Electrochemical Migration of Zincophilic Metals for Stress Mitigation and Uniform Zinc Deposition in Aqueous Zinc-Ion Batteries

The propensity of zinc (Zn) to form irregular electrodeposits at liquid-solid interfaces emerges as a fundamental barrier to high-energy, rechargeable batteries that use zinc anodes. So far, tremendous efforts are devoted to tailoring interfaces, while atomic-scale reaction mechanisms and the related nanoscale strain at the electrochemical interface receive less attention. Here, the underlying atomic-scale reaction mechanisms and the associated nanoscale strain at the electrochemical alloy interface are investigate, using gold-zinc alloy protective layer as a model system. Leveraging multiscale spatial resolution imaging techniques, it is observed that gold element migration occurs universally at liquid-solid interfaces and plays a pivotal role during the galvanic process. Gold (Au) migrates from the gold-zinc alloy layer to the surface, where it accumulates at the interface. The remaining gold-zinc alloy layer forms a porous microstructure while maintaining its interlayer position, leading to strain relaxation during zinc plating. This zincophilic interlayer effectively promotes uniform zinc nucleation while simultaneously enhancing the wettability of the electrodes in the aqueous electrolyte. Consequently, this modification strategy improves the cycling stability of zinc batteries. These findings significantly advance the fundamental understanding of the micro-reaction mechanisms at the zinc anode interface.