Cylindrical battery

Abstract

A cylindrical battery (10) is provided with: an electrode body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; an electrolytic solution; a bottomed cylindrical outer can (16) that accommodates the electrode body and the electrolytic solution; a sealing body (17) that closes an opening portion provided in the upper portion of the outer can (16); and a gasket (28) interposed between the outer can (16) and the sealing body (17). The outer can (16) comprises: a grooved portion (35) that protrudes radially inward below the opening portion in the axial direction and supports the gasket (28); and a crimped portion (33) that is positioned above the grooved portion (35), and crimps and fixes the sealing body (17) via the gasket (28) by bending an end portion of the opening portion radially inward. The gasket (28) comprises a groove (60) in at least one of a first region (61) facing the inner peripheral surface of the outer can (16) and a second region (62) facing the grooved portion (35).

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 has been 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 may adhere to the inner surface of the outer can. When the electrolytic solution adhering to the inner surface of the outer can intervenes between the outer can and the gasket during battery assembly, the electrolytic solution may move through the gap and leak to the outside, causing 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 Patent Application Laid-Open No. 2007-184270

[0005] However, even when an adhesive substance is inserted into the gap between the outer can and the gasket, a slight gap may exist between the adhesive substance and the outer can or between the adhesive substance and the gasket. Therefore, due to the cohesive force between the electrolytic solution molecules and the capillary phenomenon, the electrolytic solution may move through the gap, resulting in the possibility of liquid leakage. For this reason, 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 with a separator interposed therebetween, 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 at the upper part of the outer can, and a gasket interposed between the outer can and the sealing body. The outer can has a groove portion that protrudes radially inward below the opening in the axial direction to support the gasket, and a caulking portion that is located above the groove portion and bends the end portion of the opening radially inward to caulking and fix the sealing body through the gasket. The gasket has a groove in at least one of a first region facing the inner peripheral surface of the outer can and a second region facing the groove 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 an axial cross-sectional view of a cylindrical battery, which is one example of an embodiment. This is a cross-sectional view of the area around the crimped portion of a cylindrical battery, which is one example of an embodiment. This is a cross-sectional view of the area around the crimped portion of a cylindrical battery, which is another 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 includes a first region 61 which faces the inner circumferential surface of the outer can 16 and a second region 62 which faces the grooved portion 35. The inner circumferential surface of the outer can 16 refers to the inner surface of the side wall portion 30 facing inward of the outer can 16, which is parallel to the axial direction of the outer can 16. The first region 61 of the gasket 28 faces the portion of the inner circumferential surface of the outer can 16 located between the crimped portion 33 and the grooved portion 35. The inner surfaces of the crimped portion 33 and the grooved portion 35 each have an R shape that connects to the inner circumferential surface of the side wall portion 30a. In this specification, "R shape" refers to a shape connected by a curve represented by a circular arc in the cross-section of the cylindrical battery 10. In other words, the first region 61 is the portion of the outer circumferential surface of the gasket 28 that faces the inner circumferential surface of the outer can 16, located between the R-shaped lower end P1 of the crimping portion 33 and the R-shaped upper end P2 of the grooved portion 35. The second region 62 is the portion of the gasket 28 that faces the inner surface of the outer can 16, located between P2, which is the R-shaped upper end of the upper surface of the grooved portion 35, and P3, which is the lower end of the portion that contacts the gasket 28.

[0032] The gasket 28 has grooves 60 in at least one of the first region 61 and the second region 62. The presence of grooves 60 in the gasket 28 creates a liquid reservoir space in the small gap between the gasket 28 and the inner surface of the outer can 16. The electrolyte adhering to the inner surface of the outer can 16 moves in the direction of arrow A by capillary action through the gap between the gasket 28 and the outer can 16. When the electrolyte reaches the space formed by the grooves 60, the contact area of ​​the electrolyte increases, which disperses the surface tension that was generated on the surface of the electrolyte, thereby suppressing the movement of the electrolyte by capillary action.

[0033] The groove 60 is formed, for example, by providing a convex shape to the mold when injection molding the gasket 28. The depth of the groove 60 provided in the first region 61 of the gasket 28 is, for example, 0.05 mm or more and 0.3 mm or less, and the depth of the groove 60 provided in the second region 62 is, for example, 0.02 mm or less. From the viewpoint of maintaining airtightness inside the battery, the groove 60 provided in the second region 62 facing the grooved portion 35 is formed shallower than the groove 60 provided in the first region 61. 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. When the depth dimension of the groove 60 provided in the second region 62 of the gasket 28 is within this range, the tight adhesion between the second region 62 and the grooved portion 35 is ensured, and thus airtightness inside the battery is maintained.

