Cylindrical battery and method for manufacturing cylindrical battery

Abstract

A cylindrical battery 10 includes: an electrode body that is formed by wrapping a positive electrode and a negative electrode with a separator interposed therebetween; a bottomed cylindrical outer can 15 that accommodates the electrode body; a sealing body 17 that closes an opening portion 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 a plan view. A grooved portion 16 that protrudes radially inward and that is formed over the circumferential direction of the outer can 15 is formed in a side surface of the outer can 15. The gasket 30 has a reinforcing portion 34 that protrudes toward the bottom of the outer can 15 and that includes a shape conforming to the shape of the grooved portion 16, and the reinforcing portion 34 is provided with a lead passing portion 35 that is aligned in the radial direction of the gasket 30 with a positive electrode lead 20 extending from the electrode body 14.

Description

Cylindrical Battery and Method for Manufacturing Cylindrical Battery

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

[0002] A cylindrical battery generally includes an electrode body, an outer can that houses the electrode body, and a sealing body that closes the 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 Unexamined Patent Application Publication No. 2013-93294

[0004] In order to seal the inside of the outer can, the cylindrical battery fixes the sealing body 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, it is necessary to apply a large load to the end of the sealing plate. However, at that time, if the rigidity of the sealing plate is low, the sealing plate will deform, resulting in a decrease in battery performance such as a decrease in airtightness and a fluctuation in the operating pressure of a current interruption mechanism or the like.

[0005] In such a background, a convex portion protruding toward the bottom of the outer can is formed on the gasket, and the outer can supports the sealing body via the convex portion by contacting a part of the outer can, thereby suppressing deformation of the sealing body. However, in the assembly of the cylindrical battery, in order to suppress the adhesion of the electrolytic solution to the gasket during liquid injection, in some cases, the electrode lead extending from the electrode and the sealing body are welded in a state where the gasket and the sealing body are assembled. In this case, the convex portion of the gasket interferes with the electrode lead, deteriorating the weldability between the sealing body and the electrode lead. Note that the cylindrical battery described in Patent Document 1 cannot solve such a problem either.

[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 for closing 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 the side surface of the outer casing has grooves formed over the circumferential direction of the outer casing and protruding radially inward, and the gasket has reinforcing portions that protrude toward the bottom of the outer casing and include a shape that conforms to the shape of the grooves, and the reinforcing portions are provided with lead passages that extend from the electrode body and are aligned radially with the gasket.

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

[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 section A in Figure 1. This diagram shows the respective configurations of the sealing body and the positive electrode lead during welding. This is a cross-sectional view taken along line B-B in Figure 3.

[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 gasket 30, which has a ring shape in plan view, 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. As will be described in more detail later, in the cylindrical battery 10 according to this embodiment, the sealing body 17 is welded to the ring-shaped gasket 30 with the axial direction of the sealing body 17 and gasket 30 perpendicular to the axial direction of the electrode body 14, with the sealing body 17 fitted into the ring-shaped gasket 30 in plan view.

[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 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] The structure of the gasket 30 according to this embodiment will be described in detail with further reference to Figures 3 and 4. Figure 3 is a diagram showing the respective configurations of the sealing body 17 and the positive electrode lead 20 during welding. Figure 4 is a cross-sectional view taken along line B-B in Figure 3. Note that in Figure 3, the sealing body 17 is shown in a simplified manner for clarity.

[0031] 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.

[0032] The gasket 30 has a reinforcing portion 34 that protrudes toward the bottom of the outer can 15 and includes a shape that conforms to the shape of the grooved portion 16. More specifically, the gasket 30 has a reinforcing portion 34 at its radially inward end, which protrudes toward the bottom of the outer can 15 toward the lower surface of the lower annular portion 31. The reinforcing portion 34 is provided with a lead passage portion 35 that is aligned radially with the positive electrode lead 20 extending from the electrode body 14 and the gasket 30. The lead passage portion 35 is through which the positive electrode lead 20 passes when the sealing body 17 and the positive electrode lead 20 are welded together. The gasket 30 supports the outer circumference of the sealing body 17 on the upper surface of the lower annular portion 31 by the reinforcing portion 34 contacting the grooved portion 16.

