Cylindrical battery

Abstract

A first curved surface (41) that is convex toward the upper side in the axial direction and the outer side in the radial direction is provided at a corner part (40) on the upper side in the axial direction and the outer side in the radial direction of a sealing body (17). When t1 is defined as the maximum thickness in the axial direction of an outer portion (45) of the sealing body (17) located radially outward of a tip (15) on the opening side on an inner surface (65) of an exterior can (16) and t2 is defined as the maximum radius of curvature of a first curved surface (41) in an axial cross section, then t2 / t1 ≥1 / 2 is established. According to a battery (10) of the present disclosure, even if the thickness of a gasket (28) is increased in order to suppress electrolyte leakage, warping of the sealing body (17) is unlikely to occur.

Description

Cylindrical battery

[0001] The present disclosure relates to cylindrical batteries.

[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 and a long negative electrode are wound with a separator interposed therebetween, a bottomed cylindrical outer can that houses the electrode body, and a sealing body caulked and fixed to the opening of the outer can via a gasket. The sealing body electrically connected to the positive electrode constitutes a positive electrode terminal, and the outer can electrically connected to the negative electrode constitutes a negative electrode terminal.

[0003] Japanese Patent Application Laid-Open No. 2006-147180

[0004] Although it will be described in detail later with reference to FIG. 5, when the sealing body is caulked and fixed to the opening of the outer can via a gasket, the sealing body is pressed from the corner of the outer can formed by bending during caulking through the gasket in the radially inner and axially bottom side directions. In such a background, in order to effectively prevent the electrolyte from flowing to the opening side by capillary action between the inner surface of the outer can and the gasket and leaking to the outside, if the gasket thickness is increased to reduce the gap between the outer can and the gasket, the force received by the sealing body from the corner of the outer can through the gasket in the radially inner and axially bottom side directions increases, and there is a risk that the central portion in the radial direction of the sealing body is warped so as to deform to the axially bottom side. Therefore, an object of the present disclosure is to provide a cylindrical battery in which warping of the sealing body is unlikely to occur even when the gasket thickness is increased to suppress electrolyte leakage.

[0005] To solve the above problems, the cylindrical battery according to this disclosure comprises an electrode body, an outer casing housing the electrode body, and a sealing body crimped and fixed to the opening of the outer casing via a gasket, wherein a first curved surface is provided at the radially outer corner of the sealing body opposite to the electrode body side in the axial direction and convex radially outward, and when the maximum axial thickness of the outer portion of the sealing body located radially outward from the tip of the opening side on the inner surface of the outer casing is t1, and the maximum radius of curvature of the first curved surface in the axial cross-section is t2, then t2 / t1 ≥ 1 / 2 holds. Note that the units of each physical quantity used in this specification are values ​​in the same unit system, for example, in the MKS unit system, t2 and t1 are values ​​based on meters.

[0006] According to the cylindrical battery described herein, even if the gasket thickness is increased to suppress electrolyte leakage, warping of the sealing body is less likely to occur.

[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. 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 in the cylindrical battery of the reference example. This is an enlarged cross-sectional view of the area around the shoulder portion illustrating the problem of the cylindrical battery of the reference 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. Furthermore, the cylindrical battery of this disclosure may 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 direction) sealing body 17 side of the cylindrical battery 10 is referred to as "upper," and the axial bottom 68 side of the outer casing 16 is referred to as "lower." The numerous components described below include several optional components that are not essential. Furthermore, this disclosure is not limited to the embodiments and modifications described below, and various improvements and modifications are possible within the scope of the claims of this application and their equivalents.

[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 sealed using 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. ６ Lithium 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) joined at their radial centers, an annular insulating plate sandwiched between the two rupture plates, and a convex terminal cap covering 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 that order from the electrode 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 end of the negative electrode current collector, on the winding end side in the winding direction. However, the battery may have multiple positive electrode leads, each with one end joined to multiple locations on the positive electrode current collector spaced apart in the longitudinal direction of the positive electrode, and the other end of each positive electrode lead may be joined to a current collector plate included in the sealing body by welding or the like. Alternatively, the upper end of the electrode body may be formed by a strip-shaped positive electrode current collector exposed portion (a portion in which the positive electrode current collector is exposed without a positive electrode mixture layer), and this positive electrode current collector exposed portion may be joined to the current collector plate included in the sealing body by welding or the like.

[0024] The negative electrode lead may be electrically connected to the winding start end in the winding direction of the negative electrode current collector. Alternatively, the electrode body may have two negative electrode leads, with one end of one negative electrode lead electrically connected to the winding start end in the winding direction of the negative electrode current collector and the other end of the negative electrode lead electrically connected to the outer casing. Furthermore, one end of the other negative electrode lead may be electrically connected to the winding end in the winding direction of the negative electrode current collector and the other end of the negative electrode lead electrically connected to the outer casing.

