MXPA00009323A - End cap seal assembly for an electrochemical cell - Google Patents

Abstract

An end cap seal assembly (10) for an electrochemical cell such as an alkaline cell (8) comprises a convoluted end cap disk (40) which may also function as a cell terminal and an underlying insulating disk (20) also having a convoluted surface. The convoluted end cap disk (40) has a downwardly extending wall (45) with at least one aperture (48) therethrough which preferably faces the ambient environment. The insulating disk (20) has a downwardly extending wall (26) forming a rupturable membrane (23) which underlies and abuts the inside surface of the downwardly extending wall of the end cap. The rupturable membrane underlies and abuts the aperture (48) in the downwardly extending wall (45) of the end cap. When gas pressure within the cell exceeds a predetermined level the rupturable membrane (23) pushes through said aperture (48) and ruptures allowing gas to escape therefrom directly to the environment. A separate terminal plate (120) may be welded to a portion of the top surface of the convoluted end cap (40). The conductive layer of a film-laminate condition tester (155) may be connected to the terminal plate (120).

Description

ASSEMBLY OF END CAP SEAL FOR AN ELECTROCHEMICAL CELL DESCRIPTION OF THE INVENTION The invention is concerned with an end cap assembly for sealing electrochemical cells, in particular alkaline cells. The invention is concerned with break-away devices within the end cap assembly that allow gas to escape from the interior of the cell and with end cap assemblies that provide a good contact surface for condition testers integrated into the label for the cell. Conventional electrochemical cells, such as alkaline cells, are formed of a cylindrical box having an open end. After the contents of the cell are dispensed, the cell is closed by crimping or bending the edge of the box over the end cap assembly to provide a seal for the cell. The end cap assembly provides an exposed end cap plate that functions as a terminal of the cell and commonly a plastic insulating element that insulates the end cap plate from the cell housing, a problem associated with the design of several electrochemical cells, particularly alkaline cells, is the cell's tendency to produce gases as it is discharged beyond a certain point, usually around Ref: 123496 from the point of complete exhaustion of the useful capacity of the cell. Electrochemical cells, in particular alkaline cells, are conventionally provided with rupturable diaphragms or membranes within an end cap assembly for the cell housing. The diaphragm or rupturable membrane can be formed within a plastic insulating element as described for example in US Pat. No. 3,617,386. Such diaphragms are designed to break when the gas pressure inside the cell exceeds a predetermined level. The end cap assembly can be provided with ventilation holes so that the gas escapes when the diaphragm or membrane ruptures. The end cap assembly described in this reference uses considerable space above the rupturable diaphragm, which reduces the amount of space available within the cell for the active material. Also, the end cap assembly described in the reference is not designed to withstand radial compression forces and will tend to leak when the cell is subjected to extremes in hot and cold weather. In order to provide a watertight seal the prior art describes end box assemblies that include a metal support disc inserted between the end cap plate and an insulating element such as a plastic washer that electrically insulates the disc from metal support of the cell box. The metallic support disc can have a surface with many curves, as shown in US Patents 5,532,081 or 5,080,985 which ensures that the end cap assembly can withstand high radial compression forces during crimping or bending of the box edge. the cell around the end cap assembly. Such a support disc allows the radial forces to be maintained. This results in a strong mechanical seal around the end cap assembly at all times. Also, the prior art describes rupturable ventilation membranes that are integrally formed as part of an insulating element included within the end cap assembly. Such ventilation membranes are normally in the form of a rupturable disk that falls in a plane perpendicular to the longitudinal axis of the cell, for example as shown in U.S. Patent 4,537,841. As shown in this reference, the rupturable disc-shaped membrane is formed integrally as a thin portion that forms part of an insulating washer. Also, as shown in this reference, there is sufficient free space above the rupturable disk to allow the disk to break cleanly and allow gas to escape through it. The rupturable thin portion within the insulating element can also take the form of a circumferential ventilation membrane. formed integrally within the insulating washer as described in U.S. Patent 5, 080,985. The circumferential membrane forms the thin portion of the insulating washer. Such a membrane may have a ribbed edge to facilitate rupture of the membrane when the pressure of the gas within the cell exceeds a predetermined value. Such rupturable ventilation membranes, either disc-shaped or circumferential or in the form of thin grooved portions are characterized by being supported by a thicker, heavier structure of the insulating washer immediately surrounding the rupturable membrane portions. Recently condition testers for electrochemical cells, for example alkaline cells, have been integrated into the cell tag to form a combination or tag / tester compound that is attached to the cell box. The condition tester can usually be a thermochromic tester, but alternatively it can be an electrochromic tester, electrochemical tester, colorimetric tester or equivalent, which is attached to the interior surface of the tag. The condition tester may have an electrically conductive layer therein. When the ends of the conductive layer are pressed in contact with the terminals of the cell, the conductive layer arrives at an equilibrium temperature that is a function of the cell voltage. If the conductive layer becomes too hot it causes an electrochromic layer of the tester to change appearance, thereby giving the observer a visual indication of whether the cell is strong or weak. A combination or label / tester compound that employs a thermochromic type tester to be attached to the cell case is described in U.S. Patent Nos. 5,612,151 and 5,614,333. When the combination or tag / tester compound is to be applied to conventional alkaline cells, one end of the conductive layer must be either permanently electrically connected to the end cap or otherwise allowed to be manually pressed into contact electric with the end cap. In U.S. Patent 5,614,333 a label / tester embodiment is shown wherein one end of the conductive layer is designed to be manually pressed into contact with the end cap. That conducting end is separated from the terminal end cap by an electrically insulating layer having openings therethrough. To activate the tester, the leading end is manually pressed through these openings to contact the terminal end cap by applying pressure of the fingers to the label portion thereon. A ring can be inserted as a separate part between the peripheral edge of the terminal end cap and the cell housing to provide a contact platform for the conductive layer or conductors emanating therefrom, as described in the U.S. patent. 