Negative corrosion of lead-antimony alloys in lead-acid batteries at high temperatures

When lead-acid batteries are used at high temperatures, corrosion is sometimes observed in negative components made of lead-antimony alloys. This corrosion seems to be caused by the antimony contained in lead alloys. We examined the effects of temperature, the concentration of sulfuric acid, and the configuration of test specimens on negative electrode corrosion. We also explored the mechanism by which negative component corrosion occurs when using lead-antimony alloys. Specimens in the electrolyte were not corroded at all, but portions just above electrolyte level and inside tiny spaces were corroded. The reason for this corrosion seems to be as follows. Corroded areas are covered with an electrolyte film that has a high resistance, so they cannot be polarized to the full cathodic protection potential. However, as lead-antimony alloys have a dendritic microstructure, with metallic antimony dispersed throughout the lead phase, local cell reactions between Sb and Pb occur in corroding areas, resulting in the evolution of hydrogen gas and the formation of lead sulfate.