Power storage device

Abstract

A battery (10) comprises a negative electrode current collector plate (19) that is disposed below an electrode body (14) and has an annular or C-shaped body part (60) that is fixed to a bottom part (68) and a protruding part (61) that protrudes from the body part (60) to the inside of the body part (60) and is electrically connected to the electrode body (14). The bottom part (68) has: a fixing part (71) to which the body part (60) is fixed; and a fragile part (72) which is positioned further toward the inside than the fixing part (71) when viewed from above, and which is thinner than the fixing part (71). The fragile part (72) is positioned inside the body part (60) with a distance from the body part (60) when viewed from above. The fragile part (72) is positioned inside the inner periphery of the body part (60) when viewed from above.

Description

Power storage device

[0001] The present disclosure relates to an electricity storage device, for example, a cylindrical battery, a prismatic battery, or a capacitor.

[0002] A conventional energy storage device is a cylindrical battery described in Patent Document 1. In this cylindrical battery, the axial end of the electrode assembly facing the bottom of the case is formed by a negative electrode core, and this end is joined to the flat surface of a plate-shaped negative electrode current collector. The negative electrode current collector has a tongue portion that is bent into a U-shape. The tip of the bent tongue portion is joined to the bottom surface of the case. The bottom of the case also has a thin, fragile portion stamped on it.

[0003] Patent No. 7380825

[0004] In a structure in which a current collector plate is located on the bottom side of the case of the electrode body, it is easy to effectively reduce the electrical resistance of the electricity storage device, but there is a risk that the current collector plate will hinder appropriate fracture of the weak part of the case bottom. Therefore, an object of the present disclosure is to provide a highly reliable electricity storage device.

[0005] In order to solve the above problem, the present disclosure provides an energy storage device comprising: a bottomed cylindrical case having an opening and a bottom located below the opening; an electrode body disposed within the case and having a first electrode and a second electrode having a polarity different from that of the first electrode; a ring-shaped or C-shaped main body fixed to the bottom; and a current collecting plate disposed below the electrode body and having a protrusion that protrudes from the main body toward the inside of the main body and is electrically connected to the electrode body, wherein the bottom has a fixing portion to which the main body is fixed, and a fragile portion that is located more inward than the fixing portion when viewed from above and is thinner than the fixing portion, and wherein the fragile portion is located more inward than the inner periphery of the main body when viewed from above.

[0006] If the current collecting plate has a C-shaped main body, the inside of the main body is defined as the inside of the inscribed circle of the inner arc of the main body when viewed from above (if there are multiple inscribed circles, the inscribed circle with the largest area is used). Also, if the current collecting plate has a C-shaped main body, the inner periphery of the main body is defined as the inner periphery of the inscribed circle of the inner arc of the main body when viewed from above (if there are multiple inscribed circles, the inscribed circle with the largest area is used).

[0007] According to the power storage device according to the present disclosure, reliability can be easily improved.

[0008] 7 is an axial cross-sectional view of a cylindrical battery according to one embodiment of the energy storage device of the present disclosure; FIG. 8 is a perspective view showing a portion of an electrode body and a positive electrode lead; FIG. 9 is a perspective view of a negative electrode current collector plate as viewed obliquely from above; FIG. 10 is a perspective view of a negative electrode current collector plate of a first modified example, corresponding to FIG. 3; FIG. 11 is an enlarged cross-sectional view of the negative electrode current collector plate and the lower side of the case in FIG. 1; FIG. 12 is a plan view of the lower surface of the bottom of the case as viewed from the axial direction; FIG. 13 is an enlarged plan view of a peripheral region of a connection between a main body portion and a protrusion portion of a negative electrode current collector plate, viewed from above; FIG. 14 is an enlarged plan view of a negative electrode current collector of a second modified example, corresponding to FIG. 7; FIG. 15 is an enlarged plan view of a negative electrode current collector of a third modified example, corresponding to FIG. 7; FIG. 16 is an enlarged cross-sectional view of a cylindrical battery of a second modified example, corresponding to FIG. 5;

[0009] Hereinafter, an embodiment of the power storage device according to the present disclosure will be described in detail with reference to the drawings. Hereinafter, a cylindrical secondary battery using a non-aqueous electrolyte, more specifically a lithium-ion cylindrical secondary battery, will be exemplified as an embodiment of the power storage device, but the power storage device according to the present disclosure is not limited to this. The power storage device according to the present disclosure is not limited to a battery using a non-aqueous electrolyte, but may also be a battery using an aqueous electrolyte. Furthermore, the power storage device according to the present disclosure is not limited to a secondary battery, but may also be a primary battery. Furthermore, the power storage device according to the present disclosure may also be a battery other than a cylindrical battery, such as a prismatic battery. Furthermore, the power storage device according to the present disclosure may also be a capacitor (condenser) instead of a battery.

[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. Furthermore, multiple 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 axial (height) side of the sealing body 17 (the opening side of the case) is referred to as the upper side, and the axial side of the bottom 68 of the case (external can) 16 is referred to as the lower side. Furthermore, in the following description, the radial direction refers to the radial direction of the case 16, which coincides with the radial direction of the cylindrical battery 10. Furthermore, the circumferential direction refers to the circumferential direction of the case 16, which coincides with the circumferential direction of the cylindrical battery 10. Furthermore, among the components described below, components not recited in the independent claims representing the highest concepts are optional components and not required components.

[0011] 1 is an axial cross-sectional view of a cylindrical battery 10 according to an embodiment of the energy storage device of the present disclosure. As shown in Fig. 1, the cylindrical battery (hereinafter simply referred to as battery) 10 includes an electrode assembly 14, a non-aqueous electrolyte (not shown), a bottomed cylindrical case 16 that accommodates the electrode assembly 14 and the non-aqueous electrolyte, and a sealing body 17 that seals an opening 29 of the case 16 via a gasket 28.

