JP5486356B2 - Flat battery - Google Patents

Description

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

  2. Description of the Related Art Conventionally, a flat battery including a bottomed cylindrical outer can and a sealing can that is disposed so as to cover the opening of the outer can and is connected to the outer can on the outer peripheral side is known. In such a flat battery, for example, as disclosed in Patent Documents 1 and 2, in order to maintain airtightness inside the battery and to ensure electrical insulation between the outer can and the sealing can, A resin gasket is arranged at the connection with the can.

  Patent Documents 1 and 2 disclose a configuration in which the gasket is molded on the peripheral wall portion of the sealing can. In particular, Patent Document 2 discloses a configuration in which a gasket is molded on a peripheral wall portion of a bottomed cylindrical sealing can so as to extend from an open end portion to a flat portion.

JP-A-4-34837 JP-A 61-233965

  By the way, in the case of a flat battery, the connection between the outer can and the sealing can is generally performed by fitting the open end of the outer can to the step formed on the peripheral wall portion of the sealing can. As in the configuration disclosed in Patent Documents 1 and 2, when a resin gasket is molded around the peripheral wall portion of the sealing can, the opening end portion of the outer can is attached to the end portion of the peripheral wall portion of the sealing can. At the time of fitting, a compression force is applied to the gasket molded in the sealing can in the cylindrical axis direction of the sealing can.

  Then, in the configuration in which the gasket is molded so as to extend from the opening end portion to the flat portion inside the sealing can as in the configuration of Patent Document 2, the compression force applied to the gasket causes the other portion on the flat portion side of the sealing can. There is a possibility that a part of the gasket formed thinner than the part peels from the inner surface of the sealed can. In this way, when a part of the gasket is peeled off, depending on the internal structure of the battery, a short circuit may occur between the electrode body and the sealing can, or the peeled gasket may damage the electrode body inside the battery. There is sex.

  Here, in the flat battery having the configuration of Patent Document 2, since the opening end side of the peripheral wall of the sealing can fitted with the outer can is a simple plate shape, the sealing performance is relatively low and the fitting is performed. The compression force generated in On the other hand, in order to increase the internal volume of the flat battery and improve the sealing performance, a step portion was formed on the peripheral wall portion of the sealing can, and the opening end portion of the outer can was fitted to the step portion. In this case, a very large compressive force is applied in the cylinder axis direction of the sealed can. Therefore, in this case, there is a very high possibility that a part of the gasket formed thinner than other portions will be peeled off.

  An object of the present invention is to obtain a configuration that prevents the gasket from peeling from the inner surface of the sealing can in a flat battery in which the gasket is molded so as to extend from the opening end of the sealing can to the flat portion.

  A flat battery according to an embodiment of the present invention includes a bottomed cylindrical outer can, a cylindrical portion having an outer shape smaller than a side wall of the outer can, and a flat portion that closes one opening of the cylindrical portion. And a sealing can disposed in an inverted dish shape with respect to the outer can so as to form a space between the outer can and at least the inner side of the sealing can from the opening end of the cylindrical portion. A gasket that is molded over a flat surface portion, and the cylindrical portion of the sealing can is provided with a step portion that expands the opening end side of the cylindrical portion in a step shape. The opening end of the side wall is fitted to the step portion of the sealing can, and the gasket has a thickness of the gasket on the inner side of the sealing can on the opening end side of the cylindrical portion of the sealing can. Smaller than the thickness of the gasket on the inner side of the sealing can in the portion (first configuration).

  When the opening end portion of the side wall of the outer can is fitted to the step portion provided in the cylindrical portion of the sealing can, a force in the compression direction is applied to the gasket through the step portion. The above-described configuration can prevent the flat portion side of the sealing can of the gasket from being peeled off from the inner surface of the sealing can. That is, the gasket molded inside the cylindrical portion of the sealed can has a thickness on the inner side of the sealed can at the opening end side of the cylindrical portion of the sealed can, and a thickness on the inner side of the sealed can at the stepped portion of the sealed can. Therefore, the opening end side of the cylindrical portion of the sealed can is less rigid and easily deforms. Thereby, the force of the compression direction which a gasket receives is absorbed by the opening end side of the cylinder part of the sealing can in this gasket, and is hardly transmitted to the plane part side of the sealing can in this gasket. Therefore, it can prevent that the flat part side of the sealing can in a gasket peels from this sealing can.

