JP6045848B2 - Flat battery - Google Patents

Description

  The present invention relates to a flat battery such as a coin battery.

  Conventionally, a flat battery including a bottomed cylindrical outer can and a sealing can disposed so as to cover the opening of the outer can is known. In such a flat battery, for example, as disclosed in Patent Document 1, in order to maintain airtightness inside the battery and to ensure electrical insulation between the outer can and the sealed can, A gasket made of resin is arranged at the connecting part. That is, a gasket sandwiched between the outer can and the outer can is disposed on the peripheral wall portion of the sealed can.

  The battery disclosed in Patent Document 1 is a coin-type lithium battery having a high battery height (thickness).

JP 2007-2000593 A

  By the way, in the coin-type lithium battery as disclosed in Patent Document 1, since the height of the battery is high, a configuration in which the peripheral wall portion of the sealing can is increased is conceivable. However, in general, since the sealed can is formed by drawing, it is difficult to manufacture a peripheral wall portion having a high height.

  Further, as disclosed in Patent Document 1, the height of the peripheral wall portion of the sealing can is lowered, and the bulging portion protruding from the outer can and the positive electrode ring at the substantially central portion in the height direction of the outer can. The structure which receives the surrounding wall part and gasket of the said sealing can by part is considered. However, in such a configuration, since the sealing force between the outer can and the sealing can is weakened, there is a possibility that sufficient sealing performance cannot be obtained.

  Further, as disclosed in Patent Document 1, when the gasket is attached to the peripheral wall portion by folding the peripheral wall portion of the sealing can, the thickness of the gasket and the peripheral wall portion is increased by the amount of folding the peripheral wall portion of the sealing can. . Therefore, the internal volume of the battery is reduced accordingly.

  An object of the present invention is to obtain a configuration capable of improving the sealing performance of a gasket in a flat battery in which a gasket is injection-molded on a peripheral wall portion of a sealing can with a simple, easy manufacturing and compact configuration. .

  A flat battery according to an embodiment of the present invention includes a bottomed cylindrical outer can having a cylindrical side wall portion extending in a cylindrical axis direction, and a peripheral wall portion extending in the cylindrical axis direction. A bottomed cylindrical sealing can covering the opening of the outer can so as to be positioned inside the outer can, and formed by injection molding on a peripheral wall portion of the sealing can, and sandwiched between the outer can and the sealing can And a gasket. The peripheral wall portion of the sealing can extends in the cylindrical axis direction without the tip portion being folded back. The gasket is formed integrally with the covering portion formed on the peripheral wall portion so as to cover at least a part of the peripheral wall portion of the sealing can, and is formed integrally with the covering portion in the cylinder axis direction. And a protruding portion located outward. The protrusion has a protrusion length in the cylindrical axis direction that is greater than the thickness of the protrusion (first configuration).

  Thereby, the front end portion of the peripheral wall portion of the sealing can extends in the cylinder axis direction without being folded back, and in the configuration in which the gasket is injection-molded on the peripheral wall portion, the length of the peripheral wall portion in the cylinder axis direction is shortened. However, the sealing performance can be improved by the gasket.

  That is, the protruding portion protruding from the peripheral wall portion of the sealing can in the gasket is greatly deformed because the protruding length in the cylinder axis direction is larger than the thickness of the protruding portion. As a result, the deformation range of the gasket can be increased and the reaction force generated in the gasket can be increased compared to the configuration in which the protruding length in the tube axis direction is equal to or less than the thickness of the protruding portion. The surface pressure between the two can be increased. Therefore, the sealing performance can be improved by the gasket. Moreover, since the length of the surrounding wall part of a sealing can becomes short by the length in the said cylinder axis direction of a protrusion part, the surrounding wall part of this sealing can can be formed easily.

  In the first configuration, it is preferable that the protruding portion has a protruding length in the cylinder axis direction larger than a thickness at a tip portion of the protruding portion (second configuration).

  Thereby, the front-end | tip part can be deform | transformed more largely by pressing the front-end | tip part of the protrusion part of a gasket strongly with respect to an exterior can. Therefore, the sealing performance of the gasket can be further improved.

  In the first or second configuration, it is preferable that the protruding portion has a protruding length in the cylinder axis direction that is 1/4 or more than a length of the gasket in the cylinder axis direction (third) Configuration).

