Cylindrical battery and manufacturing method for cylindrical battery

Abstract

This cylindrical battery comprises: an electrode body that has a positive electrode, a negative electrode, and a separator, and that is formed via the positive electrode and the negative electrode being wound with the separator therebetween; an outer can (15) that stores the electrode body and that has a bottomed cylinder shape; a sealing body (17) that blocks an opening of the outer can (15); and a gasket (30) that is disposed between the outer can (15) and the sealing body (17) and that has a ring shape in plan view. A recess (34) that spans the entire circumference is provided to a surface of the gasket (30) which faces a side surface of the sealing body (17). The recess (34) is provided so as to cover the edge of the sealing body (17) on the outer can (15) opening side. A movement restriction part (35) where the recess (34) is not formed is provided on the outer can (15) bottom side of the region of the gasket (30) which faces the side surface of the sealing body (17).

Description

Cylindrical Battery and Method for Manufacturing the Same

[0001] The present disclosure relates to a cylindrical battery and a method for manufacturing the same, and particularly to the structure of a gasket that insulatively supports a sealing body with respect to an outer can.

[0002] Generally, a cylindrical battery includes an electrode body, an outer can that houses the electrode body, and a sealing body that closes an opening of the outer can, and has a structure in which a gasket is disposed between the outer can and the sealing body (for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2001-28259

[0004] In order to seal the inside of the outer can, the sealing body is fixed to the outer can via a gasket by caulking the opening side of the outer can inward in the radial direction. In order to obtain sufficient sealing performance in this caulking process, a large load is applied to the end portion of the sealing plate. However, at that time, if the rigidity of the sealing plate is low, the sealing plate is deformed, resulting in a deterioration of battery performance such as a fluctuation in the operating pressure of a current interruption mechanism or the like.

[0005] Against such a background, by widening the gap between the gasket and the sealing body, those problems can be avoided. However, by widening the gap between the gasket and the sealing body, there is a problem that the sealing body is displaced in the radial direction of the outer can due to the radial force applied to the sealing body and the gasket during caulking fixation. When the sealing body is displaced, the sealing performance deteriorates in a part between the sealing body and the gasket. Even the cylindrical battery described in Patent Document 1 cannot solve such problems.

[0006] The cylindrical battery according to this disclosure comprises an electrode body having a positive electrode, a negative electrode, and a separator, formed by winding the positive electrode and the negative electrode with the separator in between; a bottomed cylindrical outer casing for housing the electrode body; a sealing body that closes the opening of the outer casing; and a gasket having a ring shape in plan view disposed between the outer casing and the sealing body, wherein a recess is formed around the entire circumference of the surface of the gasket facing the side surface of the sealing body, the recess is provided to cover the edge of the sealing body on the opening side of the outer casing, and a movement-restricting portion is formed on the bottom side of the outer casing in the region of the gasket facing the side surface of the sealing body, where the recess is not formed.

[0007] According to the cylindrical battery and the method for manufacturing the cylindrical battery described herein, it is possible to suppress deterioration of sealing performance while suppressing the reduction in battery performance due to deformation of the sealing body.

[0008] This is an axial cross-sectional view of a cylindrical battery, which is an example of an embodiment. This is an enlarged view of part A in Figure 1. This is an enlarged view of part B in Figure 2. This is an enlarged view of part B in Figure 2, showing the state before crimping and fixing. This is a diagram showing another example of Figure 4.

[0009] Hereinafter, an example of an embodiment of the cylindrical battery according to this disclosure will be described in detail with reference to the drawings. The cylindrical battery of this disclosure may be a primary battery or a secondary battery. It may also be a battery using an aqueous electrolyte or a battery using a non-aqueous electrolyte. In the following, a non-aqueous electrolyte secondary battery (lithium-ion battery) using a non-aqueous electrolyte will be given as an example of a cylindrical battery 10, which is one embodiment, but the cylindrical battery of this disclosure is not limited to this. Furthermore, configurations obtained by selectively combining the components of the multiple embodiments and modified examples described below are included in the scope of this disclosure.

[0010] Figure 1 is a 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 bottomed cylindrical outer casing 15 that houses the electrode body 14, and a sealing body 17 that closes the opening of the outer casing 15. The cylindrical battery 10 contains an electrolyte, which is housed in the outer casing 15 together with the electrode body 14. The cylindrical battery 10 further includes a ring-shaped gasket 30 interposed between the outer casing 15 and the sealing body 17 to ensure airtightness inside the battery and to prevent electrical contact between the outer casing 15 and the sealing body 17.

