An Energetic Medium for Electrochemical Storage Utilizing the High Aqueous Solubility of Potassium Polysulfide

The aqueous solubility of potassium polysulfide is measured to be 8.5m (64 % K.2S4, 36 % H20 by weight) at 25 ~ and 11.4m (70 % by weight) at 50 ~ This novel, energetic medium, containing more total sulfur than water, are investigated as high energy density half-cells for secondary electrochemical storage systems, according to K2S~+6e + 6K +~-4K2S The storage half-cell, contained by a sulfonated styrene and Teflon membrane, is demonstrated to be capable of being cy-cled at room temperature, with a storage capacity of up to 1.8 • l0 ~ C/kg, operating at currents of over 1A through a 10 cm ~ thin film CoS electrode with overpotential losses of less than 2 mV/cm2/mA. Economic and environmental factors and the contin-uing depletion of the earth's fossil fuels, have prompted a search for high energy density, low cost batteries for vehicular and peak power uses. Alkali sulfur batteries have been a candidate in this search. However, prob-lems, including those associated with the high operating temperatures necessary to maintain l iquid phase alkali