Cylindrical battery

Abstract

This battery (10) comprises an integrated cap (30) including: an annular covering part (81) covering at least a portion of the outer surface of a shoulder part (29) of an outer can (16); a cylindrical part (82) extending substantially in the axial direction; and a groove arrangement part (83) disposed in an annular groove (80) defined by a groove part (22). A surface (67) on the bottom side in the axial direction of the groove part (22) of the outer can (16) has a recess (70) that opens toward a sealing body (17) in the axial direction. The groove arrangement part (83) includes an accommodation part (71) accommodated in the recess (70).

Description

Cylindrical battery

[0001] The present disclosure relates to cylindrical batteries.

[0002] A conventional cylindrical battery is described in Patent Document 1. This cylindrical battery includes an electrode assembly, a bottomed cylindrical outer can that houses the electrode assembly, a sealing body that closes the opening of the outer can, and a cylindrical reinforcing body. The cylindrical portion of the outer can has a grooved portion and an annular shoulder portion. The grooved portion is formed by recessing a portion of the cylindrical portion radially inward. The shoulder portion is formed when the end of the cylindrical portion on the opening side is bent inward and crimped to the peripheral edge of the sealing body, and extends radially inward. The reinforcing body is arranged to cover the outer surface of the outer can from the shoulder portion to the portion beyond the grooved portion.

[0003] Japanese Patent Application Publication No. 9-306443

[0004] If the energy density of a battery is increased, the internal pressure will increase if the battery generates abnormal heat due to an internal short circuit, etc., which may cause the sealing body to pop out. In that case, the opening of the outer can will be exposed to the outside, and materials inside the battery may be scattered to the outside, potentially affecting devices around the battery.

[0005] The technology described in Patent Document 1 aims to solve the problem of reduced battery sealing when thin-walled cans or aluminum cans, which have weaker crimping strength than steel cans, are used as battery containers. In the cylindrical battery described in Patent Document 1, the reinforcing body has a portion that fits into the annular groove defined by the grooved portion. However, the force that engages the reinforcing body with the grooved portion is weak, leaving room for improvement in preventing the sealing body from popping out during abnormal battery heat generation. Therefore, the object of the present disclosure is to provide a cylindrical battery that can effectively prevent the sealing body from popping out during abnormal battery heat generation.

[0006] In order to solve the above problems, the cylindrical battery according to the present disclosure comprises: an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; a cylindrical outer can with a bottom that houses the electrode assembly and has a shoulder extending radially inward at one axial end and a tubular portion including a grooved portion recessed radially inward around the entire circumferential circumference, and a bottom that closes the opening on the other axial side of the tubular portion; a sealing body that is crimped and fixed to the opening of the outer can via a gasket; and an integral cap that includes an annular covering portion that covers at least a portion of the outer surface of the shoulder, a cylindrical portion that extends substantially in the axial direction, and a grooved portion that is disposed in the annular groove defined by the grooved portion, wherein the axial bottom surface of the grooved portion has a recess that opens toward the sealing body in the axial direction, and the grooved portion includes a housing portion housed in the recess.

[0007] The cylindrical battery according to the present disclosure can effectively prevent the sealing body from popping out in the event of abnormal heat generation.

[0008] 1 is an axial cross-sectional view of a cylindrical battery according to an embodiment of the present disclosure; FIG. 2 is a perspective view showing a portion of an electrode body and a positive electrode lead; FIG. 3 is an enlarged cross-sectional view of the periphery of a grooved portion in FIG. 1; FIG. 4 is an enlarged cross-sectional view corresponding to FIG. 3 when an upward force is applied to the cap from a shoulder portion when abnormal heat generation occurs in the battery;

[0009] Hereinafter, an embodiment of a cylindrical battery according to the present disclosure will be described in detail with reference to the drawings. The cylindrical battery according to the present 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. Hereinafter, a non-aqueous electrolyte secondary battery (lithium ion battery) using a non-aqueous electrolyte will be exemplified as a cylindrical battery 10 according to one embodiment, but the cylindrical battery according to the present disclosure is not limited thereto.

