Energy storage element

Abstract

To provide a power storage element capable of improving a volume occupancy rate of an electrode body.SOLUTION: The present invention relates to a power storage element 10 in which a collector 500 includes a first collector 510 and a second collector 520 which are aligned in a first direction and joined with each other. The first collector 510 includes: a first main body part 511 joined to one of an electrode body 600 and an electrode terminal 200; and a first joint part 512 joined to the second collector 520. The second collector 520 has: a second main body part 521 joined to the other of the electrode body 600 and the electrode terminal 200; and a second joint part 522 overlapped and joined to the first joint part 512 at one side in a second direction. The first main body part 511 includes a first principal surface 511a at one side in the second direction and includes a second principal surface 511b at the other side in the second direction. In the first joint part 512, a first joint surface 512a at one side in the second direction is disposed closer to the other side in the second direction than the first principal surface 511a and disposed closer to the one side in the second direction than the second principal surface 511b.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a storage element including an electrode body, an electrode terminal, and a current collector.

Background Art

[0002] Conventionally, in a storage element including an electrode body, an electrode terminal, and a current collector joined to the electrode body and the electrode terminal, the current collector may be composed of two members. For example, in Patent Document 1, a negative electrode terminal (electrode terminal) is connected to a first negative electrode current collector, a negative electrode tab (electrode body) is connected to a second negative electrode current collector, and the second negative electrode current collector is disposed on the first negative electrode current collector and welded to the first negative electrode current collector, and a secondary battery (storage element) is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above conventional storage element, since the second negative electrode current collector is disposed on the first negative electrode current collector and welded to the first negative electrode current collector in a stacked state, the thickness of the stacked portion in the current collector is increased. Therefore, in the above conventional storage element, the space where the electrode body can be disposed is limited due to the increased thickness of the current collector, and there is a risk that the volume occupancy rate of the electrode body decreases.

[0005] The present invention has been made by the inventors of the present application newly paying attention to the above problems, and an object thereof is to provide a storage element capable of improving the volume occupancy rate of the electrode body.

Means for Solving the Problems

[0006] An energy storage element according to one aspect of the present invention comprises an electrode body, electrode terminals, and a current collector joined to the electrode body and the electrode terminals, wherein the current collector has a first current collector and a second current collector arranged side by side in a first direction and joined to each other, the first current collector is joined to one of the electrode body and the electrode terminals but not to the other, the second current collector is joined to the other but not to the one, and the first current collector has a first main body joined to the one and a first terminal joined to the second current collector The second current collector has a joint and a second main body that is joined to the other, and a second joint that is superimposed on one side of the first joint in a second direction intersecting the first direction and joined to the first joint, the first main body has a first main surface on one side in the second direction and a second main surface on the other side in the second direction, and the surface of the first joint on one side in the second direction is positioned on the other side of the second direction than the first main surface and on one side of the second direction than the second main surface in the second direction.

[0007] This invention can be realized not only as such an energy storage element, but also as a current collector. [Effects of the Invention]

[0008] The energy storage element of the present invention makes it possible to improve the volume occupancy rate of the electrode body. [Brief explanation of the drawing]

[0009] [Figure 1] This is a perspective view showing the external appearance of the energy storage element according to the embodiment. [Figure 2] This is an exploded perspective view showing the individual components of the energy storage element according to the embodiment, after disassembly. [Figure 3] This is a perspective view showing the configuration of the electrode body according to the embodiment. [Figure 4] This is a perspective view showing the configuration of the current collectors (first current collector and second current collector) according to the embodiment. [Figure 5]This is a cross-sectional view showing the current collectors (first current collector and second current collector) according to the embodiment in a state where they are joined to the electrode terminals and electrode body. [Figure 6] This is a cross-sectional view showing a current collector according to a modified example 1 of the embodiment, in a state where it is joined to the electrode terminals and electrode body. [Figure 7A] This is a cross-sectional view showing a current collector according to a modified example 2 of the embodiment, in a state where it is joined to the electrode terminals and electrode body. [Figure 7B] This is a cross-sectional view showing a current collector according to modified embodiment 3, in a state where it is joined to the electrode terminals and electrode body. [Figure 7C] This is a cross-sectional view showing a current collector according to modified embodiment 4, in a state where it is joined to the electrode terminals and electrode body. [Modes for carrying out the invention]

[0010] An energy storage element according to one aspect of the present invention comprises an electrode body, electrode terminals, and a current collector joined to the electrode body and the electrode terminals, wherein the current collector has a first current collector and a second current collector arranged side by side in a first direction and joined to each other, the first current collector is joined to one of the electrode body and the electrode terminals but not to the other, the second current collector is joined to the other but not to the one, and the first current collector has a first main body joined to the one and a first terminal joined to the second current collector The second current collector has a joint and a second main body that is joined to the other, and a second joint that is superimposed on one side of the first joint in a second direction intersecting the first direction and joined to the first joint, the first main body has a first main surface on one side in the second direction and a second main surface on the other side in the second direction, and the surface of the first joint on one side in the second direction is positioned on the other side of the second direction than the first main surface and on one side of the second direction than the second main surface in the second direction.

[0011] According to this, in the energy storage element, the current collector has a first current collector joined to one electrode body and electrode terminal and a second current collector joined to the other, and the second joint of the second current collector is joined to one side of the first joint of the first current collector in the second direction. The surface of the first joint on one side in the second direction is positioned on the other side in the second direction of the first main surface of the first main body of the first current collector on one side in the second direction, and also on one side in the second direction of the second main surface of the first main body on the other side in the second direction of the first main body. In this way, in the first current collector, the surface of the first joint on one side in the second direction is positioned on the other side in the second direction of the first main surface of the first main body, and also on one side in the second direction of the second main surface. When the surface of the first joint on one side in the second direction is positioned on one side in the second direction of the first main surface, the amount of protrusion of the first joint on one side in the second direction increases. When the surface of the first joint on one side in the second direction is positioned on the other side in the second direction of the second main surface, the amount of protrusion of the first joint on the other side in the second direction increases. Therefore, by positioning one side of the first joint in the second direction on the other side of the first main surface in the second direction, and on one side of the second main surface in the second direction, the amount of protrusion of the first joint in the second direction can be suppressed. Since the first joint is the part that overlaps with the second joint in the second direction, suppressing the amount of protrusion of the first joint in the second direction can suppress the increase in thickness of the overlapping portion (joint portion) of the first and second current collectors in the second direction. This allows for more space to be secured for the electrode body, thereby improving the volume occupancy rate of the electrode body.

[0012] The second main body has a third main surface on one side in the second direction and a fourth main surface on the other side in the second direction, and the other side of the second joint in the second joint may be positioned on the other side of the second direction than the third main surface and on one side of the second direction than the fourth main surface.

