Understanding Oxygen-Ion Migration in Hexagonal Perovskites Through Autonomous Workflows and Density Functional Theory

Low-temperature oxygen-ion conductors are playing a key role in the transition to more sustainable energy storage technologies. Herein, by leveraging high-throughput Density Functional Theory calculations and the Nudged Elastic Band method through autonomous workflows, we systematically analyze a chemical space comprising 5,400 hexagonal perovskite structures and evaluate their potential as oxygen ion conductors using various computational descriptors. Our findings reveal 29 promising candidate compositions, many of which remain experimentally unexplored. We further investigated the mechanisms of oxygen-ion migration, classifying them into two distinct types: ion-hopping and cooperative migration. Notably, the cooperative mechanism, characterized by the rotation of flexible lattice units, consistently yields lower activation barriers and enhanced ion mobility. These insights not only expand the pool of candidate materials but also deepen our understanding of migration mechanisms, paving the way for experimental validation and the development of next-generation energy storage devices.