Studies on magnesium and its alloys in battery electrolytes

Abstract

Studies on the anode efficiency of magnesium and its alloys in battery electrolytes such as magnesium perchlorate, magnesium bromide, and magnesium chloride solutions were made by galvanostatic polarisation and corrosion rate measurements. The open circuit potential and corrosion rate of magnesium increase when lead is present in the alloy. The corrosion rates were observed to follow the order Mg> AP65 (Mg−(6·0−7·0) Al−(4·4−S·0)Pb) > AZ61(Mg−(5·8−7·2)Al−(0·5−1·5)Zn) > AZ31(Mg−(2·5−3·5)Al−(0·6−1·4)Zn) in all three electrolytes. Anode efficiency increased with increasing current density up to 40 mA cm⁻², but decreased above this level. Galvanostatic polarisation results indicated that corrosion of magnesium and its alloys in these electrolytes occurs under cathodic control. Of the tested alloys, AZ31 and AZ61 were found to be most suitable in respect of corrosion rate and anode efficiency in 2M Mg(ClO₄)₂ solution.