Lilliwyte Societe Anonyme

South African Inventions Development Corporation

Programme 3 Patent Holdings

Electro Chemical Holdings Societe Anonyme

Aabh Patent Holdings Societe Anonyme

Bi-patent Holdings, S.a.

Johan Coetzer

Roger J Bones

David A Teagle

Michael M Thackeray

Roger J Wedlake

Roy C Galloway

Isak L Vlok

James H Duncan

Keith T Adendorff

Anthony A Meintjes

Derrick J Baker

Marion R Rance

Margaretha J Nolte

Annemare De Kocknee Steynberg

Patrick T Moseley

Margaretha Nolte

The invention provides a method of making a ceramic solid electrolyte separator for a high temperature electrochemical cell from a particulate starting material capable of being sintered to form a unitary polycrystalline solid electrolyte ceramic artifact. The method includes admixing the particulate starting material with a binder to form an extrudable mixture, extruding the mixture to form a unitary sinterable green artifact including a multiplicity of at least five tubes interconnected together in side-by-side relationship and sintering the green artifact to form a sintered polycrystalline ceramic solid electrolyte artifact. The artifact includes a multiplicity of at least five ceramic solid electrolyte separator tubes interconnected together by sintering and arranged in side-by-side relationship.

Electrochemical cell separator

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.

High temperature electrochemical cell with molten alkali metal anode

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 an anode compartment and a cathode compartment separated from each other by a separator. The cathode compartment contains a current collector; an alkali metal aluminium halide molten salt electrolyte having the formula MAlHal.sub.4 ; an alkali metal halide; and a cathode. The cathode comprises an electrolyte-permeable porous matrix, a first active cathode substance in the matrix in a first zone adjacent the current collector and spaced from the separator, and a second active cathode substance in the matrix in a further zone adjacent the first zone. The first active cathode substance is such that it gives rise to a higher cell potential than does the second active cathode substance. The cell is chargeable at a temperature at which the electrolyte and the alkali metal are molten to cause the active cathode substances to be halogenated.

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.

Electrochemical cell, method of making such and precursor therefor

The invention provides a method and apparatus for making an electrochemical cell solid electrolyte holder. A layer of solid electrolyte powder or its precursor is formed around an externally screw threaded mandrel. The powder is pressed to form the holder in a green state with internal threads formed by the mandrel. The mandrel is screwed axially out of the green holder, after which the green holder is sintered. In the apparatus there is a mandrel which has external threads, and a flexible sheath. The mandrel is receivable in the sheath to provide an annular space around the mandrel for receiving a powder to be isostatically pressed by the sheath. The space is provided between the sheath and a mold, but can, instead, be provided between the mandrel and sheath, or between two sheaths between the mold and mandrel.

Electrolyte holder

A laterally compressed envelope of solid electrolyte material is provided for use as an electrode holder in an electrochemical cell. It has two opposed major faces sealed together along at least part of the periphery of the envelope, each major face being provided by a sheet of said solid electrolyte material. Each sheet is provided on its inner surface with a plurality of ribs or corrugations extending alongside one another, each rib or corrugation of each said sheet crossing over a plurality of the ribs or corrugations of the other said sheet. The envelope has an internal volume, between the sheets, defined at least in part by grooves or valleys between the ribs or crests of the corrugations. Each part of said internal volume is in communication with each other part of said internal volume. The invention also provides a method of making the envelope, and an electrochemical cell in which the envelope forms an electrode holder.

Electrochemical cells

The invention provides a method and apparatus for making an electrochemical cell solid electrolyte holder. A layer of solid electrolyte powder or its precursor is formed around an externally screw threaded mandrel. The powder is pressed to form the holder in a green state with internal threads formed by the mandrel. The mandrel is screwed axially out of the green holder, after which the green holder is sintered. In the apparatus there is a mandrel which has external threads, and a flexible sheath. The mandrel is receivable in the sheath to provide an annular space around the mandrel for receiving a powder to be isostatically pressed by the sheath. The space is provided between the sheath and a mould, but can, instead, be provided between the mandrel and sheath, or between two sheaths between the mould and mandrel.

Apparatus for making a solid electrolyte holder

The invention provides a high temperature rechargeable electrochemical power storage cell comprising a cell housing defining a cathode compartment containing a cathode and containing an anode structure located within the cathode compartment and comprising a plurality of holders filled with active anode material which is molten at the operating temperature of the cell. The anode structure defines a conduit containing active anode material and the holders are flattened in shape and spaced along the conduit in series from one another. The interior of each holder is in communication with the conduit and each holder has a pair of oppositely outwardly facing major faces extending transversely to the conduit and comprising a material which is a conductor of the active anode material. The cathode occupies the spaces between the holders and the cell includes a reservoir for active anode material in communication with the conduit, the reservoir in all states of charge of the cell being at least partially filled with active anode material.

The invention provides an anode for an electrochemical cell. There is an anode holder containing a molten sodium anode. The holder is a ceramic envelope which is a sodium conductor and the holder has a current collector in contact with the sodium and projection through an opening in the envelope wall. The envelope interior contains a unitary porous solid matrix permeable by and impregnated by sodium. The matrix is bonded to at least part of the inner surface of the wall of the envelope. The invention provides also a holder for the anode which is empty of sodium; and provides an electrochemical cell employing the anode; and it provides a method of making said anode and holder.

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.

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.

The invention provides a high temperature rechargeable electrochemical power storage cell having an alkali metal anode molten at the cell operating temperatrure. A solid electrolyte separator conductive of ions of the anode separates the anode from a cathode having an electronically conductive electrolyte-permeable porous matrix impregnated with liquid electrolyte comprising cations of the anode metal and halide ions. Dispersed in the porous interior of the matrix is an electronically active cathode substance substantially insoluble in the liquid electrolyte. The separator is a sheet and the matrix of the cathode has the same peripheral outline as the sheet. The matrix is opposed to the sheet and is in register face-to-face therewith. The separator and sheet are located in a cell housing divided by the separator into an anode compartment containing the anode and a cathode compartment containing the cathode.

Growing community of inventors

Pretoria, South Africa

Johan Coetzer