Anticorrosion and discharge performance of calcium and neodymium co-doped AZ61 alloy anodes for Mg-air batteries

Calcium (Ca) and neodymium (Nd) were introduced in the AZ61 alloy as alloying elements. The microstructure, corrosion behavior, and discharge properties of AZ61-1Nd-xCa (x = 0, 0.5, 1, 2 wt.%) alloys as anodes for Mg-air batteries were systematically investigated. The results indicated that the AZ61-1Nd-1Ca alloy exhibits the best corrosion resistance during electrochemical experiments and hydrogen evolution tests. Discharge performance tests showed that the AZ61-1Nd-1Ca alloy exhibits the best specific capacity (1193.6 mAh g−1), energy density (1893.7 mWh g−1), anode efficiency (60.3%), and cell voltage (1.246 V) at higher current densities. This is mainly attributed to the addition of Ca element, which refines the grain size of the alloy and increases the grain boundary area. In addition, Al2Nd and Al2Ca phases have similar corrosion mechanisms in the cross-section of the extruded alloy. The precipitated granular Al2Ca phase is uniformly dispersed on the substrate and acts as a physical barrier. This not only enhances the corrosion resistance of the alloy but also improves the anode efficiency of the alloy during discharge.