In Situ Fabrication and Synergistic Enhancement of PDOL-Based Composite Quasi-solid Electrolyte by Organic/Inorganic Additives for Practical Lithium Batteries

Low ionic conductivity, inadequate interfacial stability, and complex electrolyte-membrane fabrication procedures have long stood as the core bottlenecks restricting the advancement of polymer-based solid-state batteries. In this study, we develop an in situ thermally initiated polymerization strategy to fabricate PDOL/PMMA composite matrices, which are further synergistically tailored by incorporating Li 7 La 3 Zr 2 O 12 (LLZO) ceramic filler and fluoroethylene carbonate (FEC). This design yields a composite quasi-solid electrolyte capable of concurrently optimizing ionic conduction and interfacial stability. Within the multicomponent system: the flexible PDOL domain establishes interconnected continuous pathways for lithium-ion migration, the rigid PMMA component affords robust mechanical reinforcement, the LLZO inorganic filler may regulate local ion coordination and anion migration through polymer/ceramic interfacial interactions and accessible surface sites, thereby contributing to the elevated lithium-ion transference number and strengthens the electrolyte’s capability to suppress lithium dendrite propagation, meanwhile, FEC undergoes preferential reductive decomposition at the surface of the lithium metal anode, generating a compact SEI layer rich in lithium fluoride (LiF) that effectively inhibits parasitic interfacial side reactions. The results demonstrate that the composite quasi-solid electrolyte achieves a room-temperature ionic conductivity of 4.42×10 -4 S cm -1 , a Li + transference number of 0.82, and an electrochemical window of 4.7 V. Lithium symmetric cells can stably cycle for over 1600 h at 0.1 mA cm -2 . This work confirms the critical role of synergistic optimization between inorganic fillers and polymer matrices in enhancing the overall performance of composite electrolytes, and provides a green and practical fabrication strategy for the engineering of solid-state lithium batteries.