Cylindrical battery

Abstract

A battery (10) is provided with an electrode body in which a long positive electrode and a long negative electrode are wound while a separator is interposed therebetween, a outer can (16) housing the electrode body and having, at one end in the axial direction, an annular shoulder part (38) extending radially inward, and a sealing body (17) for closing an opening of the outer can (16) while a gasket (28) is interposed therebetween. A distal end surface (60) of the shoulder part (38) on one side in the axial direction is positioned substantially parallel to the radial direction. A peripheral part (51) of the sealing body (17) has an annular protruding part (61) protruding toward the shoulder part (38). With the battery (10) according to the present disclosure, it is possible to easily connect the shoulder part (38) of the outer can (16) to a current collection member. It is also possible to inhibit exudation of an electrolyte.

Description

Cylindrical battery

[0001] The present disclosure relates to a cylindrical battery.

[0002] Conventionally, as a cylindrical battery, there is one described in Patent Document 1. This cylindrical battery includes an electrode body in which a long positive electrode including a positive electrode current collector and a positive electrode mixture layer and a long negative electrode including a negative electrode current collector and a negative electrode mixture layer are wound via a separator, an electrolyte, a bottomed cylindrical outer can that houses the electrode body and the electrolyte, and a sealing body that is caulked and fixed to the opening of the outer can via a gasket. The sealing body electrically connected to the positive electrode current collector via a positive electrode lead constitutes a positive electrode terminal, and the outer can electrically connected to the negative electrode current collector via a negative electrode lead constitutes a negative electrode terminal.

[0003] Japanese Unexamined Patent Application Publication No. 2013 - 016328

[0004] When manufacturing a battery pack by electrically connecting a plurality of cylindrical batteries with a current collecting member, there are cases where the sealing body is used as a first electrode terminal and the shoulder portion of the outer can bent on the upper surface of the sealing body via a gasket is used as a second electrode terminal. In such a case, when the upper surface of the shoulder portion is arranged substantially parallel to the radial direction of the cylindrical battery, the connection between the current collecting member and the second electrode terminal can be easily performed. However, when the upper surface of the shoulder portion is arranged substantially parallel to the radial direction of the cylindrical battery, the electrolyte is more likely to leak out compared to the case where the inner end portion on the radial direction side of the shoulder portion is inclined toward the sealing body to locally compress the gasket. Therefore, an object of the present disclosure is to provide a cylindrical battery capable of easily connecting a current collecting member and a shoulder portion as an electrode terminal and suppressing the leakage of the electrolyte.

[0005] To solve the above problems, the cylindrical battery according to the present disclosure includes an electrode body in which a long positive electrode and a long negative electrode are wound via a separator, an outer can having an annular shoulder portion extending inward in the radial direction at one axial end portion and housing the electrode body, and a sealing body that closes the opening of the outer can via a gasket. The tip surface on one axial side of the shoulder portion is arranged substantially parallel to the radial direction, and the peripheral edge portion of the sealing body has an annular protruding portion protruding toward the shoulder portion.

[0006] According to the cylindrical battery described herein, the shoulder portion serving as an electrode terminal can be easily connected to the current collector, and electrolyte leakage can also be suppressed.

[0007] This is an axial cross-sectional view of a cylindrical battery according to one embodiment of the present disclosure. This is a perspective view of the electrode body of the cylindrical battery. This is an enlarged cross-sectional view of the area around the shoulder portion in Figure 1. This is an enlarged cross-sectional view corresponding to Figure 3 of the cylindrical battery of the reference example. This is an enlarged cross-sectional view corresponding to Figure 3 of the cylindrical battery of the first modified example. This is an enlarged cross-sectional view corresponding to Figure 3 of the cylindrical battery of the second modified example.

[0008] Hereinafter, embodiments of the cylindrical battery according to this disclosure will be described in detail with reference to the drawings. The cylindrical battery of this 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 non-aqueous electrolyte secondary battery (lithium-ion battery) using a non-aqueous electrolyte will be given as an example of a cylindrical battery 10, which is one embodiment, but the cylindrical battery of this disclosure is not limited to this.

