Porous microspheres as additives in lead–acid batteries

The theoretical specific energy of the lead/acid battery is 176 W h kg−1. The specific energy actually achieved depends on the discharge rate but is typically only about 15–25% of this maximum value. The major reason for the lead acid battery's inability to obtain higher specific energies is that much of the active material in both the positive and negative electrode is not discharged. This is especially true at the higher discharge rates where the diffusion of sulfate ions into the positive plate limits the reaction. Porous, hollow, glass microspheres (PHGM) would allow for more electrolyte storage in the electrodes and enhance the high rate energy storage of lead acid batteries. In this paper, we present a method for making hollow, glass microspheres (HGMs) porous. Presently our process only produces small yields. We believe in the future that the yields with our process can be substantially increased. PHGMs could substantially improve the high rate performance of lead acid batteries and make these batteries more attractive for hybrid electric vehicle applications.