Power storage device

Abstract

This power storage device comprises: a case (15) that has an opening; an electrode body that is disposed inside the case (15); a sealing body that is disposed above the electrode body and closes the opening of the case (15); and a conductive member (20) that electrically connects the electrode body and the sealing body (17). The sealing body (17) is provided with a through hole (25) penetrating in the vertical direction, the through hole (25) overlaps the conductive member (20) when viewed from above, and a protrusion (27) overlapping the conductive member (20) when viewed from above is provided on the lower surface of the sealing body (17). One end of the conductive member (20) is connected to the electrode body, and the other end is joined to the electrode body-side surface of the sealing body (17).

Description

Power storage device

[0001] The present disclosure relates to a power storage device, and particularly to the structure of a sealing body of the power storage device.

[0002] A power storage device generally includes an electrode body, a case that houses the electrode body, and a sealing body that closes an opening of the case, and has a conductive member that electrically connects the electrode body and the sealing body (for example, Patent Document 1). In addition, a plugging structure may be adopted to shorten the time of the electrolyte injection process. The plugging structure is formed by sealing the opening of the case with a sealing body having an electrolyte injection port, venting the air in the case from the electrolyte injection port, injecting the electrolyte from the electrolyte injection port, and then sealing the electrolyte injection port.

[0003] Japanese Patent Application Laid-Open No. 9-320562

[0004] In a power storage device having a plugging structure, when venting air from the electrolyte injection port, a conductive member located between the sealing body and the electrode body is attracted to the electrolyte injection port and adheres to the surface of the sealing body on the electrode body side, thereby blocking the electrolyte injection port. As a result, the amount of the electrolyte to be injected does not reach the specified amount, resulting in a manufacturing defect. Thereby, there is a problem that the reliability of the power storage device is reduced. Note that the power storage device according to the prior document 1 cannot solve such a problem either.

[0005] The power storage device according to the present disclosure includes a case having an opening, an electrode body disposed in the case, a sealing body disposed above the electrode body and closing the opening of the case, and a conductive member that electrically connects the electrode body and the sealing body. The sealing body is provided with a through hole penetrating in the vertical direction. The through hole overlaps with the conductive member when viewed from above. A convex portion that overlaps with the conductive member when viewed from above is provided on the lower surface of the sealing body. One end of the conductive member is connected to the electrode body, and the other end is joined to a position on the surface of the sealing body on the electrode body side where the convex portion is not provided.

[0006] According to the power storage device according to the present disclosure, a more reliable power storage device can be provided.

[0007] This is an axial cross-sectional view of the energy storage device according to this embodiment. This is an enlarged view of part A in Figure 1. This is a diagram showing the structure of the sealing body according to the first embodiment. This is a diagram showing the structure of the sealing body according to the second embodiment. This is a diagram showing the structure of the sealing body according to the third embodiment. This is a diagram showing the structure of the sealing body according to the fourth embodiment. This is a diagram showing another example of the plan view shape of the convex portion.

[0008] Hereinafter, an example of an embodiment of the energy storage device according to this disclosure will be described in detail with reference to the drawings. Note that configurations obtained by selectively combining the various components of the multiple embodiments and modified examples described below are included within the scope of this disclosure.

[0009] In the following, a cylindrical secondary battery using a non-aqueous electrolyte, more specifically a lithium-ion cylindrical secondary battery, is given as an example of an 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 is not limited to a battery, but may also be a capacitor.

[0010] A cylindrical battery 10, which is an example of an embodiment, will be described in detail with reference to Figures 1 and 2. Figure 1 is a cross-sectional view of a cylindrical battery 10, which is an example of an embodiment. Figure 2 is an enlarged view of part A in Figure 1, which shows the sealing body 17 of the cylindrical battery 10 in detail. As shown in Figure 1, the cylindrical battery 10 comprises a wound electrode body 14, a bottomed cylindrical case 15 that houses the electrode body 14, and a sealing body 17 that is positioned above the electrode body 14 and closes the opening of the case 15. The cylindrical battery 10 contains an electrolyte, and the electrolyte is housed in the case 15 together with the electrode body 14. As will be described in more detail later, the sealing body 17 has a through hole 25 that penetrates in the vertical direction and connects the internal space and the external space of the case 15.

