The role of Al2Ca and Al2(Sm,Ca,La) particles in the microstructures and electrochemical discharge performance of as-extruded Mg-3wt.%Al-1wt.%Zn-based alloys for primary Mg-air batteries

In this work, the role of Al2Ca and Al-2(Sm,Ca,La) particles in the microstructures and electrochemical discharge performance of the as-extruded Mg-3wt.%Al-1wt.%Zn-based alloys has been reported and discussed for the anode design of Mg-air batteries. The Al2Ca and Al-2(Sm,Ca,La) particles strongly refine the grains of the as-extruded AZ31 alloy from 9.1 +/- 4.1 mu m down to 5.1 +/- 3.3 mu m. The Al2Ca and Al-2(Sm,Ca,La) particles increase the outputting cell voltage and discharge capacity of the modified AZ31 alloy. The AZ31-Ca alloy exhibits the highest discharge capacity and anodic efficiency of 1153 mAh/g and 52.5%, respectively, at 10 mA/cm(2). The promoted discharge performance should be mainly attributed to the grain refinement (improving the corrosion resistance) and fine Al2Ca phase throughout the matrix (beneficial for uniform dissolution of Mg phase). Additional Al-2(Sm,Ca,La) cubic particles further stimulate the anodic kinetics and aggravate the local dissolution of Mg phase near around, resulting in the deterioration of discharge performance.