Network‐Driven Ion Transport in Robust In Situ Polymerized Electrolyte‐Integrated Cathodes for Long‐Life Structural Batteries in Intelligent Sensing Platforms

Abstract The limited cycle life of solid‐state lithium‐ion batteries is largely attributed to the low ionic conductivity and poor mechanical strength of solid electrolytes, as well as unstable electrode/electrolyte interfaces. Herein, a solid‐state electrolyte synthesized via in situ polymerization of bisphenol A ethoxylate dimethacrylate (E2BADMA) and poly(ethylene oxide) diacrylate (PEGDA) in LiTFSI–carbonate‐based electrolytes is reported, achieving high ionic conductivity and mechanical robustness. By combining density functional theory (DFT) simulations and experimental validation, a previously unidentified network‐enhanced transport mechanism is uncovered, whereby the poly(E2BADMA) chains not only enhance mechanical integrity but also introduce abundant active sites for Li + transport. Leveraging these properties, an integrated solid electrolyte/cathode architecture with excellent electrochemical performance and high stiffness is constructed. When incorporated into full cells, the electrolyte facilitates the formation of robust electrode/electrolyte interfaces, significantly improving their interfacial stability and enabling long‐term cycling. The resulting solid‐state lithium‐ion batteries display stable performance over 300 cycles with negligible capacity fading. Moreover, the solid electrolyte enables the development of structural batteries which retain ≈100 mAh g −1 after 120 cycles. When deployed as load‐bearing elements in a conceptual electric vehicle frame, these structural batteries reliably power movable platforms and multiple sensors, showcasing their potential in intelligent, multifunctional, and energy‐efficient transport systems.