Discharge behavior of Mg–4wt%Ga–2wt%Hg alloy as anode for seawater activated battery

Magnesium–gallium–mercury alloy is one of the new developed anode materials for seawater activated batteries. The potentiodynamic polarization, galvanostatic discharge and electrochemical impedance spectroscopy of Mg–4%Ga–2%Hg alloy in seawater are studied and compared with commercial AZ31 and AP65 alloys in this study. The results show that Mg–4%Ga–2%Hg alloy exhibits different discharge behaviors in as-cast, homogenizing, rolling and annealing conditions. The annealing Mg–4%Ga–2%Hg sheet obtains the most negative corrosion potentials in different current densities. And the Mg–4%Ga–2%Hg alloy provides more negative corrosion potentials than AZ31 and AP65 alloys. EIS studies reveal that the Mg–Ga–Hg alloy/seawater interfacial process is determined by an activation-controlled reaction. The Mg3Hg and Mg21Ga5Hg3 phases improve the electrochemical properties of Mg–4%Ga–2%Hg alloy. The assembled prototype battery with Mg–4%Ga–2%Hg alloy as anode and CuCl as cathodes exhibits a satisfactory discharge performance because of the advantages in discharge characterizations and microstructure of the Mg–4%Ga–2%Hg alloy.