Abstract: Beta-alumina ceramic articles of improved strength and durability particularly for use in sodium sulphur cells are produced by compacting beta-alumina particles or a mixture of powders which react to form beta-alumina, sintering the compacted material in air or oxygen to form an impervious polycrystalline ceramic body and then further densifying the sintered body by subjecting it to the direct isostatic pressing action of a fluid, e.g. a gas at a pressure of at least about 5,000 psi and at a temperature between 1200.degree. C and 1500.degree. C which is above the elastic/plastic transformation, said fluid being inert and non-permeating with respect to said fired body and subsequently cooling the body under pressure to a temperature below the elastic/plastic transformation.

Abstract: In an electrochemical cell, such as a sodium sulphur cell, having a solid ceramic sodium-ion permeable electrolyte forming part of the boundary of a sodium-containing region, to seal this region, the ceramic electrolyte or a ceramic extension thereof is sealed to a metal housing or metal closure element using glass with the glass-to-metal interface protected against the effect of sodium vapour by a niobium coating over the metal in the region where the interface is exposed to the sodium or this interface is protected from such exposure by niobium foil.

Abstract: In an electrochemical cell, such as a sodium-sulphur cell, having a tube of solid electrolyte material separating a liquid alkali metal from a cathodic reactant, the electrolyte tube is surrounded by constraining means which apply an inward pressure as the cell temperature rises. This is achieved either by having a suitable means, e.g., wire, around the tube with a lower coefficient of expansion than the tube, or by putting powder or particles or corrugated metal or other constraining means between the tube and a surrounding housing, the materials being chosen to have appropriate coefficients of expansion to give the required inward pressure.

Abstract: In a sodium-sulphur cell having a solid electrolyte and a cathode current collector with a porous conductive matrix, e.g. carbon or graphite felt, in the region between the electrolyte and the current collector, the matrix is formed of a plurality of discrete elements with electronically conductive material, e.g. graphite foil, between the elements extending across the region between the current collector and the electrolyte to increase the conductivity across that region.

Abstract: An alkali metal sulphur cell has an outer tubular casing and an inner tubular solid electrolyte whose interior constitutes the cathode compartment of the cell. The outer tubular casing and the tubular solid electrolyte are spaced apart to define an annular space, at least the part of which adjacent the outer surface of the tubular solid electrolyte constitutes the anode compartment of the cell. Means are provided for causing the alkali metal to be distributed over the outer surface of the tubular solid electrolyte. Barrier means additional to the solid electrolyte are disposed between the sulphur material and at least a part of the outer casing. The barrier means may comprise a coating on one or both surfaces of the tubular solid electrolyte, alkali metal flow restrictor means or a coating on at least a part of the inner surface of the outer casing.

Abstract: A thermo-electric generator of the kind making use of beta alumina ceramic through which sodium is circulated to produce an electric potential between the two surfaces of the ceramic has the ceramic in the form of a tube closed at its upper end and with its open end extending into liquid sodium. A heat pipe extends into the ceramic tube and there is an external tubular casing around the ceramic tube forming a closed structure for housing sodium in liquid and vapor form both inside and outside the ceramic tube. The heat pipe may be arranged either as a heat source or heat sink for the sodium inside the ceramic tube, the housing forming the heat sink in the former case of the heat source in the latter. The ceramic tube may, at its open end, be sealed to the housing and a pump used for pumping the sodium from the cold face to the hot face of the ceramic or capillary means may be used to circulate the sodium.

Abstract: An alkali metal-sulphur cell of tubular form, has an inner tubular member constituting the solid electrolyte, an outer tubular member and a current collecting pole extending into the interior of the inner tubular member which forms the cathode compartment of the cell. The outer tubular member, the inner tubular member and the current collecting pole have shoulder formations which abut one another through sealing means and are urged towards one another by axially acting spring means.