  Thereby, the protrusion length of the cylinder axial direction in the protrusion part of a gasket can be lengthened compared with the protrusion length (1/9 or less with respect to the length of the gasket axial direction of a gasket) of a general structure. . Therefore, the length of the peripheral wall portion of the sealing can in the cylinder axis direction can be shortened more reliably, and the sealing performance by the gasket can be more reliably improved.

  In any one of the first to third configurations, in the gasket, a thickness of a portion of the covering portion that covers an outer side of the peripheral wall portion of the sealing can is directed toward a tip portion of the peripheral wall portion. It is preferable that the taper is gradually reduced (fourth configuration).

  Thus, in the gasket formed in the taper shape, the thickness of a gasket can be made as small as possible by applying the above-mentioned 1st to 3rd structure. That is, when the gasket is formed in a taper shape, it is necessary to ensure a thickness of the gasket equal to or greater than a predetermined value at the tip portion of the peripheral wall portion of the sealing can positioned in the gasket. For this reason, it is necessary to increase the thickness of the gasket at the proximal end portion of the peripheral wall portion of the gasket so that a predetermined thickness or more of the gasket thickness can be secured at the distal end portion of the peripheral wall portion.

  By reducing the length of the peripheral wall portion of the sealing can in the cylinder axis direction as in the first to third configurations described above, the thickness of the proximal end portion of the peripheral wall portion of the gasket is reduced accordingly. Can do. Therefore, the thickness of the entire gasket can be reduced.

  In any one of the first to fourth configurations, the outer can and the sealing can each have a bottomed cylindrical shape, and the cylindrical side wall portion of the outer can has an outer diameter, It is preferable that the height in the cylinder axis direction in a state where the outer can and the sealed can are combined is smaller than four times (fifth configuration).

  As described above, when the outer diameter of the outer can is smaller than four times the height in the cylinder axis direction in a state where the outer can and the sealing can are combined, the entire battery is compared with a general coin-type battery. The height of becomes higher. Even in such a battery, by applying the above first to third configurations, the length of the peripheral wall portion of the sealing can can be shortened, and the sealing performance by the gasket can be improved. Further, in the battery configuration as described above, even when the taper is formed as in the fourth configuration, the thickness of the entire gasket can be reduced.

  The said 5th structure WHEREIN: The said cylindrical side wall part of the said exterior can has the outer diameter 2 times or less with respect to the height of the said cylinder axial direction in the state which combined the said exterior can and the said sealing can. Is preferable (sixth configuration).

  As described above, the first to third configurations described above are applied even when the outer diameter of the outer can is not more than twice the height in the cylinder axis direction in a state where the outer can and the sealed can are combined. Thus, the length of the peripheral wall portion of the sealing can can be shortened, and the sealing performance by the gasket can be improved.

  In the flat battery according to the embodiment of the present invention, the distal end portion of the peripheral wall portion of the sealing can is extended without being folded back, and a gasket is injection-molded on the peripheral wall portion. In this gasket, the protruding length of the protruding portion protruding from the peripheral wall portion is larger than the thickness of the protruding portion. Thereby, the sealing performance by a gasket can be improved, shortening the length of the surrounding wall part of a sealing can.

FIG. 1 is a cross-sectional view showing a schematic configuration of a flat battery according to an embodiment of the present invention. FIG. 2 is a partially enlarged cross-sectional view showing the structure of the electrode body in the flat battery in an enlarged view. FIG. 3 is a partially enlarged cross-sectional view showing an enlarged protrusion of the gasket. FIG. 4 is a cross-sectional view showing the dimensions of each part of the battery. FIG. 5 is a diagram showing a state when a gasket is molded on the negative electrode can. FIG. 6 is an enlarged sectional view showing the gasket in an enlarged manner.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated.

(overall structure)
FIG. 1 is a cross-sectional view showing a schematic configuration of a flat battery 1 according to an embodiment of the present invention. The flat battery 1 is sandwiched between a positive electrode can 10 as a bottomed cylindrical outer can, a negative electrode can 20 as a sealing can covering the opening of the positive electrode can 10, and the positive electrode can 10 and the negative electrode can 20. And the electrode body 40 housed in a space formed between the positive electrode can 10 and the negative electrode can 20. Therefore, the flat battery 1 is formed into a flat coin shape by combining the positive electrode can 10 and the negative electrode can 20 together. In the space formed between the positive electrode can 10 and the negative electrode can 20 of the flat battery 1, in addition to the electrode body 40, a non-aqueous electrolyte (not shown) is also enclosed. The battery case is configured by combining the positive electrode can 10 and the negative electrode can 20.

