Oxygen Vacancy-Induced Directional Ordering of Li-Ion Pathways for Enhanced Ion-Conducting Solid Electrolytes
Hyeon‐Ah Ju, Eun‐Byeol Park, Jaejin Hwang, Young‐Hoon Kim, Young‐Hoon Kim, Min‐Hyoung Jung, Minji Yang, Seon Je Kim, Jaehan Lee, Jaehan Lee, Ivana K. Kim, Yoo-Shin Kim, Yoo-Shin Kim, Songhun Yoon, Jae Hyuck Jang, Hu Young Jeong, Jae-Kwang Lee, Jae-Kwang Lee, Jae‐Hyun Shim, Young-Min Kim, Young-Min Kim
Abstract
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.