Chloride Silent Power, Ltd.

Peter J Bindin

John Molyneux

Roger J Bones

Ivor Wynn Jones

Graham Robinson

Michael P Brennan

Geoffrey J May

Gilbert Sands

Keith R Linger

Trevor Leslie Markin

Walter A Dawson

Batteries

Sodium sulphur cells are commonly connected in parallel. It is a problem with such arrangements that if one cell sustains a short circuit failure, the parallel connected cells discharge through it. In an embodiment disclosed, a switch series connected to a cell or series of cells, goes open circuit should current in excess of a predetermined value and consequently associated with the failure of a cell, flow through the switch. The switch comprises a conducting rod separated into two portions and placed within a beta alumina tube containing sodium: the level of the sodium determines whether an electrical circuit is completed between the portions rendering the switch 'on'. Sodium, contained within an outer conducting tube, also surrounds the inner beta alumina tube, there being an electrical connection from the outer tube, via a resistor, to one portion of the rod. Should a current flow in a direction through the switch corresponding to discharge through a failed series connected cell, the arrangement is such that sodium within the inner tube is at a higher potential than sodium outside the inner tube. Accordingly, sodium cations flow out of the inner tube resulting in the lowering of the sodium level until the switch turns off, thus preventing further discharge through the failed cell.

Alkali metal switch device

Alkali metal electro-chemical storage cell

In a sodium sulphur cell having, within a metal housing, a ceramic electrolyte tube separating the liquid alkali metal from the cathodic reactant, a current collector extends into the region inside the electrolyte tube and is electrically insulated from the electrolyte by an insulating element. The metal housing is sealed to the insulating element in a region around the current collector which region has a maximum cross-section substantially less than the maximum cross-section of the electrolyte tube and preferably lies wholly within the outer periphery of the electrolyte tube. The small seal areas with the constructions described give improved economy and reliability. The constructon has particular advantages with cells of short length.

Alkali metal cells and batteries and the manufacture thereof

A battery module for a sodium sulphur battery containing a plurality of cells comprises a container housing the cells with an evacuated region between the cells and the walls of the container, this evacuated region containing a plurality of layers of metal foil between the cells and the wall. At least one tube extends through the module in contact with the cells for conveying a thermally-conductive fluid by means of which the cells can be heated or cooled.

High temperature multicell electrochemical storage batteries

A sodium sulphur battery formed of a plurality of modules each containing a cell or cells has a passage through each module for a heating and/or cooling fluid and thermostatically controlled valve means for controlling the flow of fluid through this passage which valve means is open at temperatures above a predetermined temperature, e.g. 370.degree. C. for passage of a coolant fluid and is also open at temperatures below another predetermined temperature, e.g. 300.degree. C. for passage of a heating fluid. The valve is preferably gradually closed and opened between these tempteratures. Each valve is controlled in accordance with the temperature of the associated module.

Sodium sulphur batteries and cell modules therefor

In an electrochemical cell such as a sodium sulphur cell using a ceramic electrolyte tube (e.g. of beta-alumina), the electrolyte tube is secured to a rigid annular element of, for example, alpha-alumina, having substantially the same coefficient of thermal expansion as the electrolyte tube, this annular element being radially thicker than the electrolyte tube and having two oppositely sloping tapered surfaces on its outer face. Metal elements are then forced onto the tapered surfaces with an interstrate layer of soft metal, e.g. aluminium, which deforms into a groove or grooves in the tapered surfaces to form a hermetic seal.

Sealing of ceramic electrolyte tubes in electrochemical cells

In an electrochemical cell such as a sodium sulphur cell using a ceramic electrolyte tube (e.g. of beta-alumina), the electrolyte tube is secured to a rigid annular element of, for example, alpha-alumina, having substantially the same coefficient of thermal expansion as the electrolyte tube, this annular element being radially thicker than the electrolyte tube and having two oppositely sloping tapered surfaces on its outer face. Metal elements are then forced onto the tapered surfaces with an interstate layer of soft metal, e.g. aluminium, which deforms into a groove or grooves in the tapered surfaces to form a hermetic seal.

Method of sealing ceramic electrolyte material in electrochemical cells

A cathode current collector for a sodium sulphur cell is formed of a metal substrate, for example of a nickel alloy such as Inconel 600, which is provided with a firmly adherent coating of carbon which is produced by decomposition of a carbon-containing gas in a glow discharge with the substrate heated to a temperature of 200.degree. C. to 1000.degree. C. in an electric field, conveniently a radio frequency field employed for inductively heating the substrate.

Current collector for electrochemical cells and method of making

For sealing metal annular elements on to a cylindrical ceramic member, e.g. a ceramic electrolyte tube in a sodium-sulphur cell without causing excessive hoop stress in the ceramic, the ceramic tube is formed with tapered inner and outer surfaces at one end, correspondingly tapered inner and outer annular elements are put over these surfaces with a soft metal, e.g. aluminium interface layer, the inner and outer annular elements having coefficients of thermal expansion respectively less than and greater than that of the ceramic, the assembly is then heated and the annular elements forced in the axial direction onto the ceramic whereby the ceramic material, on cooling, is tightly secured between the annular members.

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Runcorn, United Kingdom

Peter J Bindin