Lilliwyte Societe Anonyme

Programme 3 Patent Holdings

Chloride Silent Power, Ltd.

The Secretary of State for Industry in Her Britannic Majesty's

Other

United Kingdom Atomic Energy Authority

South African Inventions Development Corporation

Roger J Bones

David A Teagle

Johan Coetzer

Roy C Galloway

James H Duncan

Leslie Samuel Evans

John Richard Harbar

Geoffrey J May

Ivor E Denton

Derrick J Baker

Marion R Rance

Trevor Leslie Markin

Roger J Wedlake

Michael L Wright

Graham Robinson

Peter J Bindin

Michael P Brennan

James L Sudworth

Keith R Linger

Keith Taylor Scott

David L Segal

Jacobus H De Jager

Patrick T Moseley

Steven D Brooker

Stephen D Brooker

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

An electrochemical cell 10 housing a cylindrical housing 12 and a solid electrolyte separator tube 24 located concentrically therein, dividing the housing into an electrode compartment in the tube and an electrode compartment outside the tube. The cell has a solid electrolyte holder 36, 74 located in the tube and containing active electrode material 54. One of the electrode compartments contains active anode material, the other containing active cathode material. The electrode material in the holder is in electronic contact with the electrode material 54 in the housing outside the tube.

Electrochemical cell

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 solid electrolyte separator for separating two electrodes from each other in an electrochemical cell. The separator is of composite layered construction and comprises at least one porous layer of solid electrolyte material having a plurality of interconnected channels or pores in its interior and opening out of its surface, and a dense layer of non-porous solid electrolyte material. The layers are integrally bonded together, face-to-face, and each porous layer is an outer layer of the separator.

Method of making a solid electrolyte separator

The invention provides a compressed envelope of solid electrolyte for holding an electrode in an electrochemical cell. The envelope comprises corrugated sheets joined along their edges. The sheets are aligned with each other so that their corrugations extend parallel along the length of the envelope and a space is defined between the sheets. The corrugations of the sheets nest in each other where the sheets are joined together at the ends of the envelope. The invention also provides a method of making the envelope and a cell having an electrode held in said envelope.

Electrode holder

The invention provides a method of making a flattened solid electrolyte, e.g. .beta.-alumina, envelope for use as an electrode holder in an electrochemical cell. A mouldable mixture of the .beta.-alumina with a binder is formed into sheet material and two panels of the sheet material are joined together along their peripheral edges to form the envelope. Spacing and reinforcing means is provided between the panels to space them apart and to reinforce the envelope. The edges of the panels are joined together using pressure, heat and/or solvent, after which are envelope is heated to cure the binder, volatilize the cured binder and sinter the solid electrolyte.

The invention provides a rechargeable electrochemical power storage cell. The cell has an anode compartment defined between a cell casing and a separator, the anode compartment containing active anode material which is liquid at the operating temperature of the cell. The separator defines a cathode compartment containing an electrolyte which is liquid at the operating temperature of the cell, and an active cathode material. The separator separates said compartments from each other and during discharge of the cell the active anode material passes from the anode compartment to the cathode compartment through the separator, to enter the cathode compartment in ionic form. The active anode material passes through the separator from the cathode compartment to the anode compartment during charging of the cell. At least one of said compartments is sealed and is provided with switch means, which switch means is operative in response to an excursion, past a threshold value, of pressure in the sealed compartment arising from passage of active anode material through the separator during operation of the cell while it is connected to an external circuit, to prevent further operation of the cell while said pressure remains past said threshold value.

The invention provides a method of protecting an electrochemical cell which has a molten sodium anode, a chloride-ion containing sodium aluminum halide molten salt electrolyte, an iron-containing cathode in contact with the electrolyte and a solid conductor of sodium ions which separates the anode from the electrolyte, from the adverse effects of overcharging. The method comprises operating the cell, to prevent oxidation of iron to FeCl.sub.3 in the cathode, by connecting it in parallel with a protective cell having an open circuit charging plateau at a voltage less than the open circuit voltage of the Fe/FeCl.sub.3 //Na plateau of the cell being protected, and greater than the open circuit voltage, in its fully charged state, of the cell being protected. The invention also provides a cell of this type protected in this fashion, a battery including one or more such protected cells, and a cathode for such cells.

The invention provides a rechargeable electrochemical cell comprising a cell housing 10 divided by a separator 20 into a pair of electrode compartments, one of which contains an anode substance and the other of which contains an active cathode substance and an electrolyte. The anode and electrolyte are liquid at the operating temperature of the cell and the electrode compartments are each divided into a gas chamber communicating with an electrode chamber. The gas chamber contains an inert gas under pressure and the electrode chamber contains a liquid, namely the anode material or the liquid electrolyte. A wall of each electrode chamber is provided by the separator and each electrode chamber has a closeable bleed outlet 74, 80. The cell has an operative attitude in which said bleed outlets can be used to bleed gas from the associated electrode chambers, and each electrode chamber is in communication with the associated gas chamber, such that the cell in its operative attitude has each electrode chamber completely full of liquid, and each gas chamber containing inert gas under pressure and liquid.

A method of making a cathode suitable for an electrochemical cell of the type having a molten sodium anode, a beta'-alumina separator, and a cathode which comprises one or more transition metals selected from the group comprising Fe, Ni, Co, Cr and Mn. The method comprises heating a particulate starting material comprising at least one member of the group of transition metals in an oxidizing atmosphere to cause its particles to become at least partially oxidized, and to adhere together to form a unitary porous matrix. This matrix is then heated in a reducing atmosphere at least partially to reduce the oxide formed during the formation of the matrix, and the reduced matrix is then impregnated with a sodium aluminium chloride molten salt electrolyte. Sodium chloride in dispersed form is incorporated into the matrix, preferably by mixing sodium chloride in particulate form with the particulate transition metal starting material, before the heating in an oxidizing atmosphere to form the matrix.

Method of making a transition metal electrode

The invention provides a cathode for an electrochemical cell, an electrochemical cell including the cathode, and a method of resisting a progressive drop in the capacity of the cathode with repeated charge/discharge cycling thereof. The invention involves doping the electrolyte, which is a sodium aluminium halide molten salt electrolyte containing chloride ions, and/or the active cathode substance, which is a nickel containing substance with a minor proportion of a chalcogen so that the chalcogen is dispersed therein.

An electrochemical cell is provided with a molten sodium anode and a molten sodium aluminium halide salt electrolyte. The cathode comprises FeCl.sub.2, NiCl.sub.2, CoCl.sub.2 or CrCl.sub.2 as active cathode substance dispersed in an electronically conductive electrolyte-permeable matrix which is impregnated by the electrolyte. Between the anode and the electrolyte, and isolating them from each other, is a solid conductor of sodium ions or a micromolecular sieve which contains sodium sorbed therein. The proportions of sodium and aluminium ions in the electrolyte are selected so that the solubility of the active cathode substance in the electrolyte is at or near its minimum.

The invention provides a method of making a cathode for an electrochemical cell which involves incorporating sodium chloride in dispersed form into an electrolyte permeable matrix and impregnating the matrix with a suitable sodium aluminum halide molten salt electrolyte. The matrix is formed from a transition metal selected from at least one member of the group consisting of Fe, Ni, Co, Cr and Mn, and the intermediate refractory hard metal compounds of said transition metals with at least one non-metal selected from the group consisting of carbon, silicon, boron, nitrogen and phosphorus.

Growing community of inventors

Abingdon, United Kingdom

Roger J Bones