[0012] Fig. 2 is a perspective view showing a portion of the electrode assembly 14 and the positive electrode lead 20. In Fig. 2, the positive electrode mixture layer 32 and the negative electrode mixture layer 42 are indicated by diagonal hatching. As shown in Fig. 2, the electrode assembly 14 is a wound electrode assembly having a long positive electrode 11, a long negative electrode 12, and two long separators 13, in which the positive electrode 11 and the negative electrode 12 are wound with the separator 13 interposed therebetween.

[0013] In this embodiment, the negative electrode 12 constitutes a first electrode, and the positive electrode 11 constitutes a second electrode. One or more positive electrode leads 20 are joined to the positive electrode 11, and preferably six or more positive electrode leads 20 are joined. In this embodiment, eight positive electrode leads 20 are joined to the positive electrode 11 at intervals from one another in the longitudinal direction of the positive electrode.

[0014] The negative electrode 12 is formed to be slightly larger than the positive electrode 11 in order to prevent lithium precipitation. The negative electrode 12 is formed to be longer than the positive electrode 11 in the winding direction and axial direction. Two separators 13 are formed to be 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.

[0015] A negative electrode core exposed portion, where the negative electrode mixture layer 42 is not disposed on the negative electrode core 40, is provided at the lower end in the negative electrode width direction from the winding start end to the winding end end of the negative electrode 12 in the negative electrode longitudinal direction. In this embodiment, the negative electrode core 40 is made of metal foil. The axial lower end of the electrode body 14 is made of a negative electrode core exposed portion 41. The negative electrode core exposed portion 41 is, for example, a foil portion formed of a part of the first electrode. The negative electrode 12 may form the winding start end of the electrode body 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 body 14. The negative electrode core exposed portion 41 protrudes downward below the positive electrode 11 and the separator 13.

[0016] 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

[0017] 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.).

[0018] As shown in FIG. 2 , the positive electrode 11 has a positive electrode core 30 and positive electrode mixture layers 32 formed on both sides of the positive electrode core 30. The positive electrode core 30 can be made of 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. The positive electrode mixture layer 32 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 core 30, drying the coating, and then compressing it to form the positive electrode mixture layers 32 on both sides of the positive electrode core 30.

[0019] 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.

[0020] Examples of the conductive agent contained in the positive electrode mixture layer 32 include carbon black such as acetylene black and ketjen black, and carbon materials such as graphite. Examples of the binder contained in the positive electrode mixture layer 32 include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resin, acrylic resin, and polyolefin resin. These resins may be used in combination with cellulose derivatives such as carboxymethyl cellulose (CMC) or a salt thereof, polyethylene oxide (PEO), and the like.

[0021] The positive electrode 11 has one or more positive electrode core exposed portions (not shown) where the positive electrode core is exposed, and in this embodiment, the positive electrode 11 has eight positive electrode core exposed portions arranged at intervals in the longitudinal direction of the positive electrode. Positive electrode leads 20 are joined to the positive electrode core exposed portions one by one by ultrasonic welding or the like. Effectively shortening the positive electrode side current path increases the reduction in electrical resistance, so it is preferable that the center positions of the eight positive electrode leads 20 in the longitudinal direction of the positive electrode be arranged at approximately equal intervals in the longitudinal direction of the positive electrode.

[0022] The negative electrode 12 has a negative electrode core 40 and a negative electrode mixture layer 42 formed on both sides of the negative electrode core 40. In this embodiment, the negative electrode core 40 is made of a metal foil, such as copper or a copper alloy, that is stable within the potential range of the negative electrode 12. A film having such a metal disposed on the surface layer may also be used as the negative electrode core 40. 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 a negative electrode active material and a binder to the negative electrode core 40, drying the coating, and then compressing it to form the negative electrode mixture layer 42 on both sides of the negative electrode core 40.

[0023] 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. To facilitate increased capacity, the negative electrode active material of the negative electrode mixture layer 42 preferably contains a silicon (Si) material containing silicon particles, and the mass ratio of Si element in the negative electrode mixture layer 42 is preferably 5.0 mass% or more. Furthermore, it is preferable that 3.0 mass% or more of the negative electrode mixture layer 42 be composed of silicon oxide. The negative electrode active material may also include a metal other than Si that alloys with lithium, an alloy containing such a metal, or a compound containing such a metal.

[0024] 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. The negative electrode mixture layer 42 may contain, in addition to SBR or the like, CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, or the like.

[0025] 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.

[0026] 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 a positive electrode current collector 26 and a terminal cap 27. The positive electrode current collector 26 is a metal annular plate member with a through-hole 26a in its radial center.

[0027] Terminal cap 27 is a metal plate-like member without a through hole and is located axially above sealing body 17. The axially upper end face of terminal cap 27 is exposed to the outside except for the outer edge, and this exposed portion forms the positive electrode terminal. Sealing body 17 further has a metal plate 25. Metal plate 25 is a metal annular member with a through hole.

[0028] Each positive electrode lead 20 is bent from the positive electrode 11 through the through hole 26a of the positive electrode collector plate 26 so as to fit along the upper surface of the positive electrode collector plate 26. The tip of each positive electrode lead 20 is sandwiched between the upper surface of the positive electrode collector plate 26 and the lower surface of the metal plate 25. Each positive electrode lead 20 is joined to the upper surface of the positive electrode collector plate 26. The positive electrode collector plate 26 and the metal plate 25 are also joined, and each positive electrode lead 20 and the metal plate 25 are also joined. These joints can be achieved, for example, by laser welding the tip of each positive electrode lead 20 sandwiched between the positive electrode collector plate 26 and the metal plate 25 by irradiating the metal plate 25 with a laser beam in the axial direction from above. By laser welding the tip of the positive electrode lead 20 sandwiched between the positive electrode collector plate 26 and the metal plate 25, the positive electrode lead 20 can be reliably and easily welded and joined to the positive electrode collector plate 26.

