Achieving high-energy and high-safety lithium metal batteries with high-voltage-stable solid electrolytes

In the pursuit of next-generation energy storage systems, solid-state lithium metal batteries (SSLMBs) that can match both high-voltage cathodes and lithium metal anodes have attracted considerable attention in both industry and academia due to their high-energy density, enhanced safety, and cycle-life benefits. However, SSLMBs suffer from severe degradation of solid electrolytes (SEs) along with the continuously increasing cutoff voltage. Consequently, designing a compatible SE is crucial for high-voltage SSLMBs. In this review, the recent developments of high-voltage SSLMBs in the field of SEs are summarized, including their fundamental understanding, interfacial degradation mechanisms, and application prospects. Moreover, we specifically highlight the design principles needed to achieve intrinsic and extrinsic stability for SEs under high voltage. Finally, a summary of the existing challenges and perspectives on the high-voltage-stable SEs and SSLMBs are also discussed with the aim of guiding the development of state-of-the-art SEs for future high-energy and high-safety SSLMBs.