Passivated Zn Powders as Metal Anode

Abstract

Impacted by heavy corrosion and poor connections, zinc (Zn) powders have rarely been considered as the raw materials of Zn-ion aqueous batteries (ZABs). Nonetheless, the ease of controlling loadings of Zn powders entitles ZABs to better capacity match between negative and positive electrodes. Here, a simple and rapid chemical solution passivation method is reported, which leads to a thin, dense, and conformal passivation layer on Zn powder surface. The passivation layer suppresses parasitic reactions of Zn powder anode, mitigates corrosions, and extends the calendar life. Mixing with well-dispersed carbon nanotubes, the passivated Zn powder anode is able to cycle 100 h under 3 mA cm⁻² and 3 mAh cm⁻² at depth of discharge of 41.3%. Besides, the anode with negative/positive electrode capacity ratio of 5.95 improves the energy density of the Zn powder||MnO₂ full cell to 70 Wh Kg⁻¹. Such a simple “one-step” passivation method is believed to be a “drop-in” technique applied in the scalable manufacture of ZABs.