Energy storage element

Abstract

This energy storage element comprises: a container; cell terminals provided outside the container; an electrode assembly housed in the container and having an electrode assembly body and a tab bundle; and current collectors 600 connecting the cell terminals and the electrode assembly body. Each current collector 600 has a terminal connection part 602, an electrode connection part 603 connected to the electrode assembly in a first direction, and an intermediate part 604 connecting the terminal connection part 602 and the electrode connection part 603. The intermediate part 604 is disposed in a position overlapping with the terminal connection part 602 when viewed from the first direction. The electrode connection part 603 is disposed closer to one side than the intermediate part 604 in the first direction. The electrode connection part has a first surface that faces the electrode assembly and a second surface 603b opposite to the first surface, and the tab bundle is joined to the second surface 603b.

Description

Energy storage element

[0001] The present invention relates to an energy storage element including a cell terminal, an electrode assembly, and a current collector connecting the cell terminal and the electrode assembly.

[0002] Patent Literature 1 discloses an energy storage element in which a current collector is housed in a container together with an electrode assembly. The electrode connection portion of the current collector, to which the tab bundle of the electrode assembly is connected, is arranged in the container so as to be close to the cell terminal outside the container. This configuration makes it possible to reduce the distance between the current collector and the terminal of the energy storage element, allowing a larger electrode assembly to be housed in the container, thereby improving energy density.

[0003] WO2022 / 071516 publication

[0004] One embodiment of the present invention provides an energy storage element that is easy to assemble and has high energy density.

[0005] An energy storage device according to one aspect of the present invention includes a container, a cell terminal provided outside the container, an electrode assembly housed in the container and having an electrode assembly main body and a tab bundle, and a current collector connecting the cell terminal and the electrode assembly. The current collector has a terminal connection portion, an electrode connection portion connected to the electrode assembly in a first direction, and an intermediate portion connecting the terminal connection portion and the electrode connection portion. The intermediate portion is positioned so as to overlap the terminal connection portion when viewed from the first direction, the electrode connection portion is positioned to one side of the intermediate portion in the first direction, and the tab bundle is joined to a second surface of the electrode connection portion opposite a first surface facing the electrode assembly main body.

[0006] The present invention can be realized not only as an electricity storage element, but also as a current collector, and a method for manufacturing an electricity storage element or a current collector.

[0007] According to one embodiment of the present invention, an energy storage element which is easy to assemble and has high energy density can be provided.

[0008] FIG. 1 is a perspective view showing the appearance of an energy storage element according to an embodiment; FIG. 2 is an exploded perspective view showing each component of the energy storage element; FIG. 3 is a perspective view and a front view showing the configuration of a positive electrode current collector according to an embodiment; FIG. 4 is a cross-sectional view comparing a case where a tab bundle is joined to a first surface of an electrode connection part and a case where the tab bundle is joined to a second surface of the electrode connection part; FIG. 5 is a perspective view and a front view showing a modified example of a positive electrode current collector; FIG. 6 is a diagram illustrating the bending direction of a connection part of a current collector and the bending direction of a tab bundle; FIG. 7 is a diagram illustrating the bending direction of a connection part of a current collector and the bending direction of a tab bundle; and FIG. 8 is a front view showing a modified example of a positive electrode current collector.

[0009] The following provides an overview of embodiments (1) and (2) of the present invention. (1) An energy storage element includes a container, a cell terminal provided outside the container, an electrode assembly housed in the container and having an electrode assembly main body and a tab bundle, and a current collector connecting the cell terminal and the electrode assembly. The current collector has a terminal connection portion, an electrode connection portion connected to the electrode assembly in a first direction, and an intermediate portion connecting the terminal connection portion and the electrode connection portion. The intermediate portion is positioned so as to overlap the terminal connection portion when viewed from the first direction, and the electrode connection portion is positioned to one side of the intermediate portion in the first direction, and the tab bundle is joined to a second surface of the electrode connection portion opposite a first surface facing the electrode assembly main body.

[0010] According to the above configuration (1), the radius of curvature of the tab bundle that curves inside the container can be made larger than when the tab bundle is joined to the first surface of the electrode connection portion, which reduces the stress that occurs in the tab bundle when bending the tab bundle, thereby reducing the difficulty and defect rate of the process of bending the tab bundle and improving the ease of assembly of the energy storage element.

