Cylindrical battery

Abstract

This cylindrical battery (10) comprises: an electrode body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; an electrolyte solution; a bottomed cylindrical outer can (16) that accommodates the electrode body and the electrolyte solution; a sealing body (17) that closes an opening provided in the upper part of the outer can (16); and a gasket (28) interposed between the outer can (16) and the sealing body (17). The outer can (16) has: a grooved portion (35) that protrudes radially inward below the opening and supports the gasket (28); and a crimping portion (33) that bends an end portion of the opening radially inward and crimps and fixes the sealing body (17) via the gasket (28). The gasket (28) has a recessed portion (60) in a region facing the crimping portion (33).

Description

Cylindrical battery

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

[0002] Conventionally, a cylindrical battery including a wound electrode body, a bottomed cylindrical outer can that houses an electrolytic solution, a sealing body that closes the opening of the outer can, and a gasket interposed between the outer can and the sealing body is widely known. In the process of manufacturing the battery, after inserting the electrode body into the outer can, the electrolytic solution is injected. At this time, the electrolytic solution can adhere to the inner surface of the outer can. When the end of the opening is bent during battery assembly and the sealing body is caulked and fixed through the gasket, the gasket is compressed and adheres tightly to the inner surface of the outer can. Therefore, the electrolytic solution adhering between the upper and lower surfaces of the gasket and the outer can is extruded, but the electrolytic solution interposed between the inner peripheral surface of the outer can and the gasket may seep out to the outside due to temperature changes or internal pressure changes, resulting in rust on the outer can.

[0003] For example, Patent Document 1 discloses a secondary battery in which an adhesive substance is inserted between the outer can and the gasket to close the gap.

[0004] Japanese Unexamined Patent Application Publication No. 2007-184270

[0005] However, even when an adhesive substance is inserted into the gap between the outer can and the gasket, there are still slight gaps between the adhesive substance and the outer can and between the adhesive substance and the gasket, so that the electrolytic solution intervenes. Due to the cohesive force between electrolytic solution molecules and capillary action, the electrolytic solution moves in the gap, and as a result, there is a possibility of causing rust due to liquid leakage. Therefore, it is necessary to more reliably prevent the movement of the electrolytic solution between the outer can and the gasket.

[0006] The cylindrical battery according to the present disclosure includes an electrode body in which a positive electrode and a negative electrode are wound through a separator, an electrolytic solution, a bottomed cylindrical outer can that houses the electrode body and the electrolytic solution, a sealing body that closes an opening provided in the upper part of the outer can, and a gasket interposed between the outer can and the sealing body. The outer can has a grooved portion that protrudes radially inward below the opening to support the gasket, and a caulking portion that bends the end of the opening radially inward and caulks and fixes the sealing body through the gasket. The gasket is characterized in that it has a concave portion in a region facing the caulking portion.

[0007] According to the cylindrical battery described herein, the movement of electrolyte between the outer casing and the gasket is suppressed, thereby preventing leakage.

[0008] This is a cross-sectional view in the axial direction of a cylindrical battery, which is an example of an embodiment. This is a cross-sectional view of the area around the crimped portion of a cylindrical battery, which is an example of an embodiment.

[0009] 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 cylindrical battery 10 which is a non-aqueous electrolyte secondary battery (lithium-ion battery) using a non-aqueous electrolyte will be given as an example, but the cylindrical battery of this disclosure is not limited to this.

[0010] 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. In addition, 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 side of the cylindrical battery 10 with the sealing body 17 in the axial direction (height direction) is referred to as "upper," and the side of the outer casing 16 with the bottom 68 in the axial direction is referred to as "lower." Furthermore, 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.

[0011] Figure 1 is an axial cross-sectional view of a cylindrical battery 10, which is an example of an embodiment. As shown in Figure 1, the cylindrical battery 10 comprises a wound electrode body 14, a non-aqueous electrolyte (not shown), a bottomed cylindrical outer casing 16 that houses the electrode body 14 and the non-aqueous electrolyte, and a sealing body 17 that closes an opening provided at the top of the outer casing 16. The electrode body 14 has a positive electrode 11, a negative electrode 12, and a separator 13 interposed between the positive electrode 11 and the negative electrode 12. The cylindrical battery 10 further comprises a resin gasket 28 interposed between the outer casing 16 and the sealing body 17.

