Power storage element

Abstract

This power storage element comprises a container, a cell terminal that is provided to the exterior of the container, an electrode body that is housed in the container, and a current collector 600 that connects the cell terminal and the electrode body. The current collector 600 has a terminal connection section 602, a shaft section 601 that protrudes in a first direction from the terminal connection section 602 and is connected to the cell terminal, and an electrode connection section 603 that is located on the opposite side of the terminal connection section 602 from the side where the shaft section 601 protrudes, and is connected to the electrode body in the first direction. The electrode connection section 603 is connected to the terminal connection section 602 via a connection section 605 extending from the terminal connection section 602 to said opposite side, and partially faces the terminal connection section 602 as viewed in the first direction.

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 electrode assembly and the terminal of the energy storage element, allowing a larger electrode assembly to be housed in the container, thereby improving energy density.

[0003] WO2020 / 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 a current collector connecting the cell terminal and the electrode assembly. The current collector has a terminal connection portion, a shaft portion protruding from the terminal connection portion in a first direction and connected to the cell terminal, and an electrode connection portion located on the side of the terminal connection portion opposite the side from which the shaft portion protrudes and connected to the electrode assembly in the first direction. The electrode connection portion is connected to the terminal connection portion via a connection portion extending from the terminal connection portion in the opposite direction and partially faces the terminal connection portion as viewed in the first direction. Preferably, the portion of the electrode connection portion to which the electrode assembly is connected does not face the terminal connection portion as viewed in the first direction. For example, the current collector can be manufactured by bending a conductive component having an L-shape in plan view, with the shaft portion protruding from its surface, into an I-shape in plan view (by bending at the base (corresponding to the connection portion) of the straight portion on which the shaft portion is formed, of the two straight portions forming the L shape).

[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 front view showing a modified example of a positive electrode current collector; FIG. 5 is a front view showing a modified example of a positive electrode current collector; FIG. 6 is a cross-sectional view showing a connection configuration between a shaft portion of a positive electrode current collector and a cell terminal (positive terminal); FIG. 7 is a cross-sectional view showing a modified example of a connection configuration between a shaft portion of a positive electrode current collector and a cell terminal; FIG. 8 is a cross-sectional view showing a modified example of a connection configuration between a shaft portion of a positive electrode current collector and a cell terminal.

[0009] The following provides an overview of embodiments (1) and (2) of the present invention. (1) 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 a current collector connecting the cell terminal and the electrode assembly. The current collector has a terminal connection portion, a shaft portion protruding from the terminal connection portion in a first direction and connected to the cell terminal, and an electrode connection portion located on the side of the terminal connection portion opposite the side from which the shaft portion protrudes and connected to the electrode assembly in the first direction. The electrode connection portion is connected to the terminal connection portion via a connection portion extending from the terminal connection portion to the opposite side and partially faces the terminal connection portion as viewed in the first direction. The portion of the electrode connection portion to which the electrode assembly is connected does not face the terminal connection portion as viewed in the first direction.

[0010] According to the configuration (1) above, the shaft portion connected to the cell terminal protrudes from the current collector, and the shaft portion can be mechanically joined to the cell terminal from the outside of the lid by crimping or the like. This reduces the possibility that foreign matter such as metal powder that may be generated when mechanically joining the shaft portion to the cell terminal will enter the inside of the container. Compared to joining the shaft portion inside the lid by crimping or the like, this reduces the occurrence of defects due to the intrusion of foreign matter, and the shaft portion can be easily connected to the cell terminal, improving the assembly ease of the energy storage element.

[0011] Furthermore, the configuration (1) above provides a high degree of freedom in the timing of mechanically joining the shank to the cell terminal. When the shank (rivet portion) provided on the cell terminal and protruding toward the inside of the container is crimped to the inside of the container lid, as in Patent Document 1, after the crimping, it is necessary to fold the L-shaped current collector fixed to the lid and position the middle portion so that it overlaps with the terminal connection portion (see Figure 4 of Patent Document 1). This manufacturing method may reduce the airtightness of the upper and lower gaskets sandwiched between the cell terminal and the current collector when the current collector is bent. In contrast, the configuration (1) above allows the shank to be mechanically joined to the cell terminal from outside the lid after the current collector is bent, that is, after the electrode connection portion (middle portion) is positioned so that it overlaps with the terminal connection portion (see Figure 3 of the present application). This provides a high degree of freedom in the timing of joining the shank to the cell terminal, further improving the ease of assembly of the energy storage element.

