Rational design of sulfide solid electrolytes for solid-state batteries

Sulfide solid electrolytes are widely regarded as key enablers of high-energy all-solid-state batteries owing to their high Li-ion conductivity and ability to form intimate solid–solid contact. However, their practical deployment remains hindered by complex interfacial degradation, where electrochemical reactions, chemo-mechanical damage, transport limitations, and processing-induced defects are strongly coupled. Although prior reviews have summarized specific sulfide electrolytes or individual interfacial phenomena, a unified mechanistic framework linking degradation pathways across different battery chemistries is still lacking. In this Perspective, we discuss how interfacial degradation manifests in representative systems based on Li-metal and Si anodes, as well as sulfur and layered-oxide cathodes. We further assess strategies developed to mitigate these failure modes, including electrolyte design, interface engineering, electrode architecture optimization, and manufacturing innovations. By considering these challenges as interconnected rather than isolated, we highlight common physicochemical principles governing interfacial instability in sulfide-based all-solid-state batteries. Finally, we outline emerging opportunities enabled by advanced characterization, multiscale modeling, scalable processing, and artificial-intelligence-assisted materials discovery. This Perspective aims to provide a mechanistic basis for developing durable sulfide-based all-solid-state batteries and inspires more rational strategies for future electrolyte and interface design.