CAPACITY PREDICTIONS FOR LEAD ACID BATTERY PLATES HAVING CONDUCTIVE ADDITIVES/

In this paper, we predict the capacity of positive plates having condu ctive particles mixed into its paste. Computer models previously repor ted are used to make these predictions. The models use a few physical parameters to predict capacity. The most important of these parameters is the critical volume fraction. This parameter provides the maximum amount of active material that can be discharged before the paste's co nductivity limits the reaction. We estimate the critical volume fracti on for plates containing different size conductive particles using the conductivity model. These results are then used in the capacity model to predict cell performance. Conductive particles improve low rate ca pacity and, on a per weight basis, can improve cell capacity at higher rates. The model predicts that the addition of 34% by volume of a con ductive particle 20 mu m in diameter will increase the capacity from 2 5 to over 60% of the stoichiometric capacity at 1 h rate. We compare t he predicted performance of plates with conductive particles to other plates having no additives or non-conductive additives. A number of co nductive particles were tested in an attempt to validate the model, bu t all proved to be unstable in the positive plate's oxidizing environm ent.