[0011] In recent years, in order to improve the energy density of energy storage devices, the electrode body of an energy storage device has been increasing the number of stacked positive and negative electrode plates, resulting in a very large number of stacked tabs forming a tab bundle. When a tab bundle made up of such a large number of tabs is bent, stress acts on the tip of the tab bundle where it is joined to the current collector, tending to misalign adjacent tabs. This is because, with a large number of stacked tabs, the radius of curvature of the outermost tabs in the tab bundle becomes smaller and they are pulled more strongly. This tendency becomes more pronounced when the tab bundle is bent more sharply. According to the above-mentioned configuration (1), by joining the tab bundle to the surface (second surface) of the current collector opposite the surface (first surface) facing the electrode body main body, the bending of the tab bundle within the container can be made gentler, thereby reducing stress on the tab bundle and the incidence of defects.

[0012] (2) In the energy storage element of (1) above, the current collector may have a notch in the electrode connection portion that allows the tab bundle to pass from the first surface toward the second surface.

[0013] According to the above configuration (2), the tab bundle can be more gently curved inside the container, thereby reducing stress on the tab bundle and the incidence of defects. In addition, the tab bundle can reach the second surface of the electrode connection portion in a shorter distance, thereby reducing the electrical resistance of the tab bundle.

[0014] [1 General Description of Energy Storage Device] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a perspective view showing the appearance of an energy storage device 10 according to this embodiment. Fig. 2 is an exploded perspective view showing the components of the energy storage device 10.

[0015] The energy storage element 10 is a secondary battery that can charge and discharge electricity, specifically a nonaqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is used, for example, as a drive or auxiliary battery for automobiles such as electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), motorcycles, or other mobile vehicles. The energy storage element 10 may also be used in stationary storage battery facilities such as energy storage systems (ESS), rapid charging systems for EVs, and backup power supply systems.

[0016] The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than a non-aqueous electrolyte secondary battery, a capacitor, a primary battery, or a battery using a solid electrolyte.

[0017] 1 , the energy storage element 10 includes a container 100, a positive terminal 200 and a negative terminal 210 provided outside the container 100, and upper gaskets 300 and 310. Tips of shaft portions 601 and 611, which will be described later, may be exposed on the upper surfaces of the positive terminal 200 and the negative terminal 210.

[0018] 2 , the container 100 contains lower gaskets 400 and 500, a positive electrode current collector 600, a negative electrode current collector 610, and an electrode assembly 700. An electrolytic solution (non-aqueous electrolyte) is sealed inside the container 100. In addition to the above components, spacers disposed on the sides, above, or below the electrode assembly 700, an insulating film encasing the electrode assembly 700, and the like may also be provided.

[0019] The container 100 is a rectangular parallelepiped case made up of a container body 110 that is a rectangular cylinder with a bottom, and a lid 120 that is a plate-like member that closes the opening of the container body 110. After the electrode assembly 700 and other components are housed inside the container 100, the container body 110 and the lid 120 are fixed together by welding or the like to seal the interior. The material of the container 100 is not particularly limited, but is preferably a weldable metal such as stainless steel, aluminum, an aluminum alloy, iron, or plated steel sheet.

[0020] The lid 120 is provided with a gas exhaust valve 121 that exhausts gas from the inside of the container 100 when the internal pressure of the container 100 increases. The container 100 may be formed with a liquid injection part for injecting an electrolyte solution therein.

[0021] The electrode assembly 700 is an electricity storage element (power generation element) that includes a positive electrode plate, a negative electrode plate, and a separator and can store electricity. The positive electrode plate has a flat, rectangular positive electrode current collector foil made of aluminum or an aluminum alloy, etc., and a positive electrode active material layer formed on the surface of the positive electrode current collector foil. The negative electrode plate has a flat, rectangular negative electrode current collector foil made of copper or a copper alloy, etc., and a negative electrode active material layer formed on the surface of the negative electrode current collector foil. Any known material can be used as the positive electrode active material and the negative electrode active material, as long as they are active materials that can absorb and release lithium ions.

