Effect of La Addition on the Microstructure and Properties of Al-Fe-Mn Alloys for Lithium Battery Current Collectors

Abstract

Good electrical conductivity, mechanical properties and electrochemical performance are required for aluminum alloys acting as cathode current collectors of lithium ion batteries (LIBs). The effect of La alloying on the microstructure, mechanical properties and the electrochemical performance of Al-Fe-Mn alloys were characterized by optical microscopy, X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, tensile test, conductivity test and Tafel polarization curve test. The experiment results showed that Al13Fe4 and Al6(Mn, Fe) precipitates tended to nucleate and grow along the grain boundaries. The addition of La to the Al-Fe-Mn alloy could help to refine grains and spheroidize secondary phases. These changes in microstructure could improve the tensile strength and elongation at room temperature and a high temperature of 125°C and enhance the corrosion resistance of the alloy. However, the spheroidized precipitates tended to aggregate in the alloy with 0.15 wt.% La and this uneven aggregation resulted in a decrease in tensile strength and elongation in comparison to the alloy with 0.1 wt.% La, which suggested an optimal La content for the Al-Fe-Mn alloy.