[0013] In the second current collector, when the surface on the other side in the second direction of the second joint portion is disposed on one side in the second direction with respect to the third main surface of the second main body portion, the amount of protrusion of the second joint portion to one side in the second direction increases. When the surface on the other side in the second direction of the second joint portion is disposed on the other side in the second direction with respect to the fourth main surface of the second main body portion, the amount of protrusion of the second joint portion to the other side in the second direction increases. Therefore, by disposing the surface on the other side in the second direction of the second joint portion on the other side in the second direction with respect to the third main surface and on one side in the second direction with respect to the fourth main surface, the amount of protrusion of the second joint portion in the second direction can be suppressed. Since the second joint portion is a portion that overlaps with the first joint portion in the second direction, if the amount of protrusion of the second joint portion in the second direction can be suppressed, an increase in the thickness in the second direction of the overlapping portion (joint portion) of the first current collector and the second current collector can be suppressed. Thereby, more space for disposing the electrode body can be secured, and thus the volume occupancy rate of the electrode body can be further improved.

[0014] The first joint portion may be thinner than the first main body portion in the second direction.

[0015] According to this, in the first current collector, by making the first joint portion thinner than the first main body portion, the protrusion of the first joint portion in the second direction can be further suppressed. Therefore, an increase in the thickness in the second direction of the overlapping portion (joint portion) of the first current collector and the second current collector can be further suppressed, and the volume occupancy rate of the electrode body can be improved.

[0016] The electrode terminal penetrates through the first main body portion or the second main body portion and protrudes from the first main body portion or the second main body portion to the other side in the second direction, and has a protruding portion joined to the first main body portion or the second main body portion. The surface on the other side in the second direction of the first joint portion may be disposed on one side in the second direction with respect to the end surface on the other side in the second direction of the protruding portion.

[0017] According to this, since the surface on the other side in the second direction at the first joint portion of the first current collector is arranged on the one side in the second direction with respect to the end surface of the protruding portion of the electrode terminal, it is possible to suppress the first joint portion from protruding to the other side in the second direction. Therefore, more space for arranging the electrode body can be secured, and thus the volume occupancy rate of the electrode body can be further improved.

[0018] The surface on the other side in the second direction at the first joint portion may be arranged at the same position as the second main surface in the second direction or on the one side in the second direction with respect to the second main surface.

[0019] According to this, in the first current collector, since the surface on the other side in the second direction of the first joint portion is arranged at the same position as the second main surface in the second direction or on the one side in the second direction with respect to the second main surface, it is possible to suppress the first joint portion from protruding to the other side in the second direction. Therefore, more space for arranging the electrode body can be secured, and thus the volume occupancy rate of the electrode body can be further improved.

[0020] The electrode body has an electrode body main body portion and a tab that protrudes from the electrode body main body portion and is joined to the first current collector, and the tab may be joined to the second main surface in the second direction.

[0021] According to this, the electrode body has an electrode body main body portion and a tab, and the tab is joined to the second main surface of the first main body portion of the first current collector. That is, when the electrode body has a tab, by dividing the current collector into a first current collector and a second current collector and joining the tab to the second main surface of the first main body portion of the first current collector, it becomes easier to join the tab of the electrode body to the current collector. However, if the thickness in the second direction of the overlapping portion (joint portion) of the first current collector and the second current collector is large, the space for arranging the electrode body main body portion is limited, and the volume occupancy rate of the electrode body may decrease. Therefore, by suppressing the thickness in the second direction of the overlapping portion (joint portion) of the first current collector and the second current collector from increasing, more space for arranging the electrode body main body portion can be secured. Thereby, the volume occupancy rate of the electrode body can be further improved.

[0022] The following description of an energy storage element according to an embodiment (including its modifications) of the present invention will be given with reference to the drawings. The embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement and connection configurations of components, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples only and are not intended to limit the present invention. Dimensions in each figure are not precisely illustrated. In each figure, the same or similar components are denoted by the same reference numerals.

[0023] In the following description and drawings, the direction in which the pair of electrode terminals (positive and negative, hereinafter the same) of the energy storage element are aligned, the direction in which the pair of current collectors are aligned, or the direction in which the short sides of the container face each other is defined as the X-axis direction. The direction in which the long sides of the container face each other, or the thickness direction of the container or electrode body is defined as the Y-axis direction. The direction in which the current collector and electrode body are aligned, the direction in which the electrode terminals and electrode body are aligned, the direction in which the container body and lid of the energy storage element are aligned, or the vertical direction is defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Note that depending on the usage, the Z-axis direction may not be the vertical direction, but for the sake of explanation below, the Z-axis direction will be described as the vertical direction.

[0024] In the following explanation, the X-axis positive direction refers to the direction of the X-axis arrow, and the X-axis negative direction refers to the opposite direction. When simply referred to as the X-axis direction, it refers to either the X-axis positive direction or the X-axis negative direction, or either direction. The same applies to the Y-axis and Z-axis directions. In the following, the X-axis direction may also be referred to as the first direction, and the Z-axis direction as the second direction. The Z-axis positive direction may also be referred to as one side of the second direction, and the Z-axis negative direction as the other side of the second direction. Expressions indicating relative directions or orientations, such as parallel and orthogonal, may include cases where they are not strictly those directions or orientations. For example, two directions being parallel means not only that the two directions are perfectly parallel, but also that they are substantially parallel, i.e., they may have a difference of, for example, a few percent. Furthermore, in the following explanation, when the term "insulation" is used, it means "electrical insulation."

[0025] (Embodiment) [1. General description of the energy storage element 10] First, a general description of the energy storage element 10 in this embodiment will be given. Figure 1 is a perspective view showing the external appearance of the energy storage element 10 according to this embodiment. Figure 2 is an exploded perspective view showing the individual components of the energy storage element 10 according to this embodiment.

[0026] The energy storage element 10 is a secondary battery (single cell) capable of charging and discharging electricity, and specifically, is a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is used for power storage or power supply purposes. Specifically, the energy storage element 10 is used as a battery for driving or starting the engine of mobile vehicles such as automobiles, motorcycles, watercraft, ships, snowmobiles, agricultural machinery, construction machinery, or railway vehicles for electric railways. Examples of automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicles. Examples of railway vehicles for electric railways include electric trains, monorails, maglev trains, and hybrid trains equipped with both diesel engines and electric motors. The energy storage element 10 can also be used as a stationary battery for household or commercial use.

[0027] The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery, but may be a secondary battery other than a non-aqueous electrolyte secondary battery, or a capacitor. The energy storage element 10 may not be a secondary battery, but a primary battery that allows the user to use the stored electricity without charging. The energy storage element 10 may be a battery using a solid electrolyte. The energy storage element 10 may be a pouch-type energy storage element. In this embodiment, the energy storage element 10 is shown in a flat rectangular parallelepiped shape (square, prism), but the shape of the energy storage element 10 is not limited to a rectangular parallelepiped shape, but may be cylindrical, oblong cylindrical, elliptical, or a polygonal prism shape other than a rectangular parallelepiped.

