Cascade Synergy of Bulk and Interfacial Zn 2+ Transport for a Self‐Healing Hydrogel Electrolyte with Ultrahigh Conductivity in High‐Rate Zinc‐Ion Energy Storage

ABSTRACT Self‐healing hydrogel electrolytes typically sacrifice ionic conductivity because strong dynamic bonds responsible for healing create viscous matrices, which impede bulk ion diffusion without enhancing solid‐solid junction transport. Here, we break this deadlock by engineering a poly(vinyl alcohol)‐borax (PVA‐B) network hosting Zn(OTf) 2 , which delivers an ionic conductivity of 45.77 mS cm −1 , one of the highest values ever reported among self‐healing hydrogel electrolytes. Crucially, we reveal a cascade synergy bridging bulk and interfacial ion transport. Within the electrolyte matrix, the PVA‐B framework establishes a heterogeneous electrostatic landscape that orients Zn 2+ migration via a low‐energy‐barrier hopping mechanism, maximizing bulk conduction. Concurrently, the matrix promotes the formation of a robust Zn 2+ ‐conductive solid‐electrolyte interphase (SEI), which accelerates interfacial Zn 2+ diffusion. Beyond this dual boost, the hydrogel disrupts the native H‐bond network to reconfigure the Zn 2+ solvation sheath, suppressing parasitic reactions and reducing the desolvation penalty. Consequently, zinc‐ion hybrid capacitors using this electrolyte achieve 30 000 cycles at 10 A g −1 with minimal capacity loss and robust self‐healing. This work demonstrates a viable pathway to decouple self‐healability from ion‐transport constraints, advancing the design of durable flexible zinc‐based energy storage.