Method for manufacturing power storage element, and power storage element

Abstract

Provided is a method for manufacturing a power storage element including a current collector and an electrode body that includes a connection part connected to the current collector. The connection part includes a plurality of laminated current collector foils. The method includes: forming a foil joint part in which the plurality of current collector foils are joined in a predetermined range including an end edge of the connection part; and forming a weld part by welding the end edge included in the foil joint part and the current collector.

Description

Electricity storage element manufacturing method and electricity storage element

[0001] The present invention relates to a method for manufacturing an energy storage element and to an energy storage element.

[0002] Patent Document 1 discloses a battery including an electrode assembly, a positive electrode terminal, and a positive electrode current collector. The electrode assembly includes a positive electrode tab group formed by stacking a plurality of positive electrode tabs. The positive electrode tab group is electrically connected to the positive electrode terminal via the positive electrode current collector. The positive electrode tabs that make up the positive electrode tab group include a positive electrode tab joint joined to the positive electrode current collector.

[0003] Japanese Patent Application Laid-Open No. 2023-015681

[0004] In the battery disclosed in Patent Document 1, the positive electrode tab joint is provided in the center of the positive electrode tab group when viewed from the stacking direction of the positive electrode tabs. Therefore, when joining the positive electrode tab group to the positive electrode current collector (i.e., when forming the positive electrode tab joint), it is difficult to check the state of the portions of the multiple positive electrode tabs included in the positive electrode tab joint. This can lead to problems such as inability to form the positive electrode tab joint with precision.

[0005] The present invention was made by the inventors of the present application by focusing on the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing an electric storage element with improved reliability, and an electric storage element.

[0006] A manufacturing method for a storage element according to one embodiment of the present invention is a manufacturing method for a storage element comprising an electrode body and a current collector, wherein the electrode body comprises a connection portion connected to the current collector, and the connection portion comprises a plurality of stacked current collector foils, and the manufacturing method includes forming a foil joint portion in which the plurality of current collector foils are joined in a predetermined range including an edge of the connection portion, and forming a weld portion by welding the edge included in the foil joint portion to the current collector.

[0007] An energy storage element according to one embodiment of the present invention comprises an electrode body and a current collector, the electrode body comprising a connection portion connected to the current collector, the connection portion comprising a plurality of stacked current collector foils, a foil joint portion where the plurality of current collector foils are joined and formed in a predetermined range including the edge of the joint portion, and a weld portion formed in a range including the edge of the foil joint portion, the weld portion being a portion welded to the current collector.

[0008] According to the method for manufacturing an energy storage element according to the present invention, an energy storage element with improved reliability can be provided.

[0009] FIG. 1 is a perspective view showing the appearance of an energy storage element according to an embodiment. FIG. 2 is a perspective view showing the internal configuration of a container according to an embodiment. FIG. 3 is an exploded perspective view showing components of an energy storage element according to an embodiment, except for a container body, in an exploded view. FIG. 4 is a side view showing the configuration of a current collector joint according to an embodiment. FIG. 5 is a cross-sectional view showing the configuration of a current collector joint according to an embodiment. FIG. 6 is a flowchart showing manufacturing steps in a method for manufacturing an energy storage element according to an embodiment. FIG. 7 is a perspective view showing a step of bundling and joining multiple current collector foils provided at a connection portion of an electrode assembly in a method for manufacturing an energy storage element according to an embodiment. FIG. 8 is a perspective view showing a step of arranging an electrode assembly connection portion of a current collector in a method for manufacturing an energy storage element according to an embodiment. FIG. 9 is a perspective view showing a step of bending a connection portion and arranging the connection portion relative to the electrode assembly connection portion in a method for manufacturing an energy storage element according to an embodiment. FIG. 10 is a perspective view showing a step of forming a welded portion by laser welding in a method for manufacturing an energy storage element according to an embodiment. FIG. 11 is a first schematic view illustrating a method for forming a foil joint according to a first modified example of the embodiment. Fig. 12 is a second schematic diagram illustrating a method for forming a foil joint according to Modification 1 of the embodiment. Fig. 13A is a schematic diagram illustrating a configuration of a foil joint according to Modification 2 of the embodiment. Fig. 13B is a cross-sectional view illustrating a configuration of a foil joint according to Modification 2 of the embodiment. Fig. 14 is a plan view illustrating an example of an energy storage device according to Modification 3 of the embodiment. Fig. 15 is a schematic diagram illustrating a process for trimming and aligning edges of current collecting foils included in a connection portion.

[0010] (1) A manufacturing method for a storage element according to one aspect of the present invention is a manufacturing method for a storage element including an electrode body and a current collector, wherein the electrode body includes a connection portion connected to the current collector, and the connection portion includes a plurality of stacked current collector foils, and the manufacturing method includes forming a foil joint portion in which the plurality of current collector foils are joined in a predetermined range including an edge of the connection portion, and forming a weld portion by welding the edge included in the foil joint portion to the current collector.

[0011] According to a manufacturing method for an energy storage element of one aspect of the present invention, a foil joint portion is formed in which multiple current collecting foils are joined in a predetermined area including the edge of the connection portion of the electrode body. Furthermore, the edge of the connection portion is welded to the current collector. Therefore, when welding the connection portion to the current collector, it is easy to check the positioning of the edge relative to the current collector. This allows for a highly reliable welded portion to be obtained. Thus, according to the manufacturing method for an energy storage element of this aspect, an energy storage element with improved reliability can be obtained.

[0012] (2) In the method for manufacturing an energy storage element described in (1) above, the foil joints may be formed by ultrasonic welding, and the welds may be formed by laser welding.

[0013] According to the manufacturing method of the energy storage element described in (2) above, for example, a foil joint portion in which adjacent current collecting foils are solid-state welded to each other can be formed in a relatively short time. Furthermore, because the current collecting foils are solid-state welded to each other in the portion including the edge of the connection portion, heat from the laser light spreads efficiently. Therefore, a weld can be formed at the edge of the connection portion with high precision and / or in a relatively short time.

[0014] (3) In the manufacturing method of the energy storage element described in (2) above, forming the welded portion may involve irradiating laser light along the edge, thereby forming the welded portion extending along the edge.

[0015] According to the manufacturing method of the energy storage element described in (3) above, a welded portion is formed extending along the edge of the connection portion, thereby achieving effects such as a reduction in electrical resistance due to an increased joint area, and / or an improvement in the connection strength between the electrode body and the current collector due to the welded portion.

[0016] (4) In the manufacturing method of the energy storage element described in (2) or (3) above, the weld may be formed by irradiating the edge and the current collector with laser light.

