Exploring the effect of sodium salt of Ethylenediaminetetraacetic acid as an electrolyte additive on electrochemical behavior of a commercially pure Mg in primary Mg-air batteries

Abstract

In this study, sodium salt of Ethylendiaminetetraacetic acid (EDTA), a strong and widely-used complexing agent, was utilized as an additive for a primary Mg-air battery electrolyte with a commercially pure magnesium anode. The electrolyte pH (ranged 7.0 to 11.0) was taken as the main parameter to explore the effect of EDTA on the discharge performance of the Mg anode. The results show that the most negative half-cell discharge potential of the Mg anode is achieved in the slightly alkaline pH around 9, at which the EDTA has the strongest ability to prevent the formation of fouling Mg(OH)2 and improve the anode activity. The utilization efficiency of the discharged Mg anode is enhanced with the increase in pH of the electrolyte due to several mechanisms, including suppressing the chunk effect, weakening the detrimental Negative Difference Effect (NDE), and promoting the formation of a more protective layer on the Mg anode surface.