Development of a circulating zinc-bromine battery, Phase II. Final report

This report summarizes Phase II of a multi-phase program aimed at developing Exxon's circulating zinc-bromine battery into an advanced energy storage system. Previous work at Exxon had developed a basic zinc-bromine battery system approach. This approach utilizes carbon-plastic electrodes in a bipolar stack design, a circulating electrolyte with separable bromine complexes, and shunt current protection. Phase II was highlighted by the successful scale-up and demonstration of a 20 kWh zinc-bromine battery module. Important technology improvements were demonstrated in the areas of extended life cycling, low cost stack technology, high power/high efficiency supported electrolytes, and system auxiliaries. The basic technology was augmented via increases in parametric testing, materials testing, and electrolyte studies. Production cost estimates from Phase I ($28/kWh in 1980$) were projected to an OEM price of $37/kWh using the A.D. Little costing method. A revised cost analysis, using an approach in which all battery components are produced at the battery manufacturing facility (as compared to the original analysis based on purchase of cell components from plastics fabricators) showed essentially the same factory costs as the original estimate (approx. $28/kWh). A design has been developed for a prototype 20 kWh energy storage system which will be delivered to Sandia Nationalmore » laboratories in 1983 near the completion of Phase III. Project effort is continuing to show steady progress toward the attainment of this goal.« less