[0011] The electrode body 14 has a positive electrode 11, a negative electrode 12, and a separator 13, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound in a spiral shape via the separator 13. The positive electrode 11, the negative electrode 12, and the separator 13 are all elongated strip-shaped bodies, and are alternately stacked in the radial direction of the electrode body 14 by being wound in a spiral shape. The negative electrode 12 is formed to be slightly larger in dimensions than the positive electrode 11 in order to prevent lithium deposition. That is, the negative electrode 12 is formed to be longer in the longitudinal direction and the width direction (short direction) than the positive electrode 11. The separator 13 is formed to be at least slightly larger in dimensions than the positive electrode 11, and two separators are arranged so as to sandwich the positive electrode 11.

[0012] The outer casing 15 is a bottomed cylindrical metal container that houses the electrode body 14 and the electrolyte. A groove 16 is formed on the side of the outer casing 15, extending circumferentially and protruding radially inward. The radial length of the groove 16 on the outer casing 15 is preferably such that it does not come into contact with the positive electrode lead 20 extending from the electrode body 14. For the sake of explanation, the sealing body 17 side of the cylindrical battery 10 will be considered the top, and the bottom side of the outer casing 15 will be considered the bottom. The groove 16 is preferably formed in an annular shape along the circumferential direction of the outer casing 15, and its upper surface supports the sealing body 17. The sealing body 17 and gasket 30 are fixed to the upper part of the outer casing 15 by the groove 16 and the open end of the outer casing 15 which is crimped to the sealing body 17 and gasket 30. The opening of the outer can 15 is circular in plan view, and the sealing body 17 is similarly circular in plan view.

[0013] The electrolyte may be an aqueous electrolyte, but in this embodiment, a non-aqueous electrolyte is used. The non-aqueous electrolyte has lithium-ion conductivity. The non-aqueous electrolyte may be a liquid electrolyte (electrolyte solution) or a solid electrolyte. The cylindrical battery 10 is a non-aqueous electrolyte secondary battery, and among these, a lithium-ion battery is preferred.

[0014] A liquid electrolyte (electrolyte solution) comprises 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. The non-aqueous solvent may also contain halogen-substituted solvents (e.g., fluoroethylene carbonate) in which at least some of the hydrogen atoms in the solvent are replaced with halogen atoms such as fluorine. Examples of electrolyte salts include LiPF4. ６ Lithium salts such as these are used.

[0015] As the solid electrolyte, for example, a solid or gel-like polymer electrolyte, an inorganic solid electrolyte, etc., can be used. As the inorganic solid electrolyte, materials known for all-solid-state lithium-ion secondary batteries, etc. (for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, halogen-based solid electrolytes, etc.) can be used. The polymer electrolyte includes, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt and a matrix polymer. As the matrix polymer, for example, a polymer material that absorbs a non-aqueous solvent and gels is used. Examples of polymer materials include fluororesins, acrylic resins, polyethers, etc.

[0016] The positive electrode 11 comprises a long positive electrode core and a positive electrode mixture layer provided on the positive electrode core. The positive electrode core can be made of a metal foil that is stable within the potential range of the positive electrode 11, such as aluminum, aluminum alloy, stainless steel, or titanium, or a film with the metal arranged on its surface. The positive electrode mixture layer contains a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride (PVdF), and is preferably formed on both sides of the positive electrode core except for the portion to which the positive electrode lead 20 described later is connected. For example, a lithium transition metal composite oxide containing Ni, Co, Mn, Al, etc., can be used as the positive electrode active material.

[0017] The negative electrode 12 comprises a long negative electrode core and a negative electrode mixture layer provided on the negative electrode core. The negative electrode core can be made of a metal foil that is stable within the potential range of the negative electrode 12, such as copper, copper alloy, stainless steel, nickel, or nickel 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 such as styrene-butadiene rubber (SBR), and is preferably formed on both sides of the negative electrode core except for the portion to which the negative electrode lead 21 described later is connected. For example, graphite or a Si-containing material can be used as the negative electrode active material.

[0018] 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. Suitable materials for the separator 13 (porous sheet) include polyethylene, polyolefins such as polypropylene, and cellulose. The separator 13 may have a single-layer structure or a multi-layer structure. In addition, a highly heat-resistant resin layer, such as aramid resin, may be formed on the surface of the separator 13.

