Effects of cobalt in lead/acid batteries

The effects of cobalt additions (0.1–1 g/1) to the electrolyte have been studied by anodic corrosion tests on sheets of various alloys, and by continuous charge, cycling and charge retention tests on thick plate automotive-type of batteries. Positive grid corrosion decreases with increase in cobalt concentration but the effect is less marked for alloys with high intrinsic corrosion resistance. Cobalt oxidizes some types of separator even at a relatively low concentration. The top-of-charge voltage is reduced by the presence of cobalt, the effect occurring mainly at the positive plate. Cobalt causes increased open-circuit losses but the effect is fairly small at low concentrations (0.1–0.15 g/1).