EFFECTS OF SULFUR ADDITIVE ON THE PERFORMANCE OF NA NICL(2) CELLS/

NiCl2 electrode in Na//beta''-alumina//NaAlCl4//NiCl2 high-temperature rechargeable cells undergoes a morphological change during charge/dis charge cycling, which results in a rapid capacity decline and prematur e cell failure. Addition of sulfur was reported to have prevented this morphological change and improved the cycle life of the cells signifi cantly. Our earlier, single electrode studies indicate that the sulfur additive also improves the kinetics of NiCl2. A detailed study on the effects of the sulfur additive on the performance of NiCl2 electrode is reported here. Different methods of NiCl2 electrode fabrication are examined to improve its charge efficiency. The sulfur content in the electrolyte is optimized based on the charge/discharge cycling and SEM micrographs. Other (non-sulfur) less corrosive additives, based on tr ansition metals are examined for alleviating the morphological change during cycling. A combination of the transition metal additives and su lfur is expected to have a synergistic beneficial effect on the cycle life of NiCl2 electrode.