Role of minor alloying elements on the performance of lead/acid battery grids. Part 2. Corrosion of lead-arsenic alloys

Corrosion of Pb---As alloys (As = 0.1, 0.2, 0.3 and 0.4%) in 5.0 M H2SO4 solutions at 30°C was studied under open-circuit, potentiostatic and galvanostatic polarization conditions. The sulfation process under open-circuit conditions increased as the As concentration increased and the open-circuit potential shifted to more cathodic values. The presence of As affected significantly the potentiostatic polarization curve and caused a substantial decrease in passivity current and increased the overpotentials of both the O2- and the H2-evolution reactions. The self-discharging process decreased as the concentration of As increased with formation of substantial amounts of lead oxide beside PbSO4. When Pb---As alloys were subjected to alternative cathodic and anodic galvanostatic polarization cycles, the corrodable layer thickness increased in the order of: Pb-0.1%As>Pb-0.3%As%>Pb-0.4%As>Pb>Pb-0.2%As. The efficiency of PbO2 formation also depended on the percentage As.