Power storage device

Abstract

The present invention comprises an electrode body (14) that includes a positive electrode (11) and a negative electrode (12), a case (20) that accommodates the electrode body (14), and a sealing body (30) that closes the opening of the case (20). The sealing body (30) includes a sealing plate (31) that is electrically connected to the positive electrode (11), and a positive electrode terminal (32) that is disposed on the sealing plate (31) and is electrically connected to the sealing plate (31). The sealing plate (31) has a first surface facing toward the electrode body (14), and a second surface positioned on the axially opposite side from the first surface. The positive electrode terminal (21) is disposed on the second surface. The sealing plate (31) deforms in a direction away from the electrode body (14) in the axial direction P when the pressure within the case (20) increases. A holding part that covers the outer peripheral surface of the positive electrode terminal (32) and holds the positive electrode terminal (32) is formed on the second surface of the sealing plate (31).

Description

Power storage device

[0001] The present disclosure relates to an electricity storage device.

[0002] The power storage device includes an electrode assembly in which a positive electrode, a negative electrode, and a separator are wound together, a case that contains the electrode assembly and an electrolyte, and a sealing body that closes the opening of the case. The sealing body may include a sealing plate that is electrically connected to the positive electrode and a terminal that is fixed to the upper surface of the sealing plate (for example, Patent Document 1).

[0003] International Publication No. 2021 / 200737

[0004] According to the energy storage device disclosed in Patent Document 1, by disposing a terminal member on a portion of the sealing plate, it is possible to prevent the sealing plate from becoming thicker than in a configuration in which the entire sealing plate has a multi-layer structure, and it is possible to increase the energy density without increasing the height of the shoulder portion (crimped portion) of the case. However, in this energy storage device, it is necessary to further improve reliability while increasing the energy density.

[0005] Therefore, an object of the present disclosure is to provide a power storage device that can improve reliability.

[0006] The energy storage device according to the present disclosure comprises an electrode body including a first electrode and a second electrode, a case that houses the electrode body, and a sealing body that closes an opening of the case, the sealing body including a sealing plate that is electrically connected to the first electrode, and a terminal that is disposed on the sealing plate and electrically connected to the sealing plate, the sealing plate having a first surface facing the electrode body and a second surface that is located opposite the first surface in the axial direction, the terminal being disposed on the second surface, the sealing plate deforming in the axial direction away from the electrode body when pressure inside the case increases, and a holding portion that covers the outer peripheral surface of the terminal and holds the terminal formed on the second surface of the sealing plate.

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

[0008] FIG. 1 is a schematic cross-sectional view showing an energy storage device according to an embodiment; FIG. 2 is a cross-sectional view perpendicular to the circumferential direction showing a part of a sealing plate according to an embodiment; FIG. 3 is a schematic view showing a state in which the sealing plate is inverted due to an increase in internal pressure; FIG. 4 is a cross-sectional view perpendicular to the circumferential direction showing a part of a sealing body according to another embodiment; FIG. 5 is a schematic cross-sectional view showing an energy storage device according to another embodiment; FIG. 6 is a perspective view showing a sealing plate according to another embodiment; FIG. 7 is a schematic cross-sectional view showing an energy storage module according to an embodiment;

[0009] An example of an embodiment of the present disclosure will be described in detail below. In the following description, specific shapes, materials, directions, numerical values, etc. are examples for facilitating understanding of the present disclosure, and can be appropriately changed according to the application, purpose, specifications, etc.

[0010] [Power Storage Device] A power storage device 10 according to an example embodiment will be described with reference to FIG.

[0011] The energy storage device 10 includes an electrode assembly 14 in which a positive electrode 11 as a first electrode and a negative electrode 12 as a second electrode are wound with a separator 13 interposed therebetween, a case 20 that houses the electrode assembly 14, and a sealing body 30 that closes the opening of the case 20. The case 20 houses an electrolyte together with the electrode assembly 14. The electrolyte in this embodiment is a non-aqueous electrolyte, but may be an aqueous electrolyte. The energy storage device 10 may be a capacitor. The sealing body 30 is provided with a sealing plate 31 that is electrically connected to the positive electrode 11, and a positive electrode terminal 32 that serves as a terminal fixed to the upper surface of the sealing plate 31 with its upper side open.

