Power storage device

Abstract

This power storage device (10) comprises: a case (15) having an opening; an electrode body disposed in the case (15); a sealing body (17) disposed above the electrode body and blocking the opening of the case (15); and a conductive member (20) electrically connecting the electrode body and the sealing body (17). The sealing body (17) is provided with a through-hole (25) that passes through in the vertical direction. The sealing body (17) is provided with a groove (27), which communicates with the through-hole (25), on the surface on the electrode body side. The groove (27) has an overlapping section that overlaps the conductive member (20) when viewed from the electrode body side, and a non-overlapping section that does not overlap the conductive member (20) when viewed from the electrode body side.

Description

Electric energy storage device

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

[0002] An electric energy 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 sealing structure may be adopted to shorten the time of the electrolyte injection process. The sealing structure is formed by sealing the opening of the case with a sealing body having an electrolyte injection port, evacuating the air in the case from the electrolyte injection port, injecting an electrolyte from the electrolyte injection port, and then sealing the electrolyte injection port.

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

[0004] In an electric energy storage device having a sealing structure, when evacuating 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 electric energy storage device is reduced. Note that the electric energy storage device according to the prior document 1 cannot solve such a problem either.

[0005] The electric energy 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, and the sealing body is provided with a groove communicating with the through hole on the surface on the electrode body side. The groove has an overlapping portion that overlaps with the conductive member when viewed from the electrode body side and a non-overlapping portion that does not overlap with the conductive member when viewed from the electrode body side.

[0006] According to the electric energy storage device according to the present disclosure, it is possible to provide a more reliable electric energy storage device.

[0007] This is an axial cross-sectional view of the energy storage device according to this embodiment. This is an enlarged view of section A in Figure 1. This is a diagram showing the structure of the sealing body according to this embodiment. This is a cross-sectional view taken along line B-B in Figure 3. This is a diagram showing exhaust and injection of liquid into the case using a nozzle. This is a diagram showing a modified example of the sealing body. This is a diagram showing another example of the plan view shape of the groove.

[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 through hole 25 penetrates the case 15 in the axial direction. The plan view shape of the through hole 25 is not particularly limited. The through hole 25 is formed so as to overlap the positive electrode lead 20 when viewed from above. More specifically, the through hole 25 is formed so as to overlap the reference region 20d of the positive electrode lead 20 when viewed from above. It is also preferable that the entire through hole 25 is formed so as to overlap 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 provided 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 arrangement, as shown in Figure 5, the tip of the nozzle used for removing air from inside the case 15 and for 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 this embodiment will be described in detail with further reference to Figures 3 to 5. Figure 3 is a schematic diagram of the sealing body 17 as seen 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. Figure 4 is a cross-sectional view taken along line B-B in Figure 3. Figure 5 is a diagram showing exhaust and injection using the nozzle 28.

[0040] As shown in Figures 3 and 4, the sealing body 17 has a groove 27 on the electrode body 14 side that communicates with the through hole 25. More specifically, a groove 27 connected to the through hole 25 is provided on the lower surface of the sealing plate 24. The groove 27, when viewed from the electrode body 14 side, has a non-overlapping portion 27a that does not overlap with the conductive member, the positive electrode lead 20, and an overlapping portion 27b that overlaps with the positive electrode lead 20. As a result, even if the positive electrode lead 20 is pulled towards the through hole 25, the groove 27 allows for exhaust and injection of fluid. Consequently, manufacturing defects can be suppressed.

[0041] Figure 5 shows the state in which the reference region 20d of the positive electrode lead 20 is drawn towards the through hole 25 when air is drawn in from the nozzle 28 during exhaust. Note that the positive electrode lead 20 has moved to the lower surface of the sealing plate 24 due to the suction by the nozzle 28. As shown in Figure 5, the groove 27 allows the nozzle 28 and the internal space of the case 15 to communicate during exhaust and liquid injection by the nozzle 28. This allows exhaust to occur through the groove 27 even if the positive electrode lead 20 is drawn towards the through hole 25 during exhaust. Furthermore, although electrolyte is injected after exhaust, the exhaust device and the liquid injection device are switched at the base end (not shown) of the nozzle 28 to prevent air from entering the case 15. Therefore, the positive electrode lead 20 may be drawn towards the through hole 25 even during liquid injection after exhaust. Even in that case, it is possible to inject the electrolyte into the case 15 through the groove 27. As a result, manufacturing defects can be suppressed.

