Positive tubular plates of the lead–acid battery: General analysis of the discharge process

A general analysis of the discharge process in stationary positive tubular plates of lead–acid batteries is described. In the experimental part, the influence of the rate of discharge and the sulfuric acid concentration on the potential/time (E/t) discharge curves, the variation of specific capacity and the plate resistance during the discharge transient was studied. The potential/time curves show the general pattern. The capacity is related to the complete discharge process and the plate resistance to the conditions in the transient plateau region of the potential/time curves. On this basis, it is shown that the tubular positive discharge behavior can be interpreted with a zone reaction model involving three steps. The first corresponds to the solid-state reaction from PbO2 to PbO, with passage of current; the second, when the current effectively moved to a deeper surface zone of the pore in the plate, to the chemical reaction between the PbO and H2SO4 giving fundamentally disrupted PbSO4, and the third, to a recrystallization of the disrupted PbSO4. With the help of this model, the effect of the depletion of H2SO4 in the macropores is also analyzed. All the results are interpreted on the basis of the model.