[0017] According to the manufacturing method of the energy storage element described in (4) above, since the laser beam is irradiated onto both the edge of the connection portion and the current collector, a weld is efficiently formed in which, for example, the edge of the connection portion and the current collector are melted and solidified, thereby further improving the reliability of the weld, which is the connection portion between the connection portion and the current collector.

[0018] (5) In the method for manufacturing an energy storage element described in any one of (1) to (4) above, forming the foil joint portion may involve forming a portion where the multiple current collecting foils are joined, and then cutting the portion to form the foil joint portion in the specified range.

[0019] According to the manufacturing method of the energy storage element described in (5) above, a portion where multiple current collecting foils are joined is formed in an area that does not include the edge of the connection portion, and then the portion is cut, thereby obtaining a foil joint portion formed in a predetermined area that includes the edge of the connection portion. By cutting the portion, an edge of the connection portion that is partly included in the foil joint portion is created. This makes it possible to easily obtain a foil joint portion formed in a predetermined area that includes the edge of the connection portion.

[0020] (6) An energy storage element according to one aspect of the present invention comprises an electrode body and a current collector, the electrode body comprising a connection portion connected to the current collector, the connection portion comprising a plurality of stacked current collector foils, a foil joint portion at which the plurality of current collector foils are joined and formed in a predetermined range including an edge of the joint portion, and a weld portion formed in a range including the edge of the foil joint portion, the weld portion being a portion welded to the current collector.

[0021] In the energy storage element according to one embodiment of the present invention, a weld is formed on the edge of the connection portion of the electrode assembly. Therefore, for example, when welding the connection portion to the current collector, it is easy to check the position of the edge relative to the current collector. This allows for a highly reliable weld. In this way, the energy storage element according to this embodiment is an energy storage element with improved reliability.

[0022] Hereinafter, a method for manufacturing an energy storage element and an energy storage element according to an embodiment of the present invention (including its modified examples) will be described with reference to the drawings. The embodiments described below all show comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples and are not intended to limit the present invention. In each drawing, dimensions, etc. are not strictly illustrated. In each drawing, the same or similar components are assigned the same reference numerals.

[0023] In the following description and drawings, the X-axis direction is defined as the direction in which the short sides of the container of the energy storage element face each other, the direction in which the pair of terminals (positive and negative electrodes; the same applies hereinafter) of the energy storage element are aligned, the direction in which the pair of current collectors are aligned, the direction in which the electrode assembly connection portions of the current collectors face, the thickness direction of the electrode assembly connection portions, the winding axis direction of the electrode assembly, or the longitudinal direction of the electrode assembly. The Y-axis direction is defined as the thickness direction of the container (the direction in which the width is smallest; the same applies hereinafter), the direction in which the long sides of the container face each other, the alignment direction of the two electrode assemblies, or the thickness direction of one electrode assembly. The Z-axis direction is defined as the alignment direction of the container body and lid of the container, the alignment direction of the electrode assemblies and terminals, the direction in which the terminals protrude from the container, the direction in which the terminal connection portions of the current collectors face, the thickness direction of the terminal connection portions, or the up-down direction. The X-axis direction, Y-axis direction, and Z-axis direction intersect each other (orthogonal in this embodiment). Depending on the usage mode, the Z-axis direction may not be the up-down direction; however, for convenience of explanation, the Z-axis direction will be described below as the up-down direction.

[0024] In the following description, the positive X-axis direction refers to the direction of the X-axis arrow, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. When simply referring to the X-axis direction, it refers to both or either of the positive X-axis direction and the negative X-axis direction. The same applies to the Y-axis and Z-axis directions. Expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the directions or attitudes are not strictly the same. Two directions being parallel (or perpendicular) does not only mean that the two directions are completely parallel (or perpendicular), but also means that the two directions are substantially parallel (or perpendicular), i.e., there is a difference of a few percent. In the following description, the term "insulation" means "electrical insulation." It is preferable that the insulating material be formed from a material with a volume resistivity of 1×10 Ωm or more, more preferably 1×10 Ωm or more, and even more preferably 1×10 Ωm or more.

[0025] (Embodiment) [1. Description of the configuration of energy storage element 10] First, the configuration of energy storage element 10 according to the embodiment will be described with reference to Figs. 1 to 3. Fig. 1 is a perspective view showing the appearance of energy storage element 10 according to the embodiment. Fig. 2 is a perspective view showing the internal configuration of container 100 according to the embodiment. Fig. 3 is an exploded perspective view showing components of energy storage element 10 according to the embodiment other than container body 110.

[0026] The energy storage element 10 is a secondary battery (single cell) that can charge and discharge electricity, and more specifically, a nonaqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is used as a battery for driving or starting the engine of a mobile object such as an automobile, a motorcycle, or an electric railway vehicle. Examples of such automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs). The energy storage element 10 can also be used as a stationary battery for home or business use.

[0027] 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, or may be a capacitor. The energy storage element 10 may be a primary battery instead of a secondary battery. The energy storage element 10 may be a battery using a solid electrolyte. In the present embodiment, the energy storage element 10 is illustrated as having a rectangular parallelepiped (square) shape that is flattened in the Y-axis direction, but the shape of the energy storage element 10 is not limited to a rectangular parallelepiped shape, and may be a polygonal prism shape other than a rectangular parallelepiped, an elongated cylinder shape, an elliptical cylinder shape, a cylindrical shape, or the like.

[0028] As shown in FIG. 1 , the energy storage element 10 includes a container 100, a pair of (positive and negative) terminals 200, and a pair of (positive and negative) upper gaskets 310. As shown in FIGS. 2 and 4 , the energy storage element 10 further includes an electrode assembly 400, a pair of (positive and negative) lower gaskets 320, and a pair of (positive and negative) current collectors 500 housed within the container 100. An electrolyte (non-aqueous electrolyte) is sealed within the container 100, but is not shown. The type of electrolyte is not particularly limited as long as it does not impair the performance of the energy storage element 10, and various electrolytes can be selected. In addition to the above components, the energy storage element 10 may also include spacers disposed on the sides or below the electrode assembly 400, an insulating film encasing the electrode assembly 400, and the like.

[0029] [1-1. Description of Container 100] The container 100 is a rectangular parallelepiped (square or box-shaped) case that includes a container body 110 with an opening facing in the positive direction of the Z axis, and a lid 120 that closes the opening of the container body 110. The container body 110 is a rectangular cylindrical member with a bottom that forms the main body of the container 100. The lid 120 is a member that forms the lid of the container 100, and is disposed in the positive direction of the Z axis of the container body 110. The lid 120 is a flat, rectangular wall that extends in the X axis direction.

