Abstract: For a cylindrical sodium sulfur cell, a cathode electrode structure is provided with improved electronic conductivity in the radial direction, compared with other directions, by forming a block of fibre material, e.g. graphite fibres, with the fibres aligned in one direction, slicing the block to form a sheet with fibres normal to the plane of the sheet, moulding the sheet and impregnating it with cathodic reactant in a heated mould having a plurality of ribs, to form a plurality of trapezoidal segments with the fibres normal to the planes of the parallel surfaces of the trapezoids, cooling the mould so that the impregnant is solidified and then forming the trapezoids into an annular structure. Preferably the mould is such that thin webs are left joining adjacent trapezoidal sections along parallel edges of the wider of the two parallel faces so that the webs form hinges for folding the segments into the annular assembly.

Abstract: For a cylindrical sodium sulphur cell, a cathode electrode structure is provided with improved electronic conductivity in the radial direction, compared with other directions, by forming a block of fibre material, e.g. graphite fibres, with the fibres aligned in one direction, slicing the block to form a sheet with fibres normal to the plane of the sheet, moulding the sheet and impregnating it with cathodic reactant in a heated mould having a plurality of ribs, to form a plurality of trapezoidal segments with the fibres normal to the planes of the parallel surfaces of the trapezoids, cooling the mould so that the impregnant is solidified and then forming the trapezoids into an annular structure. Preferably the mould is such that thin webs are left joining adjacent trapezoidal sections along parallel edges of the wider of the two parallel faces so that the webs form hinges for folding the segments into the annular assembly.

Abstract: In a sodium sulphur cell, a cathode electrode of annular form comprising a plurality of segments, each of trapezoidal form in cross-section and joined by webs along a longer edge of each segment so that the assembly is foldable to form a substantially annular structure. This electrode may be made by compressing a blanket or sheet of carbon or graphite felt or fibres in a heated mould, which is shaped to produce the segments joined by thin webs, the material being impregnated with sulphur or sodium polysulphide before or after insertion in the mould, and the material being cooled before removal from the mould. Alternatively, the segments may be formed from the blanket or sheet by using shaped rolls, the material being cooled, e.g. by water or air, as it leaves the rolls.

Abstract: 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.

Abstract: In a sodium sulphur cell, a cathode electrode of annular form comprising a plurality of segments, each of trapezoidal form in cross-section is made by compressing a blanket or sheet of carbon or graphite felt or fibres in a heated mould, which is shaped to produce the segments joined by thin webs, the material being impregnated with sulphur or sodium polysulphide before or after insertion in the mould, and the material being cooled before removal from the mould. Alternatively, the segments may be formed from the blanket or sheet by using shaped rolls, the mateial being cooled, e.g., by water or air, as it leaves the rolls.

Abstract: In a sodium-sulphur cell, a cathode current collector, which extends into the cathodic region to provide a high conductivity current path, is formed of aluminium with a sheath over the surface of the aluminium or with finned elements secured to the aluminium, the sheath or fins being of a corrosion-resistant metal and being secured to the aluminium by bonding through a protective coating over the surface of the aluminium which serves to protect the aluminium from the cathodic reactant.