[0034] The width of the groove 60 provided in the first region 61 of the gasket 28 is, for example, 0.05 mm or more and 0.3 mm or less. The width of the groove 60 provided in the second region 62 of the gasket 28 is, for example, 0.05 mm or more and 0.5 mm or less. The cross-sectional shape of the groove 60 is not particularly limited, but for example, it is V-shaped. The depth, width, and cross-sectional shape of the groove 60 may change in the stretching direction, in which case the depth and width of the groove 60 represent the average value of values ​​measured at multiple points along the stretching direction, but in order to suppress the movement of the electrolyte, it is preferable that the depth, width, and cross-sectional shape of the groove 60 be constant in the stretching direction. If each dimension of the groove 60 is within the said range, it is possible to suppress the movement of the electrolyte while maintaining airtightness inside the battery.

[0035] It is preferable that the grooves 60 are formed in a continuous annular shape. By forming the grooves 60 in a continuous annular shape, a liquid reservoir space is formed around the entire circumference 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 the gap.

[0036] From the viewpoint of maintaining airtightness inside the battery, it is preferable to form one annular groove 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 on 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] Of the gasket 28, at least a portion of the part above the first region 61 is compressed and deformed when the sealing body 17 is crimped and fixed. Therefore, it is preferable that the groove 60 be provided in at least one of the first region 61 and the second region 62 of the gasket 28, where the possibility of deformation is low and sufficient airtightness inside the battery can be maintained.

[0038] It is more preferable that the groove 60 be formed in the first region 61. When the bottom 68 of the cylindrical battery 10 is positioned vertically downward, the first region 61 is located vertically, and the portion of the second region 62 that corresponds to the upper surface of the grooved portion 35 is located horizontally. When the electrolyte reaches the groove 60 formed in that portion of the second region 62, the electrolyte is subjected to gravity in the vertical direction and does not remain sufficiently in the space formed by the groove 60, and may move along the inner surface of the outer casing 16 in the direction of arrow A. In contrast, when the groove 60 is formed in the first region 61 which is located vertically, the electrolyte that reaches the groove 60 is subjected to gravity in the vertical direction and remains in the space formed by the groove 60, thus more reliably suppressing the movement of the electrolyte.

[0039] Next, the case in which the outer casing 16 has a second groove 70 will be described in detail with reference to Figure 3. Figure 3 is a cross-sectional view of the crimped portion of a cylindrical battery, which is another example of the embodiment. The outer casing 16 has a second groove 70 on its inner circumferential surface facing the first region 61 of the gasket 28.

[0040] The second groove 70 is formed by cutting or other machining the inner surface of the inner circumferential surface of the outer can 16, i.e., the inner surface of the side wall portion 30a, which faces the first region 61 of the gasket 28. The depth of the groove 70 is, for example, 0.05 mm or more and 0.1 mm or less, and the width of the groove 70 is, for example, 0.05 mm or more and 0.3 mm or less. The cross-sectional shape of the groove 70 is not particularly limited, but for example, it is V-shaped. The depth, width, and cross-sectional shape of the groove 70 may change in the stretching direction, in which case the depth and width of the groove 70 represent the average value of values ​​measured at multiple points along the stretching direction, but in order to suppress the movement of the electrolyte, it is preferable that the depth, width, and cross-sectional shape of the groove 70 be constant in the stretching direction. If each dimension of the groove 70 is within the said range, the movement of the electrolyte can be suppressed while ensuring the strength of the outer can 16.

[0041] It is preferable that the groove 70 is not provided on the inner surface of the grooved portion 35 facing the second region 62 of the gasket 28. 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 attached to the inner surface of the outer casing 16. If a groove is provided on the inner surface of the grooved portion 35 facing the second region 62, a wider space will exist between the compressed gasket 28 and the grooved portion 35 compared to the case where the groove 60 is provided in the second region 62 of the gasket 28, so that sufficient airtightness inside the battery cannot be ensured. For this reason, it is preferable that the groove 70 is not provided on the inner surface of the grooved portion 35 facing the second region 62.

[0042] The grooves 70 may be formed intermittently in the circumferential direction of the gasket 28, but it is preferable that they be formed continuously in an annular shape. By forming the grooves 70 continuously in an annular shape, a liquid reservoir space is formed around the entire circumference 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 the gap.

