The search for new solid-state electrolytes (SSEs) with fast ionic conductivity and high electrochemical stability is one of most challenging issues for developing all-solid-state batteries. Most SSEs have specific ionic transport channels with the crystal structures of perovskite, NASICON, LISICON, and garnet. In this work, we predicted Li-rich layered Li₃NbO₄-type compounds as high-rate and stable SSEs. First-principles calculations show that the predicted Li₃NbO₄ compound has peculiar stacked structures of edge-shared [LiO₅] and [NbO₅] hexahedrons and exhibits higher thermodynamic stability than the experimentally synthesized compound with an octahedral stacked structure at <495 K. Its intralayer Li⁺ conductivity along the hexahedron–octahedron–hexahedron (h-o-h) path has a low energy barrier and low ionic conductivity. We further predicted Li₂Mg_0.5NbO₄ as an SSE with a low ionic migration barrier of 0.33 eV, which is comparable with those of most other oxide SSEs. Therefore, the present study opens a new avenue to design high-performance SSEs in crystal space of layered rocksalt.

中文翻译：

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预测富锂层状氧化物化合物作为高导电性和稳定的固体电解质

寻找具有快速离子电导率和高电化学稳定性的新型固态电解质（SSE）是开发全固态电池最具挑战性的问题之一。大多数 SSE 具有特定的离子传输通道，具有钙钛矿、NASICON、LISICON 和石榴石的晶体结构。在这项工作中，我们预测富锂层状 Li ₃ NbO ₄型化合物是高速率和稳定的 SSE。第一性原理计算表明，预测的Li ₃ NbO ₄化合物具有边缘共享的[LiO ₅ ]和[NbO ₅ ]的特殊堆叠结构] 六面体，比实验合成的具有八面体堆叠结构的化合物在 <495 K 时表现出更高的热力学稳定性。其沿六面体-八面体-六面体 ( h - o - h ) 路径的层内 Li ⁺电导率具有低能垒和低离子电导率。我们进一步预测 Li ₂ Mg _0.5 NbO ₄作为 SSE，具有 0.33 eV 的低离子迁移势垒，与大多数其他氧化物 SSE 相当。因此，本研究为在层状岩盐晶体空间设计高性能 SSE 开辟了一条新途径。