Uniform and oriented zinc deposition induced by artificial Nb2O5 Layer for highly reversible Zn anode in aqueous zinc ion batteries

Abstract

Zn metal has recently emerged as a promising candidate for stable and reversible anode in aqueous rechargeable batteries. However, despite the high reversibility of Zn metal in aqueous media, Zn metal anode utilization is limited owing to unavoidable dilemmas, such as dendrite growth, hydrogen gas evolution, and “dead Zn”, eventually leading to battery breakdown. Herein, we propose a Nb2O5 film as an effective coating layer to guarantee uniform ion flux and a rapid transportation pathway for Zn ions through Maxwell–Wagner polarization, resulting in homogeneous Zn electrodeposition under the Nb2O5 layer. The artificial Nb2O5 layer coated on the Zn surface (Nb2O5@Zn) acted as a guide for Zn deposition, enabling a dense and uniform morphology of electrodeposited Zn oriented in a specific direction. The symmetric Nb2O5@Zn anode system exhibited stable plating/stripping for up to 1000 h. Outstanding durability and resilience (220 h at 5 mA cm−2/5 mAh cm−2) and rapid plating/stripping with excellent recovery (returning to 1 from 10 mA cm−2) were verified under harsh cycling conditions. The excellent characteristics of Nb2O5 layer resulted in high electrochemical stability and performance for a full cell with a VO2 cathode for practical applications.