5,491,038. Alternatively, one end of the conductive layer of the tester can be permanently secured to the end cap of the cell using a conductive adhesive, as described in U.S. Patent 5,543,246. U.S. Patent Application Serial No. 08 / 897,918 filed July 21, 1997 discloses a terminal end plate with a non-uniform surface and having a flat portion to which the conductive layer of a condition tester integrated to the label for the cell. Thus, it is desirable to have an end cap assembly that provides a watertight seal for the cell, although the cell may be exposed to extremes in hot or cold weather and where the end cap assembly occupies a minimum amount of space within the cell. the cell, in such a way that additional active material can be added to the cell to increase capacity. It is also desirable to have a rupturable ventilation mechanism that occupies a minimum amount of space within the cell and that can be easily manufactured, such that ventilation is present at a predetermined pressure desired. It is desirable to have a terminal end cap with a portion of its structure surface that provides good electrical contact with the conductive portion of a label / tester compound or combination regardless of whether permanent or manual contact is desired. The invention is concerned with an electrochemical cell, for example an alkaline cell, comprising an end cap assembly or assembly inserted into the open end of a cylindrical housing for the cell. In one aspect, the end cap assembly comprises an end cap disc and an insulating disc element (insulating washer) underlying the end cap disc. The insulating disk electrically insulates the end cap of the cell housing. The disc of the end cap is formed of a one-piece metal construction having a surface with many curves. The disc of the end cap can be exposed and can function as a terminal of the cell. The disc of the end cap has a downwardly extending wall that extends down from a high point on the surface of the end cap and toward a lower portion on such a surface that is closer to the interior of the cell. The insulating disc has a surface with many curves. It has a thick region near the center that forms a protuberance and also a wall that extends downwards that extends down from a high point on the surface of the insulating disk and towards a lower point on the surface that is closest to the interior of the cell. The wall extending downwardly of the insulating disk is underlying and preferably spliced and brought into contact with a portion of the inner surface of the wall extending downward from the end cap. The wall extending downwardly of the disc of the end cap has at least one opening therethrough and a portion of the wall extending downwardly of the insulating disc forms a rupturable membrane which is connected to the opening in the disc of the end cap. Preferably, the rupturable membrane is contacted with a portion of the inner surface of the disk of the end cap immediately adjacent the opening. The opening and the underlying rupturable membrane can be visible from the outside of the cell. When the pressure of the gas within the cell reaches a predetermined level, the rupturable membrane underlying the opening is extruded through the opening and broken, thereby releasing the gas directly into the surrounding environment through such an opening. It is preferable to locate the rupturable membrane on a wall that extends down the insulating disk. However, the rupturable membrane could also be located on another portion of the insulating disk surface, for example, within a portion of the disk surface that falls perpendicular or at any other angle to the longitudinal axis of the cell, provided that the gas can pass unimpeded from the inside of the cell to the environment when the membrane ruptures. The end cap disc has a depressed central portion, preferably with a central opening therethrough. The surface of the end cap has two opposingly curved portions that form a pair of opposingly curved ribs one either on one end or the other of the wall extending downwardly of the disc of the end cap. The rib closest to the center of the insulating disk is curved outward, that is, convex and the other rib is inwardly curved, that is, concave. In another aspect, the end cap assembly has a similar construction but includes a separate end plate on the disc of the end cap with many curves mentioned above. The terminal plate can be welded to a portion of the end cap surface with many bends. The terminal plate desirably has a flat annular portion for connecting the conductive layer of an integrated condition tester to the label for the cell. There may be an insulating washer between the peripheral edge of the end plate and the peripheral edge of the cell case. As mentioned above, the disk of the end cap with many curves has a wall that extends downwardly with at least one opening therethrough and the insulating disk has at least one wall extending downwards which is connected to the wall. inner surface of the wall that extends down the disc of the end cap. A portion of the wall extending downwardly of the insulating disk forms a rupturable membrane that splices with the opening in the disk of the end cap. Preferably, the rupturable membrane is brought into contact with a portion of the inner surface of the disc of the end cap immediately adjacent to the opening. When the gas pressure inside the cell reaches a predetermined level, the rupturable membrane underlying the opening is extruded through the opening and broken, thereby releasing the gas directly to the surrounding environment through the opening. It is preferable to locate the rupturable membrane on a wall that extends down the insulating disk. However, the rupturable membrane could also be located on another portion of the insulating disk surface, for example, within a portion of the disk surface that falls perpendicular or at any other angle to the longitudinal axis of the cell, provided that the gas can pass unimpeded from the inside of the cell to the environment when the membrane ruptures. The invention will be better understood with reference to the drawings in which: Figure 1 is a perspective cut-away view of the end cap assembly of the invention. Figure 2 is an exploded view showing a preferred embodiment of the components of the end cap assembly. Figure 3 is a cross section of an alkaline cell containing an end cap assembly of the invention. Figure 4 is a cross section of another embodiment of the end cap assembly of the invention. A preferred structure of the end cap assembly or assembly 10 of the invention is illustrated in Figure 1. A specific embodiment of the end cap assembly 10 integrated with an alkaline cell 8 is illustrated in Figure 3. The lid assembly 10 at the end provides a seal for the open end of the box 70 of the cell and also has incorporated therein the cover 40 of the exposed end of the invention. The end cap 40 is in the form of a disk having a surface with many curves. The end cap 40 can function as one of the terminals of the cell (negative terminal for alkaline cell) as shown in Figure 3. The end cap 40 is also preferably of a structure that causes it to function as a radial spring . This allows the end cap assembly 10 to support high radial compression forces when the box 70 of the cell is bent around the end cap assembly and provides a hermetic seal even though the cell can be exposed to extremes at a cold room temperature or hot The end cap assembly 10 of the invention occupies less space within the cell than the conventional high compression end cap assemblies for alkaline cells. This allows the inclusion of additional anode and cathode active material to increase the capacity of the cell. The end cap assembly 10 of the invention, as best illustrated in FIGS. 1-3, consists of a disc 40 of the end cap, an electrically insulating member 20 and an elongate stream collector 60. The insulating element 20 is preferably in the form of an insulating disk (washer). The insulating disc 20 and the disc 40 of the end cap have an opening 92 and 82 respectively through their respective central portions for receiving a metal current collector 60. Preferably, the head of the current collector has a flange or flange 65 which acts as a seat for the base of the insulating disk 20.

