Effect of lanthanum, cerium and other elements on the electrochemical corrosion properties of Pb–Ca–Sn–Al alloy in lead–acid batteries

The effects of different additives including selenium, silver, ytterbium, lanthanum, and samarium with a dosage of 0.02 wt.% ± 0.005 wt.% on the electrochemical behavior of Pb–Ca–Sn–Al alloy have been studied in sulfuric acid solutions. The electrochemical properties were evaluated by linear potential sweep (LSV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Metallurgical microscope and scanning electron microscope (SEM) were employed to investigate the morphology-property relationships of the corrosion layer and corrosion section of Pb–Ca–Sn–Al alloys. It was found that the additives including Ag, La and Sm can to some extent refine the grain and regular grain boundary of Pb–Ca–Sn–Al alloy, which was confirmed by metallurgical microscope. The formation of a uniform and dense corrosion layer on the surface of these three alloys can effectively reduce the corrosion rate of the alloy. Furthermore, the growth of Pb (II) and PbO₂ in corrosion layer on Pb–Ca–Sn–Al alloy is remarkably inhibited by adding Ag, La, and Sm as determined by the results of CV, EIS, and SEM. These experimental facts indicate that adding Ag, La and Sm can improve the corrosion resistance of the alloy.