[0012] In this embodiment, as will be described in detail later, the positive electrode 11 and the sealing plate 31 are electrically connected, and the terminal functions as a positive electrode terminal 32, and the negative electrode 12 and the case 20 are electrically connected, and the case 20 functions as a negative electrode terminal. However, in the energy storage device disclosed herein, the sealing plate and the negative electrode may be electrically connected, and the terminal may function as a negative electrode terminal, and the positive electrode and the case may be electrically connected, and the case may function as a positive electrode terminal. In other words, the first electrode may be the negative electrode, and the second electrode may be the positive electrode.

[0013] In the following, each member may be described using the axial direction P, the circumferential direction R, and the radial direction D. For ease of explanation, the side in the axial direction P where the sealing plate 31 is provided may be described as the upper side, and the side where the bottom 20B of the case 20 is formed may be described as the lower side. Furthermore, the radial direction D may be described as the inside or outside. For ease of explanation, the term radial direction D is used, but the case of the power storage device of the present disclosure does not have to be cylindrical. It may be a square tube.

[0014] According to the energy storage device 10, as will be described in detail later, if an abnormality occurs in the energy storage device 10 and the internal pressure rises, causing the sealing plate 31 to invert (deform), the positive electrode terminal 32 can be detached from the sealing plate 31, and the electrical connection between the sealing plate 31 and the positive electrode terminal 32 can be cut off. This can improve the reliability of the energy storage device 10.

[0015] The positive electrode 11 includes, for example, a strip-shaped positive electrode core material and a positive electrode mixture layer formed on at least one surface of the positive electrode core material. A positive electrode core material exposed portion where the positive electrode core material is not provided with a positive electrode mixture layer is provided midway along the length of the positive electrode 11. One end of the positive electrode tab 15 is joined to this positive electrode core material exposed portion. The positive electrode core material may be a foil of a metal, such as aluminum or an aluminum alloy, that is stable within the potential range of the positive electrode 11, or a film with such a metal disposed on its surface. In the positive electrode of the present disclosure, a positive electrode core material exposed portion may be formed at one end of the width direction of the positive electrode core material, and the end surface of the electrode body formed from this exposed positive electrode core material may be joined to a current collector plate, electrically connecting the current collector plate and the sealing plate.

[0016] The positive electrode mixture layer includes a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride, and is formed on both sides of the positive electrode core material, for example. The positive electrode active material may be, for example, a lithium transition metal composite oxide.

[0017] The negative electrode 12 has a negative electrode core material and a negative electrode mixture layer formed on at least one surface of the negative electrode core material. The negative electrode core material can be, for example, a foil of a metal stable within the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with such a metal disposed on the surface. The negative electrode mixture layer preferably contains, for example, a negative electrode active material and a binder such as styrene-butadiene rubber (SBR), and is formed on both sides of the negative electrode core material. Examples of the negative electrode active material include graphite and silicon-containing compounds. A negative electrode core material exposed portion is formed midway along the length of the negative electrode 12, where the negative electrode mixture layer is not applied to the negative electrode core material. One end of a negative electrode tab is joined to this negative electrode core material exposed portion. In the negative electrode disclosed herein, a positive electrode core material exposed portion may be formed at one widthwise end of the negative electrode core material, and the end face of the electrode body composed of this exposed positive electrode core material may be joined to a current collector plate, electrically connecting the current collector plate and the case.

