Gasket for cylindrical battery, manufacturing method for cylindrical battery using same, and cylindrical battery

Abstract

A gasket (28) is equipped with a cylindrically shaped cylindrical part (29), and a ring part (30) which extends in a radially inward direction from one end section of the cylindrical part (29) in the axial direction thereof. The cylindrical part (29) has a projecting part (31) which projects in a radially inward direction between both end sections thereof in the axial direction. The projecting part (31) has a first angled section positioned on the ring part 30 side thereof, and a second angled section positioned on the side thereof opposite the ring part (30), and if a sealing body (17) is placed on the ring part (30), the first angled section is formed so as not to extend beyond the top surface (39) of the flange section of the sealing body (17).

Description

[Technical Field]

[0001] The present disclosure relates to a gasket for a cylindrical battery, a method for manufacturing a cylindrical battery using the same, and a cylindrical battery. [Background technology]

[0002] A cylindrical battery includes a cylindrical outer can with a bottom, a sealing body that closes the opening of the outer can, and a gasket interposed between the outer can and the sealing body. The outer can has a crimped portion formed by bending the edge of the opening inward and fixing the sealing body to the outer can via the gasket. In the manufacturing process of a cylindrical battery, the sealing body may be used while attached to the gasket. To prevent the sealing body from slipping out of the gasket before the crimped portion is formed, a protrusion is generally provided on the inside of the gasket to cover the flange of the sealing body. For example, Patent Document 1 discloses a gasket with a protrusion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-260409 Summary of the Invention [Problem to be solved by the invention]

[0004] With conventional gaskets with protrusions, when forming the crimped portion, the edge of the outer can presses the gasket inward, causing the gasket's protrusions to easily ride up onto the flange of the seal. When the protrusions ride up onto the flange and are pushed radially inward, the gasket is pulled by the protrusions, causing the rest of the gasket to move radially inward. This can reduce the thickness of the gasket's contact with the seal, potentially creating a gap between the gasket and the outer can. If a gap forms between the gasket and the outer can, the electrolyte inside the battery may leak out when the gasket repeatedly expands and contracts due to changes in ambient temperature.

[0005] The object of the present disclosure is to provide a gasket for cylindrical batteries that is highly airtight and that is less likely to cause gaps between the gasket and the outer can when forming the crimped portion, a manufacturing method for a cylindrical battery using the same, and a cylindrical battery. [Means for solving the problem]

[0006] The gasket for cylindrical batteries according to the present disclosure comprises a cylindrical tubular portion and an annular portion extending radially inward from one axial end of the tubular portion, the tubular portion having a protrusion protruding radially inward between both axial ends, the protrusion having a first inclined portion located on the annular portion side and a second inclined portion located closer to the other axial end of the tubular portion than the first inclined portion, the first inclined portion being formed at a position that does not exceed the top surface of the flange portion of the sealing body when the sealing body is placed on the annular portion.

[0007] A method for manufacturing a cylindrical battery using a gasket according to the present disclosure includes the steps of attaching the gasket to the sealing body so that the sealing body is positioned on the annular portion, placing the gasket on a grooved portion formed by the side surface of a cylindrical outer can with a bottom protruding inward near the opening, and bending the edge of the opening of the outer can inward to form a crimped portion so that the gasket is compressed between the outer can and the sealing body.

[0008] A cylindrical battery having a gasket according to the present disclosure comprises a cylindrical outer can with a bottom and a sealing body placed on the annular portion of the gasket, and the sealing body is crimped to the outer can via the gasket. [Effects of the Invention]

[0009] According to the gasket of the present disclosure, gaps are less likely to occur between the gasket and the outer casing, making it possible to realize a cylindrical battery with high sealing properties. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a cylindrical battery according to an embodiment of the present disclosure. [Figure 2] 10 is a cross-sectional view showing a state in which a sealing body fitted with a gasket according to an embodiment is supported by a grooved portion of an outer can. FIG. [Figure 3] FIG. 2 is an enlarged cross-sectional view of a main part of the gasket according to the embodiment. [Figure 4] 3 is a cross-sectional view of a crimped portion of a cylindrical battery using a gasket according to an embodiment. FIG. [Figure 5] FIG. 10 is a cross-sectional view showing a state in which a sealing body fitted with a gasket according to a comparative example is supported by a grooved portion of an outer can. [Figure 6] FIG. 10 is a cross-sectional view of a crimped portion of a cylindrical battery using a gasket of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, with reference to the drawings, an embodiment of a cylindrical battery according to the present disclosure will be described in detail. The cylindrical battery according to the present disclosure may be a primary battery or a secondary battery. It may also be a battery using an aqueous electrolyte or a battery using a non-aqueous electrolyte. In the following, a cylindrical battery using a non-aqueous electrolyte (e.g., a lithium-ion battery) will be exemplified as a cylindrical battery that is an example of an embodiment, but the cylindrical battery according to the present disclosure is not limited thereto.

