It is widely accepted that grain boundary (GB) in polycrystalline solid-state electrolytes (SSEs) can substantially reduce ionic conduction, which is regarded as the most essential property for SSEs. However, the physical origin of the GB-induced retardation effects remains unanswered. In this study, molecular dynamics simulations and first-principle calculations were combined to reveal the role of GBs in ionic conduction via the evaluation of the thermodynamic–kinetic interaction between GBs and vacancy in cubic Na₃PS₄. Our results suggest that the reduced ionic conduction in GBs is attributed to the segregation of Na vacancy in the GB core. The GB-blocking effects strongly depend on both vacancy segregation energy and the number of segregation sites in the GB core, which are determined by the GB structure. This study will shed new light on the future design of polycrystalline SSEs with a high ionic conductivity via grain boundary engineering.

中文翻译：

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晶界在多晶固态电解质离子电导率中作用的原子学研究

广泛接受的是，多晶固态电解质（SSEs）中的晶界（GB）可以大大减少离子传导，这被认为是SSE的最重要特性。然而，GB诱导的延迟作用的物理起源仍未得到解答。在这项研究中，结合分子动力学模拟和第一性原理计算，通过评估GBs与立方Na ₃ PS _4中空位之间的热动力学相互作用，揭示了GBs在离子传导中的作用。。我们的结果表明，GBs中离子传导的减少归因于GB核中Na空位的分离。GB的阻断作用强烈取决于GB核中的空位离析能和离析位点的数量，这由GB结构决定。这项研究将为未来通过晶界工程设计具有高离子电导率的多晶SSE提供新的思路。