  The positive electrode can 10 is made of a metal material such as stainless steel, and is formed into a bottomed cylindrical shape by press molding. The positive electrode can 10 includes a circular bottom portion 11 and a cylindrical peripheral wall portion 12 (cylindrical side wall portion) formed continuously with the bottom portion 11 on the outer periphery thereof. The peripheral wall portion 12 is provided so as to extend substantially vertically from the outer peripheral end of the bottom portion 11 in a longitudinal sectional view (the state illustrated in FIG. 1). As will be described later, the positive electrode can 10 is crimped to the negative electrode can 20 by folding the opening end side of the peripheral wall portion 12 inside the positive electrode can 10 with the gasket 30 sandwiched between the positive electrode can 20 and the negative electrode can 20. It has been. Note that the symbol P in FIG. 1 is the cylinder axis of the positive electrode can 10. The peripheral wall portion 12 extends in the cylinder axis direction of the positive electrode can 10.

  Similarly to the positive electrode can 10, the negative electrode can 20 is made of a metal material such as stainless steel and is formed in a bottomed cylindrical shape by press molding. The negative electrode can 20 has a substantially cylindrical peripheral wall portion 22 whose outer shape is smaller than that of the peripheral wall portion 12 of the positive electrode can 10, and a circular plane portion 21 that closes one of the openings. Similar to the positive electrode can 10, the peripheral wall portion 22 is also provided so as to extend substantially perpendicular to the flat portion 21 in a longitudinal sectional view. The peripheral wall portion 22 extends in the cylinder axis direction P without being folded back at the tip portion. That is, the negative electrode can 20 is a so-called straight can in which the peripheral wall portion 22 is not folded back.

  Further, the peripheral wall portion 22 is formed with an enlarged diameter portion 22b whose diameter is increased stepwise as compared with the base end portion 22a on the flat surface portion 21 side. That is, the peripheral wall portion 22 is formed with a step portion 22c between the base end portion 22a and the enlarged diameter portion 22b. As shown in FIG. 1, the open end side of the peripheral wall portion 12 of the positive electrode can 10 is bent and caulked with respect to the step portion 22c. That is, the positive electrode can 10 has the opening end side of the peripheral wall portion 12 fitted to the step portion 22 c of the negative electrode can 20. The peripheral wall portion 22 of the negative electrode can 20 also extends in the cylinder axis direction, like the peripheral wall portion 12 of the positive electrode can 10.

  The outer diameter D of the peripheral wall portion 12 of the positive electrode can 10 is preferably smaller than 4 with respect to the thickness T of the flat battery 1. In particular, D / T is preferably 2 or less. Thus, the flat battery 1 of this embodiment is higher in height than a general coin battery (D / T is 4 or more). The outer diameter D and the thickness T are the dimensions of the portion shown in FIG.

  Further, with respect to the thickness T of the flat battery 1, the battery shoulder portion (the peripheral wall portion 12 is caulked to the peripheral wall portion 22 of the negative electrode can 20 from the bottom portion 11 of the positive electrode can 10 to the opening portion of the peripheral wall portion 12. The distance t to the end position is preferably in the range of 0.8 to 0.9. Thus, as described above, the peripheral wall portion 12 of the positive electrode can 10 is caulked at a position close to the flat surface portion 21 of the negative electrode can 20 even in the case of a battery having a height higher than that of a general coin-type battery. Therefore, when the positive electrode can 10 is caulked against the negative electrode can 20, deformation of the peripheral wall portion 22 of the negative electrode can 20 can be suppressed.

  The gasket 30 is made of polypropylene (PP). The gasket 30 is molded on the peripheral wall portion 22 of the negative electrode can 20 so as to be sandwiched between the peripheral wall portion 12 of the positive electrode can 10 and the peripheral wall portion 22 of the negative electrode can 20. The detailed configuration of the gasket 30 will be described later. The material of the gasket 30 is not limited to PP, and a resin composition containing an olefin elastomer in polyphenylene sulfide (PPS), polytetrafluoroethylene (PFA), a polyamide resin, or the like may be used.

