Improved Discharge Performance of AZ72-0.05La Alloy Anode via Refining Mg[sub.17]Al[sub.12] Phase

The morphology of phases in magnesium alloys is vitally important for their performance. It is found that improved discharge performance is achieved in AZ72-0.05La alloy via a refining Mg[sub.17]Al[sub.12] phase by means of hot rolling. Before rolling, as-cast AZ72-0.05La alloy has a relatively coarse and strip-like Mg[sub.17]Al[sub.12] phase. After rolling, the Mg[sub.17]Al[sub.12] phase becomes much finer, showing a granulated shape. Due to the refinement of the Mg[sub.17]Al[sub.12] phase, the discharge voltage and energy density of an Mg-air battery with as-rolled AZ72-0.05La alloy as the anode increases by 6% and 3% under a discharge current density of 20 mA·cm[sup.−2] in a 3.5% NaCl solution, respectively. The corrosion rate of the as-rolled AZ72-0.05La alloy is slightly larger than the as-cast AZ72-0.05La alloy, but still much lower than as-cast AZ72 alloy. The as-rolled AZ72-0.05La alloy possesses a discharge voltage of 0.74 V and an energy density of 918 mWh·g[sup.−1] under a discharge current density of 20 mA·cm[sup.−2], and a relatively low corrosion rate of 0.51 mg·cm[sup.−2]·h[sup.−1], demonstrating good overall discharge performance. This work provides a method for improving the discharge performance of Mg-air batteries.