Electro Chemical Holdings Societe Anonyme

Programme 3 Patent Holdings

Aabh Patent Holdings Societe Anonyme

Isak L Vlok

Johan Coetzer

The invention provides a high temperature rechargeable electrochemical power storage cell a method of operating such cell, a cathode for the cell and a method of making the cell. A solid electrolyte sodium ion conductor separates a cell housing into anode and cathode compartments respectively containing molten sodium anode material and a nickel-containing active anode material. The active cathode material is dispersed in a porous matrix which is electronically conductive and has a sodium aluminium halide molten salt electrolyte, containing sodium and chlorine ions, impregnated therein. The cathode compartment contains an additional metal selected from iron, cobalt, antimony and mixtures thereof. The molten salt electrolyte has, dissolved therein, sodium iodide, which forms 1-20% by mass of the sodium halide in the cathode compartment.

Electrochemical cell comprising a molten salt electrolyte containing

The invention provides an electrochemical cell, a cathode therefor and methods of making them. The cell is of the high temperature alkali metal/transition metal halide type, having a molten sodium anode, a nickel/nickel chloride cathode, an essentially sodium aluminium chloride molten salt electrolyte and a solid electrolyte sodium ion conducting separator which separates the sodium from the molten salt electrolyte. The nickel/nickel chloride is dispersed in solid form in a porous electronically conductive electrolyte-permeable matrix which is impregnated by the molten salt electrolyte, and antimony in finely divided solid form is mixed with the nickel/nickel chloride in the matrix. The mass ratio of antimony to the nickel in the nickel chloride in the cell in its fully charged state is 2:100-130:100.

Electrochemical cell

A high temperature rechargeable electrochemical power storage cell has a molten sodium anode separated by sodium ion-conducting solid electrolyte separator from a solid cathode comprising an electronically conductive electrolyte-permeable porous matrix. The matrix is impregnated with a molten salt electrolyte, and has solid active cathode material dispersed therein. The molten salt electrolyte comprises a substantially equimolar mixture of sodium chloride and aluminium chloride. The active cathode material comprises at least one transition metal selected from the group consisting of Fe, Ni, Cr, Co, Mn, Cu and Mo having, dispersed therein, at least one additive element selected from the group consisting of As, Bi, Sb, Se and Te. The atomic ratio of transition metal:additive element in the active cathode material is 99:1-30:70, the cell having a charged state in which the active cathode material is chlorinated. The invention also provides a method of making such cell.

A method of making an electrochemical cell comprises loading into a cathode compartment of a cell housing comprising also an anode compartment containing at the operating temperature of the cell and when the cell is in its charged state, a molten alkali metal, M, anode, the anode compartment being separated from the cathode compartment by a suitable separator, a molten salt electrolyte having the formula MAlHal.sub.4 wherein Hal is a halide other than Br; an active cathode substance which includes a transition metal T selected from the group comprising Fe, Ni, Co, Cr, Mn and mixtures thereof; an alkali metal halide MHal; and a minor proportion of MBr thereby to make an electrochemical cell precursor. The precursor is charged at a temperature at which the molten salt electrolyte and alkali metal M are molten, thereby to halogenate the active cathode substance, with alkali metal being produced and passing through the separator into the anode compartment.

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Verwoerdburg, South Africa

Isak L Vlok