  As shown in FIG. 2, the electrode body 40 is formed by laminating a plurality of substantially disc-like positive electrodes 41 and substantially disc-like negative electrodes 46 accommodated in a bag-like separator 44 in the thickness direction. Do it. Thereby, the electrode body 40 has a substantially columnar shape as a whole. In addition, the electrode body 40 has a plurality of positive electrodes 41 and negative electrodes 46 stacked so that both end faces are negative electrodes.

  As shown in FIG. 2, the positive electrode 41 is formed by arranging positive electrode active material layers 42 containing a positive electrode active material such as lithium cobaltate on both surfaces of a positive electrode current collector 43 made of a metal foil such as aluminum.

  As shown in FIG. 2, the negative electrode 46 is formed by disposing negative electrode active material layers 47 containing a negative electrode active material such as graphite on both surfaces of a negative electrode current collector 48 made of a metal foil such as copper. The negative electrodes located at both axial ends of the substantially cylindrical electrode body 40 are only on one surface side of the negative electrode current collector 48 so that the negative electrode current collectors 48 are located at the axial end portions of the electrode body 40, respectively. Has a negative electrode active material layer 47. That is, the negative electrode current collectors 48 are exposed at both ends of the substantially cylindrical electrode body 40. One negative electrode current collector 48 of the electrode body 40 is positioned on the bottom portion 11 of the positive electrode can 10 via the positive electrode current collector 43 and the insulating sheet 49 (see FIGS. 1 and 2). The other negative electrode current collector 48 of the electrode body 40 abuts on the flat portion 21 of the negative electrode can 20 in a state where the electrode body 40 is disposed between the positive electrode can 10 and the negative electrode can 20 (see FIG. 1). .

  The separator 44 is a bag-shaped member formed in a circular shape in plan view, and is formed in a size that can accommodate the substantially disc-shaped positive electrode 41. The separator 44 is constituted by a microporous thin film made of polyethylene having excellent insulating properties. Thus, by forming the separator 44 with a microporous thin film, lithium ions can pass through the separator 44. The separator 44 is formed by wrapping the positive electrode 41 with a single sheet of a rectangular microporous thin film and bonding the overlapping portions of the sheet material by thermal welding or the like.

  As shown in FIGS. 1 and 2, the positive electrode current collector 43 of the positive electrode 41 is integrally formed with a conductive positive electrode lead 51 extending outward from the positive electrode current collector 43 in a plan view. The positive electrode current collector 43 side of the positive electrode lead 51 is also covered with the separator 44. A positive electrode current collector 43 that is not provided with the positive electrode active material layer 42 is disposed between the insulating sheet 49 and the bottom 11 of the positive electrode can 10. That is, the positive electrode current collector 43 is in electrical contact with the bottom 11 of the positive electrode can 10.

  The negative electrode current collector 48 of the negative electrode 46 is integrally formed with a conductive negative electrode lead 52 extending outward from the negative electrode current collector 48 in plan view.

  As shown in FIGS. 1 and 2, the positive electrode 41 and the negative electrode 46 are such that the positive electrode lead 51 of each positive electrode 41 is located on one side and the negative electrode lead 52 of each negative electrode 46 is on the opposite side of the positive electrode lead 51. Laminated so as to be positioned.

  As described above, with the plurality of positive electrodes 41 and the negative electrodes 46 laminated in the thickness direction, the plurality of positive electrode leads 51 are overlapped with each other in the thickness direction and connected by ultrasonic welding or the like. Accordingly, the plurality of positive electrodes 41 are electrically connected to each other via the plurality of positive electrode leads 51, and each positive electrode 41 and the positive electrode can 10 are electrically connected to each other. On the other hand, the plurality of negative electrode leads 52 are also connected to each other by ultrasonic welding or the like with the distal end side overlapped in the thickness direction. Accordingly, the plurality of negative electrodes 46 are electrically connected to each other via the plurality of negative electrode leads 52, and each negative electrode 46 and the negative electrode can 20 are electrically connected to each other.

(Gasket configuration)
Next, the structure of the gasket 30 is demonstrated in detail using FIG.1, FIG.3, FIG.4 and FIG.

