Lilliwyte Societe Anonyme

Anthony A Meintjes

Keith T Adendorff

Johan Coetzer

Walter G Bugden

Roy C Galloway

A method of making an electrochemical cell comprises loading into the cathode compartment of a cell housing comprising an anode compartment separated from a cathode compartment by a separator which is a solid conductor of ions of alkali metal M or is a micromolecular sieve which contains alkali metal M sorbed therein; an alkali metal aluminium halide molten salt electrolyte having the formula MAlHal.sub.4 wherein M is the alkali metal of the anode and Hal is a halide; Cu as an active cathode substance; and an alkali metal halide MHal wherein M and Hal are respectively an alkali metal and a halide; 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 Cu, with alkali metal being produced and passing through the separator into the anode compartment, the proportions of alkali metal halide MHal, Cu and molten salt electrolyte loaded into the cathode compartment being selected so that when the cell is fully charged and all the available active cathode substance has been halogenated, the proportion of alkali metal ions and aluminium ions is such that the solubility of the active cathode substance in the molten electrolyte is at or near its minimum.

Electrochemical cell

A method of making an electrochemical cell comprises loading into a cathode compartment of a cell housing comprising an anode compartment separated from a cathode compartment by a separator which is a solid conductor of ions of alkali metal M or is a micromolecular sieve which contains alkali metal M sorbed therein, an alkali metal aluminium halide molten salt electrolyte having the formula MAlHal.sub.4 wherein M is the alkali metal of the separator and Hal is a halide; an alkali metal halide MHal wherein M and Hal are respectively an alkali metal and a halide; a transition metal T selected from the group comprising Fe, Ni, Co, Cr, Mn and mixtures thereof, as an active cathode substance; and a current collector comprising at least one of copper, a copper-based substance, and a copper-coated substance, 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 halogenating the active cathode substance, with alkali metal M being produced and passing through the separator into the anode compartment.

Electrochemical cells

The invention provides a cathode for an electrochemical cell, a cell incorporating the cathode, and a method of rendering the cathode resistant to a drop in capacity associated with cell cycling. The invention involves dispersing a transition metal, other than Ni, Fe, Cr, Co or Mn, in the active cathode substance, the cathode comprising an electronically conductive porous matrix impregnated with sodium aluminium halide molten salt electrolyte containing chloride ions. Said active cathode substance is an chlorinated nickel-containing substance dispersed in the matrix.

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Pretoria, South Africa

Anthony A Meintjes