Influence of homogenization treatment on corrosion behavior and discharge performance of the Mg–2Zn–1Ca anodes for primary Mg-air batteries

Abstract

The corrosion behavior and discharge performance of Mg–2Zn–1Ca alloy, used as the anodes for primary Mg-air batteries and carried out with different homogenization treatments (HTs), are investigated by electrochemical and battery tests. After HT, the proportion of the second phase in the alloy decreases, and the grain size increases, which reduces the self-corrosion rate of the alloy. HT2 (homogenization treatment at 440 °C for 24 h) alloy has the lowest corrosion rate at 0.07 mm/year, which is approximately 1/3 of that of as-cast alloy. The discharge performance of HT2 anode is the best in all experimental alloys (HT1, HT2 and HT3 alloys obtained by homogenizing at 420 °C, 440 °C and 460 °C for 24 h, and as-cast Mg–2Zn–1Ca alloy). At 10 mA cm−2, the anode efficiency and discharge capacity are 68.87% and 1477.10 mAhg−1, respectively, which are 14.51% and 26.59% higher than those of the as-cast alloy. This is due to the dissolution of the second phases in the Mg matrix, which effectively increases the contact between the electrolyte and the Mg matrix, and makes the discharge products fall off easily. At the same time, the dissolution mechanism of Mg–2Zn–1Ca alloy in the discharge process is proposed.