[0030] The container body 110 has a pair of short side walls 111 on both sides in the X-axis direction (short sides), a pair of long side walls 112 on both sides in the Y-axis direction (long sides), and a bottom wall 113 on the surface in the negative Z-axis direction (bottom surface) (see FIG. 2 ). The short side walls 111 are flat, rectangular walls extending in the Z-axis direction. The short side walls 111 are adjacent to the long side walls 112, the bottom wall 113, and the lid 120, and have a smaller area than the long side walls 112. The long side walls 112 are flat, rectangular walls extending in the X-axis direction. The long side walls 112 are adjacent to the short side walls 111, the bottom wall 113, and the lid 120, and have a larger area than the short side walls 111. The bottom wall 113 is a flat, rectangular wall extending in the X-axis direction. The bottom wall 113 is disposed adjacent to the short side wall 111 and the long side wall 112. Depending on the shape of the container 100, the short side wall 111 may be longer in the Y-axis direction, the long side wall 112 may be longer in the Z-axis direction, and the bottom wall 113 may be longer in the Y-axis direction.

[0031] After the electrode assembly 400 and other components are housed inside the container body 110, the container body 110 and the lid 120 are joined by welding or the like, thereby sealing the interior of the container 100. The material of the container 100 (the container body 110 and the lid 120) is not particularly limited, and a weldable (joinable) metal such as stainless steel, aluminum, an aluminum alloy, iron, or plated steel sheet may be used, or a resin may also be used. The container 100 may be formed of a laminate film or the like composed of multiple layers including a metal layer and a resin layer. The container body 110 and the lid 120 may be formed of the same material or different materials. The container 100 (lid 120) may be provided with a liquid injection section for injecting an electrolyte into the container 100 during the manufacture of the energy storage device 10, and a gas exhaust valve for releasing pressure inside the container 100 if the pressure inside the container 100 increases excessively.

[0032] [1-2. Description of Terminal 200, Upper Gasket 310, and Lower Gasket 320] The terminals 200 are electrode terminals (positive and negative terminals) electrically connected to the electrode assembly 400 via the current collector 500. The terminals 200 are metal members for conducting electricity stored in the electrode assembly 400 to the external space of the energy storage element 10 and for introducing electricity into the internal space of the energy storage element 10 to store electricity in the electrode assembly 400. The terminals 200 are formed of a conductive member such as a metal, such as aluminum, an aluminum alloy, copper, or a copper alloy. The terminals 200 are connected (joined) to the current collector 500 by crimping, welding, or the like, and are attached to the lid 120. The terminals 200 are arranged so as to protrude in the positive direction of the Z axis from the outer surface (the surface facing the positive direction of the Z axis) of the lid 120. In this embodiment, terminal 200 is a welding terminal that is joined to an external conductive member such as a bus bar by welding, but terminal 200 may also be a bolt terminal that has a bolt portion formed with a male thread portion that protrudes in the positive direction of the Z axis and is joined to the conductive member by a bolt connection.

[0033] In this embodiment, two terminals 200 (a positive terminal 200 and a negative terminal 200) are arranged side by side in the X-axis direction. Hereinafter, one of the two terminals 200 (the terminal 200 located in the positive direction of the X-axis) will be referred to as a first terminal 210, and the other (the terminal 200 located in the negative direction of the X-axis) will be referred to as a second terminal 220. In this embodiment, the first terminal 210 is the positive terminal 200 (positive terminal), and the second terminal 220 is the negative terminal 200 (negative terminal).

[0034] The upper gasket 310 is a plate-like, rectangular gasket that is disposed between the lid 120 of the container 100 and the terminal 200, and is responsible for insulation and sealing between the lid 120 and the terminal 200. The lower gasket 320 is a plate-like, rectangular gasket that is disposed between the lid 120 and the current collector 500, and is responsible for insulation between the lid 120 and the current collector 500. The upper gasket 310 and the lower gasket 320 can be made of any suitable known material, such as an insulating material such as resin.

[0035] [1-3. Description of the Electrode Assembly 400] The electrode assembly 400 is an electricity storage element (power generation element) formed by stacking positive and negative electrode plates and a separator, capable of storing electricity. The electrode assembly 400 is a wound-type electrode assembly formed by winding the positive and negative electrode plates and a separator around a winding axis extending in the X-axis direction. The winding axis is an imaginary axis that serves as the central axis when winding the positive and negative electrode plates, etc., and in this embodiment, is a straight line that passes through the center of the electrode assembly 400 and is parallel to the X-axis direction. In this embodiment, the electrode assembly 400 has an elongated shape extending in the X-axis direction and has a substantially oval cylindrical shape (an oval shape when viewed from the X-axis direction). The shape of the electrode assembly 400 is not particularly limited and may be a substantially cylindrical shape or a substantially elliptical cylindrical shape, and the length of the electrode assembly 400 in the X-axis direction is also not particularly limited. The electrode assembly 400 may be elongated in the Z-axis direction.

[0036] The positive electrode plate is an electrode plate in which a positive electrode active material layer is formed on the surface of a positive electrode current collector foil, which is a long, strip-shaped current collector foil (metal foil) made of a metal such as aluminum or an aluminum alloy. The negative electrode plate is an electrode plate in which a negative electrode active material layer is formed on the surface of a negative electrode current collector foil, which is a long, strip-shaped current collector foil (metal foil) made of a metal such as copper or a copper alloy. Any known material can be used for the positive electrode current collector foil and the negative electrode current collector foil, as long as it is stable against oxidation-reduction reactions during charging and discharging. Any known material can be used for the positive electrode active material used in the positive electrode active material layer and the negative electrode active material used in the negative electrode active material layer, as long as it is capable of absorbing and releasing charge-transporting ions.

[0037] The separator is a microporous insulating sheet made of resin or the like. Any known material can be used as the separator material as long as it does not impair the performance of the energy storage element 10. Examples of the separator include woven fabric, nonwoven fabric, and porous resin film.

[0038] The positive electrode plate has multiple tabs (positive electrode tabs) protruding to one side in the X-axis direction. By winding the positive electrode plate, the multiple tabs (positive electrode tabs) are stacked to form a positive electrode connection portion 420. The negative electrode plate has multiple tabs (negative electrode tabs) protruding to the other side in the X-axis direction. By winding the negative electrode plate, the multiple tabs (negative electrode tabs) are stacked to form a negative electrode connection portion 420. More specifically, the tabs of the positive electrode plate are a part of the positive electrode current collector foil on which the positive electrode active material layer is not formed. The tabs of the negative electrode plate are a part of the negative electrode current collector foil on which the negative electrode active material layer is not formed. In the following description and drawings, the tabs of the positive electrode plate and the tabs of the negative electrode plate are each referred to as a "current collector foil 405." The positive and negative electrode connection portions 420 of the electrode assembly 400 are formed by stacking current collector foils 405 (see FIG. 3 ). The connection portions 420 are also referred to as a "tab portion" or a "tab group."