[0029] The sealing body 17 has a laminated portion 35 on its outer periphery, in which a terminal cap 27 and a positive current collector plate 26 are laminated. By irradiating the laminated portion 35 with a laser beam from above, the terminal cap 27 and the positive current collector plate 26 are laser-welded and electrically connected. The annular upper surface of the positive current collector plate 26 has an annular recess 31 radially inward from the laminated portion 35. Because the upper surface of the positive current collector plate 26 has the recess 31 recessed downward, a space is provided between the terminal cap 27 and the recess 31 of the positive current collector plate 26. Each positive electrode lead 20 is joined to the positive current collector plate 26 within the recess 31. The positive electrode collector plate 26 does not have to be joined to the metal plate 25, and the positive electrode lead 20 does not have to be joined to the metal plate 25. The battery does not have to include the metal plate 25. The positive electrode lead 20 may also be joined to the lower surface of the positive current collector plate 26.

[0030] The battery 10 has a metallic negative electrode current collector 19 axially below the electrode body 14. FIG. 3 is a perspective view of the negative electrode current collector 19 as viewed obliquely from above. As shown in FIG. 3, the negative electrode current collector 19 has an annular main body 60 and multiple protrusions (pillars) 61 that protrude from the main body 60 toward the inside of the main body 60. The multiple protrusions 61 are arranged at equal intervals in the circumferential direction. The multiple protrusions (pillars) may also be arranged at non-equidistant intervals in the circumferential direction. More specifically, the protrusions 61 protrude from the inner periphery of the main body 60 toward the inside of the main body 60.

[0031] Each protrusion 61 extends in the radial direction of the annular main body 60 (approximately the same as the radial direction of the cylindrical battery 10). The multiple protrusions 61 include a first protrusion 61a and a second protrusion 61b. When viewed from above, the extension direction of the first protrusion 61a intersects with the extension direction of the second protrusion 61b. When viewed from above, the first protrusion 61a and the second protrusion 61b do not overlap. The tip of the first protrusion 61a and the tip of the second protrusion 61b face each other. A gap is provided between the tip of the first protrusion 61a and the tip of the second protrusion 61b, so that the tips do not collide.

[0032] The main body portion may have an annular structure of any shape other than a circular ring. Furthermore, the main body portion may have, for example, a rectangular (e.g., square) annular structure in a plan view when viewed from the axial direction. Alternatively, as shown in FIG. 4 , i.e., a perspective view corresponding to FIG. 3 of the negative electrode current collector plate 119 of the first modified example, the main body portion 160 may have a C-shape with one notch 190 in a plan view when viewed from the axial direction. The protrusion (column portion) may extend in a direction intersecting the radial direction of the main body portion (approximately the radial direction of the cylindrical battery) at an acute angle. Furthermore, the negative electrode current collector plate may have only one protrusion (column portion).

[0033] As shown in FIG. 3 , the protrusion 61 is formed so as to be convex upward, and has a protruding streak 62 on its upper side. The main body 60 is located below the upper surface 65 of the protrusion 61. The protruding streak 62 is formed in the widthwise center of the protrusion 61 and protrudes upward in the thickness direction. The protruding streak 62 extends radially. A groove 63 extending radially is formed in a location on the lower surface of the protrusion 61 that overlaps the protruding streak 62 in the thickness direction. The widthwise center of the lower surface of the protrusion 61 is pressed upward in the thickness direction by a predetermined radial distance. This press working forms the protruding streak 62 and the groove 63.

[0034] The negative electrode substrate exposed portion 41 (see FIG. 2 ) is joined to the protrusion 62. Specifically, with the negative electrode substrate exposed portion 41 pressed against the protrusion 62, a laser beam is irradiated from below toward the bottom of the groove 63. This laser beam irradiates the negative electrode substrate exposed portion 41 to the protrusion 62 by laser welding over a wide radial area. In other words, the negative electrode substrate exposed portion 41 is a conductive portion that electrically connects the electrode body 14 and the current collector plate 19. Because the protrusion 61 is provided so as to be convex upward, the pressing force that presses the negative electrode substrate exposed portion 41 against the protrusion 61 can be increased, and the negative electrode substrate exposed portion 41 can be reliably welded to the protrusion 61. Furthermore, because the protrusion 61 is provided so as to be convex upward, high-temperature gas and molten material are easily guided downward along the protrusion 61 when being discharged, as described below, and the high-temperature gas and molten material can be discharged smoothly.

[0035] FIG. 5 is an enlarged cross-sectional view of the negative electrode current collector plate 19 and the lower side of the case 16 in FIG. 1 . As shown in FIG. 5 , with the lower surface of the annular main body 60 in contact with the inner surface of the bottom 68 of the case 16, laser light is irradiated from the underside of the case 16 to laser-weld the bottom 68 to the negative electrode current collector plate 19. The laser light is emitted axially from a position that overlaps the main body 60 in the axial direction. The laser light is scanned in an annular manner or intermittently scanned at intervals in the circumferential direction. By such scanning, the main body 60 is circularly welded to the bottom 68 around the entire circumferential direction, or is intermittently welded to the bottom 68 at multiple locations spaced apart in the circumferential direction. This electrically connects the negative electrode 12 of the electrode assembly 14 to the case 16 via the negative electrode current collector plate 19. By joining the negative electrode core exposed portion 41 (conductive portion) to the upper surface 65 of the negative electrode current collector plate 19 over a wide area in the longitudinal direction of the negative electrode, it is possible to prevent current from flowing long distances in the longitudinal direction of the negative electrode 12, thereby reducing the electrical resistance of the battery 10.

[0036] As shown in FIG. 1 , the case 16 has a cylindrical portion 39 and a bottom portion 68. The cylindrical portion 39 includes an annular grooved portion 22 and an annular opening (shoulder) 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 29 of the case 16 by crimping via a resin gasket 28. The opening 29 is formed when the upper end of the cylindrical portion 39 is bent radially inward and crimped to the outer edge of the sealing body 17, and extends radially inward at the upper end of the cylindrical portion 39.

