Investigating paste additives to improve the specific energy performance of lead-acid batteries

In this dissertation, the change in electrical conductivity of the active material in lead acid batteries that occur during discharge was investigated. This change in conductivity limits the maximum utilization that the active material in both electrodes can realize and therefore limits the performance of these batteries. Additives, both conductive and non-conductive having different aspect ratios were evaluated with a two-dimensional computer model to determine their effect on active material utilizations. It was found that the larger conductive particles are less effective than the smaller particles for improving active material utilization. However, as the aspect ratios for the smaller particles are increased, the conductive additives begin to bridge what would have been isolated areas and this process can increase utilization.; In order to better understand the electrical conductivity of electrodes, particularly those having additives, a three-dimensional (3-D) model was developed. The simulation results of this model were compared with those theoretical numbers predicted by the Percolation Theory (PT) and the Effective Medium Theory (EMT). The results of the model were very similar to those values predicted by these theories.; In addition to the above studies of active material conductivity, tests were performed on two experimental cells to determine cell capacity at different discharge rates. Computer simulations of these cells were compared with the test results. This work was the first part of a test program that will more carefully examine the use of additives in the electrodes of lead acid batteries. Alternative designs for the lead acid battery were also investigated. These designs included a 42 V battery for automotive applications. Some concepts developed for the 42 V battery were further refined and used in a battery design for the Joint Tactical Electric Vehicle (JTEV).