Galvanic alkali metal chloride cells with melting electrolytes, batteries from these cells and processes for their protection

摘要

The invention provides a method of protecting an electrochemical cell which has a molten sodium anode, a chloride-ion containing sodium aluminum halide molten salt electrolyte, an iron-containing cathode in contact with the electrolyte and a solid conductor of sodium ions which separates the anode from the electrolyte, from the adverse effects of overcharging. The method comprises operating the cell, to prevent oxidation of iron to FeCl3 in the cathode, by connecting it in parallel with a protective cell having an open circuit charging plateau at a voltage less than the open circuit voltage of the Fe/FeCl3//Na plateau of the cell being protected, and greater than the open circuit voltage, in its fully charged state, of the cell being protected. The invention also provides a cell of this type protected in this fashion, a battery including one or more such protected cells, and a cathode for such cells.