Power storage device

Abstract

A cylindrical battery (10) is provided with: a cylindrical case (16) having an opening (38); an electrode body disposed in the case (16); a sealing body (17) disposed above the electrode body and electrically connected to the electrode body; and a gasket (28) having a clamped part (40) clamped between the opening (38) and the sealing body (17), and an extending part (41) extending from the clamped part (40) to above the opening (38). The clamped part (40) and the extending part (41) are integrally formed. The extending part (41) has: a protruding part (43) that protrudes from the clamped part (40) to above the opening (38); and a projecting part (45) that projects from the protruding part (43) toward the inside or the outside in the radial direction of the case (16).

Description

Power storage device

[0001] The present disclosure relates to a power storage device, for example, a cylindrical battery, a capacitor, or the like.

[0002] Conventionally, as a power storage device, there is a cylindrical battery described in Patent Document 1. This cylindrical battery includes an electrode body, a bottomed cylindrical case that houses the electrode body, a sealing body that closes the opening of the case, and a gasket sandwiched between the case and the sealing body. The electrode body has a structure in which a positive electrode and a negative electrode are wound with a separator interposed therebetween. The positive electrode and the sealing body are electrically connected via a positive electrode lead, and the negative electrode and the bottom of the case are electrically connected via a negative electrode lead.

[0003] Japanese Patent Application Laid-Open No. 09-274923

[0004] In a battery module using a power storage device, there are demands such as arranging batteries at high density to increase the energy density per unit volume, and arranging a cooling device below the battery in the height direction. In order to achieve high performance based on these demands, further improvement in reliability is required. Therefore, an object of the present disclosure is to provide a power storage device that is easy to achieve high reliability.

[0005] To solve the above problems, a power storage device according to the present disclosure includes a cylindrical case having an opening, an electrode body disposed in the case, a sealing body disposed above the electrode body and electrically connected to the electrode body, a sandwiching portion sandwiched between the opening of the case and the sealing body, and a gasket having an extending portion extending from the sandwiching portion above the opening, wherein the sandwiching portion and the extending portion are integrally formed, and the extending portion has a protruding portion protruding from the sandwiching portion above the opening, and a protruding portion protruding inward or outward in the radial direction of the case from the protruding portion.

[0006] The phrase "projection projecting radially inward or outward" above means that the projection includes at least one of a first projection projecting radially inward and a first projection projecting radially outward. In other words, the projection may have the first projection but not the second projection, or it may have the second projection but not the first projection. Alternatively, the projection may have both the first and second projections.

[0007] The energy storage device described herein makes it easier to achieve high reliability.

[0008] This is an axial cross-sectional view of a cylindrical battery according to one embodiment of the present disclosure. This is a perspective view of the electrode body of the cylindrical battery. This is an enlarged cross-sectional view of the upper end of the cylindrical battery. This is a top view of the cylindrical battery as seen from the axial upper side. This is a schematic top view of the projection of the gasket of the first modified example and the tip side of the first lead as seen from the axial upper side. This is a schematic half cross-sectional view of the gasket of the second modified example in the axial direction. This is a schematic half cross-sectional view of the gasket of the third modified example in the axial direction. This is a schematic half cross-sectional view of the gasket of the fourth modified example in the axial direction. This is a schematic half cross-sectional view of the gasket of the fifth modified example in the axial direction. This is a schematic cross-sectional view showing the cross-section of the tip of the first lead and a schematic half cross-section of the gasket of the sixth modified example in the axial direction. This is a schematic cross-sectional view showing the cross-section of the tip of the first lead and a schematic half cross-section of the gasket of the seventh modified example in the axial direction.

[0009] Hereinafter, embodiments of the energy storage device according to this disclosure will be described in detail with reference to the drawings. In the following, a cylindrical secondary battery using a non-aqueous electrolyte, more specifically a lithium-ion cylindrical secondary battery 10, will be given as an example of an energy storage device according to one embodiment, but the energy storage device of this disclosure is not limited to this. The energy storage device of this disclosure is not limited to a battery using a non-aqueous electrolyte, but may also be a battery using an aqueous electrolyte. Furthermore, the energy storage device of this disclosure is not limited to a secondary battery, but may also be a primary battery. Furthermore, the energy storage device of this disclosure may be a battery other than a cylindrical battery, for example, a prismatic battery, etc. Furthermore, the energy storage device of this disclosure may be a capacitor (capacitor) instead of a battery.