[0037] The space between the case 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 case 16 and the sealing body 17, and insulates 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 and the sealing body 17.

[0038] The battery 10 further includes an annular metal plate 80 and an annular insulating plate 81 made of an insulating material. The metal plate 80 is joined to the outer surface of the axial opening side of the case 16, more specifically, to the outer surface of the opening 29. The metal plate 80 extends in a substantially radial direction. The terminal cap 27 electrically connected to the positive electrode lead 20 serves as a positive electrode terminal, and the metal plate 80 electrically connected to the negative electrode core exposed portion 41 via the negative electrode current collector plate 19 and the case 16 serves as a negative electrode terminal. The metal plate 80 is electrically connected to a current collector plate (not shown) outside the battery that connects multiple batteries 10 in series or parallel, for example, using a tongue portion (lead) of the current collector plate, and the multiple batteries 10 are electrically connected via the current collector plate. The battery 10 may be used alone.

[0039] The insulating plate 81 is interposed between the metal plate 80 and the sealing body 17 to insulate the metal plate 80 from the sealing body 17. The gasket 28 has an extension 28a at its tip end that extends radially from between the opening 29 and the sealing body 17, and the outer peripheral edge 81a on the radially outer side of the insulating plate 81 may be located above the extension 28a and in contact with the gasket 28. This ensures that the gasket 28 insulates the metal plate 80 from the sealing body 17. In this embodiment, the insulating plate 81 includes a flange portion 82 and a cylindrical portion 83 that covers the outer peripheral surface of the terminal portion 27a of the terminal cap 27 located in the radial center of the sealing body 17. The cylindrical portion 83 is connected to the radially inner end of the flange portion 82. The battery does not necessarily have to include the metal plate 80 and the insulating plate 81.

[0040] 5 , the bottom portion 68 has a fixed portion 71 to which the main body portion 60 is fixed, and a fragile portion 72 that is located inside the fixed portion 71 when viewed from above (axially) and is thinner than the fixed portion 71. When viewed from above, the fragile portion 72 is located inside the main body portion 60 and spaced apart from the main body portion 60. In this embodiment, the fragile portion 72 is configured as an annular portion that forms a closed curve in a plan view when viewed from above (axially). The bottom portion 68 includes the fragile portion 72 and a separation portion 74 that is entirely surrounded by the fragile portion 72, and has a convex portion 75 that protrudes upward.

[0041] The bottom portion 68 includes a ring portion 76 that includes the fixing portion 71 and surrounds the protruding portion 75. The upper surface of the protruding portion 75 is located higher than the upper surface of the ring portion 76, and the lower surface of the protruding portion 75 is also located higher than the lower surface of the ring portion 76. The thickness of the fragile portion 72 is thinner than the thicknesses of the fixing portion 71 and the separating portion 74. The main body portion 60 is welded to the ring portion 76. The main body portion 60 and the ring portion 76 (bottom portion 68) are electrically connected. The main body portion 60 may have an inclined portion that protrudes radially outward beyond the portion welded to the ring portion 76. The inclined portion preferably protrudes above the portion welded to the inner ring portion 76 of the main body portion 60. In other words, the inclined portion extends upward as it moves radially outward. This makes it less likely that a gap will form between the main body portion 60 and the fixing portion 71, even if the outer diameter of the main body portion 60 is increased by the amount of the inclined portion. Therefore, it is possible to suppress the generation of spatter when welding the main body 60 and the fixing part 71 (case 16), and the spatter is less likely to come into contact with the electrode body 14. Furthermore, even if the laser light during welding is irradiated with a deviation toward the outside in the radial direction, the presence of the inclined portion between the electrode body 14 and the case 16 prevents the laser light from directly damaging the electrode body 14.

[0042] FIG. 6 is a plan view of the lower surface 68a of the bottom portion 68 as viewed from the axial direction. As shown in FIG. 6, the annular weakened portion 72 has a polygonal outer edge shape in plan view as viewed from the axial direction. More specifically, in this embodiment, the outer edge shape is a square. Preferably, the annular weakened portion 72 has a regular polygonal outer edge shape. The convex portion 75 further has a thin-walled portion 78 located between the separation portion 74 and the ring portion 76. The thin-walled portion 78 is thinner than the fixing portion 71 and the separation portion 74. The thin-walled portion 78 is connected to the weakened portion 72. The thin-walled portion 78 extends in a direction from the weakened portion 72 toward the ring portion 76. The weakened portion 72 and the thin-walled portion 78 are each formed by providing a groove on the lower surface of the bottom portion 68.

[0043] More specifically, the thin-walled portion 78 is formed by grooves extending outward from each of the vertices of a polygon. This improves safety of the battery 10 while suppressing deformation of the bottom portion 68. In the example shown in Fig. 6, the thin-walled portion 78 extends outward from each vertex of the rectangular groove that constitutes the fragile portion 72. The groove shape connecting the vertices in the annular portion that constitutes the fragile portion does not have to be the straight line shown in Fig. 6 but may be a curve, and in that case, the curve preferably has an outward convex shape.

[0044] The center of the outer edge of the polygon formed by the fragile portion 72 substantially overlaps with the center C of the bottom portion 68. The depth of the groove that constitutes the fragile portion 72 is, for example, 0.1 mm or more and 0.5 mm or less, and the width of the groove that constitutes the fragile portion 72 is, for example, 0.1 mm or more and 1.0 mm or less. The cross-sectional shape of the groove that constitutes the fragile portion 72 is not particularly limited, but is, for example, V-shaped. The depth, width, and cross-sectional shape of the groove that constitutes the fragile portion 72 may vary in the stretching direction. In this case, the depth and width of the groove that constitutes the fragile portion 72 each mean the average values ​​of values ​​measured at multiple points along the stretching direction.

