Solid electrolytes are generating considerable interest for all-solid-state Li-ion batteries to address safety and performance issues. Grain boundaries have a significant influence on solid electrolytes and are key hurdles that must be overcome for their successful application. However, grain boundary effects on ionic transport are not fully understood, especially at the atomic scale. The Li-rich anti-perovskite Li3OCl is a promising solid electrolyte, although there is debate concerning the precise Li-ion migration barriers and conductivity. Using Li3OCl as a model polycrystalline electrolyte, we apply large-scale molecular dynamics simulations to analyze the ionic transport at stable grain boundaries. Our results predict high concentrations of grain boundaries and clearly show that Li-ion conductivity is severely hindered through the grain boundaries. The activation energies for Li-ion conduction traversing the grain boundaries are consistently higher than that of the bulk crystal, confirming the high grain boundary resistance in this material. Using our results, we propose a polycrystalline model to quantify the impact of grain boundaries on conductivity as a function of grain size. Such insights provide valuable fundamental understanding of the role of grain boundaries and how tailoring the microstructure can lead to the optimization of new high-performance solid electrolytes.

中文翻译：

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晶界对全固态电池固体电解质中锂离子传导的原子尺度影响

固体电解质对解决安全和性能问题的全固态锂离子电池产生了极大的兴趣。晶界对固体电解质具有重大影响，并且是其成功应用必须克服的关键障碍。然而，尚未完全了解晶界对离子传输的影响，尤其是在原子尺度上。富锂反钙钛矿 Li3OCl 是一种很有前途的固体电解质，尽管关于精确的锂离子迁移势垒和电导率存在争议。使用 Li3OCl 作为模型多晶电解质，我们应用大规模分子动力学模拟来分析稳定晶界处的离子传输。我们的结果预测了高浓度的晶界，并清楚地表明锂离子电导率通过晶界受到严重阻碍。跨越晶界的锂离子传导的活化能始终高于块状晶体的活化能，证实了该材料的高晶界电阻。使用我们的结果，我们提出了一个多晶模型来量化晶界对作为晶粒尺寸函数的电导率的影响。这些见解为了解晶界的作用以及调整微观结构如何优化新型高性能固体电解质提供了宝贵的基础知识。证实了这种材料的高晶界电阻。使用我们的结果，我们提出了一个多晶模型来量化晶界对作为晶粒尺寸函数的电导率的影响。这些见解为了解晶界的作用以及调整微观结构如何优化新型高性能固体电解质提供了宝贵的基础知识。证实了这种材料的高晶界电阻。使用我们的结果，我们提出了一个多晶模型来量化晶界对作为晶粒尺寸函数的电导率的影响。这些见解为了解晶界的作用以及调整微观结构如何优化新型高性能固体电解质提供了宝贵的基础知识。