Halide solid electrolytes in all-solid-state batteries: Ion transport kinetics, failure mechanisms and improvement strategies

Halide solid electrolytes (SEs) have emerged as a prominent area of research interest due to their exceptional properties. Currently, there is growing interest in halide SEs, driven by optimized structural frameworks, advanced synthesis methods, and enhanced physico-mechanical deformability rooted in halogen chemistry . In this paper, we devote to describing the mechanism of ion transport kinetics in halide SEs, while also presenting an overview of the current research status and future development prospects in halide-based all-solid-state batteries (ASSBs). The application of modeling and theoretical calculations has provided a significant impetus to the field. In addition, it presents a summary of the potential sources of ion transport failure in halide SEs and the electrode|SE interface, and proposes effective strategies to address these issues. Ultimately, this paper provides a forward-looking perspective on prospective avenues of research in halide SEs, drawing insights from investigations into cycle stability and rapid ion conduction in this field. The review promotes our understanding on the dynamics of fast ion conduction in halide SEs, which offers valuable insights to guide the development of innovative halide SEs. Given the complex relation of structures, ionic conduction, preparation, and failure mechanisms of halide solid electrolytes in batteries, its in-depth understanding is far from complete and highly challenging. This review presents an overview of the current state of ionic conduction dynamics, the relationship between preparation condition and ionic conductivity of halide SEs. Other factors affecting the ion conduction and failure mechanisms, and improvement strategies for halide solid electrolytes and halide-based batteries. • This paper reviews the ion transport dynamics of halide solid electrolytes. • The preparation conditions and other factors affecting halide SEs are reviewed. • The failure mechanism of halide solid electrolytes in batteries are summarized. • The promising strategies to improve the halide SEs are summarized. • Perspectives are given on how to design high-performance halide SEs materials.