Thus, during assembly, the current collector 60 of the end cap assembly can be inserted through the opening 92 of the insulating disk 20 until the flange 65 of the current collector comes to rest against the base of the central portion further of the disc 20 forming a protuberance 22. The end cap 40 is inserted over the insulating disc 20, such that the head 67a (Fig. 2) of the current collector 60 projects through the opening 82 of the end cap . The head 67a of the current collector is formed to fit through the opening 83 of the end cap 40 and then a protrusion 67 on the head 67a is formed, which is larger in diameter than the opening 82. The protrusion 67 may be formed by hammering the head 67a against the recessed central portion 41 of the end cap 40, after which the head 67a is inserted through the opening 82. The central portion 41 of the disc 40 of the end cap and the protrusion 22 of the insulating disk 20 are snapped together between the • boss 67 and flange 65 as best illustrated in Figure 1. Disk 40 of the end cap has many bends.

The end cap 40 preferably has many curves such as the shape best shown in FIGS. 1 and 2. It has a central portion 41 recessed with the central opening 82 therethrough. The central portion 41 forms a crater having a first wall 42 that extends upwards. The wall 42 terminates in a flat surface having curved edges forming the first annular rib 44, as illustrated in Fig. 3. A downwardly extending wall 45 extends from the outer circumferential edge of the first annular rib 44. wall 45 can be vertical, that is, parallel to the longitudinal axis 190 of the cell. Preferably the wall 45 extends outwardly at an angle between approximately 0 and 45 degrees from the vertical. The wall 45 (Figure 1) terminates in a curved surface 46a forming an annular depression defining the second annular curve rib 46. Wall 45 has at least one opening 48 therethrough. The opening 48 can be of various shapes, preferably circular, oval, rectangular or parallelepiped. The curved rib 46 terminates at the end flange 49, which forms the edge of the disc 40 of the end cap. The first and second annular ribs 44 and 46 respectively have opposite curvature. When viewed from the outside, the rib 44 of the cell is outwardly curved, that is, convex and the rib 46 is inwardly curved, this is concave, as illustrated in Figure 1. The opposing curved ribs 44 and 46 they end in the common wall 45 between them. The insulating disc 20 can be formed of a one-piece construction of plastic insulating material, preferably molded by injection molding of nylon 66, which is durable and corrosion resistant. As best illustrated in Figures 1 and 2, the insulating disk 20 has a central protrusion 22 with an opening through the center thereof. The protrusion 22 forms the thickest and heaviest portion of the disc. The peripheral edge of the protrusion 22 terminates in the first upwardly extending arm 23, which curves upwards (Figure 1) to form a first annular bend rib. The rib 25 ends in a wall 26 that extends downwards. The wall 26 preferably forms the. Angle angle with the longitudinal axis 190 as the wall 45 extending downwardly of the plate 40 of the end cap, such that the walls 25 and 45 are parallel to each other when the end cap assembly is formed. The wall 26 extending downward terminates in a curved bottom 27a forming the second annular curve rib 27. The rib 27 terminates at a peripheral edge 28 that extends upwardly, forming "the circumferential edge of the disc 20. The annular ribs 25 and 27 have opposite curvature When viewed from the outside of the cell, the annular rib 25 is outwardly curved, that is, convex and the annular rib 27 is curved inwards, that is, concave, as illustrated in Figure 1. During assembly, when the end cap 40 is inserted over the surface of the disc 20, the rib 25 fits within the curved area of the rib 44 and the rib 46 fits within the curved area of the rib 27, as shown in Fig. 1. Preferably, the wall 26 that is The downwardly extending insulating disk 20 falls flush against the inner surface of the wall 45 extending downwardly from the end cap 40. A small rupturable membrane portion 23 of the wall 26 lies below the opening 48 and is visible through the opening 48. The thickness of the rupturable portion 23 may be the same as the thickness of the wall 26 extending downwardly. or the thickness of the membrane portion 23 can be adjusted somewhat smaller or larger than the thickness of the remaining portion of the wall 26. The size of the opening 48 and the thickness of the underlying rupturable membrane 23 can be adjusted from the way that the membrane 23, will be extruded through the opening 48 and will break when the gas pressure inside the cell reaches a predetermined level. When the insulating disk and the integrally formed wall 26 are preferably formed of nylon 66, it has been determined that the thickness of the membrane 23 can advantageously be between about 0.05 mm and 0.40 mm and the diameter of the opening 48 can be between about 2.0 and 8.0 mm or the cross-sectional area of the opening 48 can be between about 3 mm square and 50 mm square. For cells of size AAAA, AAA, AA, C and D, a preferred wall thickness 26 is between about 0.30 mm and 0.80 mm. The preferred thickness of rupturable portion 23 is approximately between about 0.20 mm and 0.40 mm. With such thickness it has been determined that it is advantageous to adjust the opening to a circular configuration having a diameter between about 0.3 mm and 5.0 mm. Such a combination will allow the membrane portion 23 to be extruded through the opening 48 and rupture when the gas pressure inside the cell reaches a "level of approximately 56.2 Kg / cm square gauge (5.4 x 106 Pascais (800 pounds force per square inch gauge).) If the cell is an AA alkaline cell, the nylon membrane portion 66 may desirably have a thickness of about 0.3 mm and a circular opening 48 with a diameter of about 4 mm. combination, the membrane portion 23 will break when the gas pressure inside the cell reaches approximately 70.3 Kg / cm square gauge (6.75 x 106 Pascais (1000 pounds force / square inch gauge)). If the cell is an alkaline cell D, the portion 23 of nylon membrane 66 can desirably have a thickness of about 0.4 mm and a circular opening 48 with a diameter of about 8 mm. The membrane portion 23 will break when the gas pressure inside the cell reaches approximately 35.5 kg / square cm (3.38 x IO6 Pascais (500 pounds force / square inch gauge)). It should be appreciated that it is not proposed that the opening 48 be limited to any particular shape or other shapes, for example, square, oval, rectangular, parallelepiped or irregularly shaped having opposite, non-parallel sides, for example star shapes or triangle, for opening 48 are also appropriate. Such other configurations for the opening 48 may have width or cross-sectional area comparable to the circular configuration mentioned above. It should also be appreciated that while nylon 66 is a preferred material for insulating disc 20 and portion 23 of integral rupturable membrane, other materials, preferably a durable plastic material, permeable to hydrogen, resistant to corrosion, may also be appropriate in the present application. For example, the insulating disk 20 and rupturable membrane portion 23 can be formed of polypropylene, talc-filled polypropylene, sulfonated polyethylene or other grades of polyamide (nylon). The combination of the membrane thickness 23 and the size of the opening 48 can be adjusted depending on the material used and the level of gas pressure at which the rupture is designed. It has been determined appropriate to employ only one opening 48 and a corresponding rupturable membrane 23. However, the downwardly extending wall 45 can be provided with a plurality of openings of comparable size with a plurality of underlying rupturable membrane portions 23 integral with the wall 26 of size and thickness described above. This would provide additional assurance that the rupture of the membrane and ventilation would be presented at the desired gas pressure. It is preferable to have the rupturable membrane 23 pressed down against the lower surface of the wall 45 which extends downwards, so that it falls directly below the opening 48. It is preferable to locate the rupturable membrane 23 on the wall 26 extending downwardly of the insulating disk 20, since such location allows the gas to pass unobstructed from the cell to the environment when the cell is attached to another cell or a device to which energy is provided. However, the rupturable membrane 23 could also be located in another portion of the surface of the insulating disk, for example, within a flat portion of the surface of the disk, that is, oriented perpendicular to the longitudinal axis 190. Similarly, the opening 48 of splicing within the surface of the end cap through which the membrane ruptures could be located in another portion of the end cap 40, for example, on a portion of the surface 40 of the end cap perpendicularly oriented to the longitudinal axis 190. Such alternative locations are feasible provided that the gas can freely pass into the surrounding environment from such sites or locations even when the cell is connected to another cell or device that is energized. An advantage of the end cap assembly 10 of the invention is that the opening 48 provides a ventible passage for the gas to escape from the interior of the cell and at the same time provides a ventilation hole through which the gas can escape directly. to the environment. This eliminates the need for a separate vent hole to allow gas to escape from the end cap assembly once the membrane 23 breaks. Another advantage of the invention as illustrated in Figures 1-3 is that the disc 40 of the end cap functions as a cell terminal and metal support disc that can withstand high radial compression forces and in effect works as a radial spring, thereby ensuring an airtight seal regardless of whether the cell is exposed to extremes in hot and cold weather. The end cap assembly 10 of the invention is preferably inserted to the open end of an alkaline cell 150. A box of a representative alkaline cell case is shown in Figure 3. Such alkaline cells have a box (case) 70 cylindrical formed initially with one end 170 closed and the opposite end open. The alkaline cells have an anode consisting of zinc, a cathode consisting of manganese dioxide, a potassium hydroxide electrolyte and a separating material which usually consists of rayon or cellulose. After the cell is filled with active anode and cathode material, an end cap assembly 10 is ready for insertion to the open end to seal the cell. The construction materials for the box 70 can preferably be nickel-coated steel. The end cap 40 is constructed of a conductive metal that has good mechanical strength and corrosion resistance, such as cold-rolled steel coated with nickel or stainless steel, preferably low carbon steel coated with nickel. The insulating disc 20 and the integral rupturable membrane 23 can be composed of a durable, corrosion-resistant plastic, which is permeable to hydrogen and which, at an appropriate thickness, forms a rupturable membrane. The insulating disk 20 and the integral rupturable membrane 23 can be composed of a polyamide (nylon) preferably nylon 66. Alternatively, the insulating disk 20 and the membrane 23 can be composed of polypropylene, polypropylene filled with talc, sulfonated polyethylene or other grades of polyamide (nylon). The current collector 60 can be selected from a variety of known electrically conductive metals which are useful as current collector materials, for example brass, tin-coated brass, bronze, copper or indium-coated brass. In manufacturing, once the end cap 40 is secured to the insulating disc 20 by the current collector 60 to form the assembly 10 as described above, the assembly 10 can then be fitted to the open end of a cell box 70 full (figure 3). The end cap assembly 10 is inserted into the cell 8, such that the lower portion 28a of the peripheral edge 28 rests on the circumferential cord 75. The cord 75 is formed by a circumferential indentation on the surface of the box 70 of the cell, near the open end of the cell. The circumferential cord 75 provides a shelf on which the peripheral edge 28 of the insulating disc 20 can be supported. The peripheral edge 72 of the box 70 is crimped or bent over the peripheral edge 28 of the insulating disc 20 to secure the end cap assembly in place vertically, that is, to prevent it from moving in the direction of the longitudinal axis 190. The crimped or bent peripheral edge 72 forms the shoulder 72a of the cell along the fold line. Then, the end cap assembly 10 can be subjected to radial bend where a mechanical force is applied to the portion 71 (FIG. 3) of the cell housing