Regulating Interfacial Ion Migration via Wool Keratin Mediated Biogel Electrolyte toward Robust Flexible Zn‐Ion Batteries

Abstract Aqueous Zn‐ion batteries (ZIBs) have emerged as a promising energy supply for next‐generation wearable electronics, yet they are still impeded by the notorious growth of zinc dendrite and uncontrollable side reaction. While the rational design of electrolyte composition or separator decoration can effectively restrain zinc dendrite growth, synchronously regulating the interfacial electrochemical performance by tackling the physical delamination venture between electrode and electrolyte remains a major obstacle for high‐performance wearable aqueous ZIB. Herein, a category of hybrid biogel electrolyte containing carrageenan and wool keratin (CWK) is put forward to regulate the interfacial electrochemistry in aqueous ZIB. Systematic electrochemical kinetics analyses and ex situ scanning electrochemical microscopy (SECM) characterizations achieve comprehensive understanding of the keratin enhanced interfacial Zn 2+ redox reaction. Thanks to the keratin triggered selective ion permeability, the as‐designed CWK hybrid biogel electrolyte manifests a promoted Zn 2+ transference number and excellent reversibility of Zn plating/stripping and outstanding Zn utilization (average Coulombic efficiency ≈98%). More impressively, the CWK hybrid biogel electrolyte also demonstrates cathode side‐reaction depression and strengthened interfacial adhesion while assembled into a quasi‐solid‐state flexible ZIB. This work offers a strategy to synchronously solve concurrent challenges for both of Zn anode and cathode toward realistic wearable aqueous ZIB.