[0018] The electrolyte is a non-aqueous electrolyte and includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous solvent include esters, ethers, nitriles, amides, and mixed solvents of two or more of these. The non-aqueous solvent may contain a halogen-substituted compound in which at least a portion of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine. Examples of the non-aqueous solvent include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and mixed solvents thereof. The electrolyte salt includes, for example, LiPF ６ Lithium salts such as

[0019] The electrode assembly 14 is formed into a cylindrical shape by winding a positive electrode 11 and a negative electrode 12 around a winding core (not shown) with a separator 13 interposed therebetween, with the positive electrode core exposed portion and the negative electrode core exposed portion being offset so as to protrude to opposite sides in the axial direction P. Note that the electrode assembly of the present disclosure may be formed by zigzag folding rather than winding the positive electrode, negative electrode, and separator. Furthermore, the electrode assembly of the present disclosure may be a laminate in which multiple positive electrodes, negative electrodes, and separators are alternately stacked. In the case of a laminate, multiple positive electrode tabs joined to each positive electrode plate may be provided.

[0020] Provided above the electrode body 14 are a positive electrode tab 15 that extends from the upper end of the electrode body 14 and connects the positive electrode 11 constituting the electrode body 14 to a sealing plate 31, and an upper insulating plate 16 that is disposed between the electrode body 14 and the sealing plate 31. The positive electrode tab 15 electrically connects the positive electrode 11 to the sealing plate 31. This electrically connects a positive electrode terminal 32, which will be described later, to the positive electrode 11. The upper insulating plate 16 prevents the positive electrode 11 and the positive electrode tab 15 from contacting the case 20, and also prevents the positive electrode tab 15 from contacting the negative electrode 12 of the electrode body 14.

[0021] Below the electrode body 14, there are provided a negative electrode tab (not shown) that extends from the lower end of the electrode body 14 and connects the negative electrode 12 constituting the electrode body 14 to the inner bottom surface of the case 20, and a lower insulating plate (not shown) that is disposed between the electrode body 14 and the inner surface of the bottom 20B of the case 20. The negative electrode tab electrically connects the negative electrode 12 to the inner surface of the bottom 20B of the case 20. This allows the case 20 to function as a negative electrode terminal. The lower insulating plate prevents the negative electrode 12 and the negative electrode tab from contacting the case 20, and also prevents the negative electrode tab from contacting the positive electrode 11 of the electrode body 14.

[0022] The case 20 is, for example, a cylindrical metal container with a bottom and an open top. The case 20 is generally made of a metal primarily composed of iron, but may be made of a metal primarily composed of aluminum or the like when the positive electrode 11 is connected. The case 20 has a cylindrical tubular portion 20A, a bottom portion 20B that is circular in bottom view, a shoulder portion 20C that extends inward from the open end of the tubular portion 20A and is formed in an annular shape, and a groove portion 20D that is formed along the circumferential direction R of the tubular portion 20A. The case 20 may also be a rectangular tubular portion.

[0023] Groove 20D is formed near the opening of case 20 at a position a predetermined distance away from shoulder 20C. Groove 20D is a portion of tubular portion 20A that protrudes inward of case 20, and is formed, for example, by spinning tubular portion 20A from the outside. Note that at the position where groove 20D is formed, the diameter of case 20 is reduced, and a thin groove is formed on the outer circumferential surface of tubular portion 20A. Groove 20D preferably has a substantially U-shaped cross section and is formed in an annular shape over the entire length of tubular portion 20A in the circumferential direction R.

[0024] [Sealing Body] The sealing body 30 will be described with reference to FIGS. 1 to 4. FIG.

[0025] As shown in Fig. 1 , the sealing body 30 is configured, for example, in a disk shape overall. If the case 20 is in a rectangular cylindrical shape, the sealing body 30 may be in a polygonal plate shape. The sealing body 30 is placed on the groove 20D of the case 20 and fixed to the upper end of the case 20. More specifically, the shoulder 20C of the case 20 is bent inward and crimped against the sealing body 30, and the sealing body 30 is fixed to the upper end of the case 20 by the shoulder 20C and groove 20D of the case 20, so that the sealing body 30 closes the opening of the case 20.

[0026] The sealing body 30 includes a sealing plate 31, a positive electrode terminal 32 fixed to the upper surface of the sealing plate 31, a gasket 33 provided on the outer periphery 31A of the sealing plate 31, and an insulating member 34 provided below the sealing body 30, each of which will be described in detail below.