[0019] The electrode body 14 further includes a positive electrode lead 20 connected to the core of the positive electrode 11 by welding or the like, and a negative electrode lead 21 connected to the core of the negative electrode 12 by welding or the like. In addition, insulating plates 22 and 23 are arranged above and below the electrode body 14, respectively. In the example shown in Figure 1, the positive electrode lead 20 extends towards the sealing body 17 through a through hole in the insulating plate 22, and the negative electrode lead 21 extends towards the bottom of the outer can 15 through the outside of the insulating plate 23. In this embodiment, the positive electrode lead 20 is connected to the lower surface of the sealing body 17 by welding or the like, so that the sealing body 17 becomes the positive electrode external terminal, and the negative electrode lead 21 is connected to the inner bottom surface of the outer can 15 by welding or the like, so that the outer can 15 becomes the negative electrode external terminal.

[0020] The outer container 15 is a bottomed cylindrical metal container with one end open in the axial direction, and the opening of the outer container 15 is sealed by a sealing body 17 via a gasket 30. The constituent material of the outer container 15 is not particularly limited, but stainless steel is one example of a preferred constituent material.

[0021] Referring further to Figure 2, a sealing body 17 of a cylindrical battery 10, which is an example of an embodiment, will be described in detail. Figure 2 is an enlarged view of part A in Figure 1.

[0022] As shown in Figure 2, the sealing body 17 has a structure in which an internal terminal plate 24, an annular insulating plate 25, and a sealing plate 26 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 annular insulating plate 25 is electrically connected.

[0023] The sealing plate 26 has a circular shape in plan view. The sealing plate 26 can be manufactured, for example, by press-forming a sheet of aluminum or an aluminum alloy. Aluminum and aluminum alloys are preferred materials for the sealing plate 26, which functions as an explosion-proof valve, because they have excellent flexibility. The sealing plate 26 has a central portion 26a, an outer peripheral portion 26b, and an inclined portion 26c connecting the central portion 26a and the outer peripheral portion 26b. The upper surface of the thin-walled portion 24a of the internal terminal plate 24 and the lower surface of the central portion 26a of the sealing plate 26 are joined, for example, by laser welding.

[0024] The outer periphery 26b is a region located radially outward of the sealing plate 26 and is crimped and fixed to the outer can 15 via the gasket 30. In this embodiment, the outer periphery 26b of the sealing plate 26 becomes the outer periphery 17a of the sealing body 17. The outer periphery 17a of the sealing body 17 may consist of multiple members. For example, if the sealing body 17 has multiple members having similar diameters, including the sealing plate, and each member is stacked and crimped, the outer periphery of the crimped member becomes the outer periphery 17a of the sealing body 17.

[0025] The thickness of the inclined portion 26c is thinner than that of the central portion 26a. The lower surface of the inclined portion 26c is located above the lower surface of the central portion 26a and is connected to the lower surface of the central portion 26a via the annular groove 27. The annular upper surface of the inclined portion 26c is an inclined surface that is located higher as it moves radially outward, and the annular lower surface of the inclined portion 26c is also an inclined surface that is located higher as it moves radially outward. The thickness of the inclined portion 26c decreases as it moves radially outward.

[0026] The annular insulating plate 25 is fixed, for example, by press-fitting it onto the outer surface of the annular groove 27. The annular insulating plate 25 is provided to ensure insulation and prevents the radially outer end of the internal terminal plate 24 from being electrically connected to the sealing plate 26. The annular insulating plate 25 has one or more ventilation holes 25a that penetrate in the height direction at a location that overlaps with the inclined portion 26c of the sealing plate 26 in the height direction, and the internal terminal plate 24 has one or more ventilation holes 24b that penetrate in the height direction at a location that overlaps with the inclined portion 26c in the height direction and communicates with the ventilation holes 25a.