[0012] A non-aqueous electrolyte comprises a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous solvent may include, for example, esters, ethers, nitriles, amides, and mixtures of two or more of these. The non-aqueous solvent may also contain halogen-substituted solvents in which at least some of the hydrogen atoms of the solvent are replaced with halogen atoms such as fluorine. The electrolyte salt may include LiPF ６ Lithium salts such as these are used.

[0013] The electrode body 14 has a long positive electrode 11, a long negative electrode 12, and two long separators 13, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound around each other via the separators 13. A positive electrode lead 20 is joined to the positive electrode 11, and a negative electrode lead 21 is joined to the negative electrode 12. The negative electrode 12 is formed to be slightly larger than the positive electrode 11 in order to suppress lithium deposition, and is formed to be longer than the positive electrode 11 in both the longitudinal and width (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.

[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 positive electrode 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 negative electrode 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 CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, etc.

[0020] The separator 13 is made of a porous sheet having ion permeability and insulating properties. 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] In the example shown in Figure 1, the positive electrode lead 20 is electrically connected to an intermediate part of the positive electrode core, such as the center in the winding direction, and the negative electrode lead 21 is electrically connected to the winding end in the winding direction of the negative electrode core. However, the negative electrode lead may be electrically connected to the winding start end in the winding direction of the negative electrode core. Alternatively, the electrode body may have two negative electrode leads, with one negative electrode lead electrically connected to the winding start end in the winding direction of the negative electrode core, and the other negative electrode lead electrically connected to the winding end in the winding direction of the negative electrode core. Alternatively, the negative electrode lead may be electrically connected to the winding start end in the winding direction of the negative electrode core, and the winding end end in the winding direction of the negative electrode core may be in contact with the inner surface of the outer can. Alternatively, there may be no negative electrode lead, and the negative electrode and the outer can may be electrically connected by bringing the winding end end in the winding direction of the negative electrode core into contact with the inner surface of the outer can.

[0022] The cylindrical battery 10 further includes an insulating plate 18 positioned above the electrode body 14 and an insulating plate 19 positioned below the electrode body 14. The insulating plates 18 and 19 are made of an insulating material, such as resin. In the example shown in Figure 1, the positive electrode lead 20 attached to the positive electrode 11 extends towards the sealing body 17 through a through hole in the insulating plate 18, and the negative electrode lead 21 attached to the negative electrode 12 extends towards the bottom 68 of the outer casing 16, passing outside the insulating plate 19. The positive electrode lead 20 is joined to the lower surface of the terminal plate 23, which is the bottom plate of the sealing body 17, by welding or the like, and the sealing plate 27, which is the top plate of the sealing body 17 and is electrically connected to the terminal plate 23, becomes the positive electrode terminal. The negative electrode lead 21 is connected to the inner surface of the bottom 68 of the outer casing 16 by welding or the like, and the outer casing 16 becomes the negative electrode terminal.

[0023] The outer casing 16 is a bottomed cylindrical metal container. The space between the outer casing 16 and the sealing body 17 is sealed with an annular gasket 28, thereby sealing the internal space of the cylindrical battery 10. The outer casing 16 holds the sealing body 17 via the gasket 28, and the sealing body 17 and the outer casing 16 are insulated from each other. The gasket 28 serves as a sealing material to maintain airtightness inside the battery and as an insulating material to prevent short circuits between the outer casing 16 and the sealing body 17.

[0024] The outer container 16 has a side wall portion 30 and a bottom portion 68. The side wall portion 30 is the portion of the outer container 16 excluding the bottom portion 68, and the side wall portion 30 has a crimping portion 33 and a grooved portion 35 formed therein. The grooved portion 35 is provided in an annular shape on the axial upper side of the side wall portion 30. Specifically, the grooved portion 35 is formed by spinning a part of the side wall portion 30 of the outer container 16 radially inward to create a recess on the radially inward side. The grooved portion 35 protrudes radially inward below the axial direction of the opening and supports the gasket 28. The crimping portion 33 is located above the grooved portion 35 and is formed by bending the end of the opening radially inward so as to extend radially inward from the end of the side wall portion 30 on the opening side. The crimping portion 33 crimps and fixes the sealing body 17 via the gasket 28.