  In the first configuration, the gasket includes a gasket on the inner side of the sealing can on the opening end side of the cylindrical portion between the stepped portion on the inner side of the sealing can and the opening end of the cylindrical portion. It is preferable that a step portion having a thickness smaller than the thickness of the gasket inside the sealing can in the step portion is provided (second configuration).

  Thereby, in the gasket, the thickness of the portion positioned on the opening end side of the cylindrical portion with respect to the stepped portion is smaller than the thickness of the portion positioned on the stepped portion side of the sealing can with respect to the stepped portion. Therefore, with the above-described configuration, the first configuration can be more reliably realized.

  In the first or second configuration, the gasket is preferably formed in a tapered shape such that a surface on the inner side of the sealing can is closer to the cylindrical portion toward the opening end of the cylindrical portion ( Third configuration).

  Thereby, when the gasket is molded, the mold can be easily pulled out inside the gasket, and the workability at the time of molding can be improved. Moreover, when arranging the components in the space formed between the outer can and the sealing can, the components can be easily arranged inward of the gasket from the opening end side of the cylindrical portion of the sealing can. It is possible to improve workability during battery assembly.

  In any one of the first to third configurations, the sealing can is formed with an R portion for connecting the planar portion and the cylindrical portion with a curved surface at an outer peripheral edge portion of the planar portion. The gasket preferably has a thickness such that a portion on the flat surface side of the sealing can reaches the flat portion of the sealing can from the R portion (fourth configuration).

  By carrying out like this, it can prevent more reliably that the part by the side of the flat part of the sealing can in a gasket peels from this sealing can. Since the R portion is formed on the outer peripheral side of the flat portion of the sealing can, if the end portion of the gasket is located only in the R portion, the end portion is easily peeled off. However, by forming the end portion of the gasket so as to reach the flat portion as in the above-described configuration, the end portion can be made difficult to peel from the sealing can.

  In any one of the first to fourth configurations, a positive electrode and a negative electrode formed in a plate shape are alternately arranged in a thickness direction in a space formed between the outer can and the sealed can. It is preferable that an electrode body laminated on the substrate is disposed (fifth configuration).

  In this way, when the electrode body has a laminated structure of the positive electrode and the negative electrode, if a part of the gasket molded on the inner surface of the sealing can is peeled off, a short circuit may occur between the electrode body and the sealing can. . Therefore, by applying the first to fourth configurations, it is possible to effectively prevent a short circuit from occurring between the electrode body and the sealing can.

  According to the flat battery according to the embodiment of the present invention, when the outer can and the sealing can are fitted, the force applied to the gasket molded in the sealing can is determined by the cylindrical portion of the sealing can in the gasket. Absorption is possible on the open end side. Thereby, it can prevent that the plane part side of the sealing can of a gasket peels from the inner surface of this sealing can.

  In addition, the gasket inner work surface and the battery assembly work are formed by tapering the inner surface of the gasket can into the tube portion toward the opening end of the tube portion of the seal can. Can improve the performance.

  Furthermore, by making the flat portion side of the sealing can of the gasket reach a flat portion of the flat portion of the sealing can, the flat portion side of the sealing can of the gasket can be more reliably separated from the sealing can. Can be prevented.

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 the structure of the peripheral wall portion of the sealing can (positive electrode can) in cross section. FIG. 4 is a cross-sectional view showing a schematic configuration of a sealing can (positive electrode can). FIG. 5 is a diagram illustrating a state in which the electrode body is configured. FIG. 6 is a cross-sectional view showing a configuration of an outer can (negative electrode can) before caulking into a sealed can (positive electrode can). FIG. 7 is a view showing a state when a gasket is molded on a sealing can (positive electrode can).

  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 includes a negative electrode can 10 as a bottomed cylindrical outer can, a positive electrode can 20 as a sealing can covering the opening of the negative electrode can 10, an outer peripheral side of the negative electrode can 10, and an outer periphery of the positive electrode can 20. A gasket 30 disposed between the electrode can 40 and an electrode body 40 accommodated in a space formed between the negative electrode can 10 and the positive electrode can 20. Therefore, the flat battery 1 is formed into a flat coin shape by combining the negative electrode can 10 and the positive electrode can 20 together. In the space formed between the negative electrode can 10 and the positive 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 negative 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 negative electrode can 10 includes a circular bottom portion 11 and a cylindrical peripheral wall portion 12 (side wall) 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 negative electrode can 10 is crimped to the positive electrode can 20 by bending the opening end side of the peripheral wall portion 12 inward with a gasket 30 sandwiched between the negative electrode can 20 and the positive electrode can 20. The negative electrode can 10 is formed with R portions each having a curved surface in a portion bent by press molding (for example, a portion between the bottom portion 11 and the peripheral wall portion 12).