[0028] As shown in Figure 1, the energy storage element 10 comprises a container 100, a pair of electrode terminals 200 (positive and negative), and a pair of upper gaskets 300 (positive and negative). As shown in Figure 2, a pair of lower gaskets 400 (positive and negative), a pair of current collectors 500 (positive and negative), and an electrode body 600 are housed inside the container 100. An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but it is not shown in the illustration. There are no particular restrictions on the type of electrolyte as long as it does not impair the performance of the energy storage element 10, and various types can be selected. In addition to the above components, a backing plate that sandwiches the electrode body 600 between the current collector 500, a spacer placed to the side or below the electrode body 600, an insulating film that encloses the electrode body 600, etc. may also be arranged.

[0029] The container 100 is a rectangular parallelepiped (square or box-shaped) case having a container body 110 with an opening formed therein 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 constitutes the main body of the container 100. The container body 110 has a pair of short sides on both sides in the X-axis direction, a pair of long sides on both sides in the Y-axis direction, and a bottom surface on the Z-axis negative side. The lid 120 is a rectangular plate-shaped member that is long in the X-axis direction and constitutes the lid of the container 100, and is positioned in the Z-axis positive direction of the container body 110. The lid 120 is provided with an injection section 121 for injecting electrolyte into the container 100, and a gas discharge valve 122 for releasing pressure when the pressure inside the container 100 rises excessively.

[0030] With this configuration, the container 100 is sealed inside by welding or other means to the container body 110 and the lid 120 after the electrode body 600 and the lid 120 have been placed inside the container body 110. The material of the container 100 (container body 110 and lid 120) is not particularly limited and can be made of weldable metals such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet, but resin can also be used.

[0031] The electrode body 600 is an energy storage element (power generation element) that comprises a positive electrode plate, a negative electrode plate, and a separator, and is capable of storing electricity. The electrode body 600 is formed by winding layers of material arranged so that a separator is sandwiched between the positive electrode plate and the negative electrode plate. As a result, multiple tabs of the positive electrode plate are stacked to form a positive electrode tab bundle 610, and multiple tabs of the negative electrode plate are stacked to form a negative electrode tab bundle 620. In other words, the electrode body 600 has an electrode body main body portion 601 and tab bundles 610 and 620 that protrude from a part of the electrode body main body portion 601 in the Z-axis positive direction and extend in the Y-axis positive direction. In this embodiment, the electrode body 600 is an oval-shaped wound electrode body when viewed from the Z-axis direction, but it may be elliptical, circular, or any other shape when viewed from the Z-axis direction. A detailed explanation of the configuration of the electrode body 600 will be given later.

[0032] The electrode terminals 200 are terminal members (positive and negative terminals) that are electrically connected to the electrode body 600 via the current collector 500. The electrode terminals 200 are metallic members that lead the electricity stored in the electrode body 600 to the external space of the energy storage element 10 and introduce electricity into the internal space of the energy storage element 10 in order to store electricity in the electrode body 600. The electrode terminals 200 are made of a conductive material such as aluminum, aluminum alloy, copper, or copper alloy. The electrode terminals 200 are connected (joined) to the current collector 500 by crimping or the like and are attached to the cover 120.

[0033] Specifically, the electrode terminal 200 has a shaft portion 210 (rivet portion) extending downward (in the negative Z-axis direction). The shaft portion 210 is inserted into the through hole 310 of the upper gasket 300, the through hole 123 of the cover 120, the through hole 410 of the lower gasket 400, and the through hole 523 of the current collector 500 (second current collector 520), and crimped. In this way, the electrode terminal 200 is fixed to the cover 120 together with the upper gasket 300, the lower gasket 400, and the current collector 500 (second current collector 520). The method of connecting (joining) the electrode terminal 200 and the current collector 500 (second current collector 520) is not limited to crimping, and welding methods such as ultrasonic welding, laser welding or resistance welding, or mechanical joining other than crimping, such as screw joining, may be used.

[0034] The current collector 500 is a current collecting member (positive electrode current collector and negative electrode current collector) that electrically connects the electrode body 600 and the electrode terminal 200. The positive electrode current collector 500 is connected (joined) to the positive electrode tab bundle 610 of the electrode body 600 by welding or the like, and as described above, it is joined to the positive electrode terminal 200 by crimping or the like. The negative electrode current collector 500 is connected (joined) to the negative electrode tab bundle 620 of the electrode body 600 by welding or the like, and as described above, it is joined to the negative electrode terminal 200 by crimping or the like. In this embodiment, the current collector 500 is a flat plate-shaped and rectangular member. Any welding method may be used to connect (join) the current collector 500 to the tab bundle 610 or 620, such as ultrasonic welding, laser welding or resistance welding, or mechanical joining such as crimping or screw joining may be used. The material of the current collector 500 is not particularly limited, but the positive electrode current collector 500 is made of a conductive material such as aluminum or an aluminum alloy, similar to the positive electrode substrate of the electrode body 600 described later. The negative electrode current collector 500 is made of a conductive material such as copper or a copper alloy, similar to the negative electrode substrate of the electrode body 600 described later.

[0035] Specifically, the current collector 500 has a first current collector 510 and a second current collector 520 arranged side by side in the X-axis direction (first direction) and joined to each other. The first current collector 510 and the second current collector 520 are members that are joined to one and the other of the electrode body 600 and the electrode terminal 200. In other words, the current collector 500 is divided into two members, the first current collector 510 and the second current collector 520, with one member connected to the electrode body 600 and the other member connected to the electrode terminal 200. To put it another way, the first current collector 510 is joined to one of the electrode body 600 and the electrode terminal 200, but not to the other, and the second current collector 520 is joined to the other of the electrode body 600 and the electrode terminal 200, but not to the other.

[0036] In this embodiment, the first current collector 510 is joined to the electrode body 600 but not to the electrode terminal 200, and the second current collector 520 is joined to the electrode terminal 200 but not to the electrode body 600. Specifically, in the positive electrode current collector 500, the first current collector 510 is joined to the tab bundle 610 of the electrode body 600 by welding or the like, and the second current collector 520 is joined to the positive electrode terminal 200 by crimping or the like. In the negative electrode current collector 500, the first current collector 510 is joined to the tab bundle 620 of the electrode body 600 by welding or the like, and the second current collector 520 is joined to the negative electrode terminal 200 by crimping or the like. A detailed explanation of the configuration of the current collector 500 (first current collector 510 and second current collector 520) will be given later.

[0037] The upper gasket 300 is a flat plate-shaped insulating member (gasket) placed between the lid 120 of the container 100 and the electrode terminal 200, and provides insulation between the lid 120 and the electrode terminal 200. The lower gasket 400 is a flat plate-shaped insulating member (gasket) placed between the lid 120 and the current collector 500, and provides insulation between the lid 120 and the current collector 500. The upper gasket 300 and lower gasket 400 are formed from insulating resins such as polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), ABS resin, or composite materials thereof.