[0045] The depth of the groove constituting the thin-walled portion 78 is, for example, 0.1 mm to 0.7 mm, and the width of the groove constituting the thin-walled portion 78 is, for example, 0.1 mm to 1.0 mm. The cross-sectional shape of the groove constituting the thin-walled portion 78 is not particularly limited, but may be, for example, V-shaped. The depth, width, and cross-sectional shape of the groove constituting the thin-walled portion 78 may vary in the stretching direction. In this case, the depth and width of the groove constituting the thin-walled portion 78 each represent the average value of values ​​measured at multiple points along the stretching direction. The groove constituting the fragile portion 72 and the groove constituting the thin-walled portion 78 may be identical in depth, width, and cross-sectional shape, or at least one of the depth, width, and cross-sectional shape may differ. It is preferable that the thickness of the fragile portion 72 and the thin-walled portion 78 be approximately the same (approximately ±0.04 mm).

[0046] The multiple thin-walled portions 78 extend in the same rotational direction relative to the center C of the bottom portion 68. The rotational direction may be either clockwise or counterclockwise. Ends 79 of the multiple thin-walled portions 78 are located, for example, on approximately the same circumference. The end 79 is the end of the thin-walled portion 78 that is not in contact with the fragile portion 72. It is preferable that the center of the circle on which the multiple end points 79 are located approximately overlaps with the center C of the bottom portion 68.

[0047] When the battery 10 generates abnormal heat and the internal pressure of the battery continues to rise, the fragile portion 72 and at least some of the thin-walled portions 78 are preferentially broken, allowing the contents, i.e., high-temperature gas and molten material, to be expelled to the outside. This prevents the internal pressure of the battery from becoming excessively high, which could lead to battery explosion, and improves the safety of the battery 10.

[0048] In this embodiment, the battery is designed so that at least a portion of the fragile portion 72 and at least a portion of each of the thin-walled portions 78 rupture when the battery internal pressure continues to rise. This ruptures not only at least a portion of the fragile portion 72 but also at least a portion of the thin-walled portions 78, making it easier to discharge the contents to the outside. Furthermore, a large opening for discharging high-temperature gas is formed in the bottom portion 68, improving the safety of the battery 10. Each thin-walled portion 78 preferably contacts only one vertex of the polygon formed by the fragile portion 72. This makes it difficult for the separation portion 74 surrounded by the fragile portion 72 to fly away from the bottom portion 68 when the thin-walled portion 78 ruptures, making it easier for the separation portion 74 to be attached to the case 16.

[0049] 3 , when viewed from above, a first space 94 including a portion overlapping the hollow portion 14a (see FIG. 1 ) of the electrode assembly 14 and a second space 95 located between the first protrusion 61a and the second protrusion 61b are provided inside the main body 60, and the first space 94 and the second space 95 are connected to each other. Therefore, when at least a portion of the fragile portion 72 breaks, the cross-sectional area of ​​the negative electrode current collector 19 through which high-temperature gas and molten material can pass is increased, allowing the high-temperature gas and molten material to be smoothly discharged to the outside, further improving the safety of the battery 10. More specifically, the hollow portion 14a refers to a space provided in the center (axial center) of the wound electrode assembly 14. The first space 94 and the second space 95 refer to spaces provided within the case 16.

[0050] Next, some effects of the power storage device of the present disclosure that have not been mentioned so far will be described.

[0051] In contrast, the battery 10 of one embodiment according to the present disclosure has an annular or C-shaped main body 60, 160 fixed to the bottom 68, and a protrusion 61 that protrudes from the main body 60, 160 toward the inside of the main body 60, 160 and is electrically connected to the electrode body 14, and also includes a negative electrode current collector plate 19 that is disposed below the electrode body 14. Therefore, the electrode body 14 can be electrically connected to the protrusion 61 over a wide area, which shortens the current path and effectively reduces electrical resistance.

[0052] Furthermore, the bottom 68 of the case 16 has a fixed portion 71 to which the main body portion 60 is fixed, and a fragile portion 72 that is located inside the fixed portion 71 when viewed from above and is thinner than the fixed portion 71, and when viewed from above, the fragile portion 72 is located inside the inner circumference of the main body portions 60, 160.

[0053] Therefore, the annular or C-shaped main body 60, 160 is fixed to the fixing portion 71 located outside the fragile portion 72 in the bottom 68, so that the strength and rigidity of the outer portion of the bottom 68 is higher than that of the fragile portion 72, and the strength and rigidity of the fragile portion 72 is relatively lower than that of the outer portion. This makes it easier for the fragile portion 72 to rupture quickly at the set rupture pressure (expected rupture pressure) of the battery 10.

[0054] Therefore, the battery 10 of the present disclosure can easily achieve both an effective reduction in electrical resistance and high safety, which means that the reliability of the battery can be improved.

[0055] The bottom 68 includes a fragile portion 72 and a separation portion 74 completely surrounded by the fragile portion 72, and has a protrusion 75 that protrudes upward, and a ring portion 76 that includes the fixing portion 71 and surrounds the protrusion 75. The main body 60 is welded to the ring portion 76. Therefore, high-temperature gas and molten material are likely to reach the fragile portion 72 before the ring portion 76, which is reinforced by the main body 60 of the negative electrode current collector plate. This makes the fragile portion 72 more likely to break, and the contents are more likely to be discharged.

[0056] 1, when viewed from above, the tip of the protruding portion 61 is located inside the fragile portion 72 and overlaps with the separation portion 74. Therefore, pressure from the contents is more likely to be applied inside the fragile portion 72, which makes it easier for a large load to be applied to the separation portion 74, making it easier for the separation portion 74 to separate smoothly.

[0057] Furthermore, the main body 60 is positioned below the upper surface 65 of the protrusion 61. The main body 60 is welded to the ring portion 76 around the entire circumference, or is welded to the ring portion 76 intermittently at intervals in the circumferential direction. This further increases the fixing strength between the negative electrode current collector plate 19 and the ring portion 76 located on the outer periphery of the bottom 68. This further reduces the relative strength of the fragile portion 72 with respect to the ring portion 76, making it easier to break the fragile portion 72.

