Effect of microstructure evolution on the discharge characteristics of Al-Mg-Sn-based anodes for Al-air batteries

In this study, the microstructure of Al-0.5Mg-0.1Sn alloys is controlled by rolling deformation and subsequent annealing process, and its influence on electrochemical performance and discharge behaviour is discussed. The results show that the grain boundaries in the low-temperature annealed (<300 degrees C) alloy are mainly low-angle grain boundaries (LAGBs), which improves the corrosion resistance of the alloy and also provides more active sites for the discharge reaction. When the annealing temperature exceeds 300 degrees C, the proportion of high-angle grain boundaries (HAGBs) in the alloy gradually increases. These HAGBs serve as reaction channels and are accompanied by more hydrogen release, which is not conducive to anode efficiency. Furthermore, the 200 degrees C annealed alloy have the best corrosion resistance and discharge performance. Its peak energy density reaches 4080.5 mWh.g(-1) at 20 mA cm(-2), which is 15.71% higher than its as-cast one. At 40 mA cm(-2), its anode efficiency is as high as 98.69%, and the corresponding specific capacity is about 2941 mAh.g(-1).