[0010] It is intended from the outset that new embodiments can be constructed by appropriately combining the characteristic features of the embodiments and modifications described below. In the following embodiments, the same reference numerals are used for the same components in the drawings, and redundant explanations are omitted. In addition, multiple drawings include schematic diagrams, and the dimensional ratios such as length, width, and height of each component do not necessarily match between different drawings. In this specification, the axial (height direction) sealing body 17 side of the lithium-ion cylindrical secondary battery (hereinafter simply referred to as cylindrical battery) 10 is referred to as "upper," and the axial bottom 68 side of the case 16 is referred to as "lower." In addition, among the components described below, components that are not described in the independent claim indicating the highest-level concept are optional components and are not essential components.

[0011] Figure 1 is an axial cross-sectional view of a cylindrical battery 10 according to one embodiment of the present disclosure, and Figure 2 is a perspective view of the electrode body 14 of the cylindrical battery 10. As shown in Figure 1, the cylindrical battery 10 comprises a wound electrode body 14, a non-aqueous electrolyte (not shown), a bottomed cylindrical metal case (outer can) 16 that houses the electrode body 14 and the non-aqueous electrolyte, and a sealing body 17 that closes the opening (shoulder portion) 38 of the case 16 via a gasket 28. In this embodiment, the case 16 has a bottomed cylindrical shape, but the case may also have a cylindrical shape with openings at both ends in the axial direction, and the cylindrical battery may have a configuration in which these two openings are closed.

[0012] As shown in Figure 2, the electrode body 14 has a wound structure in which a long positive electrode 11 and a long negative electrode 12 are wound around two long separators 13. The positive electrode 11 is an example of a first electrode, and the negative electrode 12 is an example of a second electrode. The negative electrode 12 is formed to be slightly larger than the positive electrode 11 in order to prevent lithium deposition. That is, the negative electrode 12 is formed to be longer than the positive electrode 11 in both the longitudinal and widthwise (short-side) directions. The two separators 13 are formed to be at least slightly larger than the positive electrode 11 and are arranged, for example, to sandwich the positive electrode 11. The negative electrode 12 may constitute the starting end of the winding of the electrode body 14. However, generally, the separators 13 extend beyond the starting end of the winding of the negative electrode 12, and the starting end of the winding of the separators 13 becomes the starting end of the winding of the electrode body 14.

[0013] Non-aqueous electrolytes are ionic conductive (e.g., lithium ion conductive). Non-aqueous electrolytes may be liquid electrolytes (electrolytes) or solid electrolytes. Liquid electrolytes (electrolytes) contain 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. Non-aqueous solvents may contain halogen-substituted compounds (e.g., fluoroethylene carbonate) in which at least some of the hydrogen atoms in these solvents are replaced with halogen atoms such as fluorine. Examples of electrolyte salts include LiPF4. ６ Lithium salts such as these are used.

[0014] As solid electrolytes, for example, solid or gel-like polymer electrolytes, inorganic solid electrolytes, etc., are used. Polymer electrolytes include, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt and a matrix polymer. As matrix polymers, for example, polymer materials that absorb non-aqueous solvents and gel are used. As polymer materials, for example, fluororesins, acrylic resins, polyether resins, etc., are used. As inorganic solid electrolytes, for example, materials known for all-solid-state lithium-ion secondary batteries, etc. (for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.) are used.

[0015] The positive electrode 11 comprises a positive electrode current collector and a positive electrode mixture layer formed on both sides of the positive electrode current collector. The positive electrode current collector can be made of a metal foil that is stable within the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film with the metal arranged on its surface. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 can be manufactured, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder onto the positive electrode current collector, drying the coating, and then compressing it to form the positive electrode mixture layer on both sides of the current collector.

[0016] The positive electrode active material is mainly composed of a lithium-containing metal composite oxide. Examples of metal elements contained in the lithium-containing metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, and W. A preferred example of a lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0017] Examples of conductive agents included in the positive electrode mixture layer include carbon blacks such as acetylene black and Ketjen black, and carbon materials such as graphite. Examples of binders included in the positive electrode mixture layer include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, and polyolefin resins. These resins may be used in combination with cellulose derivatives such as carboxymethylcellulose (CMC) or its salts, polyethylene oxide (PEO), etc.

[0018] The negative electrode 12 comprises a negative electrode current collector and a negative electrode mixture layer formed on both sides of the negative electrode current collector. The negative electrode current collector can be made of a metal foil that is stable within the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with the metal arranged on its surface. The negative electrode mixture layer contains a negative electrode active material and a binder. The negative electrode 12 can be manufactured, for example, by applying a negative electrode mixture slurry containing the negative electrode active material and binder onto the negative electrode current collector, drying the coating, and then compressing it to form the negative electrode mixture layer on both sides of the current collector.