above the cord 75. Such radial force can be applied when pushing a mold or die above the surface 71 of the edge 72 to the cord 75. Initially, the diameter of the box on the surface 71, above the cord 75, is greater than the diameter of the body of the box 77 under the cord 75 As radial force is applied, the surface 71 is compressed inward causing the peripheral edge 49 of the disc 40 of the end cap to bite the peripheral edge 28 of the insulating disc 20. As radial force is applied, the the curved surface of the end cap 40 allows the wall 45 extending downward from the end cap to flex inwardly such that the end cap 40 is radially compressed. The end cap 40 functions as a radial spring, that is, it maintains its radial compression and results in a hermetic seal although the cell can be subjected to extremes in cold or hot weather. Another embodiment of the invention is shown as the end cap assembly 12 in FIG. 4. The end cap assembly 12 comprises a separate terminal plate 120, end cap disk 40 with many bends, insulating disk 20, manifold current 60 and insulating washer 130. The structure and structural relationship of the end cap disc 40, insulating disk 20 and current collector 60 are essentially the same as shown and described with reference to the embodiment shown in Fig. 1. The plate terminal 120 functions as one of the terminals of the cell (negative terminal for alkaline cell) and is of a structure that allows a condition tester 155 to be electrically connected to it. The condition tester 155 is integrated to the tag 180 so that the cell forms a combination or composite of tester / tag 185 (Fig. 4). As described above, the wall 26 extending downwards from the insulating disc 20 is connected to the inner surface of the wall 45 which extends downwards from the end cap 40. As described above, there is a rupturable membrane portion 23 of the wall 26 that is extruded through the opening 48 in the wall 45 and breaks when the gas pressure inside the cell exceeds a predetermined level. However, in the alternative embodiment shown in Figure 4, a separate terminal plate 120 is welded to the elevated flat surface portion 43 of the disk 40 of the end cap. In this embodiment, the current collector 60 can only pass through the opening 82 in the protrusion 22 of the insulating disc 20 and through the opening 82 in the disc 40 of the end cap and preferably does not pass through any portion of the terminal plate 120. The terminal plate 120 is formed of a single plate or disk having a flat surface 122 extending from the center of the disk 120 to a point corresponding to the edge 43a of the flat surface 43, as shown in Figure 4. At that point, the surface 122 is bevelled downwardly by the downwardly extending wall 124, which terminates at a flat bottom surface 125 preferably parallel to the surface 122. The planar surfaces 122 and 125 may be perpendicular to the longitudinal axis of the plane. the cell. The flat surface 125 forms the peripheral edge of the terminal plate 120. An insulating washer 130, which can be formed of plastic or heavy paper or cardboard, is placed between the peripheral edge 125 of the terminal plate 120 and the peripheral edge 72 of the box 70, to electrically isolate the terminal plate 120 from the box 70. The washer 130 is preferably composed of plastic coated paper, for example polyethylene coated paper of overall thickness of between about 0.2 and 0.5 mm. The thickness mentioned above for the rupturable membrane 23 and size and shape of the opening 48 with respect to the embodiment shown in Figure 1 also applies to the embodiment shown in Figure 4. In general, the construction materials, structure and descriptions of size for the elements with similar numbers in Figure 4 can be the same as those described with respect to Figure 1. The end plate 120 can be of the same metal composition as the end cap 40, preferably rolled steel cold coated nickel or stainless steel. The embodiment shown in Figures 1 and 4 can accommodate a film-laminate condition tester for the cell. However, the embodiment shown in Figure 4 is particularly suitable for such an application, since it provides a flat conductive surface 125 adjacent the peripheral edge 72 of the box 70. Such surface provides a very appropriate contact point for film-like conductive layers. or other conductive elements emanating from the condition tester. Such a conductive element must be permanently connected to the terminal plate 120 or otherwise be in close proximity to the terminal plate 120, such that it can be manually depressed in contact therewith. A condition tester for a cell can be integrated into the tag 180 of the cell, such that it lies wedged between the tag and the box 70. The condition tester can preferably be a thermochromic tester for the cell, as described in U.S. Patent Nos. 5,612,151 or 5,614,333 incorporated herein by reference. Such a tester is schematically shown as tester 155 (Figure 4) integrated to the tag 180 that is wrapped around the cell. The tester 155 has an electrically conductive layer shown schematically as a conductive layer 158 (Figure 4). There is an electrically insulating layer (not shown) between the conductive layer 158 and the box 70. A detailed design for the tester 155 is described in the two above patent references. When the ends of the conductive layer 158 or conductors emanating therefrom are pressed into contact with the terminals of the cell, heat is generated through the conductive layer. (The term "conductive layer" as used herein and in the claims is intended to include an electrically conductive coating or conductive film., also as an electrically conductive coating or conductive film having conductors emanating from. the same.) The equilibrium surface temperature at any point along the conductive layer is a function of the density of wats (power consumed per unit of surface area of conductive layer). This in turn is a function of the cell voltage at the time of the tests. If the cell voltage is too high, the conductive layer will reach a sufficiently high equilibrium temperature to cause a color change or appearance of a superimposed thermochromic layer. This gives the observer a visual effect that allows him to determine if the cell is weak or strong. In such a tester, one end of the conductive coating may be in permanent electrical contact with the negative terminal 120 of the alkaline cell 8 (Figure 4).

