GB1259052A - - Google Patents

Abstract

1,259,052. Electric battery. ESB Inc. 13 April, 1970, No. 17457/70. Heading H1B. A rechargeable electric cell comprises a negative electrode can 24, e.g. zinc, an insulator 29 lining the bottom, a laminated separator 26 lining the inner vertical walls of the can, a current collector 25, e.g. a carbon rod disposed in the can having a metal cap terminal 28 thereon, an azodicarbonamide depolarizer mix 27 filling the space between collector 25 and separator 26 to a distance below the top of electrode can 24, sealing means having a central aperture for collector 25 for sealing the open end of the can, so as to leave an air space above the depolarizer mix and below the sealing means, insulating means surrounding the collector in the air space, and vent means. In the embodiment shown in Fig. 1, the sealing means comprises a seal washer 31, e.g. kraft paper, covering the open end of the can which supports a sealing compound 32. An insulating cap washer 33 is provided on sealant 32, and a thin vent washer 42, e.g. a laminated construction of kraft paperpolyethylene-kraft paper, is provided on cap washer 33. The outer metal casing 21 and insulating liner 22 are crimped over the edges of metal cap 28 and vent washer 42. Gases produced in the cell enter porous carbon rod 25 and collect in area 40 under cap 28 and then escape through the crimped edge along the vent path provided by washer 42. The insulating means 34 surrounding collector 25 in the air space is preferably polyethylene. Separator 26 is preferably a laminate of "Cellophane" (Registered Trade Mark) 38, and an ethylene/vinyl acetate copolymer 39 having a gelling agent therein, such a starch wheat flour. Bottom insulator 29 is preferably a laminate of paraffined kraft paper 30 and non-conductive inert plastics material 35 such as polyethylene. In an alternative construction the sealant, vent washer and insulation about the carbon rod in the cell air space are combined in a onepiece polyethylene closure 49 (Fig. 3). Venting is accomplished through holes 52 and grooves 53. Gas passes from the cell interior through holes 52 into space 40 below cap 28 and flows in groove 53 and escapes through the crimped edge of casing 21. Closure 49 has central opening 56 for the carbon rod and a tubular projection 46 depending from the top, which projection surrounds and insulates the carbon rod in the cell air space. The side walls of the closure extending down from the flat surface are threaded at 55. The tubular projection may have a hole therein to permit gases to flow into the carbon rod.