[0038] [2. Description of the configuration of electrode body 600] Next, the configuration of the electrode body 600 will be described in detail. Figure 3 is a perspective view showing the configuration of the electrode body 600 according to this embodiment. Specifically, Figure 3(a) shows the configuration of the electrode body 600 shown in Figure 2 with a portion of the winding state unfolded, and Figure 3(b) shows the configuration of the electrode body 600 after winding.

[0039] As shown in Figure 3(a), the electrode body 600 is formed by alternately stacking and winding a positive electrode plate 640, a negative electrode plate 650, and separators 661 and 662. In other words, the electrode body 600 is formed by stacking and winding the positive electrode plate 640, separator 661, negative electrode plate 650, and separator 662 in this order.

[0040] The positive electrode plate 640 is an electrode plate in which a positive electrode active material layer is formed on the surface of a positive electrode substrate, which is a long, strip-shaped metal foil made of aluminum or an aluminum alloy. The negative electrode plate 650 is an electrode plate in which a negative electrode active material layer is formed on the surface of a negative electrode substrate, which is a long, strip-shaped metal foil made of copper or a copper alloy. As the positive electrode substrate and the negative electrode substrate, any known material that is stable against oxidation-reduction reactions during charging and discharging can be used, such as nickel, iron, stainless steel, titanium, calcined carbon, conductive polymer, conductive glass, and Al-Cd alloy. As 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, any known material that is capable of intercalating and releasing lithium ions can be used. Separators 661 and 662 are microporous sheets made of resin. As the material for separators 661 and 662, any known material can be used, as long as it does not impair the performance of the energy storage element 10.

[0041] The positive electrode plate 640 has a plurality of rectangular tabs 641 protruding in the positive Z-axis direction at its end in the positive Z-axis direction, and the plurality of tabs 641 are arranged in a stacked state in the Y-axis direction. Similarly, the negative electrode plate 650 has a plurality of rectangular tabs 651 protruding in the positive Z-axis direction at its end in the positive Z-axis direction, and the plurality of tabs 651 are arranged in a stacked state in the Y-axis direction. Tabs 641 and 651 are portions where the active material layer is not formed and the substrate is exposed. The shape of tabs 641 and 651 is not particularly limited.

[0042] As shown in Figure 3(b), multiple stacked tabs 641 are bundled together to form a tab bundle 610 that extends in a state protruding in the positive Z-axis direction. Similarly, multiple stacked tabs 651 are bundled together to form a tab bundle 620 that extends in a state protruding in the positive Z-axis direction. These tab bundles 610 and 620 are joined to the current collector 500 (first current collector 510) in a state where they are overlapped with the current collector 500 (first current collector 510) in the Y-axis direction, and then bent together with the current collector 500 (first current collector 510) in the positive Y-axis direction. As a result, the tab bundles 610 and 620 are in a state where they are overlapped with the current collector 500 (first current collector 510) and joined to the current collector 500 (first current collector 510) in the Z-axis direction.

[0043] The electrode body portion 601 is the part that constitutes the main body of the electrode body 600, and specifically, it is the part of the electrode body 600 other than the tab bundles 610 and 620. The electrode body portion 601 is an elongated cylindrical or oval-shaped portion formed by winding the portions on which the active material layer of the positive electrode plate 640 and the negative electrode plate 650 is formed with the separators 661 and 662. If the electrode body 600 has an active material non-formed portion (uncoated active material portion) at the end of the electrode plate (positive electrode plate 640 or negative electrode plate 650) where the active material layer is not formed, and tabs (tabs 641 or 651) extend from the active material non-formed portion, then the electrode body portion 601 also includes the active material non-formed portion. In this case, the tab bundle 610 (or 620) is a portion in which multiple tabs 641 (or multiple tabs 651) are stacked, and does not include the active material non-formed portion.

[0044] [3. Explanation of current collector 500] Next, the configuration of the current collector 500 (first current collector 510 and second current collector 520) will be explained in detail. The configuration of the positive electrode current collector 500 (in the negative X-axis direction) and its surroundings shown in Figure 2, and the configuration of the negative electrode current collector 500 (in the positive X-axis direction) and its surroundings have the same configuration (a configuration rotated 180° around the Z-axis). For this reason, the configuration of the positive electrode current collector 500 and its surroundings will be explained below, and the explanation of the negative electrode current collector 500 and its surroundings will be omitted.

[0045] Figure 4 is a perspective view showing the configuration of the current collector 500 (first current collector 510 and second current collector 520) according to this embodiment. Specifically, Figure 4(a) is a perspective view showing the positive electrode (in the negative X-axis direction) current collector 500 shown in Figure 2, with the first current collector 510 and the second current collector 520 separated. Figure 4(b) is a perspective view showing the configuration of Figure 4(a) viewed from diagonally below. Figure 5 is a cross-sectional view showing the current collector 500 (first current collector 510 and second current collector 520) according to this embodiment joined to the electrode terminal 200 and the electrode body 600. Specifically, Figure 5(a) shows the configuration of the positive electrode (in the negative X-axis direction) current collector 500, the electrode terminal 200 and the electrode body 600, etc., and Figure 5(b) shows an enlarged view of the configuration within the dashed line in Figure 5(a).

[0046] As shown in Figures 4 and 5, the current collector 500 has a first current collector 510 and a second current collector 520 that are aligned in the X-axis direction (first direction) and joined to each other. The first current collector 510 and the second current collector 520 are flat plate-shaped members parallel to the XY plane. The first current collector 510 has a first main body portion 511 and a first joint portion 512 that protrudes from the first main body portion 511 toward the second current collector 520 in the negative X-axis direction. The second current collector 520 has a second main body portion 521 and a second joint portion 522 that protrudes from the second main body portion 521 toward the first current collector 510 in the positive X-axis direction.

[0047] The first main body portion 511 is a flat, rectangular portion parallel to the XY plane and is joined to one of the electrode body 600 and the electrode terminal 200. In this embodiment, the first main body portion 511 is joined to the tab bundle 610 (tab 641) of the electrode body 600. The first main body portion 511 has a first main surface 511a in the Z-axis positive direction (one side of the second direction) and a second main surface 511b in the Z-axis negative direction (the other side of the second direction).

[0048] The first main surface 511a is a plane (flat surface) parallel to the XY plane provided on the upper surface of the first main body 511. The first main surface 511a is positioned in the negative Z-axis direction of the lower gasket 400 and contacts the lower gasket 400 in the Z-axis direction. In this embodiment, the entire surface of the first main surface 511a is in contact with the lower gasket 400, but a part of it may not be in contact with the lower gasket 400, or it may be positioned at a distance from the lower gasket 400.

[0049] The second main surface 511b is a plane (flat surface) parallel to the XY plane, provided on the lower surface of the first main body 511. The second main surface 511b is positioned in the Z-axis positive direction of the tab bundle 610 (tabs 641) of the electrode body 600, and is joined to the tab bundle 610 (tabs 641) in the Z-axis direction (second direction). The joining position of the second main surface 511b with the tab bundle 610 may be the central part (center position) of the second main surface 511b when viewed from the Z-axis direction, or it may be the end of the second main surface 511b, and is not particularly limited.