[0042] The shape of the groove 27 is not particularly limited, but as shown in Figure 3, the groove 27 may have a rectangular shape in plan view. The groove 27 may also have a circular shape or a semicircular shape in plan view. Furthermore, it may have a shape that is a combination of the above shapes, or it may have a shape other than those described above. For example, the lower surface of the groove 27 may be inclined, and the lower surface may have a corrugated groove. The following explanation will use the case where the groove 27 has a rectangular shape as an example.

[0043] The longitudinal length of the groove 27 is preferably longer than the diameter of the through hole 25. Furthermore, the sum of the diameter of the through hole 25 and the longitudinal length of the groove 27 is preferably greater than the width of the positive electrode lead 20. Here, the longitudinal direction of the groove 27 is the direction along the lower surface of the sealing plate 24. In the example shown in Figure 3, the longitudinal length of the groove 27 is formed to be longer than the diameter of the through hole 25. By forming the longitudinal length of the groove 27 to be longer than the diameter of the through hole 25, more effective exhaust and liquid injection are possible. Also, even if the through hole 25 is small, it is easier to suppress the sticking of the wide positive electrode lead 20. Note that the width of the positive electrode lead 20 refers to the short-side direction of the lead (the length in the left-right direction in Figures 3 and 4).

[0044] The depth of the groove 27 is not particularly limited, and may be set based on, for example, the thickness of the second stage 25b. For example, from the viewpoint of maintaining the strength of the sealing plate 24, the depth of the groove 27 is preferably 50% or less of the thickness of the second stage 25b. Further, the depth of the groove 27 may be set based on the thickness of the positive electrode lead 20. The depth of the groove 27 may be approximately the same as the thickness of the positive electrode lead 20. For example, the depth of the groove 27 is 70 μm or more and 150 μm or less.

[0045] The number of the grooves 27 is not particularly limited. In the example shown in FIG. 3, the number of the grooves 27 is six, but only one groove 27 may be provided. When a plurality of grooves 27 are provided, the number of passages for air or electrolyte increases during exhaust and liquid injection, so that exhaust and liquid injection can be performed more effectively.

[0046] The groove 27 includes a first groove and a second groove. When a plurality of grooves 27 are provided, it is preferable that each groove 27 is provided such that the through-hole 25 is located between the plurality of grooves 27 (for example, the first groove and the second groove). According to this, even when the positive electrode lead 20 is displaced and attracted to the through-hole 25, it is possible to prevent the positive electrode lead 20 from sticking to the entire region of the groove 27. That is, even when the positive electrode lead 20 is displaced and attracted, the non-overlapping portion 27a of the groove 27 is maintained. As a result, even when the positive electrode lead 20 is displaced and attracted to the through-hole 25, exhaust and liquid injection are possible.

[0047] As described above, the groove 27 has an overlapping portion 27b and a non-overlapping portion 27a. Specifically, as shown in FIGS. 3 and 4, the groove 27 has an overlapping portion 27b that overlaps with the reference region 20d and a non-overlapping portion 27a that does not overlap with the positive electrode lead 20 when viewed from the electrode body 14 side. In other words, the groove 27 has an overlapping portion 27b that faces the reference region 20d and a non-overlapping portion 27a that does not face the positive electrode lead 20 in the thickness direction of the sealing plate 24. Here, the area of the non-overlapping portion 27a is preferably larger than the area of the overlapping portion 27b. According to this, exhaust and liquid injection can be performed more effectively. Further, when the area of the non-overlapping portion 27a increases, the nozzle 28 can suck air over a larger area than the through-hole 25 during exhaust, so that the positive electrode lead 20 can be prevented from being attracted to the through-hole 25.

[0048] A modified example of the sealing body 17 will be explained using Figure 6. Figure 6 shows a modified example of the sealing body 17, where Figure 6(A) is a view of the sealing body 17 from the electrode body 14 side. Figure 6(B) is a cross-sectional view taken along line C-C in Figure 6(A). Figure 6(A) corresponds to Figure 3, and Figure 6(B) corresponds to Figure 4.