[0025] The sealing body 17 has a structure in which a terminal plate 23, an annular insulating plate 25, and a sealing plate 27 are stacked in order from the electrode body 14 side. Each component constituting the sealing body 17 has a disc shape or a ring shape, and each component except the insulating plate 25 is electrically connected. The terminal plate 23 constitutes the bottom plate of the sealing body 17 and has a circular upper surface located on substantially the same plane. The terminal plate 23 has an annular thick portion 23a located on the radially outward side and a disc-shaped thin portion 23b that is thinner than the thick portion 23a and is connected to the radially inward annular end of the thick portion 23a. The positive electrode lead 20 is connected to the lower surface of the thick portion 23a of the terminal plate 23 by welding or the like.

[0026] The sealing plate 27 is circular in plan view and has a central portion 27a, an outer peripheral portion 27b, and an inclined portion 27c connecting the central portion 27a and the outer peripheral portion 27b. The upper surface of the thin-walled portion 23b of the terminal plate 23 and the lower surface of the central portion 27a of the sealing plate 27 are joined by metallurgical joining, for example, by laser welding. The thickness of the inclined portion 27c is thinner than that of the central portion 27a. The annular upper surface of the inclined portion 27c is an inclined surface that is positioned upward as it moves radially outward, and the annular lower surface of the inclined portion 27c is also an inclined surface that is positioned upward as it moves radially outward. The thickness of the inclined portion 27c decreases as it moves radially outward.

[0027] The insulating plate 25 is fixed by press-fitting into the inner surface of the outer peripheral portion 27b, for example. The insulating plate 25 has an annular projection 25a on its radial outer peripheral side that bends downward in the height direction, and the thickened portion 23a of the terminal plate 23 is fixed by press-fitting into the inner surface of the annular projection 25a, for example. The insulating plate 25 is made of an insulating resin or the like and prevents the thickened portion 23a of the terminal plate 23 from electrically connecting to the sealing plate 27. The insulating plate 25 has one or more ventilation holes 25b that penetrate axially at a location that overlaps axially with the inclined portion 27c of the sealing plate 27, and the terminal plate 23 has one or more ventilation holes 23c that penetrate axially at a location that overlaps axially with the inclined portion 27c and communicate with the ventilation holes 25b.

[0028] When the cylindrical battery 10 overheats and its internal pressure reaches a predetermined value, the central portion 27a and the inclined portion 27c of the sealing plate 27 invert upward, using the radially outward annular end 39, which has low rigidity in the inclined portion 27c, as a fulcrum. Simultaneously with this inversion, the thin-walled portion 23b of the terminal plate 23 breaks, severing the connection between the terminal plate 23 and the sealing plate 27, or the weld between the terminal plate 23 and the sealing plate 27 breaks. This action interrupts the current path between the terminal plate 23 and the sealing plate 27.

[0029] Furthermore, when the internal pressure rises, the annular end 39 of the inclined portion 27c ruptures, and the gas inside the battery is discharged to the outside through the rupture in the sealing plate 27 via the vent holes 23c and 25b. As a result, even if the internal pressure of the cylindrical battery 10 rises, the battery will not rupture, the impact on the equipment in which the cylindrical battery 10 is installed will be suppressed, and safety will be enhanced. The terminal plate 23 constitutes a safety valve, and the inclined portion 27c of the sealing body is a rupture section that discharges the internal gas to the outside when it ruptures.

[0030] Next, the shape of the gasket 28 will be described in detail using Figure 2. Figure 2 is a cross-sectional view of the area around the crimped portion 33 of a cylindrical battery 10, which is an example of an embodiment. As shown in Figure 2, the gasket 28 is placed on the upper surface of the grooved portion 35, and is compressed by the crimped portion 33 by bending the end of the opening of the outer casing 16 radially inward, thereby clamping the sealing body 17. The gasket 28 is an annular member and is manufactured, for example, by injection molding of a resin such as polyethylene or polypropylene.

