Structural origin of the high-voltage instability of lithium cobalt oxide
Structural origin of the high-voltage instability of lithium cobalt oxide
复制标题
钴酸锂高电压不稳定性的结构根源
DOI：
10.1038/s41565-021-00855-x
复制
发表时间：
2021-02-22
影响因子：
38.3
通讯作者：
Pan, Feng
中科院分区：
文献类型：
--
作者：
Li, Jianyuan;Lin, Cong;Pan, Feng
层状锂钴氧化物（LiCoO 2，LCO）是锂离子电池中最成功的商用正极材料。然而，在高于4.35 V（相对于Li/Li+）的电位下，其显著的结构不稳定性构成了获得其理论容量274 mAh g−1的主要障碍。虽然已经发现并商业化了一些高压LCO（H-LCO）材料，但其稳定性的结构来源仍然难以确定。在这里，使用三维连续旋转电子衍射方法辅助辅助高分辨率透射电子显微镜，我们研究了两种商业LCO材料：正常LCO（N-LCO）和H-LCO之间的原子水平的结构差异。这些强大的工具表明，在表面附近发生的钴氧化物层的曲率决定了材料在高电位下的结构稳定性，进而决定了电化学性能。在理论计算的支持下，这种对层状LCO材料的结构-性能关系的原子理解为未来设计在高电压下具有上级结构稳定性的新阴极材料提供了有用的指导。
Layered lithium cobalt oxide (LiCoO2, LCO) is the most successful commercial cathode material in lithium-ion batteries. However, its notable structural instability at potentials higher than 4.35 V (versus Li/Li+) constitutes the major barrier to accessing its theoretical capacity of 274 mAh g−1. Although a few high-voltage LCO (H-LCO) materials have been discovered and commercialized, the structural origin of their stability has remained difficult to identify. Here, using a three-dimensional continuous rotation electron diffraction method assisted by auxiliary high-resolution transmission electron microscopy, we investigate the structural differences at the atomistic level between two commercial LCO materials: a normal LCO (N-LCO) and a H-LCO. These powerful tools reveal that the curvature of the cobalt oxide layers occurring near the surface dictates the structural stability of the material at high potentials and, in turn, the electrochemical performances. Backed up by theoretical calculations, this atomistic understanding of the structure–performance relationship for layered LCO materials provides useful guidelines for future design of new cathode materials with superior structural stability at high voltages.