[0012] FIG. 1 is a cross-sectional view of a cylindrical battery 10 according to an embodiment. As shown in FIG. 1, the cylindrical battery 10 includes a wound electrode assembly 14, a non-aqueous electrolyte, and an outer can 16 that houses the electrode assembly 14 and the non-aqueous electrolyte. The electrode assembly 14 has a positive electrode 11, a negative electrode 12, and a separator 13, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are spirally wound with the separator 13 interposed therebetween. The outer can 16 is a cylindrical metal container that is open on one axial side and has a bottom, and the opening of the outer can 16 is closed by a sealing member 17. For ease of explanation, the sealing member 17 side of the battery is referred to as the top, and the bottom side of the outer can 16 is referred to as the bottom.

[0013] The positive electrode 11, negative electrode 12, and separator 13 that make up the electrode assembly 14 are all strip-shaped, long bodies that are spirally wound and alternately stacked in the radial direction of the electrode assembly 14. The negative electrode 12 is formed to be slightly larger than the positive electrode 11 in order to prevent lithium deposition. That is, the negative electrode 12 is formed to be longer than the positive electrode 11 in the longitudinal direction and width direction (short direction). The two separators 13 are formed to be at least slightly larger than the positive electrode 11 and are arranged, for example, to sandwich the positive electrode 11. The electrode assembly 14 includes a positive electrode lead 20 connected to the positive electrode 11 by welding or the like, and a negative electrode lead 21 connected to the negative electrode 12 by welding or the like.

[0014] Insulating plates 18 and 19 are disposed above and below the electrode body 14. In the example shown in Fig. 1 , the positive electrode lead 20 passes through a through-hole in the insulating plate 18 and extends toward the sealing body 17, and the negative electrode lead 21 passes outside the insulating plate 19 and extends toward the bottom side of the outer can 16. The positive electrode lead 20 is connected to the underside of an internal terminal plate 23 of the sealing body 17 by welding or the like, and a cap 27, which is the top plate of the sealing body 17 and is electrically connected to the internal terminal plate 23, serves as the positive electrode terminal. The negative electrode lead 21 is connected to the inner bottom surface of the outer can 16 by welding or the like, and the outer can 16 serves as the negative electrode terminal.

[0015] A gasket 28 is provided between the exterior can 16 and the sealing body 17 to ensure airtightness inside the battery. The exterior can 16 has a grooved portion 22 formed on its side that protrudes inward and supports the sealing body 17. The grooved portion 22 is preferably formed in an annular shape along the circumferential direction of the exterior can 16, and supports the sealing body 17 on its top surface via the gasket 28. The sealing body 17 is fixed to the top of the exterior can 16 by the grooved portion 22 and the open end of the exterior can 16 that is crimped to the sealing body 17.

[0016] The sealing body 17 has a structure in which, in order from the electrode body 14 side, an internal terminal plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a cap 27 are stacked. Each member constituting the sealing body 17 has, for example, a disk or ring shape, and each member except for the insulating member 25 is electrically connected to one another. The lower valve body 24 and the upper valve body 26 are connected at their respective centers, and the insulating member 25 is interposed between their respective peripheral edges. When the internal pressure of the battery increases due to abnormal heat generation, the lower valve body 24 deforms and breaks, pushing the upper valve body 26 toward the cap 27, thereby interrupting the current path between the lower valve body 24 and the upper valve body 26. When the internal pressure further increases, the upper valve body 26 breaks, and gas is discharged from the opening of the cap 27.

[0017] Next, the gasket 28 will be described with reference to Figures 2 to 4. Figures 2 to 4 are all cross-sectional views.

