Constructing Ceramic–Polymer Composite Electrolytes via In Situ Polymerization Strategy for High Safety Solid-State Lithium Metal Batteries

Solid-state electrolytes have attracted considerable attention for application in next-generation solid-state lithium metal batteries (SLMBs). However, the intrinsic single-component solid-state electrolytes have seriously hindered the development of SLMBs by conflicting requirements for ionic conductivity, interfacial compatibility, mechanical robustness, and electrochemical stability. Herein, we report a ceramic–polymer (LATP@PP@PDOL) composite electrolyte via an in situ polymerization strategy, where a ceramic-coated (LATP@PP) membrane was used as a supporting base. The LATP@PP scaffold provided structural integrity and dendrite-suppressing rigidity, while the in-situ-formed poly(1,3-dioxolane) uniformly infiltrated pore networks and conformed to electrode–electrolyte interfaces, thereby eliminating interfacial voids and enhancing Li + transport kinetics. This dual-phase architecture ensured dimensional stability, improved interfacial contact, and synergistic ion-conduction pathways. Thus, the designed ceramic–polymer composite electrolyte achieved a room-temperature ionic conductivity of 0.51 mS cm –1, a lithium-ion transference number of 0.82, and an electrochemical stability window of 4.75 V. When integrated into a Li||LiFePO 4 solid-state battery, it delivered exceptional capacity retention of 97.2% after 200 cycles at 0.2C. Even at 2C, it could also provide the high reversible capacity of 134 mAh g –1 after 400 cycles with 82% capacity retention. These results verified that the above ceramic–polymer composite electrolyte combining ceramic components with in situ polymerization of poly(1,3-dioxolane) can effectively and synergistically enhance the comprehensive performance of solid-state electrolytes, providing an idea for the development of composite electrolytes and promoting the application of ceramic-coated membranes from liquid batteries to safer SLMBs.