Rechargeable High-Voltage Low-Temperature Molten-Salt Cell Na/ beta ''-Alumina/SCl sub 3+ in AlCl sub 3 -NaCl. Final Report

摘要

This report deals with the rechargeable molten salt cell: Na/ beta ''-alumina/SCl sub 3+ in AlCl sub 3 -NaCl, and its underlying chemistry. This cell is operated at 180 to 250 deg C, and is characterized by two discharge plateaus: 4Na + SCl sub 3 AlCl sub 4 + 3AlCl sub 3 = S + 4NaAlCl sub 4 and 2Na + S + AlCl sub 3 = AlSCl + 2NaCl. The AlCl sub 3 -NaCl melt is important in stabilizing several sulfur species formed in charge/discharge processes and in maintaining a conducting liquid positive mixture. The cell voltage in the fully charged state is greater than or equal to4.30 V for the first step and 2.75 V for the second step. The theoretical capacity is in excess of 190 Ah kg sup -1 , corresponding to a theoretical specific energy in excess of 700 Wh kg sup -1 , based on the electrode active materials. High energy and power densities have been achieved. Hundreds of deep charge/discharge cycles have been obtained for several cells using Reticulated Vitreous Carbon or tungsten positive current collectors. 61 refs., 7 figs., 4 tabs. (ERA citation 11:040701)