Uniform Zn Deposition Achieved by Ag Coating for Improved Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (ZIBs) are considered as a promising energy storage system due to their low cost and high safety merits. However, they suffer from the challenge of uncontrollable dendrite growth due to a non-uniform zinc deposition, which increases internal resistance and causes battery failure. Herein, Ag coating fabricated by a facile surface chemistry route on zinc metal was developed to guide uniform zinc deposition. Ag-coated Zn shows improved electrolyte wettability, a small zinc deposition overpotential, and fast kinetics for zinc deposition/dissolution. Direct optical visualization and scanning electron microscopy images show uniform zinc deposition due to the introduction of Ag coating. As a result, the Ag-coated Zn anode can sustain up to 1450 h of repeated plating/stripping with a low overpotential in symmetric cells at a current density of 0.2 mA cm^-2, while an improved performance is realized for full cells paired with a V₂O₅-based cathode. This work provides a facile and effective approach to improve the electrochemical performance of ZIBs.