Gold-Nanolayer-Derived Zincophilicity Suppressing Metallic Zinc Dendrites and Its Efficacy in Improving Electrochemical Stability of Aqueous Zinc-Ion Batteries

Abstract

Herein, an Au-coating layer adjusted on the surface of a Zn metal electrode that effectively suppresses the dendrite growth as well as the mechanisms underlying the dendrite suppression as a result of the zincophilic character of Au is introduced. For the Au-coated Zn metal symmetric cell, uniform deposition of Zn-derived compounds was revealed by operando synchrotron tomography. Microscopic studies demonstrate that the Au-coating layer is induced to form a new Zn-Au alloy during the initial Zn deposition, resulting in stabilized long-term stripping/plating of Zn via the 'embracing effect' that intimately accommodates Zn deposition for further cycles. This property supports the successful operation of symmetrical cells up to 50 mA cm-2. According to Zn electrodeposition simulation, it is verified that the suppression of dendrite growth is responsible for the electro-conducting Au nanolayer that uniformly distributes the electric field and protects the Zn electrode from corrosion, ultimately promoting uniform Zn growth. The compatibility of the Au-coating layer for full cell configuration is verified using NaV3O8 as a cathode material over 1 000 cycles. This finding provides a new pathway for the enhancement of the electrochemical performance of ZIBs by suppressing the dendritic growth of Zn by means of a zincophilic Au nanolayer. From the initial Zn deposition, a Zn-Au alloy grows from the Au-coating layer. This further results in smooth Zn deposition, which stabilizes long-term Zn stripping/plating without Zn dendrite via the 'embracing effect'.image