Ceramic–Polymer Composite Solid‐State Electrolytes for Solid‐State Lithium Metal Batteries: Mechanism, Strategy, and Prospect

The low energy density and safety problems of lithium-ion batteries based on liquid electrolyte have set off a new wave of high specific capacity and high safety battery design to meet the need of future market. Solid-state lithium metal battery has been widely concerned for its high energy density, safety, and electrochemical stability. Especially, polymer-based solid-state electrolytes (polymer SSEs) have attracted much attention due to the good interfacial contact, flexible mechanical properties, and physical/chemical stability. However, the deficiencies of low ionic conductivity and weak mechanical strength limit the further development of polymer SSEs. Here, hybrid ceramic-polymer composite solid-state electrolytes (CSSEs), specifically consisted of polymers and inorganic ceramic active fillers, can achieve good interfacial contact, high ionic conductivity, excellent mechanical properties, and Li dendrite growth inhibition. Based on the intrinsic characteristics of polymers, this review expounds the strategies to improve the performance of ceramic-polymer CSSEs. Especially, the screening and modification strategies of polymer and ceramic active fillers in recent years, including structural design, surface modification, and interface engineering, are reviewed. Finally, the core ideas of the existing designs, and proposed feasible solutions, aiming at providing future development and industrialization of ceramic-polymer CSSEs are summarized.