Patent GB-667298-A (GB)
Title: Improvements relating to galvanic cells and batteries
IPC: H01M4/86
Filed: 1949-06-08
Abstract: 667,298. Batteries. BRITISH ELECTRICAL & ALLIED INDUSTRIES RESEARCH ASSOCIATION, and BACON, F. T. Sept. 5, 1950 [June 8, 1949], No. 15326/49. Class 53. A gas battery comprises a pair of porous metal electrodes 1, 2 of disc shape, the rims 3 of which are non-porous and separated by insulation 8a, the whole being clamped between steel members 5, 6 having an inlet 10 and outlet 13 for electrolyte which passes between the electrodes 1, 2. Porous separators may be provided between the electrodes. Tubes 19, 21 lead oxygen and hydrogen respectively to the outer surfaces of the electrodes, the gases being removed through pipes 20, 22. The electrolyte may consist of a solution of caustic potash or soda. Terminals for the cell are secured to the members 5, 6. The pores on the outer surfaces of the electrodes 1, 2 which are in contact with the gases are of larger size than those on the inner surfaces in contact with the electrolyte so that the difference in pressure across each electrode is sufficient to force the electrolyte out of the pores on the gas side but insufficient to cause the gas to bubble through into the electrolyte between the electrodes. The electrodes may be made of nickel by compressing a mixture of nickel powder and ammonium bicarbonate on to a thin layer of nickel powder mixed with a volatile material to form a coherent layer. The nickel powder may be prepared from nickel carbonyl. The two layers are sintered together on a refractory plate, the two surfaces of the finished electrode then having different porosities. The non-porous rims 3 are made by compressing the circumferential portions of the electrodes and resintering them at a low temperature. The electrodes are finally ground to correct dimensions. The electrodes may be activated by impregnating them with nickel acetate and heating in hydrogen to reduce the acetate to metallic nickel. Cobalt or silver may be used in place of nickel. The complete cell with connections for the circulation of electrolyte and supply of oxygen and hydrogen is shown in Fig. 3, the supply tubes 10, 19, &c. being provided with insulating flanges 11, 19a, &c. to insulate the cell from earth. The pairs of tubes 19, 20 and 21, 22 are connected by pipes 23, 24 to promote circulation of the gases. Electric heaters may be placed in contact with the outer faces 30 of the members 5, 6 and a heater 31 may surround the pipe 28 which delivers electrolyte to the cell and which is connected to the outlet 13. The cell is filled with electrolyte by first removing air through a connection 32, the valve 44 being closed, and then opening the valve 44 and allowing electrolyte to be drawn in through a pipe 33 connected to a supply of electrolyte. Indicator glasses 41 and tubes 39, 40 are also connected to the electrolyte supply so that electrolyte is drawn into the gas spaces in the cell outside the electrodes. A gauge glass 34 shows when the whole system is full of electrolyte. Valves 32a and 38 are then closed and electrolyte in the gas spaces in the cell expelled by admitting oxygen and hydrogen from cylinders 45, 46, the expulsion of the electrolyte being indicated  by the glasses 41 and the total pressure in the apparatus being indicated by a gauge 43. The valve 44 is then closed and the cell heated to commence operation during which the gases in the cell circulate through the pipes 19, 20, 23 and 21, 22, 24. During the operation of the cell, water is formed which dilutes the electrolyte and tends to raise the level of the liquid in the glasses 41. To keep this level constant electrolyte is slowly released through the valve 44. A modification of the apparatus on the hydrogen side of the cell is described in which pure water is withdrawn from the apparatus instead of electrolyte, thus allowing the cell to be operated for long periods without dilution of the electrolyte. The water may be released automatically by a float-operated valve.