NaBF₄-dimethyl sulfoxide/NaCl-H₂O biphasic electrolytes for magnesium–air batteries

Mg-air battery is a promising electrochemical system for high-energy–density, long storage application. However, its commercialization is hindered by the low anode utilization rate mainly caused by the serious hydrogen evolution reaction (HER) in traditional NaCl aqueous electrolyte. Herein, we report NaBF₄-dimethyl sulfoxide (DMSO)/NaCl-H₂O biphasic electrolytes to alleviate the anode HER corrosion by allowing anodic reaction to take place in organic solution DMSO while ensuring high cathode activity with applying cathode reaction to occur in NaCl-H₂O solution. The discharge results show that its utilization rate of AZ61 alloy in NaBF₄-DMSO/NaCl-H₂O biphasic electrolytes is increased to 67% at 1 mA cm⁻² which is 17% higher than in NaCl-H₂O single electrolyte, and the anode energy density is up to 2020 Wh kg⁻¹. In addition, even at 15 mA cm⁻², its discharge voltage is still up to 1.02 V which is higher than that in similar literatures using organic electrolytes for Mg anode.