[0050] The first joint portion 512 is a long, flat plate-shaped portion that extends in the Y-axis direction and is parallel to the XY plane, extending from one end in the Y-axis direction to the other end of the first main body portion 511. The first joint portion 512 is the portion that is joined to the second joint portion 522 of the second current collector 520. The first joint portion 512 has a first joint surface 512a in the Z-axis positive direction (one side of the second direction) and a first opposing surface 512b in the Z-axis negative direction (the other side of the second direction).

[0051] The first joint surface 512a is a plane (flat surface) provided on the upper surface of the first joint 512 that is parallel to the XY plane and extends in the Y-axis direction. The first joint surface 512a is positioned in the negative Z-axis direction of the second joint 522 of the second current collector 520 and is joined to the second joint 522 in the Z-axis direction. In other words, the first joint 512 is positioned in the negative Z-axis direction of the second joint 522 of the second current collector 520 and is joined to the second joint 522 in the Z-axis direction. The first joint 512 may be joined to the second joint 522 from one end to the other in the Y-axis direction of the first joint surface 512a, or it may be joined to the second joint 522 at the center or end in the Y-axis direction of the first joint surface 512a, and the joining position is not particularly limited.

[0052] The first joint surface 512a is positioned in the Z-axis direction (second direction) further in the negative Z-axis direction (the other side of the second direction) than the first main surface 511a, and further in the Z-axis direction (one side of the second direction) than the second main surface 511b. If the first main surface 511a, the second main surface 511b, or the first joint surface 512a is not a plane (flat surface), the part of the first joint surface 512a that is furthest in the Z-axis direction will be positioned in the Z-axis direction (negative Z-axis direction) than the part of the first main surface 511a that is furthest in the Z-axis direction (negative Z-axis direction). Furthermore, in this case, the part of the first joint surface 512a that is furthest in the Z-axis direction will be positioned in the Z-axis direction (positive Z-axis direction) than the part of the second main surface 511b that is furthest in the Z-axis direction (negative Z-axis direction).

[0053] Thus, the first joint surface 512a is positioned in the Z-axis direction between the first main surface 511a and the second main surface 511b (excluding the positions of the first and second main surfaces 511a and 511b). In other words, the first joint surface 512a is positioned such that the distance to the first main surface 511a and the distance to the second main surface 511b are smaller than the distance between the first and second main surfaces 511a and 511b. In this embodiment, the first joint surface 512a is positioned in the Z-axis direction at an intermediate position (center position) between the first and second main surfaces 511a and 511b.

[0054] The first opposing surface 512b is a plane (flat surface) provided on the lower surface of the first joint 512 that is parallel to the XY plane and extends in the Y-axis direction. In other words, the first opposing surface 512b is one of the surfaces of the first joint 512 that faces the first joint surface 512a in the Z-axis direction. The first opposing surface 512b is located at the same position as the second main surface 511b in the Z-axis direction (second direction), or is located further in the positive Z-axis direction (one side of the second direction) than the second main surface 511b. If the second main surface 511b or the first opposing surface 512b is not a plane (flat surface), the part of the first opposing surface 512b that is located furthest in the negative Z-axis direction is located at the same position as the part of the second main surface 511b that is located furthest in the negative Z-axis direction, or is located further in the positive Z-axis direction than that part of the second main surface 511b. In this embodiment, the first opposing surface 512b is located at the same position as the second main surface 511b in the Z-axis direction. As a result, the first opposing surface 512b, together with the second main surface 511b, forms a plane (flat surface) parallel to the XY plane provided on the lower surface of the first current collector 510.

[0055] With this configuration, the first joint portion 512 is thinner than the first main body portion 511 in the Z-axis direction (second direction). In other words, the first joint portion 512 is positioned to protrude in the X-axis direction from the Z-axis negative end of the first main body portion 511. To put it another way, the first current collector 510 has a stepped shape that descends from the first main body portion 511 to the first joint portion 512. It can also be said that the first current collector 510 has a shape in which the corners in the X-axis negative direction and Z-axis positive direction are recessed in the X-axis positive direction and Z-axis negative direction at the position of the first joint portion 512. In this embodiment, the thickness of the first joint portion 512 in the Z-axis direction is about half the thickness of the first main body portion 511 in the Z-axis direction.

[0056] The second main body portion 521 is a flat, rectangular portion parallel to the XY plane and is joined to the other side of the electrode body 600 and electrode terminal 200. In this embodiment, the second main body portion 521 has the aforementioned through hole 523 and is joined to the electrode terminal 200. Specifically, as shown in Figure 5, the shaft portion 210 of the electrode terminal 200 is crimped at the Z-axis negative end of the shaft portion 210 with the shaft portion 210 passing through the through hole 523 of the second main body portion 521 in the Z-axis direction. As a result, a protrusion 211 (crimped portion) is formed at the Z-axis negative end of the shaft portion 210, and the electrode terminal 200 and the second current collector 520 (second main body portion 521) are joined. Thus, the protrusion 211 is a portion (crimped portion) that passes through the second main body portion 521, protrudes from the second main body portion 521 in the Z-axis negative direction (the other side of the second direction), and is joined to the second main body portion 521.

[0057] The second main body portion 521 has a third main surface 521a in the Z-axis positive direction (one side of the second direction) and a fourth main surface 521b in the Z-axis negative direction (the other side of the second direction). In other words, a through hole 523 is formed extending from the third main surface 521a to the fourth main surface 521b so as to penetrate both the third main surface 521a and the fourth main surface 521b.

[0058] The third main surface 521a is a plane (flat surface) parallel to the XY plane provided on the upper surface of the second main body 521. The third main surface 521a is positioned in the negative Z-axis direction of the lower gasket 400, and at least a portion of it is in contact with the lower gasket 400 in the Z-axis direction. The third main surface 521a may be positioned spaced apart from the lower gasket 400.

[0059] The fourth main surface 521b is a plane (flat surface) parallel to the XY plane, provided on the lower surface of the second main body 521. The fourth main surface 521b is positioned in the Z-axis positive direction of the projection 211 of the shaft portion 210 of the electrode terminal 200, and contacts the projection 211 in the Z-axis direction. The fourth main surface 521b contacts the projection 211 on the surface surrounding the through hole 523, but depending on the shape of the projection 211, it may also contact the projection 211 on surfaces other than the surface surrounding the through hole 523.