[0022] Both the positive electrode current collector foil and the negative electrode current collector foil have rectangular tabs that protrude in the Z-axis direction toward the lid 120. By stacking multiple positive electrode plates and multiple negative electrode plates with separators sandwiched between them, multiple tabs are stacked on both the positive electrode plates and the negative electrode plates. As a result, the electrode assembly 700 has an electrode assembly main body 700a that is rectangular in front view, and a positive electrode tab bundle 710 and a negative electrode tab bundle 720 that protrude therefrom.

[0023] The shapes of the positive and negative electrode plates are not limited to a rectangular shape, and may be polygonal shapes other than a rectangular shape, elongated ellipsoidal shapes, oval shapes, etc. The tabs of the positive and negative electrode plates are also not limited to a rectangular shape, and may be polygonal shapes other than a rectangular shape, semicircular shapes, semi-oval shapes, semi-oval shapes, etc.

[0024] The positive terminal 200 is a cell terminal electrically connected to the positive electrode plate of the electrode assembly 700 via the positive electrode current collector 600. The negative terminal 210 is a cell terminal electrically connected to the negative electrode plate of the electrode assembly 700 via the negative electrode current collector 610. The positive terminal 200 and the negative terminal 210 are metal terminals for conducting electricity stored in the electrode assembly 700 to the external space of the energy storage element 10 and for introducing electricity into the internal space of the energy storage element 10 in order to store electricity in the electrode assembly 700. As will be described later, the positive terminal 200 and the negative terminal 210 are connected to the positive electrode current collector 600 and the negative electrode current collector 610 from the outside of the container by crimping or the like, and are fixed to the lid 120.

[0025] The positive electrode current collector 600 is a conductive member that electrically connects the positive electrode plate of the electrode assembly 700 to the positive terminal 200. The negative electrode current collector 610 is a conductive member that electrically connects the negative electrode plate of the electrode assembly 700 to the negative terminal 210. The positive electrode current collector 600 is joined to the positive electrode tab bundle 710 of the electrode assembly 700 by welding or the like, and is also joined to the positive terminal 200 by crimping or the like. The negative electrode current collector 610 is joined to the negative electrode tab bundle 720 of the electrode assembly 700 by welding or the like, and is also joined to the negative terminal 210 by crimping or the like. The positive electrode current collector 600 is formed of aluminum or an aluminum alloy or the like, and the negative electrode current collector 610 is formed of copper or a copper alloy or the like.

[0026] The positive electrode current collector 600 and the negative electrode current collector 610 are disposed between the electrode assembly 700 and the lid 120. Specifically, the positive electrode current collector 600 is disposed between the positive electrode tab bundle 710 of the electrode assembly 700 and the lower gasket 400, and the negative electrode current collector 610 is disposed between the negative electrode tab bundle 720 of the electrode assembly 700 and the lower gasket 500. Details of the configurations of the positive electrode current collector 600 and the negative electrode current collector 610 will be described later.

[0027] The upper gasket 300 is a flat insulating sealing member disposed between the cover 120 and the positive terminal 200. The upper gasket 310 is a flat insulating sealing member disposed between the cover 120 and the negative terminal 210.

[0028] The lower gasket 400 is a flat insulating sealing member disposed between the lid 120 and the positive electrode current collector 600. The lower gasket 500 is a flat insulating sealing member disposed between the lid 120 and the negative electrode current collector 610.

[0029] [2. Description of the Configuration of the Positive Electrode Current Collector and the Negative Electrode Current Collector] Next, a detailed description will be given of the configurations of the positive electrode current collector 600 and the negative electrode current collector 610. The positive electrode current collector 600 and the negative electrode current collector 610 have the same configuration (shapes symmetrical with respect to the YZ plane passing through the center point of the battery), and therefore, the following will describe the positive electrode current collector 600 in detail, and a description of the negative electrode current collector 610 will be simplified or omitted.

[0030] As shown in FIG. 2 , the positive electrode current collector 600 has a shaft portion 601 that protrudes in the Z-axis direction (first direction) toward the lid 120. The shaft portion 601 passes through a hole 401 provided in the lower gasket 400, a hole 123 provided in the lid 120, and a hole 301 provided in the upper gasket 300. The tip of the shaft portion 601 is inserted into the through-hole 201 provided in the positive terminal 201 and is then crimped from the outside (from above the lid 120). As a result, the positive terminal 200 is fixed to the lid 120 together with the upper gasket 300, the lower gasket 400, and the positive electrode current collector 600. The same applies to the negative electrode side. The positive terminal 200 and the negative terminal 210 are formed of aluminum, an aluminum alloy, copper, a copper alloy, or the like.

