Enhancement of discharge performance for aqueous Mg-air batteries in 2,6-dihydroxybenzoate-containing electrolyte

In this work, 2,6-dihydroxytbenzoate (2,6-DHB) is evaluated as an efficient electrolyte additive for aqueous Mg air batteries based on diverse metallic Mg anodes. EIS measurements amid intermittent discharge and real-time hydrogen evolution measurements during discharge were applied to clarify the effective mechanism. The dependence of working mechanism on 2,6-DHB concentration was investigated for a newly developed Mg0.15Ca anode. The results reveal that sufficient amount of 2,6-DHB simultaneously improves the discharge activity and inhibits the self-discharge of Mg-0.15Ca anode, leading to negative average potential and high anodic utilization efficiency. Accordingly, 0.2 M 2,6-DHB is determined as the most suitable electrolyte concentration and applied during Mg-air battery tests based on diverse commercial Mg anodes (pure Mg, Mg-0.15Ca, AZ31 and AM50). The results demonstrate that 2,6-DHB efficiently improves the discharge performance of Mg-air batteries with different Mg anodes.