  Similarly to the negative electrode can 10, the positive electrode can 20 is also made of a metal material such as stainless steel, and is formed into a bottomed cylindrical shape by press molding. The positive electrode can 20 has a cylindrical peripheral wall portion 22 (cylindrical portion) whose outer shape is smaller than that of the peripheral wall portion 12 of the negative electrode can 10 and a circular planar portion 21 that closes one of the openings. Similar to the negative electrode can 10, the peripheral wall portion 22 is also provided so as to extend substantially perpendicular to the plane portion 21 in a longitudinal sectional view. The peripheral wall portion 22 is formed with an enlarged diameter portion 22b whose diameter is increased stepwise compared to 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 negative electrode can 10 is bent and caulked with respect to the step portion 22c. That is, the negative electrode can 10 is fitted with the step 22 a of the positive electrode can 20 at the opening end side of the peripheral wall portion 12. In addition, the positive electrode can 20 is also formed with an R portion having a curved surface in a portion bent by press molding (for example, a portion between the flat portion 21 and the peripheral wall portion 22 or a step portion 22c). Has been.

  The gasket 30 is made of polypropylene (PP). The gasket 30 is molded on the peripheral wall portion 22 of the positive electrode can 20 so as to be sandwiched between the peripheral wall portion 12 of the negative electrode can 10 and the peripheral wall portion 22 of the positive 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 cylindrical 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.

  The positive electrode 41 is obtained 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.

  The negative electrode 46 is configured 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 ends in the axial direction of the substantially cylindrical electrode body 40 are arranged on one surface side of the negative electrode current collector 48 so that the negative electrode current collectors 48 are located at the axial ends of the electrode body 40, respectively. Only the negative electrode active material layer 47 is provided. 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 contacts the bottom 11 of the negative electrode can 10 in a state where the electrode body 40 is disposed between the negative electrode can 10 and the positive electrode can 20. The other negative electrode current collector 48 of the electrode body 40 is positioned on the flat surface portion 21 of the positive electrode can 20 via the insulating sheet 49.

  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.

  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.

  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 FIG. 1, the positive electrode 41 and the negative electrode 46 are such that the positive electrode lead 51 of each positive electrode 41 is positioned on one side and the negative electrode lead 52 of each negative electrode 46 is positioned on the opposite side of the positive electrode lead 51. Is laminated.

  As described above, in the state where the plurality of positive electrodes 41 and the negative electrodes 46 are laminated in the thickness direction, the plurality of positive electrode leads 51 are overlapped in the thickness direction on the tip side, and are applied to the flat portion 21 of the positive electrode can 20 by ultrasonic welding or the like. Connected. As a result, the plurality of positive electrodes 41 and the flat portion 21 of the positive electrode can 20 are electrically connected via the plurality of positive electrode leads 51. 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. Thereby, the plurality of negative electrodes 46 are electrically connected to each other via the plurality of negative electrode leads 52.

  In the electrode body 40 configured as described above, contact between the positive electrode 41 and the negative electrode can 10 or contact between the negative electrode 46 and the positive electrode can 20 may occur. Therefore, in this embodiment, the gasket 30 is provided on the inner surface of the peripheral wall portion 22 of the positive electrode can 20 that is positioned inward of the peripheral wall portion 12 of the negative electrode can 10. The gasket 30 prevents a short circuit between the electrode body 40 and the negative electrode can 10 and a short circuit between the electrode body 40 and the positive electrode can 20.

(Gasket configuration)
As shown in FIGS. 1 to 3, the gasket 30 is formed in a substantially cylindrical shape so as to wrap around the peripheral wall portion 22 of the positive electrode can 20. Specifically, the gasket 30 is molded on the positive electrode can 20 so as to cover the inner side of the peripheral wall portion 22 and the outer side of the stepped portion 22c and the enlarged diameter portion 22b of the peripheral wall portion 22. Molded. That is, the gasket 30 includes a gasket inner portion 31 that covers the inside of the positive electrode can of the peripheral wall portion 22, a gasket outer portion 32 that covers the outer portion of the peripheral wall portion 22, and a gasket that covers the tip of the open end of the peripheral wall portion 22. And a distal end portion 33.

