Electrochemical cell

Claim 1

A high temperature electrochemical power storage cell which comprises an anode compartment containing, at the operating temperature of the cell and when the cell is in its charged state, a molten alkali metal anode, and a cathode compartment containing, at said operating temperature and in said charged state, an alkali metal aluminium halide molten salt electrolyte which is also molten at the operating temperature of the cell, and having the formula MAlHal 4 , wherein M is the alkali metal of the anode and Hal is a halide, the cathode compartment containing in said charged state, also a cathode which comprises an electronically conductive electrolyte-permeable porous matrix which has dispersed therein an active cathode substance THal 2 in which Hal is the halide of the electrolyte and T is a transition metal selected from the group of transition metals consisting of Fe, Ni, Co, Cr, Mn and mixtures thereof, the matrix being impregnated with said molten electrolyte, and, separating the anode compartment from the electrolyte, a separator which comprises a solid conductor of the alkali metal of the anode, the matrix comprising the transition metal T of the active cathode substance in porous form and the cathode including, embedded in the matrix, a metallic current collector having a coating thereon which is chemically and electrochemically inert in the cell environment and is electronically conductive, the metal of the current collector being no more noble than any transition metal of the active cathode substance.

Claim 12

A method of reducing the increase of internal resistance, which arises from repeated charge/discharge cycling, of a high temperature rechargeable electrochemical cell comprising an anode compartment containing, at the operating temperature of the cell and when the cell is in its charged state, a molten alkali metal anode, and a cathode compartment containing, at said operating temperature and in said charged state, an alkali metal aluminium halide molten salt electrolyte which is also molten at the operating temperature of the cell, and having the formula MAlHal 4 , wherein M is the alkali metal of the anode and Hal is a halide, the cathode compartment containing, in said charged state, also a cathode which comprises an electronically conductive electrolyte-permeable porous matrix which has dispersed therein an active substance THal 2 in which Hal is the halide of the electrolyte and T is a transition metal selected from the group of transition metals consisting of Fe, Ni, Co, Cr, Mn and mixtures thereof, the matrix being impregnated with said molten electrolyte, and, separating the anode compartment from the electrolyte, a separator which comprises a solid conductor of the alkali metal of the anode, the matrix comprising the transition metal T of the active cathode substance in porous form, and the cathode including, embedded in the matrix, a metallic current collector of a metal which is no more noble than any transition metal of the active cathode substance, the method comprising the step of coating the current collector with a coating which is chemically and electrochemically inert in the cell environment and which is electronically conductive.

Claim 13

A method of reducing the increase of internal resistance, which arises from repeated charge/discharge cycling, of a high temperature rechargeable electrochemical cell comprising an anode compartment containing, at the operating temperature of the cell and when the cell is in its charged state, a molten alkali metal anode, and a cathode compartment containing, at said operating temperature and in said charged state, an alkali metal aluminium halide molten salt electrolyte which is also molten at the operating temperature of the cell, and having the formula MAlHal 4 , wherein M is the alkali metal of the anode and Hal is a halide, the cathode compartment containing, in said charged state, also a cathode which comprises an electronically conductive electrolyte-permeable porous matrix which has dispersed therein an active substance THal 2 in which Hal is the halide of the electrolyte and T is a transition metal selected from the group of transition metals consisting of Fe, Ni, Co, Cr, Mn and mixtures thereof, the matrix being impregnated with said molten electrolyte, and, separating the anode compartment from the electrolyte, a separator which comprises a solid conductor of the alkali metal of the anode, the matrix comprising the transition metal T of the active cathode substance in porous form, and the cathode including, embedded in the matrix, a metallic current collector of a metal which is no more noble than any transition metal of the active cathode substance, the method comprising the step of coating the current collector with a coating which is chemically and electrochemically inert in the cell environment and which is electronically conductive.