Dictating Zn²⁺ Transport Kinetics via Versatile Ionic Covalent Organic Framework for Robust Zn Metal Anodes

Covalent organic frameworks (COFs) offer a promising platform in regulating ion transport and stabilizing electrode-electrolyte interfaces owing to their tailorable porosity and versatile moiety. Compared to widely employed neutral COFs, ionic COFs (iCOFs) harness strong electrostatic interactions to selectively interact with target ions, thereby helping accelerate ion-pair dissociation. Furthermore, the charged backbones of iCOFs induce interlayer electrostatic repulsion, driving spontaneous exfoliation and hence promoting ion transport kinetics. Capitalizing upon these advantages, we in situ engineer a low-crystallinity iCOF interfacial membrane over Zn anode. The guanidinium moieties within the framework immobilize water molecules through H-bond interactions, effectively suppressing parasitic side reactions. Concurrently, coulombic interactions between the positively charged backbone and SO₄ ^2- facilitate Zn²⁺ dissociation, enabling stable ion transport and uniform Zn deposition. Benefiting from the improved electrochemical stability of modified Zn anode, the as-assembled Zn metal pouch cell delivers a reversible capacity of ∼0.35 Ah g^-1 with a 98.72% capacity retention over prolonged cycling. This work establishes a paradigm for leveraging iCOFs to regulate Zn²⁺ transport kinetics toward next-generation energy storage systems.