  As shown in an enlarged view in FIG. 3, the gasket outer side portion 32 becomes thinner toward the opening end of the peripheral wall portion 22 of the positive electrode can 20. As shown in FIGS. 1 and 2, when the negative electrode can 10 is caulked against the positive electrode can 20, the stepped portion 22 c side of the peripheral wall portion 22 in the gasket outer portion 32 is formed on the peripheral wall portion 12 of the negative electrode can 10. Compressed by the open end. As described above, by reducing the thickness of the gasket outer side 32 on the opening end side of the peripheral wall portion 22 of the positive electrode can 20, the material cost of the gasket 30 can be reduced correspondingly, and if the outer dimensions do not change, the battery The capacity can be increased.

  As shown in FIG. 1, the gasket tip 33 has the opening end of the peripheral wall portion 22 of the positive electrode can 20 and the negative electrode in a state where the peripheral wall portion 12 of the negative electrode can 10 is caulked to the peripheral wall portion 22 of the positive electrode can 20. It is sandwiched between the bottom 11 of the can 10.

  Therefore, the step 22c side of the peripheral wall 22 in the gasket outer portion 32 and the gasket tip 33 serve as a seal that separates the space formed between the positive electrode can 20 and the negative electrode can 10 from the external space. Function.

  As shown in FIG. 3, the gasket inner portion 31 is formed in a substantially cylindrical shape from the lower surface of the flat portion 21 of the positive electrode can 20 to the opening end side of the peripheral wall portion 22 of the positive electrode can 20. As a result, the gasket inner portion 31 is positioned in the positive electrode can inside the positive electrode can of the base end portion 22a of the peripheral wall portion 22, and in the positive electrode can inside of the step portion 22c and the enlarged diameter portion 22b of the peripheral wall portion 22. And a gasket lower part 31b. Further, the gasket inner portion 31 is formed in a tapered shape as a whole so that the inner diameter becomes larger toward the opening end side of the peripheral wall portion 22 of the positive electrode can 20, that is, the inner surface approaches the peripheral wall portion 22. .

  The gasket upper portion 31 a is formed to have a thickness such that the end portion on the flat portion side of the positive electrode can 20 reaches the flat portion of the flat portion 21 from the R portion 23 between the flat portion 21 and the peripheral wall portion 22. That is, a part of the end portion of the gasket upper portion 31 a on the flat portion side is in close contact with the flat portion of the flat portion 21. Thereby, even if a force is applied to the gasket upper portion 31 a, it is possible to suppress the gasket upper portion 31 a from moving away from the positive electrode can 20 by the flat portion side of the gasket upper portion 31 a that is in close contact with the flat portion 21. it can.

  The gasket lower portion 31b is formed so that the inner surface thereof is located radially outward of the positive electrode can 20 from the inner surface of the gasket upper portion 31a. That is, an inner surface step portion 31c (step portion) is formed on the gasket upper portion side of the gasket lower portion 31b so that the diameter of the inner surface of the gasket upper portion 31a is larger than the diameter of the inner surface of the gasket lower portion 31b. The inner surface step portion 31c is formed in a taper shape whose inner diameter gradually increases from the gasket upper portion 31a toward the gasket lower portion 31b. Further, the inner surface step portion 31 c is formed so as to be positioned between the step portion 22 c of the peripheral wall portion 22 of the positive electrode can 20 and the opening end of the enlarged diameter portion 22 b. Thereby, as shown in FIG. 3, in the gasket lower part 31b, the positive electrode can inner side of the enlarged diameter portion 22b is larger than the thickness (B in FIG. 3) of the portion located on the inner side of the positive electrode can of the step portion 22c. The thickness of the portion located at (A in FIG. 3) is smaller.

  With such a configuration, when the flat battery 1 is manufactured, when the opening end of the peripheral wall portion 12 of the positive electrode can 10 is caulked to the step portion 22c of the positive electrode can 20, the compressive force generated by the caulking is generated. It can be absorbed by the gasket lower part 31b. That is, as will be described in detail later, when the negative electrode can 10 is caulked to the positive electrode can 20, if a compressive force is applied to the step portion 22c of the positive electrode can 20, it is also compressed to the gasket lower portion 31b via the step portion 22c. Force acts. At this time, in the gasket lower portion 31b, the thickness is smaller than the portion located on the inner side of the positive electrode can of the step portion 22c (in this embodiment, the inner surface step portion 31c), on the inner side of the positive electrode can of the enlarged diameter portion 22b. The located part is deformed. Thereby, the force which acts on the gasket lower part 31b when the negative electrode can 10 and the positive electrode can 20 are fitted can be absorbed by the gasket lower part 31b.