Alternatively, one end of the conductive layer may be close to the terminal 120 but not actually in contact with the terminal, until finger pressure is applied to the portion of the label 180 superimposed on that end of the conductive layer. In any case, if the tester 155 is integrated to a label 180 applied to a conventional alkaline cell 8, it is preferable that the contact surface 125 (FIG. 4) for the conductive layer 158 at the negative terminal of the cell be flat. Other condition testers that are integrated into the cell tag may also be used with the present invention, as long as they have an electrically conductive layer that must be electrically connected to the terminal 120. For example, the tester may be an electrochemical tester. as described in U.S. Patent 5,339,024 or a colorimetric tester described in U.S. Patent 5,627,472. The label 180 with the underlying tester 155, that is the label / tester compound or combination 185 is preferably applied to the cell by applying the label around the box 70 of the cell and thermal shrinkage of the label 180 on the cells. projections 72a of the cell. It has been determined that when the contact surface 125 on the terminal plate 120 is flat, more useful surface on the terminal is available to contact the conductive layer 158 and contact becomes easier and more secure. This results in more efficient and reliable contact between the conductive layer 158 and the end cap terminal 120 if the tester is designed to be activated by applying a manual pressure of the fingers to the region 160 of the label on the end. end of the conductive layer or alternatively, if such end of the conductive layer is permanently welded to the terminal 120 of the end cap, on the contact surface 125. The components comprising the end cap assembly 12 shown in Fig. 4 can be assembled and crimped or bent within the open end of the cell as described above with respect to the end cap assembly 10 shown in Figs. 3, except that after the crimping or bending, the upper section 71 of the box 70 on and around the end cap 40 and insulating disk 20, a separate terminal plate 20 is welded to the end cap 40 and an insulating washer 130 is included between the terminal plate 120 and the peripheral edge 72 of the box 70. It is also possible to weld the terminal plate 120. to the end cap 40 and insert the washer 130 after the crimping or bending operation. Although the present invention has been described with respect to specific embodiments, it should be appreciated that variations in the concept of the invention are possible. Thus, the invention is not intended to be limited to the specific embodiments described herein, but will be defined by the claims and equivalents thereof. It is noted that, in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it refers.

Claims (38)

1. CLAIMS Having described the invention as above, it is claimed as property, contained in the following claims: 1. An improved electrochemical cell, which has a cylindrical box with open ends and an end cap assembly inserted therein that closes the box , the cell has a positive terminal and a negative terminal, the end cap assembly comprises an end cap and an electrically insulating sealing element, the insulating sealing element has an elongated, electrically conductive current collector that passes through from it, the current collector is in electrical contact with the end cap, the insulating sealing element electrically insulates the cap from the end of the box and the edge of the box is crimped or bent over the peripheral edge of the end cap To form a shoulder of the cell along the crimping or bending line, the improvement is characterized in that it comprises: End cap assembly comprising an end cap and an insulating seal element underlying the end cap when the cell is viewed in an upright position with the end cap assembly on top, wherein the insulating member electrically insulates the cap of the cap. At the end of the cell case, the end cap is formed of a one piece metal construction disc having a surface with many curves and at least one opening through its surface; the insulating element comprises an insulating disk having a surface with many curves, wherein a portion of its surface is subjacent to the opening in the disk of the end cap when the cell is observed in vertical position, with the cap assembly end above, the portion of the insulating disk underlying the opening forms a rupturable membrane, whereby, when the pressure of the gas within the cell reaches a predetermined level, the rupturable membrane penetrates through the opening and breaks, releasing by this the gas directly to the surrounding environment through the opening. The electrochemical cell according to claim 1, characterized in that the end cap is exposed to the environment and the end cap functions as a terminal of the cell. 3. The electrochemical cell according to claim 1, characterized in that the rupturable membrane is connected to the opening in the disc of the end cap. The electrochemical cell according to claim 1, characterized in that a portion of the rupturable membrane is brought into contact with the disc of the end cap in the region of a disc surface of the end cap immediately adjacent to the aperture . The electrochemical cell according to claim 1, characterized in that the insulating disk comprises a plastic material having a wall extending downwards, extending downwards from a high point on the surface of the insulating disk and towards a lower point on its surface that is closer to the inside of the cell when the cell is observed in vertical position, with the end cap assembly on top, the end cap disk has a wall extending downward extending down from a high point on the surface thereof when the cell is viewed in an upright position, with the end cap assembly on top, wherein the wall extending downwardly of the insulating disk is underlying at least a substantial portion of the wall extending downward from the end cap disc, wherein the at least one opening penetrates through the wall extending downwardly in the end cap disc, wherein a portion of the wall extending downwardly of the insulating disk forms a rupturable membrane underlying the opening, whereby when the pressure of the gas within the cell reaches a predetermined level, the rupturable membrane underlying the opening penetrates through the opening and ruptures, thereby releasing the gas directly to the surrounding environment through the opening. 6. The electrochemical cell according to claim 5, characterized in that the rupturable membrane is connected to the opening in the insulating disk. The electrochemical cell according to claim 5, characterized in that a portion of the rupturable membrane is brought into contact with the disc of the end cap in the region of a disc surface of the end cap immediately adjacent to the aperture. . The electrochemical cell according to claim 1, characterized in that the opening in the end cap has a cross-sectional area of between about 3 and 50 square mm and the rupturable membrane has a thickness between about 0.05 and 0.40 mm. The electrochemical cell according to claim 1, characterized in that the opening in the disc of the end cap is visible from the outside of the end cap assembly. 