Abstract: A cathode structure for a sodium sulphur cell is formed by putting a fibre matrix into a mould which is closed to shape the matrix to the required form with compression of the fibrous material, the mould being kept at a temperature below 12.degree. C. and preferably between 8.degree. and 10.degree. C. while liquid sulphur is injected into the compressed fibre material.

Abstract: For filling sodium into the sodium reservoir of a sodium-sulphur cell, the reservoir is closed except for an open-ended metal filling tube. In a filling machine, the cell is heated to a temperature such that the sodium will remain liquid, the tube is temporarily sealed around a sodium outlet of the filling machine by an inflatable seal, the reservoir is evacuated of air, flushed with an inert gas and then evacuated for vacuum filling with a metered quantity of sodium through a sodium feed tube within said outlet and extending downwardly into the filling tube. The sodium is pressurized using an inert gas to force the sodium into the cell, the gas is evacuated and the filling tube on the cell sealed by pinching and welding.