Power storage device

Abstract

This power storage device (10) comprises: a case (15) having an opening; an electrode body (14) disposed in the case (15); a sealing body (17) disposed above the electrode body (14); and a positive electrode lead (20) electrically connecting the electrode body (14) and the sealing body (17). The sealing body (17) has a sealing plate (24) provided with a through hole (25). The through hole (25) has a first portion (25P) overlapping the positive electrode lead (20) when viewed from above, and a second portion (25Q) not overlapping the positive electrode lead (20) when viewed from above.

Description

Power storage device

[0001] The present disclosure relates to a power storage device.

[0002] A power storage device includes, for example, a case having an opening, an electrode body disposed inside the case, a sealing body disposed above the electrode body, and a conductive member that electrically connects the electrode body and the sealing body (for example, Patent Document 1). Further, a manufacturing process of the power storage device includes, for example, a vacuuming step of vacuuming the inside of the case through a through hole formed in the sealing body, and a liquid injection step of injecting an electrolytic solution into the case through the through hole.

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

[0004] In the vacuuming step described above, when vacuuming the inside of the case through the through hole, the conductive member located between the sealing body and the electrode body is drawn toward the through hole, and the conductive member adheres to the electrode body-side surface (lower surface) of the sealing body, which may completely block the through hole. As a result, in the liquid injection step, the amount of the injected electrolytic solution cannot reach the specified amount, which may cause manufacturing defects. In this case, the reliability of the power storage device may be reduced.

[0005] Accordingly, an object of the present disclosure is to provide a power storage device capable of improving reliability.

[0006] The power storage device according to the present disclosure includes a case having an opening, an electrode body disposed inside the case, a sealing body disposed above the electrode body, and a conductive member that electrically connects the electrode body and the sealing body, wherein the sealing body has a sealing plate provided with a through hole, and the through hole includes a first portion overlapping the conductive member when viewed from above, and a second portion connected to the first portion and not overlapping the conductive member when viewed from above.

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

[0008] This is a plan view of the energy storage device according to this embodiment. This is a cross-sectional view of AA in Figure 1. This is a cross-sectional view of BB in Figure 1. This is a flow chart showing part of the manufacturing process of the energy storage device. This is a cross-sectional view showing the vacuuming process of the energy storage device. This is a plan view showing a through hole according to another example of the embodiment. This is a plan view showing a through hole according to another example of the embodiment. This is a plan view showing a through hole according to another example of the embodiment. This is a plan view showing a through hole according to another example of the embodiment.

[0009] An example of an embodiment of this disclosure is described in detail below. In the following description, specific shapes, materials, directions, numerical values, etc., are examples provided to facilitate understanding of this disclosure and can be modified as appropriate to suit the application, purpose, specifications, etc.

[0010] [Energy Storage Device] An example of an embodiment, an energy storage device 10, will be described using Figures 1 to 3.

[0011] 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.

[0012] The energy storage device 10 comprises a wound electrode body 14, a bottomed cylindrical case 15 that houses the electrode body 14, and a sealing body 17 positioned above the electrode body 14 and closing the opening of the case 15. The energy storage device 10 includes an electrolyte, which is housed in the case 15 together with the electrode body 14. As will be described in detail later, the sealing body 17 has a through hole 25 that penetrates vertically and connects the internal space and external space of the case 15.

[0013] 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, with the direction from the electrode body 14 toward the seal body 17 being considered "up".

[0014] The electrode body 14 has a positive electrode, a negative electrode, and a separator, and has a wound structure in which the positive electrode and negative electrode are wound in a spiral shape with the separator in between. The positive electrode, negative electrode, and separator 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 is formed to be slightly larger in dimensions than the positive electrode in order to prevent lithium deposition. That is, the negative electrode is formed to be longer in the longitudinal direction and the width direction (short direction) than the positive electrode. The separator is formed to be at least slightly larger in dimensions than the positive electrode, and two separators are arranged so as to sandwich the positive electrode.

[0015] 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 case 15, extending circumferentially and projecting radially inward. The radial length of the groove 16 on 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 sealing body 17 side of the energy storage device 10 will be considered the top, and the bottom side of case 15 will be considered the bottom. The groove 16 is preferably formed in an annular shape along the circumferential direction of case 15, and its upper surface supports the sealing body 17. The sealing body 17 and gasket 30 are fixed to the upper part of case 15 by the groove 16 and the open end of case 15 that is crimped to the sealing body 17 and gasket 30. The opening of case 15 is circular in plan view, and the sealing body 17 is similarly circular in plan view.

