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

Aqueous Zn‐ion batteries (AZIBs) are widely regarded as the ideal candidate for large‐scale energy storage systems. However, Zn metal anode has long faced challenges, such as: hydrogen evolution reaction, dendrite growth, surface corrosion. Herein, we report the development of a self‐healable and strongly adhesive polymer protective layer for AZIBs, which is achieved by polymerizing a natural small molecule, thioctic acid (TA) on Zn surface. Thanks to the strong and spontaneous affinity between Zn metal surface and S atoms on polymer chains, this polymer protective layer can firmly and dynamically adhere to the Zn surface. Thus, even at a thickness of only <1 μm, the protective layer can exhibit a strong adhesion force of up to 10.5 N with Zn surface, while the abundant carboxyl groups in protective layer can form intramolecular hydrogen bonds, endowing its high self‐healing property and enhancing its strength. Such a protective layer effectively inhibits the dendrite growth physically, regulates the Zn2+ migration and deposition behavior chemically. Therefore, the symmetric cells can be cycled for ~1000 h at the current density of 1.0 mA cm‐2 and 5.0 mA cm‐2, respectively. The full cells with NH4V4O10 can also run stably for 1000 cycles with a high capacity retention.