A novel class of organosulfur electrodes for energy storage

A broad class of organosulfur compounds is discussed which may offer unique advantages as positive storage electrodes in advanced battery systems. The organosulfur electrodes operate between ambient and 150/sup 0/C, are inexpensive, and inert to many metals. In addition, the physicochemical and electrochemical properties of the organosulfur electrodes may be varied in a predictable way. At room temperature these materials may be crystalline, liquid, or polymeric. Batteries based on the novel organosulfur positive electrodes and sodium metal negative electrodes have theoretical energy densities ranging from 350 to 600 Wh/kg. The system which has to data been studied in most detail is the sodium/tetra-ethylthiuram disulfide (TETD) couple which has a theoretical energy density of 360 Wh/kg and an open-circuit voltage of 2.3 V. Laboratory cells have been assembled and tested with maximum practical energy densities of over 110 Wh/kg at zero current drain and volumetric energy densities of 0.196 Wh/cm/sup 3/. These cells have been cycled between 10 and 90% of available capacity at power densities of 6 Wh/kg at an energy density of 80 Wh/kg and overall energy efficiency of 75%. Some experimental batteries delivered peak power densities of 40-60 W/kg for a period of a minute or more. Further, preliminary testing of batteries using simple alkyl disulfide electrodes have resulted in full charge/discharge cycles at current densities of 10 mAcm/sup 2/ at 105/sup 0/c.