Composite solid electrolytes hold the promise of merging complementary merits of solid polymer electrolytes and ceramic fillers to achieve solid batteries with comprehensive performance. Especially, three-dimensional inorganic electrolyte frameworks, such as Li₇La₃Zr₂O₁₂, with fast and continuous lithium ion migration channels demonstrate great promise in composite solid electrolytes. Nevertheless, brittle ceramic conductor skeletons are incapable of providing sufficient mechanical adaptability, which restricts their practical application. Herein, a flexible, ion-conducting network which integrates Li₇La₃Zr₂O₁₂ nanoparticles in polyacrylonitrile nanofibers is fabricated through electrospinning method. Subsequently, a composite electrolyte with three-dimensional continuous structure is achieved via in situ polymerizing of 1,3-dioxolane within the ionic conduction framework. The highly conductive Li₇La₃Zr₂O₁₂ reinforced polymer nanofibers are not only available to promote transportation of lithium ion, but also provide structural flexibility and mechanical robustness for composite electrolyte. Accordingly, the obtained composite electrolyte combines enhanced room temperature ionic conductivity (4.38 × 10⁻⁴ S·cm⁻¹) with structural flexibility and mechanical robustness, supported by exceptional interfacial compatibility with lithium metal, enabling ultra-stable lithium symmetric battery operation (3000 h at 0.1 mA·cm⁻²). Furthermore, as-prepared LiFePO₄ and LiCoO₂/lithium solid-state batteries deliver high capacity retention of 96% after 350 cycles and capacity retention of 82% after 600 cycles at room temperature. This work provides a new avenue in design of advancing composite solid electrolytes.

Although lithium metal is considered a promising anode for advanced Li-S and Li-air batteries, the uncontrolled dendrite growth and infinite volume change impede its practical application. Herein, we report an ideal framework composed of carbonized bacterial cellulose (CBC) nanofibers, which shows intrinsic lithiophilicity to molten lithium without any lithiophilic surface modification. The wetting behavior of molten lithium can be significantly improved because its surface functional groups provide thermodynamical driving force, and the high surface roughness derived from nanocracks leads to rapid infusion in kinetics. The hybrid anode exhibits long cycle life up to 2000 h and excellent deep stripping–platting capacity up to 20 mAh·cm⁻². When the anode is assembled with LiFePO₄ cathode, the full cell delivers a good cycling stability up to 700 cycles. This is attributed to the intrinsic lithiophilic scaffold, which can not only lower the nucleation barrier of Li and provide uniform nucleation sites for stable Li stripping/plating, but also offer interspace to accommodate volume fluctuation of lithium during long cycling. This work provides a new manner to achieve a series of intrinsic lithiophilic carbon skeletons based on the large family of biomass materials and organic materials.