Grystalline Grain Interior Configuration affects lithium migration kinetics in li-rich layered oxides
Grystalline Grain Interior Configuration affects lithium migration kinetics in li-rich layered oxides
复制标题
晶粒内部结构影响富锂层状氧化物中的锂迁移动力学
DOI：
10.1021/acs.nanolett.5b03933
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发表时间：
2016
期刊：
影响因子：
10.8
通讯作者：
Yuichi Ikuhara
中科院分区：
文献类型：
--
作者：
Haijun Yu;Yeong-Gi So;Akihide Kuwabara;Eita Tochigi;Naoya Shibata;Tetsuichi Kudo;Haoshen Zhou;Yuichi Ikuhara
锂离子电池的电极动力学受电极材料的晶粒尺寸、晶体取向和表面结构的影响，对电动汽车电池的应用具有重要意义。然而，晶粒内部结构和元素偏析的动力学影响尚不清楚，特别是对于晶体结构复杂且电化学现象不明确的富锂层状氧化物。在这项工作中，利用一种新的氩离子切片技术，对原始li1.2 mn0.567 ni0.167 co0.067 o2粉末的截面薄透射电镜样品进行了“解剖”。利用先进的显微技术，清晰地揭示了单晶粒、多个单晶样畴和镍分离畴的内部结构；此外，在每个畴中都存在一个随机分布的原子分辨率Li2MnO3-like和一个互生的LiTMO2（TM =过渡金属）“孪畴”。基于li2mno3类li2mno3晶体畴边界模型的进一步理论计算表明，具有畴边界的li2mno3类li2mno3结构中Li+的迁移缓慢，特别是当镍在畴边界中偏析时。我们的工作揭示了晶体颗粒内部的复杂结构，并为我们对几种锂离子电池化合物的电化学性能的理解提供了概念上的进步。
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 Li1.2Mn0.567Ni0.167Co0.067O2powders 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.