Effect of Ga on microstructure and electrochemical performance of Al–0.4Mg–0.05Sn–0.03Hg alloy as anode for Al–air batteries

Abstract

The effects of 0.01 wt.% Ga on microstructure and electrochemical performance of Al–0.4Mg–0.05Sn– 0.03Hg anodes in NaOH solutions were investigated. Potentiodynamic polarization, electrochemical impedance spectroscopy, and galvanostatic discharge tests were used to assess the electrochemical performance of the Al–Mg–Sn–Hg–Ga anodes. The results show that the addition of 0.01 wt.% Ga in Al–0.4Mg–0.05Sn–0.03Hg anode enhances its corrosion resistance and discharge activity. It is benefited from the refined second phases and homogenous microstructure of Al–Mg–Sn–Hg–Ga anode, which restrains the local crystallographic corrosion and chunk effect. Compared with Al–Mg–Sn–Hg anode, the corrosion current density and the mass loss rate of Al–Mg–Sn–Hg–Ga anode decrease by 57% and 93%, respectively. When discharging at the current density of 20 mA/cm2, the discharge voltage, current efficiency and specific capacity of the single Al–air battery with Al–0.4Mg–0.05Sn–0.03Hg–0.01Ga anode are 1.46 V, 33.1%, and 1019.2 A·h·kg−1, respectively. The activation mechanism of Ga on Al–Mg–Sn–Hg–Ga anode materials was also discussed.