[0027] The sealing plate 31 is formed, for example, in a disk shape and is made of a conductive material, such as aluminum or an aluminum alloy. The sealing plate 31 has a first surface facing the electrode assembly 14 in the axial direction P and a second surface opposite the first surface. The sealing plate 31 has an outer peripheral portion 31A that is crimped to the opening of the case 20, a central portion 31B formed inside the outer peripheral portion 31A, an annular wall portion 31C that protrudes upward from the second surface of the central portion 31B as a retaining portion, a protrusion 31D that protrudes downward from the first surface of the central portion 31B and to which the positive electrode tab 15 is joined, and a thin-walled portion 31E interposed between the outer peripheral portion 31A and the central portion 31B. Note that the retaining portion of the sealing plate 31 need only be located near the portion that is farthest from the electrode assembly 14 (displaced most in the axial direction P) when pressure inside the case 20 increases; it does not necessarily have to be located at the central portion 31B of the sealing plate 31. If a position other than the center of the sealing plate 31 is farthest from the electrode body 14, the holding portion is disposed at that off-center position.

[0028] The positive electrode terminal 32 is a positive electrode welding terminal for connecting the energy storage devices 10 in series or parallel, for example, when configuring the energy storage devices 10 as an energy storage module. The positive electrode terminal 32 is formed in a substantially disk shape and is made of, for example, iron, nickel, stainless steel, copper, or the like. The positive electrode terminal 32 may also be made of the same material as the sealing plate 31, for example, aluminum or an aluminum alloy. The positive electrode terminal 32 has a protrusion 32A composed of a top plate portion and a skirt portion extending from the periphery of the top plate portion toward the second surface in the axial direction P, and a flange portion 32B formed around the protrusion 32A (skirt portion). Note that the positive electrode terminal 32 does not necessarily have the protrusion 32A or the flange portion 32B. The positive electrode terminal 32 may simply be a conductive flat plate. While the positive electrode terminal 32 is disposed in the center portion of the sealing plate 31, the energy storage device of the present disclosure is not limited to this configuration. In the electricity storage device of the present disclosure, the terminals may be arranged so as to cover the area of ​​the sealing plate that is most susceptible to displacement when the pressure inside the case increases.

[0029] The top surface of the positive electrode terminal 32 may be fixed to the upper surface (second surface) of the sealing plate 31 by the retaining portion, with the top surface not being covered by the retaining portion in the axial direction P (the entire top surface being exposed from the retaining portion). In other words, the positive electrode terminal 32 is fixed by being covered by the retaining portion except for the top surface. More specifically, as shown in FIG. 2 , the inner side surface of the wall portion 31C of the sealing plate 31 abuts against the outer peripheral surface of the flange portion 32B of the positive electrode terminal 32, thereby fixing the positive electrode terminal 32 to the sealing plate 31. In other words, a member for fixing the positive electrode terminal 32 to the sealing plate 31 does not need to be present on the top surface of the positive electrode terminal 32.

[0030] 3 , when an abnormality occurs in the energy storage device 10 and the internal pressure rises, the thin-walled portion 31E deforms preferentially, causing the sealing plate 31 to invert (deform) and bulge upward. When the sealing plate 31 is inverted, the positive electrode terminal 32 is detached from the sealing plate 31 because the top surface of the positive electrode terminal 32 is fixed in an open state, thereby cutting off the electrical connection between the sealing plate 31 and the positive electrode terminal 32. As a result, the reliability of the energy storage device 10 can be improved.

[0031] Here, when the sealing plate 31 is inverted so as to bulge upward, it is preferable that the wall portion 31C opens outward in the radial direction D. Therefore, the wall portion 31C is arranged to surround the region of the sealing plate 31 that is farthest from the electrode body 14 (the center of the sealing plate 31). More specifically, when the sealing plate 31 is inverted so as to bulge upward, it is preferable that the angle (α in FIG. 1 ) formed by the inner circumferential surface of the wall portion 31C and the upper surface of the central portion 31B (the surface extending in the radial direction D) be 90° or greater. This allows the positive electrode terminal 32 to be reliably removed from the sealing plate 31 when the sealing plate 31 is inverted. The wall portion 31C may be cylindrical or may be arranged intermittently in the circumferential direction R. The intermittent wall portion 31C makes it easier to displace the sealing plate 31 compared to a sealing plate 31 having cylindrical wall portions 31C.