[0025] Alternatively, one end of a negative electrode lead may be electrically connected to the winding start end of the negative electrode current collector in the winding direction, and the other end of the negative electrode lead may be electrically connected to the outer casing. In addition, or independently, the negative electrode and the outer casing may be electrically connected by bringing the winding end of the negative electrode current collector in the winding direction into contact with the inner surface of the outer casing. Alternatively, the lower end of the electrode body may be composed of a wound strip-shaped negative electrode current collector exposed portion (a portion in which the negative electrode current collector is exposed without a negative electrode mixture layer), and this negative electrode current collector exposed portion may be joined to the upper surface of the current collector plate by welding or the like, while the lower surface of the current collector plate may be joined to the bottom of the outer casing by welding or the like. Furthermore, the negative electrode may be electrically connected to the sealing body, and the positive electrode may be electrically connected to the outer casing.

[0026] 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 extend radially outward. The axial thickness of the thin-walled portion 53 decreases as it extends radially outward.

[0027] 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).

[0028] 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.

[0029] 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.

[0030] 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 from the radially outer to the inward direction, starting from the annular outer edge 54, to a downward slope, and the outer edge 54 ruptures, releasing the gas. The outer edge 54 constitutes the rupture portion of the sealing body (sealing plate) 17 that ruptures as the internal pressure rises. 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.

[0031] Figure 3 is an enlarged cross-sectional view of the shoulder area in Figure 1. As shown in Figure 3, a first curved surface 41 is provided on the axially upper (opposite side from the axial electrode body 14 side) and radially outer corner 40 of the sealing body 17, which is convex axially upper and radially outward. When the maximum axial thickness of the outer portion 45 of the sealing body 17 located radially outward from the tip 15 on the opening side of the inner surface 65 of the outer can 16 is t1, and the maximum radius of curvature of the first curved surface 41 in the axial cross-section is t2, then t2 / t1 ≥ 1 / 2 holds. The first curved surface 41 can be manufactured, for example, by forging, by pressing the curved surface of a mold having a corresponding curved surface against the corner 40 of the sealing body 17. Alternatively, the sealing body 17 having the first curved surface 41 can also be manufactured by die casting. In this embodiment, when the sealing body 17 is composed of a single sealing plate (rupture plate), it is more preferable to create the first curved surface 41 by plastic deformation using a mold, considering manufacturing efficiency.

[0032] Next, the effects of the battery 10 of this disclosure will be explained. Figure 4 is an enlarged cross-sectional view corresponding to Figure 3 of the cylindrical battery 110 of the reference example. As shown in Figure 4, even in the cylindrical battery (hereinafter simply referred to as battery) 110, there is a curved surface 141 that is convex in the axial direction upward and radially outward at the axially upward and radially outward corner 140 of the sealing body (rupture plate) 117. However, in the battery 110, only a small area of ​​the curved surface 141 exists at the corner 140, and when the maximum axial thickness of the outer portion 145 of the sealing body 117 located radially outward from the tip 15 on the opening side of the inner surface 65 of the outer casing 16 is t5, and the maximum radius of curvature of the curved surface 141 in the axial cross-section of the sealing body 117 is t6, then t6 / t5 < 1 / 2 holds true around the entire radial circumference of the sealing body 117.

[0033] In such a battery 110, the following problems may occur. Specifically, when the upper end of the outer casing 16 is bent inward toward the peripheral edge 151 to form the shoulder portion 38 by crimping, as shown in Figure 5, the lower side of the gasket 128 receives an upward axial force indicated by arrow A from the upper surface 34a of the grooved portion 34, and the upper side of the gasket 128 receives an downward axial force indicated by arrow B from the crimping mold 80 via the shoulder portion 38. As a result, the gasket 128 is strongly compressed in the axial direction by the upper surface 34a and the shoulder portion 38, and the tip of the upper side of the gasket 128 rises toward the radial opening.

[0034] However, in the gasket 128, the corner-facing portion 128a that faces the radially outer corner 60 of the shoulder portion 38 has little room for relief, so the density of the corner-facing portion 128a increases, and stress in the radially inward and axially downward direction, as indicated by arrow C, is concentrated on the corner-facing portion 128a. In this context, if the thickness of the gasket 128 is increased to reduce the gap between the outer can 16 and the gasket 128 in order to effectively prevent the non-aqueous electrolyte from flowing to the opening side by capillary action between the inner surface 65 of the outer can 16 and the gasket 128 and leaking to the outside, the axially upper and radially outer corner 140 of the sealing body 117 may receive a large force from the gasket 128 in the direction indicated by arrow C, causing the sealing body 117 to warp so that the radially central part deforms toward the axial bottom 68 (see Figure 1), and the sealing body 117 may deform from a state bordered by a solid line to a state bordered by a dotted line.

