Development of high-specific-energy batteries for electric vehicles. Progress report, February 1973--July 1973

A high-specific-energy lithium/sulfur battery having the performance characteristics required for powering pollutionfree automobiles is described. The cells currently under development have negative electrodes of molten lithium and positive electrodes of sulfur (plus an additive to reduce the sulfur vapor pressure) separated by a molten lithium halide-containing electrolyte. The operating temperature of the cells is about 400 deg C. The performance goals for a single cell include a capacity density of 0.4 A-hr/cm/sup 2/ at a current density of 0.1 A/cm/sup 2/, a peak power density of 1-2 W/cm/sup 2/, and a minimum cycle life of 1000 cycles. Cells with positive electrodes consisting of sulfurarsenic-carbon mixtures in graphite housings have achieved short-time peak power densities and capacity densities that meet or exceed the goals for a single cell. A capacity density of 0.1 A-hr/cm/sup 2/ has been sustained at a discharge current density of 0.1 A/cm/sup 2/l (1-V cutoff) for more than 500 hr and 100 cycles. Improvement in cell design is needed, however, to achieve higher sulfur utilization and longer cell lifetimes. (auth