[0011] In this specification, "plan view" means a view of the bottomed cylindrical case 15 from the axial direction. The plan view may be in the axial direction of the case 15 and may be a view from the electrode body 14 side or a view from the opening side of the case 15. In this specification, the vertical direction is defined as the direction from the electrode body 14 toward the seal body 17 and the direction from the seal body 17 toward the electrode body 14, when the sealing body 17 and the electrode body 14 are arranged from top to bottom in that order.

[0012] The electrode body 14 has a positive electrode 11, a negative electrode 12, and a separator 13, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound in a spiral shape via the separator 13. The positive electrode 11, the negative electrode 12, and the separator 13 are all elongated strip-shaped bodies, and are alternately stacked in the radial direction of the electrode body 14 by being wound in a spiral shape. The negative electrode 12 is formed to be slightly larger in dimensions than the positive electrode 11 in order to prevent lithium deposition. That is, the negative electrode 12 is formed to be longer in the longitudinal direction and the width direction (short direction) than the positive electrode 11. The separator 13 is formed to be at least slightly larger in dimensions than the positive electrode 11, and two separators are arranged so as to sandwich the positive electrode 11.

[0013] The case 15 is a bottomed cylindrical metal container that houses the electrode body 14 and the electrolyte. A groove 16 is formed on the side of the case 15, extending circumferentially and protruding radially inward. The radial length of the groove 16 on the case 15 is preferably such that it does not come into contact with the positive electrode lead 20 extending from the electrode body 14. For the sake of explanation, the side of the cylindrical battery 10 with the sealing body 17 will be considered the top, and the bottom side of the case 15 will be considered the bottom. The groove 16 is preferably formed in an annular shape along the circumferential direction of the case 15, and its upper surface supports the sealing body 17. The sealing body 17 and gasket 30 are fixed to the top of the case 15 by the groove 16 and the open end of the case 15 that is crimped to the sealing body 17 and gasket 30. The opening of the case 15 is circular in plan view, and the sealing body 17 is similarly circular in plan view.

[0014] The electrolyte may be an aqueous electrolyte, but in this embodiment, a non-aqueous electrolyte is used. The non-aqueous electrolyte has lithium-ion conductivity. The non-aqueous electrolyte may be a liquid electrolyte (electrolyte solution) or a solid electrolyte. The cylindrical battery 10 is a non-aqueous electrolyte secondary battery, and among these, a lithium-ion battery is preferred.

[0015] A liquid electrolyte (electrolyte solution) comprises a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of non-aqueous solvents include esters, ethers, nitriles, amides, and mixtures of two or more of these. Examples of non-aqueous solvents include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixtures thereof. The non-aqueous solvent may also contain halogen-substituted solvents (e.g., fluoroethylene carbonate) in which at least some of the hydrogen atoms in the solvent are replaced with halogen atoms such as fluorine. Examples of electrolyte salts include LiPF4. ６ Lithium salts such as these are used.

[0016] As the solid electrolyte, for example, a solid or gel-like polymer electrolyte, an inorganic solid electrolyte, etc., can be used. As the inorganic solid electrolyte, materials known for all-solid-state lithium-ion secondary batteries, etc. (for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, halogen-based solid electrolytes, etc.) can be used. The polymer electrolyte includes, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt and a matrix polymer. As the matrix polymer, for example, a polymer material that absorbs a non-aqueous solvent and gels is used. Examples of polymer materials include fluororesins, acrylic resins, polyethers, etc.

[0017] The positive electrode 11 has a long positive electrode core and positive electrode mixture layers formed on both sides of the positive electrode core. The positive electrode core can be made of a metal foil that is stable within the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film with the metal arranged on its surface. The positive electrode mixture layers contain 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 core, drying the coating, and then compressing it to form positive electrode mixture layers on both sides of the positive electrode core.

[0018] The positive electrode active material is mainly composed of a lithium-containing metal composite oxide. Examples of metal elements contained in the lithium-containing metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, and W. A preferred example of a lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0019] Examples of conductive agents included in the positive electrode mixture layer include acetylene black (AB), carbon black such as Ketjenblack, graphite, carbon nanotubes (CNTs), carbon nanofibers, graphene, metal fibers, metal powders, and conductive whiskers. 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.