[0019] Generally, carbon materials that reversibly intercept and release lithium ions are used as the negative electrode active material. Preferred carbon materials are graphite such as natural graphite such as flake graphite, lump graphite, and clay graphite, and artificial graphite such as lump graphite and graphitized mesophase carbon microbeads. The negative electrode mixture layer may contain silicon (Si) material as the negative electrode active material. In addition, metals that alloy with lithium other than Si, alloys containing such metals, compounds containing such metals, etc., may be used as the negative electrode active material.

[0020] The binder included in the negative electrode mixture layer may be fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, etc., as in the case of the positive electrode 11, but preferably styrene-butadiene rubber (SBR) or a modified version thereof is used. In addition to SBR, the negative electrode mixture layer may also contain, for example, CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, etc.

[0021] A porous sheet having ion permeability and insulating properties is used for the separator 13. Specific examples of porous sheets include microporous thin films, woven fabrics, and nonwoven fabrics. The material of the separator 13 is preferably polyethylene, polyolefin resins such as polypropylene, or cellulose. The separator 13 may have either a single-layer structure or a laminated structure. A heat-resistant layer or the like may be formed on the surface of the separator 13.

[0022] As shown in Figure 1, a positive electrode lead 20 is joined to the positive electrode 11, and a negative electrode lead 21 is joined to the end of the negative electrode 12 on the winding end side in the longitudinal direction. The cylindrical battery 10 has an insulating plate 18 above the electrode body 14 and an insulating plate 19 below the electrode body 14. One end of the positive electrode lead 20 is joined to the positive electrode current collector of the positive electrode 11 of the electrode body 14. In this embodiment, the sealing body 17 is composed of only one sealing plate (rupture plate). The tip of the positive electrode lead 20 passes through the through hole in the insulating plate 18, then bends radially inward, and further bends into a U-shape before being joined by welding or the like to the inner surface (bottom surface) 30 on the electrode body 14 side in the axial direction of the sealing body 17. The sealing body 17 electrically connected to the positive electrode 11 serves as the positive electrode terminal.

[0023] The negative electrode lead 21 extends from the outside of the insulating plate 19 towards the bottom 68 of the case 16. The negative electrode lead 21 is joined to the inner surface of the bottom 68 of the metal case 16 by welding or the like, so that the case 16 becomes the negative electrode terminal. In the example shown in Figures 1 and 2, the positive electrode lead 20 is electrically connected to an intermediate part of the positive electrode current collector, such as the center in the winding direction, and the negative electrode lead 21 is electrically connected to the end of the negative electrode current collector, on the winding end side in the winding direction.

[0024] However, the positive electrode lead 20 may be electrically connected to a location other than the middle portion in the winding direction of the positive electrode current collector, and the negative electrode lead may be electrically connected to the winding start end in the winding direction of the negative electrode current collector. Alternatively, the electrode body may have two negative electrode leads, with one negative electrode lead electrically connected to the winding start end in the winding direction of the negative electrode current collector and the other negative electrode lead electrically connected to the winding end in the winding direction of the negative electrode current collector. Alternatively, the negative electrode and the case may be electrically connected by bringing the winding end in the winding direction of the negative electrode current collector into contact with the inner surface of the case.

[0025] Furthermore, there may be multiple positive leads (for example, eight positive leads) joined to the positive electrode current collector at intervals in the winding direction, and these multiple positive leads may be joined to a metal current collector plate joined to the lower surface of the sealing body. Alternatively, the upper end of the positive electrode current collector may constitute the upper end of the electrode body, and the upper end of the positive electrode current collector may be joined to a metal current collector plate included in the sealing body. In addition, the lower end of the negative electrode current collector may constitute the lower end of the electrode body, and the lower end of the negative electrode current collector may be joined to the current collector plate by welding or the like. Furthermore, the current collector plate to which the lower end of the negative electrode current collector is joined may be joined to the bottom of the case by welding or the like.

[0026] As shown in Figure 1, the sealing body (sealing plate) 17 has an annular outer edge portion 51 formed radially outward, a terminal portion 52 formed radially inward, and an annular thin-walled portion 53 that connects the outer edge portion 51 and the terminal portion 52 and is thinner than the terminal portion 52. As shown in Figure 1, the upper and lower surfaces of the thin-walled portion 53 each have inclined surfaces that are displaced axially upward as they extend radially outward. The axial thickness of the thin-walled portion 53 decreases as it extends radially outward.

