Patent GB-579326-A (GB)
Title: Improvements in or relating to primary cells and batteries
IPC: H01M6/06
Filed: 1943-01-06
Abstract: 579,326. Batteries. BURGESS LABORATORIES, Inc., C. F. Jan. 6, 1943, No. 278. Convention date, Dec. 26, 1941. [Class 53] A primary cell having, before use, no substantial quantity of conductive electrolyte, comprises juxtaposed thin sheet-form elements arranged in the following order :-(1) a cathode of silver, gold, platinum or carbon, (2) a layer of depolarizing material, such as silver bromide, insoluble in water but capable of reacting with hydrogen to form a water-ionizable compound, (3) a layer of bibulous material, and (4) an anode of calcium or magnesium. The cell may be moistened with water free from any substantial quantity of dissolved electrolyte, or it may be dry and 'water may be added at any time before use. When the circuit is closed, the minute amount of dissolved salts, e.g., in tap water or derived from the bibulous material, permits a small current to flow, the hydrogen thus produced reducing the silver bromide (or other depolarizer) to form hydrobromic acid which increases the conductivity of the cell so that maximum current is rapidly obtained. Instead of silver bromide, silver chloride, iodide, or sulphide, or other insoluble sulphide, may be used as a depolarizer. The bibulous layer may consist of paper, cellulose fibre, cotton, rayon, glass, Vinyon (Registered Trade Mark), with or without a wetting agent. Ethyl alcohol, ethylene glycol, or sorbitol may be added to the water. Fig. 1 shows a cell having a magnesium anode 11, a silver cathode 10 having a thin coating 12 of silver bromide, the anode and cathode being separated by a thin sheet of paper &c. The cell is partially enclosed by a wrapper 14 which does not cover the ends of the cell, which may be moistened, before use, by dipping it in water. To increase the rapidity with which the current reaches its maximum, an aqueous solution of hydrobromic acid, sodium bromide &c. may be added before use. The silver bromide layer may be formed electrolytically or applied as a plastic paste made by mixing silver bromide with resins, glue, alkali metal silicates &c. or with fillers, such as bentonite. The elements of the cell may be in the form of strips wound together spirally in the form of a cylinder, Fig. 3 (not shown) which may be enclosed in a cylindrical wrapper, the ends being open so that the cell may be moistened by dipping in water. Alternatively, the moistened cell may be sealed in a cylindrical container, Fig. 5 (not shown), deterioration being inhibited by dipping the anode in a solution of chromic acid or a chromate, or by adding such a compound to the water used to moisten the cell. Alternatively, a drycell may be sealed in a closed container having a removable plug to permit the addition of water, Fig. 6 (not shown), or the cell may be inserted in an evacuated glass container, the cell being moistened by breaking the seal under water, Fig. 7 (not shown). A series of cells, such as shown in Fig. 1, may be combined to form a battery, Fig. 8 (not shown), the anode of one cell being soldered to the cathode of the next, the remainder of the surfaces of these electrodes being separated by thin insulating material, such as a composition of rubber and paraffin, or rubber, or an artificial resin.