[0020] The negative electrode 12 comprises a negative electrode core and a negative electrode mixture layer formed on both sides of the negative electrode core. In this embodiment, the negative electrode core is made of a metal foil that is stable within the potential range of the negative electrode 12, such as copper or a copper alloy. A film with the metal arranged on its surface may also be used as the negative electrode core. 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 a negative electrode active material and a binder onto the negative electrode core, drying the coating, and then compressing it to form the negative electrode mixture layer on both sides of the negative electrode core.

[0021] Generally, carbon materials that reversibly intercalate and release lithium ions are used as the negative electrode active material. Preferred carbon materials are graphites 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. Since it is easy to increase the capacity, it is preferable that the negative electrode active material of the negative electrode mixture layer contains a Si material containing silicon (Si) particles, and it is preferable that the mass ratio of Si elements in the negative electrode mixture layer is 5.0% by mass or more. It is also preferable that 3.0% by mass or more of the negative electrode mixture layer is composed of silicon oxide. Other metals that alloy with lithium besides Si, alloys containing such metals, compounds containing such metals, etc., may also be used as the negative electrode active material.

[0022] 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 CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, etc.

[0023] The separator 13 is made of a porous sheet having ion permeability and insulating properties. Specific examples of porous sheets include microporous thin films, woven fabrics, and nonwoven fabrics. Suitable materials for the separator 13 (porous sheet) include polyethylene, polyolefins such as polypropylene, and cellulose. The separator 13 may have a single-layer structure or a multi-layer structure. In addition, a highly heat-resistant resin layer, such as aramid resin, may be formed on the surface of the separator 13.

[0024] The electrode body 14 further includes a positive electrode lead 20 that functions as a conductive member to electrically connect the positive electrode 11 of the electrode body 14 to the sealing body 17, and a negative electrode lead 21 that electrically connects the negative electrode 12 to the case 15. One end of the positive electrode lead 20 is connected to the core of the positive electrode 11 by welding or the like, and the other end is connected to the lower surface of the sealing body 17 by welding or the like, so that the sealing body 17 becomes the positive electrode external terminal. One end of the negative electrode lead 21 is connected to the core of the negative electrode 12, and the other end is connected to the inner surface of the bottom of the case 15 by welding or the like, so that the case 15 becomes the negative electrode external terminal. In addition, an upper insulating plate 22 and a lower insulating plate 23 are arranged above and below the electrode body 14, respectively. The upper insulating plate 22 is provided between the electrode body 14 and the sealing body 17, and the lower insulating plate 23 is provided between the electrode body 14 and the bottom of the case 15. In the example shown in Figure 1, the positive lead 20 extends through the through-hole in the upper insulating plate 22 towards the sealing body 17, and the negative lead 21 extends outside the lower insulating plate 23 towards the bottom of the case 15.

[0025] As described above, one end of the positive electrode lead 20 is connected to the electrode body 14, and the other end is connected to the lower surface of the sealing body 17. Also, as shown in Figure 2, the positive electrode lead 20 extending from the electrode body 14 is folded back between the one end and the other end. That is, a folded portion 20a is formed between the one end and the other end. In the following, the area of ​​the positive electrode lead 20 on the one end side of the folded portion 20a will be described as the one-end side region 20b, and the area on the other end side of the folded portion 20a will be described as the other-end side region 20c. Furthermore, when the positive electrode lead 20 is viewed from the sealing body 17 side in the axial direction of the electrode body 14, the one-end side region 20b that does not overlap with the other-end side region 20c will be described as the reference region 20d.

[0026] Case 15 is a bottomed cylindrical metal container with one end open in the axial direction, and the opening of case 15 is sealed by a sealing body 17 via a gasket 30. The constituent material of case 15 is not particularly limited, but examples of preferred constituent materials include carbon steel and stainless steel.

[0027] As shown in Figures 1 and 2, the sealing body 17 is provided with a through hole 25 that connects the internal space and the external space of the case 15. In this embodiment, the sealing body 17 has a sealing plate 24 with a through hole 25. The sealing body 17 also has a lid 26 for closing the through hole 25 of the sealing plate 24.

[0028] The sealing plate 24 has a circular shape in plan view. The sealing plate 24 can be manufactured, for example, by press-forming a sheet of aluminum or an aluminum alloy. Aluminum and aluminum alloys are preferred materials for the sealing plate 24, which functions as an explosion-proof valve, because they have excellent flexibility.

