Patent GB-441327-A (GB)
Title: Improvements in or relating to electric cells
IPC: H01M12/06
Filed: 1934-04-09
Abstract: 441,327. Batteries. GILLAN, F. A., 265, Ridge Road, Durban, Natal, South Africa. April 9, 1934, Nos. 10688 and 26234. [Class 53] A primary cell has a positive electrode consisting of at least two kinds of carbon one of which is wetted and one of which is not wetted by the electrolyte, the mixture being in powder form and packed into a porous envelope. A part of the electrode is exposed to the air the oxygen of which penetrates the electrode and has access to the surface of the electrode where it is in contact with the electrolyte. The extent to which the electrode is permeable to air and impermeable to electrolyte can be adjusted by subjecting the powdered carbon mixture to a predetermined pressure in the porous envelope. Natural gas black, carbon black or other form of active carbon may be incorporated in the electrode and may be concentrated towards the surface of the electrode where polarization occurs. Carbon which is not wetted by the electrolyte may be made from powdered carbon that is wetted by treating the latter with an ethereal solution of a paraffin or with the vapour from heated tar. The electrode may finally be subjected to a temperature of 190‹ F. in a closed chamber. The electrode may be used in a cell of the Leclanche type in which case the carbon mixture is contained in a fabric sheath which may be impregnated with paraffin and dried. The upper part of the electrode projects above the electrolyte. The electrode may also be employed in cells having caustic soda electrolyte in which case the carbon mixture is packed into a perforated container of iron, steel, nickel or nickelplated iron or steel. Two such containers may be used, the carbon being packed between them, the centre container being empty and serving to facilitate ingress of air. Ventilating shafts may be provided in the electrode for the same purpose. The negative electrode may be of zinc and to ensure that this is consumed from the bottom upwards the current may be taken from the bottom of the positive electrode. Fig. 1 shows a cell employing a caustic soda electrolyte and a zinc electrode 4 and in which the positive electrode consists of powdered carbon as described above packed into perforated containers 2, 3 of iron, steel or nickel or nickel-plated iron or steel. Ventilating grooves 7 are provided by using corrugated metal for parts of the containers. The electrolyte is covered with oil which is kept away from the protruding parts of the containers 2, 3 by providing the latter with layers of insulating material 11. Current leads 12 are attached to the lower ends of the electrodes. Ventilating shafts may be provided down the centre of the electrodes, and a single carbon electrode may be used with a zinc electrode on each side. Fig. 3 shows a modification in which the carbon powder is packed between two perforated containers 20, 21 the inner one being provided with ventilating shafts 22 and current leads 24 being attached to the lower end of the outer container. Both containers may be cylindrical as shown in Fig. 3, or they may diverge outwards towards the bottom so that the surrounding zinc electrode is nearer to the carbon electrode at the bottom than the top and the zinc is consumed from the bottom upwards. Fig. 5 shows a further modification in which the carbon mixture 29 is contained in a perforated container 26 of rubber, porcelain &c. In the centre of the electrode is a carbon tube 25 provided with radial passages 28 and having a lead ingot 30 cast in its lower end in which a current lead 31 is embedded. Tne carbon mixture 29 may consist of two kinds of vegetable black one of which is wetted and one of which is not wetted by the electrolyte together with a quantity of gas black the whole being compressed into the perforated container under a pressure of 75 lbs. per square inch.