The influence of samarium (Sm) on the discharge and electrochemical behaviors of the magnesium alloy AZ80 as an anode for the Mg-air battery

The influence of Sm on the microstructure, electrochemical properties, and discharge performance of cast AZ80 as the anode for Mg-air battery are investigated. AZ80 containing Sm has refined α-Mg grains and contains the Al2Sm phase. With increasing Sm content, the number and size of the Mg17Al12 phase particles are reduced. The AZ80-xSm anodes have higher electrochemical activity and lower self-corrosion rates than AZ80. The AZ80-xSm anodes also have a high discharge performance and a stable discharge voltage, which is attributed to the refined structure and Al2Sm particles. The AZ80-3Sm anode has the best discharge capacity of 1439 mAh g−1 and the best anode efficiency of 65% at 40 mA cm−2, which are 17% and 20% higher than for the AZ80 anode. This anode has an output peak energy of 1719 mWh g−1 at both 10 and 20 mA cm−2, compared with 1510 mWh g−1 for AZ80 at only 20 mA cm−2. The AZ80-xSm anodes have smoother discharge surface morphology, which is beneficial to the exfoliation of discharge products.