[0039] Thus, the electrode body 400 comprises an electrode body main body part 410, a positive electrode connection part 420 that protrudes in the positive direction of the X-axis from the electrode body main body part 410, and a negative electrode connection part 420 that protrudes in the negative direction of the X-axis from the electrode body main body part 410. The electrode body main body part 410 is the main body part of the electrode body 400, and is an elongated cylindrical part formed by winding together the separator and the parts of the positive and negative electrode plates on which the active material layers are formed.

[0040] In this embodiment, the energy storage element 10 includes two electrode bodies 400, which are referred to as electrode body 401 and electrode body 402 when they are to be distinguished from each other. As shown in Fig. 3 , the electrode body 401 includes an electrode body main body 410, a connection part 421 which is the positive electrode connection part 420, and a connection part 423 which is the negative electrode connection part 420. The electrode body 402 includes the electrode body main body 410, a connection part 422 which is the positive electrode connection part 420, and a connection part 424 which is the negative electrode connection part 420.

[0041] The connection parts 421 and 422, which are the connection parts 420 of the positive electrode, are connected to a first current collector 510, which will be described later. The connection parts 423 and 424, which are the connection parts 420 of the negative electrode, are connected to a second current collector 520, which will be described later.

[0042] [1-4. Description of the current collectors 500] The current collectors 500 are conductive current collecting members (positive electrode current collector and negative electrode current collector) that are arranged on both sides of the electrode body 400 in the X-axis direction and are connected (joined) to the electrode body 400 and the terminal 200, electrically connecting the electrode body 400 and the terminal 200. The current collectors 500 have a shape formed by bending a single plate-like member. The current collector 500 is an L-shaped member when viewed from the Y-axis direction. The current collector 500 has a simple configuration and is therefore easy to manufacture. Because the current collector 500 can be formed from a single plate-like member, there is no need to provide a separate lead, etc., and the number of parts can be reduced. Furthermore, by reducing the space occupied by the current collectors 500 (space saving), the capacity of the energy storage element 10 can be improved.

[0043] More specifically, the current collector 500 includes a terminal connection portion 511 that is connected to the terminal 200, and an electrode assembly connection portion 512 that is connected to the electrode assembly 400. The terminal connection portion 511 and the electrode assembly connection portion 512 are both flat plate-shaped, and are connected to form an L-shape as described above.

[0044] The terminal connection portion 511 is a flat, rectangular portion parallel to the XY plane. The terminal connection portion 511 is connected to the terminal 200 by, for example, crimping. The terminal connection portion 511 is arranged in the negative Z-axis direction of the lid 120 and has a through-hole 501 through which the shank 201 (see FIG. 3 ) of the terminal 200 passes. The shank 201 is a rivet portion extending in the negative Z-axis direction from the terminal body of the terminal 200. The shank 201 is inserted into the through-hole 311 of the upper gasket 310, the through-hole 121 of the lid 120, the through-hole 321 of the lower gasket 320, and the through-hole 501 of the terminal connection portion 511, and crimped. As a result, the current collector 500 is fixed to the lid 120 together with the terminal 200. The method for connecting the current collector 500 and the terminal 200 is not limited to crimping, and welding such as ultrasonic welding, laser welding, or resistance welding, or mechanical joining other than crimping such as screw joining, may also be used.

[0045] In this embodiment, two current collectors 500 are arranged side by side in the X-axis direction. Hereinafter, when distinguishing between these two current collectors 500, the current collector 500 located in the positive direction of the X-axis will be referred to as the first current collector 510, and the current collector 500 located in the negative direction of the X-axis will be referred to as the second current collector 520. In this embodiment, the first current collector 510 is the positive electrode current collector 500, and the second current collector 520 is the negative electrode current collector 500. As shown in FIG. 3 , the first current collector 510 is connected to the first terminal 210, and the second current collector 520 is connected to the second terminal 220. The first current collector 510 (positive electrode current collector) is formed of aluminum, an aluminum alloy, or the like, similar to the positive electrode current collector foil of the electrode assembly 400. The second current collector 520 (negative electrode current collector) is formed of copper, a copper alloy, or the like, similar to the negative electrode current collector foil of the electrode assembly 400.

[0046] The connection portions 420 of the electrode assemblies 400 are connected to the electrode assembly connection portions 512 of these two current collectors 500. As shown in Figures 2 and 3, the electrode assembly connection portion 512 of the current collector 500 is a flat, rectangular portion parallel to the YZ plane. More specifically, the two positive electrode connection portions 420 (connections 421 and 422) of the two electrode assemblies 400 are connected to the electrode assembly connection portion 512 of the first current collector 510. The two negative electrode connection portions 420 (connections 423 and 424) of the two electrode assemblies 400 are connected to the electrode assembly connection portion 512 of the second current collector 520.

[0047] More specifically, the connection portion 420 of the electrode assembly 400 is connected (joined) to the electrode assembly connection portion 512 of the current collector 500 through at least two steps. As a result, a current collector joint portion 600 (see FIG. 2 ) including a portion welded to the electrode assembly connection portion 512 is formed in the connection portion 420.

[0048] [1-5. Description of Current Collector Joint 600] Next, the configuration of the current collector joint 600 formed in the connection portion 420 of the electrode assembly 400 according to this embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a side view showing the configuration of the current collector joint 600 according to this embodiment. FIG. 4 is a view of the configuration shown in FIG. 2 (excluding the container body 110) as viewed from the positive direction of the X axis, and the upper gasket 310 and the lower gasket 320 are omitted from the illustration. FIG. 5 is a cross-sectional view showing the configuration of the current collector joint 600 according to this embodiment. FIG. 5 shows a cross section of the configuration shown in FIG. 4 taken along a plane parallel to the XY plane including the V-V line.

[0049] 2 and 4, the current collector joint 600 includes a portion that joins the electrode assembly connection portion 512 and the connection portion 420. In the present embodiment, the current collector joint 600 is formed in an elongated shape along the direction in which the electrode assembly connection portion 512 extends (the Z-axis direction in the present embodiment). The current collector joint 600 is formed in each of the connection portions 421 and 422. As shown in FIGS. 4 and 5, the current collector joint 600 includes a foil joint 610 and a welded portion 620.

