Leveraging local structural disorder for enhanced ion transport

Fast-ion conductors, also known as solid electrolytes, are a critical component to the development of high-performance all-solid-state batteries. Conventional lithium solid electrolytes are limited by low ionic conductivity due to high energy barriers for Li+ transport. Recent advancements in promoting fast-ion transport have been achieved through weakening the interaction of Li-ions with their coordinated anions via the introduction of local disorder on the atomic-, nano-, and meso-scale. Difficulty in the coherent characterization of local-entropy-enhanced ion conductors arises from the modified structural framework, which consists of highly disordered local structures within an ordered long-range network. This review outlines an experimental approach to systematically probe the relation between material structure, ion dynamics, and ion conduction, guided by solid-state NMR. Examples of our work on local-entropy-enhanced ion conductors are highlighted to encourage future studies to further optimize the properties of solid electrolytes for a wide range of technological applications.