Self-assembled silica-cellulose-ether ternary nanocomposite electrolytes for robust quasi-solid-state lithium metal batteries

Solid electrolytes are a key enabling technology for the safe operation of Li-metal batteries, as they can suppress side reactions and Li dendrites. However, their microstructural heterogeneity and metastability largely restrict their mechanical and electrochemical properties. Herein we report a one-pot sol-gel self-assembly for in-situ constructing silica-cellulose-ether nanocomposite as solid-state electrolytes in Li-metal batteries. The obtained composite features mesoporous silica nanoparticles grafted to functional cellulose nanofibers to form cross-linked frameworks, in which liquid ether electrolytes are in-situ immobilized. By regulating chemical interactions between three nanocomponents for optimizing electrolyte's distribution and ionic conduction, such composite design enables excellent electrochemical properties, showing rapid Li⁺ ionic conductivity (6.9 × 10⁻⁴ S cm⁻¹) and high electrochemical oxidation tolerance (4.87 V vs Li/Li⁺). Notably, the quasi-solid-state Li-metal batteries using composite membranes exhibit outstanding battery performance: Li//LiFePO₄ cell delivers an ultra-high capacity retention of 97.5 % after 200 cycles, and Li//RuO₂-O₂ cell exhibits an extended cycle-life over 300 cycles.