[0029] The sealing plate 24 has, for example, a through hole 25 in its central portion 24a. The through hole 25 has, for example, a circular shape in plan view. The plan view shape of the through hole 25 is not particularly limited. The through hole 25 is formed so as to overlap with the positive electrode lead 20 when viewed from above. More specifically, the through hole 25 is formed so as to overlap with the reference region 20d of the positive electrode lead 20 when viewed from above. It is also preferable that the entire through hole 25 overlaps with the reference region 20d of the positive electrode lead 20. More specifically, it is preferable that the diameter of the through hole 25 is smaller than the width of the positive electrode lead 20. The diameter of the through hole 25 is, for example, 2.0 mm.

[0030] The through-holes 25 are preferably arranged in steps, as shown in Figures 1 and 2. That is, the sealing plate 24 is preferably shaped like steps around the through-holes 25. With this, the tip of the nozzle used when removing air from inside the case 15 and when injecting electrolyte into the case 15 can be placed against the second step 25b. This improves the efficiency of exhaust and injection. Here, in this specification, exhaust means removing air from inside the case 15. Injection means injecting electrolyte into the case 15.

[0031] The lid 26 has a flange portion and a projection that protrudes downward from the flange portion. The flange portion of the lid 26 and the sealing plate 24 are welded together. The first stage 25a is formed in a circular shape in plan view and has a diameter larger than the diameter of the lid 26. Furthermore, the depth of the first stage 25a is formed to be greater than the thickness of the flange portion of the lid 26. This makes it difficult for the lid 26 to protrude upward relative to the sealing plate 24.

[0032] The material of the lid 26 is not particularly limited, but it may be made of the same material as the sealing plate 24. The shape of the lid 26 is preferably, for example, circular in plan view and having a protruding portion that extends from the center. With this, the lid 26 is less likely to shift position when the protruding portion is inserted into the through hole 25. It is preferable that the length of the protruding portion is such that it does not extend beyond the lower surface of the sealing plate 24.

[0033] The sealing plate 24 has a central portion 24a in which a through hole 25 is provided, an outer peripheral portion 24b extending radially outward from the central portion 24a to the case 15, and a thin-walled portion 24c connecting the central portion 24a and the outer peripheral portion 24b.

[0034] The thickness of the thin-walled portion 24c is thinner than that of the central portion 24a and the outer peripheral portion 24b. The lower surface of the thin-walled portion 24c is located above the lower surface of the central portion 24a and is connected to the lower surface of the central portion 24a via an annular groove 24d. The annular upper surface of the thin-walled portion 24c is an inclined surface that is located upward as it moves radially outward, and the annular lower surface of the thin-walled portion 24c is also an inclined surface that is located upward as it moves radially outward. The thickness of the thin-walled portion 24c decreases as it moves radially outward.

[0035] With the above configuration of the sealing plate 24, when the internal pressure of the cylindrical battery 10 reaches a predetermined value, gas can be released. Specifically, when the internal pressure of the cylindrical battery 10 reaches a predetermined value, the central part 24a and the thin-walled part 24c of the sealing plate 24 invert upward in the height direction, using the radially outward annular end 24e, which has low rigidity in the thin-walled part 24c, as a fulcrum. Furthermore, as the internal pressure rises, the annular end 24e of the thin-walled part 24c ruptures, and the gas inside the battery is discharged to the outside from the rupture in the sealing plate 24. This prevents the battery from rupturing even when the internal pressure of the cylindrical battery 10 rises.

[0036] Although not shown in Figure 2, the sealing body 17 may also have a structure in which multiple components such as an internal terminal plate and an annular insulating plate are stacked in order from the electrode body 14 side. Each component constituting the sealing body 17 has a disc shape or a ring shape, and each component except the annular insulating plate is electrically connected. In this case, the positive electrode lead 20 is connected to the lower surface of the internal terminal plate, which is the electrode body 14 side of the sealing body 17.

[0037] As shown in Figures 1 and 2, the gasket 30 is a sealing member positioned on the opening side of the case 15, between the sealing body 17 and the case 15. The annular gasket 30 seals the space between the case 15 and the sealing body 17, thereby sealing the internal space of the case 15. The gasket 30 also insulates the sealing body 17 from the case 15. In other words, the gasket 30 serves as a sealing material to maintain airtightness inside the battery and as an insulating material to prevent short circuits between the case 15 and the sealing body 17.