[0010] When multiple embodiments and variations are included below, it is anticipated from the beginning that new embodiments can be constructed by appropriately combining their characteristic features. In the following embodiments, the same components are designated by the same reference numerals in the drawings, and redundant explanations are omitted. The drawings include schematic diagrams, and the dimensional ratios of the length, width, height, etc. of each component between different drawings do not necessarily match. In this specification, the side of the sealing body 17 in the axial direction (height direction) of the cylindrical battery 10 is referred to as "upper," and the side of the bottom 68 of the outer can 16 in the axial direction is referred to as "lower." Among the components described below, components not recited in the independent claims representing the highest concepts are optional and not required.

[0011] Fig. 1 is an axial cross-sectional view of a cylindrical battery 10 according to one embodiment of the present disclosure. As shown in Fig. 1, the cylindrical battery (hereinafter simply referred to as battery) 10 includes a wound electrode assembly 14, a non-aqueous electrolyte (not shown), a cylindrical outer can 16 with a bottom that houses the electrode assembly 14 and the non-aqueous electrolyte, a sealing body 17 that is crimped and fixed to the opening of the outer can 16 via a gasket 28, and an annular cap 30 that is disposed on the outside of the outer can 16. The outer can 16 and the cap 30 are made of a metal material.

[0012] The non-aqueous electrolyte has ion conductivity (e.g., lithium ion conductivity). The non-aqueous electrolyte may be a liquid electrolyte (electrolytic solution) or a solid electrolyte. The liquid electrolyte (electrolytic solution) includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous solvent include esters, ethers, nitriles, amides, and mixed solvents of two or more of these. Examples of the non-aqueous solvent include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents of these. The non-aqueous solvent may contain a halogen-substituted compound (e.g., fluoroethylene carbonate) in which at least a portion of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine. The electrolyte salt may include, for example, LiPF ６ Lithium salts such as

[0013] Examples of the solid electrolyte include solid or gel polymer electrolytes and inorganic solid electrolytes. 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. Examples of the matrix polymer include a polymer material that absorbs the non-aqueous solvent and gels. Examples of the polymer material include fluororesin, acrylic resin, and polyether resin. Examples of the inorganic solid electrolyte include materials known in all-solid-state lithium ion secondary batteries (e.g., oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.).

[0014] Fig. 2 is a perspective view showing a portion of the electrode assembly 14 and the positive electrode lead 20. As shown in Fig. 2, the electrode assembly 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 with the separator 13 interposed therebetween. A plurality of positive electrode leads 20 are joined to the positive electrode 11 at intervals from one another in the longitudinal direction of the positive electrode 11 for electrical connection; for example, as shown in Fig. 2, eight positive electrode leads 20 are joined to the positive electrode at intervals from one another in the longitudinal direction. It is preferable that a plurality of positive electrode leads 20 be joined to the positive electrode at approximately equal intervals from one another in the longitudinal direction of the positive electrode.

[0015] The negative electrode 12 is formed to have dimensions slightly larger than the positive electrode 11 in order to prevent lithium precipitation. The negative electrode 12 is formed to be longer in the longitudinal direction and width direction (short direction) than the positive electrode 11. Two separators 13 are formed to have dimensions slightly larger than the positive electrode 11 and are arranged to sandwich the positive electrode 11. The separator 13 protrudes upward beyond the positive electrode 11 and the negative electrode 12, and the negative electrode 12 protrudes downward beyond the positive electrode 11 and the separator 13.

[0016] The negative electrode 12 has a negative electrode current collector exposed portion 41, where the negative electrode mixture layer 42 is not provided on the negative electrode current collector 40, at the axial lower end from the winding start end to the winding end end of the long negative electrode 12. Therefore, the axial lower end of the electrode assembly 14 is formed by the negative electrode current collector exposed portion 41. The negative electrode 12 may form the winding start end of the electrode assembly 14. However, typically, the separator 13 extends beyond the winding start end of the negative electrode 12, and the winding start end of the separator 13 becomes the winding start end of the electrode assembly 14.

[0017] The positive electrode 11 has 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 a metal foil, such as aluminum or an aluminum alloy, that is stable within the potential range of the positive electrode 11, or a film with such a metal disposed on the surface layer. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 can be produced, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, a binder, etc., onto the positive electrode current collector, drying the coating, and then compressing it to form a positive electrode mixture layer on both sides of the positive electrode current collector.

