High temperature electrochemical cell with molten alkali metal anode
AssigneeElectro Chemical Holdings Societe Anonyme
InventorJohan Coetzer
Life of this patent
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Abstract
An electrochemical cell comprises a housing defining an interior space, and a separator in the housing dividing said space into an anode compartment and a cathode compartment. A sodium anode is in the anode compartment, a cathode being in the cathode compartment, electrochemically coupled by the separator to the anode. The anode is molten, the separator being a conductor of sodium cations and comprising at least 5 tubes having open and closed ends, the cathode being in the tubes and each tube communicating with a header space in an electronically insulating header. The relationship of the combined area of the tubes available for sodium conduction, and the volume of the interior space, as defined by the quotient: ##EQU1## (in which l is a unit length), has a value of at least 1.0 l.sup.-1.
Claims19
A high temperature rechargeable electrochemical cell which comprises a housing defining an interior space, a ceramic solid electrolyte separator located in the housing and dividing the interior space into an anode compartment and a cathode compartment, an alkali metal active anode material located in the anode compartment, and an active cathode material located in the cathode compartment and electrochemically coupled by the solid electrolyte separator to the active anode material, the cell having an operating temperature at which the active anode material is molten and the solid electrolyte separator being of a material which is a conductor of cations of the active anode material, the solid electrolyte separator comprising a multiplicity of at least 5 ceramic solid electrolyte separator tubes, each tube having an open end and a closed end, the active cathode material being located in the interiors of the tubes and each tube having its open end hermetically sealed to an associated opening leading from the tube into a header space defined by a header comprising electronically insulating ceramic material, the relationship of the combined area of the tubes available for conduction of cations of active anode material between the anode compartment and the cathode compartment, and the volume of the interior space, as defined by the quotient:
- ##EQU4## (in which l is a unit of length), having a value of at least 1.0 l.sup.-1, the tubes being arranged side-by-side to define a multiplicity of at least 6 longitudinally extending spaces therebetween and the cell comprising a multiplicity of anode current collectors in the form of electronically conductive rods located respectively in said spaces defined between the tubes.
A high temperature rechargeable electrochemical cell which comprises a housing defining an interior space, a ceramic solid electrolyte separator located in the housing and dividing the interior space into an anode compartment and a cathode compartment, an alkali metal active anode material located in the anode compartment, and an active cathode material located in the cathode compartment and electrochemically coupled by the solid electrolyte separator to the active anode material, the cell having an operating temperature at which the active anode material is molten and the solid electrolyte separator being of a material which is a conductor of cations of the active anode material, the solid electrolyte separator comprising a multiplicity of at least 5 ceramic solid electrolyte separator tubes, each tube having an open end and a closed end, the active cathode material being located in the interiors of the tubes and each tube having its open end hermetically sealed to an associated opening leading from the tube into a header space defined by a header comprising electronically insulating ceramic material, the relationship of the combined area of the tubes available for conduction of cations of active anode material between the anode compartment and the cathode compartment, and the volume of the interior space, as defined by the quotient:
- ##EQU5## (in which l is a unit of length), having a value of at least 1.0 l.sup.-1, the cell being of an alkali metal-transition metal/transition metal halide type, having a cathode which comprises an electronically conductive electrolyte-permeable porous matrix having a porous interior in which the active cathode material is dispersed in finely-divided particulate and/or thin-layer solid form, the matrix being impregnated by a molten salt electrolyte which saturates the porous interior of the matrix, the molten salt electrolyte being a sodium aluminium chloride electrolyte doped by at least one dopant which acts to lower its melting point but which is otherwise compatible with the cell cathode environment, the cell having a dopant content which in total forms 1-30% by mass of the molten salt electrolyte, each dopant being selected from the group consisting of zirconium tetrachloride, hafnium tetrachloride, quaternary ammonium halide salts, and any mixtures thereof, any said tetrahalide salts forming in total 5-10% by mass of the molten salt electrolyte and any said ammonium halide salts forming in total 10-30% by mass of the molten salt electrolyte.
Dependencies are inferred from the claim text.