  Therefore, when the negative electrode can 10 is caulked to the positive electrode can 20, it is possible to suppress the force applied to the gasket lower portion 31b from being transmitted to the gasket upper portion 31a. Therefore, peeling of the gasket upper part 31a from the positive electrode can 20 due to deformation of the gasket upper part 31a can be prevented.

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

  First, the negative electrode can 10 shown in FIG. 6 and the positive electrode can 20 shown in FIG. 4 are respectively formed by press molding.

  On the other hand, a plurality of plate-like positive electrodes 41 covered with the 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. At this time, the negative electrode without the negative electrode active material layer 47 is disposed on both end faces in the axial direction of the electrode body 40 so that the negative electrode current collector 48 is exposed. As described above, in a state where the plurality of positive electrodes 41 and the negative electrodes 46 are laminated, the negative electrode leads 52 of the respective negative electrodes 46 are overlapped on the tip side and connected to each other by ultrasonic welding or the like. On the other hand, the positive electrode lead 51 of each positive electrode 41 is connected to the flat portion 21 of the positive electrode can 20 in which the gasket 30 is molded as described below by ultrasonic welding or the like in a state where the positive electrode leads 51 are overlapped with each other on the tip side.

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

  As shown in FIG. 7, a stationary mold 61, a movable mold 62, and a piston movable mold 63 having a ring-shaped cross section are arranged outside the positive electrode can 20, and pins 64 are arranged inside the positive electrode can 20. To place. As a result, a space for forming the gasket 30 is formed around the peripheral wall portion 22 of the positive electrode can 20 by the molds 61, 62, 63 and the pins 64. A resin is injected into the space from the outside and cured.

  After the resin is cured and the gasket 30 is molded, first, the movable mold 62 is removed. Then, by moving the piston movable mold 63 in the axial direction of the pin 64 (in the direction of the white arrow in FIG. 7), the positive electrode can 20 in which the gasket 30 is molded is removed from the pin 64 and the fixed mold 61. Can be separated.

  Here, the fixed mold 61 is formed in a taper shape such that the portion that forms the outer peripheral surface of the gasket outer portion 32 gradually increases in inner diameter toward the step portion 22 c of the peripheral wall portion 22 of the positive electrode can 20. Yes. Thus, when the gasket tip 33 is pushed by the piston movable mold 63 as described above, the positive electrode can 20 can be easily detached from the fixed mold 61.

  Further, a stepped portion 64 a corresponding to the inner stepped portion 31 c of the gasket inner portion 31 is formed on the outer surface of the pin 64. Further, the pin 64 is formed in a tapered shape that tapers toward the tip so that the inner diameter of the gasket inner portion 31 gradually increases toward the opening end of the peripheral wall portion 22 of the positive electrode can 20. Thereby, the positive electrode can 20 can be smoothly detached from the pin 64.

The positive electrode can 20 in which the gasket 30 is molded as described above is disposed so that the flat surface portion 21 is on the lower side, and the positive electrode lead 51 of each positive electrode 41 is superimposed on the flat surface portion 21. Connect by ultrasonic welding. Thereafter, a non-aqueous electrolyte is injected into the positive electrode can 20. And the negative electrode can 10 is covered so that the opening of the positive electrode can 20 may be covered. Thereafter, the opening end portion of the peripheral wall portion 12 of the negative electrode can 10 is bent and crimped inward by the step portion 22 c of the peripheral wall portion 22 of the positive 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.

  As described above, when the open end portion of the peripheral wall portion 12 of the negative electrode can 10 is caulked to the step portion 22c of the peripheral wall portion 22 of the positive electrode can 20, a large force is applied to the step portion 22c. Therefore, a large compressive force is applied to the gasket lower portion 31b through the step portion 22c. However, as described above, the gasket lower portion 31b is formed at the opening end portion of the enlarged diameter portion 22b rather than the thickness (B in FIG. 3) of the step portion 22c of the positive electrode can 20 on the inner side of the positive electrode can. Since the thickness of the inner side portion (A in FIG. 3) is smaller, the smaller thickness portion can be deformed to efficiently absorb the compressive force.

  Therefore, when the gasket lower part 31b is compressed as mentioned above, it can suppress that force is transmitted to the gasket upper part 31a. Thereby, it can prevent that this gasket upper part 31a peels from the inner surface of the positive electrode can 20. FIG.