[0027] The cylindrical battery 10 has a resin gasket 28 positioned between the case 16 and the sealing body 17. The gasket 28 is preferably made of an insulating material with excellent compressibility and resistance, such as PP (polypropylene), PPS (polyphenylene sulfide), PFA (perfluoroalkoxyalkane), or PPT (polypropylene terephthalate). The outer edge 51 of the sealing body 17 is crimped and fixed to the opening 38 of the case 16 via the gasket 28. This seals the internal space of the cylindrical battery 10. The gasket 28 is compressed and sandwiched between the case 16 and the outer edge 51, insulating the sealing body 17 from the case 16. The gasket 28 serves as a sealing material to maintain airtightness inside the battery and as an insulating material to insulate the case 16 from the sealing body 17.

[0028] The case 16 has an opening 38, a grooved portion 34, a cylindrical portion 50, and a bottom portion 68, and houses the electrode body 14 and a non-aqueous electrolyte. The grooved portion 34 can be formed, for example, by spinning a part of the side surface of the case 16 radially inward to create an annular recess radially inward. The opening 38 is formed when the outer edge portion 51 is crimped and fixed to the case 16, by bending the upper end of the case 16 inward toward the outer edge portion 51.

[0029] When the cylindrical battery 10 overheats and its internal pressure rises, the sealing body 17 is pressed upward by the gas pressure, causing the thin-walled portion 53 to reverse from a downward slope starting from the annular outer edge 54 to an upward slope, and the outer edge 54 ruptures, releasing the gas. This release of gas prevents the cylindrical battery 10 from rupturing due to an excessive rise in internal pressure, thereby increasing the safety of the cylindrical battery 10.

[0030] The case described above has been one in which the sealing body 17 is composed of only one sealing plate (rupture plate). However, the sealing body may have a laminated structure including two rupture plates (lower valve body and upper valve body) and a convex terminal cap that covers the rupture plate. Alternatively, the sealing body may have a structure in which an internal terminal plate, an annular insulating plate, and a rupture plate are laminated in order from the electrode body side. Alternatively, the sealing body may not have a rupture plate, and the bottom of the case may have a thin, easily breakable portion that breaks when the battery overheats abnormally.

[0031] Figure 3 is an enlarged cross-sectional view of the upper end of the cylindrical battery 10. As shown in Figure 3, the gasket 28 is integrally formed and has a clamping portion 40 that is sandwiched between the opening 38 of the case 16 and the sealing body 17, and an extending portion 41 that extends from the clamping portion 40 to above the opening 38. The extending portion 41 has a protruding portion 43 that extends above the opening 38 via an overhanging portion 42 that protrudes radially inward from the clamping portion 40 to above the opening 38, and a projection 45 that protrudes radially from the protruding portion 43.

[0032] The projection 45 includes a first projection 46 that protrudes radially outward from the projection 43 and a second projection 47 that protrudes radially inward from the projection 43. The tip of the opening 38 is in contact with the clamping portion 40 of the gasket 28. As shown in Figure 3, in this embodiment, the first projection 46 protrudes from the tip of the projection 43 toward the radially outward region in a direction substantially parallel to the radial direction. The second projection 47 protrudes from the tip of the projection 43 toward the radially inward region in a direction substantially parallel to the radial direction. However, the first projection may protrude from the tip of the projection 43 in a direction that includes both a radial component and an axial component. More specifically, the first projection 46 may protrude from the tip of the projection 43 toward the opening 38 (axial direction) and toward the radially outward region. Also, the second projection 47 may protrude from the tip of the projection 43 in a direction that includes both a radial component and an axial component. More specifically, the first projection 46 may project from the tip of the projection 43 in a direction toward the opening 38 (axial direction) and toward the radially inward region. Alternatively, the first projection 46 may project from the midpoint of the height of the projection 43 toward the radially outward region, and the second projection 47 may project from the midpoint of the height of the projection 43 toward the radially inward region. In other words, the first projection 46 and the second projection 47 may be inclined so that they move toward the opening 38 in the axial direction as they move away from the projection 43 in the radial direction.

[0033] The cylindrical battery 10 further comprises a first lead 60 joined to an opening 38 and a second lead 70 joined to the upper surface of a sealing body 17. In this embodiment, the first lead 60 is joined to the opening 38 by welding, and the second lead 70 is joined to the upper surface of the sealing body 17 by welding. The first lead 60 is composed of a portion cut and bent from a plate-shaped part (not shown) of a first current collector plate used to electrically connect a plurality of cylindrical batteries 10 in a battery module. Figure 4 is a top view of the cylindrical battery 10 as seen from the axial upper side. As shown in Figures 3 and 4, the tip portion 60a of the first lead 60 overlaps the first projection 46 in the axial direction when viewed from above. The second lead 70 is composed of a portion cut and bent from a plate-shaped part (not shown) of a second current collector plate used to electrically connect a plurality of cylindrical batteries 10 in a battery module. As shown in Figure 3, the second lead 70 includes a first portion 71 located above the projection 45 and a second portion 72 welded to the sealing body 17. Note that the first lead 60 and the second lead 70 are separate from the plate-like portion, and one end of each may be joined to the plate-like portion.

