Ion‐Selective Transport via Nanoconfined Differential Interfacial Friction in a Dielectric‐Engineered Covalent Organic Framework With Sectionalized Chemical Environments

ABSTRACT Developing solid‐state electrolytes (SSEs) that concurrently deliver high ionic conductivity, excellent ion selectivity, and robust electrochemical/thermal stability remains a central challenge for safe, high‐energy‐density solid‐state batteries (SSBs). Here, an all‐solid‐state covalent organic framework electrolyte with sectionalized chemical environments (SCE‐COF) is reported, constructed via nanoconfined copolymerization of a highly dielectric monomer within COF nanochannels. The resulting architecture affords a nano‐confined molecular interface that integrates electron‐rich polar short chains that form abundant Li + hopping sites with electron‐deficient pore‐wall regions that immobilize anions through specific hydrogen‐bonding interactions, thereby enabling efficient and differential ion transport decoupled from strongly bonded solvation cage and polymer segmental motion. Benefiting from these synergistic effects, SCE‐COF achieves ionic conductivity of 1.05 × 10 −3 S cm −1 at 30°C, a high Li + transference number of 0.73 and a wide electrochemical window (4.87 V vs Li + /Li). Finally, all‐solid‐state full cells employing SCE‐COF deliver a high specific energy density of 442.0 Wh kg −1 under a controlled lithium source at ambient temperature.