Behavior of lead electrodes in sulfuric acid solutions. II

An attempt was made to clarify the question whether the variation in the length of the "first discharge plateau" with change in H 2 SO 4 concentration was caused by a change in the efficiency of PbO 2 formation or by a variation in its discharge rate. The relationships between acid concentration, "passivation time", amount of PbSO 4 formed during passivation, and the quantity of PbO 2 derived therefrom during charging were investigated. The amount of PbSO 4 on the anode increased with a decrease in passivating acid concentration. More PbO 2 was formed at lower charging acid concentrations. The higher the discharge acid concentration, the greater was its stabilizing effect on PbO 2 discharge. The combination of two factors, i.e. a decrease of the amount of PbO 2 formed at higher acid concentrations together with an increase in the PbO 2 stability, gave rise to the maximum 10.5 N H 2 SO 4 .