[0043] Since the gasket 28 has the groove 60 at a predetermined position and the outer can 16 has the second groove 70, a space for storing liquid can be added in the small gap between the gasket 28 and the outer can 16. As the space for retaining the electrolytic solution moving in the direction of arrow A between the gasket 28 and the outer can 16 increases, the movement of the electrolytic solution can be more reliably suppressed.

[0044] When the groove 60 is provided in the first region 61, the groove 60 and the groove 70 may be provided at positions facing each other. When the groove 60 and the groove 70 are provided at positions facing each other, a wider space for retaining the electrolytic solution moving in the gap between the first region 61 of the gasket 28 and the outer can 16 is formed as compared with the case where the groove 60 and the groove 70 do not face each other. When the electrolytic solution moving in the direction of arrow A reaches the space formed by the groove 60 and the groove 70, the surface tension generated on the liquid surface of the electrolytic solution is dispersed by the further increase in the contact portion of the electrolytic solution as compared with the case where the groove 60 and the groove 70 do not face each other, and the movement of the electrolytic solution due to the capillary phenomenon can be more effectively suppressed. However, when the groove 60 and the groove 70 face each other, many portions that are not in close contact between the gasket 28 and the outer can 16 will exist, so that the airtightness inside the battery cannot be sufficiently ensured.

[0045] When the groove 60 is provided in the first region 61, it is more preferable that the groove 60 and the groove 70 are provided at positions not facing each other. When the groove 60 and the groove 70 are provided at positions not facing each other, the respective spaces for retaining the electrolytic solution moving in the gap between the gasket 28 and the outer can 16 become smaller as compared with the case where the groove 60 and the groove 70 face each other, but the other groove provided above functions as a preliminary liquid storage space with respect to the one groove provided below. In this case, while ensuring the airtightness inside the battery and the strength of the outer can 16, the movement of the electrolytic solution can be more reliably suppressed.

[0046] Note that the present disclosure is not limited to the above-described embodiments and their modifications, and various improvements and changes can be made within the scope of the matters described in the claims of the present application and their equivalent scope. For example, in the above embodiment, the case where the groove 60 formed in the gasket 28 is continuously formed in a ring shape has been described. However, a plurality of grooves 60 may be formed intermittently in the circumferential direction. In this case, it is preferable that the groove 60 is provided in at least 50%, preferably 80%, more preferably 90% of the circumferential length of the gasket 28. The plurality of grooves 60 may be formed intermittently irregularly, but are more preferably formed at equal intervals.

[0047] The cylindrical battery of the present disclosure may have the following configuration. Configuration 1: An electrode body in which a positive electrode and a negative electrode are wound via 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 at the upper part of the outer can, and a gasket interposed between the outer can and the sealing body. The outer can has a groove portion that protrudes radially inward below the opening in the axial direction to support the gasket, and a caulking portion that is located above the groove portion and bends the end portion of the opening radially inward to caulk and fix the sealing body via the gasket. The gasket has a groove in at least one of a first region facing the inner peripheral surface of the outer can and a second region facing the groove portion. Configuration 2: The cylindrical battery according to Configuration 1, wherein the gasket has a groove in the first region. Configuration 3: The cylindrical battery according to Configuration 1 or 2, wherein the outer can has a second groove in the inner peripheral surface facing the first region of the gasket.

[0048] 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16 Outer can, 17 Sealing body, 18, 19, 25 Insulating plate, 20 Positive electrode lead, 21 Negative electrode lead, 23 Terminal plate, 23a Thick portion, 23b Thin portion, 23c Vent hole, 25a Annular protrusion, 25b Vent hole, 27 Sealing plate, 27a Central portion, 27b Outer peripheral portion, 27c Inclined portion, 28 Gasket, 30 Side wall portion, 33 Caulking portion, 35 Groove portion, 60 Groove, 61 First region, 62 Second region, 63 Contact point, 68 Bottom, 70 Groove

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 axially below the opening and supports the gasket, and a crimping portion located above the grooved portion that bends the end of the opening radially inward and crimps and fixes the sealing body via the gasket, and the gasket has grooves in at least one of a first region facing the inner circumferential surface of the outer casing and a second region facing the grooved portion.

2. The cylindrical battery according to claim 1, wherein the gasket has a groove in the first region.

3. The cylindrical battery according to claim 1, wherein the outer casing has a second groove on the inner circumferential surface facing the first region of the gasket.

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