Research on electrolyte structure and interface design for solid state Lithium-Sulfur batteries: Challenges, strategies and prospects

Solid-state lithium-sulfur batteries (SSLSBs) incorporating solid-state electrolytes (SSEs) represent a promising solution to the energy density constraints and safety concerns associated with conventional lithium metal batteries. However, the practical implementation of single-phase SSEs remains limited by suboptimal performance metrics. Composite solid electrolytes (CSEs), which synergistically combine the advantages of inorganic solid electrolytes (ISEs) and solid polymer electrolytes (SPEs), have emerged as a viable alternative, offering superior ionic conductivity, lower interfacial resistance, and enhanced electrode stability in SSLSBs. This review systematically explores the development of solid electrolytes, analyzing the strengths and weaknesses of ISEs, SPEs, and various CSEs. Key strategies to address persistent challenges, including low ionic conductivity, limited electrochemical stability, and high interfacial resistance, are also examined. Particular attention is paid to the impact of electrolyte-electrode interface modifications, specifically at the cathode-electrolyte and anode- electrolyte interfaces, on the overall battery performance. Finally, the review highlights critical challenges and outlines future directions for the practical adoption of composite electrolytes in next-generation energy storage systems.