[0033] As described above, the reinforcing portion 34 includes a portion that conforms to the shape of the grooved portion 16 of the outer can 15. More specifically, it is preferable that the reinforcing portion 34 includes a shape that conforms to the shape of the upper half of the grooved portion 16. For example, if the grooved portion 16 has a U-shaped cross-section as shown in Figure 2, it is preferable that the reinforcing portion 34 has a curved surface that conforms to the U-shape. By including a shape that matches the inner surface of the grooved portion 16, the grooved portion 16 receives forces acting on the outer can 15 in the axial and radial directions via the reinforcing portion 34, effectively suppressing deformation of the sealing body 17, and thus suppressing a decrease in battery performance.

[0034] As shown in Figure 2, it is preferable that the reinforcing portion 34 extends radially inward from the tip P of the grooved portion 16 to the outer casing 15. In other words, it is preferable that the lower annular portion 31 extends radially inward from the tip P of the grooved portion 16 to the outer casing 15. By extending the lower annular portion 31 (reinforcing portion 34) of the gasket 30 radially inward from the tip P of the grooved portion 16 to the outer casing 15, the area over which the grooved portion 16 supports the sealing body 17 via the gasket 30 increases, and deformation of the sealing body 17 can be effectively suppressed. As a result, the airtightness of the cylindrical battery 10 can be improved, and safety can be enhanced. The radial length of the reinforcing portion 34 (lower annular portion 31) on the outer casing 15 is not particularly limited as long as the above conditions are met, but it is preferable that it be a length that does not impair the function of other components. For example, it is preferable that it be a length that does not come into contact with the positive electrode lead 20.

[0035] Preferably, the bottom surface of the reinforcing portion 34 on the outer can 15 is located at substantially the same axial height as the radially inward tip P of the grooved portion 16. That is, it is preferable that the reinforcing portion 34 is formed to cover the upper half of the grooved portion 16. In this case, the grooved portion 16 can withstand the force applied from above the outer can 15 to the maximum extent through the reinforcing portion 34 of the gasket 30, thereby effectively suppressing deformation of the sealing body 17.

[0036] Preferably, the reinforcing portion 34 is formed around the entire circumference of the gasket 30, except for the lead passage portion 35. That is, the reinforcing portion 34 is formed in an arc shape when viewed from the bottom. The reinforcing portion 34 is formed in a C shape, for example, as shown in Figure 3. In this case, the reinforcing portion 34 is formed to the maximum extent, and the sealing body 17 can be supported more effectively. As a result, deformation of the sealing body 17 is suppressed, a decrease in battery performance is suppressed, and a decrease in weldability between the sealing body 17 and the positive electrode lead 20 can be suppressed by providing the lead passage portion 35.

[0037] As described above, the reinforcing portion 34 is provided with a lead passage portion 35 that is aligned radially with the positive electrode lead 20 extending from the electrode body 14 and the gasket 30 after the outer can 15 is sealed. More specifically, the lead passage portion 35 is provided at a position that overlaps with a hypothetical line, assuming a hypothetical line at the center of the positive electrode lead 20 in the width direction. The lead passage portion 35 is the lower annular portion 31, the part where the reinforcing portion 34 is not formed. More specifically, the lead passage portion 35 includes a region at the radially inner end of the gasket 30 where the reinforcing portion 34 is not formed. The lead passage portion 35 is, for example, a region formed over the entire width of the gasket 30. The lead passage portion 35 may have the same thickness as the lower annular portion 31.

[0038] The lead passage portion 35 is a region provided in a part of the reinforcing portion 34 that follows the shape of the grooved portion 16, and is grooved when viewed from the reinforcing portion 34. That is, the lead passage portion 35 is formed as a recess when viewed from the reinforcing portion 34. Side surfaces 35a and 35b are formed at both ends of the lead passage portion 35. The side surfaces 35a and 35b of the lead passage portion 35 form both ends of the lead passage portion 35 and also form both ends of the reinforcing portion 34.

