Enhancement of the discharge performance of Al-0.5Mg-0.1Sn-0.05Ga (wt.%) anode for Al-air battery by directional solidification technique and subsequent rolling process

The corrosion behavior and discharge characteristics of Al-0.5Mg-0.1Sn-0.05Ga (wt.%) alloys with different grain sizes in 4 M NaOH solution were investigated by collecting hydrogen, electrochemical measurement, discharge test, and microstructure analysis. The results reveal that the coarse-grained microstructure has a lower corrosion rate than the fine-grained one. As the annealing temperature increases, the grain size becomes larger, and more Sn-rich phases are solid-dissolved into the matrix, which results in less hydrogen evolution corrosion. The coarse-grained sample (6532 mu m) produced by the directional solidification technique in combination with the rolling process and subsequent annealing at 600 degrees C has outstanding discharge performance. Its peak energy density reaches approximately 3743.9 Wh.kg(-1) (at 40 mA cm(-2)), which exceeds the reported Al-Mg-Sn-In/Bi, Al-Mg-Ga-Sn-In, Al-Zn-In, Al-Bi-Pb-Ga, and Al-Sn/In/Ga anodes. Also, the anode efficiency and peak energy density of the sample at 40 mA cm(-2) is 23.4% and 33.2% higher than that of the as-cast ones, respectively. (C) 2020 Elsevier B.V. All rights reserved.