Molecular Dynamics Studies on the Lithium Ion Conduction Behaviors Depending on Tilted Grain Boundaries with Various Symmetries in Garnet-Type Li7La3Zr2O12
Molecular Dynamics Studies on the Lithium Ion Conduction Behaviors Depending on Tilted Grain Boundaries with Various Symmetries in Garnet-Type Li7La3Zr2O12
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DOI：
10.1021/acs.jpcc.8b06275
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发表时间：
2018-08
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通讯作者：
Hiromasa Shiiba;N. Zettsu;M. Yamashita;H. Onodera;R. Jalem;M. Nakayama;Katsuya Teshima
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文献类型：
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作者：
Hiromasa Shiiba;N. Zettsu;M. Yamashita;H. Onodera;R. Jalem;M. Nakayama;Katsuya Teshima
晶界结构是影响材料宏观性能的重要参数，然而，用现代分析方法评价晶界结构仍然是一项极具挑战性的任务。在这项工作中，我们用各种分子动力学方法结合最新发展的分析技术研究了具有石榴石骨架的立方Li7La3Zr2O12(LLZO)(这是全固态电池中最有希望的固体电解液候选材料)GBs上Li+的电导退化。研究发现，无论GB对称性如何，Li离子的跨界扩散一般都比它们在体相中的扩散慢，但这一效应强烈依赖于GB层中Li缺位的浓度(捕获Li空位)。此外，结合GB区的致密性和密度是影响LLZO多晶薄膜整体Li+导电性的关键参数。
Grain boundary (GB) structure is a critical parameter that significantly affects the macroscopic properties of materials; however, the evaluation of GB characteristics by modern analytical methods remains an extremely challenging task. In this work, Li+ conductivity degradation at the GBs of cubic Li7La3Zr2O12 (LLZO) with a garnet framework (which represents the most promising candidate material for solid electrolytes utilized in all-solid-state batteries) has been investigated by various molecular dynamics approaches combined with newly developed analytical techniques. It was found that the transboundary diffusion of Li ions was generally slower than their diffusion in the bulk regardless of the GB symmetry; however, this effect strongly depended on the concentration of Li-deficient sites (trapping Li vacancies) in the GB layer. Furthermore, the compactness and density of the combined GB regions represent the key parameters affecting the overall Li+ conductivity of polycrystalline LLZO films.