Effects of indium, gallium, or bismuth additions on the discharge behavior of Al-Mg-Sn-based alloy for Al-air battery anodes in NaOH electrolytes

In this paper, the electrochemical performances of Al 0.5-Mg 0.1-Sn (wt%), Al 0.5-Mg 0.1-Sn 0.05 In (wt%), Al 0.5-Mg 0.1-Sn 0.05 Ga (wt%) and Al 0.5-Mg 0.1-Sn 0.05 Bi (wt%) alloys were investigated through electrochemical techniques and microstructure observation in 4 M NaOH solution. The results indicate that Al 0.5-Mg 0.1-Sn 0.05 In (wt%) alloy has the best discharge performance among all alloys, followed by Al 0.5-Mg 0.1-Sn 0.05-Bi (wt%) alloy, both of which is better than Al 0.5 Mg 0.1-Sn 0.05-Ga (wt%) alloy. This is due to the fact that the addition of indium to the Al 0.5-Mg 0.1-Sn-based alloy improves the discharge activity of the alloy while increasing its anodic efficiency. Although the addition of gallium or bismuth to this alloy increases the discharge activity, it reduces the efficiency of the anode, especially the addition of gallium resulting in severe intergranular corrosion of the alloy anode.