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South African Inventions Development Corporation

Programme 3 Patent Holdings

Electro Chemical Holdings Societe Anonyme

Roger J Wedlake

Johan Coetzer

Roger J Bones

Rodney C Baxter

Bodo R Rohrmann

Gordon Brodie

Ro Slashedger Bones

Anthony L Penny

David L Segal

Gerhard J Mostert

Johan Goetzer

A high temperature rechargeable electrochemical cell is provided, comprising a housing divided by a pair of concentric separator tubes into two anode compartments each containing molten alkali metal active anode material, the alkali metal in each anode compartment being electronically connected to the alkali metal in the other anode compartment, and a cathode compartment sandwiched between the anode compartments. The cathode compartment contains cathode material comprising a porous electrolyte-permeable electronically conductive matrix with a charged state in which it has a transition metal halide active cathode material dispersed therein, the matrix being impregnated with molten salt electrolyte. The cell comprises a cathode current collector tube located between the separator tubes, so that an inner part of the cathode is located between the smaller separator tube and the current collector tube, an outer part of the cathode being located between the current collector tube and the larger separator tube.

Electrochemical cell

A high temperature storage battery comprises a plurality of panels forming a housing defining a cell storage cavity, heat insulating material in or adjacent the panels, and a non-aqueous high temperature electrochemical cell within the cell storage cavity. It also includes holding means for holding a dispersable protective substance. The holding means is adapted to discharge protective substance into the cavity on the temperature in the cavity exceeding a predetermined temperature, and/or on rupturing thereof.

High temperature storage battery

This invention provides a process for the recovery of titanium values from a complex matrix comprising titanium nitride. The process comprises chlorinating the titanium nitride in the matrix to obtain a reaction product containing titanium chloride, and separating the titanium chloride from the reaction product. The invention also provides for the production of said complex matrix containing titanium nitride by nitriding titanium values in complex titanium-containing starting materials such as complex metallurgical titaniferous slags and ilmenite, perovskite, armalcolite and fassaite.

Procss for the recovery of titanium values

The invention provides a high temperature electrochemical cell having an anode and a cathode separated by a separator. The cell has a housing divided by the separator into two cell compartments for the anode and cathode, each of which compartments contains liquid at the cell operating temperature, and has a gas space therein above the liquid, containing an inert gas. The cell compartments are in communication with each other, e.g. by passage, and are otherwise sealed. This communication is above the levels of the liquid in the compartments at all stages of charge of the cell.

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.

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.

A method of making an (alkali metal) (metal) halide compound and an alkali metal, the compound having the formula MDHal.sub.x+1 in which D is a metal; M is an alkali metal; Hal is a halide; and x is the valency of the metal D. The compound is made by exposing to one another a molten MDHal.sub.x+1 compound, a metal D and an alkali metal halide having the formula MHal. The MDHal.sub.x+1 compound is separated from a molten alkali metal M by means of a separator which is in contact with both the molten MAlHal.sub.4 and molten alkali metal. The separator can include a solid conductor of ions of the alkali metal or a micromolecular sieve having the alkali metal absorbed therein. A sufficient electrical potential is applied across the electrolytic cell D/MHal/MDHal.sub.x+1 .parallel.separator.parallel.alkali metal to cause the following reactions to take place: xMHal+D.fwdarw.XM+DHal.sub.x and MHal+DHal.sub.x .fwdarw.MDHal.sub.x+1. The alkali metal formed in the first reaction passes through the separator and into the molten alkali metal. The electrical potential is a direct current potential arranged so that electrons are fed via an external circuit into the molten alkali metal.

Manufacture of an alkali metal aluminum halide compound and alkali metal

The invention provides a method of making an electrochemical cell. The method comprises loading, into the cathode compartment of the cell 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 the same alkali metal and halide as in the molten salt electrolyte; aluminium; and an active cathode substance which includes a transition metal T selected from the group conprising Fe, Ni, Co, Cr, Mn and mixtures thereof. An electrochemical cell precursor is thereby made. When the precursor is subjected to charging at a temperature at which the molten salt electrolyte and alkali metal M are molten, aluminium reacts with the alkali metal halide MHal to produce further said molten salt electrolyte and to form said alkali metal M, the alkali metal M passing through the separator into the anode compartment. After all the aluminium has reacted with the alkali metal halide to provide a cell in a discharged state, the active cathode substance is halogenated, with further alkali metal M being produced and passing through the separator into the anode compartment, the proportions of alkali metal halide MHal, molten salt electrolyte and aluminium loaded into the cathode compartment being selected so that when the cell is fully charged and all the available active cathode substances has been halogenated, the proportion of alkali metal ions and aluminium ions in the electrolyte being selected such that the solubility of the active cathode substance in the molten electrolyte is at or near its minimum.

The invention provides a power storage battery (10) comprising a multiplicity of interconnected identical electrochemical power storage cells (11) whose internal resistance varies with their temperature. The cells are interconnected into a plurality of groups (16, 18, 31) with each group comprising a plurality of the cells, at least some of which are connected in series. The groups are connected in parallel and the battery in use has a temperature profile whereby at least some of its cells are at different temperatures from one another. The cells of each group are located and interconnected so that, in use, each group has substantially the same internal resistance as any other group.

Power storage battery

A battery of interconnected high-temperature rechargeable electrochemical cells, a method of operating the battery and support means for supporting and heating the battery are provided. The support means acts to carry the cells and to heat the cells from below. Heating the cells from below is electrical and/or by circulating heated gas through a plinth on which the cells rest, the gases being derived from the catalytic conversion of a hydrocarbon fuel.

Battery comprising high temperature rechargeable electrochemical cells

A method and means for reducing the potential hazard presented by escaping electrochemical cell contents are disclosed. The invention involves associating a micromolecular sieve carrier with the cell to sorb such contents when they escape, to reduce the severity of undesired reactions of such contents. The sieve carrier is conveniently associated with the cell by being provided in a layer, e.g. in a holder, around the cell.

Electrochemical cell and the protection of an electrochemical cell

This invention relates to a novel hard material which may be used as an abrasive and a method of making the material. The material consists essentially of B.sub.x C.sub.y N.sub.z, wherein x, y and z can have any value greater than 1, in tetrahedral form. The preferred material is BCN. The material is made by subjecting an appropriate source of boron, nitrogen and carbon to conditions of temperature and pressure sufficient to produce the material. The preferred method is to subject boron carbonitride in hexagonal or amorphous form in the presence of an appropriate solvent for the substance such as an aluminium/iron alloy to a pressure exceeding 50 kilobars and simultaneously a temperature exceeding 1300.degree. C.

Growing community of inventors

Johannesburg, South Africa

Roger J Wedlake