[0050] The foil joint 610 is formed by joining multiple current collecting foils 405 (see FIGS. 3 and 5 ) included in the connection portion 420 of the electrode assembly 400. More specifically, the foil joint 610 is a continuous portion in the stacking direction where two adjacent current collecting foils 405 of the multiple stacked current collecting foils 405 are joined. The foil joint 610 is formed in a predetermined range including the edge 420 a of the connection portion 420. In the present embodiment, the foil joint 610 is formed by ultrasonic welding. In the foil joint 610, the two adjacent current collecting foils 405 are solid-state joined. The joining method for forming the foil joint 610 may be a method other than ultrasonic welding, such as resistance welding, laser welding, crimping, or screw joining. However, ultrasonic welding is preferred from the viewpoints of increasing the area of ​​the foil joint 610 when viewed in the stacking direction of the multiple current collecting foils 405 and / or relatively easily forming the foil joint 610.

[0051] Welded portion 620 is a portion of connecting portion 420 that is welded to current collector 500 (more specifically, electrode assembly connecting portion 512). In the present embodiment, welded portion 620 is formed in a range that includes edge 420a of foil joining portion 610. In the present embodiment, welded portion 620 is provided to extend in the Z-axis direction along edge 420a that extends in the Z-axis direction.

[0052] In this embodiment, the weld 620 is formed by laser welding using a laser beam. The weld 620 can also be described as a laser weld mark formed by laser welding the foil joint 610 and the electrode assembly connection portion 512 together. More specifically, the weld 620 is a portion where the portion of the foil joint 610 including the edge 420a and the electrode assembly connection portion 512 are melted and solidified together. Therefore, in a cross section of the current collector joint 600 perpendicular to the direction in which the edge 420a extends (the Z-axis direction), the foil joint 610 and the weld 620 are aligned in the Y-axis direction, as shown in FIG. 5 . Furthermore, in this embodiment, the edge 420a of the connection portion 420 is an edge located at the tip of the connection portion 420 in the direction of protrusion from the electrode body main body 410. Therefore, as shown in Figure 4, the welded portion 620 formed on the connection portion 420 of the electrode body 401 and the welded portion 620 formed on the connection portion 420 of the electrode body 402 are arranged opposite each other in the alignment direction of the electrode bodies 401 and 402 (Y-axis direction).

[0053] Thus, in the energy storage element 10 according to this embodiment, the connection portion 420 of the electrode body 400 includes a current collector joint portion 600 , and the current collector joint portion 600 includes a foil joint portion 610 and a weld portion 620 .

[0054] In this embodiment, a current collector joint 600 may also be formed at the negative electrode connection 420 (connection 423 and 424 shown in FIG. 3 ) of the electrode assemblies 401 and 402. The current collector joint 600 formed at the connection 423 and 424 has the same configuration as the current collector joint 600 formed at the connection 421 and 422 (see FIG. 4 ), and therefore a description thereof will be omitted.

[0055] 6 to 10 , a method for manufacturing an energy storage element 10 according to an embodiment will be described. FIG. 6 is a flowchart showing manufacturing steps in the method for manufacturing an energy storage element 10 according to an embodiment. FIG. 7 is a perspective view showing a step of bundling and joining a plurality of current collector foils 405 provided on the connection portion 420 of the electrode assembly 400 in the method for manufacturing an energy storage element 10 according to an embodiment. FIG. 8 is a perspective view showing a step of arranging an electrode assembly connection portion 512 of a current collector 500 in the method for manufacturing an energy storage element 10 according to an embodiment. FIG. 9 is a perspective view showing a step of bending the connection portion 420 and arranging the connection portion 420 relative to the electrode assembly connection portion 512 in the method for manufacturing an energy storage element 10 according to an embodiment. FIG. 10 is a perspective view showing a step of forming a welded portion 620 by laser welding in the method for manufacturing an energy storage element 10 according to an embodiment.

[0056] The manufacturing method of the energy storage element 10 according to this embodiment includes forming a foil joint 610 in which a plurality of current collector foils 405 are joined in a predetermined range including the edge 420a of the connection portion 420 of the electrode body 400 (step S101), as shown in FIG. 6, and forming a welded portion 620 by welding the edge 420a included in the foil joint 610 to the current collector 500 (step S102).

[0057] According to this manufacturing method, a foil joint 610 is formed in which a plurality of current collecting foils 405 are joined in a predetermined range including the edge 420a of the connection portion 420 of the electrode body 400. Furthermore, the edge 420a included in the foil joint 610 is welded to the current collector 500. The portion of the foil joint 610 including the edge 420a is welded to the current collector 500. Therefore, when welding the connection portion 420 to the current collector 500, it is easy to check the positioning state of the edge 420a relative to the current collector 500. This makes it possible to obtain a highly reliable welded portion 620.

[0058] More specifically, in forming foil joint portion 610 (step S101), two adjacent current collecting foils 405 in the stacking direction are joined together among the multiple current collecting foils 405 included in connection portion 420. In foil joint portion 610, the joined portion of two adjacent current collecting foils 405 in the stacking direction is continuous in the stacking direction (see FIG. 5 ). In other words, in foil joint portion 610, there is essentially no gap between two adjacent current collecting foils 405 in the stacking direction.

[0059] In this embodiment, as shown in Fig. 7 , a foil joint portion 610 is formed in each of the connection portion 421 of the electrode body 401 and the connection portion 422 of the electrode body 402. The foil joint portion 610 of the connection portion 421 and the foil joint portion 610 of the connection portion 422 may be formed in a state in which the electrode body 401 and the electrode body 402 are overlapped in the Y-axis direction, as shown in Fig. 9 , or may be formed separately and then the electrode body 401 and the electrode body 402 are overlapped in the Y-axis direction.

[0060] In the present embodiment, when forming the weld 620 (step S102), the edge 420a included in the foil joint portion 610 is welded to the current collector 500. Therefore, compared to when a weld is formed in a region inside the edge 420a of the connection portion 420, it is easier to check the position of the edge 420a, which is the location to be welded, when forming the weld 620 (step S102). Specifically, it is easier to check the state of the gap between the edge 420a and the current collector 500. Checking the position of the edge 420a means checking whether the edge 420a is in appropriate contact with the electrode assembly connection portion 512 of the current collector 500 and / or whether the position at which the edge 420a contacts the electrode assembly connection portion 512 is appropriate.