[0027] According to the configuration of the sealing body 17 described above, when the internal pressure of the cylindrical battery 10 reaches a predetermined value, current interruption and gas release can be performed. Specifically, when the internal pressure of the cylindrical battery 10 reaches a predetermined value, the central part 26a and the inclined part 26c of the sealing plate 26 invert upward in the height direction, using the radially outward annular end 26d, which has low rigidity in the inclined part 26c, as a fulcrum. Simultaneously with this inversion, the thin-walled part 24a of the internal terminal plate 24 breaks, separating the part connected from the internal terminal plate 24 to the sealing plate 26, or the weld between the internal terminal plate 24 and the sealing plate 26 comes undone. This action interrupts the current path between the internal terminal plate 24 and the sealing plate 26. Furthermore, as the internal pressure rises, the annular end 26d of the inclined part 26c breaks, and the gas inside the battery is discharged to the outside through the vent holes 24b and 25a from the broken part of the sealing plate 26. This prevents the cylindrical battery 10 from rupturing even if its internal pressure increases.

[0028] As shown in Figures 1 and 2, the gasket 30 is a sealing member positioned on the opening side of the outer can 15, between the sealing body 17 and the outer can 15. The annular gasket 30 seals the space between the outer can 15 and the sealing body 17, thereby sealing the internal space of the outer can 15. The gasket 30 also insulates the sealing body 17 from the outer can 15. In other words, the gasket 30 serves as a sealing material to maintain airtightness inside the battery and as an insulating material to prevent short circuits between the outer can 15 and the sealing body 17.

[0029] The gasket 30 is fixed to the upper end of the outer can 15 by the grooved portion 16 of the outer can 15 and the crimped portion 18 of the opening edge of the outer can 15 which is crimped to the sealing body 17 and the gasket 30. After crimping and fixing, the gasket 30 is positioned between the sealing body 17 and the crimped portion 18, and between the sealing body 17 and the grooved portion 16.

[0030] The gasket 30 has a ring shape in plan view. As shown in Figure 2, the gasket 30 is located between the sealing body 17 and the grooved portion 16, and has a lower annular portion 31 which is crimped and fixed by the crimping portion 18 and the grooved portion 16. The gasket 30 also has a side portion 32 that extends upward from the lower annular portion 31 and is located between the sealing body 17 and the outer can 15, and an upper annular portion 33 that extends radially inward from the side portion 32. A part of the upper annular portion 33 is located between the outer can 15 and the sealing body 17.

[0031] The crimped portion 18 is formed by bending the opening edge of the outer can 15 radially inward, and together with the grooved portion 16, it clamps the sealing body 17 and the gasket 30 from both sides in the thickness direction. Preferably, the length of the crimped portion 18 along the radial direction of the outer can 15 is shorter than the length of the grooved portion 16 along the radial direction of the outer can 15. In other words, the tip position of the grooved portion 16 is located radially inward of the outer can 15 than the tip position of the crimped portion 18. Also, preferably, the length of the crimped portion 18 along the radial direction of the outer can 15 is shorter than the length of the gasket 30 along the radial direction of the outer can 15. In other words, the tip position of the gasket 30 is located radially inward of the outer can 15 than the tip position of the crimped portion 18.

[0032] The recess 34 and movement-restricting portion 35 of the gasket 30 will be described in detail with further reference to Figure 3. Figure 3 is an enlarged view of portion B in Figure 2. In this embodiment, the upper surface 26x and lower surface 26y of the outer peripheral portion 26b of the sealing plate 26 become the upper surface 17x and lower surface 17y of the outer peripheral portion 17a of the sealing body 17.

[0033] A recess 34 is formed around the entire circumference of the surface of the gasket 30 facing the side surface of the sealing body 17. As shown in Figure 3, the recess 34 is provided to cover the upper edge of the sealing body 17 (the opening side of the outer can 15). In addition, a movement-restricting portion 35 is formed on the bottom side of the outer can 15 in the region of the radial inner surface of the gasket 30 that faces the sealing body 17, and where the recess 34 is not formed. The movement-restricting portion 35 suppresses the movement of the sealing body 17 during crimping, thereby suppressing deterioration of the sealing performance between the sealing body 17 and the gasket 30.

[0034] As described above, the recess 34 after crimping is formed to cover the upper edge of the sealing body 17. Preferably, the recess 34 is formed so that the upper edge of the sealing body 17 does not come into contact with the gasket 30. With the recess 34 having the above configuration, the force applied to the sealing body 17 in the radial direction during crimping is less likely to be transmitted to the sealing body 17, and deformation of the sealing body 17 can be suppressed more effectively.

