Materials-Property Classification of Interlayers for Stabilizing Lithium Metal Interfaces in Sulfide-Based All-Solid-State Batteries

초록

Sulfide-based all-solid-state lithium metal batteries (ASSLMBs) promise high energy density by using lithium metal anodes, but their practical implementation is limited by severe interfacial instability. At the lithium metal/sulfide electrolyte interface, coupled chemical, electrochemical, and mechanical degradation accelerates impedance growth and cell failure. Interlayer strategies are promising for stabilizing sulfide-based all-solid-state batteries because they can mitigate interfacial degradation, improve contact stability, and regulate ion/electron transport at critical electrode-electrolyte interfaces. However, their mechanisms have largely been interpreted based on phenomenological observations and empirical performance improvements, rather than through intrinsic material property-mechanism relationships, highlighting the need for a material property-driven design framework. Here, we categorize interlayer strategies into metal, polymer, ceramic, and composite systems and reinterpret their functions from an electro-chemo-mechanical perspective. We discuss how stiffness, ductility, fracture toughness, electronic conductivity, electrochemical stability, chemical stability, lithiophilicity, and Li-ion transport govern interfacial behavior during assembly, plating, stripping, and long-term cycling. By correlating representative interlayer systems with their electro-chemo-mechanical properties, this perspective clarifies the relationship between material characteristics and interfacial stabilization behavior in sulfide-based ASSLMBs. This property-driven framework is expected to provide practical criteria for screening unexplored interlayer materials and guiding the rational design of stable lithium metal/sulfide electrolyte interfaces.

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