Self‐Adapting and Self‐Healing Hydrogel Interface with Fast Zn2+ Transport Kinetics for Highly Reversible Zn Anodes

Abstract Construction of polymer‐based artificial solid‐electrolyte interphase films on Zn metal anode holds great potential in the suppression of both dendrite growth and side reaction in rechargeable aqueous Zn‐ion batteries. However, the traditional polymer films suffer from the critical issues of sluggish Zn 2+ transport kinetics and rigid interface. Herein, zinc alginate (ZA) hydrogel is designed and prepared as a dynamic interface and Zn 2+ redistributor on Zn anode via in situ cross‐linking reaction. The zincophilic and negatively charged carboxyl groups of ZA promote the transport of Zn 2+ ions along a “Z‐type” pathway, the repulsion of free SO 4 2‐ anions, and the desolvation of Zn 2+ ions, consequently leading to the homogeneous deposition of Zn and the effective suppression of side reaction. Additionally, the dynamic flexibility of ZA hydrogel endows the Zn anode with self‐adapting interface to accommodate the volume variation and repair the possible ruptures, thereby guaranteeing the long‐term cycling stability. Assisted by the ZA layer, the Zn anode achieves a prolonged lifespan over 2200 h without the formation of Zn dendrites and by‐products. Outstanding cycling stability is also demonstrated for the Zn anode when coupled with MnO 2 cathode, further demonstrating its prospects for practical application.