[0035] The upper end 34x of the recess 34 (on the opening side of the outer can 15) before the opening end of the outer can 15 is crimped is formed offset toward the opening side of the outer can 15 compared to the upper surface of the outer peripheral portion 17a of the sealing body 17. As a result, after crimping and fixing, the recess 34 is provided so as to cover the upper edge of the sealing body 17. That is, after crimping and fixing, the recess 34 is formed on the inner surface of the side portion 32 and the upper annular portion 33 of the gasket 30. By forming the recess 34 in the gasket 30, the force applied to the outer can 15 in the radial direction during crimping and fixing can be suppressed, thereby suppressing deformation of the sealing body 17.

[0036] The lower end 34y of the recess 34 (the bottom side of the outer can 15) is located in the region between the lower surface 17y and the upper surface 17x of the outer peripheral portion 17a of the sealing body 17. This creates a movement-restricting portion 35 on the inner surface of the gasket 30, where the recess 34 is not formed on the lower side of the region facing the side surface of the sealing body 17. The formation of the movement-restricting portion 35 suppresses the movement of the sealing body 17 due to the radial force applied to it during crimping. As a result, it is possible to suppress the radial displacement of the sealing body 17 in the outer can 15, thereby suppressing deterioration of the sealing performance of the sealing body 17. The end 34y is formed, for example, shifted toward the opening side of the outer can 15 from a position 50% of the thickness of the outer peripheral portion 17a of the sealing body 17.

[0037] The radial depth of the recess 34 is preferably 0.01 mm or more and 50% or less of the thickness of the gasket 30. In other words, it is preferable that the radial dimension of the gasket 30 in the recess 34 (specifically, the horizontal length of the lower end 34y of the recess 34 in Figure 3) is within the above range. As a result, the radial force applied to the sealing body 17 during crimping is suppressed, and deformation of the sealing body 17 can be effectively suppressed.

[0038] The movement-restricting portion 35 is formed in the lower region of the radially inner surface of the gasket 30. More specifically, the movement-restricting portion 35 is formed in the region facing the side surface of the sealing body 17 and in the region below the recess 34. In the example shown in Figure 3, the movement-restricting portion 35 is a surface parallel to the side surface of the sealing body 17. The shape of the movement-restricting portion 35 is not particularly limited as long as it has a structure that can suppress the movement of the sealing body 17, and may have a shape that protrudes radially inward from the gasket 30. When the movement-restricting portion 35 is a surface parallel to the side surface of the sealing body 17, the contact area with the sealing body 17 increases, so the movement of the sealing body 17 can be effectively suppressed.

[0039] The movement-restricting portion 35 is preferably formed to abut against the side surface of the sealing body 17. That is, the diameter of the movement-restricting portion 35 is preferably the same as the diameter of the sealing body 17. More specifically, the movement-restricting portion 35 is preferably the same diameter as the sealing body 17 or slightly smaller than the diameter of the sealing body 17. As a result, the movement of the sealing body 17 can be effectively suppressed.

[0040] The structure of the gasket 30 according to this embodiment will be described in more detail with further reference to Figures 4 and 5. Figure 4 is an enlarged view of part B in Figure 2, showing the state before crimping and fixing. Figure 5 shows another example of Figure 4. Below, the recess 34 of the opening edge of the outer can 15 before crimping will be described in detail.

[0041] As shown in Figure 4, before crimping and fixing, the gasket 30 has a recess 34 formed on the surface facing the side of the sealing body 17. The end 34x of the recess 34 on the opening side of the outer can 15 is formed offset toward the opening side of the outer can 15 compared to the surface (upper surface 17x) of the outer periphery 17a of the sealing body 17 that is on the opening side of the outer can 15. In other words, the end 34x of the recess 34 is located above the upper surface 17x of the outer periphery 17a (outer periphery 26b) of the sealing body 17.

[0042] Before caulking, the recess 34 is formed over the entire circumference on the surface of the gasket 30 facing the side surface of the sealing body 17 as described above. Further, the recess 34 has a shape that is recessed radially outward of the gasket 30 in a cross-sectional view and is an area that does not contact the sealing body 17. The recess 34 is preferably formed thinner than other areas of the gasket 30. That is, the thickness of the recess 34 is preferably formed to be thinner than the thickness of other areas. As a result, the recess 34 is likely to bend during caulking, suppressing the force applied in the radial direction of the sealing body 17 and suppressing the deformation of the sealing body 17.