[0038] The gasket 30 is fixed to the upper end of the case 15 by the grooved portion 16 of the case 15 and the crimped portion 18 of the opening edge of the case 15 which is crimped to the sealing body 17 and the gasket 30. After crimping and fixing, the gasket 30 is positioned between the sealing body 17 and the crimped portion 18, and between the sealing body 17 and the grooved portion 16.

[0039] The sealing body 17 according to the first embodiment will be described in detail with further reference to Figure 3. Figure 3 is a schematic diagram of the sealing body 17 as viewed from the electrode body 14 side. For clarity of the drawing, the case 15 and gasket 30 are omitted. Also, for explanatory purposes, each region of the positive electrode lead 20 is shown. The reference region 20d is included in the one-end side region 20b, but in Figure 3, for explanatory purposes, the reference region 20d is shown with low-density dots, and the one-end side region 20b other than the reference region 20d is shown with high-density dots. The other-end side region 20c is hidden by the one-end side region 20b and is therefore not shown with dots.

[0040] As shown in Figures 2 and 3, a protrusion 27 is provided on the lower surface of the sealing body 17, projecting toward the electrode body 14. More specifically, the protrusion 27 is provided on the lower surface of the sealing body 17 so as to overlap with the positive electrode lead 20, which is a conductive member, when viewed from above. That is, the protrusion 27 is formed so as to overlap with the reference region 20d when viewed from above. At this time, the positive electrode lead 20 is joined to a position on the sealing plate 24 where the protrusion 27 is not provided, as shown in Figure 2. In this embodiment, the protrusion 27 is provided on the lower surface of the sealing plate 24, as shown in Figure 2. This prevents the positive electrode lead 20 from being pulled toward the through hole 25 when air is removed from the case 15 through the through hole 25, and prevents the positive electrode lead 20 from blocking the through hole 25.

[0041] The protrusion 27 may have any of the following shapes in plan view: an arc shape, a rectangle shape, or a semicircular shape. For example, it may have a rectangular shape as shown in Figure 3. It may also have a shape that combines the above shapes, or a shape other than those described above. For example, the lower surface of the protrusion 27 may be inclined, or a groove may be formed on the lower surface. The following explanation will use the case where the protrusion 27 has a rectangular shape as an example.

[0042] As shown in FIG. 3, it is preferable that the convex portion 27 has an overlapping portion that overlaps with the positive electrode lead 20 and a non-overlapping portion that does not overlap with the positive electrode lead 20 when viewed from above. According to this, even when the positive electrode lead 20 is attracted to the through hole 25 in a displaced state, it is possible to suppress the positive electrode lead 20 from sticking to the through hole 25. The position of the convex portion 27 preferably has the same center as the through hole 25 and is closer to the outer periphery of a circle having a diameter twice that of the through hole 25. Further, when viewed from the electrode body 14 side (below), the through hole 25 is preferably between the convex portion 27 and the joint portion of the positive electrode lead 20 and the sealing plate 24. Thereby, it is more difficult for the positive electrode lead 20 to stick to the through hole 25.

[0043] The height of the convex portion 27 is preferably set based on the thickness of the positive electrode lead 20. Here, the height of the convex portion 27 means the length of the convex portion 27 along the thickness direction of the sealing plate 24. The height of the convex portion 27 is preferably 50% or more and less than 200% of the thickness of the positive electrode lead 20. According to this, since the length in the vertical direction of the convex portion 27 (the length from the lower surface of the sealing plate 24 to the lower end of the convex portion 27) is longer than the thickness of the portion where the positive electrode lead 20 is folded and overlapped (the thickness of two sheets of the positive electrode lead 20), it is possible to more effectively suppress the positive electrode lead 20 from sticking to the through hole 25.

[0044] The length in the longitudinal direction of the convex portion 27 is preferably longer than the diameter of the through hole 25. Here, the longitudinal direction of the convex portion 27 is the direction along the lower surface of the sealing plate 24. In the example shown in FIG. 3, the length in the longitudinal direction of the convex portion 27 is formed longer than the diameter of the through hole 25. By forming the length in the longitudinal direction of the convex portion 27 longer than the diameter of the through hole 25, even when the positive electrode lead 20 is displaced and attracted, it is possible to suppress the positive electrode lead 20 from sticking to the through hole 25. Also, even when the through hole 25 is small, it is easy to suppress the sticking of the wide positive electrode lead 20.

