Crystalline Grain Interior Configuration Affects Lithium Migration Kinetics in Li-Rich Layered Oxide

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• 作者：Haijun Yu ; Yeong-Gi So ; Akihide Kuwabara ; Eita Tochigi ; Naoya Shibata ; Tetsuichi Kudo ; Haoshen Zhou ; Yuichi Ikuhara
• 刊名：Nano Letters
• 出版年：2016
• 出版时间：May 11, 2016
• 年：2016
• 卷：16
• 期：5
• 页码：2907-2915
• 全文大小：809K
• 年卷期：0
• ISSN：1530-6992

文摘

The electrode kinetics of Li-ion batteries, which are important for battery utilization in electric vehicles, are affected by the grain size, crystal orientation, and surface structure of electrode materials. However, the kinetic influences of the grain interior structure and element segregation are poorly understood, especially for Li-rich layered oxides with complex crystalline structures and unclear electrochemical phenomena. In this work, cross-sectional thin transmission electron microscopy specimens are “anatomized” from pristine Li_1.2Mn_0.567Ni_0.167Co_0.067O₂ powders using a new argon ion slicer technique. Utilizing advanced microscopy techniques, the interior configuration of a single grain, multiple monocrystal-like domains, and nickel-segregated domain boundaries are clearly revealed; furthermore, a randomly distributed atomic-resolution Li₂MnO₃-like with an intergrown LiTMO₂ (TM = transitional metals) “twin domain” is demonstrated to exist in each domain. Further theoretical calculations based on the Li₂MnO₃-like crystal domain boundary model reveal that Li⁺ migration in the Li₂MnO₃-like structure with domain boundaries is sluggish, especially when the nickel is segregated in domain boundaries. Our work uncovers the complex configuration of the crystalline grain interior and provides a conceptual advance in our understanding of the electrochemical performance of several compounds for Li-ion batteries.