[0016] 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) or a solid electrolyte. The energy storage device 10 is a non-aqueous electrolyte secondary battery, and among these, a lithium-ion battery is preferred.

[0017] 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.

[0018] 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.

[0019] The positive electrode comprises 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 positive electrode potential range, 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, a binder, etc. The positive electrode can be manufactured, 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, drying the coating, and then compressing it to form positive electrode mixture layers on both sides of the positive electrode core.

[0020] 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.

[0021] 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.

[0022] The negative electrode comprises a negative electrode core and negative electrode mixture layers 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 in the negative electrode potential range, 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 layers contain a negative electrode active material, a binder, etc. The negative electrode can be manufactured, for example, by applying a negative electrode mixture slurry containing a negative electrode active material, a binder, etc., onto the negative electrode core, drying the coating, and then compressing it to form negative electrode mixture layers on both sides of the negative electrode core.

[0023] 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.

[0024] The binder included in the negative electrode mixture layer may be fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, etc., as in the positive electrode, 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.

[0025] A porous sheet with ion permeability and insulating properties is used as the separator. Specific examples of porous sheets include microporous thin films, woven fabrics, and nonwoven fabrics. Suitable materials for the separator (porous sheet) include polyethylene, polyolefins such as polypropylene, and cellulose. The separator may have a single-layer structure or a multi-layer structure. Furthermore, a heat-resistant resin layer, such as aramid resin, may be formed on the surface of the separator.

[0026] The electrode body 14 further includes a positive electrode lead 20 that functions as a conductive member to electrically connect the positive electrode of the electrode body 14 to the sealing body 17, and a negative electrode lead that electrically connects the negative electrode to the case 15. One end of the positive electrode lead 20 is connected to the core of the positive electrode 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. The positive electrode lead 20 is positioned so as to coincide with the radial center of the sealing body 17 when viewed from above, and is bent and welded to the lower surface of the central part 24A of the sealing plate 24 of the sealing body 17. One end of the negative electrode lead is connected to the core of the negative electrode, and the other end is connected to the bottom inner surface of the case 15 by welding or the like, so that the case 15 becomes the negative electrode external terminal.

[0027] An upper insulating plate 22 and a lower insulating plate are positioned 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 is provided between the electrode body 14 and the bottom of the case 15. In the example shown in Figures 2 and 3, the positive electrode lead 20 extends towards the sealing body 17 through a through hole in the upper insulating plate 22, and the negative electrode lead extends towards the bottom of the case 15 through the outside of the lower insulating plate.

[0028] [Sealing body] The sealing body 17 is a member that closes the opening of the case 15 via the gasket 30. 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 provided with the through hole 25 and a lid member 26 provided in the sealing plate 24 for closing the through hole 25.

[0029] [Sealing Plate] The sealing plate 24 has a circular shape in plan view. The sealing plate 24 can be made, for example, by press-forming a sheet of aluminum or an aluminum alloy. Aluminum and aluminum alloys are preferred as materials for the sealing plate 24 that functions as an explosion-proof valve because they have excellent flexibility. The sealing plate 24 has a central portion 24A in which a through hole 25 is provided, an outer peripheral portion 24B that extends radially outward from the central portion 24A to the case 15, and a thin-walled portion 24C that connects the central portion 24A and the outer peripheral portion 24B.

[0030] With the sealing plate 24 described above, when the internal pressure of the energy storage device 10 reaches a predetermined value, gas can be released. Specifically, when the internal pressure of the energy storage device 10 reaches a predetermined value, the central part 24A and the thin part 24C of the sealing plate 24 invert upward in the height direction, using the radially outward annular end, which has lower rigidity in the thin part 24C, as a fulcrum. Furthermore, as the internal pressure rises, the annular end of the thin part 24C ruptures, and the gas inside the energy storage device 10 is discharged to the outside from the rupture in the sealing plate 24. This prevents the energy storage device 10 from rupturing even when the internal pressure of the energy storage device 10 rises.

[0031] The sealing body 17 may 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.

