Dislocation and oxygen-release driven delithiation in Li2MnO3
Dislocation and oxygen-release driven delithiation in Li2MnO3
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DOI：
10.1038/s41467-020-18285-z
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发表时间：
2020-09-08
影响因子：
16.6
通讯作者：
Ikuhara, Yuichi
中科院分区：
文献类型：
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作者：
Nakayama, Kei;Ishikawa, Ryo;Ikuhara, Yuichi
锂过量层状正极材料如Li 2 MnO 3由于其高能量密度而引起了广泛关注。有人提出，释氧和阳离子混合可能是由脱锂引起的。然而，目前尚不清楚脱锂区域如何增长。在这里，通过使用原子分辨率扫描透射电子显微镜结合电子能量损失谱，我们直接观察原始和脱锂区域之间的界面处的原子结构在部分脱锂的Li 2 MnO 3单晶。我们阐明脱锂区域具有大量的不可逆缺陷，如氧释放和Mn/Li阳离子混合。在界面处，形成部分阳离子无序结构，其中Mn迁移仅发生在特定的Mn/Li层中。此外，在界面处形成了大量位错，以补偿原始区和脱锂区之间的晶格失配。所观察到的氧释放和位错可以控制锂锰氧化物的脱锂区域的生长和性能下降。
Lithium-excess layered cathode materials such as Li2MnO3 have attracted much attention owing to their high energy densities. It has been proposed that oxygen-release and cation-mixing might be induced by delithiation. However, it is still unclear as to how the delithiated-region grows. Here, by using atomic-resolution scanning transmission electron microscopy combined with electron energy-loss spectroscopy, we directly observe the atomic structures at the interface between pristine and delithiated regions in the partially delithiated Li2MnO3 single crystal. We elucidate that the delithiated regions have extensive amounts of irreversible defects such as oxygen-release and Mn/Li cation-mixing. At the interface, a partially cation disordered structure is formed, where Mn migration occurred only in the specific Mn/Li layers. Besides, a number of dislocations are formed at the interface to compensate the lattice mismatch between the pristine and delithiated regions. The observed oxygen-release and dislocations could govern the growth of delithiated-regions and performance degradation in Li2MnO3.