High-entropy strategies for designing advanced solid-state electrolytes: a comprehensive review

All-solid-state lithium metal batteries (ASSLMBs) have garnered significant attention due to their potential for high energy densities and enhanced safety. Solid-state electrolytes (SSEs) are critical components in ASSLMBs, with their ionic conductivity and interfacial compatibility directly influencing battery performance. However, current SSEs often exhibit lower ionic conductivity and higher interfacial resistance compared to liquid electrolytes. To address these challenges, high-entropy strategies have emerged as promising approaches to enhance structural disorder and stability in SSEs. This review provides a comprehensive overview of high-entropy strategies applied to SSEs, including inorganic, polymer, and composite SSEs. We elucidate the fundamental concepts of high entropy and its four core effects (high-entropy effect, lattice distortion effect, sluggish-diffusion effect, and cocktail effect) and discuss their impact on the performance of SSEs. Recent progress in applying high-entropy strategies to different types of SSEs is summarized, highlighting structural optimization and performance enhancement. Challenges and future directions for the development of high-entropy SSEs are also presented. The insights provided in this review aim to guide the rational design of high-performance SSEs for next-generation energy storage systems.