Effects of trace amounts of Sn, Ca, and Cu on the electrochemical properties and discharge performance of Mg-2Zn-1Gd-0.5Zr as an anode for Mg-air battery

To explore the effect of microalloying on Mg-2Zn-1Gd-0.5Zr (wt.%) (ZG21), the discharge characteristics of ZG21 and ZG21-0.2X (X = Sn, Ca, Cu) were investigated comparatively. Sn solid solution into α-Mg, reduces galvanic corrosion and chunk effect, and greatly improves the discharge efficiency of ZG21. The efficiency of ZG21-0.2Sn are obtained at 20 mA cm−2 with 63.5%. Ca addition makes the open circuit potential more negative and forms Ca2Mg6Zn3 phase to further promote the activity, and because of the loose and easy to exfoliate products, in summary, ZG21-0.2Ca discharge voltage is higher which can reach 1.268 V at 10 mA cm−2. The addition of Cu to form the MgZnCu phase increases the activity and also reduces the grain size, which should be beneficial to the discharge performance, but still the discharge performance is bad due to severe hydrogen evolution. The addition of Sn and Ca provides new ideas and options composition design of Mg-air battery anodes.