[0043] The end portions 34x and 34y of the recess 34 before caulking may be formed parallel to the radial direction of the gasket 30 as illustrated in FIG. 4. Also, the length along the radial direction of the gasket 30 is such that the end portion 34x is formed larger than the end portion 34y. As will be described in detail later, this forms the claw portion 36.

[0044] Between the end portions 34x and 34y of the recess 34 before caulking, a side surface 34z formed parallel to the axial direction of the outer can 15 is provided as illustrated in FIG. 4. As described above, the recess 34 is formed thinner than other areas. As a result, when caulking, the side surface 34z bends to form so as to cover the upper edge of the sealing body 17. At this time, the side surface 34z may bend in an area that does not face the side surface of the sealing body 17.

[0045] The end portion 34y on the bottom side of the outer can 15 of the recess 34 is provided within the area facing the side surface of the sealing body 17 as described above. As a result, in the area facing the side surface of the sealing body 17, a movement suppressing portion 35 is formed with the recess 34 formed on the upper side and no recess 34 formed on the lower side.

[0046] The end portion 34y on the bottom side of the outer can 15 of the concave portion 34 is preferably formed so as to be shifted toward the opening side of the outer can 15 from the position of 50% of the thickness of the outer peripheral portion 17a of the sealing body 17. That is, the end portion 34y is preferably disposed in a region facing the upper half of the side surface of the sealing body 17. In other words, the movement suppressing portion 35 preferably has a length dimension of 50% or more of the thickness of the outer peripheral portion 17a of the sealing body 17. As a result, it is possible to more effectively prevent the sealing body 17 from shifting in the radial direction of the outer can 15.

[0047] The end portion 34x of the concave portion 34 before caulking the opening end portion of the outer can 15 is preferably shifted by 0.10 mm or more and 0.50 mm or less from the upper surface 17x. In other words, the end portion 34x preferably extends from the upper surface 17x by the above dimensions. As a result, since the force applied in the radial direction of the outer can 15 during caulking can be more effectively suppressed, the deformation of the sealing body 17 can be effectively suppressed. When the ratio of the concave portion 34 near the tip of the gasket 30 increases, the sealing performance near the concave portion 34 may deteriorate. Therefore, according to the concave portion 34 having the above dimensions, the deformation of the sealing body 17 can be suppressed while maintaining the sealing performance of the gasket 30.

[0048] As shown in FIG. 5, the gasket 30 has a claw portion 36 that protrudes radially inward of the gasket 30 to hold the sealing body 17 when the sealing body 17 is fitted. The claw portion 36 is provided on the radially inner surface of the gasket 30. The concave portion 34 before caulking may include an inclined portion 37 formed so as to gradually deepen in the radial direction of the gasket 30 as it goes downward (the bottom side of the outer can 15) from the claw portion 36. In this case, the end portion 34x of the concave portion 34 becomes the claw portion 36. Since the concave portion 34 has the inclined portion 37, the thickness portion of the upper annular portion 33 can be increased, so that the sealing performance of the upper annular portion 33 of the gasket 30 during caulking can be improved.

[0049] Hereinafter, a method for manufacturing the cylindrical battery 10 will be described.

[0050] The manufacturing method of the cylindrical battery 10 according to this embodiment includes, for example, the following steps: (1) a housing step of housing the electrode body 14, in which a positive electrode 11 and a negative electrode 12 are wound around a separator 13, into a bottomed cylindrical outer casing 15; (2) a recess forming step of forming a recess 34 around the entire circumference of the radially inner surface of a gasket 30 having a ring shape in plan view; (3) a sealing body placement step of fitting a sealing body 17 into the gasket 30; (4) a crimping step of bending the open end of the outer casing 15 radially inward to fix the gasket 30 and the sealing body 17 to the outer casing 15.

[0051] In the recess formation process, a recess 34 is formed on the surface of the sealing body 17 that faces the side surface in the sealing body placement process. The end 34x of the recess 34 on the opening side of the outer can 15 is formed so that it is offset toward the opening side of the outer can 15 than the opening side surface (upper surface 17x) of the outer periphery 17a of the sealing body 17. The end 34y of the recess 34 on the bottom side of the outer can 15 is formed so that it is located in the region between the bottom side surface (lower surface 17y) and the upper surface 17x of the outer periphery 17a of the sealing body 17. That is, the end 34y is provided in the region facing the side surface of the sealing body 17. As a result, the gasket 30 has a movement-restricting portion 35 in which a recess 34 is not formed below the region facing the side surface of the sealing body 17.

