An eco-friendly electrolyte additive for high-power primary aqueous Mg-air batteries

The performance of aqueous Mg-air batteries is predominantly constrained by two factors: the high polarization effect caused by the adherence of surface passive film, and the low efficiency resulting from the self-corrosion reaction. In this study, we propose the use of glycine as an electrolyte additive in 3.5 wt% NaCl solution to enhance the practical application of commercial AZ31 magnesium alloys at high current densities. The AZ31 alloy in blank NaCl solution with 0.1 M Gly displays a high discharge voltage of 0.81 V, with an anodic efficiency of 64% and a peak power density of 48.6 mW cm at 60 mA cm, which is about 42% higher than that of AZ31 in blank electrolyte (33.2 mW cm) without Gly. Furthermore, we elucidate the working mechanism in NaCl solution containing the electrolyte additive during discharge through theoretical calculations and experimental analysis, which significantly enhances the discharge activity and accelerates the mass transfer process of the electrode. All results demonstrate that glycine is a valid electrolyte additive for improving the discharge performance of high-power Mg-air batteries based on commercial AZ31 alloy.