Designing Ionic Conductors: The Interplay between Structural Phenomena and Interfaces in Thiophosphate-Based Solid-State Batteries

Elucidating the underlying structural principles that govern ionic transport in thiophosphate solid electrolytes will enable the discovery of novel ionic conductors. Additionally, improving the properties of ionic conductors and exacting control over interfacial reactions and interphase stabilities are critical to the advancement of solid-state batteries. In this perspective, we focus on two major aspects at the foundation of solid-state battery development. First, we address the typical static structural requirements for achieving high ionic conductivities within thiophosphates, which is then extended to how a dynamic lattice and local structural effects can influence ionic transport. Furthermore, we provide an overview of some of the challenges that are currently hindering the progress of solid-state battery research, with particular attention being paid to interfacial instabilities and mechanochemical effects. We hope that this perspective provides a unique outlook on ionic conduction in thiophosphates toward the design of future solid electrolytes and highlights the importance of interfacial chemistry in the optimization of solid-state battery devices.