[0052] In the recess formation step, the recess 34 may be formed in such a way as to satisfy the structural characteristics of the gasket 30 described above. Alternatively, in the recess formation step, the position and dimensions of the recess 34 may be determined based on its relationship with other components such as the sealing body 17, and the recess 34 may then be formed.

[0053] In the recess formation process, it is preferable to form the recess 34 such that the bottom end 34y of the recess 34 on the outer can 15 side is shifted toward the opening of the outer can 15 from a position that is 50% of the thickness of the outer peripheral portion 17a of the sealing body 17. That is, it is preferable to form the recess 34 such that the end 34y is located in a region facing the upper half of the side surface of the sealing body 17. In other words, the recess 34 is formed such that the movement suppression portion 35 has a length dimension of 50% or more of the thickness of the outer peripheral portion 17a of the sealing body 17. As a result, it is possible to more effectively suppress the radial displacement of the sealing body 17 of the outer can 15 during crimping and fixing.

[0054] In the recess formation process, it is preferable to form the recess 34 such that the end portion 34x of the recess 34 is offset from the upper surface 17x by 0.10 mm to 0.50 mm. In other words, it is preferable that the end portion 34x extends from the upper surface 17x by the above dimensions. As a result, the force applied to the outer can 15 in the radial direction during crimping can be suppressed more effectively, and thus deformation of the sealing body 17 can be effectively suppressed.

[0055] In the recess formation process, it is preferable to form the recess 34 such that its radial depth is 0.01 mm or more and 50% or less of the thickness of the gasket 30. In other words, it is preferable to form the recess 34 such that the radial dimension of the gasket 30 is within the above range. As a result, the radial force applied to the sealing body 17 during crimping can be suppressed, and deformation of the sealing body 17 can be effectively suppressed.

[0056] In the recess formation process, an inclined portion 37 may be formed such that it gradually deepens in the radial direction of the gasket 30 as it moves downward from the claw portion 36 (towards the bottom of the outer can 15). In this case, the end portion 34x of the recess 34 becomes the claw portion 36. Since the recess 34 has an inclined portion 37, the thickness of the upper annular portion 33 can be increased, thereby improving the sealing performance of the upper annular portion 33 of the gasket 30 when it is crimped and fixed.

[0057] The process includes a crimping step in which the sealing body 17 and gasket 30 are placed in the opening of the outer can 15, the opening edge of the outer can 15 is folded radially inward, and the assembly is crimped in place. By crimping, a cylindrical battery 10 can be manufactured. At this time, the presence of a recess 34 in the gasket 30 suppresses the radial force applied to the sealing body 17 during crimping, thereby suppressing deformation of the sealing body 17. Furthermore, the presence of a movement-restricting portion 35 on the lower side of the region facing the side surface of the sealing body 17, where the recess 34 is not formed, suppresses the movement of the sealing body 17 and prevents deterioration of sealing performance.

[0058] This disclosure is further illustrated by the following embodiments. Configuration 1: A cylindrical battery comprising an electrode body having a positive electrode, a negative electrode, and a separator, formed by winding the positive electrode and the negative electrode via the separator; a bottomed cylindrical outer casing housing the electrode body; a sealing body that closes the opening of the outer casing; and a gasket having a ring shape in plan view, disposed between the outer casing and the sealing body, wherein a recess is formed around the entire circumference of the surface of the gasket facing the side surface of the sealing body, the recess is provided to cover the edge of the sealing body on the opening side of the outer casing, and a movement-restricting portion is formed on the bottom side of the outer casing in the region of the gasket facing the side surface of the sealing body, wherein the recess is not formed. Configuration 2: The cylindrical battery according to Configuration 1, wherein the bottom end of the recess on the outer casing is offset toward the opening side of the outer casing from a position 50% of the thickness of the outer circumference of the sealing body. Configuration 3: The cylindrical battery according to Configuration 1 or 2, wherein the radial depth of the recess is 0.01 mm or more and 50% or less of the thickness of the gasket. Configuration 4: The cylindrical battery according to any one of Configurations 1 to 3, wherein the end of the recess on the opening side of the recess before the opening end of the outer casing is crimped is on the outer circumference of the sealing body and is offset by 0.10 mm or more and 0.50 mm or less from the surface on the opening side. Configuration 5: The cylindrical battery according to any one of Configurations 1 to 4, wherein the gasket has a claw portion on its radial inner surface that protrudes radially inward to hold the sealing body when the sealing body is fitted, and the recess before the opening end of the outer casing is crimped includes an inclined portion formed such that it gradually deepens radially from the claw portion toward the bottom side of the outer casing.Configuration 6: A method for manufacturing a cylindrical battery, comprising: a housing step of housing an electrode body, in which a positive electrode and a negative electrode are wound via a separator, into a bottomed cylindrical outer can; a recess forming step of forming a recess around the entire circumference of the radially inner surface of a gasket having a ring shape in plan view; a sealing body placement step of fitting a sealing body into the gasket; a crimping step of bending the open end of the outer can radially inward to fix the gasket and the sealing body to the outer can; and a crimping step of bending the open end of the outer can radially inward to fix the gasket and the sealing body to the outer can, wherein in the recess forming step, the end of the recess on the opening side of the outer can is formed to be offset toward the opening side of the outer can than the opening side surface of the outer circumference of the sealing body, and the end of the recess on the bottom side of the outer can is formed to be located in the region between the bottom side surface of the outer circumference of the sealing body and the opening side surface.