[0018] FIG. 2 shows a state in which the sealing body 17 with the gasket 28 attached thereto is supported by the grooved portion 22 of the outer can 16, prior to the formation of the crimped portion 42 (see FIG. 4 ). When attached to the sealing body 17, the gasket 28 abuts against the sealing body 17 at the annular portion 30 and the protrusions 31, which will be described later. Before placing the gasket 28 on the grooved portion 22, the gasket 28 can be attached to the sealing body 17 so that the sealing body 17 is placed on the annular portion 30. Alternatively, after placing the gasket 28 on the grooved portion 22, the sealing body 17 can be inserted into the gasket 28, thereby attaching the gasket 28 to the sealing body 17. That is, in the manufacturing method of the cylindrical battery disclosed herein, the steps of attaching the gasket 28 to the sealing body 17 and placing the gasket 28 on the grooved portion 22 can be interchanged.

[0019] 2, the gasket 28 includes a cylindrical tubular portion 29 and an annular portion 30 extending radially inward from one axial end of the tubular portion 29. The tubular portion 29 has an inner circumferential surface 34 extending axially on the inner circumferential side, and an outer circumferential surface 35 extending axially on the outer circumferential side. Furthermore, the tubular portion 29 includes a protrusion 31 protruding radially inward between both axial ends.

[0020] 2 , the outer diameter of cylindrical portion 29 is smaller than the inner diameter of outer can 16 and the inner diameter is larger than the outer diameter of sealing body 17. However, the size of cylindrical portion 29 is not limited to this. The inner diameter of cylindrical portion 29 may be formed to be the same as or slightly smaller than the outer diameter of sealing body 17. In this case, gasket 28 is attached to sealing body 17 by expanding cylindrical portion 29. With gasket 28 attached to sealing body 17, the outer diameter of cylindrical portion 29 may be formed to be approximately the same as the inner diameter of the opening of outer can 16, so that it can be inserted into groove portion 22 from the opening of outer can 16.

[0021] The annular portion 30 extends radially inward of the outer can 16 and is supported by the grooved portion 22. The tip of the annular portion 30 extends radially inward beyond the grooved portion 22.

[0022] The protrusion 31 has a first inclined portion 32 located on the lower side (toward the annular portion 30) and a second inclined portion 33 located on the upper side (opposite the annular portion 30) on the inner circumferential surface 34. Furthermore, the protrusion 31 may have a flat portion 36 along the axial direction of the tubular portion 29 between the first inclined portion 32 and the second inclined portion 33.

[0023] Sealing body 17 has a flange portion with a top surface 39 and a side surface 41, and a rounded corner 40 is interposed between top surface 39 and side surface 41 of the flange portion. The shape shown in the drawings is merely an example. Corner 40 may also be linear. Gasket 28 is attached so that annular portion 30 abuts against the bottom of sealing body 17 and protrusion 31 abuts against corner 40.

[0024] First inclined portion 32 is formed so as to be located below top surface 39 of the flange portion of sealing body 17 when gasket 28 is attached to sealing body 17 so that sealing body 17 is disposed on annular portion 30. By positioning first inclined portion 32 below top surface 39 of the flange portion of sealing body 17, when crimped portion 42 is formed, protrusion 31 is less likely to ride up onto top surface 39 of the flange portion of sealing body 17, and a gap is less likely to form between gasket 28 and sealing body 17.

[0025] In a cross-sectional view, the length between the first inclined portion 32 and the annular portion 30 on the inner circumferential surface 34 of the gasket 28 is shorter than the length of the side surface 41 of the sealing body 17 (the length between the bottom surface of the sealing body 17 and the corner portion 40). Furthermore, the first inclined portion 32 is formed to be located below the top surface 39 of the flange portion of the sealing body 17. As a result, when the gasket 28 is attached to the sealing body 17, the first inclined portion 32 abuts against the corner portion 40 without exceeding the top surface 39 of the flange portion. This prevents the sealing body 17 from coming off the gasket 28 before the crimped portion 42 is formed.

[0026] 3, the flat portion 36 exists between the first inclined portion 32 and the second inclined portion 33 and has a length L along the axial direction of the tubular portion 29. The provision of the flat portion 36 also has the effect of making it difficult for the portion of the gasket 28 that abuts against the corner portion 40 to flow toward the top surface 39 of the flange portion of the sealing body 17 when forming the crimped portion 42. However, the flat portion 36 is not essential in the present disclosure.

[0027] In addition to the above, by increasing the angle θ1 formed by first inclined portion 32 and a portion of inner circumferential surface 34 of tubular portion 29 adjacent to first inclined portion 32 (hereinafter referred to as angle θ1 of first inclined portion 32), it is possible to reduce the amount of gap between gasket 28 and outer can 16 when forming crimped portion 42. The reason for this is that first inclined portion 32 abuts against corner 40 of sealing body 17 to form crimped portion 42, which has the effect of preventing the portion of gasket 28 abutting corner 40 from climbing up onto top surface 39 of the flange portion of sealing body 17.

