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

Abstract

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.