GB476554A - Improvements in or relating to dry batteries - Google Patents

Abstract

476,554. Batteries. MACCALLUM, F., and REDFERN, A. H. March 9, 1936, No. 24996/35. [Class 53] A diaphragm for separating the electrodes in a dry battery consists of a number of paper or other porous sheets some or all of which are coated with electrolyte, the sheets being pressed together to form a laminated diaphragm. Fig. 2 shows a diaphragm 8 formed in this way and Fig. 1 shows a dry battery incorporating such diaphragms between zinc plates 5 and depolarizing tablets 7 which abut against carbon electrodes 6 which may consist of coatings on the zinc plates to form bipolar electrodes. The battery thus comprising a number of cells in series is covered with an elastic laminated skin which may be of the kind described in Specifications 423,165, and 466,597, [Group I]. The diaphragm 8 may be used in cylindrical cells with rod or plate type carbon electrodes surrounded by the usual cylindrical mass of depolarizer. The sheets of the diaphragm are preferably stepped in this case so that when bent into cylindrical form the joins formed by the meeting edges do not coincide. The diaphragm may consist of four to ten sheets of paper, each one thousandth of an inch thick and may be made by first coating a continuous length of paper by unwinding it from a roll and passing it through a bath of electrolyte and then between a pair of squeezing rollers or by applying the electrolyte to the paper by rollers or endless bands dipping in the electrolyte. The coated paper is then cut into sheets of the required size. The various sheets forming the diaphragm may be coated with different electrolytes. The sheet lying next to the zinc electrode may for example be coated with mercury chloride, zinc and ammonium chlorides being applied to the remaining sheets the amount of zinc chloride decreasing towards the sheet adjacent the carbon electrode.