Effect of the electrode parameters on the behavior of a lead-acid cell during discharge, rest, and charge

Abstract

The performance of a lead-acid cell during discharge, rest, and charge is investigated by developing a mathematical model. The approach presented here is based on the macroscopic homogeneous model and takes the dissolution-precipitation mechanism in the negative electrode into account. The model is used to compare the experimental data with theoretically predicted values during discharge of a flooded lead-acid cell. The effect of the dissolution of lead, the diffusion of lead ions and the precipitation of lead sulfate crystals is not even neglected in low current discharge and is increased with the discharge current. As the discharge current increases, the active material in the outermost layer of the electrode becomes more deactivated at a low degree of discharge. The behavior of the positive electrode controls the cell performance for high current discharge. Ohmic loss is smaller in the negative electrode than in the positive electrode, which is owing to the higher conductivity of the negative active material. The charge characteristics of a lead-acid cell are observed by using numerical simulation. We investigated the effect of various parameters, such as concentration exponent of charge reaction, morphology parameter and limiting current density on the cell voltage during charge by including the dissolution-precipitation mechanism of the negative electrode. The limiting current density affects significantly the initial voltage rise, while it has only a very little influence on the concentration gradient in the cell, when the charging current density is constant. As charging the battery at high rates, the charging efficiency is lower due to the concentration polarization and the voltage rise at the beginning stages of charge. The cell behavior is numerically investigated for quick charging of a lead-acid cell under constant current or pulsed current. By incorporating the rest period and the depolarization pulse at high rate charge, we avoid the deterioration...