[0009] It is intended from the outset that new embodiments can be constructed by appropriately combining the characteristic features of the embodiments and modifications described below. In the following embodiments, the same reference numerals are used for the same components in the drawings, and redundant explanations are omitted. Multiple drawings include schematic diagrams, and the dimensional ratios such as length, width, and height of each component do not necessarily match between different drawings. In this specification, the axial (height) side of the sealing body 17 of the cylindrical battery 10 is referred to as "upper," and the axial side of the bottom 68 of the outer casing 16 is referred to as "lower." Among the components described below, components that are not described in the independent claim indicating the highest-level concept are optional components and are not essential components.

[0010] Figure 1 is an axial cross-sectional view of a cylindrical battery 10 according to one embodiment of the present disclosure, and Figure 2 is a perspective view of the electrode body 14 of the cylindrical battery 10. As shown in Figure 1, the cylindrical battery (hereinafter simply referred to as battery) 10 comprises a wound electrode body 14, a non-aqueous electrolyte (not shown), a bottomed cylindrical metal outer casing 16 that houses the electrode body 14 and the non-aqueous electrolyte, and a sealing body 17 that closes the opening of the outer casing 16 via a gasket 28. In the example shown in Figure 1, the outer casing 16 has a bottomed cylindrical shape, but the outer casing may have a cylindrical shape, and the battery may have a structure in which the openings on both axial sides of the outer casing are each sealed by sealing bodies.

[0011] As shown in Figure 2, the electrode body 14 has a wound structure in which a long positive electrode 11 and a long negative electrode 12 are wound around two long separators 13. 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 both the longitudinal and widthwise (short-side) directions. 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 negative electrode 12 may constitute the starting end of the winding of the electrode body 14. However, generally, the separators 13 extend beyond the starting end of the winding of the negative electrode 12, and the starting end of the winding of the separators 13 becomes the starting end of the winding of the electrode body 14.

[0012] Non-aqueous electrolytes are ionic conductive (e.g., lithium ion conductive). Non-aqueous electrolytes may be liquid electrolytes (electrolytes) or solid electrolytes. Liquid electrolytes (electrolytes) contain a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of non-aqueous solvents include esters, ethers, nitriles, amides, and mixtures of two or more of these. Examples of non-aqueous solvents include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixtures thereof. Non-aqueous solvents may contain halogen-substituted compounds (e.g., fluoroethylene carbonate) in which at least some of the hydrogen atoms in these solvents are replaced with halogen atoms such as fluorine. Examples of electrolyte salts include LiPF4. ６Lithium salts such as these are used.

[0013] As solid electrolytes, for example, solid or gel-like polymer electrolytes, inorganic solid electrolytes, etc., are used. Polymer electrolytes include, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt and a matrix polymer. As matrix polymers, for example, polymer materials that absorb non-aqueous solvents and gel are used. As polymer materials, for example, fluororesins, acrylic resins, polyether resins, etc., are used. As inorganic solid electrolytes, for example, materials known for all-solid-state lithium-ion secondary batteries, etc. (for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.) are used.

[0014] The positive electrode 11 comprises a positive electrode current collector and a positive electrode mixture layer formed on both sides of the positive electrode current collector. The positive electrode current collector can be made of a metal foil that is stable within the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film with the metal arranged on its surface. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 can be manufactured, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder onto the positive electrode current collector, drying the coating, and then compressing it to form the positive electrode mixture layer on both sides of the current collector.

[0015] The positive electrode active material is mainly composed of a lithium-containing metal composite oxide. Examples of metal elements contained in the lithium-containing metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, and W. A preferred example of a lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0016] Examples of conductive agents included in the positive electrode mixture layer include carbon black such as acetylene black and Ketjen black, and carbon materials such as graphite. Examples of binders included in the positive electrode mixture layer include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, and polyolefin resins. These resins may be used in combination with cellulose derivatives such as carboxymethylcellulose (CMC) or its salts, polyethylene oxide (PEO), etc.