[0032] [Through Hole] As described above, the through hole 25 is provided in the central part 24A of the sealing plate 24. As will be described in detail later, in the manufacturing process of the energy storage device 10, the inside of the case 15 is vacuumed from the through hole 25, electrolyte is injected into the inside of the case 15 from the through hole 25, and the through hole 25 is sealed by the lid member 26. The through hole 25 has a circular part 25A formed approximately in the center of the central part 24A of the sealing plate 24. It also has a protruding part 25B that protrudes radially outward from the circular part 25A of the case 15.

[0033] The diameter of the circular portion 25A is smaller than, for example, the width of the positive electrode lead 20. Also, as described above, the positive electrode lead 20 is positioned so as to coincide with the radial center of the sealing body 17 when viewed from above. Therefore, the circular portion 25A overlaps with the positive electrode lead 20 when viewed from above. The protruding portion 25B extends to a portion that does not overlap with the positive electrode lead 20 when viewed from above. Therefore, the protruding portion 25B includes a portion that overlaps with the positive electrode lead 20 and a portion that does not overlap with the positive electrode lead 20.

[0034] Here, in the through hole 25, the portion that overlaps with the positive lead 20 when viewed from above is defined as the first portion 25P, and the portion that does not overlap with the positive lead 20 when viewed from above is defined as the second portion 25Q. In other words, both the first portion 25P and the second portion 25Q are parts of a single through hole 25, and the first portion 25P and the second portion 25Q are connected. In the through hole 25 of this embodiment, the circular portion 25A corresponds to the first portion 25P, and the protruding portion 25B includes the first portion 25P and the second portion 25Q. In other words, the through hole 25 has a second portion 25Q that does not overlap with the positive lead 20 when viewed from above, by providing the protruding portion 25B.

[0035] Conventionally, when vacuuming from the through-hole 25, the positive electrode lead 20, located between the sealing body 17 and the electrode body 14, was sometimes pulled towards the through-hole 25, causing the positive electrode lead 20 to stick to the lower surface of the sealing plate 24 and completely block the through-hole 25. As a result, the vacuuming inside the case 15 was not sufficiently performed, resulting in an incomplete vacuum state. In this case, the amount of electrolyte injected did not reach the specified amount, which could lead to a manufacturing defect. This could reduce the reliability of the energy storage device 10.

[0036] The through-hole 25 of this embodiment has a second portion 25Q that does not overlap with the positive electrode lead 20 when viewed from above. As a result, when vacuuming is performed from the through-hole 25, the through-hole 25 will not be completely blocked if the positive electrode lead 20 sticks to the lower surface of the sealing body 17. In other words, even if the positive electrode lead 20 sticks to the lower surface of the sealing body 17, vacuuming is possible from the second portion 25Q. As a result, the reliability of the energy storage device 10 can be improved.

[0037] The second portion 25Q is larger than the first portion 25P. More specifically, when viewed from above, the area of ​​the second portion 25Q is larger than the area of ​​the first portion 25P. This prevents the through-hole 25 from being formed to be unnecessarily large, and ensures that the strength of the sealing plate 24 does not fall below a predetermined strength. Furthermore, the function of the sealing plate 24 as an explosion-proof valve is not impaired.

[0038] In this embodiment, the second portion 25Q is formed only at one location on the tip of the protruding portion 25B, but the present invention is not limited thereto. The second portion 25Q may be formed at multiple locations. This allows for vacuuming from multiple locations when the positive electrode lead 20 is stuck to the lower surface of the sealing body 17 during vacuuming from the through hole 25. Since the through hole 25 only needs to include the first portion 25P and the second portion 25Q, vacuuming from the second portion 25Q is possible even if the position of the positive electrode lead 20 is shifted and the following relationship occurs, or even if the positive electrode lead 20 is stuck to the lower surface of the sealing body 17. For example, the circular portion 25A may include the first portion 25P and the second portion 25Q, and the protruding portion 25B may correspond to the second portion 25Q. Furthermore, the circular portion 25A may include the first portion 25P and the second portion 25Q, and the protruding portion 25B may include the first portion 25P and the second portion 25Q.

[0039] [Cover Member] The cover member 26 is a member that seals the through hole 25. The cover member 26 prevents electrolyte from leaking from the through hole 25. The material of the cover member 26 is not particularly limited, but it may be made of the same material as the sealing plate 24. The cover member 26 has a covering portion 26A that covers the entire through hole 25 and the upper surface of the central portion 24A, and an insertion portion 26B that protrudes downward from the covering portion 26A and is inserted into the through hole 25.

