The role of gallium and indium in improving the electrochemical characteristics of Al–Mg–Sn-based alloy for Al–air battery anodes in 2 M NaCl solution

The electrochemical discharge behaviours of Al–0.5Mg–0.1Sn (wt%), Al–0.5Mg–0.1Sn–0.05In (wt%), Al–0.5Mg–0.1Sn–0.05Ga (wt%) and Al–0.5Mg–0.1Sn–0.05Ga–0.05In (wt%) alloys are investigated in 2 M NaCl solution. Based on electrochemical responses and microstructure observations, the influence mechanism of indium and gallium on the discharge behaviour of Al–Mg–Sn-based anode is clarified. The result indicates that Al–0.5Mg–0.1Sn–0.05Ga–0.05In (wt%) anode has the best discharge characteristics. Adding gallium accelerates active dissolution of Al–Mg–Sn anode. And adding indium leads to the appearance of discharge products (ie, In and In(OH)₃), which inhibits the self-corrosion reaction of the anode. The peak power and peak energy density of Al–0.5Mg–0.1Sn–0.05Ga–0.05In (wt%) anodes reach approximately 92.96 mW cm⁻² (at 140 mA cm⁻²) and 3385.4 W h kg⁻¹ (at 20 mA cm⁻²) in 2 M NaCl solution, which increases by 447% and 104% compared with that of Al–0.5Mg–0.1Sn (wt%) anodes, respectively. Therefore, Al–Mg–Sn–Ga–In anodes could be a good and promising choice for high-speed discharge Al–air batteries in brine electrolytes.