[0045] The method of forming the convex portion 27 is not particularly limited. The convex portion 27 may be formed by joining a separately created convex portion 27 to the sealing plate 24. It may also be created by press working or laser scanning. From the perspective of costs and the like, it is preferable that the convex portion 27 is formed by processing the sealing plate 24. Also, the first convex portion 28 and the second convex portion 29 described later may be formed by the same method.

[0046] The number of the convex portions 27 is not particularly limited. In the example shown in FIG. 3, there is one convex portion 27, but a plurality of them may be provided. Specifically, three or more convex portions 27 may be provided. By providing a plurality of convex portions 27, the sticking of the positive electrode lead 20 can be suppressed more effectively.

[0047] The sealing body 17 according to the second embodiment will be described using FIG. 4. The sealing body 17 according to the second embodiment is different from the sealing body 17 according to the first embodiment in that, in addition to the convex portion 27, it has a first convex portion 28 provided at a position that does not overlap with the reference region 20d.

[0048] As shown in FIG. 4, the sealing plate 24 may have a first convex portion 28 provided at a position different from the convex portion 27. The first convex portion 28 is arranged at a position that does not overlap with the positive electrode lead 20 when viewed from above. According to this, even if the positive electrode lead 20 is attracted to the through hole 25 in a displaced state, it can be suppressed from sticking to the through hole 25.

[0049] In the second embodiment, the number of the first convex portions 28 is not particularly limited. In the example shown in FIG. 4, the case where there is one first convex portion 28 is illustrated, but a plurality of first convex portions​​​​​The sealing body 17 according to the third embodiment will be described with reference to Figure 5. The sealing body 17 according to the third embodiment differs from the sealing body 17 according to the first embodiment in that it has a first protrusion 28, the overlapping and non-overlapping portions of the protrusion 27 have different heights, and the non-overlapping portions of the first protrusion 28 and protrusion 27 are located on both sides in the width direction of the positive electrode lead 20. Figure 5 is a diagram showing the sealing body 17 according to the third embodiment. Figure 5(A) is a view of the sealing plate 24 from the electrode body 14 side. Figure 5(B) is a cross-sectional view taken along line B-B of Figure 5(A). Note that in Figure 5(B), the upper insulating plate 22 is shown for illustrative purposes.

[0052] Preferably, the protrusion 27 has a non-overlapping portion 27a that does not overlap with the reference region 20d of the positive electrode lead 20 when viewed from above, and an overlapping portion 27b that overlaps with the positive electrode lead 20 when viewed from above. Here, it is preferable that the overlapping portion 27b of the protrusion 27 is lower in height than the non-overlapping portion 27a, as shown in Figure 5(B). In this case, it is preferable that the reference region 20d of the positive electrode lead 20 is positioned between the non-overlapping portion 27a and the first protrusion 28 of the protrusion 27. In detail, the non-overlapping portion 27a and the first protrusion 28 of the protrusion 27 are located on both sides in the width direction of the one-end side region 20b of the positive electrode lead 20. This makes it possible to suppress displacement of the positive electrode lead 20. It also effectively prevents the positive electrode lead 20 from sticking to the through hole 25.

[0053] In the third embodiment, the heights of the non-overlapping portion 27a and overlapping portion 27b of the protrusion 27 and the first protrusion 28 may be set based on the thickness of the positive lead 20. For example, the height of the non-overlapping portion 27a of the protrusion 27 is 150% to 200% of the thickness of the positive lead 20. The height of the overlapping portion 27b is, for example, 50% to less than 100% of the thickness of the positive lead 20. The height of the first protrusion 28 is, for example, 150% to 200% of the thickness of the positive lead 20. In this configuration, the lower surfaces of the non-overlapping portion 27a and the first protrusion 28 are located near the upper surface of the upper insulating plate 22. This configuration prevents the positive lead 20 from shifting due to the side surfaces of the non-overlapping portion 27a and the first protrusion 28. In detail, the non-overlapping portion 27a and the first protrusion 28 are arranged on both sides in the width direction of the region 20b on one end side of the positive electrode lead 20, thereby suppressing movement of the positive electrode lead 20 in the width direction. In addition, the overlapping portion 27b of the protrusion 27 prevents the positive electrode lead 20 from sticking to the through hole 25.