[0061] In this way, since the positioning state of the edge 420 a can be easily confirmed, poor welding due to improper positioning of the edge 420 a during welding is less likely to occur, resulting in a highly reliable welded portion 620. The positioning state of the edge 420 a may be confirmed, for example, by a computer analyzing an image captured by an imaging device, by laser step measurement, or by visual inspection by an operator.

[0062] Furthermore, when the welded portion 620 is formed (step S102), the foil joint portion 610 has already been formed (step S101), and as a result, as described above, the joint portion of two adjacent current collecting foils 405 in the stacking direction is continuous in the stacking direction. Therefore, the welded portion 620 can be easily formed.

[0063] Furthermore, because the weld 620 is formed at the edge 420a of the foil joint 610, the impact of expansion and contraction of the foil joint 610 when it melts and solidifies due to welding on the connection portion 420 is suppressed. Specifically, if the weld is formed inside the edge 420a of the foil joint 610, a portion of the connection portion 420 that is not welded (a non-welded portion) exists around the entire area surrounding the weld. Therefore, the shrinkage caused by melting and solidifying the foil joint 610 when the weld is formed affects the entire area surrounding the weld. As a result, problems such as cracking or damage to the current collecting foil 405 included in the connection portion 420 due to the shrinkage are likely to occur. In this regard, in the present embodiment, because the weld 620 is formed at the edge 420a of the foil joint 610, the impact of shrinkage when the foil joint 610 melts and solidifies due to welding is limited (only inside the edge 420a). As a result, problems such as cracks and damage to the current collecting foil 405 are suppressed.

[0064] In this embodiment, the foil joint 610 is formed by ultrasonic welding, and the weld 620 is formed by laser welding. Therefore, two current collector foils 405 adjacent in the stacking direction are solid-state welded at the foil joint 610. This allows the heat from the laser light used to form the weld 620 (step S102) to spread efficiently in the foil joint 610. As a result, the weld 620 can be formed accurately and / or in a relatively short time at the edge 420a of the connection portion 420. The foil joint 610 is welded to the electrode body connection portion 512 efficiently and / or more reliably.

[0065] More specifically, after forming the foil joint portion 610 (step S101), as shown in Fig. 8, the electrode body connection portion 512 of the current collector 500 is positioned so as to face the electrode body main body portion 410 of the electrode body 400. Thereafter, the weld portion 620 is formed (step S102).

[0066] In forming the weld 620 (step S102), as shown in Fig. 9, laser light L is irradiated along the edge 420a of the foil joint 610, thereby forming the weld 620 extending along the edge 420a (see Figs. 4 and 10). This increases the bonding area between the connection portion 420 and the current collector 500 (more specifically, the electrode assembly connection portion 512). As a result, effects such as a reduction in electrical resistance and / or an improvement in the connection strength between the electrode assembly 400 and the current collector 500 due to the weld 620 can be obtained.

[0067] In this embodiment, as shown in FIGS. 4 and 10, a welded portion 620 is formed at each of the connection portion 421 of the electrode body 401 and the connection portion 422 of the electrode body 402.

[0068] More specifically, in forming the weld 620 (step S102), the edge 420a and the current collector 500 are irradiated with laser light L to form the weld 620. The edge 420a and the portion of the electrode assembly connection portion 512 along the edge 420a are included in the irradiation range A of the laser light L. Therefore, not only the edge 420a of the foil joint portion 610 but also the portion of the electrode assembly connection portion 512 along the edge 420a are directly heated by the laser light. As a result, the edge 420a of the connection portion 420 and the current collector 500 are melted and solidified to form the weld 620 efficiently. Therefore, a highly reliable weld 620 is obtained. In FIG. 9, the irradiation range A is schematically represented by the area surrounded by a dotted oval. The laser light L may be irradiated onto the edge 420a and the current collector 500 by moving the irradiation spot of the laser light L along the edge 420a in the Z-axis direction while reciprocating in the Y-axis direction.

[0069] The configuration of the energy storage element 10 manufactured by the above-described method for manufacturing the energy storage element 10 is described, for example, as follows. The energy storage element 10 according to this embodiment includes an electrode body 400 and a current collector 500. The electrode body 400 includes a connection portion 420 connected to the current collector 500. The connection portion 420 includes a plurality of stacked current collecting foils 405, a foil joint portion 610 to which the plurality of current collecting foils 405 are joined, and a weld portion 620 formed in a range including an edge 420a of the foil joint portion 610. The foil joint portion 610 is formed in a predetermined range including the edge 420a of the connection portion 420. The weld portion 620 is a portion welded to the current collector 500.

[0070] As described above, in the energy storage element 10 according to this embodiment, the welded portion 620 is formed on the edge 420a of the connection portion 420 of the electrode assembly 400. Therefore, compared to when the welded portion 620 is formed in an area of ​​the connection portion 420 that is more inward than the edge 420a, it is easier to check the positioning state of the edge 420a relative to the current collector 500 when welding the connection portion 420 to the current collector 500. This makes it possible to obtain a highly reliable welded portion 620. As such, the energy storage element 10 according to this embodiment is an energy storage element 10 with improved reliability.

[0071] The above has described the energy storage element 10 according to the embodiment, focusing on the configuration of the current collector joint 600 included in the energy storage element 10. However, the configuration of the current collector joint 600 included in the energy storage element 10 may be different from the configurations shown in Figures 2 to 10, and the energy storage element 10 may be used as an energy storage element included in an energy storage device. Therefore, below, modified examples of the energy storage element 10 will be described, focusing on the differences from the above embodiment.

[0072] [3-1. Modification 1] FIG. 11 is a first schematic diagram illustrating a method for forming a foil bonding portion 610 according to Modification 1 of the embodiment, and FIG. 12 is a second schematic diagram illustrating the formation method.

[0073] As described above, the connection portion 420 of the electrode body 400 has a foil joint portion 610 formed in a predetermined range including the edge 420a. When forming the foil joint portion 610 by ultrasonic bonding, the predetermined range including the edge 420a of the connection portion 420 is clamped between an ultrasonic horn and anvil and ultrasonic vibrations are applied. This forms the foil joint portion 610 including the edge 420a. However, the foil joint portion 610 including the edge 420a may also be formed after a plurality of current collecting foils 405 have been joined by a predetermined joining method such as ultrasonic bonding.

[0074] 11 , when viewed from the stacking direction of the current collecting foils 405, a foil joint 615 not including the edge 420b is formed in a portion of the connection portion 420 of the electrode body 400 that is more inward than the edge 420b. Furthermore, the connection portion 420 is cut along a cutting line C that passes through the foil joint 615. As a result, as shown in FIG. 12 , a foil joint 610 is formed in which a plurality of current collecting foils 405 are joined in a predetermined range that includes the edge 420a of the connection portion 420.

