in particular embodiment of the inv

in particular embodiment of the invention the compound is sodium aluminium chloride according to the formula NaAlCl4,the alkali metal halide being sodium chloride,the molten alkali metal being sodium,and the separator being beta-alumina,with the cell operating at a temperature sufficient to melt the NaAlCl4,eg at least 165,and the electrical potential applied by the external circuit being above the formation potential of AlCl3 according to reaction(1)above,ie at least 1.8 volts.in this embodiment,the terminal of the external circuit in contact with the NaAlCl4 may be a consumable aluminum bar or rod,the other terminal may be a stainless steel or aluminum rod and sodium chloride in particulate form may be added to be the NaAlCl4 at the average replaced when necessary.the molten sodium will be tapped off as it is produced and so will the NaAlCl4 produced,conveniently through a porous filter,the filter and the size of the NaCl particles employed being selected such that the paricles or at least undesirably large particles do not pass the filter.