[0035] In contrast, with the battery 10 of this disclosure, the above-mentioned t2 / t1 ≥ 1 / 2 holds true, and a first curved surface 41 with a large area exists at the axially upper and radially outer corner 40 of the sealing body 17. Therefore, the relief area of ​​the corner-facing portion 28a of the gasket 28 that faces the radially outer corner 60 of the shoulder portion 38 is increased, and the stress acting on the corner-facing portion 28a can be relaxed.

[0036] Therefore, in order to effectively prevent the non-aqueous electrolyte from flowing towards the opening side by capillary action between the inner surface 65 of the outer can 16 and the gasket 28 and leaking to the outside, even if the thickness of the gasket 28 is increased to reduce the gap between the outer can 16 and the gasket 28, the axially upper and radially outer corner 40 of the sealing body 17 is less likely to be subjected to a large force from the corner opposing portion 28a. As a result, it is possible to simultaneously achieve both effective suppression of leakage of the non-aqueous electrolyte to the outside and effective suppression of warping of the sealing body 17, which are in a trade-off relationship.

[0037] Since leakage of the non-aqueous electrolyte to the outside can be effectively suppressed, it is preferable that t2 / t1 ≤ 2 / 3 holds true. Furthermore, in the case where the sealing body 17 is composed of a single sealing plate (rupture plate), as in the battery 10 of this embodiment, the strength (rigidity) of the sealing body 17 decreases, making it more prone to warping. Therefore, the suppression of warping of the sealing body 17, which is an effect of the technology of this disclosure, becomes particularly pronounced.

[0038] As shown in Figure 3, a second curved surface 61 is provided on the inner surface 65 of the corner portion 60 (the radially outer corner portion of the shoulder) of the outer can 16, which is located furthest axially upward and radially outward. The variation in the maximum radius of curvature t3 of the second curved surface 61 around the entire circumference of the outer can 16 depends on the crimping involving multiple members, making it difficult to control with high precision.

[0039] On the other hand, the variation in the maximum radius of curvature t2 of the first curved surface 41 around the entire circumference of the sealing body 17 can be adjusted during the manufacturing of the sealing body 17 as a single unit, making it easy to control with high precision. This makes it easier to define the space defined by the outer can 16 and the sealing body 17 with high precision, and makes it easier to achieve both effective suppression of warping of the sealing body 17 and effective suppression of leakage of non-aqueous electrolytes. Therefore, when the variation is taken as the sum of the differences from the average value, it is preferable that the variation in the maximum radius of curvature t2 of the first curved surface 41 around the entire circumference of the sealing body 17 is smaller than the variation in the maximum radius of curvature t3 of the second curved surface 61 around the entire circumference of the outer can 16.

[0040] Since it is easier to effectively suppress the warping of the sealing body 17, it is preferable that t4 / t1 ≥ 1 / 2 holds when the maximum axial thickness of the outer portion 45 of the sealing body 17 located radially outward from the tip 15 on the opening side of the inner surface 65 of the outer can 16 is t1, and the length of the first curved surface 41 in the axial cross-section is t4. Furthermore, since it is easier to effectively suppress the leakage of non-aqueous electrolytes, it is preferable that t4 / t1 ≥ 2 / 3 holds.

[0041] 10 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, 28 Gasket, 28a Opposing corner portion, 30 Bottom surface of sealing body, 34 Grooved portion, 34a Top surface of grooved portion, 38 Shoulder portion, 40 Corner portion on the axial upper and radially outer side of sealing body, 41 First curved surface, 45 Outer portion, 50 Cylindrical portion, 51 Peripheral portion, 52 Terminal portion, 53 Thin-walled portion, 54 Annular outer edge of thin-walled portion, 60 Corner portion on the radially outer side of the shoulder portion, 61 Second curved surface, 65 Inner surface of outer can, 68 Bottom of outer can, 80 Mold.

Claims

1. A cylindrical battery comprising: an electrode body; an outer can for housing the electrode body; and a sealing body crimped and fixed to the opening of the outer can via a gasket, wherein a first curved surface is provided at the radially outer corner of the sealing body opposite to the electrode body side in the axial direction and convex radially outward, and when the maximum axial thickness of the outer portion of the sealing body located radially outward from the tip of the opening side on the inner surface of the outer can is t1, and the maximum radius of curvature of the first curved surface in the axial cross-section is t2, the condition t2 / t1 ≥ 1 / 2 holds.

2. The cylindrical battery according to claim 1, wherein the sealing body is composed of a single sealing plate having a rupture portion that ruptures as the internal pressure increases.

3. The cylindrical battery according to claim 1 or 2, wherein a second concave curved surface is provided on the inner surface of the corner of the outer casing that is furthest from the electrode body side in the axial direction and radially outward, and when the variation is taken as the sum of the differences from the average value, the variation in the maximum radius of curvature of the first curved surface over the entire circumference of the sealing body is smaller than the variation in the maximum radius of curvature of the second curved surface over the entire circumference of the outer casing.

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