[0058] The present disclosure is not limited to the above-described embodiment and its modifications. Various improvements and modifications are possible within the scope of the claims and their equivalents. For example, in the above-described embodiment, as shown in FIG. 7 , an enlarged plan view of the area surrounding the connection between the main body 60 and the protrusion 61 of the negative current collector plate 19 viewed from above, the main body 60 and the protrusion 61 are connected via a corner having a substantially L-shaped outer edge 97. However, as shown in FIG. 8 , an enlarged plan view of a negative current collector plate 219 of a second modification corresponding to FIG. 7 , the main body 260 may be provided with a pair of recesses 239 recessed from the inside to the outside of the main body 260. The protrusion 261 may be disposed between the pair of recesses 239.

[0059] Providing such a pair of recesses 239 in the negative electrode current collector plate 219 makes it easier for the main body 260 to deform. Therefore, it becomes easier to bring the lower surface of the main body 260 into clean contact with the bottom 68 of the case 16, and welding of the main body 260 and the bottom 68 can be performed smoothly and accurately. Furthermore, the presence of the pair of recesses 239 makes it easier for the protrusion 261 to deform. Therefore, when the protrusion 262 of the protrusion 261 is formed by press molding, the press molding can be performed with high precision, and the protrusion 262 can be formed with high precision.

[0060] 9, that is, an enlarged plan view of a negative electrode current collector plate 319 of a third modified example corresponding to FIG. 7, a plurality of recesses 380 may be provided on both side surfaces 351, 352 of a protruding portion (pillar portion) 361. In this case, both side surfaces 351, 352 of a main body portion 360 may have a wave shape in a plan view when viewed from above.

[0061] Providing such a plurality of recesses 380 in negative electrode current collector plate 319 makes it difficult for the contents to form clumps when they are discharged. Therefore, the contents are less likely to get caught in the opening that is opened when either or both of fragile portion 72 and thin-walled portion 78 at the bottom of the case are broken, making it easier to discharge the contents to the outside smoothly, further increasing safety.

[0062] 10 , an enlarged cross-sectional view of a cylindrical battery 410 according to a second modification, corresponding to FIG. 5 , a metal reinforcing member 488 may be disposed between the main body 60 of the negative electrode current collector 19 and the fixed portion 71 of the case 16 in the height direction. The reinforcing member 488 may be configured as a single member having an annular or C-shaped configuration in plan view when viewed from above. Alternatively, the reinforcing member 488 may be configured as a plurality of arc-shaped members each having an arc shape in plan view when viewed from above. In this case, the plurality of arc-shaped members may be arranged, for example, on concentric circles at intervals in the circumferential direction.

[0063] According to the cylindrical battery 410 of the second modification, the strength (rigidity) of the fixed portion 71 can be increased by fixing the negative electrode current collector plate 19 to the fixed portion 71. More specifically, the fixed portion 71 is less likely to deform. Therefore, the relative strength of the fragile portion 72 compared to the fixed portion 71 can be effectively reduced, making it easier to break the fragile portion 72. Instead of disposing the reinforcing member 488 between the main body 60 and the fixed portion 71, the thickness of the fixed portion to which the main body is fixed at the bottom of the case may be made thicker than the maximum thickness at the center of the bottom (e.g., the maximum thickness of the separation portion). In this case, for example, the maximum thickness of the ring portion that includes the fixed portion and surrounds the convex portion may be made thicker than the thickness of the convex portion. This also effectively reduces the relative strength of the fragile portion compared to the fixed portion, making it easier to break the fragile portion. The reinforcing member 488 may be fixed to the upper surface of the main body 60. In other words, the main body 60 may be disposed between the reinforcing member 488 and the fixed portion 71. By disposing the main body 60 between the reinforcing member 488 and the fixing part 71, it becomes difficult for metal debris to be scattered inside the can when the main body 60 and the fixing part 71 are welded together. Since it is possible to prevent metal debris from being generated inside the battery 10, it becomes difficult for the voltage of the battery 10 to drop unintentionally.

[0064] In the above description, the bottom 68 of the case 16 has a ring portion 76 that includes the fixing portion 71 and surrounds the protrusion 75. However, the bottom of the case does not have to have a protrusion. Also, in the above description, the protrusion 61 is formed to be convex upward and has a protrusion 62 on the upper side. Also, in the above description, a groove 63 extending radially is provided on the lower surface of the protrusion 61 at a location that overlaps the protrusion 62 in the thickness direction. However, the protrusion 61 may be formed to be convex upward and have a protrusion on the upper side, but no groove may be provided on the lower surface of the protrusion. Furthermore, the thickness of the protrusion may be thicker than the thickness of the portion of the protrusion where no protrusion is present.

[0065] In the above description, the fragile portion 72 has a polygonal outer edge shape in a plan view from the axial direction. However, the fragile portion may have a circular or C-shape when viewed from the axial direction (plan view), and may be provided by, for example, stamping a circle or a C-shape on the underside of the bottom of the case. Also, although the fragile portion is provided by providing a groove on the underside of the bottom of the case, the fragile portion may be provided by providing a groove on the upper side of the bottom of the case.

[0066] In the above description, the conductive portion electrically connecting the electrode body 14 and the negative electrode current collector plate 19 is the negative electrode core exposed portion 41 that constitutes the lower end of the electrode body 14. However, when the negative electrode has a strip shape, the conductive portion electrically connecting the electrode body and the negative electrode current collector plate may be a plurality of negative electrode leads spaced apart in the longitudinal direction of the negative electrode, one end of which is joined to the negative electrode. Alternatively, the other end of each negative electrode lead may be joined to the upper surface of the negative electrode current collector plate.