[0034] In conventional cylindrical batteries having a gasket without an extended portion as disclosed herein, there is a risk that the conductive portion, composed of external metal foreign matter, may bridge the gap between the opening and the sealing body. Thus, the conventional gasket cannot prevent the conductive portion from electrically connecting the opening and the sealing body. Furthermore, in the conventional gasket, there is a risk that the first lead joined to the opening may move towards the sealing body and ride up onto the sealing body. Also, in the conventional gasket, there is a risk that the second lead welded to the sealing body may come into contact with the opening. Moreover, if at least one of the first lead and the second lead becomes detached due to vibration or shock after the cylindrical battery has been manufactured, there is a risk that the gasket may cause at least one of the detached first lead and second lead to electrically connect the opening and the sealing body.

[0035] In contrast, with the cylindrical battery 10, as shown in Figure 3, the gasket 28 has a protruding portion 43 that extends from the clamping portion 40 to above the opening 38, and a projection 45 that protrudes radially from the protruding portion 43 toward the case 16. This prevents conductive portions made of external metal foreign objects from electrically connecting the opening 38 and the sealing body 17, as the projection 45 prevents this.

[0036] Furthermore, the projection 45 can prevent the first lead 60, which is welded to the opening 38, from moving towards the sealing body and riding up onto the sealing body 17, and also prevent the second lead 70, which is welded to the sealing body 17, from coming into contact with the opening 38. For example, the projection 45 can also prevent at least one of the first lead 60 and the second lead 70, which may have come off due to vibration or shock, from electrically connecting the opening 38 and the sealing body 17. Therefore, in the cylindrical battery 10, high reliability can be achieved even when the opening 38 of the case 16 is used as the negative terminal.

[0037] Furthermore, the gasket 28 has a projection 43 extending in the height direction and a projection 45 projecting radially from the projection 43 toward the case 16. The first projection 46 of the projection 45 overlaps axially with the tip 38a of the opening 38 when viewed from above. Therefore, the presence of the first projection 46 increases the insulation distance from the opening 38 to the sealing body 17, thereby suppressing the electrical connection of the opening 38 to the sealing body 17 by metallic foreign matter.

[0038] Furthermore, the cylindrical battery 10 includes a first lead 60 welded to the opening 38, and the tip 60a of the first lead 60 axially overlaps with the first projection 46 when viewed from above. More specifically, the first projection 46 includes an overlapping portion that axially overlaps with the opening 38 when viewed from above, and this overlapping portion overlaps with the tip 60a of the first lead 60 when viewed from above. Therefore, by connecting the first lead 60 so that it fits under the first projection 46, misalignment of the first lead 60 during connection can be suppressed. Moreover, short circuits caused by misalignment of the first lead 60 when the joint (welded portion in this embodiment) of the first lead 60 breaks can also be suppressed.

[0039] Furthermore, the second lead 70, which is welded to the sealing body 17, has a first portion 71 located above the projection 45. The insulating first projection 46 is interposed between the second lead 70 (the first portion 71 of the second lead 70) and the opening 38. Therefore, contact between the second lead 70 and the opening 38 can be suppressed, and as a result, short circuits can be suppressed.

[0040] Furthermore, the sealing body 17 has a joint portion (a welded portion in this embodiment) to which the second lead 70 is joined, and a thin-walled portion 53 provided to surround the joint portion. In addition, the thin-walled portion 53 that breaks when the cylindrical battery 10 overheats is located radially inward from the protruding portion 43. Therefore, when the cylindrical battery 10 overheats, the molten metal that flows to the outside through the broken thin-walled portion 53 is guided radially inward by the protruding portion 43 and is less likely to scatter over a wide area. As a result, the molten metal is less likely to come into contact with the opening 38. Thus, the safety when the cylindrical battery 10 overheats can be increased.

[0041] Furthermore, the gasket 28 includes a first projection 46 that protrudes radially outward from the projection 43 and a second projection 47 that protrudes radially inward from the projection 43. Therefore, when welding the first lead 60 positioned below the first projection 46, the second projection 47 can be pressed downward, causing the first projection 46 to deform so that it is displaced (tilted) upward as it moves radially outward. As a result, when positioning the first lead 60 below the first projection 46, the first lead 60 is less likely to come into contact with the first projection 46. Also, the opening 38 into which the first lead 60 is welded becomes easier to see from above. Therefore, when welding the first lead 60 below the first projection 46, the first projection 46 is less likely to be damaged, and welding the first lead 60 to the opening 38 can be easily performed.