[0017] The negative electrode 12 comprises a negative electrode current collector and a negative electrode mixture layer formed on both sides of the negative electrode current collector. The negative electrode current collector can be made of a metal foil that is stable within the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with the metal arranged on its surface. The negative electrode mixture layer contains a negative electrode active material and a binder. The negative electrode 12 can be manufactured, for example, by applying a negative electrode mixture slurry containing the negative electrode active material and binder onto the negative electrode current collector, drying the coating, and then compressing it to form the negative electrode mixture layer on both sides of the current collector.

[0018] Generally, carbon materials that reversibly intercept and release lithium ions are used as the negative electrode active material. Preferred carbon materials are graphite such as natural graphite such as flake graphite, lump graphite, and clay graphite, and artificial graphite such as lump graphite and graphitized mesophase carbon microbeads. The negative electrode mixture layer may contain silicon (Si) material as the negative electrode active material. In addition, metals that alloy with lithium other than Si, alloys containing such metals, compounds containing such metals, etc., may be used as the negative electrode active material.

[0019] The binder included in the negative electrode mixture layer may be fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, etc., as in the case of the positive electrode 11, but preferably styrene-butadiene rubber (SBR) or a modified version thereof is used. In addition to SBR, the negative electrode mixture layer may also contain, for example, CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, etc.

[0020] A porous sheet having ion permeability and insulating properties is used for the separator 13. Specific examples of porous sheets include microporous thin films, woven fabrics, and nonwoven fabrics. The material of the separator 13 is preferably polyethylene, polyolefin resins such as polypropylene, or cellulose. The separator 13 may have either a single-layer structure or a laminated structure. A heat-resistant layer or the like may be formed on the surface of the separator 13.

[0021] As shown in Figure 1, a positive electrode lead 20 is joined to the positive electrode 11, and a negative electrode lead 21 is joined to the end of the negative electrode 12 on the winding end side in the longitudinal direction. The battery 10 has an insulating plate 18 above the electrode body 14 and an insulating plate 19 below the electrode body 14. One end of the positive electrode lead 20 is joined to the positive electrode current collector of the positive electrode 11 of the electrode body 14. The sealing body 17 is composed of only one sealing plate (rupture plate). The positive electrode lead 20 extends towards the sealing body 17 side through a through hole in the insulating plate 18, and is then connected to the lower surface 30 of the sealing body 17 by welding or the like, so that the sealing body 17 becomes the positive electrode terminal.

[0022] The sealing body may have a laminated structure including two rupture plates (lower valve body and upper valve body) and a convex terminal cap that covers the rupture plates. Alternatively, the sealing body may have a structure in which an internal terminal plate, an annular insulating plate, and a rupture plate are laminated in order from the electrode body side. Alternatively, the sealing body may not have a rupture plate, and the bottom of the case may have a thin, easily breakable portion that breaks when the battery overheats abnormally.

[0023] The negative electrode lead 21 extends from the outside of the insulating plate 19 to the bottom 68 side of the outer casing 16. The negative electrode lead 21 is connected to the inner surface of the bottom 68 of the metal outer casing 16 by welding or the like, so that the outer casing 16 becomes the negative electrode terminal. In the example shown in Figures 1 and 2, the positive electrode lead 20 is electrically connected to an intermediate part of the positive electrode current collector, such as the center in the winding direction, and the negative electrode lead 21 is electrically connected to the winding end side of the negative electrode current collector in the winding direction. However, the negative electrode lead may also be electrically connected to the winding start side end of the negative electrode current collector in the winding direction. Alternatively, the electrode body may have two negative electrode leads, with one negative electrode lead electrically connected to the winding start side end of the negative electrode current collector in the winding direction, and the other negative electrode lead electrically connected to the winding end side of the negative electrode current collector in the winding direction. Alternatively, the negative electrode and the outer casing may be electrically connected by bringing the end of the negative electrode current collector, in the winding direction, into contact with the inner surface of the outer casing.