[0018] 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. An example of a preferred lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0019] Examples of the conductive agent contained in the positive electrode mixture layer include carbon materials such as carbon black, acetylene black, ketjen black, and graphite. Examples of the binder contained 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 carboxymethyl cellulose (CMC) or its salts, and polyethylene oxide (PEO).

[0020] The positive electrode 11 is arranged at intervals in the longitudinal direction and has the same number of positive electrode current collector exposed portions as the positive electrode leads 20 in the intermediate portion in the longitudinal direction, excluding both end portions. The positive electrode leads 20 are joined to the positive electrode current collector exposed portions. By joining the multiple positive electrode leads 20 at intervals in the longitudinal direction of the strip-shaped positive electrode current collector, preferably at approximately equal intervals in the longitudinal direction, the current path in the longitudinal direction of the positive electrode 11 can be shortened, and the internal resistance of the battery 10 can be reduced. The positive electrode leads 20 are covered, for example, with insulating tape (not shown), thereby suppressing short circuits between the positive electrode 11 and the negative electrode 12. It is preferable that the insulating tape cover all of the positive electrode current collector exposed portions.

[0021] As shown in FIG. 2 , the negative electrode 12 has a negative electrode current collector 40 and a negative electrode mixture layer 42 formed on both sides of the negative electrode current collector 40. The negative electrode current collector 40 can be made of a metal foil, such as copper or a copper alloy, that is stable within the potential range of the negative electrode 12, or a film with such a metal disposed on its surface. The negative electrode mixture layer 42 contains a negative electrode active material and a binder. The negative electrode 12 can be produced, for example, by applying a negative electrode mixture slurry containing the negative electrode active material and the binder to the negative electrode current collector 40, drying the coating, and then compressing it to form the negative electrode mixture layer 42 on both sides of the negative electrode current collector 40.

[0022] The negative electrode active material generally uses a carbon material that reversibly absorbs and releases lithium ions. Preferred carbon materials include natural graphite such as flake graphite, lump graphite, and amorphous graphite, and artificial graphite such as lump artificial graphite and graphitized mesophase carbon microbeads. The negative electrode mixture layer 42 may contain a silicon (Si) material as the negative electrode active material. Furthermore, the negative electrode active material may include a metal other than Si that alloys with lithium, an alloy containing such a metal, or a compound containing such a metal.

[0023] As in the case of the positive electrode 11, fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, or the like may be used as the binder contained in the negative electrode mixture layer 42, but styrene-butadiene rubber (SBR) or a modified product thereof is preferably used. In addition to SBR or the like, the negative electrode mixture layer may also contain, for example, CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, or the like.

[0024] A porous sheet having ion permeability and insulating properties is used for the separator 13. Specific examples of the porous sheet include a microporous thin film, a woven fabric, and a nonwoven fabric. Preferred materials for the separator 13 include polyolefin resins such as polyethylene and polypropylene, and 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.

[0025] As shown in Figure 1, the battery 10 includes an annular insulating plate 18 on the upper side of the electrode body 14. A positive electrode lead 20 attached to the positive electrode 11 passes through a through-hole in the insulating plate 18 and extends toward the sealing body 17. The sealing body 17 includes an upper current collector plate 50 and a terminal cap 27. The upper current collector plate 50 is a metal annular plate member and has a through-hole 50a in its radial center.

[0026] The terminal cap 27 is a metal plate-like member without a through hole, and is located axially above the sealing body 17. The axially upper end face of the terminal cap 27 is exposed to the outside except for the outer edge, and this exposed portion forms the positive electrode terminal. The sealing body 17 further includes a metal plate 51. The metal plate 51 is an annular metal member. The metal plate 51 has a through hole 51a that is a cylindrical hole.

[0027] Each positive electrode lead 20 is bent from the positive electrode 11 through the through hole 50a of the upper current collector plate 50 so as to fit along the upper surface of the upper current collector plate 50. The tip of each positive electrode lead 20 is sandwiched between the upper surface of the upper current collector plate 50 and the lower surface of the metal plate 51. Each positive electrode lead 20 is bonded to the upper surface of the upper current collector plate 50. The upper current collector plate 50 and the metal plate 51 are also bonded, and each positive electrode lead 20 and the metal plate 51 are also bonded. These bonds can be achieved, for example, by laser welding the tip of each positive electrode lead 20 sandwiched between the upper current collector plate 50 and the metal plate 51 by irradiating the metal plate 51 with a laser beam in the axial direction from above. By laser welding the tip of the positive electrode lead 20 sandwiched between the upper current collector plate 50 and the metal plate 51, the positive electrode lead 20 can be reliably and easily welded and bonded to the upper current collector plate 50.

