THE USE OF TETRAVALENT SULFUR IN MOLTEN CHLOROALUMINATE SECONDARY BATTERIES

A new rechargeable cell Na/Na** plus ion conductor/SCl//3** plus in molten AlCl//3-NaCl is described. This cell operates at temperatures in the range of 180 degree -250 degree C and has an open-circuit voltage of 4. 2V. The discharge process involves the reduction of tetravalent sulfur to the elemental state; sulfur can be further reduced to sulfide. The preferred sodium ion conductor is beta double prime -alumina. High energy density values, large percent utilization of the active material, and good energy efficiency have been demonstrated. The performance of cells prepared in the discharged and charged states were found to be the same. The number of deep charge/discharge cycles has exceeded 400. This study is applicable to electric vehicles.