[0012] (2) In the energy storage element of (1) above, the shaft portion may be configured as a separate body having a flange portion and a rivet portion that protrudes from the flange portion and penetrates the terminal connection portion, and the flange portion may be disposed in a gap between the terminal connection portion and the electrode connection portion (see Figures 4 and 5 of the present application).

[0013] According to the above-mentioned configuration (2), the current collector can be easily molded, and the freedom of material selection is increased. Furthermore, since the flange portion has a predetermined area, the flange portion can be easily and firmly fixed to the terminal connection portion.

[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 is formed with a positive electrode tab bundle 710 and a negative electrode tab bundle 720.

[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. 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 and fixed to the lid 120 by, for example, crimping from the outside of the lid 120, as will be described later.

[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 a through-hole 201 provided in the positive terminal 200 and is then crimped from the outside (from the upper side of the lid 120 in FIG. 2 ). As a result, the positive terminal 200, along with the upper gasket 300, the lower gasket 400, and the positive electrode current collector 600, are fixed to the lid 120. The same applies to the negative electrode side. The positive terminal 200 and the negative terminal 210 are each 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 that is connected (joined) to the tab bundle 710 of the electrode assembly 700 by welding or the like, and is disposed parallel to the XY plane. The tab bundle 710 (see FIG. 2 ) of the electrode assembly 700 is joined by welding to a first surface 603 a of the electrode connection portion (the surface opposite to the lid 120). In this way, the electrode connection portion 603 is joined to the tab bundle 710 of the electrode assembly 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] Instead of the shank 601 being integrally formed with the terminal connection portion 602, as shown in FIG. 4 , the shank 601 may be separate from the terminal connection portion 602. The shank 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.

[0040] The positive electrode current collector 600 shown in Figure 4 has low difficulty in the process of press-forming the shaft portion 601 and the terminal connection portion 602 and the process of integrating them, which allows for reduced component costs. The terminal connection portion 602 and the shaft portion 601 can be made of different materials, which increases the freedom of component selection. Furthermore, because the flange portion 601b has a predetermined area, it is easy to firmly fix the flange portion 601b to the terminal connection portion 602.

[0041] 2, 3, and 4, 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. 5, 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.

[0042] In addition, an example has been shown in which the tab bundles 710, 720 of the electrode body 700 are connected to the first surface 603a of the electrode connection portion 603, but this is not limited to this, and it is also possible to connect the tab bundles 710, 720 to the second surface 603b of the electrode connection portion 603.

[0043] 6 shows the state in which the shaft portion 601 is crimped to the positive terminal 200 from outside the lid 120. In this embodiment, the positive terminal 200 has a through-hole 201 through which the shaft portion 601 passes, as well as a countersunk portion 201a with a larger opening area than the through-hole 201. A crimped portion 601d at the tip of the shaft portion 601 rides on a seat portion 201b of the countersunk portion 201a. Between the crimped portion 601d and the terminal connection portion 602, the seat portion 201b of the positive terminal 200, the upper gasket 300, the lid 120, and the lower gasket 400 are sandwiched and a compressive force is applied to them in the Z-axis direction. The crimped portion 601d is formed by machining, such as crimping from outside the lid 120.

[0044] The step of crimping the shaft portion 601 to the positive terminal 200 may be performed after the step of joining the positive electrode tab bundle 710 shown in Fig. 2 to the electrode connection portion first surface 603a (see Fig. 3) of the positive electrode current collector 600. As shown in Fig. 3, the terminal connection portion 602, the connection portion 605, the intermediate portion 604, and the connection portion 606 are present between the shaft portion 601 and the electrode connection portion 603. Therefore, the external force acting on the shaft portion 601 when crimping the shaft portion 601 is absorbed by these portions, and the effect on the joint between the positive electrode tab bundle 710 and the electrode connection portion first surface 603a is limited.