[0028] Considering the above effects, the angle θ1 of the first inclined portion 32 is preferably 130° or greater. The upper limit of the angle θ1 of the first inclined portion 32 is set from the perspective of preventing the sealing body 17 from coming off. If the angle θ1 of the first inclined portion 32 is 175° or less, when the gasket 28 is attached to the sealing body 17, the first inclined portion 32 abuts against the corner 40 of the sealing body 17, preventing the gasket 28 from coming off. Therefore, by forming the angle θ1 of the first inclined portion in the range of 130° to 175°, the gap at the crimped portion 42 can be reduced compared to conventional gaskets. Furthermore, it is more preferable to form the angle θ1 of the first inclined portion 32 in the range of 150° to 170°. This effectively prevents the sealing body 17 from coming off the gasket 28 while minimizing the gap between the gasket 28 and the outer can 16 when the crimped portion 42 is formed.

[0029] The second inclined portion 33 is formed above the first inclined portion 32 (or further above the flat portion 36, if provided). The angle θ2 formed by the second inclined portion 33 and a portion of the inner circumferential surface 34 of the cylindrical portion 29 adjacent to the second inclined portion 33 is, for example, 150°.

[0030] The first inclined portion 32 and the second inclined portion 33 do not need to be formed with flat surfaces, and may be formed with curved surfaces. In this case, the angle θ1 of the first inclined portion 32 in a cross-sectional view is defined as the angle formed by the inner circumferential surface 34 and a line connecting the root end of the first inclined portion 32 to the other end of the first inclined portion 32 on the inner diameter side, and the inner circumferential surface 34, and is an angle greater than 90°. The angle θ2 of the second inclined portion 33 is defined similarly.

[0031] Next, the mechanism by which the gasket 28 of this embodiment makes it difficult for gaps to occur between the gasket 28 and the outer can 16 when the crimped portion 42 is formed will be described with reference to FIGS.

[0032] As shown in FIG. 2 , in the gasket 28 of this embodiment, before the crimped portion 42 is formed, the first inclined portion 32 is located below the top surface 39 of the flange portion of the sealing body 17. This makes it difficult for the protrusion 31 to climb onto the top surface 39 of the flange portion of the sealing body 17 when the crimped portion 42 is formed, and makes it difficult for the protrusion 31 to be pushed radially inward of the sealing body 17. Furthermore, if the flat portion 36 is formed, the first inclined portion 32 and the flat portion 36 abut against the corner portion 40 of the sealing body 17 when the crimped portion 42 is formed. This makes it difficult for the protrusion 31 to be pushed further radially inward of the sealing body 17. As a result, the protrusion 31 of the gasket 28 1 The amount of radially inward flow of sealing body 17 is reduced in the other areas. Therefore, gasket 28 of this embodiment has the advantage that gaps are less likely to occur between gasket 28 and outer can 16 when crimping portion 42 is formed, as shown in FIG.

[0033] Furthermore, in the gasket 28 of this embodiment, the portion that abuts against the corner 40 is unlikely to move radially inward of the sealing body 17, so the protrusion 31 abuts against the corner 40 of the sealing body 17 and is pushed up from the corner 40 toward the outer can 16 by an amount equal to the thickness of the protrusion 31. This has the effect of further suppressing the occurrence of gaps.

[0034] As described above, by using the gasket 28 of this embodiment, gaps are less likely to occur between the outer can 16 and the gasket 28, and a cylindrical battery 10 with high airtightness can be realized.

[0035] The method for manufacturing a cylindrical battery 10 using the gasket 28 of this embodiment described above is as follows. First, the gasket 28 is attached to the sealing body 17 so that the sealing body 17 is positioned on the annular portion 30. At this time, the first inclined portion 32 is positioned so that it does not exceed the top surface 39 of the flange portion of the sealing body 17. Second, the sealing body 17 with the gasket 28 attached is placed on a grooved portion 22 formed by inwardly protruding the side surface near the opening of a cylindrical outer can 16 with a bottom. Third, the edge of the opening of the outer can 16 is bent inward to form a crimped portion 42 so that the gasket 28 is compressed between the outer can 16 and the sealing body 17. In this manner, the cylindrical battery 10 is manufactured.

[0036] According to the method for manufacturing a cylindrical battery using the gasket of this embodiment, gaps are less likely to occur between the outer casing and the gasket at the crimped portion, making it possible to manufacture a cylindrical battery with high sealing properties.

