Hybrid solid electrolytes by design: architectural pathways toward next-generation solid-state batteries

Conventional solid-state electrolytes often suffer from limited ionic conductivity and poor interfacial compatibility, motivating the development of hybrid solid electrolytes (HSEs) that combine the flexibility of polymers with the stability of ceramics. HSE integrate polymer and ceramic phases provide enhanced mechanical integrity during long-term cycling, improved solid–solid contact at electrode interfaces, and multiple ionic transport pathways that collectively boost ionic conductivity. These features also enable the fabrication of flexible and safe solid-state batteries. This review summarizes the progress in HSE development and the architectural models currently adopted, including single-layer, double-layer, and multilayer configurations. The relationship between polymer–ceramic composition, structural design, and resulting electrochemical properties is discussed, highlighting how architectural optimization governs overall performance. Finally, the review presents a forward-looking perspective on material innovation and structural engineering strategies aimed at accelerating the practical implementation of hybrid solid electrolytes in next-generation solid-state batteries.