[0045] 7 shows another example in which the shaft portion 601 is crimped to the positive terminal 200 from the outside of the lid 120. In this example, a ring member 205 is provided (sandwiched in the Z-axis direction) between the crimped portion 601d and the seat of the countersunk portion 201a. In the unlikely event that electrolyte leaks from the crimped portion 601d and comes into contact with the positive terminal 200, causing a ground fault or other problem, the ring member 205 is provided as shown in the figure to prevent leakage from the crimped portion 601d.

[0046] [3 Description of Effects] According to this embodiment, the terminal connection portion 602 and the electrode connection portion 603 are disposed 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, allowing a larger electrode body 700 to be disposed. This allows the energy density of the energy storage element 10 to be improved.

[0047] According to this embodiment, the shaft portions 601, 611 can be mechanically joined to the cell terminals 200, 210 from the outside of the lid 120 by crimping or the like, which reduces the possibility that foreign matter such as metal powder that may be generated during this process will enter the inside of the container 100. The external force acting when crimping the shaft portions 601, 610 is absorbed by the terminal connection portion 602, connection portion 605, intermediate portion 60, and connection portion 606, and the effect on the joints between the tab bundles 710, 720 and the current collectors 600, 610 is limited.

[0048] As shown in Figures 6 and 7, if a hollow rivet is used for the shaft portion 601, the external force required to crimp the shaft portion 601 is small, and the impact on the joints between the tab bundles 710, 720 and the current collectors 600, 610 can be further reduced.

[0049] The present invention is not limited to the above-described embodiment and can be modified as appropriate. Instead of the hollow rivet shown in Figures 6 and 7, a solid rivet such as that shown in Figure 3 may be used for the shank 601.

[0050] A metal or resin ring member may be used as ring member 205 shown in Fig. 7. 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. 2.

[0051] Press-fitting may be used to secure a separate shank 601, such as that shown in FIGS. 4 and 5, to the terminal connection portion 602. As shown in FIG. 8(a), the shank 601 may have a rivet portion 601a and a press-fit portion 601c formed at the lower end of the rivet portion 601a and having a smaller diameter than the rivet portion 601a. ​​The press-fit portion 601c is press-fitted from above in FIG. 8(a) into a press-fit hole formed in the terminal connection portion 602. A shoulder portion around the press-fit portion 601c contacts the upper surface of the terminal connection portion 602. A welded portion (weld mark) 601d is formed at the boundary between the press-fit portion 601c and the press-fit hole by laser welding or the like. Because the height of the press-fit portion 601c is smaller than the plate thickness of the terminal connection portion 602, the welded portion 601d is located within the press-fit hole. In the example of FIG. 8(b), the height of the press-fit portion 601c is greater than the plate thickness of the terminal connection portion 602. The press-fit portion 601c protrudes downward from the lower surface of the terminal connection portion 602. The welded portion 601d is formed at the boundary between the lower surface of the terminal connection portion 602 and the press-fit portion 601c. In the example of FIG. 8(c), the diameter of the press-fit portion is greater than the diameter of the rivet portion 601a, and the height of the press-fit portion is greater than the plate thickness of the terminal connection portion 602. The press-fit portion protrudes downward from the lower surface of the terminal connection portion 602. The welded portion 601d is formed at the boundary between the lower surface of the terminal connection portion 602 and the press-fit portion.

[0052] Other features of the embodiments are described below.

[0053] (3) In the energy storage element of (1), the shaft portion may have a rivet portion extending in the first direction and a press-fit portion formed at an end of the rivet portion and press-fitted into a press-fit hole of the terminal connection portion. According to the configuration of (3), a current collector having a shaft portion can be easily formed.

[0054] (4) In the energy storage element of (3), a welded portion may be formed at the boundary between the press-fit hole and the press-fit portion. According to the configuration of (4), the rivet portion and the terminal connection portion can be securely fixed. Therefore, machining such as crimping can be stably performed on the rivet portion.

[0055] (5) In the energy storage element of (2) or (3) above, the shanks 601, 611 protruding from the terminal connection portion 602 may be hollow rivets. According to the configuration of (5) above, after joining the tab bundles 710, 720 and the current collectors 600, 610, only a small external force is required when crimping and joining the shanks 601, 611 to the cell terminals 200, 210, and the influence on the joining points between the tab bundles 710, 720 and the current collectors 600, 610 can be reduced.

