SODIUM-SULPHUR CELL

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 (arrow A), slicing the block to form a sheet 7 with fibres normal to the plane of the sheet, moulding the sheet 7 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.