[0059] 10 Cylindrical battery 11 Positive electrode 12 Negative electrode 13 Separator 14 Electrode body 15 Outer casing 16 Grooved section 17 Sealing body 17x, 26x Top surface 17y, 26y Bottom surface 18 Crimped section 20 Positive electrode lead 21 Negative electrode lead 22, 23 Insulating plate 24 Internal terminal plate 24a Thin-walled section 25 Annular insulating plate 26 Sealing plate 26a Center section 26b Outer periphery section 26c Inclined section 26d Annular end section 26x Top surface 26y Bottom surface 27 Annular groove 30 Gasket 31 Lower annular section 32 Side section 33 Upper annular section 34 Recess 34x, 34y End section 34z Side section 35 Movement suppression section 36 Claw section 37 Slanted part P Tip

Claims

1. A cylindrical battery comprising: an electrode body having a positive electrode, a negative electrode, and a separator, formed by winding the positive electrode and the negative electrode with the separator in between; a bottomed cylindrical outer can housing the electrode body; a sealing body closing the opening of the outer can; and a gasket having a ring shape in plan view, disposed between the outer can and the sealing body, wherein a recess is formed around the entire circumference of the surface of the gasket facing the side surface of the sealing body, the recess is provided to cover the edge of the sealing body on the opening side of the outer can, and a movement-restricting portion is formed on the bottom side of the outer can in the region of the gasket facing the side surface of the sealing body, where the recess is not formed.

2. The cylindrical battery according to claim 1, wherein the bottom end of the recess of the outer casing is offset toward the opening of the outer casing from a position that is 50% of the thickness of the outer circumference of the sealing body.

3. The cylindrical battery according to claim 1, wherein the radial depth of the recess is 0.01 mm or more and 50% or less of the thickness of the gasket.

4. The cylindrical battery according to claim 1, wherein the end of the recess on the opening side of the outer can before crimping the opening end of the outer can is offset by 0.10 mm or more and 0.50 mm or less from the outer circumference of the sealing body and the surface on the opening side.

5. The cylindrical battery according to any one of claims 1 to 4, wherein the gasket has a claw portion on its radially inner surface that protrudes radially inward to hold the sealing body when the sealing body is fitted, and the recess before the opening end of the outer can is crimped includes an inclined portion formed such that it gradually deepens radially of the gasket from the claw portion toward the bottom of the outer can.

6. A method for manufacturing a cylindrical battery, comprising: a housing step of housing an electrode body, in which a positive electrode and a negative electrode are wound with a separator between them, in a bottomed cylindrical outer can; a recess forming step of forming a recess around the entire circumference of the radially inner surface of a gasket having a ring shape in plan view; a sealing body placement step of fitting a sealing body into the gasket; and a crimping step of bending the open end of the outer can radially inward to fix the gasket and the sealing body to the outer can, wherein in the recess forming step, the end of the recess on the opening side of the outer can is formed to be offset toward the opening side of the outer can than the opening side surface of the outer circumference of the sealing body, and the end of the recess on the bottom side of the outer can is formed to be located in the region between the bottom side surface of the outer circumference of the sealing body and the opening side surface.

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