In Situ Interfacial Passivation in Aqueous Electrolyte for Mg‐Air Batteries with High Anode Utilization and Specific Capacity

Mg-air batteries are a promising new generation of batteries because they can operate in neutral electrolytes that are safe and nontoxic. However, the high corrosion and low utilization of Mg anodes in Mg-air batteries result in low specific capacity and severe self-discharge. In this study, an Mg(OTf)₂ -based aqueous electrolyte is developed, which addresses these issues by reducing the contact of the Mg anode with water molecules from the hydrophobic -CF₃ groups and forming an MgF₂ protective layer. The assembled Mg-air batteries exhibit specific capacities of up to 1920 mAh g^-1 _Mg (87.32 % utilization based on the Mg anode). In addition, the resting time of the corresponding Mg-air batteries was 123 times longer than that of Mg-air batteries with pure NaCl electrolytes under the same conditions.