Yu Haijun, So Yeong-Gi, Ren Yang, Wu Tianhao, Guo Gencai, Xiao Ruijuan, Lu Jun, Li Hong, Yang Yubo, Zhou Haoshen, Wang Ruzhi, Amine Khalil, Ikuhara Yuichi
College of Materials Science & Engineering, Key Laboratory of Advanced Functional Materials, Ministry of Education , Beijing University of Technology , Pingleyuan #100 , Chaoyang District, Beijing , 100124 , People's Republic of China.
Institute of Engineering Innovation, School of Engineering , The University of Tokyo , Tokyo 113-8656 , Japan.
J Am Chem Soc. 2018 Nov 14;140(45):15279-15289. doi: 10.1021/jacs.8b07858. Epub 2018 Nov 1.
Cathodes of lithium-rich layered oxides for high-energy Li-ion batteries in electrically powered vehicles are attracting considerable attention by the research community. However, current research is insufficient to account for their complex reaction mechanism and application. Here, the structural evolution of lithium-manganese-rich layered oxides at different temperatures during electrochemical cycling has been investigated thoroughly, and their structural stability has been designed. The results indicated structure conversion from the two structures into a core-shell structure with a single distorted-monoclinic LiTMO structure core and disordered-spinel/rock salt structure shell, along with lattice oxygen extraction and lattice densification, transition- metal migration, and aggregation on the crystal surface. The structural conversion behavior was found to be seriously temperature sensitive, accelerated with higher temperature, and can be effectively adjusted by structural design. This study clarifies the structural evolution mechanism of these lithium-rich layered oxides and opens the door to the design of similar high-energy materials with better cycle stability.
用于电动车辆中高能锂离子电池的富锂层状氧化物阴极正受到研究界的广泛关注。然而，目前的研究不足以解释其复杂的反应机理和应用。在此，对富锂锰层状氧化物在不同温度下电化学循环过程中的结构演变进行了深入研究，并对其结构稳定性进行了设计。结果表明，结构从两种结构转变为具有单一畸变单斜LiTMO结构核和无序尖晶石/岩盐结构壳的核壳结构，同时伴随着晶格氧的析出、晶格致密化、过渡金属迁移以及在晶体表面的聚集。发现结构转变行为对温度非常敏感，温度越高加速越快，并且可以通过结构设计有效调节。本研究阐明了这些富锂层状氧化物的结构演变机理，为设计具有更好循环稳定性的类似高能材料打开了大门。