  As shown in FIGS. 1 and 4, the gasket 30 is formed in a substantially cylindrical shape so as to wrap around the peripheral wall portion 22 of the negative electrode can 20. Specifically, the gasket 30 is molded on the negative electrode can 20 so as to cover the inner side of the negative electrode can of the peripheral wall portion 22 and the outer side of the negative electrode can of the step portion 22c and the enlarged diameter portion 22b of the peripheral wall portion 22. Molded. The gasket 30 is provided so as to protrude from the opening side of the peripheral wall portion 22 in the cylinder axis direction of the negative electrode can 20. That is, the gasket 30 includes a covering portion 31 that covers the peripheral wall portion 22 of the negative electrode can 20, and a protruding portion 32 that is located on the outer side in the cylinder axis direction of the negative electrode can 20 with respect to the peripheral wall portion 22 of the negative electrode can 20.

  As shown in FIGS. 1 and 4, the gasket 30 has an inner diameter that is substantially flush with the inner surface of the base end portion 22 a of the peripheral wall portion 22 of the negative electrode can 20. That is, the covering portion 31 and the protruding portion 32 of the gasket 30 have the same inner diameter.

  As shown in FIG. 6, the gasket 30 is formed in a tapered shape in which the outer diameter gradually decreases from the covering portion 31 located on the proximal end side of the peripheral wall portion 22 of the negative electrode can 20 toward the tip of the protruding portion 32. ing. That is, the gasket 30 is formed in a tapered shape in the covering portion 31 so that the thickness gradually decreases from the proximal end side to the distal end side of the peripheral wall portion 22 of the negative electrode can 20. In the gasket 30 formed in such a taper shape, it is necessary to secure a thickness of the gasket 30 at a predetermined (X in FIG. 6) or more at the tip portion of the peripheral wall portion 22 of the negative electrode can 20. Therefore, the thickness on the proximal end side of the peripheral wall portion 22 in the gasket 30 needs to be Y larger than X. In such a configuration, as described later, the thickness Y can be made as small as possible by shortening the length of the peripheral wall portion 22 and increasing the protruding length of the protruding portion 32 of the gasket 30. Therefore, the thickness of the gasket 30 can be reduced, and the battery capacity in the flat battery can be increased as much as possible.

  The gasket 30 has such a length as to contact the bottom portion 11 of the positive electrode can 10 in a state where the peripheral wall portion 12 of the positive electrode can 10 is caulked on the outer peripheral side of the negative electrode can 20. Thereby, when the positive electrode can 10 is caulked against the negative electrode can 20, the tip portion of the protrusion 32 of the gasket 30 is pressed against the bottom 11 of the positive electrode can 10. Thereby, the space formed by the positive electrode can 10 and the negative electrode can 20 is sealed by the tip portion of the protruding portion 32 of the gasket 30.

  Further, as described above, the gasket 30 is compressed by the open end side of the peripheral wall portion 12 of the positive electrode can 10 by caulking the open end side of the peripheral wall portion 12 of the positive electrode can 10 to the outer peripheral side of the negative electrode can 20. The Therefore, the gasket 30 seals between the peripheral wall portion 12 of the positive electrode can 10 and the outer peripheral side of the negative electrode can 20.

  The pressing force of the tip end portion of the protruding portion 32 of the gasket 30 against the bottom portion 11 of the positive electrode can 10 is obtained by the force received by the gasket 30 when the peripheral wall portion 12 of the positive electrode can 10 is caulked to the outer peripheral side of the negative electrode can 20. .

  In the protruding portion 32 of the gasket 30, the length Q in the cylinder axis direction of the negative electrode can 20 is equal to the length in the cylinder axis direction of the covering portion 31 that covers the peripheral wall portion 22 of the negative electrode can 20.

  Further, as shown in FIG. 3, the protruding portion 32 of the gasket 30 has a length Q in the cylindrical axis direction that is larger than the dimension in the thickness direction corresponding to the radial direction of the negative electrode can 20 (the thickness of the protruding portion 32). . In particular, it is preferable that the protruding portion 32 of the gasket 30 has a length Q in the cylindrical axis direction that is larger than the dimension S in the thickness direction at the tip portion of the protruding portion 32.

  As described above, the protrusion 32 that does not cover the peripheral wall portion 22 of the negative electrode can 20 in the gasket 30 has a long shape in the cylinder axis direction of the negative electrode can 20, so that the protrusion 32 can be easily deformed. it can. Thus, as described above, the gasket 30 provided on the peripheral wall portion 22 of the negative electrode can 20 is pressed by the opening end portion of the peripheral wall portion 12 of the positive electrode can 10, whereby the protruding portion 32 of the gasket 30 and the outer can 10. It is possible to more securely seal the space between the bottom 11 of the two.

