Hypoeutectic Mg–Zn binary alloys as anode materials for magnesium-air batteries

Abstract

Zn is an eco-friendly element with high solid solubility (6.2 wt%) in Mg. In this research, four hypoeutectic Mg-xZn (x = 2, 4, 6, and 15 wt%) binary alloys are systematically investigated as anode materials for Magnesium-air (Mg-air) battery. The self-corrosion and battery discharge behavior of these four hypoeutectic Mg–Zn alloys are analyzed by electrochemical measurements and half-cell discharge tests. The results show that the addition of 2 wt% Zn significantly improves the anodic efficiency and specific capacity of Mg, while addition of 6 wt% and 15 wt% Zn reduces its discharge properties. It is due to the large volume fraction of Mg7Zn3 and Mg4Zn7 intermetallic phases act as cathode accelerating the self-corrosion of alloy anode. Mg-2 wt.% Zn alloy anode has the best battery performance with 54.42% utilization efficiency and 1185.50 mA h g−1 specific capacity at 10 mA cm−2, and has the highest specific energy density 1140.1 mW h g−1 at 2 mA cm−2.