[0039] In this embodiment, the sides 35a and 35b of the lead passage portion 35 are formed to be parallel to the axial direction of the outer can 15 in the state before sealing as shown in Figure 3. Furthermore, it is preferable that the sides 35a and 35b of the lead passage portion 35 are formed parallel to the center line passing through the widthwise center of the positive electrode lead 20. This makes it easier to avoid contact between the reinforcing portion 34 and the positive electrode lead 20, and suppresses deterioration of weldability.

[0040] Figure 3 illustrates the center point O of the sealing body 17 and the innermost radial points of the gasket 30 on the sides 35a and 35b. It also shows imaginary lines connecting the center point O and the innermost radial point of side 35a, and imaginary lines connecting the center point O and the innermost radial point of side 35b. Furthermore, the central angle θ formed by these imaginary lines is indicated. Preferably, the lead passage portion 35 is formed such that the distance between the innermost radial points of the gasket 30 on sides 35a and 35b is greater than or equal to the width of the positive electrode lead 20, and the central angle θ formed by the three points of the sealing body 17, the center point O, and the innermost radial points of the gasket 30 on sides 35a and 35b is 90° or less.

[0041] The straight-line distance L between the ends of the reinforcing portions 34 located at both ends of the lead passage portion 35 is preferably between 100% and 130% of the widthwise length of the positive electrode lead 20. Furthermore, the lead passage portion 35 is more preferably between 100% and 120% of the widthwise length of the positive electrode lead 20, and particularly preferably between 100% and 110%. Specifically, the length of the straight line drawn connecting each end of the arc-shaped reinforcing portion 34 with a straight line parallel to the radial direction of the gasket 30 has the above dimensions. In other words, the length between the sides 35a and 35b of the lead passage portion 35 has the above dimensions. By having the above dimensions for the lead passage portion 35, it is possible to effectively suppress the deterioration of battery performance due to deformation of the sealing body 17 and the deterioration of weldability between the sealing body 17 and the positive electrode lead 20.

[0042] As described above, the lead passage portion 35 is provided at a position aligned radially with the positive electrode lead 20 extending from the electrode body 14 and the gasket 30. In the state before sealing as illustrated in Figure 3, it is preferable that the lead passage portion 35 is formed such that, when viewed from the thickness direction of the gasket, the center of the straight line between the ends of the reinforcing portions 34 located at both ends coincides with the center line in the width direction of the positive electrode lead 20.

[0043] The lead passing portion 35 is preferably located on the opening side of the outer can 15 rather than on the surface of the sealing body 17 facing the electrode body 14. That is, the lead passing portion 35 is formed such that the lower surface of the lead passing portion 35 is located above the lower surface of the sealing body 17. In this case, the lower surface of the lead passing portion 35 is preferably located within a region 1.0 mm upward from the lower surface of the sealing body 17. Since the lower surface of the lead passing portion 35 is located above the lower surface of the sealing body 17, it is possible to prevent the lead passing portion 35 from interfering with the positive electrode lead 20 during welding of the sealing body 17 and the positive electrode lead 20, and thus it is possible to suppress deterioration of the weldability between the sealing body 17 and the positive electrode lead 20. Note that the lower surface of the lead passing portion 35 may be located substantially at the same height as the lower surface of the sealing body 17. Here, being located substantially at the same height includes the case where the lower surface of the lead passing portion 35 extends downward by 0.5 mm or less from the lower surface of the sealing body 17.

[0044] The lead passing portion 35 is provided at a position where the positive electrode lead 20 can pass through during welding of the sealing body 17 and the positive electrode lead 20. Specifically, as shown in FIGS. 3 and 4, the lead passing portion 35 is provided at a position overlapping the positive electrode lead 20 in the axial direction of the gasket 30 when the sealing body 17 and the positive electrode lead 20 are welded in a state where the axial direction of the sealing body 17 and the gasket 30 is orthogonal to the axial direction of the electrode body 14. The lead passing portion 35 is provided so as not to interfere with the positive electrode lead 20, as shown in FIG. 4.

