Covalent Organic Framework with Multi‐Cationic Molecular Chains for Gate Mechanism Controlled Superionic Conduction in All‐Solid‐State Batteries

Although solid-state batteries (SSBs) are high potential in achieving better safety and higher energy density, current solid-state electrolytes (SSEs) cannot fully satisfy the complicated requirements of SSBs. Herein, a covalent organic framework (COF) with multi-cationic molecular chains (COF-MCMC) was developed as an efficient SSE. The MCMCs chemically anchored on COF channels were generated by nano-confined copolymerization of cationic ionic liquid monomers, which can function as Li⁺ selective gates. The coulombic interaction between MCMCs and anions leads to easier dissociation of Li⁺ from coordinated states, and thus Li⁺ transport is accelerated. While the movement of anions is restrained due to the charge interaction, resulting in a high Li⁺ conductivity of 4.9×10^-4 S cm^-1 and Li⁺ transference number of 0.71 at 30 °C. The SSBs with COF-MCMC demonstrate an excellent specific energy density of 403.4 Wh kg^-1 with high cathode loading and limited Li metal source.