[0031] The shaft portion 601 is integrated with the positive electrode current collector 600 rather than the positive terminal 200, and the shaft portion 601 can be mechanically joined to the positive terminal 200 from the outside of the lid 120 by crimping or the like. This reduces the possibility that foreign matter such as metal powder, which may be generated when mechanically joining the shaft portion 601 to the positive terminal 200, will get into the container 100. Since the shaft portion 601 can be easily connected to the positive terminal 200, the assembly of the energy storage element 10 is improved. There is also a high degree of freedom regarding the timing of connecting the shaft portion 601 to the positive terminal 200.

[0032] 3A and 3B are a perspective view and a front view showing the configuration of the positive electrode current collector 600 according to this embodiment, in which (a) is a perspective view of the positive electrode current collector 600 seen from diagonally above, and (b) is a front view of the positive electrode current collector 600 of (a) seen from the negative side in the Y-axis direction.

[0033] 3 , the positive electrode current collector 600 has a terminal connection portion 602 provided with a shaft portion 601 and connected to the positive terminal 200, an electrode connection portion 603 connected to the electrode body 700, and an intermediate portion 604 disposed between the terminal connection portion 602 and the electrode connection portion 603. In other words, a single L-shaped flat plate member is bent to form the positive electrode current collector 600 having the terminal connection portion 602, the intermediate portion 604, and the electrode connection portion 603. The intermediate portion 604 can also be considered as part of the electrode connection portion 603.

[0034] The terminal connection portion 602 is a rectangular, flat portion disposed parallel to the XY plane. The shaft portion 601 is formed integrally with the terminal connection portion 602 and protrudes from a terminal connection portion second surface (surface facing the lid 120) 602b toward the positive side in the Z axis direction. The tip of the shaft portion 601 may be hemispherical or planar, and may have a guide recess for guiding a crimping jig (not shown). The method for connecting (joining) the shaft portion 601 and the positive terminal 200 is not limited to crimping; welding such as ultrasonic welding, laser welding, or resistance welding, or mechanical joining other than crimping, such as screw fastening, may also be used.

[0035] The electrode connection portion 603 is a rectangular, flat portion connected (joined) to the tab bundle 710 of the electrode body 700 by welding or the like, and is disposed parallel to the XY plane. As will be described later, the tab bundle 710 of the electrode body 700 (see FIG. 2 ) is joined by welding to the electrode connection portion second surface 603b (the surface opposite to the electrode body main body 700a). In this way, the electrode connection portion 603 is joined to the tab bundle 710 of the electrode body 700 in the Z-axis direction (first direction).

[0036] The intermediate portion 604 is a generally rectangular and generally flat portion that connects the terminal connection portion 602 and the electrode connection portion 603, and is disposed parallel to the XY plane. The intermediate portion 604 is disposed on the negative side of the terminal connection portion 602 in the Z axis direction and on the negative side of the electrode connection portion 603 in the X axis direction. In other words, the intermediate portion 604 is disposed at a position that overlaps with the terminal connection portion 602 when viewed from the Z axis direction (first direction), and is disposed side by side with the electrode connection portion 603 in the X axis direction. The intermediate portion 604 has a connection portion 605 with the terminal connection portion 602 and a connection portion 606 with the electrode connection portion 603.

[0037] The connection portion 605 is connected to the end portion of the terminal connection portion 602 on the positive side in the Y axis direction, and is curved so as to be convex on the positive side in the Y axis direction, so that the cross section of the connection portion 605 in the YZ plane is U-shaped. The connection portion 605 may be a bent portion rather than curved.

[0038] The connection portion 606 is connected to the end of the electrode connection portion 603 on the negative X-axis direction, and is a portion that is inclined toward the negative Z-axis direction toward the negative X-axis direction, so that its cross-sectional shape in the XZ plane is approximately S-shaped. In other words, the connection portion 606 is an inclined portion formed by bending the intermediate portion 604 toward the negative Z-axis direction and then toward the negative X-axis direction with respect to the electrode connection portion 603. As a result, the intermediate portion 604 is positioned on the negative X-axis direction and the negative Z-axis direction of the electrode connection portion 603.