[0060] The second joint portion 522 is a long, flat plate-shaped portion that extends in the Y-axis direction and is parallel to the XY plane, extending from one end in the Y-axis direction to the other end of the second main body portion 521, projecting in the X-axis direction from the X-axis positive end. The second joint portion 522 is positioned in the Z-axis positive direction of the first joint portion 512 of the first current collector 510. Specifically, the second joint portion 522 is superimposed on the Z-axis positive direction (one side of the second direction) of the first joint portion 512 and joined to the first joint portion 512. The second joint portion 522 has a second opposing surface 522a in the Z-axis positive direction (one side of the second direction) and a second joining surface 522b in the Z-axis negative direction (the other side of the second direction).

[0061] The second joint surface 522b is a plane (flat surface) provided on the lower surface of the second joint portion 522 that is parallel to the XY plane and extends in the Y-axis direction. The second joint surface 522b is positioned in the Z-axis positive direction of the first joint surface 512a of the first joint portion 512 of the first current collector 510, and is positioned opposite the first joint surface 512a in the Z-axis direction. As described above, since the second joint portion 522 is joined to the first joint portion 512, the second joint surface 522b is joined to the first joint surface 512a in the Z-axis direction.

[0062] The second joint surface 522b is positioned in the Z-axis direction (second direction) further in the negative Z-axis direction (on the other side of the second direction) than the third principal surface 521a, and further in the Z-axis direction (on one side of the second direction) than the fourth principal surface 521b. If the third principal surface 521a, the fourth principal surface 521b, or the second joint surface 522b is not a plane (flat surface), the part of the second joint surface 522b that is furthest in the Z-axis direction will be positioned in the Z-axis direction (negative Z-axis direction) than the part of the third principal surface 521a that is furthest in the Z-axis direction (negative Z-axis direction). Furthermore, in this case, the part of the second joint surface 522b that is furthest in the Z-axis direction will be positioned in the Z-axis direction (positive Z-axis direction) than the part of the fourth principal surface 521b that is furthest in the Z-axis direction (negative Z-axis direction).

[0063] Thus, the second joining surface 522b is positioned in the Z-axis direction between the third principal surface 521a and the fourth principal surface 521b (excluding the positions of the third principal surface 521a and the fourth principal surface 521b). In other words, the second joining surface 522b is positioned closer to the fourth principal surface 521b than to the third principal surface 521a, and closer to the third principal surface 521a than to the fourth principal surface 521b. To put it another way, the second joining surface 522b is positioned such that the distance to the third principal surface 521a and the distance to the fourth principal surface 521b are smaller than the distance between the third principal surface 521a and the fourth principal surface 521b. In this embodiment, the second joining surface 522b is positioned in the Z-axis direction at an intermediate position (center position) between the third principal surface 521a and the fourth principal surface 521b.

[0064] The second opposing surface 522a is a plane (flat surface) provided on the upper surface of the second joint 522 that is parallel to the XY plane and extends in the Y-axis direction. In other words, the second opposing surface 522a is the surface of the second joint 522 that faces the second joint surface 522b in the Z-axis direction. The second opposing surface 522a is located at the same position as the third main surface 521a in the Z-axis direction (second direction), or at a position further in the negative Z-axis direction (the other side of the second direction) than the third main surface 521a. If the third main surface 521a or the second opposing surface 522a is not a plane (flat surface), the part of the second opposing surface 522a that is furthest in the positive Z-axis direction is located at the same position as the part of the third main surface 521a that is furthest in the positive Z-axis direction, or at a position further in the negative Z-axis direction than that part of the third main surface 521a. In this embodiment, the second opposing surface 522a is located at the same position as the third main surface 521a in the Z-axis direction. As a result, the second opposing surface 522a, together with the third main surface 521a, forms a plane (flat surface) parallel to the XY plane provided on the upper surface of the second current collector 520.

[0065] With this configuration, the second joint portion 522 is thinner than the second main body portion 521 in the Z-axis direction (second direction). In other words, the second joint portion 522 is positioned to protrude in the X-axis direction from the Z-axis positive end of the second main body portion 521. To put it another way, the second current collector 520 has a shape in which the corners in the X-axis positive direction and Z-axis negative direction are recessed in the X-axis negative direction and Z-axis positive direction at the position of the second joint portion 522. In this embodiment, the thickness of the second joint portion 522 in the Z-axis direction is about half the thickness of the second main body portion 521 in the Z-axis direction.

[0066] In this embodiment, in the first current collector 510 and the second current collector 520, the first main body portion 511 and the second main body portion 521 have the same thickness in the Z-axis direction, and the first joint portion 512 and the second joint portion 522 also have the same thickness in the Z-axis direction. As a result, the first main surface 511a and the third main surface 521a are positioned at the same location in the Z-axis direction, and the second main surface 511b and the fourth main surface 521b are also positioned at the same location in the Z-axis direction. The first joint surface 512a is positioned in the Z-axis direction more negative than the third main surface 521a and more positive than the fourth main surface 521b. The first opposing surface 512b is positioned in the Z-axis direction at the same location as the fourth main surface 521b (or more positive than the fourth main surface 521b). The second joining surface 522b is positioned in the Z-axis direction more negative than the first main surface 511a, and in the Z-axis direction more positive than the second main surface 511b. The second opposing surface 522a is positioned in the Z-axis direction at the same position as the first main surface 511a (or in the Z-axis direction more negative than the first main surface 511a).

[0067] Since the protruding portion 211 of the shaft portion 210 of the electrode terminal 200 protrudes from the second main body portion 521 in the negative Z-axis direction, the fourth main surface 521b is positioned in the positive Z-axis direction more than the end face 211a of the protruding portion 211 in the negative Z-axis direction (see Figure 5(b)). For this reason, the first opposing surface 512b is positioned in the positive Z-axis direction (one side of the second direction) more than the end face 211a of the protruding portion 211 in the negative Z-axis direction (the other side of the second direction). In this embodiment, the end face 211a is a plane (flat surface) parallel to the XY plane, but if the end face 211a is not a plane (flat surface), the first opposing surface 512b is positioned in the positive Z-axis direction more than the part of the end face 211a that is furthest in the negative Z-axis direction.

[0068] During the manufacturing of the energy storage element 10, the first current collector 510 and the second current collector 520 are separated. The tab bundle 610 of the electrode body 600 is joined to the first main body 511 of the first current collector 510 by welding or the like, and the electrode terminals 200 are joined to the second main body 521 of the second current collector 520 by crimping or the like. Then, the first joint portion 512 of the first current collector 510 and the second joint portion 522 of the second current collector 520 are superimposed in the Z-axis direction, and a laser beam L (see Figure 5(b)) is shone from the negative Z-axis direction toward the first joint portion 512 at the position where the first joint portion 512 and the second joint portion 522 are superimposed. As a result, the first joint portion 512 and the second joint portion 522 are laser-welded, and the first current collector 510 and the second current collector 520 are joined together.

