Li ion diffusion behavior of Li3OCl solid-state electrolytes with different defect structures: insights from the deep potential model

Abstract

Li₃OX (X = Cl, Br), a lithium-rich anti-perovskite material developed in recent years, has received tremendous attention due to its high ionic conductivity of >10⁻³ S cm⁻¹ at room temperature. However, the origin of the high ionic conductivity of the material at the atomic level is still not clear. In this work, we investigated the dynamic behavior of the Li₃OCl system with three different defect structures (Li-Frenkel, LiCl-Schottky, and Cl–O anti-site disorder) at seven temperature intervals and calculated its ionic conductivity using the deep potential (DP) model. The results show that the presence of LiCl-Schottky defects is the main reason for the high performance of the Li₃OCl system, and the Li vacancy is the main carrier. The ionic conductivity obtained from the DP model is 0.49 × 10⁻³ S cm⁻¹ at room temperature and it can reach 10⁻² S cm⁻¹ above the melting point, which is in the same order of magnitude as the experimentally reported results. We also explored the effect of different defect concentrations on the ionic conductivity and migration activation energy. This work also demonstrates the feasibility of the DP method for solving the accuracy–efficiency dilemma of ab initio molecular dynamics (AIMD) and classical molecular dynamics simulations.