Performance of fine structured aluminum anodes in neutral and alkaline electrolytes for Al-air batteries

Aluminum (Al) is an innovative anode material for metal-air batteries. But high corrosion rates and large polarization interfere with its commercial application. In the study reported in this paper, an ultrafine-grained (UFG) aluminum anode was prepared by equal channel angular pressing (ECAP) at room temperature. The electrochemical properties of the Al anode were investigated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization in 4 mol L−1 NaOH, KOH and 2 mol L−1 NaCl. Battery performance using the anodes was tested by constant current discharge at 10 mA cm−2 in the referenced electrolytes. The experimental results showed that finer grain sizes enhance battery performance in alkaline electrolytes, due to active dissolution of the Al anode. But in the NaCl electrolyte, the fine grain size of the Al anode offers no performance due to the blockage of the oxide film and local corrosion. This anode fabrication approach provides a means for improving the performance Al-air battery in alkaline electrolytes.