[0067] In the above description, the positive electrode 11 is electrically connected to the sealing body 17 via one or more positive electrode leads 20. However, the upper end of the electrode body may be configured as a positive electrode substrate exposed portion, and the positive electrode substrate exposed portion may be joined to the positive electrode current collector plate by welding or the like. The positive electrode current collector plate may then be electrically connected to a conductive member that includes the upper surface of the sealing body and has conductivity, thereby electrically connecting the positive electrode to the upper surface of the sealing body.

[0068] The case where the negative electrode 12 constitutes the first electrode and the positive electrode 11 constitutes the second electrode has been described, and the case where the case 16 is electrically connected to the negative electrode 12 and the negative electrode current collector 19 is disposed on the bottom 68 side of the case 16 in the electrode body 14 has been described. However, the positive electrode may constitute the first electrode and the negative electrode may constitute the second electrode, or the case may be electrically connected to the positive electrode and the positive electrode current collector may be disposed on the bottom side of the case in the electrode body.

[0069] In addition, the case where the sealing body 17 does not have a rupture plate that ruptures when the pressure inside the battery reaches a set pressure and temperature has been described. However, the sealing body may also have two rupture plates (a lower valve body and an upper valve body) and a convex terminal cap that covers the rupture plate. Alternatively, the sealing body may be composed of only a rupture plate. Alternatively, the sealing body may have a structure in which, from the electrode body side, an internal terminal plate, an insulating plate, and a rupture plate are stacked.

[0070] The power storage device of the present disclosure may also have the following configurations: Configuration 1: A bottomed cylindrical case (16) having an opening (29) and a bottom (68) located below the opening (29), an electrode body (14) disposed within the case (16) and having a first electrode (12) and a second electrode (11) having a polarity different from that of the first electrode (12), an annular or C-shaped main body (60, 160, 260, 460) fixed to the bottom (68), and a capacitor (60, 160, 260, 460) protruding from the main body (60, 160, 260, 460) toward the inside of the main body (60, 160, 260, 460) and electrically connected to the electrode body (14). a current collecting plate (19, 119, 219, 319) disposed below the electrode body (14), and a protrusion (61, 261, 361) that is fixed to the bottom (68) of the battery; and a current collecting plate (19, 119, 219, 319) that is disposed below the electrode body (14), the bottom (68) having a fixing portion (71) to which the main body portion (60, 160, 260, 460) is fixed, and a fragile portion (72) that is located inside the fixing portion (71) when viewed from above and is thinner than the fixing portion (71), and the fragile portion (72) is located inside the inner periphery of the main body portion (60, 160, 260, 460) when viewed from above. Configuration 2: The electric storage device (10, 410) according to Configuration 1, wherein the protrusion (61, 261, 361) is provided so as to be convex upward, the electrode body (14) is a wound electrode body in which the first electrode (12) and the second electrode (11) are wound with a separator (13) interposed therebetween, the electrode body (14) has a conductive part that electrically connects the electrode body (14) and the current collector plate (19, 119, 219, 319), the conductive part is a protrusion that protrudes from below the electrode body (14) or constitutes a lower end of the electrode body (14), and the conductive part (41) is joined to the protrusion (61, 261, 361) of the current collector plate (19, 119, 219, 319). Configuration 3: The storage device (10, 410) according to configuration 2, wherein the conductive portion (41) is a foil portion that constitutes the lower end of the electrode body (14) and is part of the first electrode (11).Configuration 4: The energy storage device (10, 410) according to any one of configurations 1 to 3, wherein the bottom portion (68) includes the fragile portion (72) and a separation portion (74) completely surrounded by the fragile portion (72), and has a convex portion (75) protruding upward, and a ring portion (76) that includes the fixing portion (71) and surrounds the convex portion (75), the thickness of the fragile portion (72) is thinner than the thicknesses of the fixing portion (71) and the separation portion (74), and the main body portion (60, 160, 260, 460) is welded to the ring portion (76). The present invention relates to an electric storage device (10, 410) and a power storage device (10, 410) for a power storage device (10, 410) according to any one of the preceding configurations, wherein the protrusion (75) further includes a thin-walled portion (78) located between the separation portion (74) and the ring portion (76), the thin-walled portion (78) being thinner than the thicknesses of the fixing portion (71) and the separation portion (74), the thin-walled portion (78) being connected to the fragile portion (72), and the thin-walled portion (78) extending in a direction from the fragile portion (72) toward the ring portion (76). Configuration 7: The current collecting plate (19, 119, 219, 319) has a first protrusion (61 a) that is the protrusion (61, 261, 361), and a second protrusion (61 b) that protrudes from the main body portion (60, 160, 260, 460) toward the inside of the main body portion (60, 160, 260, 460), and is arranged so that an extension direction of the extension direction of the first protrusion (61 a) and an extension direction of the extension direction of the second protrusion (61 b) intersect with each other when viewed from above, a tip of the second protrusion (61 b) is located inside the fragile portion (72) when viewed from above, a tip of the second protrusion (61 b) overlaps with the separation portion (74), and the second protrusion (61 b) and the first protrusion (61 a) do not overlap. Configuration 8: The energy storage device according to any one of configurations 1 to 7, wherein the main body portion (260) is provided with a pair of recesses (239) recessed in a direction from the inside of the main body portion (260) toward the outside of the main body portion (260), and the protrusion (260) is disposed between the pair of recesses (239).Configuration 9: The electric storage device (10) according to any one of configurations 1 to 8, wherein the main body portion (60, 160, 260, 460) is welded to the annular portion (76) around the entire circumference or intermittently welded to the annular portion (76) at intervals in the circumferential direction.Configuration 10: The electric storage device (10) according to any one of configurations 1 to 9, wherein the protrusion (361) of the current collecting plate (319) has a plurality of depressions (380) formed on a side surface (351, 352). Configuration 11: The electrode body (14) is a wound electrode body in which the first electrode (11) and the second electrode (12) are wound with a separator (13) interposed therebetween, and the current collector plate (19, 119, 219, 319) has a first protruding portion (61a) which is the protruding portion (61, 261, 361) and a second protruding portion (61b) which protrudes from the main body portion (60, 160, 260, 460) toward the inside of the main body portion (60, 160, 260, 460), and when viewed from above, , 160, 260, 460), a first space (94) including a portion overlapping the hollow portion (14a) of the electrode body (14) and located between the tip of the first protrusion (61a) and the tip of the second protrusion (61b), and a second space (95) located between the side of the first protrusion (61a) and the side of the second protrusion (61b) are provided inside the storage device (10, 410) described in configuration 1, and the first space (94) and the second space (95) are connected to each other.