[0024] As shown in Figure 1, the sealing body (sealing plate) 17 has an annular peripheral portion 51 formed on the radially outward side, a terminal portion 52 formed on the radially inward side, and an annular thin-walled portion 53 that connects the peripheral portion 51 and the terminal portion 52 and is thinner than the terminal portion 52. The upper and lower surfaces of the thin-walled portion 53 are inclined surfaces that slope upward in the axial direction as they move radially outward. The axial thickness of the thin-walled portion 53 decreases as it moves radially outward.

[0025] The battery 10 has a resin gasket 28 positioned between the outer casing 16 and the sealing body 17. The gasket 28 is preferably made of an insulating material with excellent compressibility and resistance, such as PP (polypropylene), PPS (polyphenylene sulfide), PFA (perfluoroalkoxyalkane), or PPT (polypropylene terephthalate).

[0026] The peripheral edge 51 of the sealing body 17 is crimped and fixed to the opening of the outer casing 16 via a gasket 28. This seals the internal space of the battery 10. The gasket 28 is sandwiched between the outer casing 16 and the peripheral edge 51, insulating the sealing body 17 from the outer casing 16. The gasket 28 serves as a sealing material to maintain airtightness inside the battery and as an insulating material to insulate the outer casing 16 from the sealing body 17.

[0027] The outer container 16 has a cylindrical portion 50 and a bottom portion 68, and the cylindrical portion 50 includes a shoulder portion 38 and a grooved portion 34. The outer container 16 houses the electrode body 14 and the non-aqueous electrolyte. The grooved portion 34 can be formed, for example, by spinning a part of the side surface of the outer container 16 radially inward to create an annular recess radially inward. The shoulder portion 38 is formed when the peripheral portion 51 is crimped and fixed to the outer container 16, by bending the upper end of the outer container 16 inward toward the peripheral portion 51.

[0028] When the battery 10 overheats and its internal pressure rises, the sealing body 17 is pressed upward by the gas pressure, causing the thin-walled portion 53 to reverse from a downward slope starting from the annular outer edge 54 to an upward slope, and the outer edge 54 ruptures, releasing the gas. This release of gas prevents the battery 10 from rupturing due to an excessive rise in internal pressure, thereby increasing the safety of the battery 10.

[0029] Figure 3 is an enlarged cross-sectional view of the area around the shoulder portion in Figure 1. As shown in Figure 3, the tip surface (top surface) 60 on one side of the shoulder portion 38 in the axial direction is arranged substantially parallel to the radial direction. The peripheral edge 51 of the sealing body 17 has an annular projection 61 that protrudes axially toward the shoulder portion 38. The projection 61 has an annular shape when viewed from above in the axial direction, and the radial length of the top (tip surface) 62 of the projection 61 is substantially constant regardless of the circumferential position. Next, the operation and effects of the battery 10 of this embodiment will be described. Figure 4 is an enlarged cross-sectional view corresponding to Figure 3 of a cylindrical battery 310, a reference example that differs from the battery 10 in that it does not have a projection 61.

[0030] Referring to Figures 3 and 4, when manufacturing a battery pack by electrically connecting multiple batteries 10, 310 with a current collector, the sealing bodies 17, 317 may be used as positive terminals, and the shoulder portion 38 of the outer casing 16 may be used as negative terminals. In such cases, as with batteries 10, 310, current collection using the shoulder portion 38 can be easily performed by arranging the tip surface 60 of the shoulder portion 38 substantially parallel to the radial direction.

[0031] However, as in the battery 310 shown in the reference example in Figure 4, if the peripheral edge 351 of the sealing body 317 has an annular flat structure, the gasket 28 becomes less compressible compared to the case where the radially inward end of the shoulder portion is inclined toward the bottom of the outer can in the axial direction. Furthermore, the electrolyte 70 remaining at the radially outward corners of the upper surface of the grooved portion 34 may seep out from between the gasket 28 and the inner surface of the outer can due to capillary action, potentially causing rust to form on the tip side of the shoulder portion 38.

[0032] In contrast, the battery 10 of this disclosure has an annular projection 61 that protrudes axially toward the shoulder portion 38 at the peripheral edge 51 of the sealing body 17. Therefore, the gasket 28 can be locally compressed over the entire circumference in the circumferential direction by the annular projection 61, thereby suppressing the leakage of the electrolyte.