  In addition, since the length of the entire gasket 30 in the cylinder axis direction is larger than that in the conventional case, the positive electrode can 10 and the negative electrode can 20 can be sealed by the gasket 30 in a wide range. Thereby, it can prevent more reliably that a liquid leak etc. arise from the clearance gap between the positive electrode can 10 and the negative electrode can 20. FIG.

  The gasket 30 preferably has a length Q of the protruding portion 32 in the cylinder axis direction that is ¼ or more of the length of the gasket 30 in the cylinder axis direction. Thereby, the length of the protruding portion 32 in the cylinder axial direction is set to be longer than the length of the protruding portion of the gasket in the flat battery having a general configuration (less than 1/9 of the length of the gasket in the cylindrical axis direction) Can be long. Thereby, while being able to shorten the length of the peripheral wall part 22 of the negative electrode can 20 in the cylinder axis direction more reliably, the sealing performance by the gasket 30 can be improved more reliably.

  As will be described later, the gasket 30 is formed by so-called injection molding in which a molten resin material is injected into a mold and molded. An injection portion 33 is located on the protrusion 32 of the gasket 30 corresponding to an injection port for injecting a molten resin material into the mold. That is, the injection part 33 is formed by an injection port for injecting a resin material into the mold when the gasket 30 is injection-molded.

  The injection part 33 has a concave part 33a formed when the convex part 30a (see FIG. 5) formed by the injection port is removed. That is, as will be described later, a protrusion 30a from which resin protrudes is formed on the protrusion 32 of the gasket 30 by the injection port of the mold. The convex portion 30a is removed by a part of the molding die when the gasket 30 is taken out from the molding die. Therefore, the root portion of the convex portion 30a is removed, and the concave portion 33a as described above is formed.

  Thus, by injecting the resin material to the portion where the protrusion 32 of the gasket 30 is formed, the peripheral wall portion 22 of the negative electrode can 20 is prevented from being deformed by the resin material injected into the mold. it can. Further, with the above-described configuration, it is possible to prevent the peripheral wall portion 22 of the negative electrode can 20 from hindering the injection of the resin material into the mold.

  Furthermore, since the injection part 33 has the recessed part 33a formed in the surface at the side of the positive electrode can 10 of the protrusion part 32, as shown in FIG.1 and FIG.3, the state which crimped the positive electrode can 10 with respect to the negative electrode can 20 Thus, a gap 35 is formed between the peripheral wall portion 12 of the positive electrode can 10 and the gasket 30. In the gap 35, the electrolytic solution or the like that has entered between the protruding portion 32 of the gasket 30 and the bottom portion 11 of the positive electrode can 10 is accumulated. Therefore, the gap 35 can prevent leakage of the electrolyte solution or the like in the flat battery 1.

  As described above, the protrusion 32 of the gasket 30 has a length corresponding to the cylinder axis direction of the negative electrode can 20 larger than the dimension in the thickness direction. Thereby, in the molding die of the gasket 30, an injection port for injecting the resin material can be easily provided in a portion forming the peripheral wall portion 12 side of the protruding portion 32.

(Manufacturing method of flat battery)
Next, a method for manufacturing the flat battery 1 having the above-described configuration will be described.

  First, the bottomed cylindrical positive electrode can 10 and negative electrode can 20 are each formed by press molding.

  On the other hand, a plurality of plate-like positive electrodes 41 covered with a separator 44 and a plurality of plate-like negative electrodes 46 are laminated in the thickness direction to form a substantially cylindrical electrode body 40 as shown in FIG. Since the electrode body 40 is manufactured by a method similar to the conventional method, the detailed manufacturing method will not be described.

  The manner in which the gasket 30 is molded on the negative electrode can 20 will be described with reference to FIG.

  As shown in FIG. 5, a fixed mold 61, a movable mold 62, and a piston movable mold 63 having a ring-shaped cross section are arranged outside the negative electrode can 20, and pins 64 are arranged inside the negative electrode can 20. To place. Accordingly, a space 60 for forming the gasket 30 is formed around the peripheral wall portion 22 of the negative electrode can 20 by the molds 61, 62, 63 and the pins 64. Accordingly, the fixed mold 61, the movable mold 62, the piston movable mold 63, and the pin 64 constitute a mold for molding the gasket 30.

