Electrochemical performance of pure Al, Al-Sn, Al-Mg and Al-Mg-Sn anodes for Al-air batteries

In this work, pure Al, Al-Sn, Al-Mg, and Al-Mg-Sn alloys have been investigated as anodes for aluminum-air batteries. Effects of Mg and Sn additions on the aluminum anodes for Al-air battery in 4 mol L-1 KOH solution have been evaluated by self-corrosion test, open circuit potential, potentiodynamic polarization, electrochemical impedance spectroscopy, cell voltage and galvanostatic discharge as well as ab-initio energy calculation based on density functional theory. The results show that Al alloy anodes show better corrosion resistance and battery performance than the pure Al anodes. The self-corrosion rate of Al alloys increase in the following order: Al > Al-Sn > Al-Mg-Sn > Al-Mg. The Al-Mg alloy shows the smallest self-corrosion rate and largest capacity among the three Al alloy anodes. The Al-Mg-Sn alloy has the best electrochemical performance and battery discharge performance. SEM, EDS and 3D measuring laser microscope analysis of Al alloys are in good agreement with the self-corrosion test and electrochemical characteristics. Furthermore, the ab-initio energy calculation also reveals the positive role of alloying elements in enhancing corrosion and electrochemical performances. (C) 2019 Elsevier B.V. All rights reserved.