A study of the discharge characteristics of lead—acid batteries

A theoretical analysis of the electrolyte concentration distribution and current distribution in the porous lead dioxide electrode has been made by application of Fick's second law which was combined with approximate mass balances. The macrohomogeneous model for porous electrodes was used. The parameters in the models were determined experimentally for the lead dioxide battery plates and the special experimental cylindrical electrodes investigated. Numerical solutions for special cases are discussed. Theoretical results are in good agreement with experimental determinations. According to laser interferometry analysis the assumption of convectionless diffusion is, in practice, a good approximation in most cases.Theoretical studies of the local overpotential show that the utilizable capacity is determined by the decreasing ionic concentration of the electrolyte because the electrode reaction takes place mainly in the outer layers of the electrode, if the discharge current has a high value, e.g., full discharge time is less than 10 min.