[0054] The sealing body 17 according to the fourth embodiment will be described in detail with reference to Figure 6. The sealing body 17 according to the fourth embodiment differs from the sealing body 17 according to the first embodiment in that it has a first protrusion 28 and a second protrusion 29. Figure 6 is a view of the sealing body 17 from above. In Figure 6, the other end region 20c is shown for explanatory purposes. Also, for clarity in the drawing, the one end region 20b is not shown.

[0055] As shown in Figure 6, the sealing plate 24 may have a second protrusion 29 provided at a different position from the protrusions 27 and the first protrusion 28. The second protrusion 29, like the first protrusion 28, is provided so as not to overlap with the positive electrode lead 20, which is a conductive member, when viewed from above. When the second protrusion 29 is provided on the sealing plate 24, as shown in Figure 6, it is preferable that the other end of the positive electrode lead 20, which is joined to the lower surface of the sealing plate 24, is joined to the sealing plate 24 between the first protrusion 28 and the second protrusion 29. That is, it is preferable that the first protrusion 28 and the second protrusion 29 are provided on both sides in the width direction of the other end that is joined to the sealing plate 24. This makes it easier to position the other end of the positive electrode lead 20.

[0056] In the fourth embodiment, the heights of the first protrusion 28 and the second protrusion 29 are not particularly limited, but may be, for example, 50% to 100% of the thickness of the positive lead 20. Also, the plan view shape of the first protrusion 28 and the second protrusion 29 is rectangular in the example shown in Figure 6, but is not limited to this. The plan view shape of the first protrusion 28 and the second protrusion 29 may be circular, rectangular, or the like.

[0057] The above embodiments can be modified as appropriate without impairing the objectives of the present invention. For example, although the above embodiments describe a case in which a protrusion 27 is provided on the sealing plate 24, if the sealing body 17 has an internal terminal plate, the protrusion 27 may be provided on the lower surface of the internal terminal plate. Also, if an internal terminal plate is provided, through holes 25 are formed in both the sealing plate 24 and the internal terminal plate.

[0058] Furthermore, although the above embodiment mainly described a protrusion 27 with a rectangular shape in plan view as an example, the plan view shape of the protrusion 27 is not limited to this. For example, the plan view shape of the protrusion 40 may have a circular arc shape in plan view, as shown in Figure 7(A). More specifically, it may have a shape in which a part of the circumference of a ring shape in plan view is missing. More specifically, it may have a C shape in plan view. Also, it is preferable that the protrusion 40 is formed around the through hole 25. Even if a part of the protrusion 40 and the positive electrode lead 20 stick together, a part of the protrusion 40 (the missing part and its vicinity) is less likely to stick to the positive electrode lead 20. This makes it possible to more effectively suppress the positive electrode lead 20 from sticking to the through hole 25. Also, as shown in Figure 7(B), the plan view shape of the protrusion 50 may be a semicircular shape. In this case, the protrusion 50 is provided so as not to overlap the through hole 25. In the example shown in Figure 7(B), about half of the central part 24a is the protrusion 50. Here, the protrusion 50 includes two non-overlapping portions that do not overlap with the positive electrode lead 20 when viewed from above, and an overlapping portion located between the two non-overlapping portions. This makes it possible to suppress the positive electrode lead 20 from sticking to the through hole 25 over a wider area. Note that the plan view shape of the protrusion of this disclosure is not limited to the shape described above. Furthermore, the plan view shape of the protrusion of this disclosure may be composed of a combination of the shapes described above.

