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 Zn²⁺ 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.