Modeling and verifying the performance of lead/acid battery cells with paste additives

This dissertation focused on understanding the capacity performance limiting mechanisms of the lead-acid battery. To develop this understanding, the two primary capacity limiting mechanisms, diffusion of the electrolyte and electrical conductivity of the active mass, were modeled. The model, correspondingly, has two parts. The first part of the model predicts the diffusion of the electrolyte within the battery, both between the positive and negative plates, and within the active mass of the positive plate. The second part of the model predicts how much of the positive active mass reacts based on Metzendorf's critical volume fraction hypothesis.; After the model was developed, standard plates, containing no additives were used to verify the accuracy of the model. Next, the model was used to predict the behavior of plates that contained hollow borosilicate glass microspheres. It was found that these particles increased positive plate performance at high discharge rates because a higher percentage of positive active mass reacted. The glass microspheres, however, were found to decrease the critical volume fraction and thereby decrease the low rate discharge capacity. To counter this effect, conductive particles were considered as a replacement for the microspheres and modeled. The model predicts that a conductive particle, 20-50 {dollar}mu{dollar}m in diameter, and added in a ratio of 34% by volume, will improve the performance for any discharge rate. To date, these predictions have not been verified because no conductive material has been found that can withstand the high anodic potential of the positive plate.