[0032] When the positive terminal 32 is fixed to the sealing plate 31, pressure is applied to the wall portion 31C from the outside, thereby crimping and fixing the positive terminal 32 to the wall portion 31C. As a result, the positive terminal 32 is firmly fixed to the sealing plate 31 under normal conditions. The outer peripheral surface of the positive terminal 32 (flange portion 32B) crimped and fixed to the wall portion 31C may be inclined so that its diameter widens toward the second surface of the sealing plate 31. This configuration can restrict displacement of the positive terminal 32 in the axial direction P and the radial direction D when crimped and fixed to the wall portion 31C. Furthermore, when the sealing plate 31 deforms, the wall portion 31C can easily move away from the inclined outer peripheral surface of the positive terminal 32 in the radial direction D. In this case, the inner peripheral surface of the crimped wall portion 31C may be inclined so that the inner diameter of the wall portion widens toward the second surface to match the inclined outer peripheral surface of the positive terminal 32.

[0033] 4, the wall portion 31C and the positive electrode terminal 32 may be fixed by crimping, and the center portion 31B of the sealing plate 31 and the flange portion 32B of the positive electrode terminal 32 may be fixed by welding. However, even when fixed by welding, the positive electrode terminal 32 can be removed from the sealing plate 31 when the sealing plate 31 is turned over. The welding may be spot welding or full-circumference welding. It is not necessary to weld the wall portion 31C and the positive electrode terminal 32 together.

[0034] 1 again, the positive electrode tab 15 is joined to the protruding portion 31D of the sealing plate 31. This allows the sealing plate 31 and the positive electrode 11 to be electrically connected via the positive electrode tab 15. As a result, the number of parts of the energy storage device 10 can be reduced.

[0035] In a conventional energy storage device in which the sealing plate and the positive electrode are electrically connected via a positive electrode tab, if an abnormality occurs in the energy storage device and the internal pressure rises, causing the sealing plate to flip over, the connection between the sealing plate and the positive electrode tab is released, thereby cutting off the electrical connection between the sealing plate and the positive electrode terminal. However, even if the internal pressure rises and the sealing plate flips over, the flexible positive electrode tab may be displaced in response to the deformation of the sealing plate, preventing the connection between the sealing plate and the positive electrode tab from being released, making it impossible to cut off the electrical connection between the sealing plate and the positive electrode terminal.

[0036] According to the energy storage device 10 of this embodiment, even if the internal pressure rises and the sealing plate 31 inverts, causing the positive electrode tab 15 to stretch and preventing the sealing plate 31 from being separated from the positive electrode tab 15 (regardless of whether the sealing plate 31 and the positive electrode tab 15 separate), the positive electrode terminal 32 can be removed from the sealing plate 31, and the current flowing from the sealing plate 31 to the positive electrode terminal 32 can be interrupted. This further improves the reliability of the energy storage device 10.

[0037] As described above, when an abnormality occurs in the energy storage device 10 and the internal pressure rises, the thin portion 31E of the sealing plate 31 inverts, the positive electrode terminal 32 is detached from the sealing plate 31, and the sealing plate 31 and the positive electrode terminal 32 are electrically disconnected from each other. If the internal pressure of the energy storage device 10 rises further after the above-mentioned disconnection, the thin portion 31E breaks preferentially, forming a gas exhaust port in the sealing plate 31. This can further improve the reliability of the energy storage device 10.

[0038] Gasket 33 is a rubber or resin member that prevents contact between case 20 and sealing plate 31 and ensures electrical insulation between case 20 and sealing plate 31. Gasket 33 also seals the gap between case 20 and sealing plate 31, sealing the inside of power storage device 10.

