Highly stable and durable Zn-metal anode coated by bi-functional protective layer suppressing uncontrollable dendrites growth and corrosion

Abstract

Although rechargeable aqueous zinc batteries (RAZB) have experienced their renaissance recently, Zn-metal anodes still suffer from serious dendrites growth and inevitable Zn corrosion in mild aqueous electrolyte during cycling. It is imperative to provide a simple and effective strategy to address the above problems. Herein, we have developed a one-step strategy to in-situ fabricate a homogeneous and stable protective layer composing of dense ZnF2 and embedded Cu particles on the electrode at room temperature. The ZnF2-Cu protective layer with both high Zn2+ transfer number (0.758) and homogeneous nucleation sites (Cu particles) with excellent zinc affinity exhibits remarkable synergistic effect for dual purpose: 1) to effectively inhibit severe dendrites growth via regulating Zn nucleation and 2) to suppress Zn corrosion and the accompanying hydrogen evolution by preventing Zn metal surface from aqueous electrolyte attacking. As a result, the ZnF2-Cu@Zn anodes can maintain stable cycling for>1600 h with super low over-potential and increased average coulombic efficiency (CE). In addition, the ZnF2-Cu@Zn || V2O5 full cells provide a reversible capacity of 103 mA h g−1 after 2000 cycles at an ultra-high current density of 10 A g−1. This work proposes a promising approach for the practical application of RAZB in the future.