[0028] The sealing body 17 has a laminated portion 60 on its outer periphery, in which the terminal cap 27 and the upper current collector plate 50 are laminated. By irradiating the laminated portion 60 with a laser beam from above, the terminal cap 27 and the upper current collector plate 50 are laser-welded and electrically connected. The annular upper surface of the upper current collector plate 50 has an annular recess 65 radially inward from the laminated portion 60. Because the upper surface of the upper current collector plate 50 has the recess 65 recessed downward, a space is provided between the terminal cap 27 and the recess 65 of the upper current collector plate 50. Each positive electrode lead 20 is joined to the upper current collector plate 50 within the recess 65. The upper current collector plate 50 does not need to be joined to the metal plate 51, and the positive electrode lead 20 does not need to be joined to the metal plate 51. Furthermore, a cylindrical battery does not need to have a metal plate. Furthermore, the positive electrode lead 20 may be joined to the lower surface of the upper current collector plate 50.

[0029] The battery 10 includes a metal lower current collector plate 52 axially below the electrode assembly 14. Referring to FIGS. 1 and 2 , the electrode assembly 14 is pressed against the upper surface of the lower current collector plate 52 so as to tilt the strip-shaped negative electrode current collector exposed portion 41 radially inward. Laser light is irradiated from the lower surface of the lower current collector plate 52, thereby laser-welding and joining the negative electrode current collector exposed portion 41 to the upper surface of the lower current collector plate 52 over a wide area. Laser light is also irradiated from the lower side of the outer can 16, thereby laser-welding the bottom 68 of the outer can 16 to the lower current collector plate 52. This electrically connects the negative electrode 12 of the electrode assembly 14 to the outer can 16 via the lower current collector plate 52. By joining the negative electrode current collector exposed portion 41 to the upper surface of the lower current collector plate 52 over a wide area, it is possible to prevent current from flowing long distances along the longitudinal direction of the elongated negative electrode 12, thereby reducing the electrical resistance of the battery 10.

[0030] The outer can 16 has a cylindrical portion 39 and a bottom 68. The cylindrical portion 39 includes an annular grooved portion 22 and an annular shoulder portion 29. The grooved portion 22 is formed by spinning a portion of the cylindrical portion 39 to recess it radially inward around the entire circumferential direction. The sealing body 17 is placed on the grooved portion 22 and is fixed to the opening of the outer can 16 by crimping via a resin gasket 28. The shoulder portion 29 is formed when the upper end of the cylindrical portion 39 is bent radially inward and crimped to the flange portion 33 of the sealing body 17, and extends radially inward at the upper end of the cylindrical portion 39.

[0031] The gap between the outer can 16 and the sealing body 17 is sealed with an annular gasket 28, thereby sealing the internal space of the battery 10. The gasket 28 is sandwiched between the outer can 16 and the sealing body 17 and insulates the sealing body 17 from the outer can 16. The gasket 28 serves as a sealant to maintain airtightness inside the battery and as an insulator to insulate the outer can 16 from the sealing body 17. The gasket 28 may have a through-hole 28a. When the nonaqueous electrolyte is a liquid electrolyte (electrolytic solution), providing the through-hole 28a in the gasket 28 facilitates the flow of the electrolyte within the battery 10, thereby improving the circulation of the liquid within the battery 10. The terminal cap 27 electrically connected to the positive electrode lead 20 serves as a positive electrode terminal, and the outer can 16 electrically connected to the negative electrode current collector exposed portion 41 via the lower current collector plate 52 serves as a negative electrode terminal.

[0032] The battery 10 has a thin, easily breakable portion 68a on the bottom 68 of the exterior can 16. The easily breakable portion 68a is formed, for example, by stamping a circle or a C-shape on the underside of the bottom 68. If the bottom 68 has the easily breakable portion 68a, when the battery 10 abnormally heats up, the easily breakable portion 68a breaks, allowing high-temperature gas inside the battery 10 to be discharged to the outside, thereby increasing the safety of the battery 10. The thin, easily breakable portion may also be provided on the terminal cap.

