Improved sodium sulfur LEO performance

Improved sodium sulfur technology has been developed for low Earth orbit (LEO) space applications. In addition to a high charge/discharge rate capability, improvements have been made relative to sodium availability, cathode corrosion resistance, cell resistance, and electrolyte performance. Cell sizes ranging from 10-Ah capacity to 55-Ah have been built and tested with the 55-Ah cell being utilized as a standard. A long cycle life of 10000 cycles without capacity loss has been demonstrated. The design is such that 60% and 80% depth of discharge are attainable at LEO rates and a specific energy of 186 Wh/kghas been demonstrated. A limited number of safety tests have been conducted on the final designed cells. These test have been successful in that no catastrophic failures have occurred