Achieving high power density and stability in aqueous Mg–air batteries using taurine electrolyte additives†

Abstract

Aqueous Mg–air batteries are promising candidates for large-scale energy storage, but their practical application is significantly hindered by water-induced parasitic reactions and the chunk effect. In this study, taurine (Tau) is an effective electrolyte additive for aqueous Mg–air batteries utilizing various magnesium anodes. The non-sacrificial Tau molecules, possessing both donor and acceptor groups, disrupt the inherent hydrogen bond network of H₂O and replace solvated H₂O in the Mg²⁺ solvation sheath, forming dynamic adsorption on Mg and creating a hydrophobic electric double layer. Consequently, taurine inhibits H₂O attack on Mg, promoting uniform Mg stripping. An appropriate amount of Tau not only enhances the discharge activity of the AZ31 anode but also suppresses its self-discharge phenomenon, achieving a surprising effect of simultaneously boosting voltage and anode utilization. Therefore, 0.2 M Tau was identified as the optimal electrolyte concentration and successfully incorporated in Mg–air batteries utilizing various routine Mg anodes (such as VW83, VW103, and LA103Z). The results demonstrate that Tau effectively enhances the discharge properties for Mg–air batteries employing various magnesium anodes.