[0071] 10,410 Battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 14a Hollow portion, 16 Case, 17 Sealing body, 18 Insulating plate, 19,119,219,319 Negative electrode current collector plate, 20 Positive electrode lead, 22 Grooved portion, 25 Metal plate, 26 Positive electrode current collector plate, 26a Through hole, 27 Terminal cap, 27a Terminal portion, 28 Gasket, 28a Extension portion of gasket, 29 Opening, 30 Positive electrode core, 31 Recess, 32 Positive electrode mixture layer, 35 Laminated portion, 39 Cylindrical portion, 40 Negative electrode core, 41 Negative electrode core exposed portion, 42 Negative electrode mixture layer 60, 160, 260, 460 Main body portion, 61, 261, 361 Protruding portion, 61a First protruding portion, 61b Second protruding portion, 62 Ridge portion, 63 Groove portion, 65 Upper surface of protruding portion, 68 Bottom portion, 68a Lower surface, 71 Fixing portion, 72 Weak portion, 74 Separation portion, 75 Convex portion, 76 Ring portion, 78 Thin portion, 79 End portion, 80 Metal plate, 81 Insulating plate, 81a Outer peripheral edge portion, 82 Flange portion, 83 Cylindrical portion, 94 First space, 95 Second space, 97 Outer edge, 190 Notch, 239 Recess, 262 Ridge portion, 351, 352 Side surface of protruding portion, 380 Indentation, 488 Reinforcing member.

Claims

1. An energy storage device comprising: a cylindrical case with a bottom having an opening and a bottom located below the opening; an electrode body disposed within the case and having a first electrode and a second electrode having a polarity different from that of the first electrode; a ring-shaped or C-shaped main body fixed to the bottom; and a current collecting plate disposed below the electrode body, the current collecting plate having a protrusion that protrudes from the main body toward the inside of the main body and is electrically connected to the electrode body, wherein the bottom has: a fixing portion to which the main body is fixed; and a fragile portion that is located inside the fixing portion when viewed from above and is thinner than the fixing portion, and wherein the fragile portion is located inside the inner circumference of the main body when viewed from above.

2. The energy storage device according to claim 1, wherein the protrusion is provided so as to be convex upward, the electrode body is a wound electrode body in which the first electrode and the second electrode are wound with a separator interposed therebetween, the electrode body has a conductive part that electrically connects the electrode body and the current collector plate, the conductive part being a protrusion that protrudes from below the electrode body, or constituting a lower end of the electrode body, and the conductive part being joined to the protrusion of the current collector plate.

3. The electricity storage device according to claim 2, wherein the conductive portion is a foil portion that constitutes the lower end portion of the electrode body and is part of the first electrode.

4. A storage device as described in any one of claims 1 to 3, wherein the bottom portion has a convex portion that includes the weak portion and a separation portion that is completely surrounded by the weak portion and that protrudes upward, and a ring portion that includes the fixing portion and surrounds the convex portion, the thickness of the weak portion being thinner than the thicknesses of the fixing portion and the separation portion, and the main body portion is welded to the ring portion.

5. A storage device according to any one of claims 1 to 3, wherein the convex portion further has a thin-walled portion located between the separation portion and the ring portion, the thickness of the thin-walled portion being thinner than the thicknesses of the fixing portion and the separation portion, the thin-walled portion being connected to the weak portion, and the thin-walled portion extending in a direction from the weak portion toward the ring portion.

6. The electricity storage device according to any one of claims 1 to 3, wherein, when viewed from above, the tip of the protruding portion of the current collector plate is located inside the weak portion and overlaps with the separation portion.

7. The energy storage device according to claim 6, wherein the current collecting plate has a first protrusion which is the protrusion, and a second protrusion which protrudes from the main body portion to the inside of the main body portion, and when viewed from above, the extension direction of the extension direction of the first protrusion and the extension direction of the second protrusion are arranged so as to intersect, when viewed from above, the tip of the second protrusion is located inside the weak portion, the tip of the second protrusion overlaps the separation portion, and the second protrusion and the first protrusion do not overlap.

8. The energy storage device according to any one of claims 1 to 3, wherein the main body portion is provided with a pair of recesses recessed in a direction from the inside of the main body portion toward the outside of the main body portion, and the protrusion portion is disposed between the pair of recesses.

9. The electricity storage device according to any one of claims 1 to 3, wherein the main body is welded to the ring portion along the entire circumference, or is welded to the ring portion intermittently at intervals in the circumferential direction.

10. The electricity storage device according to any one of claims 1 to 3, wherein the protruding portion of the current collector plate has a plurality of recesses formed on a side surface thereof.

11. The energy storage device according to claim 1, wherein the electrode body is a wound electrode body in which the first electrode and the second electrode are wound with a separator interposed therebetween, the current collector plate has a first protrusion which is the protrusion, and a second protrusion which protrudes from the main body portion to the inside of the main body portion, and when viewed from above, the inside of the main body portion includes a portion which overlaps with the hollow portion of the electrode body, and is provided with a first space located between the tip of the first protrusion and the tip of the second protrusion, and a second space located between the side surface of the first protrusion and the side surface of the second protrusion, and the first space and the second space are connected to each other.

Images