Novel quasi-solid batteries with In-Situ originated from gel polymer electrolyte

• A novel gel polymer electrolyte (ATGPE) was synthesized in situ with synergistic promotion of fast Li + transport with –CN and −CF 3 functional groups; • The ATGPE with a LiF/Li 3 N-rich SEI layer exhibits high ionic conductivity (3.81 mS cm −1 ) and a large Li + transference number (0.69); • The Li-O 2 cell with the ATGPE delivers long cycle life and high rate performance. Gel polymer electrolytes (GPEs) offer a compelling pathway toward safe, high-performance lithium metal-based batteries. Yet their practical deployment in lithium-oxygen batteries (LOBs) remains limited by insufficient Li + transport, unstable Li interfaces, and poor electrolyte retention under oxygen-rich conditions. Here, we report an in situ-polymerized Acrylonitrile-Trifluoroethyl acrylate Gel Polymer Electrolyte (ATGPE), constructed from AN and TFEA monomers, which forms a flexible, interconnected polymer network enriched with –CN and −CF 3 functionalities. These polar groups strongly coordinate with Li + , reduce the desolvation barrier, and regulate anion mobility, enabling a high ionic conductivity of 3.81 mS cm −1 and an ultrahigh Li + transference number of 0.69. More importantly, the copolymer framework promotes the formation of a robust, LiF/Li 3 N-rich SEI layer, ensuring uniform Li plating/stripping and effectively suppressing dendrite formation and side reactions. Benefiting from its enhanced interfacial stability, flame retardancy, and suppressed electrolyte volatility, ATGPE-based LOBs deliver outstanding long-term durability, achieving 359 stable cycles at 1 A g −1 and exceptional rate capability up to 5 A g −1 , far surpassing conventional liquid electrolyte counterparts. This work provides a mechanistically informed design strategy for constructing multifunctional GPEs and highlights the broad applicability of synergistic –CN/-CF 3 polymer networks for next-generation high-energy–density rechargeable batteries.