  The fixed mold 61 is provided with an inlet 61 a for injecting a resin material from the outside into the space 60. By injecting a molten resin material into the space 60 from the injection port 61a, the space 60 is filled with the resin material. At this time, since the injection port 61a of the fixed mold 61 is provided at a position where the peripheral wall portion 22 of the negative electrode can 20 does not exist, when the resin material is injected from the injection port 61a, it hits the peripheral wall portion 22 and the peripheral wall portion. It is possible to prevent the deformation of 22. In addition, the peripheral wall portion 22 can prevent the flow of the resin material from being hindered.

  After the resin material in the space 60 is cured and the gasket 30 is molded, first, the movable mold 62 is removed. Then, the negative electrode can 20 in which the gasket 30 is molded is removed from the pin 64 and the fixed mold 61 by moving the piston movable mold 63 in the axial direction of the pin 64 (the direction of the white arrow in FIG. 5). Can be separated.

  As shown in FIG. 5, the gasket 30 has a protrusion 30 a that protrudes into the injection port 61 a of the fixed mold 61 in a state where the gasket 30 is formed of a resin material in the space 60. The convex portion 30 a is cut by the fixed mold 61 when the gasket 30 is moved in the direction of the white arrow in FIG. 5 with respect to the fixed mold 61 as described above. At this time, since the gasket 30 made of a resin material such as PP is removed so that only the projecting portion 30a is not cut away cleanly, it is removed on the surface of the gasket 30 as shown in FIGS. A concave portion 33a is formed.

  Here, the fixed mold 61 is formed in a taper shape such that the portion that molds the outer surface of the cylindrical gasket 30 gradually increases in inner diameter toward the step portion 22 c of the peripheral wall portion 22 of the negative electrode can 20. ing. Thereby, when the gasket 30 is pushed by the piston movable mold 63 as described above, the negative electrode can 20 can be easily detached from the fixed mold 61.

  Therefore, as shown in FIG. 6, the gasket 30 has a shape in which the outer diameter gradually decreases from the covering portion 31 positioned on the proximal end side of the peripheral wall portion 22 of the negative electrode can 20 toward the distal end of the protruding portion 32. .

In the positive electrode can 10, the electrode body 40 is disposed together with the insulating sheet 47 and the like, and a non-aqueous electrolyte is injected. Then, the negative electrode can 20 in which the gasket 30 is molded as described above is disposed so as to cover the opening of the positive electrode can 10. In this state, the opening end side of the peripheral wall portion 12 of the positive electrode can 10 is bent and crimped inward of the positive electrode can 10 with respect to the step portion 22 c of the peripheral wall portion 22 of the negative electrode can 20. Thereby, the flat battery 1 of the above-mentioned structure is obtained. Here, the nonaqueous electrolytic solution can be obtained, for example, by dissolving LiPF ₆ in a solvent obtained by mixing ethylene carbonate and methyl ethyl carbonate.

(Effect of embodiment)
In this embodiment, the gasket 30 formed on the peripheral wall portion 22 of the negative electrode can 20 includes a covering portion 31 that covers the peripheral wall portion 22 and a protruding portion 32 that protrudes from the covering portion 31 in the cylindrical axis direction of the negative electrode can 20. And have. The protrusion 32 has a protrusion length Q in the cylinder axis direction that is larger than a dimension S in the thickness direction.

  Thereby, since the length of the surrounding wall part 22 of the negative electrode can 20 can be shortened, this surrounding wall part 22 can be formed easily. Since the protrusion 32 of the gasket 30 is likely to be deformed, the gasket 30 can be easily deformed by pressing the gasket 30 against the bottom 11 of the outer can 10. Therefore, as compared with the configuration in which the protruding length Q of the protruding portion 32 of the gasket 30 is equal to or less than the dimension S in the thickness direction, the range in which the gasket 30 is deformed can be expanded and the reaction force generated by the deformation in the gasket 30 is increased. Thus, the surface pressure between the gasket 30 and the positive electrode can 10 can be increased. Therefore, the sealing performance by the gasket 30 can be improved.

  Moreover, the gasket 30 has a shape such that the outer diameter gradually decreases from the covering portion 31 located on the proximal end side of the peripheral wall portion 22 of the negative electrode can 20 toward the distal end of the protruding portion 32. In such a shape of the gasket 30, the thickness of the gasket 30 can be made as thin as possible by shortening the peripheral wall portion 22 of the negative electrode can 20 and increasing the protruding length of the protruding portion 32 of the gasket 30.

