An Unprecedented Fireproof, Anion‐Immobilized Composite Electrolyte Obtained via Solidifying Carbonate Electrolyte for Safe and High‐Power Solid‐State Lithium‐Ion Batteries

Abstract The update of electrolytes from a liquid state to a solid state is considered effective in improving the safety and energy density of lithium‐ion batteries (LIBs). Although numerous efforts have been made, solid‐state electrolytes’ (SSEs) insufficient charge transfer capability remains a significant obstruction to practical applications. Herein, a fireproof and anion‐immobilized composite electrolyte is designed by solidifying carbonate electrolyte, exhibiting superior Li‐ion conductivity (11.5 mS cm −1 at 30 °C) and Li‐ion transference number (0.90), which endows LIBs excellent rate capability and cycling stability. Elaborate characteristics and theoretical calculations demonstrate the presence of robust anion‐molecule coordination (composed of lithium bond and Coulomb force) enables a more efficient ion transport, where the mobility of Li + ion is enhanced meanwhile the anions are immobilized. This work highlights how the strong interactions between electrolyte components can be used to simultaneously regulate the migration of Li + ion and anion, and realize a one‐step conversion of inflammable liquid‐state electrolyte to nonflammable solid‐state electrolyte.