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 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.