Effects of La addition on the microstructure, corrosion behavior and discharge performance of the as-casted AP63 anodes for Mg–air batteries

The impacts of La additions on the microstructures, corrosion resistance and discharge performance of the as-cast Mg–6Al–3Pb (wt. %) anodes for Mg–air batteries were systematically investigated. The Mg–6Al–3Pb–xLa (x = 0, 0.5, 1 and 2 wt. %) alloys primarily consisted of α-Mg, β-Mg₁₇Al₁₂, Al₁₁La₃ and LaAl₃ phases. The results indicated that the addition of La could not only increase the volume fraction of the second phase, leading to the formation of Al₁₁La₃ and LaAl₃ phases, but also effectively promote grain refinement. In terms of discharge performance, the AP63–1La alloy exhibited a high steady discharge voltage of −1.71 V (vs. SCE) at 10 mA·cm⁻². Regarding corrosion behaviors, the corrosion resistance of the alloys initially decreased and then increased with increasing La content. Notably, the AP63–2La alloy demonstrated the best corrosion resistance, due to the high proportion of acicular second phase inhibiting the corrosion process.