Recent advances in high-entropy solid electrolytes for all-solid-state lithium batteries

Rechargeable batteries have made important progress as an important means of sustainable development because of the non-renewable nature of fossil fuels has increased the demand for energy. As the “heart” of a rechargeable battery, the electrolyte directly determines the cycling performance of the battery. At present, electrolytes often have problems such as limited operating temperature and unsatisfactory ionic conductivity at room temperature. The introduction of electrode materials into the high-entropy strategy has improved the cycling performance of batteries, so the corresponding high-entropy electrolytes (HEEs) have high research value due to their disordered structure. However, there is still a lack of clear concepts and guidelines for efficient synthesis of HEEs, and the mechanism of corresponding performance improvement is unclear, which restricts the further development of HEEs. Herein, we summarize the application and working mechanism of HEEs in all-solid-state batteries. First, the development history and related definition of HEES are introduced. Then we discuss the application of HEES in existing solid electrolyte systems and its corresponding action mechanism, focusing on its improvement in ionic conductivity and interface wettability. Then, the current common synthesis methods and advanced characterization techniques of HEEs are introduced. Finally, the currently unsolved problems of HEEs and the corresponding potential development pathway are proposed. This review provides new ideas and insights for the study of high-performance solid-state electrolytes for commercial applications.