Rational screening of metal coating on Zn anode for ultrahigh-cumulative-capacity aqueous zinc metal batteries

Aqueous zinc metal batteries feature intrinsic safety, but suffer from severe dendrite growth and water-derived side reactions. Many metal coatings have been explored for stabilizing Zn metal anode via a trial-and-error approach. Here, we propose an exercisable way to screen the potential metal coating on Zn anodes in view of de-polarization effect and dendrite-suppressing ability theoretically. As an output of this screening, cadmium (Cd) metal is checked experimentally. Therefore, symmetric Zn||Zn cells using Cd coated Zn (Zn@Cd) exhibit an ultra-long cycle life of 3500 h (nearly 5 months) at a high current density of 10 mA cm−2, achieving a record-high cumulative capacity (35 A h cm−2) compared to the previous reports. The full cells of Zn@Cd||MnO2 display a markedly improved cycling performance under harsh conditions including a limited Zn supply (N/P ratio = 1.7) and a high areal capacity (3.5 mA h cm−2). The significance of this work lies in not only the first report of Cd coating for stabilizing Zn metal anode, but also a feasible way to screen the promising metal materials for other metal anodes.