[0039] The insulating member 34 is disposed below the sealing plate 31. A through-hole is formed in the center of the insulating member 34, and the protrusion 31D of the sealing plate 31 engages with the through-hole. The insulating member 34 also has a plurality of openings formed therein for allowing gas to escape when the internal pressure increases. The insulating member 34 may be formed integrally with the gasket 33.

[0040] 5 to 8 , a description will be given of a power storage module 60 including a power storage device 40 as another example of an embodiment and a power storage device 50 as another example of an embodiment. Note that, hereinafter, only configurations that differ from the above-described power storage device 10 will be described, and configurations that are similar to those of the power storage device 10 will be omitted or simply described using the same reference numerals.

[0041] 5, the energy storage device 40 includes an electrode assembly 14 in which a positive electrode 11 and a negative electrode 12 are wound with a separator 13 interposed therebetween, a case 20 that houses the electrode assembly 14, and a sealing body 30 that closes the opening of the case 20. The case 20 houses an electrolyte solution together with the electrode assembly 14. The sealing body 30 is provided with a sealing plate 31 that is electrically connected to the positive electrode 11, and a positive electrode terminal 32 that is fixed to the upper surface of the sealing plate 31 with the upper side open.

[0042] A spring 35 serving as an elastic member and serving as an example of a spacer is disposed between the sealing plate 31 and the positive electrode terminal 32. The spring 35 is disposed between the sealing plate 31 and the positive electrode terminal 32 in a state in which the spring 35 biases the positive electrode terminal 32 in a direction in which the positive electrode terminal 32 is removed from the sealing plate 31 (e.g., in the axial direction P) (in a state in which the spring 35 is compressed by the positive electrode terminal 32 and the sealing plate 31). The spring 35 is preferably made of an electrically insulating material such as resin or ceramic. Alternatively, a block-shaped rubber body may be disposed instead of the spring 35.

[0043] As shown in FIGS. 6 and 7 , instead of a spring, an insulating member 36 may be disposed on the surface of the region of the sealing plate 31 surrounded by the holding portion as a spacer. A protrusion 37 may be formed in the region surrounded by the holding portion, closer to the region of the sealing plate 31 that is most susceptible to deformation than the holding portion, to electrically insulate the positive electrode terminal 32 from the sealing plate 31. Providing this protrusion 37 makes it easier for the sealing plate 31 to protrude from the holding portion in the axial direction P after the sealing plate 31 is inverted, thereby preventing re-conduction between the positive electrode terminal 32 and the sealing plate 31. The insulating member 36 can be formed by oxidizing the surface of the sealing plate 31, attaching an insulating sheet, or applying an insulating material. Examples of insulating sheets include polyimide tape. Examples of applied insulating materials include silicone adhesives.

[0044] According to the energy storage device 40 of this embodiment, if an abnormality occurs in the energy storage device 40 and the internal pressure rises, causing the sealing plate 31 to flip over, the positive electrode terminal 32 can be detached from the sealing plate 31 as described above. At this time, the spring 35 is disposed between the sealing plate 31 and the positive electrode terminal 32, which prevents the detached positive electrode terminal 32 from coming into contact with the sealing plate 31. This reliably cuts off the electrical connection between the sealing plate 31 and the positive electrode terminal 32. As a result, the reliability of the energy storage device 40 can be further improved.

[0045] As shown in FIG. 8 , the energy storage module 60 includes a plurality of energy storage devices 50, a positive electrode current collector (not shown) on which a positive electrode lead 61 connected to the positive electrode terminal 32 of the energy storage device 50 is formed, and a negative electrode current collector (not shown) on which a negative electrode lead (not shown) connected to the case 20 of the energy storage device 50 is formed.

[0046] The multiple power storage devices 50 may be packed as densely as possible within the power storage module 60, taking safety into consideration, and adjacent power storage devices 50 may be arranged in close proximity to each other. In the power storage module 60, for example, in a plan view, one power storage device 50 may be arranged so that six power storage devices 50 surround it (or arranged in a staggered pattern). The multiple power storage devices 50 are connected to each other in parallel or in series via current collector plates (bus bars).

