Flexible oxide ceramic films offer prospects for revolutionizing diverse fields such as energy and electronics, but their fabrication methods are typically elaborate and cannot be expanded. Here, we report a scalable strategy to fabricate flexible and robust SiO2 nanofiber films with controllable morphology using a sol-gel electrospinning method followed by low-temperature calcination. When applied to composite polymer electrolytes (CPEs) for solid-state batteries by filling polyethylene oxide into porous ceramic films, SiO2 nanofibers with large surface areas (51 m(2).g(-1)) demonstrate strong Lewis interfacial interactions and isotropic ionic transfer channels that mitigate polymer crystallinity and Li+-concentration polarization, imparting high conductivity (1.3 x 10(-4) S.cm(-1) at 30 degrees C) and structural stability to the electrolytes. As a result, all-solid-state LiFePO4 parallel to Li shows great rate capability and long cycling stability with high discharge capacities of 159 and 132 mA.h.g(-1) at 0.5C under 60 and 45 degrees C, respectively, demonstrating broad commercial prospects for the scale production of efficient solid electrolytes.