[0033] Referring to Figure 3, in the battery 10 of the embodiment, when the radial length of the opposing portion 77 that faces the shoulder portion 38 in the sealing body 17 in the axial direction is L1, and the radial length of the top portion 62 of the protruding portion 61 is L2, the cylindrical batteries of Examples 1 to 5 were manufactured by changing the ratio of L2 to L1. When the maximum length of the axial distance between the portion of the opposing portion 77 other than the protruding portion 61 and the shoulder portion 38 is L3, and the axial length of the protruding portion 61 is L4, the compression ratio of the gasket 28, defined as (L4 / L3) × 100, is constant for the cylindrical batteries of Examples 1 to 5.

[0034] <Example 1> The ratio of L2 to L1 was 10%. <Example 2> The ratio of L2 to L1 was 20%. <Example 3> The ratio of L2 to L1 was 30%. <Example 4> The ratio of L2 to L1 was 40%. <Example 5> The ratio of L2 to L1 was 50%. <Comparative Example> A battery 310 of the above reference example without the protruding portion 61 was manufactured.

[0035] (Leakage Confirmation Test) Five batteries each of Examples 1-5 and the comparative example were prepared. Each battery was then dropped 1 meter into concrete 20 times each, for a total of 60 times, with the sealing body facing upwards, with the sealing body facing downwards, and with the battery's axis oriented horizontally, to check for electrolyte leakage.

[0036]

[0037] As shown in Table 1, leakage occurred in the comparative example battery that did not have a protrusion, while no leakage occurred in any of the batteries in Examples 1 to 5. Thus, it was confirmed that even if the tip surface on one side of the shoulder portion in the axial direction is arranged substantially parallel to the radial direction, the sealing performance of the gasket is improved by providing an annular protrusion that projects toward the shoulder portion on the periphery of the sealing body.

[0038] From the viewpoint of gasket sealing performance, it is preferable that 0.1 ≤ L2 / L1. From the viewpoint of gasket durability, it is preferable that L2 / L1 ≤ 0.5. The radial length of the protrusion may vary at the circumferential position. In this case, L2 in the above two equations can be defined as the average of the radial lengths in the circumferential direction of the top (tip surface) of the annular protrusion. From the viewpoint of gasket sealing performance, it is preferable that 0.1 ≤ L4 / L3. From the viewpoint of gasket durability, it is preferable that L4 / L3 ≤ 0.5.

[0039] This disclosure is not limited to the embodiments and their variations, and various improvements and modifications are possible within the scope of the claims of this application and their equivalents.

[0040] FIG. 5 is an enlarged cross-sectional view corresponding to FIG. 3 in the battery 110 of the first modified example. As shown in FIG. 5, the battery 110 has an annular protruding portion 161 that axially protrudes toward the shoulder portion 38 at the peripheral edge portion 151 of the sealing body 117. The tip surface (upper surface) 60 on one axial side of the shoulder portion 38 is arranged substantially parallel in the radial direction. As shown in FIG. 5, the protruding portion 161 has a substantially isosceles trapezoidal shape. The protruding portion 161 has an annular shape in a top view when viewed from the upper side in the axial direction, and the radial length of the top (tip surface) 162 of the protruding portion 161 is substantially constant regardless of the circumferential position.

[0041] FIG. 6 is an enlarged cross-sectional view corresponding to FIG. 3 in the battery 210 of the second modified example. As shown in FIG. 6, the battery 210 has an annular protruding portion 261 that axially protrudes toward the shoulder portion 38 at the peripheral edge portion 251 of the sealing body 217. The tip surface (upper surface) 60 on one axial side of the shoulder portion 38 is arranged substantially parallel in the radial direction. The protruding portion 261 has an annular shape in a top view when viewed from the upper side in the axial direction, and the radial length of the top (tip surface) 262 of the protruding portion 261 is substantially constant regardless of the circumferential position.