[0047] The positive electrode lead 61 is provided on the current collector plate and joined by welding to the positive electrode terminal 32. The positive electrode lead 61 is an elastic member and joined by welding to the positive electrode terminal 32 in a state in which the positive electrode terminal 32 is biased in a direction in which the positive electrode terminal 32 is removed from the sealing plate 31.

[0048] According to the energy storage device 50 of this embodiment, if an abnormality occurs in the energy storage device 50 and the internal pressure rises, causing the sealing plate 31 to flip over, the positive electrode terminal 32 will come off the sealing plate 31 (retaining portion) as described above. At this time, the biasing force of the positive electrode lead 61 moves the positive electrode terminal 32 that has come off the sealing plate 31 away from the sealing plate 31, preventing it from coming into contact with the sealing plate 31. This reliably cuts off the electrical connection between the sealing plate 31 and the positive electrode terminal 32. As a result, the reliability of the energy storage device 10 can be further improved.

[0049] It should be noted that the present disclosure is not limited to the above-described embodiments and their variations, and it goes without saying that various modifications and improvements are possible within the scope of the matters described in the claims of the present application.

[0050] 10, 40, 50 Energy storage device, 11 Positive electrode (first electrode), 12 Negative electrode (second electrode), 13 Separator, 14 Electrode body, 15 Positive electrode tab, 16 Upper insulating plate, 20 Case, 20A Cylindrical portion, 20B Bottom portion, 20C Shoulder portion, 20D Groove portion, 30 Sealing body, 31 Sealing plate, 31A Outer periphery, 31B Central portion, 31C Wall portion (holding portion), 31D Convex portion, 31E Thin portion, 32 Positive electrode terminal (terminal), 32A Convex portion, 32B Flange portion, 33 Gasket, 34 Insulating member, 35 Spring (spacer portion), 36 Insulating member, 37 Protrusion, 60 Energy storage module, 61 Positive electrode lead

Claims

1. An electrode body including a first electrode and a second electrode, A case for housing the electrode body, A sealing body that closes the opening of the aforementioned case, Equipped with, The sealing body includes a sealing plate electrically connected to the first electrode, and a terminal disposed on the sealing plate and electrically connected to the sealing plate. The sealing plate has a first surface facing the electrode body and a second surface located on the opposite side in the axial direction from the first surface. The terminals are arranged on the second surface, The sealing plate deforms in the axial direction away from the electrode body when the pressure inside the case increases. The second surface of the sealing plate has a holding portion formed thereon that covers the outer circumferential surface of the terminal and holds the terminal. Energy storage device.

2. The energy storage device according to claim 1, The retaining portion includes a wall portion that protrudes outward in the axial direction from the second surface of the sealing plate, The outer surface of the terminal and the wall portion are in contact. Energy storage device.

3. The energy storage device according to claim 1, The terminal is positioned in the sealing plate such that it overlaps with the region furthest from the electrode body when the pressure inside the case increases. The holding portion is arranged to surround the area. Energy storage device.

4. The energy storage device according to claim 3, The outer surface of the terminal is inclined to widen as it approaches the second surface in the axial direction. In the terminal, the entire back surface of the surface facing the second surface is exposed from the holding portion. Energy storage device.

5. The energy storage device according to claim 4, The terminal and the sealing plate are joined by welding. Energy storage device.

6. A power storage device according to any one of claims 2 to 5, The outer surface of the terminal has a flange portion, The radial end faces of the flange portion are formed inclined so as to widen from one side to the other in the axial direction. Energy storage device.

7. A power storage device according to any one of claims 1 to 6, In the axial direction, a gap is formed between the terminal and the second surface. An elastic body, electrically insulated from the terminal, is placed in the gap in a state of being compressed in the axial direction. Energy storage device.

8. A power storage device according to any one of claims 3 to 5, In the axial direction, a gap is formed between the terminal and the second surface. On the second surface, a protrusion is formed closer to the region than the holding portion. The projection is electrically insulated from the terminal. Energy storage device.

9. A power storage device according to any one of claims 1 to 8, The terminal has a top plate portion and a skirt portion that extends from the periphery of the top plate portion toward the second surface in the axial direction. Energy storage device.