[0045] The lead passing portion 35 is formed so as to overlap a straight line passing through the center point O of the sealing body 17 when viewed from the thickness direction of the sealing body 17. In the present embodiment, the center line passing through the centers of the side surfaces 35a and 35b of the lead passing portion 35 is formed so as to overlap a straight line passing through the center point O of the sealing body 17.

[0046] As described above, according to the cylindrical battery 10 having the above configuration, it is possible to suppress deterioration of the battery performance due to deformation of the sealing body 17 and to suppress deterioration of the weldability between the sealing body 17 and the positive electrode lead 20.

[0047] In the above embodiment, the case where there is one positive electrode lead 20 has been described. However, the positive electrode lead 20 extending from the electrode body 14 is not limited to one. For example, a plurality of positive electrode leads 20 may extend so as to overlap in the radial direction of the electrode body 14, and they may be welded to the sealing body 17. Alternatively, a master lead to which a plurality of positive electrode leads 20 are connected may be welded to the sealing body 17.

[0048] Hereinafter, a method for manufacturing the cylindrical battery 10 will be described. In the method for manufacturing the cylindrical battery 10 according to the present embodiment, welding of the sealing body 17 and the lead extending from the electrode body 14 is performed in a state where the sealing body 17 is fitted into the ring-shaped gasket 30.

[0049] The method for manufacturing the cylindrical battery 10 according to the present embodiment includes, for example, the following steps. (1) A housing step of housing an electrode body 14 obtained by winding a positive electrode 11 and a negative electrode 12 with a separator 13 in a bottomed cylindrical outer can 15. (2) An assembly step of fitting the sealing body 17 into a gasket 30 including a reinforcing portion 34 protruding on one side in the axial direction and a lead passage portion 35 provided in the reinforcing portion 34, and arranging the sealing body 17 so as to be located inside the gasket 30 in the radial direction. (3) A welding step of passing a positive electrode lead 20 connected to the positive electrode 11 of the electrode body 14 through the lead passage portion 35 and welding it to the sealing body 17 in a state where the axial direction of the electrode body 14 is orthogonal to the axial directions of the sealing body 17 and the gasket 30.

[0050] Specifically, in the assembly step, the sealing body 17 having a disc shape in plan view is fitted into the gasket 30 having a ring shape in plan view. Here, since the assembly step is performed before caulking and fixing, the sealing body 17 is assembled by the claw portions 36 provided on the gasket 30 so as not to come off. Further, when the sealing body 17 is composed of a plurality of members, the plurality of members are assembled and then fitted into the gasket 30.

[0051] In the welding process, as shown in Figures 3 and 4, the electrode body 14 is positioned so that its axial direction is perpendicular to the axial direction of the sealing body 17 and the gasket 30. At this time, the gasket 30 is positioned so that the positive electrode lead 20 does not overlap with the reinforcing portion 34 of the gasket 30. In other words, the gasket 30 is positioned so that the positive electrode lead 20 passes through the lead passage portion 35 of the gasket 30. After that, the positive electrode lead 20 is welded to the sealing body 17 and the electrolyte is poured into the outer casing 15. By positioning the components so that the axial direction of the electrode body 14 is perpendicular to the axial direction of the sealing body 17 and the gasket 30, adhesion of the electrolyte to the gasket 30 is suppressed. If the electrolyte adheres to the gasket 30, it will seep out from the gasket 30 after the battery is assembled, causing rust and staining of the outer casing 15, so the above welding process can suppress the occurrence of these problems.

[0052] In the welding process, the gasket 30 is positioned so that the positive electrode lead 20 passes through the lead passage portion 35 of the gasket 30, as described above. As shown in Figure 4, since the lead passage portion 35 is formed in the gasket 30, the reinforcing portion 34 does not interfere with the positive electrode lead 20, and deterioration of the weldability between the positive electrode lead 20 and the sealing body 17 can be suppressed.