[0069] With this configuration, the first current collector 510 is connected to the electrode body 600 without being connected to the electrode terminal 200, and the second current collector 520 is connected to the electrode terminal 200 without being connected to the electrode body 600. Furthermore, the first joint portion 512 and the second joint portion 522 are connected at positions different from the connection positions of the first main body portion 511 and the electrode body 600, and are not connected at those connection positions. Similarly, the first joint portion 512 and the second joint portion 522 are connected at positions different from the connection positions of the second main body portion 521 and the electrode terminal 200, and are not connected at those connection positions. Thus, the first current collector 510 and the second current collector 520 are not connected at the connection positions with the electrode body 600 and the electrode terminal 200.

[0070] [4. Explanation of Effects] As described above, according to the energy storage element 10 of the present invention, the current collector 500 has a first current collector 510 joined to one of the electrode body 600 and electrode terminal 200 (electrode body 600), and a second current collector 520 joined to the other (electrode terminal 200). The second joint portion 522 of the second current collector 520 is superimposed and joined to the first joint portion 512 of the first current collector 510 in the Z-positive direction (one side of the second direction). The first joint surface 512a of the first joint portion 512, which is the Z-positive direction surface, is positioned in the Z-negative direction (the other side of the second direction) than the first main surface 511a of the first main body portion 511 of the first current collector 510 in the Z-positive direction, in the Z-axis direction (second direction). Furthermore, the first joint surface 512a is positioned in the Z-positive direction than the second main surface 511b of the first main body portion 511 in the Z-negative direction. Thus, in the first current collector 510, the first joint surface 512a of the first joint portion 512 is positioned in the negative Z-axis direction more than the first main surface 511a of the first body portion 511, and in the positive Z-axis direction more than the second main surface 511b. When the first joint surface 512a of the first joint portion 512 is positioned in the positive Z-axis direction more than the first main surface 511a, the amount of protrusion of the first joint portion 512 in the positive Z-axis direction increases. When the first joint surface 512a of the first joint portion 512 is positioned in the negative Z-axis direction more than the second main surface 511b, the amount of protrusion of the first joint portion 512 in the negative Z-axis direction increases. For this reason, by positioning the first joint surface 512a of the first joint portion 512 in the negative Z-axis direction more than the first main surface 511a, and in the positive Z-axis direction more than the second main surface 511b, the amount of protrusion of the first joint portion 512 in the Z-axis direction can be suppressed. Since the first joint portion 512 overlaps with the second joint portion 522 in the Z-axis direction, suppressing the amount of protrusion of the first joint portion 512 in the Z-axis direction will suppress the increase in thickness in the Z-axis direction of the overlapping portion (joint portion) of the first current collector 510 and the second current collector 520. This will allow for more space to be secured for the electrode body 600, thereby improving the volume occupancy rate of the electrode body 600.

[0071] By joining the first joint 512 and the second joint 522 in the Z-axis direction, even when laser welding the first joint 512 and the second joint 522 by irradiating them with laser light L from the Z-axis direction, it is possible to suppress the laser light L from passing through the current collector 500 between the first joint 512 and the second joint 522 and affecting other components (such as the lower gasket 400). Furthermore, by dividing the current collector 500 into a first current collector 510 that is joined to the electrode body 600 and a second current collector 520 that is joined to the electrode terminal 200, the following effects are achieved. The joining work (ultrasonic joining, etc.) between the electrode body 600 and the first current collector 510 can be performed with the first current collector 510 separated from the cover 120, making the joining work easier. In particular, contamination generated during the joining work can be prevented from adhering to the cover 120, thus suppressing the occurrence of defects caused by contamination. The connection between the electrode terminal 200 and the second current collector 520 can be easily performed, and the lid 120 of the container 100 can be cleaned while the second current collector 520 is fixed to the lid 120.

[0072] In the second current collector 520, if the second joint surface 522b of the second joint portion 522, which is the surface in the negative Z-axis direction (the other side of the second direction), is positioned in the positive Z-axis direction (one side of the second direction) more than the third main surface 521a of the second main body portion 521, the amount of protrusion of the second joint portion 522 in the positive Z-axis direction increases. If the second joint surface 522b of the second joint portion 522 is positioned in the negative Z-axis direction more than the fourth main surface 521b of the second main body portion 521, the amount of protrusion of the second joint portion 522 in the negative Z-axis direction increases. Therefore, by positioning the second joint surface 522b of the second joint portion 522 in the negative Z-axis direction more than the third main surface 521a and in the positive Z-axis direction more than the fourth main surface 521b, the amount of protrusion of the second joint portion 522 in the Z-axis direction (second direction) can be suppressed. Since the second joint 522 is the part that overlaps with the first joint 512 in the Z-axis direction, if the amount of protrusion of the second joint 522 in the Z-axis direction can be suppressed, it is possible to suppress the increase in the thickness in the Z-axis direction of the overlapping portion (joint portion) of the first current collector 510 and the second current collector 520. As a result, more space can be secured for arranging the electrode body 600, and thus the volume occupancy rate of the electrode body 600 can be further improved.

[0073] In the first current collector 510, by making the first joint portion 512 thinner than the first main body portion 511, the protrusion of the first joint portion 512 in the Z-axis direction (second direction) can be further suppressed. Therefore, the thickness of the overlapping portion (joint portion) of the first current collector 510 and the second current collector 520 in the Z-axis direction can be further suppressed, and the volume occupancy rate of the electrode body 600 can be improved.

[0074] By positioning the first opposing surface 512b of the first joint portion 512 of the first current collector 510, which is the surface in the negative Z-axis direction (the other side of the second direction), in the positive Z-axis direction (one side of the second direction) than the end face 211a of the protruding portion 211 of the electrode terminal 200, the first joint portion 512 can be prevented from protruding in the negative Z-axis direction. Therefore, more space can be secured for arranging the electrode body 600, and thus the volume occupancy rate of the electrode body 600 can be further improved.

[0075] By positioning the first opposing surface 512b at the same location as the second main surface 511b in the Z-axis direction (second direction), or further in the Z-positive direction (one side of the second direction) than the second main surface 511b, the first joint portion 512 can be prevented from protruding in the Z-negative direction. Therefore, more space can be secured for arranging the electrode body 600, and thus the volume occupancy rate of the electrode body 600 can be further improved.

[0076] The electrode body 600 has an electrode body main body 601 and a tab bundle 610 (tabs 641), and the tab bundle 610 is joined to the second main surface 511b of the first main body 511 of the first current collector 510. In other words, when the electrode body 600 has a tab bundle 610, dividing the current collector 500 into a first current collector 510 and a second current collector 520 and joining the tab bundle 610 to the second main surface 511b makes it easier to join the tab bundle 610 of the electrode body 600 to the current collector 500. However, if the thickness of the overlapping portion (joining portion) of the first current collector 510 and the second current collector 520 in the Z-axis direction (second direction) is thick, the space in which the electrode body main body 601 can be placed is limited, and the volume occupancy rate of the electrode body 600 may decrease. Therefore, by suppressing the increase in thickness in the Z-axis direction of the overlapping portion (joint portion) of the first current collector 510 and the second current collector 520, more space can be secured for arranging the electrode body portion 601. This further improves the volume occupancy rate of the electrode body 600.