[0037] The present disclosure will be explained in more detail below with reference to examples, but is not limited to these examples.

[0038] [Preparation of positive electrode plate] LiNi as the positive electrode active material 0.8 Co 0.15 Al 0.05 O2 was used. 100 parts by weight of the positive electrode active material, 1.7 parts by weight of polyvinylidene fluoride as a binder, and 2.5 parts by weight of acetylene black as a conductive agent were mixed in a dispersion medium to prepare a positive electrode mixture slurry. The positive electrode mixture slurry was applied to both sides of an aluminum foil positive electrode current collector, excluding the connection portion of the positive electrode tab, and dried. The coating was then compressed to a predetermined thickness to obtain a positive electrode plate. This positive electrode plate was cut to the predetermined dimensions, and an aluminum positive electrode tab was attached to the exposed portion of the current collector by ultrasonic welding.

[0039] [Preparation of negative electrode plate] Graphite was used as the negative electrode active material. 100 parts by mass of the negative electrode active material, 0.6 parts by mass of polyvinylidene fluoride as a binder, and carboxymethyl cellulose as a thickener were used. Su and The mixture was mixed with an appropriate amount of water in a twin-arm mixer to prepare a negative electrode mixture slurry. This negative electrode mixture slurry was applied to both sides of a copper foil negative electrode current collector, excluding the connection portion of the negative electrode tab, and then dried. The coating was then compressed to a predetermined thickness to obtain a negative electrode plate. This negative electrode plate was cut to a predetermined size, and a negative electrode tab made of a Ni-Cu-Ni clad material was attached to the exposed portion of the current collector by ultrasonic welding.

[0040] [Preparation of non-aqueous electrolyte] A non-aqueous electrolyte solution was prepared by dissolving lithium hexafluorophosphate (LiPF6) as an electrolyte in a mixed solvent of ethylene carbonate (EC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC) to a concentration of 1.0 mol / L.

[0041] [Preparation of gaskets in the examples] To understand the effect on the gap between the outer can and the gasket, gaskets with different protrusion parameters were prepared. The parameters are shown in Figure 3. Examples 1 to 4 were prepared in which the angle θ1 of the first inclined portion and the length L of the straight line of the flat portion were changed. The angle θ2 of the second inclined portion was uniformly set to 150°. The parameter values ​​for Examples 1 to 4 are shown below. Example 1: θ1 = 150°, θ2 = 150°, L = 0.05 mm Example 2: θ1 = 150°, θ2 = 150°, L = 0.1 mm Example 3: θ1 = 170°, θ2 = 150°, L = 0.05 mm Example 4: θ1 = 170°, θ2 = 150°, L = 0.1 mm

[0042] [Preparation of gasket for comparative example] As a comparative example, gasket 43 shown in FIG. 5 was prepared. Unlike the gasket of the example, gasket 43 of the comparative example was formed such that, when sealing body 17 was placed on annular portion 30 of gasket 43, a portion of the lower inclined portion of protrusion 37 exceeded top surface 39 of the flange portion of sealing body 17. In addition, upper and lower inclined portions of protrusion 37 were directly connected to form vertex 38. Following the example, the parameter values ​​are shown below when the angle between the lower inclined portion and the inner peripheral surface is θ1 and the angle between the upper inclined portion and the inner peripheral surface is θ2. Comparative example: θ1=120°, θ2=150°

[0043] [Cylindrical battery fabrication] The positive and negative electrode plates were spirally wound with a polyolefin-based resin microporous film interposed between them to produce an electrode assembly. This electrode assembly was inserted into an outer can made by drawing a steel sheet, with a disc-shaped can bottom insulating plate interposed between them, and the negative electrode tab connected to the negative electrode plate was connected to the bottom of the outer can by welding. Next, an insulating plate was placed on top of the electrode assembly, and a U-shaped groove was formed in the circumferential direction on the side of the outer can above the insulating plate by plastic working. A predetermined amount of the prepared nonaqueous electrolyte was then poured into the outer can containing the electrode assembly. The positive electrode tab connected to the positive electrode plate was then connected to the sealing member by welding. While folding the positive electrode tab, a sealing member with a gasket attached was placed on the groove of the outer can. The edge of the opening of the outer can was bent inward to form a crimped portion so that the gasket was compressed between the outer can and the sealing member, thereby producing a cylindrical battery.

