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.