[0031] The gasket 28 has a recess 60 in the region facing the crimped portion 33. In this embodiment, the crimped portion 33 is located above the side wall portion 30a and refers to the portion from the end of the opening of the outer casing 16 to the lower R-shaped end connecting to the side wall portion 30a. In this specification, "R-shape" refers to a shape connected by a curve represented by an arc in the cross-section of the cylindrical battery 10. Because the gasket 28 has a recess 60 in this region, a space for liquid retention is formed between the gasket 28 and the inner surface of the crimped portion 33 of the outer casing 16. The electrolyte adhering to the inner circumferential surface of the outer casing 16 moves in the direction of arrow A by capillary action through the gap between the gasket 28 and the outer casing 16. When the electrolyte reaches the space formed by the recess 60, the contact area of ​​the electrolyte increases, which disperses the surface tension that was generated on the surface of the electrolyte, and the movement of the electrolyte by capillary action can be suppressed. The inner circumferential surface of the outer casing 16 refers to the inner surface of the side wall portion 30 facing inward, that is, the inner surface of the side wall portion 30a, which is parallel to the axial direction of the outer casing 16. In order to prevent the electrolyte adhering to the inner surface of the side wall portion 30a from moving in the direction of arrow A and seeping out to the outside of the battery, it is preferable that the recess 60 be provided above the area facing the inner surface of the side wall portion 30a.

[0032] The recess 60 may be formed, for example, by machining the gasket 28, but from the viewpoint of mass production, it may also be formed by providing a convex shape in the mold used when injection molding the gasket 28. The depth of the recess 60 in the gasket 28 is preferably 10% to 80% of the thickness of the gasket 28 in the portion located between the sealing body 17 and the crimping portion 33, for example, 0.05 mm to 0.3 mm. The width of the recess 60 is, for example, 0.05 mm to 0.3 mm. The cross-sectional shape of the recess 60 is not particularly limited, but for example, it is V-shaped. The depth, width, and cross-sectional shape of the recess 60 may change in the stretching direction, in which case the depth and width of the recess 60 represent the average value of values ​​measured at multiple points along the stretching direction, but in order to suppress the movement of electrolytes, it is preferable that the depth, width, and cross-sectional shape of the recess 60 be constant in the stretching direction. If the dimensions of each recess 60 are within the specified range, the movement of the electrolyte can be suppressed while maintaining airtightness inside the battery.

[0033] Preferably, the recess 60 is formed only between a position 0.5 mm away from the tip P1 of the crimped portion 33 and the upper end P3 of the crimped portion 33. The battery 10 ensures airtightness inside the battery by compressing the gasket 28 with the crimped portion 33 and the grooved portion 35, thereby making the gasket 28 tightly adhere to the inner surface of the outer casing 16. The area of ​​the crimped portion 33 at a distance L of less than 0.5 mm from the tip P1 is the part where the most force is applied when crimping and fixing the sealing body 17 via the gasket 28. If a recess is provided in the part of the gasket 28 facing this area, not only will the recess not be able to maintain the above dimensions due to the compression of the gasket 28, but the airtightness of the battery 10 cannot be sufficiently ensured. In contrast, if the recess 60 is formed only between a position 0.5 mm away from the tip P1 of the crimped portion 33 and the upper end P3 of the crimped portion 33, that is, between P2, which is 0.5 mm away from P1' where the gasket 28 and the tip P1 of the crimped portion 33 overlap in the axial direction, and P3' where the gasket 28 and the upper end P3 of the crimped portion 33 overlap in the axial direction, then the tight seal between the tip of the crimped portion 33 and the gasket 28 is ensured, thereby maintaining airtightness inside the battery while suppressing the movement of the electrolyte. Note that the tip of the crimped portion 33 may have a right-angled cross-sectional shape as shown in Figure 3, or it may have a rounded R shape, depending on the processing method, but in either case, the tip P1 of the crimped portion 33 refers to the point of the crimped portion 33 that is radially inward.

[0034] Preferably, the recess 60 is not provided outside the upper end P3 of the crimping portion 33, that is, in the region radially outside P3' where the gasket 28 and the upper end P3 of the crimping portion 33 overlap in the axial direction, nor in the region facing the inner surface of the side wall portion 30a. When the bottom 68 of the cylindrical battery 10 is oriented vertically downward, the electrolyte, subjected to gravity in the vertical direction, accumulates in the recess provided in that region, and the electrolyte adhering to the inner circumferential surface of the outer casing 16 concentrates and comes into contact with the inner surface of the outer casing 16. As a result, the electrolyte reacts with moisture that has entered from the outside to produce hydrofluoric acid, which corrodes the outer casing 16 and increases the likelihood of holes forming in the outer casing 16. In contrast, when a recess 60 of the above dimensions is provided at a predetermined position in the region of the gasket 28 facing the crimping portion 33, the electrolyte accumulates vertically downward in the recess 60, so the electrolyte does not come into contact with the inner surface of the outer casing 16, and corrosion of the outer casing 16 can be suppressed.

