Performance Improvement of Underwater Mg-Oxygen Battery with Parameter Optimization

Mg-air battery is a promising candidate as power supply because of high specific energy, stable discharge voltage, long storage life and friendly environment. However, the corrosion and passivation of Mg remains unresolved as well as oxygen supply, resulting in increase of electrode overpotential. Here, a type of oxygen electrode is present for Mg-oxygen battery, where hydrogen peroxide can directly and indirectly form hydroxide ions by means of nickel foam sandwiched with MnO2 and Fe/C. In optimization of electrolyte concentration, inhibitor and electrode structure, Na3VO4 is superior to Na3PO4 and La(CH3COO)3 inhibiting Mg corrosion, the optimal NaCl concentration is obtained for Mg-air battery, and the oxygen electrode can effectively improve the performance of Mg-oxygen battery. The results show that the Mg-oxygen battery employing 0.3 wt.% H2O2 as oxygen supply and 15.5 wt.% NaCl as the electrolyte can stably run for more than 7 h, and the battery is discharged above 1 V at the current density of 25 mA cm−2. The findings of Mg-oxygen battery can be available for power supply in the anaerobic or anoxic environment.