[0075] In this way, in forming the foil joint portion 610 (step S101), after forming a portion where multiple current collecting foils 405 are joined, the portion may be cut to form the foil joint portion 610 in a predetermined range including the edge 420a.

[0076] This makes it possible to easily obtain the foil joint portion 610 formed in a predetermined range including the edge 420a of the connection portion 420. More specifically, the edge 420a is formed by cutting the portion where the multiple current collector foils 405 are joined (the foil joint portion 615 in FIG. 10 ). This makes it possible to more reliably ensure that the foil joint portion 610 has the edge 420a, which is the portion to be welded to the electrode body connection portion 512.

[0077] [3-2. Modification 2] Fig. 13A is a schematic diagram showing the configuration of a foil joint 610a according to Modification 2 of the embodiment. Fig. 13A illustrates the foil joint 610a in a state before it is joined to the electrode assembly connection portion 512 of the current collector 500. Fig. 13B is a cross-sectional view showing the configuration of the foil joint 610a according to Modification 2 of the embodiment. Fig. 13B illustrates the foil joint 610a in a state joined to the electrode assembly connection portion 512 of the current collector 500. The position of the cross section in Fig. 13B corresponds to the position of the cross section in Fig. 5.

[0078] As shown in FIGS. 13A and 13B , in this modification, the foil joint 610a formed in the connection portion 420 of the electrode assembly 400 includes a melted portion of the clamping member 700, which is a conductive member (also called a backing plate). In this modification, the clamping member 700 is formed in a clip shape. In this modification, the foil joint 610a is formed by clamping and holding multiple current collecting foils 405 from both sides with the clamping member 700, and then joining the multiple current collecting foils 405 to the clamping member 700 by resistance welding, laser welding, or the like. This forms the foil joint 610a, including at least a portion of the clamping member 700, in a predetermined range including the edge 420a of the connection portion 420. The connection portion 420 with the foil joint 610a formed therein is welded to the electrode assembly connection portion 512 by, for example, laser welding. This forms the weld 620, as shown in FIG. 13B .

[0079] In this manner, in this modified example, the foil joint portion 610a is formed in a state where the multiple current collecting foils 405 provided in the connection portion 420 are bundled together by the clamping member 700, making it easier to join these multiple current collecting foils 405.

[0080] [3-3. Modification 3] The energy storage element 10 according to the present embodiment may be used in an energy storage device. In this case, the technology of the present invention may be applied to at least one energy storage element 10 included in the energy storage device. FIG. 14 is a plan view showing an example of an energy storage device 900 according to Modification 3 of the embodiment. As shown in FIG. 14 , a plurality of energy storage units 800 are arranged inside the energy storage device 900. The energy storage unit 800 is composed of a plurality of electrically connected energy storage elements 10. The energy storage device 900 may include a bus bar (not shown) that electrically connects the plurality of energy storage elements 10, a bus bar (not shown) that electrically connects the plurality of energy storage units 800, and the like. The energy storage unit 800 or the energy storage device 900 may include a state monitoring device (not shown) that monitors the state of one or more energy storage elements 10. The energy storage device 900 may include only one energy storage unit 800. The energy storage unit 800 may also be referred to as an energy storage device.

[0081] [4. Description of Other Modifications] While the energy storage device 10 according to the embodiment of the present invention and its modifications have been described above, the present invention is not limited to the above-described embodiment and modifications. The embodiments disclosed herein are illustrative in all respects, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

[0082] 4 and 10 , the length of the weld 620 and the length of the foil joint 610 are the same in the direction along the edge 420 a of the connection portion 420 (the Z-axis direction in the above embodiment). However, the length of the weld 620 and the length of the foil joint 610 in the direction along the edge 420 a do not need to be the same. Specifically, the weld 620 is formed by welding the edge 420 a included in the foil joint 610 to the current collector 500. Therefore, the length of the weld 620 may be shorter than the length of the foil joint 610 in the direction along the edge 420 a. A portion of the foil joint 610 that is not welded to the current collector 500 (a non-welded portion) may be disposed at one or both ends of the weld 620 in the direction along the edge 420 a.

[0083] In one connection portion 420 provided in the electrode assembly 400, two or more current collector joint portions 600 may be formed in a direction along the edge 420a of the connection portion 420. For example, when the width of the connection portion 420 (the length in the Z-axis direction in FIG. 7 ) is relatively long, forming a plurality of current collector joint portions 600 aligned in the Z-axis direction improves the reliability of the mechanical and / or electrical connection between the connection portion 420 and the current collector 500.

[0084] The welding method used to form the welded portion 620 is not limited to laser welding. The welded portion 620 may be formed by other welding methods such as resistance welding. However, from the viewpoint that the welded portion 620 can be formed by processing the connection portion 420 of the electrode body 400 from only one side (i.e., by irradiating laser light), it is preferable to form the welded portion 620 by laser welding.

[0085] The weld 620 does not necessarily have to extend along the edge 420a. A plurality of welds 620, each of which is a point, may be arranged along the edge 420a. The shape of the weld 620 when viewed from the positive direction of the X-axis in FIG. 4 does not have to be a long line in the Z-axis direction or a rectangle. However, from the viewpoint of improving the connection strength between the connection 420 and the current collector 500 or suppressing the electrical resistance between the connection 420 and the current collector 500, it is preferable that the weld 620 extend along the edge 420a.

[0086] In forming the welded portion 620 (S102), it is not essential that the laser beam be irradiated onto the edge 420a and the current collector 500. The welded portion 620 may be formed by irradiating the laser beam only onto the edge 420a and its vicinity in the foil joint portion 610. However, from the viewpoint of efficiently forming the welded portion 620 or further increasing the reliability of the welded portion 620, it is preferable that the welded portion 620 be formed by irradiating the edge 420a and the current collector 500 with the laser beam.

[0087] The welding method used to form the welded portion 620 is not limited to laser welding. The welded portion 620 may be formed by other welding methods, such as resistance welding. However, the space between the electrode body connection portion 512 of the current collector 500 and the electrode body main body portion 410 of the electrode body 400 is relatively narrow. Therefore, it is preferable to form the welded portion 620 by laser welding, since the welded portion 620 can be formed by processing the connection portion 420 of the electrode body 400 from only one side (i.e., by irradiating it with laser light).

[0088] Edge 420a included in foil joint portion 610 does not have to be an edge in the direction in which connection portion 420 extends (the positive direction of the X-axis in FIG. 7 ). Edge 420a included in foil joint portion 610 may be an edge in the positive direction of the Z-axis or the negative direction of the Z-axis in FIG. 7 . Even in this case, the effect of making it easy to check the positioning state of edge 420a relative to current collector 500 when welding connection portion 420 to current collector 500 can be achieved.