[0056] (6) In any of the energy storage elements (1) to (5) above, the cell terminals may include a positive terminal 200 and a negative terminal 210 spaced apart in the longitudinal direction of the lid 120 of the container. The current collectors may include a positive electrode current collector 600 and a negative electrode current collector 610 corresponding to the positive terminal 200 and the negative terminal 210. When viewed from the first direction (Z-axis direction), the terminal connection portion 602 (intermediate portion 604) of the positive electrode current collector 600, the electrode connection portion 603 of the positive electrode current collector 600, the electrode connection portion of the negative electrode current collector 610, and the terminal connection portion (intermediate portion) of the negative electrode current collector 610 may be arranged in this order in the longitudinal direction.

[0057] According to the above configuration (6), the terminal connection portions 602 of the positive electrode current collector 600 and the negative electrode current collector 610 are disposed near the longitudinal end (X-axis direction) of the lid body 120, and the electrode connection portions 603 of the positive electrode current collector 600 and the negative electrode current collector 610 are disposed near the longitudinal center of the lid body 120. When the shaft portions 601, 611 protruding from the terminal connection portions 602 are crimped to the cell terminals 200, 210, the terminal connection portions 602 are easily held with a jig because they are disposed near the end of the lid body 120. This facilitates joining of the shaft portions 601, 611 to the cell terminals 200, 210, improving the ease of assembly of the energy storage element.

[0058] When the terminal connection portion 602 is disposed near the center of the lid body 120 in the longitudinal direction, the positive electrode tab bundle 710 and the negative electrode tab bundle 720 are disposed on either side of the terminal connection portion 602. Therefore, in order to hold the terminal connection portion 602 in a jig, the jig must be accessed from the short side direction (Y-axis direction) of the lid body 120 (the jig must be accessed while avoiding the tab bundles 710, 720). On the other hand, when the terminal connection portion 602 is disposed near the end of the lid body 120 in the longitudinal direction, the jig can be accessed not only from the short side direction (Y-axis direction) of the lid body 120 but also from the end of the lid body 120 in the longitudinal direction (X-axis direction) in order to hold the terminal connection portion 602 in the jig. Therefore, there is a high degree of freedom in holding the terminal connection portion 602 in the jig, improving the assembly of the energy storage element.

[0059] REFERENCE SIGNS LIST 10 Energy storage element 100 Container 200 Positive terminal (cell terminal) 600 Positive electrode current collector (current collector) 601 Shaft portion 602 Terminal connection portion 603 Electrode connection portion 604 Intermediate portion 700 Electrode body

Claims

1. An energy storage element comprising: a container; a cell terminal provided outside the container; an electrode body housed in the container; and a current collector connecting the cell terminal and the electrode body, wherein the current collector has a terminal connection portion, a shaft portion protruding from the terminal connection portion in a first direction and connected to the cell terminal, and an electrode connection portion located on the opposite side of the terminal connection portion from the side where the shaft portion protrudes and connected to the electrode body in the first direction, and the electrode connection portion is connected to the terminal connection portion via a connection portion extending from the terminal connection portion to the opposite side, and partially faces the terminal connection portion when viewed in the first direction.

2. The energy storage element according to claim 1, wherein the shaft portion has a flange portion and a rivet portion that protrudes from the flange portion and passes through the terminal connection portion, and the flange portion is disposed in the gap between the terminal connection portion and the electrode connection portion.

3. The energy storage element according to claim 1, wherein the shaft portion has a rivet portion extending in the first direction and a press-fit portion formed at the end of the rivet portion and press-fitted into a press-fit hole in the terminal connection portion.

4. The energy storage element according to claim 3, wherein a weld is formed at the boundary between the press-fit hole and the press-fit portion.

5. The energy storage element according to claim 2 or 3, wherein the shank protruding from the terminal connection portion is a hollow rivet.

6. The energy storage element according to claim 1, wherein the cell terminals have a positive terminal and a negative terminal spaced apart in the longitudinal direction of the lid of the container, the current collectors have a positive electrode current collector and a negative electrode current collector corresponding to the positive terminal and the negative terminal, and when viewed from the first direction, the terminal connection portion of the positive electrode current collector, the electrode connection portion of the positive electrode current collector, the electrode connection portion of the negative electrode current collector, and the terminal connection portion of the negative electrode current collector are arranged side by side in this order in the longitudinal direction.

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