Reusable and Robust Hydrogel With Dynamic Sacrificial S─S Bonds: In Situ Construction of an Integrated SEI/Hydrogel...

The trade-off among mechanical strength, ionic conductivity, and interfacial stability remains a core challenge for high-performance hydrogel interfacial layers. Herein, an integrated SEI/polyurea-polyurethane hydrogel (PUMA) interface was constructed on the Zn anode via in situ gelation coupled with interfacial electrochemical reduction. Polyurea-polyurethane hard segments containing octuple H-bonds, Zn²⁺ coordination bonds, and dynamic S─S bonds reinforce PUMA through multi-level energy dissipation and suppress side reactions by regulating interfacial water. Polyanionic soft segments rich in carboxyl and sulfonic acid groups construct low-barrier, ion-selective pathways, optimizing Zn²⁺ transport and deposition by solvation regulation and mitigation of concentration polarization. Crucially, interfacial sacrificial S─S bonds undergo cleavage during electrochemical reduction, generating an integrated SEI/PUMA interface with enhanced interfacial stability. The dynamic polyanionic network also blocks polyiodide shuttling and enables thermal reprocessing. Consequently, PUMA@Zn achieves a Zn²⁺ transference number of 0.79 and symmetric cell cycling for 5080 h (1 mA cm^-2 and 0.5 mAh cm^-2). PUMA@Zn//I₂ cells retain 88% capacity after 43 000 cycles at 4 A g^-1 and operate for over 11 000 cycles even at high iodine loading (16.58 mg cm^-2). This strategy provides a novel pathway to achieve robust, ion-conductivity, and chemically bonded hydrogel-metal interfaces for high-performance aqueous batteries.