Defects in perovskite oxide solid electrolytes (SEs) impact Li-ion conductivity. However, the role of oxygen vacancies (V_o) in transport behavior has been less explored. Herein, our study elucidates the microscopic origin of the role of V_o in enhancing the total ionic conductivity of a prototype lithium lanthanum titanate while maintaining its insulating properties. Scanning transmission electron microscopy and theoretical calculations reveal that the presence of V_o significantly lowers the activation energy of Li-ion migration. The V_o is revealed to be preferentially aligned parallel to c-planes and causes modulated lattice expansion in an alternating manner, resulting in easy directional Li-ion transport. The effect of V_o-assisted Li-ion transport is optimized through the hierarchical rearrangement of structural features at multiple length scales close to the direction of the V_o arrays. Our results offer novel insights into the microscopic origins of superior ion conductivity facilitated by V_o, contributing to the design of high-performance SEs.

中文翻译：

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氧空位诱导的增强型离子导电固体电解质的锂离子通路定向有序


钙钛矿氧化物固体电解质 （SE） 中的缺陷会影响锂离子电导率。然而，氧空位 （V_o） 在运输行为中的作用尚未得到充分探索。在此，我们的研究阐明了 V_o 在增强原型钛酸锂镧酸锂的总离子电导率同时保持其绝缘性能中的作用的微观起源。扫描透射电子显微镜和理论计算表明，V_o 的存在显着降低了锂离子迁移的活化能。结果表明，V_o 优先平行于 c 平面排列，并以交替方式引起调制晶格膨胀，从而轻松实现锂离子定向传输。通过在靠近 V_o 阵列方向的多个长度尺度上对结构特征进行分层重排，优化了 V_o 辅助锂离子传输的效果。我们的结果为 V_o 促进的卓越离子电导率的微观起源提供了新的见解，有助于高性能 SE 的设计。