[0053] The process after the welding step includes a crimping step in which the sealing body 17 and gasket 30 are placed in the opening of the outer can 15, and the opening edge of the outer can 15 is bent radially inward and crimped in place. By crimping in place, a cylindrical battery 10 can be manufactured. At this time, the gasket 30 is provided with a reinforcing portion 34, which suppresses deformation of the sealing body 17 during crimping. Specifically, the reinforcing portion 34 abuts against the grooved portion 16 of the outer can 15, so that the grooved portion 16 can receive the upward force applied to the sealing body 17 via the reinforcing portion 34, thereby suppressing deformation of the sealing body 17. During the crimping step, the positive electrode lead 20 is bent and stored inside the outer can 15, for example, as shown in Figure 2.

[0054] In addition to the above steps, a reinforcement forming step may be included before the assembly step. In the reinforcement forming step, a reinforcement portion 34 protruding to one side in the axial direction and a lead passage portion 35 provided on the reinforcement portion 34 are formed on the gasket 30. In the reinforcement forming step, the reinforcement portion 34 and the lead passage portion 35 may be formed in such a way as to satisfy the structural characteristics of the gasket 30 described above.

[0055] In the reinforcement forming step, the reinforcement portion 34 in the gasket 30 may be formed based on the shape of the outer can 15. In the reinforcement forming step, the reinforcement portion 34 may be formed to include a shape that conforms to the shape of the grooved portion 16 of the outer can 15. More specifically, in the reinforcement forming step, the reinforcement portion 34 is formed to include a shape that conforms to the shape of the upper half of the grooved portion 16.

[0056] In the reinforcement formation process, it is preferable that the reinforcement portion 34 is formed so that it extends radially inward from the tip P of the grooved portion 16 to the outer can 15. In other words, it is preferable that the lower annular portion 31 on which the reinforcement portion 34 is formed extends radially inward from the tip P of the grooved portion 16 to the outer can 15.

[0057] In the reinforcing portion formation process, it is preferable that the bottom surface of the reinforcing portion 34 on the outer can 15 is positioned at substantially the same axial height as the radially inward tip P of the grooved portion 16. That is, it is preferable that the reinforcing portion 34 is formed to cover the upper half of the grooved portion 16.

[0058] The reinforcement portion formation process is the process of forming the reinforcement portion 34 and the lead passage portion 35, as described above. The lead passage portion 35 is provided in the reinforcement portion 34. In other words, forming the reinforcement portion 34 means forming the lead passage portion 35. The formation of the lead passage portion 35 in the reinforcement portion formation process will be described below. Note that the lead passage portion 35 may be formed based on the dimensions of the sealing body 17.

[0059] In the reinforcement portion formation process, it is preferable that the straight-line distance between the ends of the reinforcement portions 34 located at both ends of the lead passage portion 35 is formed to be more than 100% but 130% or less of the widthwise length of the positive electrode lead 20. More preferably, the length is more than 100% but 120% or less, and particularly preferably, the length of the reinforcement portions 34 and the lead passage portion 35 is formed to be more than 100% but 110% or less.

[0060] In the reinforcement portion formation process, it is preferable to form the lead passage portion 35 so that it does not protrude from the surface of the sealing body 17 to which the positive electrode lead 20 is welded. That is, the lead passage portion 35 may be formed based on the dimensions of the sealing body 17. It is preferable that the thickness of the lead passage portion 35 be formed to be less than or equal to the length from the surface that abuts the grooved portion 16 on the outer circumference of the sealing body 17 to the surface that abuts the positive electrode lead 20 of the sealing body 17.