[0049] As described above, the sealing plate 24 has a central portion 24a with a through hole 25, an outer peripheral portion 24b that forms the outer circumference of the sealing plate 24, and a thin-walled portion 24c provided between the central portion 24a and the outer peripheral portion 24b. Here, it is preferable that the groove 27 communicates with the through hole 25 and extends to the edge of the central portion 24a, as shown in Figures 6(A) and 6(B). That is, it is preferable that the groove 27 opens to the side surface of the central portion 24a. In other words, the groove 27 is connected to a part of the inner wall of the through hole 25. This ensures more reliable communication between the through hole 25 and the internal space of the case 15. As a result, exhaust and injection can be performed more effectively. Furthermore, even if the positive electrode lead 20 shifts and sticks to the entire area of ​​the groove 27, exhaust and injection can still be performed because the groove 27 extends to the side surface of the central portion 24a.

[0050] As described above, with the energy storage device having the above configuration, exhaust and liquid injection can be performed even when the conductive member is attracted to the through hole 25 of the sealing body 17. As a result, it is possible to suppress manufacturing defects in the energy storage device and provide a highly reliable energy storage device.

[0051] 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 groove 27 is provided in the sealing plate 24, if the sealing body 17 has an internal terminal plate, the groove 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.

[0052] Furthermore, although the above embodiment mainly described a groove 27 whose plan view shape includes a rectangular shape, the plan view shape of the groove 27 is not limited to this. For example, the plan view shape of the groove 40 may be circular in plan view, as shown in Figure 7(A). This allows for exhaust and liquid injection over a wider area compared to a rectangular shape. Also, the plan view shape of the groove 50 may be semicircular, as shown in Figure 7(B). This allows for exhaust and liquid injection over a wider area. It should be noted that the plan view shape of the groove in this disclosure is not limited to the shapes described above. Moreover, the plan view shape of the groove in this disclosure may be composed of a combination of the shapes described above.

[0053] This 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 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 penetrating in the vertical direction, and the sealing body is provided with a groove on the electrode body side connected to the through hole, the groove having an overlapping portion that overlaps with the conductive member when viewed from the electrode body side, and a non-overlapping portion that does not overlap with the conductive member when viewed from the electrode body side. Configuration 2: The power storage device according to Configuration 1, wherein the through hole is provided such that, when viewed from above, the entire through hole overlaps with the conductive member. Configuration 3: The power storage device according to Configuration 1 or 2, wherein the groove includes a first groove and a second groove provided at a different position from the first groove, and the through hole is located between the first groove and the second groove. Configuration 4: The energy storage device according to any one of Configurations 1 to 3, wherein the longitudinal length of the groove is longer than the diameter of the through hole. Configuration 5: The energy storage device according to any one of Configurations 1 to 4, wherein the sum of the diameter of the through hole and the longitudinal length of the groove is greater than the width of the conductive member. Configuration 6: The energy storage device according to any one of Configurations 1 to 5, wherein the sealing body is circular when viewed from the electrode body side and has a central portion in which the through hole is provided, an outer peripheral portion that forms the outer circumference of the sealing body, and a thin-walled portion formed between the outer peripheral portion and the central portion, and the groove is provided on the electrode body side surface of the central portion and is formed to communicate from the through hole to the edge of the electrode body side surface of the central portion.

[0054] 10 Cylindrical battery 11 Positive electrode 12 Negative electrode 13 Separator 14 Electrode body 15 Case 16 Grooved section 17 Sealing body 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 Groove 27a Non-overlapping section 27b Overlapping section 28 Nozzle 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 is provided with a through hole penetrating in the vertical direction, and the sealing body is provided with a groove on the electrode body side that communicates with the through hole, and the groove has an overlapping portion that overlaps with the conductive member when viewed from the electrode body side, and a non-overlapping portion that does not overlap with the conductive member when viewed from the electrode body side.

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 groove includes a first groove and a second groove provided at a different position from the first groove, and the through hole is located between the first groove and the second groove.

4. The energy storage device according to claim 1, wherein the longitudinal length of the groove is longer than the diameter of the through hole.

5. The energy storage device according to claim 1, wherein the sum of the diameter of the through hole and the length of the groove in the longitudinal direction is greater than the width of the conductive member.

6. The energy storage device according to any one of claims 1 to 5, wherein the sealing body is circular in shape when viewed from the electrode body side, and has a central portion in which the through hole is provided, an outer peripheral portion that forms the outer circumference of the sealing body, and a thin-walled portion formed between the outer peripheral portion and the central portion, and the groove is provided on the electrode body side surface of the central portion and is formed to communicate from the through hole to the edge of the electrode body side surface of the central portion.

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