[0035] The recess 60 is preferably formed in an annular shape along the circumferential direction of the gasket 28. An annular shape along the circumferential direction of the gasket 28 is preferable, for example, a circular shape in plan view, but it may also have an elliptical shape, a polygonal shape, or other shapes. By forming the recess 60 in an annular shape, a liquid-retaining space is formed around the entire circumferential direction in the small gap between the gasket 28 and the inner surface of the outer can 16, thereby more reliably suppressing the movement of the electrolyte in that gap.

[0036] From the viewpoint of maintaining airtightness inside the battery, it is preferable to form one annular recess 60 whose dimensions are within the above range. If the gasket 28 has multiple annular grooves, the strength of the gasket 28 cannot be ensured, causing deformation and making it difficult to maintain airtightness inside the battery. If the gasket 28 has multiple annular grooves with small cross-sectional areas in order to maintain airtightness inside the battery, the space formed by one groove is narrow, so the surface tension generated at the surface of the electrolyte that has reached it is not sufficiently dispersed, and the movement of the electrolyte due to capillary action is not sufficiently suppressed.

[0037] This disclosure is not limited to the above embodiments and their modifications, and various improvements and modifications are possible within the scope of the claims of this application and their equivalents. For example, the above embodiments describe a case in which the sealing body 17 does not have a rupture plate that bursts when the pressure inside the battery reaches a set pressure and temperature. However, the sealing body may include 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 consist only of rupture plates. Alternatively, the sealing body may have a structure in which an internal terminal plate, an insulating plate, and a rupture plate are stacked in order from the electrode body side.

[0038] The cylindrical battery of this disclosure may have the following configurations: Configuration 1: A cylindrical battery comprising an electrode body in which a positive electrode and a negative electrode are wound with a separator between them, an electrolyte, a bottomed cylindrical outer casing containing the electrode body and the electrolyte, a sealing body that closes an opening provided at the top of the outer casing, and a gasket interposed between the outer casing and the sealing body, wherein the outer casing has a grooved portion that protrudes radially inward below the opening to support the gasket, and a crimping portion that bends the end of the opening radially inward to crimp and fix the sealing body via the gasket, and the gasket has a recess in a region facing the crimping portion. Configuration 2: The cylindrical battery according to Configuration 1, wherein the depth of the recess is 10% or more and 80% or less of the thickness of the gasket in the portion located between the sealing body and the crimping portion. Configuration 3: The cylindrical battery according to Configuration 1 or 2, wherein the recess is formed only between a position 0.5 mm away from the tip of the crimped portion and the upper end of the crimped portion. Configuration 4: The cylindrical battery according to any one of Configurations 1 to 3, wherein the recess is formed in an annular shape along the circumferential direction of the gasket.

[0039] 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16 Outer casing, 17 Sealing body, 18, 19, 25 Insulating plate, 20 Positive electrode lead, 21 Negative electrode lead, 23 Terminal plate, 23a Thick-walled section, 23b Thin-walled section, 23c Ventilation hole, 25a Annular projection, 25b Ventilation hole, 27 Sealing plate, 27a Central section, 27b Outer periphery, 27c Inclined section, 28 Gasket, 30 Side wall section, 33 Crimping section, 35 Grooved section, 60 Recessed section, 68 Bottom section,

Claims

1. A cylindrical battery comprising: an electrode body in which a positive electrode and a negative electrode are wound with a separator between them; an electrolyte; a bottomed cylindrical outer casing containing the electrode body and the electrolyte; a sealing body that closes an opening provided at the top of the outer casing; and a gasket interposed between the outer casing and the sealing body, wherein the outer casing has a grooved portion that protrudes radially inward below the opening to support the gasket, and a crimping portion that bends the end of the opening radially inward to crimp and fix the sealing body via the gasket, and the gasket has a recess in the region opposite to the crimping portion.

2. The cylindrical battery according to claim 1, wherein the depth of the recess is 10% or more and 80% or less of the thickness of the gasket in the portion located between the sealing body and the crimped portion.

3. The cylindrical battery according to claim 1, wherein the recess is formed only between a position 0.5 mm away from the tip of the crimped portion and the upper end of the crimped portion.

4. The cylindrical battery according to claim 1, wherein the recess is formed in an annular shape along the circumferential direction of the gasket.

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