[0042] This disclosure is not limited to the embodiments and their modifications, and various improvements and modifications are possible within the scope of the claims of this application and their equivalents.

[0043] FIG. 5 is a schematic top view when looking at the protrusion 145 of the gasket 128 of the first modification and the tip side of the first lead 60 from the upper side in the axial direction. In the above embodiment, the first protrusion 46 had an overlapping portion that axially overlapped the first lead 60 when viewed from the axial direction (height direction). However, as shown in FIG. 5, the protrusion 145 may have a concave portion 115 that overlaps the first lead 60 when viewed from above and has openings on both axial sides in the axial direction. The concave portion 115 may be recessed from the outer side to the inner side in the radial direction of the case. By doing so, the visibility from above of the first lead 60 can be improved, and the first lead 60 can be easily joined to the opening by laser welding or the like from above. In the example shown in FIG. 5, the concave portion 115 does not axially overlap the first lead 60. However, a configuration in which the inner edge portion of the concave portion 115 axially overlaps the outer edge portion of the tip end portion of the first lead 60 may also be possible.

[0044] FIG. 6 is a schematic half cross-sectional view in the axial direction of the gasket 228 of the second modification, and FIG. 7 is a schematic half cross-sectional view in the axial direction of the gasket 328 of the third modification. As shown in FIGS. 6 and 7, the maximum thickness in the axial direction (axial direction of the case) of the protrusions 243, 343 may be larger than the maximum thickness in the radial direction (radial direction of the case) of the protrusions 243, 343. By doing so, even when an impact is applied to the gaskets 228, 328 from above, it becomes difficult for the gaskets 228, 328 to fall down, so the short-circuit suppression effect of the gaskets 228, 328 tends to be high, and damage to the gaskets 228, 328 is also likely to be suppressed.

[0045] FIG. 8 is an axial schematic half-sectional view of the gasket 428 of the fourth modification, and FIG. 9 is an axial schematic half-sectional view of the gasket 528 of the fifth modification. As shown in FIGS. 8 and 9, the protruding portions 443 and 543 may be inclined so as to face radially outward of the case as they go upward. Also, as shown in FIG. 9, a groove 592 that recesses radially inward may be provided at the lower end of the tapered outer peripheral surface 591 of the protruding portion 543. In this way, when a load is applied to the gaskets 428 and 528 from above, the protruding portions 443 and 543 can be intentionally tilted radially outward. Therefore, since the first lead 60 (not shown in FIGS. 8 and 9) can be covered by the tilted protruding portions 443 and 543, a short circuit related to the first lead 60 when a load is applied to the gaskets 428 and 528 from above can be effectively suppressed. Also, since the opening 38 can be covered by the tilted protruding portions 443 and 543, a short circuit between the opening 38 and the sealing body 17 through a metallic foreign object or the like can also be suppressed.

[0046] FIG. 10 is a schematic cross-sectional view showing a cross-section of the tip of the first lead 60 and an axial schematic half-section of the gasket 628 of the sixth modification. As shown in FIG. 10, the lower end 646a of the first protruding portion 646 that protrudes radially outward from the protruding portion 643 that protrudes in the height direction may be located below the lower end 647a of the second protruding portion 647 that protrudes radially outward from the protruding portion 643. In this way, since the floating of the welding portion of the first lead 60 can be suppressed by the tip of the first protruding portion 646, the displacement of the first lead 60 can be effectively suppressed. Although the opening 38 of the case 16 is disposed between the first lead 60 and the gasket 628, it is omitted in FIGS. 10 and 11.

[0047] Also, as shown in FIG. 10, the outer tip 646b in the radial direction of the first protruding portion 646 may be located below the upper end 646c of the first protruding portion 646. Even in this way, since the floating of the welding portion of the first lead 60 can be suppressed by the tip of the first protruding portion 646, the displacement of the first lead 60 can be effectively suppressed.

[0048] As shown in Figure 3, the case in which the extended portion 41 includes a projection 45 formed by branching from or bending from the projection 43 will be described. Furthermore, the case in which the first projection 46 of the extended portion 41 extends above the first lead 60 and substantially parallel to the radial direction will be described. Finally, the case in which the first projection 46 has an overlapping portion that overlaps the tip of the first lead 60 in the axial direction will be described.

[0049] However, as shown in Figure 11, a schematic cross-sectional view showing the cross-section of the tip of the first lead 60 and a schematic half-section of the gasket 728 in the axial direction of the seventh modified example, the extended portion 641 may have a linear shape that slopes upward in the axial direction as it extends radially outward in the axial cross-section, and the protruding portion 643 and the first projection 646 may extend in substantially the same direction. In this case as well, by making the extended portion 641 protrude radially outward from the case and above the first lead 60, and by making the first projection 646 constituting the tip of the extended portion 641 have an overlapping portion that axially overlaps the tip of the first lead 60, short circuits can be effectively suppressed.