[0040] The covering portion 26A is formed in a disc shape, provided on the upper surface of the central portion 24A, and is the part that closes the through hole 25. In other words, the covering portion 26A covers the entire through hole 25 and a part of the upper surface of the central portion 24A. The periphery of the covering portion 26A is welded to the central portion 24A of the sealing plate 24. The covering portion 26A can seal the through hole 25.

[0041] The insertion portion 26B is a portion formed in a columnar shape, an elliptical columnar shape or the like protruding downward from the covering portion 26A, and inserted into a part of the through hole 25. The insertion portion 26B of the present embodiment is, for example, formed in a columnar shape having a diameter slightly smaller than that of the circular portion 25A of the through hole 25, and is inserted into the circular portion 25A. Here, it is preferable that the insertion portion 26B of the lid member 26 has a shape close to that of the circular portion 25A of the through hole 25. According to the insertion portion 26B, the position of the lid member 26 relative to the sealing plate 24 can be easily determined. Note that the through hole 25 may be provided on the bottom surface of a recess provided in the central portion 24A. Since the covering portion 26A of the lid member 26 can be arranged in the recess by means of the insertion portion 26B, positional displacement of the lid member 26 is less likely to occur.

[0042] [Gasket] The gasket 30 is a sealing member disposed on the opening side of the case 15 and between the sealing body 17 and the case 15. By sealing the space between the case 15 and the sealing body 17 with the annular gasket 30, the internal space of the case 15 is hermetically sealed. Further, the gasket 30 insulates the sealing body 17 from the case 15. That is, the gasket 30 functions as a sealing material for maintaining airtightness inside the power storage device 10 and as an insulating material for preventing a short circuit between the case 15 and the sealing body 17.

[0043] The gasket 30 is fixed to the upper end of the case 15 by the grooved portion 16 of the case 15 and the caulked portion 18 which is the opening edge of the case 15 caulked against the sealing body 17 and the gasket 30. Further, after caulking and fixing, the gasket 30 is arranged so as to be positioned between the sealing body 17 and the caulked portion 18, and between the sealing body 17 and the grooved portion 16.

[0044] [Manufacturing Process of Power Storage Device] A manufacturing process of the power storage device 10 will be described with reference to FIGS. 4 and 5.

[0045] As illustrated in FIG. 4, the manufacturing process of the power storage device 10 includes, for example, an electrode body inserting step S11, a case grooving step S12, a sealing step S13, a vacuum evacuating step S14, an electrolyte injecting step S15, a plugging step S16, and a plugging welding step S17.

[0046] In the electrode body inserting step S11, an electrode body 14 is inserted into a bottomed cylindrical case 15. In the case grooving step S12, a grooved portion 16 projecting radially inward by spinning processing from the outside is formed in the vicinity of the upper end opening of the case 15 into which the electrode body 14 has been inserted. In the sealing step S13, a gasket 30 and a sealing body 17 are arranged on the grooved portion 16, and the gasket 30 and the sealing body 17 are caulked and fixed by the upper end portion of the case 15.

[0047] As illustrated in FIG. 5, in the evacuation step S14, a nozzle N is inserted into the through hole 25 of the sealing plate 24, and the inside of the case 15 is evacuated. In the electrolyte injecting step S15, an electrolyte is injected from the nozzle N that is also inserted into the through hole 25. In the plugging step S16, a lid member 26 is inserted into the through hole 25. In the plug welding step S17, the periphery of the covering portion 26A of the lid member 26 is joined to the sealing plate 24 by welding.

[0048] Conventionally, in the evacuation step S14, when evacuation is performed through the through hole 25, the positive electrode lead positioned between the sealing body 17 and the electrode body 14 is drawn toward the through hole 25, and the positive electrode lead adheres to the lower surface of the sealing plate 24, which may completely block the through hole 25. As a result, in the evacuation step S14, evacuation is not sufficiently performed, and the inside of the case 15 becomes an incomplete vacuum state. In this case, in the electrolyte injecting step S15, the amount of the injected electrolyte cannot reach the specified amount, which may cause manufacturing defects. This may lead to a decrease in the reliability of the power storage device 10.