10. The electrochemical cell according to claim 5, characterized in that the surface of the disk of the end cap has a recessed central region. The electrochemical cell according to claim 10, characterized in that the end cap has an opening through the recessed central region and a portion of the current collector passes through the opening, the current collector has a portion of head seated on the upper surface of the recessed central region when the cell is observed in vertical position with the end cap assembly on top, wherein the diameter of the head portion is greater than the diameter of the opening through the region central oppressed. The electrochemical cell according to claim 11, characterized in that the insulating disk has a relatively thick region at its center, forming a protrusion and wherein the recessed central region of the end cap is pressed against the protuberance by means of the head of the current collector. 13. The electrochemical cell according to claim 12, characterized in that the current collector has a flange portion or flange that surrounds a portion of the body of the elongated current collector, wherein the flange or flange is connected to the lower surface of the electrode. the protrusion and wherein the recessed central region of the end cap disc is retained under pressure against the protrusion between the head of the current collector and the flange or flange. The electrochemical cell according to claim 10, characterized in that the disc of the end cap has two opposite curved surface portions forming a pair of annularly curved annular ribs, one of the annular ribs is curved outwards (convex) and the other is curved inward (concave) when the cell is observed in the vertical position with the end cap assembly on top, the rib curve outward (convex) is closer to the recessed central portion and the curved inward (concave) rib is closer to the peripheral edge of the end cap disc, where the wall that extends downward from the end cap disc forms a common wall between the pair of annular ribs. 15. An improved electrochemical cell, having an open-ended cylindrical box and an end cap assembly inserted therein that closes the box, the cell having a positive terminal and a negative terminal and a label around the box of the cell, the end cap assembly comprises a terminal element and an electrically insulating sealing element, the sealing element has an elongated, electrically conductive current collector passing therethrough, the current collector is in contact electrical with the terminal element, the insulating sealing element electrically insulates the end cap from the box and the edge of the box is crimped or bent over the peripheral edge of the end cap to form a cell shoulder along of the crimping or bending line, the improvement is characterized in that it comprises: the end cap assembly comprising a terminal plate that functions as a thermometer At the end of the cell, a disc of the one-piece metal construction end cap having a surface with many curves and at least one opening therethrough, the disc of the end cap is underlying the plate. terminal and a. insulating sealing element underlying the disc of the end cap when the cell is viewed in an upright position with the end cap assembly on top, wherein the insulating element electrically insulates the disc from the end cap of the cell housing; the insulating element comprises an insulating disk having a surface with many curves, wherein a portion of its surface is subjacent to the opening in the disk of the end cap when the cell is observed in vertical position with the end cap assembly above, the portion of the insulating disc is underlying the opening forming a rupturable membrane, whereby when the pressure of the gas within the cell reaches a predetermined level, the rupturable membrane penetrates through the opening and breaks, releasing by this the gas directly to the surrounding environment through the opening. 16. The electrochemical cell according to claim 15, characterized in that the rupturable membrane is connected to the opening in the disc of the end cap. The electrochemical cell according to claim 15, characterized in that a portion of the rupturable membrane is brought into contact with the disk of the end cap in the region of a disk surface of the end cap immediately adjacent to the aperture. . The electrochemical cell according to claim 15, characterized in that the insulating disk comprises a material having a downwardly extending wall extending downwards from a high point on the surface of the insulating disk and towards a lower point on its surface that is closest to the inside of the cell when the cell is viewed in an upright position with the end cap assembly on top, the end cap disk has a downwardly extending wall extending downward from a point high on the surface thereof when the cell is viewed in an upright position with the end cap assembly on top, wherein the wall extending downwardly of the insulating disk is underlying at least a substantial portion of the wall extending down the end cap disc, wherein the at least one opening penetrates through the wall which extends downwardly into the disk of the end cap, wherein a portion of the wall extending downwardly of the insulating disk forms a rupturable membrane underlying the the opening, whereby when the gas pressure reaches a predetermined level, the rupturable membrane underlying the opening penetrates through the opening and ruptures, thereby releasing the gas directly into the surrounding environment through the opening. 19. The electrochemical cell according to claim 18, characterized in that the rupturable membrane is connected to the opening in the disc of the end cap. The electrochemical cell according to claim 18, characterized in that a portion of the rupturable membrane is brought into contact with the end cap disc in the region of a disc surface of the end cap immediately adjacent to the aperture. . The electrochemical cell according to claim 18, characterized in that the terminal plate has a portion of its flat surface and at an angle approximately straight to the longitudinal axis of the cell and in proximity to the cell shoulder, the flat surface provides a electrical contact region for an electrically conductive layer of a condition tester for the cell. 22. The electrochemical cell according to claim 21, characterized in that at least a portion of the tester is attached to the inner surface of the label. 23. The electrochemical cell according to claim 21, characterized in that the flat portion of the terminal plate forms a circular annular tier. 24. The electrochemical cell according to claim 15, characterized in that a portion of the terminal plate is welded to the disk of the end cap. 25. The electrochemical cell according to claim 15, characterized in that the disk surface of the end cap has a recessed central region. The electrochemical cell according to claim 25, characterized in that the disc of the end cap has an opening through the recessed central region and a portion of the current collector passes through the opening, the current collector has a head portion seated on the upper surface of the recessed central region when the cell is viewed in an upright position with the end cap assembly on top, wherein the diameter of the head portion is greater than the diameter of the opening through of the recessed central region. 