锂离子电池用富锂正极材料的研究进展

Progress of Lithium Rich Cathode Materials for Li-Ion Batteries

富锂材料xLi2MnO3.(1-x)LiMO2(0<x<1,M=Mn,Co,Ni)的高比容量(≥250 mAh·g-1)和低廉的价格已引起人们的广泛兴趣.但其首次充放电循环的较大不可逆容量损失、较差的倍率性能和循环过程的材料相变等关键问题制约了其发展.富锂材料结构解析和充放电机理探索一直是研究的热点.目前,富锂材料是否为固溶体仍有争论,首次充电4.5 V平台的氧流失机理已得到确认.为了提高富锂材料的电化学性能,可从体相掺杂、表面包覆和结构形貌控制等方面对材料进行改性,其电化学性能有显著提升.本文综述了富锂材料最新研究进展,归纳了相关制备方法,重点介绍了富锂材料的结构特点、锂嵌脱机理和改性方法,并展望了今后的研究方向.

Lithium rich materials xLi2MnO3.（1-x）LiMO2（0x1,M=Mn,Co,Ni）become a hot topic because of their high capacities exceeding 250 mAh.g-1and low cost.However,the large irreversible capacity during the first cycle,low rate capability and structure collapse during cycling remain impediments in developing these cathodes for applications.The structure analyses and charge/discharge mechanisms for lithium rich materials are currently main research contents.Although whether the lithium rich materials are solid solutions or composite is still controversial,oxygen release mechanism on the first charge 4.5 V plateau of lithium rich materials has come to consistency.Several modifications,such as bulk doping,surface coating and microstructure control,demonstrate promising strategies to obviously improve electrochemical properties.The structure,charge/discharge mechanism,synthesis methods and electrochemical modifications of lithium rich cathode materials are systematically reviewed in this article.Further research aspects of these kinds of materials as cathode materials for lithium ion batteries are also discussed.