Optimization strategies for key interfaces of LLZO-based solid-state lithium metal batteries

Abstract

Solid-state lithium metal batteries (SSLMBs) are believed to be next-generation energy storage systems owing to their superior safety performance and higher energy density compared with state-of-the-art lithium-ion batteries. Solid-state electrolytes (SSEs), as the most critical component of solid-state batteries (SSBs), determine the performance of the batteries to a large extent. Among different types of SSEs, the garnet-type Li₇La₃Zr₂O₁₂ (LLZO) has an exceptionally high ionic conductivity (10⁻³ to 10⁻⁴ S cm⁻¹) and good chemical stability against lithium metal, providing a fantastic possibility for use in SSLMBs. However, developing usable, accessible LLZO-based SSLMBs is still a difficult task owing to the interfacial issues. This review concentrates on the key interfaces of LLZO-based SSLMBs, including lithium metal/LLZO interfaces, LLZO/cathode interfaces, and internal interfaces of LLZO-based SSEs. The main challenges and corresponding strategies for interface optimization are thoroughly covered. Comprehensive research models and advanced characterization tools deployed and developed to study the aforementioned issues are also outlined. Additionally, effective solutions from the perspective of engineering applications are highlighted. Finally, perspectives for future research are provided to guide the development of LLZO-based SSLMBs.