A Covalent Organic Framework With Staggered Topology for Mimetic Transmembrane Transport of Hydrated Ions

In biological systems, hydrated-ions cross protein channels with exceptional high efficiency through a structural dehydration-compensation mechanism, where protein conformational adjustments contract the channel and enable electron-rich sites to coordinate with ions, offsetting their dehydration energy without external energy input. In this work, we discovered that a typical β-ketoenamine-linked covalent organic framework (COF) with staggered-stacking architectures exhibits a similar mechanism. Although COFs lack dynamic conformational adjustments, the AB-staggered topology generates convergent channels enriched with carbonyl groups, which provide out-sphere-like multisite interactions with hydrated ions, partially compensating for the hydration dissociation energy and enabling rapid and efficient ion transport with low solvation. When employed as separators in aqueous zinc batteries, AB-staggered COF membranes simultaneously suppress parasitic reactions and zinc dendrite formation. Zn anodes paired with these COF membranes exhibit markedly enhanced electrochemical cycling reversibility with stable Zn stripping/plating for over 5000 h in a conventional ZnSO₄ electrolyte without any additives, outperforming most reported aqueous battery separators. This study identifies and experimentally validates rapid, low-solvation hydrated-ion transport in COFs via a biomimetic structural dehydration-compensation mechanism, establishing a conceptual foundation for the rational design of high-performance COF membranes in multiple fields, including but not limited to electrochemical energy storage, chemical separation, and catalytic systems.