Ion diffusion driven by dynamic lattice deformations in perovskite solid electrolytes

Abstract

The solid electrolyte (SE) is a crucial component of all-solid-state batteries. Development of SEs with high ion conductivity needs an in-depth understanding of ion diffusion mechanisms. Recently, the influence of lattice dynamics on ion diffusion in Li-ion conductors has attracted widespread attention. In this study, we intensively investigated the ion diffusion mechanism in Li_xLa_(2−x)/3TiO₃ perovskite by means of highly efficient machine learning-based molecular dynamics simulations. We revealed that dynamic lattice deformation can trigger ion hopping, while local distortions of TiO₆ octahedra adversely affect long-range ion diffusion. Based on the acquired design principles, a new model was constructed, which exhibits an encouragingly high ion conductivity for perovskite SEs. Besides, a new concerted diffusion mechanism with lattice deformation as the medium has been uncovered. This study provides a new mechanism demonstrating how lattice dynamics contributes to ion diffusion, potentially paving the way for developing high-performance SEs.