[0050] The extended portion does not have to be provided around the entire circumference, but may be provided only on a part of the circumference. It is preferable to provide the extended portion so that a part of it is located in the circumferential range where at least a part of at least one of the first lead and the second lead is present, in order to effectively suppress short circuits. The gasket may also be molded integrally with the sealing body by insert molding in the shape of the case opening (shoulder portion) after crimping, in which case it is possible to suppress the gasket from interfering with the crimping of the opening in the final step.

[0051] Even if the gasket is not molded integrally with the sealing body by insert molding, the cylindrical battery of this disclosure can be smoothly manufactured by plastically deforming the opening radially inward by spin crimping. Furthermore, even if the gasket has a complex shape, the gasket can be easily manufactured simply by making the shape of the resin material injection space in injection molding correspond to the shape of the gasket.

[0052] The case described above has been in which the first electrode of the cylindrical battery 10 is a positive electrode 11, which is electrically connected to the sealing body 17, and the second electrode of the cylindrical battery 10 is a negative electrode 12, which is electrically connected to the case 16. However, it is also possible to have a configuration in which the first electrode of the cylindrical battery is a negative electrode, which is electrically connected to the sealing body, and the second electrode of the cylindrical battery is a positive electrode, which is electrically connected to the case.

[0053] Although the case in which the sealing body 17 is fixed to the case 16 by crimping has been described, the sealing body may also be fixed to the case by laser welding. Furthermore, the extended portion only needs to include at least one of the first projection and the second projection, and either the first projection or the second projection may be omitted.

[0054] Furthermore, the energy storage device of this disclosure may have the following configurations: Configuration 1: An energy storage device comprising a cylindrical case having an opening, an electrode body disposed inside the case, a sealing body disposed above the electrode body and electrically connected to the electrode body, and a gasket having a clamping portion sandwiched between the opening of the case and the sealing body, and an extending portion extending from the clamping portion to above the opening, wherein the clamping portion and the extending portion are integrally formed, and the extending portion has a protruding portion that extends from the clamping portion to above the opening, and a projection that protrudes inward or outward in the radial direction of the case from the protruding portion. Configuration 2: The energy storage device according to Configuration 1, wherein the sealing body is composed only of a sealing plate. Configuration 3: The energy storage device according to Configuration 1 or 2, wherein the projection includes a first projection that protrudes radially outward from the protruding portion of the case, the tip of the opening is in contact with the clamping portion, and the first projection includes an overlapping portion that axially overlaps with the opening when viewed from above. Configuration 4: The energy storage device according to Configuration 3, further comprising a first lead joined to the opening, wherein the first projection includes an overlapping portion that axially overlaps with the tip of the first lead when viewed from above. Configuration 5: The energy storage device according to any one of Configurations 1 to 4, comprising a second lead connected to the sealing body, wherein the electrode body comprises a first electrode, a second electrode having a different polarity from the first electrode, and a separator disposed between the first electrode and the second electrode, the first electrode and the second electrode being wound around the separator, the sealing body being electrically connected to the first electrode, the opening being electrically connected to the second electrode, and the second lead comprising a first portion located above the projection and a second portion joined to the sealing body. Configuration 6: The energy storage device according to Configuration 5, wherein the sealing body comprises a joint to which the second lead is joined, a thin-walled portion provided so as to surround the joint and electrically connected to the first electrode, and an outer edge portion provided so as to surround the thin-walled portion and pressing the clamping portion of the gasket, the thin-walled portion being located radially inward from the projection.Configuration 7: The projection has a recess in a position that overlaps the first lead in the axial direction when viewed from above, and the recess is recessed from the radially outer side to the radially inner side of the case, as described in Configuration 4. Configuration 8: The maximum axial thickness of the case at the projection is greater than the maximum radial thickness of the case at the projection, as described in any one of Configurations 1 to 7. Configuration 9: The projection is inclined to move radially outward of the case as it moves upward in the axial direction, as described in any one of Configurations 1 to 8. Configuration 10: The projection includes a second projection that protrudes radially inward from the projection towards the radially inner side of the case, as described in Configuration 4. Configuration 11: The lower end of the first projection is located below the lower end of the second projection, as described in Configuration 10. Configuration 12: The radially outer tip of the first projection is located below the upper end of the first projection, as described in Configuration 4. Configuration 13: An energy storage device comprising: a cylindrical case having an opening; an electrode body disposed inside the case; a sealing body disposed above the electrode body and electrically connected to the electrode body; a gasket having a clamping portion sandwiched between the opening of the case and the sealing body, and an extending portion extending from the clamping portion to above the opening; and a first lead joined to the opening, wherein the clamping portion and the extending portion are integrally formed, the tip of the opening is in contact with the clamping portion of the gasket, the extending portion protrudes radially outward from the clamping portion to above the first lead, and the extending portion includes an overlapping portion that axially overlaps with the tip of the first lead.

