Ag-Modified Cu Foams as Three-Dimensional Anodes for Rechargeable Zinc–Air Batteries

Rechargeable zinc–air batteries are typical environment-friendly energy storage devices with high energy density and low cost. Nevertheless, dendrite formation and self-corrosion of zinc anode directly reduce battery performance. Herein, we report a novel Cu foam substrate with uniform Ag nanoparticles deposited on the surface as three-dimensional (3D) anode in rechargeable zinc-air battery and battery stacks for the first time. Tafel and linear scanning voltammetry measurements exhibit the Ag deposited on Cu foam suppresses hydrogen evolution reaction and reduces corrosion current density on the anode. Ag-modified three-dimensional anode is used in a primary zinc-air battery with 200 mAh anode capacity and Ag–Cu catalyzed cathode, which demonstrates a high specific capacity of 676 mAh gZn–1, an energy density of 786 Wh kgZn–1 and a high zinc utilization of 87%. Afterward, Ag-modified three-dimensional anode is used in a rechargeable zinc–air battery, which presents a Coulombic efficiency of 94% after 80 cycles with 2 h cycle period. Besides, Ag-modified three-dimensional anode is free of Zn dendrites at different depth of discharge from 5% to 20%. When two rechargeable zinc–air batteries are connected in both series and parallel, these batteries show a high energy efficiency of 55% and 60%, respectively, and deliver stable cycling over 40 cycles. The stable cycling performance can be attributed to Ag nanoparticles on the substrate surface, which regulate the Zn deposition uniformly in the voids between Cu foam skeleton and prevent dendrite formation by providing continuous uniform electronic transmission channels.