27. The electrochemical cell according to claim 26, characterized in that the insulating disk has a relatively thick region at its center and wherein the recessed central region of the end cap is retained under pressure against the protrusion by the head of the manifold of current. 28. The electrochemical cell according to claim 27, characterized in that the current collector has a flange portion or flange that surrounds a portion of the body of the elongated current collector, wherein the flange or flange is connected to the lower surface of the electrode. the protrusion and wherein the recessed central region of the end cap disc is retained under pressure against the protrusion between the head of the current collector and the flange or flange. 29. The end cap assembly according to claim 18, characterized in that the disc of the end cap has a recessed central portion and two opposingly curved surface portions that form a pair of opposingly curved annular ribs, one of the ribs. The rings are curved outward (convex) and the other is curved inward (concave) when the cell is observed in the vertical position, with the end cap assembly on top, the curved rib outward (convex) is closest to the lowered central portion and curved inward (concave) rib is closest to the peripheral edge of the end cap disc, wherein the wall extending downwardly of the disk of the end cap forms a common wall between the pair of annular ribs. 30. An end cap assembly for insertion into the open end of the cylindrical case of an alkaline cell, the end cap assembly is characterized in that it comprises a disc of the end cap and an insulating seal element underlying the cap of the end when the cell is observed in vertical position with the end cap assembly on top, where the insulating element electrically insulates the end cap of the cell housing; the disk of the end cap is of a one-piece metal construction having a surface with many curves and at least one opening through its surface; the insulating element comprises an insulating disk having a surface with many curves, wherein a portion of its surface is subjacent to the opening in the disk of the end cap when the cell is observed in vertical position with the end cap assembly above, the portion of the insulating disk underlying the opening forms a rupturable membrane, whereby, when the pressure of the gas within the cell reaches a predetermined level the rupturable membrane penetrates through the opening and breaks thereby releasing the gas directly to the surrounding environment through the opening. 31. The end cap assembly according to claim 30, characterized in that the disc of the end cap is exposed to the environment and the end cap disc functions as a terminal of the cell. 32. The end cap assembly according to claim 30, characterized in that the rupturable membrane is connected to the opening in the disc of the end cap. The end cap assembly according to claim 30, characterized in that a portion of the rupturable membrane is brought into contact with the disc of the end cap in the region of a disc surface of the immediately adjacent end cap. to the opening. The end cap assembly according to claim 30, characterized in that the insulating disk comprises a plastic material having at least one downwardly extending wall extending downwards from a high point on the surface of the insulating disc and towards a lower point on its surface that is closer to the inside of the cell when the cell is observed in vertical position with the end cap assembly on top, the disc of the end cap has at least one wall that it extends downwards, which extends downwards from a high point of the surface of the same when the cell is observed in vertical position with the end cap assembly on top, where the wall extending downward from the insulating disk is underlying at least a substantial portion of the wall extending downwardly of the disk of the end cap, wherein the at least one opening penetrates through the wall. to the wall extending downwardly on the disk of the end cap, wherein a portion of the wall extending downwardly of the insulating disk forms a rupturable membrane underlying the opening, whereby, when the pressure of the gas within of the cell reaches a predetermined level, the rupturable membrane underlying the opening penetrates through the opening and ruptures, thereby releasing the gas directly to the surrounding environment through the opening. 35. The end cap assembly according to claim 34, characterized in that the rupturable membrane portion is connected to the opening in the disc of the end cap. 36. The end cap assembly according to claim 34, characterized in that a portion of the rupturable membrane is brought into contact with the disc of the end cap in the region of a disc surface of the immediately adjacent end cap. to the opening. 37. The end cap assembly according to claim 34, characterized in that the rupturable membrane has a thickness between about 0.05 mm and 0.40 mm and the opening through which it penetrates during the rupture has a cross-sectional area of between approximately 3 and 50 square mm. 38. The end cap assembly according to claim 34, characterized in that the disc of the end cap has a recessed central portion and two opposingly curved surface portions that form a pair of oppositely curved annular ribs., one of the annular ribs is curved outward (convex) and the other is curved inward (concave) when the cell is observed in the vertical position, with the end cap assembly on top, the rib curved outward (convex) is closer to the recessed central portion and the curved inward (concave) rib is closer to the peripheral edge of the end cap disc, where the wall extending downward from the end cap disc forms a wall common between the pair of annular ribs. SUMMARY OF THE INVENTION An end cap seal assembly (10) for an electrochemical cell is described, such as an alkaline cell (8) comprising an end cap with many curves (40), which can also function as a cell terminal and an underlying insulating disk (20) which also has a surface with many curves. The disc (40) of the end cap, with many curves, has a wall extending downwards (45) with at least one opening therethrough which is preferably facing the surrounding environment. The insulating disc (20) has a downwardly extending wall (26) which forms a rupturable membrane (23) which is underlying and abuts the inner surface of the wall extending downwardly from the end cap. The rupturable membrane is underlying and is connected to the opening (48) in the wall extending downwards (45) of the end cap. When the gas pressure inside the cell exceeds a predetermined level, the rupturable membrane (23) pushes through the opening (48) and breaks, allowing the gas to escape therefrom directly into the environment. A separate terminal plate (120) can be welded to a portion of the top surface of the end cap (40) with many bends. The conductive layer of a condition tester (155)