  Further, since the resin material is injected into the projecting portion 32 of the gasket 30, the peripheral wall portion 22 of the negative electrode can 20 is deformed by the injection of the resin material, or the flow of the resin material is inhibited by the peripheral wall portion 22. Can be prevented.

(Other embodiments)
Although the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit thereof.

  In the said embodiment, the gasket 30 is formed in the taper shape in which an outer diameter becomes small as it goes to the front-end | tip part of the protrusion part 32. As shown in FIG. However, the gasket 30 may be formed in a cylindrical shape. Moreover, you may form in the taper shape contrary to the said embodiment.

  In the embodiment, the outer diameter D of the peripheral wall portion 12 of the positive electrode can 10 is smaller than 4 with respect to the thickness T of the flat battery 1. However, the outer diameter D of the peripheral wall portion 12 of the positive electrode can 10 may be 4 or more with respect to the thickness T of the flat battery 1.

  In the embodiment, the distance t from the bottom 11 of the positive electrode can 10 to the battery shoulder in the peripheral wall 12 is 0.8 to 0.9 with respect to the thickness T of the flat battery. However, t / T may be smaller than 0.8 or larger than 0.9.

  In the said embodiment, although the electrode body 40 is set as the structure which laminated | stacked the some positive electrode 41 and the negative electrode 46 alternately, the structure of an electrode body may be other than this.

  In the embodiment, the positive electrode can 10 is an outer can and the negative electrode can 20 is a sealed can. Conversely, the positive electrode can may be a sealed can and the negative electrode can may be an outer can.

  In the embodiment, the positive electrode can 10 and the negative electrode can 20 are each formed in a bottomed cylindrical shape, and the flat battery 1 is formed in a coin shape. However, the flat battery is not limited thereto, and the flat battery 1 You may form in shapes other than column shape.

  The flat battery according to the present invention can be used for a flat battery in which a gasket is formed into a sealed can.

1: flat battery, 10: negative electrode can (sealing can), 12: peripheral wall part, 20: positive electrode can (exterior can), 22: peripheral wall part (tubular side wall part), 30: gasket, 31: covering part, 32 : Protruding part

Claims (5)

A bottomed cylindrical outer can having a cylindrical side wall extending in the cylinder axis direction;
A bottomed cylindrical sealing can that covers the opening of the outer can so as to have a peripheral wall portion extending in the cylindrical axis direction, and the peripheral wall portion is positioned inside the outer can;
A gasket formed by injection molding on a peripheral wall of the sealing can and the gasket Ru Tei sandwiched between the outer can by said sealing can,
With
The peripheral wall portion of the sealing can extends in the cylindrical axis direction without the tip portion being folded back,
The gasket is
A covering portion formed on the peripheral wall portion so as to cover at least a part of the peripheral wall portion of the sealing can;
A protrusion that is formed integrally with the covering portion and is located outward in the cylinder axis direction with respect to the peripheral wall portion ;
Have
The gasket is formed in a tapered shape in which the thickness of the portion covering the outer side of the peripheral wall portion of the sealing can in the covering portion gradually decreases toward the tip portion of the peripheral wall portion,
The protrusion, the protruding length of the cylinder axis direction, much larger than the thickness of the protrusion,
The protrusion has an injection part formed corresponding to an injection port of a molding die used for injection molding of the gasket,
The injection portion has a recess formed on the surface of the protrusion.
Flat battery. The flat battery according to claim 1,
The protruding portion is a flat battery in which a protruding length in the cylindrical axis direction is larger than a thickness at a tip portion of the protruding portion. The flat battery according to claim 1 or 2,
The protruding portion is a flat battery in which a protruding length in the cylinder axis direction is ¼ or more of a length of the gasket in the cylinder axis direction. The flat battery according to any one of claims 1 to 3 ,
Each of the outer can and the sealed can is a bottomed cylindrical shape,
The cylindrical side wall portion of the outer can is a flat battery whose outer diameter is smaller than four times the height in the cylindrical axis direction in a state where the outer can and the sealing can are combined. The flat battery according to claim 4 ,
The cylindrical side wall portion of the outer can is a flat battery whose outer diameter is not more than twice the height in the cylindrical axis direction in a state where the outer can and the sealing can are combined.

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