[0039] [3. Explanation of Connection of Tab Bundle to Current Collector] FIG. 4 is a cross-sectional view (cross-sectional view taken along line IV-IV in FIG. 3) comparing (a) a case where the tab bundle is joined to the first surface of the electrode connection portion with (b) a case where the tab bundle is joined to the second surface of the electrode connection portion. To improve energy density, the electrode body main body 700a occupies the internal space of the container body 110 up to the vicinity of the cover plate 120. Furthermore, the electrode body main body 700a has a large number of stacked positive and negative electrode plates, resulting in a large thickness dimension. Multiple tabs protruding from different positions in the thickness direction of the electrode body main body 700a toward the cover 120 are bundled together to form a tab bundle 710. A portion 710a near the tip of the tab bundle 710 is joined to the electrode connection portion 603 by ultrasonic welding or the like. Thereafter, the tab bundle 710 is curved within the container body 110 so as to be parallel to the electrode connection portion 603 which is parallel to the lid body 120 (to the state shown in FIG. 4( a ) or FIG. 4( b )).

[0040] 4(a), when the tab bundle 710 is joined to the first surface 603a of the electrode connection portion 603, the tab extending from the positive electrode plate on the left side in the figure is bent with a particularly small radius of curvature, and a strong tensile force acts on the joint portion 710a on the tip side, which may cause problems such as partial separation of the joint portion 710a of the tab bundle 710 from the electrode connection portion 603 or high electrical resistance at the joint portion 710a.

[0041] Therefore, in this embodiment, as shown in FIG. 4( b), the joint 710a at the tip end of the tab bundle 710 is joined to the second surface 603b of the electrode connection portion 603. This allows the tab bundle 710 to bend more gently within the container body 110, reducing stress on the tab bundle 710 and thereby reducing the incidence of defects. The configuration shown in FIG. 4( b) also allows an electrode body 700a with a larger height to be housed within the container body 110, thereby further improving energy density. Although not shown, an insulating plate (spacer) extending parallel to the electrode connection portion 603 may be inserted between the electrode connection portion 603 in FIG. 4( b) and the tabs protruding from the electrode body 700a to prevent the tab bundle 710 from contacting the electrode connection portion 603 at unintended locations other than the joint 710a at the tip end.

[0042] 5 shows a modified example of a positive electrode current collector. In this positive electrode current collector 600a, a notch 603c is provided in the electrode connection portion 603 so as to narrow the dimension in the Y-axis direction (width direction). The notched portion and the non-notched portion are connected by an inclined surface 603d. In this example, two notches 603c, 603c are provided on both sides of the electrode connection portion 603 in the Y-axis direction, but a notch 603Cc may be provided on only one side through which the tab bundle 710 (see FIG. 4B) passes.

[0043] 5, the curvature of the tab bundle 710 inside the container 100 can be made gentler, reducing stress on the tab bundle 710 and the incidence of defects. Furthermore, by passing the tab bundle 710 through the notch 603c, the tab bundle 710 can reach the second surface 603b of the electrode connection portion in a shorter distance. This shortens the current path, reducing the electrical resistance in the tab bundle 710.

[0044] [4 Description of Effects] According to this embodiment, the terminal connection portion 602 and the electrode connection portion 603 are arranged on one side of the intermediate portion 604 in the first direction (Z-axis direction). This allows the electrode body 700 to be closer to the cell terminals 200, 210 in the first direction, and allows a larger electrode body 700 to be arranged in the height direction. This allows the energy density of the energy storage element 10 to be improved.

[0045] According to this embodiment, by joining the tab bundles 710, 720 to the second surface of the current collectors 600, 610 opposite the first surface facing the electrode body main body 700a, the curvature of the tab bundles 710, 720 within the container 100 can be made gentler, thereby reducing the stress generated in the tab bundles 710, 720 and reducing the rate of occurrence of defects.

[0046] 5, by providing a notch in the electrode connection portion that allows the tab bundles 710, 720 to pass from the first surface to the second surface, the curvature of the tab bundles 710, 720 can be made gentler inside the container 100. In addition, the tab bundles 710, 720 can reach the second surface of the electrode connection portion over a shorter distance, thereby reducing the electrical resistance of the conductive path.

