表面的包覆层为部分Al替代Fe的LiFe1-x Alx PO4.表面富Al（x=0.02）的LiFePO4显示了较好的电化学倍率性能和低温性能,-10℃下充放电,电压范围2.2-4.2 V、0.1C倍率,电极的放电比容量为98 mAh·g-1,0.5C倍率放电比容量可达70 mAh·g-1.这归因于Al的加入改变了材料体相及表面的电子结构,增加了体相电子的传导及表面离子的传导.Despite there are many successful reports about the preparation of electrode materials with surface coating for lithium ion batteries, the study in surface self-coating of cathode materials using segregation of doping elements and their electrochemical properties is still very rare. The LiFePO4 particles with rich-Al on the surface were synthesized by one step solvothermal route. TEM results demonstrated that the surface of the obtained LiFePO4 particles was well-covered by the amorphous coating. The soft X-ray absorption spectroscopy and Auger electron spectroscopy（AES） component analyses reveal that the amorphous coating was composed of LiFe1-x Alx PO4 by part of Al substitution to Fe. The LiFePO4 material with surface rich-Al showed good electrochemical rate capacity and low temperature performance. This could be attributed to the changes of the bulk and surface electron structure which promote the bulk electron and surface ionic conductivities.

关 键 词：LIFEPO4 表面包覆 电化学性能 

分 类 号：TM912[电气工程—电力电子与电力传动]