新一代高比能量锂离子电池富锂氧化物正极材料的研究进展

富锂氧化物xLi_2MnO_3·(1-x)LiMO_2(M为Co、Ni、Mn等)的比容量可达250~300mAh/g,是高比能量锂离子电池正极材料的首选之一。介绍了材料的晶体结构、嵌/脱锂机制和充放电过程中发生的结构相变,分析讨论了材料出现首次不可逆容量大、电压和容量衰减快、倍率性能和低温性能较差等问题的原因,阐述了材料的合成方法及改性技术,如表面包覆、离子掺杂、形貌和晶面调控以及合成层状相-尖晶石相共生结构的异质材料等。最后从基础研究和应用研究两个方面展望了富锂氧化物材料的发展前景。

Li-rich Oxides Cathode Materials:Towards a New Generation of Lithium-ion Batteries with High Energy Density

Li-rich oxides xLi2MnO3 · (1-x)LiMO2 (M=Co,Ni or Mn) with specific capacity of 250-300 mAh/g are promising candidates cathode materials for high specific energy density lithium-ion batteries.In this review,the crystal structure,lithium insertion/extraction mechanism,and structural transformation of Li-rich oxide during the charge-discharge processes are introduced.The issues encountered by the material including the large initial irreversible capacity,fast voltage and capacity fading,as well as the inferior rate capability and low-temperature performance are also illustrated and discussed.Then,the synthesis and modification methods including surface coating,ion doping,morphology and crystal plane control,as well as the fabrication of lamellar phase-spinel intergrown structure for the materials are described.At last,from the view of both basic and applied research,the prospects of future development for Li-rich oxides cathode material are proposed.