Quantifying the Role of the Grid in the Lead-Acid Battery: Part I. Towards a Design Model

Abstract In this paper, effect of coupling of the grid and the active mass on the electrode of the lead-acid battery is studied using a 2D model. The actual grid with crosshatch ribs is approximated with unidirectional parallel ribs to facilitate a reduction in dimensionality of the system to 2D. The model is based on porous electrode theory. The model is used to simulate the LAB system in different configurations of the ribs. The model predictions for potential drops associated with the flow of ionic and electric currents, activation overpotentials and equilibrium potentials at electrodes are analyzed. The predictions suggest that the IR drop due to the flow of electric current along the height of the electrode controls the overall battery discharge characteristics if a sufficient number of ribs is not used. The insufficient number of ribs leads to localized loss of electrode conductivity, resulting in reduced battery discharge capacity, whereas their critical minimum number delivers its full capacity. Finally, based on the predictions, a first-hand design equation is derived that can be used to design the grid to limit the electric potential drop in the battery as desired.