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

Abstract 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 −CF 3 groups and forming an MgF 2 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.