NEGATIVE CORROSION OF LEAD-ANTIMONY ALLOYS IN LEAD-ACID-BATTERIES AT HIGH-TEMPERATURES

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