Construction of a Corrosion-Resistant Film on the Surface of a Magnesium Alloy Anode and Its Discharge Performance for Primary Battery

Magnesium metal anodes have great application prospects in the field of electrochemical energy storage. However, the high corrosion rate and surface passivation in aqueous electrolyte seriously limit the discharge performance of magnesium primary batteries. Herein, a phytic acid/magnesium fluoride composite corrosion-resistant protective layer is constructed in situ on the surface of the AZ31B magnesium alloy through the synergistic reaction of phytic acid and potassium fluoride. The electrochemical test shows that the composite layer can significantly inhibit the corrosion of the magnesium anode, the corrosion current density is reduced from 1.04 × 10 –4 A cm –2 to 1.30 × 10 –5 A cm –2, and the kinetics of hydrogen evolution is obviously slowed down. The specific discharge capacity of the modified AZ31B anode/MnO 2 full cell reaches 1997 mAh g –1 at a constant current of 50 mA g –1, which was about 2.5 times higher than that of the cell used for the untreated AZ31B anode (799 mAh g –1 ). The mechanism analysis confirms that the composite film cooperates with the chemical stability of the interface through the physical barrier, effectively inhibits the formation of passive film, and promotes the diffusion of Mg 2+, thus significantly improving the utilization rate of the anode and the discharge efficiency of the full cell. This study provides an engineering surface protection scheme for developing high-performance, environmentally friendly magnesium batteries.