Composite solid electrolyte with 3D SiO₂ network and continuous Li⁺ transport pathways for highly stable quasi-solid-state lithium-metal batter

Structure design plays a critical role in enabling composite solid electrolytes (CSEs) to meet the high-performance requirements of current lithium batteries. This work prepares silicon dioxide (SiO₂) via in-situ hydrolysis within a polyvinylpyrrolidone (PVP) polymer matrix through electrospinning, successfully constructing inorganic fiber fillers with a three-dimensional (3D) network structure. The introduction of 3D-structured SiO₂ can enhance anion adsorption through the Lewis acid sites of silicon species and reduce the Li ⁺ complexation effect by participating in the interactions between carbonyl oxygen and lithium ions. Therefore, the three-dimensional network structure enables the formation of continuous lithium-ion transport pathways, and the as-prepared CSEs exhibit a high ionic conductivity (1.32 × 10⁻⁴ S cm⁻¹ at 30 °C), a high lithium-ion transference number of 0.51, and a wide electrochemical stability window (5.29 V). With these excellent properties, the CSEs enable stable lithium plating/stripping with uniform deposition. Consequently, the LiFePO₄/Li quasi-solid-state battery delivers outstanding cycling performance, with a capacity retention of 91.14% after 300 cycles at 0.2 C.