  Moreover, the flat portion side of the positive electrode can 20 in the gasket upper portion 31 a is formed to have a thickness that reaches not only the R portion 23 but also the flat portion of the flat portion 21. As a result, even when a force that separates the gasket upper portion 31a from the peripheral wall portion 22 of the positive electrode can 20 is applied, the gasket upper portion 31a is caused to adhere by the adhesion force or frictional force between the gasket upper portion 31a and the flat portion of the flat portion 21. It can prevent peeling from the inner surface of the positive electrode can 20. That is, the gasket upper portion 31 a is less likely to peel from the inner surface of the positive electrode can 20 than when the gasket upper portion 31 a is attached only to the R portion 23.

  Here, as in the present embodiment, when the positive electrode 41 of the electrode body 40 is covered with the separator 44 while the negative electrode 46 is exposed, the sealing can functions as the positive electrode can 20. When the gasket upper part 31 a provided on the inner surface of the positive electrode can 20 is peeled off, there is a high possibility that a short circuit will occur between the positive electrode can 20 and the negative electrode 46.

  On the other hand, as described above, the gasket 30 is configured such that the gasket upper portion 31a is not easily peeled off from the inner surface of the positive electrode can 20, thereby causing a short circuit between the positive electrode can 20 and the electrode body 40. It can be prevented from occurring.

  In addition, by making the gasket upper portion 31a difficult to peel from the inner surface of the positive electrode can 20 as described above, it is possible to prevent the electrode body 40 from being damaged by the peeled gasket upper portion 31a.

(Other embodiments)
While 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 flat part side of the positive electrode can 20 in the gasket upper part 31a is formed so that it may reach from the R part 23 to the flat part of the flat part 21. However, the flat portion side of the positive electrode can 20 in the gasket upper portion 31 a may be formed to a thickness that covers the R portion 23.

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

  In the above embodiment, the negative electrode can 10 and the positive electrode can 20 are each formed in a bottomed cylindrical shape, and the flat battery 1 is formed in a coin shape. However, the present invention is not limited thereto, and the flat battery is formed in a polygonal column shape, etc. 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 molded into a sealed can.

1 Flat battery 10 Negative electrode can (exterior can)
11 bottom 12 peripheral wall (side wall)
20 Positive electrode can (sealed can)
21 plane part 22 peripheral wall part (cylinder part)
22a Base end portion 22b Expanded diameter portion 22c Step portion 23 R portion 30 Gasket 31 Gasket inner portion 31a Gasket upper portion 31b Gasket lower portion 31c Inner surface step portion (step portion)
32 Gasket outer portion 33 Gasket tip portion 40 Electrode body 41 Positive electrode 46 Negative electrode

Claims (5)

A bottomed cylindrical outer can,
A cylindrical portion having a smaller outer shape than a side wall of the outer can and a flat portion that closes one opening of the cylindrical portion, and the outer can with respect to the outer can so as to form a space between the outer can and the outer can Sealing cans arranged in an inverted dish shape;
At least inside the sealing can, a gasket that is molded from the opening end of the cylindrical portion to the flat portion, and
The tube portion of the sealing can is provided with a step portion that expands the opening end side of the tube portion in a step shape,
The outer can has an open end on its side wall fitted into a step portion of the sealing can,
The gasket is a flat battery in which the gasket inside the sealing can at the opening end side of the cylindrical portion of the sealing can has a smaller thickness than the gasket inside the sealing can at the stepped portion of the sealing can. The flat battery according to claim 1,
The gasket has a thickness of the gasket on the inner side of the sealing can on the opening end side of the cylindrical portion between the stepped portion on the inner side of the sealing can and the opening end of the cylindrical portion. A flat battery having a stepped portion that is smaller than the thickness of the gasket on the inner side of the sealing can. The flat battery according to claim 1 or 2,
The gasket is a flat battery in which a surface on the inner side of the sealing can is formed in a taper shape so as to approach the cylindrical portion toward the opening end of the cylindrical portion. The flat battery according to any one of claims 1 to 3,
In the sealing can, an R portion for connecting the flat surface portion and the cylindrical portion with a curved surface is formed on the outer peripheral edge portion of the flat surface portion,
The gasket is a flat battery having a thickness such that a portion of the sealing can on the flat portion side reaches the flat portion of the sealing can from the R portion. The flat battery according to any one of claims 1 to 4,
In a space formed between the outer can and the sealing can, a flat battery in which an electrode body formed by alternately laminating positive and negative electrodes formed in a plate shape in the thickness direction is disposed. .

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