Research progress in interfacial engineering of anodes for sulfide-based solid-state lithium metal batteries

As global energy demand continues to rise, there is an urgent need for sustainable and high-performance energy storage solutions. All-solid-state lithium metal batteries (ASSLMBs) have attracted significant attention due to their high energy density and improved safety compared to conventional liquid-based batteries. By replacing flammable liquid electrolytes with solid alternatives, ASSLMBs address critical safety concerns such as thermal runaway, combustion, and electrolyte leakage, making them strong candidates for next-generation energy storage systems. Among the core components of ASSLMBs, the solid electrolyte plays a crucial role in ensuring ionic conductivity and overall battery performance. Solid electrolytes are generally classified into three types: oxide-based, sulfide-based (SSEs), and polymer-based. Of these, sulfide-based electrolytes have emerged as particularly promising due to their high ionic conductivity and mechanical flexibility, which are considered key attributes for achieving high energy density and long cycling life. Despite their advantages, SSEs face serious interfacial challenges when paired with lithium metal anodes. These include severe side reactions, lithium dendrite formation, and poor interfacial contact, all of which hinder practical application and large-scale deployment. To overcome these obstacles, extensive research has focused on enhancing the stability of the lithium/SSE interface through various strategies. These include constructing protective interlayers, designing composite anodes to suppress dendrite growth, and tuning the chemical and structural properties of SSEs for better compatibility with lithium metal. Although notable progress has been made, fully resolving interfacial issues requires a deeper understanding of the fundamental failure mechanisms, which include electronic, chemical, electrochemical, and electro-chemo-mechanical breakdowns.This review provides a comprehensive and systematic analysis of the interfacial instability challenges between sulfide-based solid electrolytes and lithium metal anodes. It elucidates fundamental failure mechanisms and highlights recent advances in interfacial engineering, such as the development of artificial solid electrolyte interphases (SEI), the use of lithium alloy anodes, and the design of chemically and mechanically optimized SSEs. The role of theoretical modeling is also emphasized as a vital tool for uncovering the dynamic evolution of the interface and guiding material design. Future research directions are proposed, with an emphasis on in-depth multiscale investigations into interfacial failures, the development of advanced in situ characterization techniques, and the integration of artificial intelligence in material discovery. Additionally, the exploration of adaptive interfacial coatings holds promise for significantly enhancing battery stability and safety. In conclusion, this review underscores the critical significance of resolving the interfacial instability in sulfide-based ASSLMBs as it is key to unlocking their full potential. This review sheds light on recent developments of the sulfide-based ASSLMBs and provides a comprehensive understanding of the progress made in overcoming these challenges. Thus, this comprehension offers valuable insights and practical means for advancing ASSLMBs technology toward the adoption of safer, more efficient energy storage technologies.