[0033] FIG. 3 is an enlarged cross-sectional view of the periphery of the grooved portion 22 in FIG. 1 . The configurations of the outer can 16 and the cap 30 will be described in detail below with reference to FIGS. 1 and 3 . As shown in FIG. 1 , the cap 30 includes an annular covering portion 81 that covers at least a portion of the outer surface of the shoulder portion 29, a cylindrical portion 82 that extends from the outer peripheral end of the covering portion 81 in a substantially axial direction, and a groove-arrangement portion 83 that is arranged in the annular groove 80 defined by the grooved portion 22. The covering portion 81 is bent radially inward from the upper tip of the cylindrical portion 82 and extends inward, and in the example shown in FIG. 1 , extends substantially parallel to the radial direction. The cylindrical portion 82 extends substantially axially downward from the radially outer end of the covering portion 81. The cap 30 extends from the lower end of the cylindrical portion 82 toward the annular groove 80. The groove-arrangement portion 83 forms the lower tip of the cap 30.

[0034] 1, the covering portion 81 and cylindrical portion 82 of the cap 30 extend along the outer surface of the outer can 16 from the radially inward tip of the shoulder portion 29 of the outer can 16 to the upper end of the grooved portion 22. In the example shown in Fig. 1, the entire outer surface of the shoulder portion 29 contacts the axial lower surface of the covering portion 81, but it is sufficient if at least a portion of the outer surface of the shoulder portion 29 contacts the axial lower surface of the covering portion 81. If the covering portion 81 is joined to the shoulder portion 29 by laser welding or the like, the covering portion 81 can be used as a negative electrode terminal.

[0035] When multiple batteries 10 are electrically connected to form a battery module, for example, an external lead (not shown) is joined to the covering portion 81 of the cap 30 serving as the negative terminal or to the upper surface of the protruding portion 27a of the terminal cap 27 serving as the positive terminal. The radially inner tip of the covering portion may be located radially outward from the radially inner tip of the shoulder portion 29. However, as shown in FIG. 1 , by extending the covering portion 81 radially inward from the shoulder portion 29, when multiple batteries 10 are electrically connected to form a battery module, joining the external lead to the negative terminal is easier than when the shoulder portion 29 is used as the negative terminal without using the cap 30.

[0036] As shown in FIG. 3 , the surface 67 of the grooved portion 22 on the axially lower side (the axial bottom 68 side of the outer can 16) has a recess 70 that opens toward the sealing body 17 in the axial direction. The recess 70 is an annular groove that extends circumferentially around the entire circumference. The groove arrangement portion 83 includes an annular accommodation portion 71 accommodated in the recess 70. The accommodation portion 71 has a barb 73 including an inclined outer surface portion 72 that inclines radially outward toward the bottom in the axial direction. In this embodiment, the barb 73 has an annular structure, the inclined outer surface portion 72 is an inclined outer peripheral surface portion that is provided around the entire circumferential circumference, and the accommodation portion 71 contacts the bottom surface of the recess 70 around the entire circumference.

[0037] The assembly structure of the outer can 16 and the cap 30 can be fabricated, for example, by the following procedure. First, an outer can having a cylindrical portion and a bottom portion that closes the opening on the axial lower side of the cylindrical portion is prepared. Next, the electrode assembly is placed inside the outer can. Next, a predetermined axial range of the cylindrical portion of the outer can is pressed to apply a radially inward force, thereby recessing the predetermined axial range of the cylindrical portion around the entire circumferential direction and creating an annular recess 70.

[0038] Thereafter, a spinning process is performed on a predetermined range in the cylindrical portion axially above the recess-forming portion, to form grooved portion 22 over the entire circumferential direction in that predetermined range. The positions of grooved portion 22 and the formation position of recess 70 are adjusted so that, at the time of forming grooved portion 22, recess 70 is positioned on surface 67 of grooved portion 22 on the axial side of bottom 68. Next, sealing body 17 is placed on grooved portion 22, and the upper end of outer can 16 is crimped radially inward to some extent, and the opening of outer can 16 is sealed with sealing body 17 via gasket 28.