[0059] This disclosure will be further described by the following embodiments. Configuration 1: A power storage device comprising a case having an opening, an electrode body disposed inside the case, a sealing body disposed above the electrode body and closing the opening of the case, and a conductive member electrically connecting the electrode body and the sealing body, wherein the sealing body is provided with a through hole that penetrates vertically, the through hole overlaps with the conductive member when viewed from above, and the lower surface of the sealing body is provided with a protrusion that overlaps with the conductive member when viewed from above, one end of the conductive member is connected to the electrode body and the other end is joined to the surface of the sealing body on the electrode body side where the protrusion is not provided. Configuration 2: The power storage device according to Configuration 1, wherein the through hole is provided such that the entire through hole overlaps with the conductive member when viewed from above. Configuration 3: The energy storage device according to Configuration 1 or 2, wherein the protrusion has an overlapping portion that overlaps with the conductive member when viewed from above, and a non-overlapping portion that does not overlap with the conductive member when viewed from above. Configuration 4: The energy storage device according to any one of Configurations 1 to 3, wherein the sealing body is provided at a position different from the protrusion and has a first protrusion that does not overlap with the conductive member when viewed from above. Configuration 5: The energy storage device according to Configuration 4, wherein the sealing body has a second protrusion provided at a position different from the protrusion and the first protrusion, and the other end of the conductive member is joined to the sealing body between the first protrusion and the second protrusion. Configuration 6: The energy storage device according to Configuration 4, wherein the protrusion includes a first non-overlapping portion that does not overlap with the conductive member when viewed from above, and an overlapping portion that overlaps with the conductive member when viewed from above and is lower in height than the first non-overlapping portion, and the conductive member is arranged between the non-overlapping portion and the first protrusion of the protrusion. Configuration 7: The energy storage device according to any one of Configurations 1 to 6, wherein the longitudinal length of the protrusion is longer than the diameter of the through hole. Configuration 8: The energy storage device according to claim 3, wherein the protrusion has a second non-overlapping portion that does not overlap with the conductive member when viewed from above, and the overlapping portion is located between the first non-overlapping portion and the second non-overlapping portion.

[0060] 10 Cylindrical battery 11 Positive electrode 12 Negative electrode 13 Separator 14 Electrode body 15 Case 16 Grooved section 17 Sealing section 18 Crimped section 20 Positive electrode lead 20a Folded section 20b One end side region 20c Other end side region 20d Reference region 21 Negative electrode lead 22, 23 Insulating plate 24 Sealing plate 24a Center section 24b Outer periphery section 24c Thin-walled section 24d Annular groove 24e Annular end section 25 Through hole 25a First stage 25b Second stage 26 Cover 27, 40, 50 Protrusion 27a Non-overlapping section 27b Overlapping section 28 First protrusion 29 Second protrusion 30 Gasket

Claims

1. An energy storage device comprising: a case having an opening; an electrode body disposed inside the case; a sealing body disposed above the electrode body and closing the opening of the case; and a conductive member electrically connecting the electrode body and the sealing body, wherein the sealing body has a through hole that penetrates vertically, the through hole overlaps with the conductive member when viewed from above, the lower surface of the sealing body has a protrusion that overlaps with the conductive member when viewed from above, and one end of the conductive member is connected to the electrode body and the other end is joined to the electrode body side surface of the sealing body.

2. The energy storage device according to claim 1, wherein the through hole is provided such that, when viewed from above, the entire through hole overlaps the conductive member.

3. The energy storage device according to claim 1, wherein the protrusion has, when viewed from above, an overlapping portion that overlaps with the conductive member, and a first non-overlapping portion that does not overlap with the conductive member when viewed from above.

4. The energy storage device according to claim 1, wherein the sealing body is provided at a position different from the protrusion and has a first protrusion that does not overlap with the conductive member when viewed from above.

5. The energy storage device according to claim 4, wherein the sealing body has a second protrusion provided at a position different from the protrusion and the first protrusion, and the other end of the conductive member is joined to the sealing body between the first protrusion and the second protrusion.

6. The energy storage device according to claim 4, wherein the convex portion includes a first non-overlapping portion that does not overlap with the conductive member when viewed from above, and an overlapping portion that overlaps with the conductive member when viewed from above and has a lower vertical height than the first non-overlapping portion, and the conductive member is disposed between the first non-overlapping portion and the first convex portion of the convex portion.

7. The energy storage device according to any one of claims 1 to 6, wherein the longitudinal length of the protrusion is longer than the diameter of the through hole.

8. The energy storage device according to claim 3, wherein the convex portion has a second non-overlapping portion that does not overlap with the conductive member when viewed from above, and the overlapping portion is located between the first non-overlapping portion and the second non-overlapping portion.

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