[0061] 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 closing 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 groove is formed on the side surface of the outer casing, extending circumferentially over the outer casing and protruding radially inward, the gasket having a reinforcing portion that protrudes toward the bottom of the outer casing and includes a shape conforming to the shape of the groove, and the reinforcing portion is provided with lead passages extending from the electrode body and lead passages aligned radially with the sealing body. Configuration 2: The cylindrical battery according to Configuration 1, wherein the reinforcing portion extends radially inward beyond the radially inward end of the groove on the outer casing. Configuration 3: The cylindrical battery according to Configuration 1 or 2, wherein the bottom surface of the reinforcing portion of the outer casing is located at the same axial height of the outer casing as the radially inward tip of the grooved portion of the outer casing. Configuration 4: The cylindrical battery according to any one of Configurations 1 to 3, wherein the reinforcing portion is formed around the entire circumference of the radially inward end of the gasket, excluding the lead passage portion. Configuration 5: The cylindrical battery according to any one of Configurations 1 to 4, wherein the straight-line distance between the ends of the reinforcing portions located at both ends of the lead passage portion is greater than 100% but less than or equal to 130% of the widthwise length of the lead in the radial direction of the outer casing. Configuration 6: The cylindrical battery according to any one of Configurations 1 to 5, wherein the lead passage portion is located at the same height as the surface of the sealing body facing the electrode body, or is located on the opening side of the outer casing more than the surface of the sealing body facing the electrode body.Configuration 7: A method for manufacturing a cylindrical battery, comprising welding leads extending from an electrode body to a sealing body while the sealing body is fitted into a ring-shaped gasket, the method comprising: a housing step of housing the electrode body, in which a positive electrode and a negative electrode are wound via a separator, into a bottomed cylindrical outer casing; an assembly step of fitting the sealing body into the gasket, which includes a reinforcing portion protruding to one side in the axial direction and a lead passage portion provided in the reinforcing portion, and arranging the sealing body so that it is located radially inside the gasket; and a welding step of welding the leads to the sealing body while the leads extending toward one side in the axial direction of the electrode body and the lead passage portion are arranged so that they overlap in the thickness direction of the gasket.

[0062] 10 Cylindrical battery 11 Positive electrode 12 Negative electrode 13 Separator 14 Electrode body 15 Outer casing 16 Grooved section 17 Sealing section 18 Crimped section 20 Positive lead 21 Negative lead 22, 23 Insulating plate 24 Internal terminal plate 24a Thin section 25 Annular insulating plate 26 Sealing plate 26a Center section 26b Outer periphery section 26c Inclined section 26d Annular end section 27 Annular groove 30 Gasket 31 Lower annular section 32 Side section 33 Upper annular section 34 Reinforcement section 35 Lead passage section 36 Claw section 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 casing for housing the electrode body; a sealing body for closing 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 the side surface of the outer casing has grooves formed over the circumferential direction of the outer casing and protruding radially inward, the gasket having a reinforcing portion that protrudes toward the bottom of the outer casing and includes a shape that conforms to the shape of the groove, and the reinforcing portion is provided with lead passages that extend from the electrode body and are aligned radially with the gasket.

2. The cylindrical battery according to claim 1, wherein the reinforcing portion extends radially inward from the radially inward tip of the outer casing of the grooved portion.

3. The cylindrical battery according to claim 1, wherein the bottom surface of the outer casing of the reinforcing portion is located at the same axial height as the radially inward tip of the outer casing of the grooved portion.

4. The cylindrical battery according to claim 1, wherein the reinforcing portion is formed around the entire circumference of the radially inner end of the gasket, excluding the lead passage portion.

5. The cylindrical battery according to claim 1, wherein the straight-line distance between the ends of the reinforcing portions located at both ends of the lead passage portion is greater than 100% but less than or equal to 130% of the widthwise length of the lead in the radial direction of the outer casing.

6. The cylindrical battery according to any one of claims 1 to 5, wherein the lead passage portion is at the same height as the surface of the sealing body facing the electrode body, or is located on the opening side of the outer casing can than the surface of the sealing body facing the electrode body.

7. A method for manufacturing a cylindrical battery, comprising: a housing step of housing the electrode body, in which a sealing body is fitted into a ring-shaped gasket, and leads extending from the sealing body and leads extending from the electrode body, the sealing body being fitted into a gasket including a reinforcing portion protruding to one side in the axial direction and a lead passage portion provided in the reinforcing portion, and arranging the sealing body so that it is located radially inward of the gasket; and a welding step of welding the leads to the sealing body in which the leads extending toward one side in the axial direction of the electrode body and the lead passage portion are arranged so that they overlap in the thickness direction of the gasket.

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