[0039] Next, a cap 30 is prepared, which has a substantially L-shaped half cross section in the axial direction and a ring-shaped protrusion at its lower end that protrudes radially outward. The ring-shaped protrusion corresponds to the barb 73. The cap 30 is placed over the shoulder 29 of the outer can 16 and assembled to the upper end of the outer can 16. Next, with the outer can 16 rotatable about its axial direction, a rotating roller is pressed against a portion of the cap 30 that faces the grooved portion 22 in the radial direction, thereby plastically deforming the lower tip of the cap 30 so that the tip is displaced diagonally downward in the axial direction as it moves radially inward.

[0040] Finally, with the bottom surface of the outer can 16 placed on the top surface of the base, a cylindrical member (not shown) is used to press the top surface of the cap 30 axially downward to form a crimping bond, adjusting the axial length of the grooved portion 22 to a predetermined length and bringing the annular tip portion 88 of the groove arrangement portion 83 into contact with the bottom surface 77 of the recess 70, thereby creating an assembled structure of the outer can 16 and the cap 30.

[0041] In the above configuration, suppose that abnormal heat generation occurs in the battery 10 and the sealing body 17 moves upward due to an increase in the air pressure inside the battery. Then, the cap 30 receives an upward force from the shoulder 29 and moves upward, causing the groove arrangement portion 83 to deform radially outward, in a direction that disengages the annular groove 80. However, as shown in FIG. 4 , this radially outward deformation causes the accommodation portion 71 to catch on the radially outer inner circumferential wall surface 78 of the recess 70, and this catch suppresses further radially outward deformation of the accommodation portion 71. Therefore, suppressing this deformation effectively suppresses the upward movement of the cap 30 and effectively suppresses the upward projection of the sealing body 17.

[0042] Furthermore, because recess 70 is an annular recess, the engagement area of ​​accommodation portion 71 with inner circumferential wall surface portion 78 can be increased, further effectively preventing sealing member 17 from protruding upward. Furthermore, accommodation portion 71 has barbs 73 including inclined outer surface portions 72 that are inclined radially outward as they approach the bottom in the axial direction, so that when accommodation portion 71 deforms radially outward, barbs 73 can be engaged with inner circumferential wall surface portion 78. Therefore, static friction and dynamic friction of accommodation portion 71 with inner circumferential wall surface portion 78 can be increased, further effectively preventing sealing member 17 from protruding upward.

[0043] Furthermore, because the accommodation portion 71 is in contact with the bottom surface of the recess 70 and is high, the accommodation portion 71 is less likely to come off the recess 70, and this more effectively prevents the sealing body 17 from jumping out upward. In order to reliably engage the accommodation portion 71 with the inner circumferential wall surface portion 78, it is preferable that the depth of the recess 70 be 10% or more of the maximum thickness of the grooved portion 22. In addition, in order to ensure sufficient rigidity of the grooved portion 22, it is preferable that the depth of the recess 70 be 40% or less of the maximum thickness of the grooved portion 22.

[0044] The present disclosure is not limited to the above-described embodiment and its variations. Various improvements and modifications are possible within the scope of the claims of the present application and their equivalents. For example, in the above-described embodiment, the sealing body does not include a rupture plate, and the bottom 68 of the outer can 16 includes the easily breakable portion 68a. However, the sealing body may have a laminated structure including two rupture plates (a lower valve body and an upper valve body) and a convex terminal cap covering the rupture plate. Alternatively, the sealing body may be composed of only a rupture plate, or may have a structure in which, from the electrode body side, an internal terminal plate, an insulating plate, and a rupture plate are laminated.

[0045] Also, the case where the negative electrode current collector exposed portion 41 is electrically connected to the bottom 68 of the outer can 16 via the lower current collector plate 52 has been described. However, the negative electrode current collector exposed portion may also be electrically connected to the bottom of the outer can via one or more negative electrode leads. Alternatively, the outermost peripheral surface of the electrode assembly may include the negative electrode current collector exposed portion, and the negative electrode current collector exposed portion on this outermost peripheral surface may be brought into contact with the inner peripheral surface of the outer can, thereby electrically connecting the negative electrode to the outer can. Alternatively, in addition to the contact of the negative electrode current collector exposed portion on the outermost peripheral surface with the inner peripheral surface of the outer can, the negative electrode current collector exposed portion provided at the end of the negative electrode winding start side may also be electrically connected to the bottom of the outer can via a negative electrode lead.

