Unveiling the Origin of Alloy-Seeded and Nondendritic Growth of Zn for Rechargeable Aqueous Zn Batteries

Rechargeable aqueous zinc anodes have gained tremendous attention because of their merits of intrinsic safety, low cost, and high theoretical volumetric capacity (5854 mAh cm^–3 for Zn metal). In aqueous electrolytes, zinc anodes suffer from severe dendritic metal deposition. The regulation of Zn by inducing Zn-alloying metals has been reported. However, the underlying mechanisms have remained elusive. Here, for the first time, we did a comprehensive analysis to elucidate the mechanisms for the seeded and nondendritic growth of Zn on alloy anodes. We achieved uniform Zn deposition by introducing a Zn-alloying and soluble metal, Ag, on Zn anodes. Due to a shift of thermodynamic potential and the spatial confinement, the Ag-modified Zn anode exhibited improved overall cycling performance compared with previous deep-cycle Zn anodes. Furthermore, the seeded Zn deposition was visualized in operando for the first time using an optical microscope. The alloy-seeding design principle here can potentially be applied to improve the rechargeability of other metal anodes.