Hydrogen Evolution Behavior of Dissolving Magnesium Investigated By EIS and Gas Chromatography

Abstract

An air battery is expected as a power source for the automobile and disaster battery because it has a high energy density and charge voltage. Since the magnesium is the less noble material, it is expected as a negative electrode active material of air battery. It is well known that the cathodic reaction of hydrogen evolution was occurred at magnesium surface during anodic polarization measurement of magnesium (1). Petty et. al (1) suggested that the fraction of dissolving magnesium enters the solution as univalent magnesium (Mg+), where it is oxidized by water. Samaniego et. al (2) reproduced the experiment performed by Petty et. al (1) and supplemented with modern in situ Raman spectroscopy. They concluded that the existence of univalent magnesium was not established by Petty et. al (1). Frankel et. al (3) suggested that the ability of magnesium to support the cathodic reaction is enhanced during the anodic dissolution as the result of an increase on the exchange current density for the hydrogen reaction. Although the mechanisms of hydrogen evolution on the magnesium surface have been suggested, reactions of the hydrogen evolution have not been clarified in detail yet. In this study, the relation between the anodic dissolution of magnesium and the hydrogen evolution occurred during anodic polarization of magnesium is investigated by the simultaneous measurements of electrochemical measurement and gas chromatography. The hydrogen evolution of the dissolving magnesium was examined by the 3D impedance measurement in 0.5 M NaCl. The amount of the hydrogen gas during anodic polarization of magnesium was detected by the gas chromatography.