[0042] From the viewpoint of the durability of the gasket 28, as shown in FIGS. 5 and 6, the inner peripheral ends 163, 263 of the tops 162, 262 of the protruding portions 161, 261 are located radially outside the inner peripheral ends 164, 264 of the bottoms of the protruding portions 161, 261, and the outer peripheral ends 165, 265 of the tops 162, 262 of the protruding portions 161, 261 are located radially inside the outer peripheral ends 166, 266 of the bottoms of the protruding portions 161, 261.

[0043] From the viewpoint of the durability of the gasket 28, as shown in FIG. 6, the protruding portion 261 preferably has an inner peripheral side curved portion 272 that is convex toward the inner side in the radial direction and is connected to the inner peripheral end 263 of the top 262, and an outer peripheral side curved portion 273 that is convex toward the outer side in the radial direction and is connected to the outer peripheral end 165 of the top 262. In the battery 210 of the second modified example, all of the inner peripheral surface 281 of the protruding portion 261 is a curved surface, and all of the outer peripheral surface 282 of the protruding portion 261 is a curved surface. However, only the upper end portion of the outer peripheral surface of the protruding portion may be a curved surface, or only the upper end portion of the inner peripheral surface of the protruding portion may be a curved surface.

[0044] As shown in Figure 3, in the battery 10 of the above embodiment, the radial position of the outer peripheral end 65 of the bottom of the protrusion 61 substantially coincides with the radial position of the outer radial end 69 of the peripheral edge 51. However, the protrusion only needs to be provided in a position that overlaps the shoulder portion in the axial direction, and the outer peripheral end of the bottom of the protrusion may be located radially inward from the outer radial end of the peripheral edge. Furthermore, the negative electrode may be electrically connected to the sealing body, and the positive electrode may be electrically connected to the outer casing.

[0045] 10, 110, 210 Battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16 Outer can, 17, 117, 217 Sealing body, 18, 19 Insulating plate, 20 Positive electrode lead, 21 Negative electrode lead, 28 Gasket, 34 Grooved portion, 38 Shoulder portion, 50 Cylindrical portion, 51, 151, 251 Peripheral portion, 52 Terminal portion, 53 Thin-walled portion, 54 Outer edge of thin-walled portion, 60 Tip surface of shoulder portion, 61, 161, 261 Protruding portion, 62, 162, 262 Top of protruding portion, 65, 165, 265 Outer peripheral end of top of protruding portion, 68 Bottom of outer can, 69 Radial outer end of peripheral portion, 70 Electrolyte, 77 Opposing part, 163, 263 Inner circumferential end of top, 164, 264 Inner circumferential edge of bottom of protrusion, 166, 266 Outer circumferential end of bottom of protrusion, 272 Inner circumferential curved part, 273 Outer circumferential curved part, 281 Inner circumferential surface of protrusion, 282 Outer circumferential surface of protrusion.

Claims

1. A cylindrical battery comprising: an electrode body in which a long positive electrode and a long negative electrode are wound around a separator; an outer casing for housing the electrode body, having an annular shoulder portion extending radially inward from one end in the axial direction; and a sealing body that closes the opening of the outer casing via a gasket, wherein the tip surface on one end of the shoulder portion in the axial direction is arranged substantially parallel to the radial direction, and the peripheral edge of the sealing body has an annular projection that protrudes toward the shoulder portion.

2. The cylindrical battery according to claim 1, wherein the inner circumferential end of the top of the protrusion is located radially outward from the inner circumferential end of the bottom of the protrusion, and the outer circumferential end of the top of the protrusion is located radially inward from the outer circumferential end of the bottom of the protrusion.

3. The cylindrical battery according to claim 2, wherein the protrusion has an inner circumferential curved portion that is convex radially inward and connected to the inner circumferential end of the top, and an outer circumferential curved portion that is convex radially outward and connected to the outer circumferential end of the top.

4. The cylindrical battery according to any one of claims 1 to 3, wherein L1 is the radial length of the opposing portion of the sealing body that faces the shoulder portion in the axial direction, and L2 is the radial length of the top of the protruding portion, and L1 and L2 satisfy 0.1 ≤ L2 / L1 ≤ 0.5.

Images