Ion diffusions driven by dynamic lattice deformations in perovskite solid electrolyte

Abstract

Solid electrolyte (SE) is a crucial component of all-solid-state batteries. Development of SE 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 LixLa(2-x)/3TiO3 perovskite by means of highly efficient machine learning-based molecular dynamics simulations. We revealed a “lattice squeezing effect” where 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 SE. Besides, a new concerted diffusion mechanism with lattice deformation as medium has been uncovered. This study provides a new mechanism demonstrating how lattice dynamics contributes to the ion diffusion, potentially paving the way for developing high-performance SEs.