Effect of yttrium and calcium additions on electrochemical behaviors and discharge performance of AZ80 anodes for Mg−air battery

The effects of yttrium (Y) and yttrium + calcium (Y+Ca) additions on the electrochemical properties and discharge performance of the as-extruded Mg−8Al−0.5Zn−0.2Mn (AZ80) anodes for Mg−air batteries were investigated. The results show that the addition of 0.2 wt.% Y increased the corrosion resistance and discharge activity of AZ80 anode. This was attributed to the fine and spherical β-Mg17Al12 phases dispersing evenly in AZ80+0.2Y alloy, which suppressed the localized corrosion and severe “chunk effect”, and facilitated the rapid activation of α-Mg. Combinative addition of 0.2 wt.% Y and 0.15 wt.% Ca generated grain refinement and a reduction of the β-Mg17Al12 phase, resulting in a further enhancement in discharge voltage. However, the incorporation of Ca in Mg17Al12 and Al2Y compounds compromised the corrosion resistance and anodic efficiency of AZ80+0.2Y+0.15Ca anode. Consequently, AZ80+0.2Y anode exhibited excellent overall discharge performance, with the peak discharge capacity and anodic efficiency of 1525 mA·h·g−1 and 67% at 80 mA/cm2, 13% and 14% higher than those of AZ80 anode, respectively.