Ag_<i>x</i>Zn_<i>y</i> Protective Coatings with Selective Zn²⁺/H⁺ Binding Enable Reversible Zn Anodes

Abstract

Zinc (Zn) metal anodes suffer from the dendrite growth and hydrogen evolution reaction (HER) in classical aqueous electrolytes, which severely limit their lifespan. We propose a rational design of Ag_<i>x</i>Zn_<i>y</i> protective coatings with selective binding to Zn²⁺ against H⁺ to simultaneously regulate the Zn growth pattern and the HER kinetics. We further demonstrate that by tuning the composition of the Ag_<i>x</i>Zn_<i>y</i> coating the Zn deposition behavior can be readily tuned from the conventional plating/stripping (on Zn-AgZn₃ coating) to alloying/dealloying (on Ag-AgZn coating), resulting in precise control of the Zn growth pattern. Moreover, the synergy of Ag and Zn further suppresses the competitive HER. As a result, the modified Zn anodes possess a significantly enhanced lifespan. This work provides a new strategy for enhancing the stability of Zn and potentially other metal anodes by precisely manipulating the binding strength of protons and metal charge carriers in aqueous batteries.