[0089] 15 , before performing a joining operation (ultrasonic joining or the like) to form foil joint portion 610 in connection portion 420, the edges of the multiple current collector foils 405 included in connection portion 420 in the protruding direction (the positive direction of the X-axis in FIG. 15 ; the same applies below) may be trimmed to align at cutting plane C. FIG. 15 is a schematic diagram for explaining the process of trimming the edges of current collector foils 405 included in connection portion 420.

[0090] As shown in FIG. 15 , a jig 750 is used to hold down an intermediate portion of the connection portion 420, which is a portion between the electrode body main body 410 and the end of the connection portion 420 in the protruding direction (positive direction of the X-axis). Specifically, the jig 750 clamps the intermediate portion of the connection portion 420 in the stacking direction of the current collector foils 405 (the Y-axis direction in FIG. 15 ). In this state, the connection positions of the multiple current collector foils 405 included in the connection portion 420 with the electrode body main body 410 differ from one another in the Y-axis direction, so the protruding edge portions of these multiple current collector foils 405 tend to become uneven, as shown in FIG. 15 . In this state, the protruding tip portions of one or more of the multiple current collector foils 405 may be cut off, for example, along cut plane C indicated by the two-dot chain line in FIG. 15 . This aligns the positions of the protruding edge portions of the multiple current collector foils 405 (positions in the X-axis direction). As a result, when forming the foil joint 610 (see FIGS. 7 and 8) by ultrasonic bonding or the like, the multiple current collecting foils 405 can be joined with greater precision.

[0091] After the foil joint 610 is formed but before the welded portion 620 is formed, the tip of the foil joint 610 in the protruding direction may be cut off at a cutting plane C perpendicular to the protruding direction of the connecting portion 420. This makes it possible to easily obtain the foil joint 610 formed in a predetermined range including the edge 420a of the connecting portion 420, as in the forming method according to the first modified example (see FIGS. 11 and 12 ).

[0092] The electrode body 400 may include two or more positive electrode connection parts 420, and may include two or more negative electrode connection parts 420. For example, when the electrode body 400 includes two or more positive electrode connection parts 420, it is sufficient that the foil joint part 610 shown in FIG. 4 and the like is formed on at least one of these two connection parts 420.

[0093] The number of electrode bodies 400 included in the energy storage element 10 is not limited to two. The energy storage element 10 may include only one electrode body 400. The energy storage element 10 may include three or more electrode bodies 400 arranged in the Y-axis direction. When the energy storage element 10 includes three or more electrode bodies 400, one or two of the three or more electrode bodies 400 may be connected to the current collector 500 in the manner shown in Figures 3, 4, and 7 to 10.

[0094] The shape of the current collector 500 does not have to be the shape shown in Fig. 3. The current collector 500 may have two plate-like portions corresponding to the two electrode bodies 400, the two plate-like portions being spaced apart in the Y-axis direction, as electrode body connecting portions connected to the two electrode bodies 400. The electrode body connecting portion 512 of the current collector 500 may be oriented such that its thickness direction faces the Y-axis direction. In this case, the connecting portion 420 of the electrode body 400 may be connected to the electrode body connecting portion 512 in a state extending in the X-axis direction (see Fig. 7).

[0095] The connection portion 420 of the electrode body 400 does not have to be a portion that protrudes from only a portion in the Z-axis direction at the end portion in the X-axis direction of the electrode body main body portion 410. The entire area in the Z-axis direction at the end portion in the X-axis direction of the electrode body 400 may be treated as the connection portion 420 where the current collector joint portion 600 is formed. In this case, from the viewpoint of ease of forming the current collector joint portion 600 (particularly the welded portion 620), it is preferable that the electrode body connection portion 512 is oriented so that its thickness direction is oriented in the Y-axis direction.

[0096] The electrode body 400 is not limited to a wound type electrode body, and may be a laminated (stacked) type electrode body formed by stacking a plurality of flat electrode plates, a bellows type electrode body in which electrode plates are folded in a bellows shape, or an electrode body of another form.

[0097] Any combination of the components included in the above-described embodiments and their modifications is also included within the scope of the present invention.

[0098] The present invention can be applied to an electric storage device such as a lithium ion secondary battery.

[0099] REFERENCE SIGNS LIST 10 Energy storage element 100 Container 110 Container body 111 Short side wall portion 112 Long side wall portion 113 Bottom wall portion 120 Lid body 121, 311, 321, 501 Through hole 200 Terminal 201 Shaft portion 210 First terminal 220 Second terminal 310 Upper gasket 320 Lower gasket 400, 401, 402 Electrode body 405 Current collecting foil 410 Electrode body body portion 420, 421, 422, 423, 424 Connection portion 420a, 420b Edge 500 Current collector 510 First current collector 511 Terminal connection portion 512 Electrode body connection portion 520 Second current collector 600 Current collector joint portion 610, 615 Foil joint 620 Welded part 800 Electricity storage unit 900 Electricity storage device

Claims

1. A method for manufacturing an energy storage element comprising an electrode body and a current collector, wherein the electrode body comprises a connection portion connected to the current collector, and the connection portion comprises a plurality of stacked current collector foils, the method comprising: forming a foil joint portion in which the plurality of current collector foils are joined in a predetermined area including an edge of the connection portion; and forming a weld portion by welding the edge included in the foil joint portion to the current collector.

2. The method for manufacturing an energy storage element according to claim 1, wherein the foil joint is formed by ultrasonic welding, and the welded portion is formed by laser welding.

3. The method for manufacturing an energy storage element according to claim 2, wherein forming the welded portion comprises irradiating a laser beam along the edge to form the welded portion extending along the edge.

4. The method for manufacturing an energy storage element according to claim 2 or 3, wherein forming the welded portion comprises irradiating the edge and the current collector with laser light to form the welded portion.

5. A method for manufacturing an energy storage element according to any one of claims 1 to 3, wherein forming the foil joint portion comprises forming a portion where the plurality of current collecting foils are joined, and then cutting that portion to form the foil joint portion in the predetermined range.

6. An energy storage element comprising: an electrode body; and a current collector, wherein the electrode body comprises a connection portion connected to the current collector, and the connection portion comprises: a plurality of stacked current collector foils; a foil joint portion where the plurality of current collector foils are joined, formed in a predetermined range including an edge of the joint portion; and a weld portion formed in a range including the edge of the foil joint portion, which is a portion welded to the current collector.

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