[0055] 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16 Case, 17 Sealing body, 18 Insulating plate, 19 Insulating plate, 20 Positive electrode lead, 21 Negative electrode lead, 28, 128, 228, 328, 428, 528, 628, 728 Gasket, 34 Grooved portion, 38 Opening (shoulder portion), 38a Tip of opening, 40 Clamping portion, 41, 641 Extendable portion, 42 Overhanging portion, 43, 243, 443, 543, 643 Protruding portion, 45, 145 Projection portion, 46, 646 First projection portion, 47, 647 Second projection portion, 50 Cylindrical portion, 51 Outer edge portion, 52 Terminal portion, 53 Thin-walled portion, 54 Outer edge of thin-walled portion, 60 First lead, 60a Tip of the first lead, 68 Bottom portion, 70 Second lead, 71 First portion, 72 Second portion, 115 Recess, 591 Tapered outer surface, 592 Groove, 646a Lower end of the first projection, 647a Lower end of the second projection.

Claims

1. An energy storage device comprising: a cylindrical case having an opening; an electrode body disposed inside the case; a sealing body disposed above the electrode body and electrically connected to the electrode body; a gasket having a clamping portion sandwiched between the opening of the case and the sealing body, and an extending portion extending from the clamping portion to above the opening, wherein the clamping portion and the extending portion are integrally formed, and the extending portion has a protruding portion that extends from the clamping portion to above the opening, and a projection that protrudes from the protruding portion inward or outward in the radial direction of the case.

2. The energy storage device according to claim 1, wherein the sealing body is composed solely of a sealing plate.

3. The energy storage device according to claim 1, wherein the projection includes a first projection that protrudes radially outward from the protruding portion of the case, the tip of the opening is in contact with the clamping portion, and the first projection includes an overlapping portion that overlaps the opening in the axial direction when viewed from above.

4. The energy storage device according to claim 3, comprising a first lead joined to the opening, wherein the overlapping portion overlaps with the tip of the first lead when viewed from above.

5. The energy storage device according to claim 1 or 4, further comprising a second lead connected to the sealing body, wherein the electrode body comprises a first electrode, a second electrode having a polarity different from that of the first electrode, and a separator disposed between the first electrode and the second electrode, the first electrode and the second electrode being wound around the separator, the sealing body being electrically connected to the first electrode, the opening being electrically connected to the second electrode, and the second lead comprising a first portion located above the projection and a second portion joined to the sealing body.

6. The sealing body has a joint portion to which the second lead is joined, a thin-walled portion provided so as to surround the joint portion, and an outer edge portion provided so as to surround the thin-walled portion and presses against the clamping portion of the gasket, wherein the thin-walled portion is located radially inward from the protruding portion, the energy storage device according to claim 5.

7. The projection is provided with a recess at a position that overlaps with the first lead in the axial direction when viewed from above, and the recess is recessed from the radially outer side to the inner side of the case, as described in claim 4.

8. The energy storage device according to claim 1, wherein the maximum axial thickness of the case at the protrusion is greater than the maximum radial thickness of the case at the protrusion.

9. The energy storage device according to claim 1, wherein the protrusion is inclined so as it extends upward in the axial direction, it extends outward in the radial direction of the case.

10. The energy storage device according to claim 4, wherein the projection includes a second projection that protrudes radially inward from the projection towards the case.

11. The energy storage device according to claim 10, wherein the lower end of the first projection is located below the lower end of the second projection.

12. The energy storage device according to claim 4, wherein the radially outer tip of the first projection is located below the upper end of the first projection.

13. An energy storage device comprising: a cylindrical case having an opening; an electrode body disposed inside the case; a sealing body disposed above the electrode body and electrically connected to the electrode body; a gasket having a clamping portion sandwiched between the opening of the case and the sealing body, and an extending portion extending from the clamping portion to above the opening; and a first lead joined to the opening, wherein the clamping portion and the extending portion are integrally formed, the tip of the opening is in contact with the clamping portion of the gasket, the extending portion protrudes radially outward from the clamping portion to above the first lead, and the extending portion includes an overlapping portion that axially overlaps with the tip of the first lead.

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