Electrochemical performance of Mg-air batteries based on AZ series magnesium alloys

The purpose of this study is to select a common commercial Mg alloy to function as an anode for Mg-air batteries, with low anode passivation and minimal hydrogen evolution-induced corrosion being desirable characteristics. Corrosion and discharge performance of 3N5 Mg, AZ31, AZ61, and AZ91 alloys was studied. Corrosion susceptibility decreases and anode utilization factor gradually increases with Al content for the 3N5 Mg, AZ31, and AZ61 alloys. The key factors for these results are associated with the Mg17Al12 phase, which can act as a barrier to prevent the self-peeling of discharge products. For the AZ91 alloy, the addition of about 9wt% Al drastically increases discharge activation. Electrochemical impedance spectroscopy and scanning electron microscopy support the results of electrochemical and discharge performance tests. Therefore, AZ61 alloy is the best-suited anode material for the Mg-air batteries in the 0.6M NaCl electrolyte.