Effect of calcium addition on microstructure, corrosion behavior, and discharge performance of Mg −6Al-1Sn-0.35%Mn alloys as anodes for primary Mg-air batteries

The effect of varying Calcium additions (0, 0.5, 1, 2, and 3 wt%) on the electrochemical corrosion and discharge performance of as-cast Mg-6Al-1Sn-0.35Mn (ATM610) alloys as anodes for primary Mg-air batteries was systematically investigated. Due to the formation and uniform distribution of the secondary phases such as Mg 2 Ca, the corrosion resistance initially improved with moderate Ca addition and then deteriorated at higher concentrations. Electrochemical measurements demonstrated that the alloy containing 1 wt%Ca exhibited the lowest corrosion current density (I corr ) of 3.7 × 10 −5 A/cm², indicating an optimal protective surface film and reduced micro-galvanic corrosion. Furthermore, under galvanostatic discharge conditions at 10 mA cm −2 , the 2 wt% Ca added alloy demonstrated the highest discharge activity, delivering a peak specific capacity of 1751.0 mA h g −1 and an anodic efficiency of 79.71%. The results suggest that microstructural modification via controlled Ca addition effectively balances the trade-off between self-corrosion mitigation and anodic dissolution kinetics, making these tailored alloys highly promising anode materials for aqueous Mg-air battery applications.