A Dynamic Self‐Healing Protective Layer Enabling Stable Zinc Ion Batteries through Strong Zn‐S Affinity and Intramolecular Hydrogen Bonding

Abstract Aqueous Zn‐ion batteries (AZIBs) are promising for large‐scale energy storage, yet Zn metal anodes face issues like hydrogen evolution, dendrite growth, and corrosion. Herein, we develop a self‐healable, adhesive polymer layer for AZIBs by polymerizing thioctic acid (TA) on Zn surfaces. Thanks to the strong and spontaneous affinity between Zn metal surface and S atoms on polymer chains, this protective layer can firmly and dynamically adhere to the Zn surface. Thus, even at a thickness of <1 µm, the protective layer exhibits a strong adhesion force of up to 10.5 N with Zn surface, while the abundant carboxyl groups in the protective layer can form intramolecular hydrogen bonds, endowing its high self‐healing property and enhancing its strength (Young's modulus reaches 15.1 GPa). Such a protective layer effectively inhibits the dendrite growth physically and regulates the Zn 2+ migration and deposition behavior chemically. Therefore, the symmetric cells can be cycled for more than 1000 h at the current densities of 1.0 and 5.0 mA cm −2 , respectively. Full cells with NH4V4O10 also run stably for 1000 cycles with a high capacity retention. This work offers a promising strategy for designing multifunctional polymer coating towards high‐stability and long‐cycling AZIBs.