[0049] According to the power storage device 10 of the present embodiment, as described above, the through hole 25 has the second portion 25Q that does not overlap with the positive electrode lead 20 when viewed from above. This prevents the through hole 25 from being completely blocked when the positive electrode lead adheres to the lower surface of the sealing body 17 during evacuation through the through hole 25. In other words, even when the positive electrode lead adheres to the lower surface of the sealing body 17, evacuation can be performed through the second portion 25Q. As a result, the reliability of the power storage device 10 can be improved.

[0050] [Through Hole (Other Embodiments)] A through hole 25, which is another example of the embodiment, will be described using Figures 6 to 10.

[0051] The through-hole 25 will be described below, but the other components are the same as those of the energy storage device 10 described above and will not be explained. In addition, the positive electrode lead 20 is positioned so as to coincide with the radial center of the sealing body 17 when viewed from above.

[0052] As illustrated in Figure 6, the through-hole 25 has a circular portion 25A formed approximately in the center of the central portion 24A of the sealing plate 24, and two protruding portions 25B that project radially outward from the circular portion 25A of the case 15 (away from the central axis of the case 15). The diameter of the circular portion 25A is, for example, smaller than the width of the positive electrode lead 20. Therefore, the circular portion 25A overlaps with the positive electrode lead 20 when viewed from above. The protruding portions 25B extend to a portion that does not overlap with the positive electrode lead 20 when viewed from above. Therefore, the protruding portions 25B include a portion that overlaps with the positive electrode lead 20 and a portion that does not overlap with the positive electrode lead 20. The two protruding portions 25B may, for example, be formed in the same straight line. In the through-hole 25 of this embodiment, the circular portion 25A corresponds to the first portion 25P, and the protruding portions 25B include the first portion 25P and the second portion 25Q. More specifically, the first part 25P and the second part 25Q are connected. In this case, even if the positive lead 20 is positioned offset in either direction along the longitudinal direction of the through hole 25, the positive lead 20 is less likely to block the through hole 25.

[0053] As illustrated in Figure 7, the through-hole 25 is formed as a square with rounded corners in the central part 24A of the sealing plate 24. The length of one side of the square forming the through-hole 25 is greater than the width of the positive lead 20. Therefore, the circular part 25A includes a part that overlaps with the positive lead 20 when viewed from above, and a part that does not overlap with the positive lead 20. In other words, the through-hole 25 includes a first part 25P and a second part 25Q. In this case, even if the arrangement angle of the positive lead 20 is shifted, the positive lead 20 is less likely to block the through-hole 25.

[0054] As illustrated in Figure 8, the through-hole 25 is formed by combining multiple elongated hole shapes. The longitudinal length of each elongated hole shape is greater than the width of the positive electrode lead 20. Each elongated hole shape is combined such that its center is located at the center of the sealing plate 24. Therefore, the circular portion 25A includes a portion that overlaps with the positive electrode lead 20 when viewed from above, and a portion that does not overlap with the positive electrode lead 20. In other words, the through-hole 25 includes a first portion 25P and a second portion 25Q. In this case, even if the arrangement angle of the positive electrode lead 20 is shifted, the positive electrode lead 20 is less likely to block the through-hole 25.

[0055] As illustrated in Figure 9, the through-hole 25 is formed in a regular hexagonal shape in the central part 24A of the sealing plate 24. The distance between opposing corners of the regular hexagon is greater than the width of the positive electrode lead 20. Therefore, the circular part 25A includes a portion that overlaps with the positive electrode lead 20 when viewed from above, and a portion that does not overlap with the positive electrode lead 20. In other words, the through-hole 25 includes a first portion 25P and a second portion 25Q. In this case, even if the arrangement angle of the positive electrode lead 20 is shifted, the positive electrode lead 20 is less likely to block the through-hole 25.