[0047] 6 , the bending direction of the connection portion 605 of the positive electrode current collector 600 is opposite to the bending direction of the tab bundle 710, the tip of which is joined to the second surface 603b of the electrode connection portion. The connection portion 605 is connected to the end of the terminal connection portion 602 on the positive side in the Y axis direction, and is curved so as to be convex on the positive side in the Y axis direction (its cross section in the YZ plane is U-shaped). The tab bundle 710 is curved so as to be convex on the negative side in the Y axis direction.

[0048] Consider a case in which an L-shaped current collector fixed to a lid is bent so that its middle portion overlaps the terminal connection portion, as in the aforementioned Patent Document 1 (WO 2022 / 071516, see FIG. 4 ). If the bending direction of the connection portion 605 and the bending direction of the tab bundle 710, whose tip end portion is joined to the second surface 603 b of the electrode connection portion, are opposite, a space can be secured around the L-shaped current collector when it is bent, as shown in FIG. 7( a). If the bending direction of the connection portion 605 and the bending direction of the tab bundle 710, whose tip end portion is joined to the second surface 603 b of the electrode connection portion, are the same, the tip end portion of the tab bundle 710 must pass through a narrow gap, as shown in FIG. 7( b), making assembly cumbersome.

[0049] 5, a notch is provided at the end of the electrode connection portion 603 in the Y-axis direction (width direction), but a notch (slit) may be provided inside the electrode connection portion 603 (at the position inside the outline in plan view).

[0050] The electrode body 700 may be a wound type (for example, a horizontally wound type in which the winding center line is parallel to the Z-axis direction) instead of the stacked type shown in FIG.

[0051] As shown in FIG. 8 , a shaft portion 601 separate from the terminal connection portion 602 may be used. The shaft portion 601 shown in FIG. 4 has a rivet portion 601a and a flat flange portion 601b. The area of ​​the flange portion 601b as viewed in the Z-axis direction (cross-sectional area in the XY plane) is larger than that of the rivet portion 601a. ​​The flange portion 601b may be disk-shaped or rectangular plate-shaped. The flange portion 601b is disposed in the gap in the Z-axis direction between the terminal connection portion first surface 602a and the intermediate portion 604. The rivet portion 601a passes through a hole provided in the terminal connection portion 602 and protrudes toward the lid.

[0052] 2, 3, and 5, the positive electrode current collector 600 and the negative electrode current collector 610 are bent at the connection portion 606, which is the boundary between the intermediate portion 604 and the electrode connection portion 603, and the electrode connection portion 603 is disposed on the positive side of the Z axis direction relative to the intermediate portion 604, but this is not limiting. As shown in Fig. 8, the intermediate portion 604 and the electrode connection portion 603 may be disposed on the same plane (XY plane), or the connection portion 606 may be bent so that the electrode connection portion 603 is disposed on the negative side of the Z axis direction relative to the intermediate portion 604.

[0053] REFERENCE SIGNS LIST 10 Energy storage element 100 Container 200 Positive terminal (cell terminal) 600 Positive electrode current collector (current collector) 602 Terminal connection portion 603 Electrode connection portion 603a First surface 603b Second surface 603c Notch 604 Intermediate portion 700 Electrode body 700a Electrode body main body 710, 720 Tab bundle

Claims

1. An energy storage element comprising: a container; a cell terminal provided outside the container; an electrode assembly having an electrode assembly main body and a tab bundle housed in the container; and a current collector connecting the cell terminal and the electrode assembly, wherein the current collector has a terminal connection portion, an electrode connection portion connected to the electrode assembly in a first direction, and an intermediate portion connecting the terminal connection portion and the electrode connection portion, the intermediate portion being positioned at a position overlapping the terminal connection portion when viewed from the first direction, the electrode connection portion being positioned to one side of the intermediate portion in the first direction, and the tab bundle being joined to a second surface of the electrode connection portion opposite a first surface facing the electrode assembly main body.

2. The energy storage element according to claim 1, wherein the current collector has a notch at the electrode connection portion that allows the tab bundle to pass from the first surface toward the second surface.

3. The energy storage element according to claim 1 or 2, wherein the current collector has a connection portion that connects the terminal connection portion and the intermediate portion, and the connection portion and the tab bundle are curved convexly in opposite directions.

Images