Polyurethane Solid Electrolyte Interface Mechanical-Electrochemical Coupling Characteristics Enhanced by SiO ₂ Aerogel Cross-Linking Reaction for Fast Li ⁺ Interface Dynamics

Lithium metal batteries are the most promising representative for achieving high-energy-density battery systems. However, interface instability and lithium dendrite growth are important challenges facing large-scale applications. Polymer solid electrolytes have both the rigidity to suppress lithium dendrite growth and the toughness to accommodate interface fluctuations, making them a necessary path for the development of solid-state lithium metal batteries. Solid-state lithium metal batteries still have poor solid contact interfaces, which are affected by multiple effects of interface mechanics and electrochemistry. In this work, polyurethane with excellent mechanical properties was used as the substrate, and the cross-linking reaction of SiO₂ aerogel was used to bridge polyurethane and polymethacrylate polymers, to investigate the influence mechanism of the mechanical-electrochemical characteristics of the interface of a solid electrolyte film on the Li⁺ interface dynamics. Through the synergistic effect of the fluorinated polar groups and silicon oxygen skeleton in the solid electrolyte film, the synergistic effects of increasing Young's modulus, enhancing mechanical stiffness, and improving electrochemical stability and interface compatibility have been achieved, thus establishing the mechanism of the mechanical-electrochemical coupling characteristics of the solid electrolyte film on interface dynamics, providing a perspective for the practical application of polymer solid-state batteries.