[0056] As illustrated in Figure 10, the through-hole 25 has a circular portion 25A formed at a position offset radially to one side from approximately the center of the central portion 24A of the sealing plate 24. It also has a protruding portion 25B that projects radially to the other side of the case 15 (towards the central axis of the case 15). Furthermore, the protruding portion 25B is located in a position that coincides with the central axis of the case 15. The circular portion 25A includes a portion that overlaps with the positive electrode lead 20 when viewed from above, and a portion that does not overlap with the positive electrode lead 20. The protruding portion 25B overlaps with the positive electrode lead 20 when viewed from above. In other words, in the through-hole 25, the circular portion 25A includes a first portion 25P and a second portion 25Q, and the protruding portion 25B corresponds to the first portion 25P. Furthermore, the through-hole 25 may consist only of a circular portion 25A formed at a position offset radially to one side from approximately the center of the central portion 24A of the sealing plate 24. The presence of a protruding portion 25B in addition to the circular portion 25A increases the combined length of the circular portion 25A and the protruding portion 25B (the width of the through-hole). Therefore, even if the diameter of the circular portion 25A is smaller than the width of the positive electrode lead 20, it is easier to absorb any misalignment of the positive electrode lead 20 (making it less likely for the positive electrode lead 20 to block the through-hole 25).

[0057] [Summary] The present disclosure is further illustrated by the following embodiments. Configuration 1: A power storage device comprising: a case having an opening; an electrode body disposed within the case; a sealing body disposed above the electrode body; and a conductive member electrically connecting the electrode body and the sealing body, wherein the sealing body has a sealing plate with a through hole, and the through hole has a first portion that overlaps with the conductive member when viewed from above, and a second portion that is connected to the first portion and does not overlap with the conductive member when viewed from above. Configuration 2: The power storage device according to Configuration 1, wherein the size of the first portion of the through hole is larger than the size of the second portion of the through hole. Configuration 3: The power storage device according to Configuration 1, wherein the through hole has a plurality of second portions. Configuration 4: The power storage device according to Configuration 1, wherein the through hole has a circular portion and a projection that protrudes radially outward from the circular portion of the case. Configuration 5: The energy storage device according to Configuration 4, wherein the circular portion is the first portion of the through hole, and the protruding portion includes the first and second portions of the through hole. Configuration 6: The energy storage device according to Configuration 1, wherein the through hole has a circular portion and a protruding portion that protrudes radially inward from the circular portion of the case. Configuration 7: The energy storage device according to any one of Configurations 1 to 5, further comprising a lid member inserted into the through hole, wherein the sealing plate has a central portion in which the through hole is provided, an outer peripheral portion extending radially outward from the central portion of the case, and a thin-walled portion connecting the central portion and the outer peripheral portion, and the lid member has a covering portion that covers the entire through hole and the upper surface of the central portion, and an insertion portion that protrudes downward from the covering portion and is inserted into the through hole.

[0058] It should be noted that this disclosure is not limited to the embodiments and their modifications described above, and various changes and improvements are possible within the scope of the claims of this application.

[0059] 10 Energy storage device, 14 Electrode body, 15 Case, 16 Grooved section, 17 Sealing body, 18 Crimping section, 20 Positive electrode lead (conductive member), 22 Upper insulating plate, 24 Sealing plate, 24A Central section, 24B Outer periphery section, 24C Thin-walled section, 25 Through hole, 25A Circular section, 25B Protruding section, 26 Cover member, 26A Covering section, 26B Insertion section, 30 Gasket, N Nozzle

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 a conductive member electrically connecting the electrode body and the sealing body, wherein the sealing body has a sealing plate with a through hole, and the through hole has a first portion that overlaps with the conductive member when viewed from above, and a second portion that does not overlap with the conductive member when viewed from above.

2. The energy storage device according to claim 1, wherein the size of the first portion of the through hole is larger than the size of the second portion of the through hole.

3. The energy storage device according to claim 1, wherein the through hole has a plurality of the second portion.

4. The energy storage device according to claim 1, wherein the through hole has a circular portion and a protruding portion that protrudes radially outward from the circular portion of the case.

5. The energy storage device according to claim 4, wherein the circular portion is the first portion of the through hole, and the protruding portion includes the first portion and the second portion of the through hole.

6. The energy storage device according to claim 1, wherein the through hole has a circular portion and a protruding portion that protrudes radially inward from the circular portion of the case.

7. The energy storage device according to any one of claims 1 to 5, further comprising a lid member inserted into the through hole, wherein the sealing plate has a central portion in which the through hole is provided, an outer peripheral portion extending radially outward from the central portion of the case, and a thin-walled portion connecting the central portion and the outer peripheral portion, and the lid member has a covering portion that covers the entire through hole and the upper surface of the central portion, and an insertion portion that protrudes downward from the covering portion and is inserted into the through hole.

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