Effect of magnesium on discharge behavior of Al-Sn-Ca-Mg anodes for Al-air batteries

In alkaline electrolytes, Mg elements affect the electrochemical properties and corrosion behaviors of Al-Sn-Ca alloys have been conducted. The results demonstrate that Mg improves the polarization behavior and further increases the anodic activity of Ca-containing Al anodes. Solid solubility Mg in the matrix is oxidized to Mg2+ during discharge. These ions boost the number of anion vacancies in the Ca-containing product layer, which encourages the diffusion of ions on the anodic surface, improves anodic polarization behavior, and allows it to operate at high current densities. Meanwhile, the "dissolution-redeposition" process of Sn is accelerated by the defects created by Mg2+, raising the overpotential of Al anodes for hydrogen evolution. As a result, Mg plays a significant role in Ca-containing Al alloys as anodes.