[0044] [Gap measurement and evaluation results] Six cylindrical batteries were fabricated for each of Examples 1 to 4 and the Comparative Example, and the gap size at the crimped portion was measured by observing the cross section of the sealing body. The gap at the crimped portion in the Comparative Example was observed at the position shown in Figure 6, and the maximum gap size was measured. The maximum gap size was also measured for each of Examples 1 to 4 in the same manner as for the Comparative Example. The average value of the gap size at the crimped portion of the fabricated cylindrical batteries for each of Examples 1 to 4 and the Comparative Example is shown in Table 1.

[0045] [Table 1]

[0046] The gaps at the crimped portions of Examples 1 to 4 are clearly smaller than those of the comparative example. Therefore, it can be seen that the gaskets of the examples are more effective at reducing the gaps at the crimped portions than the comparative example. It can also be seen that the gaps of the gaskets of the examples are reduced by increasing the angle θ1 of the first inclined portion. It can also be seen that the gaps are reduced by increasing the straight line length L of the flat portion.

[0047] The smaller the gap, the better the sealing performance. Therefore, by increasing the angle θ1 of the first inclined portion, the gap size becomes smaller and the sealing performance improves. The evaluation results show that by making the angle θ1 of the first inclined portion larger than that of the comparative example, the gap size of the crimped portion can be made smaller than that of the conventional gasket. For example, by forming the angle θ1 of the first inclined portion in the range of 130° to 175°, the gap size of the crimped portion can be made smaller and the sealing performance can be improved. Furthermore, it is preferable to set the angle θ1 of the first inclined portion to 150° to 170°.

[0048] In comparison with the comparative example, it can be seen that providing a flat portion reduces the gap size and improves the airtightness. Also, by increasing the straight line length L of the flat portion, the gap size is reduced and the airtightness is improved.

[0049] It should be noted that the present invention is not limited to the above-described embodiment and its modifications, and various changes and modifications are possible within the scope of the claims of this application. [Explanation of symbols]

[0050] 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16 Outer can, 17 Sealing body, 18, 19 Insulating plate, 20 Positive electrode lead, 21 Negative electrode lead, 22 Grooved portion, 23 Internal terminal plate, 24 Lower valve body, 25 Insulating member, 26 Upper valve body, 27 Cap, 28, 43 Gasket, 29 Cylindrical portion, 30 Ring portion, 31 Protrusion portion, 32 First inclined portion, 33 Second inclined portion, 34 Inner peripheral surface, 35 Outer peripheral surface, 36 Flat portion, 37 Protrusion portion, 38 Vertex, 39 Top surface, 40 Corner portion, 41 Side, 42 Crimped portion, θ1 Angle of first inclined portion, θ2 Angle of second inclined portion

Claims

1. A gasket for a cylindrical battery that is compressed and fixed between a bottomed cylindrical outer can and a sealing body, A cylindrical tubular portion; a circular ring portion extending radially inward from one axial end of the cylindrical portion; Equipped with the cylindrical portion has a protrusion protruding radially inward between both axial ends, the protrusion has a first inclined portion located on the annular portion side and a second inclined portion located on the other end side of the cylindrical portion in the axial direction than the first inclined portion, the first inclined portion is formed at a position that does not exceed a top surface of a flange portion of the sealing body when the sealing body is placed on the annular portion. Gasket for cylindrical batteries.

2. the first inclined portion is formed at a position where it abuts against a corner portion interposed between a top surface and a side surface of the flange portion when the sealing body is placed on the annular portion. The gasket for a cylindrical battery according to claim 1 .

3. the protrusion has a flat portion along the axial direction of the cylindrical portion between the first inclined portion and the second inclined portion, The gasket for a cylindrical battery according to claim 1 or 2.

4. an angle formed by the first inclined portion and a portion of the inner circumferential surface of the cylindrical portion adjacent to the first inclined portion is 130° or more and 175° or less; The gasket for a cylindrical battery according to any one of claims 1 to 3.

5. A method for manufacturing a cylindrical battery using the gasket according to any one of claims 1 to 4, attaching the gasket to the sealing body so that the sealing body is disposed on the annular portion; placing the gasket on a grooved portion of the outer can, the side surface of which near the opening is formed to bulge inward; and bending an edge of the opening of the outer can inward to form a crimped portion so as to compress the gasket between the outer can and the sealing body. Cylindrical battery manufacturing method.

6. The gasket according to any one of claims 1 to 4, a cylindrical outer can with a bottom; a sealing body disposed on the annular portion of the gasket; Equipped with the sealing body is fixed to the outer can by crimping via the gasket; Cylindrical battery.

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