Phosphorylated Covalent Organic Framework Membranes Toward Ultrafast Single Lithium‐Ion Transport

Abstract Developing all‐solid‐state electrolytes, the chips for lithium‐metal batteries, with superior electrochemical and mechanical properties awaits the disruptive materials. Herein, ionic covalent organic framework membranes are explored as solid‐state electrolytes for single Li + conduction. In the membrane, the anion groups act as Li + transporter, determining Li + binding capacity and releasing ability, whereas the oxygen‐containing groups act as Li + co‐transporter, creating relay sites between adjacent Li + transporters for rapid hopping. The membrane exhibits an unprecedented Li + conductivity of 1.7 mS cm −1 with a Li + ‐transference number close to unity at room temperature. Additionally, the membrane possesses high flexibility, low interfacial resistance, and excellent cycling performance at room temperature. This work paves an unprecedented path for the advancement of next‐generation Li + conductors in solid‐state electrolytes.