[0046] The case where the axial bottom surface 67 of the grooved portion 22 has an annular recess 70 has been described. However, the axial bottom surface of the grooved portion may have only one non-annular recess that accommodates the accommodating portion of the cap. Alternatively, the axial bottom surface of the grooved portion may have multiple recesses spaced apart in the circumferential direction, each recess accommodating a portion of the tip of the cap. In this case, the axial bottom surface of the grooved portion may have multiple identical recesses spaced apart in the circumferential direction, each recess accommodating a portion of the tip of the cap.

[0047] The cylindrical battery of the present disclosure may also have the following configurations: Configuration 1: A cylindrical battery comprising: an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; a cylindrical outer can with a bottom that houses the electrode assembly and has a tubular portion including a shoulder portion extending radially inward at one axial end and a groove portion recessed radially inward around the entire circumferential circumference, and a bottom portion that closes an opening on the other axial side of the tubular portion; a seal body crimped to an opening of the outer can via a gasket; and an integrated cap including an annular covering portion that covers at least a portion of the outer surface of the shoulder portion, a cylindrical portion extending substantially in the axial direction, and a groove arrangement portion that is arranged in an annular groove defined by the groove arrangement portion, wherein a surface of the groove arrangement portion on the bottom side in the axial direction has a recess that opens toward the seal body in the axial direction, and the groove arrangement portion includes a housing portion housed in the recess. Configuration 2: The cylindrical battery according to Configuration 1, in which the recess is an annular recess. Configuration 3: The cylindrical battery according to Configuration 1 or 2, wherein the housing portion has a barb including an inclined outer surface portion that inclines radially outward toward the bottom side in the axial direction.Configuration 4: The cylindrical battery according to any one of Configurations 1 to 3, wherein the housing portion is in contact with the bottom surface of the recess.Configuration 5: The cylindrical battery according to any one of Configurations 1 to 4, wherein the depth of the recess is 10% to 40% of the maximum thickness of the grooved portion.

[0048] REFERENCE SIGNS LIST 10 Battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16 Outer can, 17 Sealing body, 18 Insulating plate, 20 Positive electrode lead, 22 Grooved portion, 27 Terminal cap, 27a Convex portion, 28 Gasket, 29 Shoulder portion, 30 Cap, 33 Flange portion, 39 Cylindrical portion, 40 Negative electrode current collector, 41 Negative electrode current collector exposed portion, 42 Negative electrode mixture layer, 50 Upper current collector plate, 50a Through hole, 51 Metal plate, 51a Through hole, 52 Lower current collector plate, 60 Lamination portion, 65 Recessed portion, 67 Axial bottom side surface of grooved portion, 68 Bottom portion, 68a Easily breakable portion, 70 Recess, 71 accommodating portion, 72 inclined outer surface portion, 73 return portion, 77 lower surface of recess, 78 inner peripheral wall surface portion, 80 annular groove, 81 covering portion, 82 cylindrical portion, 83 groove arrangement portion, 88 tip portion of groove arrangement portion.

Claims

1. A cylindrical battery comprising: an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween; a bottomed, cylindrical outer can containing the electrode assembly, the cylindrical can having a shoulder extending radially inward at one end in the axial direction and a cylindrical portion including a grooved portion recessed radially inward around the entire circumferential circumference, and a bottom closing an opening on the other side in the axial direction of the cylindrical portion; a seal body crimped and fixed to an opening of the outer can via a gasket; and an integral cap including an annular covering portion covering at least a portion of an outer surface of the shoulder portion, a cylindrical portion extending substantially in the axial direction, and a groove arrangement portion to be arranged in annular groove defined by the grooved portion, wherein a surface of the grooved portion on the bottom side in the axial direction has a recess that opens towards the seal body in the axial direction, and the groove arrangement portion includes a housing portion housed in the recess.

2. The cylindrical battery according to claim 1, wherein the recess is an annular recess.

3. The cylindrical battery according to claim 1 or 2, wherein the storage section has a barb including an inclined outer surface portion that inclines radially outward as it approaches the bottom side in the axial direction.

4. The cylindrical battery according to claim 1 or 2, wherein the storage portion is in contact with a bottom surface of the recess.

5. The cylindrical battery according to claim 1 or 2, wherein the depth of the recess is between 10% and 40% of the maximum thickness of the grooved portion.

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