[0077] In the above, the effects on the positive electrode current collector 500 can be similarly applied to the negative electrode current collector 500.

[0078] [5 Explanation of variations] Although the energy storage element 10 according to this embodiment has been described above, the present invention is not limited to the above embodiment. The embodiments disclosed herein are illustrative and not restrictive in all respects, and the scope of the present invention includes all modifications in the sense and scope equivalent to the claims.

[0079] (Variation 1) In the above embodiment, the first joining surface 512a of the first current collector 510 and the second joining surface 522b of the second current collector 520 are assumed to be planes (flat surfaces) parallel to the XY plane, but the embodiment is not limited to this. Figure 6 is a cross-sectional view showing the current collector 501 according to Modification 1 of this embodiment joined to the electrode terminal 200 and the electrode body 600. Specifically, Figure 6(a) corresponds to Figure 5(a), and Figure 6(b) corresponds to Figure 5(b).

[0080] As shown in Figure 6, the first current collector 510 of the current collector 501 in Modification 1 has a first joint portion 513 having a first joint surface 513a, instead of the first joint portion 512 having a first joint surface 512a in the above embodiment. The second current collector 520 of the current collector 501 has a second joint portion 524 having a second joint surface 524b, instead of the second joint portion 522 having a second joint surface 522b in the above embodiment. The other configurations of this modification are the same as in the above embodiment.

[0081] The first joining surface 513a is an inclined surface that slopes toward the negative Z-axis direction as it moves toward the negative X-axis direction. As a result, the first joining portion 513 has a tapered shape in which the thickness in the Z-axis direction becomes thinner as it moves toward the negative X-axis direction. The second joining surface 524b is an inclined surface that slopes toward the positive Z-axis direction as it moves toward the positive X-axis direction. As a result, the second joining portion 524 has a tapered shape in which the thickness in the Z-axis direction becomes thinner as it moves toward the positive X-axis direction. The second joining surface 524b is inclined at the same angle as the first joining surface 513a, so that it contacts and is joined to the first joining surface 513a.

[0082] With this configuration, similar to the above embodiment, the first joining surface 513a is positioned in the negative Z-axis direction more than the first main surface 511a and in the positive Z-axis direction more than the second main surface 511b. The first joining portion 513 is thinner than the first main body portion 511 in the Z-axis direction. The second joining surface 524b is positioned in the negative Z-axis direction more than the third main surface 521a and in the positive Z-axis direction more than the fourth main surface 521b in the Z-axis direction. The second joining portion 524 is thinner than the second main body portion 521 in the Z-axis direction. During the manufacturing of the energy storage element 10, a laser beam L is irradiated from the negative Z-axis direction toward the first joining portion 513 at the position where the first joining portion 513 and the second joining portion 524 are overlapped, and the first joining portion 513 and the second joining portion 524 are laser welded together.

[0083] As described above, the energy storage element 10 according to this modified example can achieve the same effects as the above embodiment. In particular, in this modified example, since it is only necessary to form inclined surfaces on the first joint 513 and the second joint 524, there is no need to precisely process the thickness of the first joint 512 and the second joint 522 as in the above embodiment, making processing easier.

[0084] (Variations 2-4) In the above embodiment, the positions in the Z-axis direction of the first joining surface 512a and the first opposing surface 512b of the first current collector 510, and the second joining surface 522b of the second current collector 520, are not limited to the positions described above. Figures 7A to 7C are cross-sectional views showing the current collectors 502 to 504 according to modified examples 2 to 4 of this embodiment joined to the electrode terminals 200 and the electrode body 600. Specifically, Figures 7A to 7C correspond to Figure 5(b).

[0085] As shown in Figure 7A, the first current collector 510 of the current collector 502 in Modification 2 has a first joint 514 with a first opposing surface 514b instead of the first joint 512 with a first opposing surface 512b in the above embodiment. The first joint 514 is thicker in the Z-axis direction than the first joint 512 in the above embodiment. As a result, the first opposing surface 514b is positioned in the negative Z-axis direction more than the second main surface 511b and the fourth main surface 521b in the Z-axis direction. The first joint 514 may be thicker in the Z-axis direction than the first main body 511. The other configurations of this modification are the same as in the above embodiment.

[0086] As shown in Figure 7B, the first current collector 510 of the current collector 503 in Modification 3 has a first main body portion 515 having a second main surface 515b, instead of the first main body portion 511 having a second main surface 511b in the above embodiment. The first main body portion 515 is thicker in the Z-axis direction than the first main body portion 511 in the above embodiment. As a result, the first opposing surface 512b, like the first joining surface 512a, is positioned in the Z-axis direction more negative than the first main surface 511a and more positive than the second main surface 515b. The other configurations of this modification are the same as in the above embodiment.

[0087] As shown in Figure 7C, in the modified example 4, the first current collector 510 of the current collector 504 has a first joint portion 512 positioned at the Z-axis negative end of the first main body portion 515 in the modified example 3. The second current collector 520 of the current collector 504 has a second joint portion 525 with a second joint surface 525b instead of the second joint portion 522 with a second joint surface 522b in the above embodiment. The second joint portion 525 has a thickness in the Z-axis direction that is thicker than the second joint portion 522 in the above embodiment and the same thickness as the second main body portion 521. As a result, the second joint surface 525b is positioned in the same position as the fourth main surface 521b in the Z-axis direction. The second joint portion 525 may have a thickness in the Z-axis direction that is thicker than the second main body portion 521, and the second joint surface 525b may be positioned in the Z-axis negative direction more than the fourth main surface 521b in the Z-axis direction. In this case, the first bonding surface 512a may be positioned in the negative Z-axis direction relative to the end face 211a of the protrusion 211 of the electrode terminal 200. The other configurations of this modified example are the same as those of the embodiment described above.

[0088] As described above, the energy storage element 10 according to this modified example can achieve the same effects as the embodiment described above. As in this modified example, the first current collector 510 and the second current collector 520 of various thicknesses can be used.

[0089] (Other variations) In the above embodiment, the electrode body 600 is a wound-type electrode body with a winding axis perpendicular to the cover body 120, but it may also be a stack-type electrode body with flat plates stacked on top of each other, or a bellows-type electrode body with plates and / or separators folded in a bellows-like manner. The electrode body 600 may also be a wound-type electrode body with a winding axis parallel to the cover body 120. Instead of the tab bundles 610 and 620, the electrode body 600 may be joined to the end of the electrode body 600 that protrudes from the entire electrode body main body portion 601 of the electrode body 600.

[0090] In the above embodiment, the current collector 500 is composed of two members, a first current collector 510 and a second current collector 520, but it is not limited to this. The first current collector 510 may be composed of two members, or three or more members, including a member (such as a lead) that includes a first main body portion 511 joined to the electrode body 600, and a member that includes a first joining portion 512 joined to the second current collector 520. In this case, the first main surface 511a and the second main surface 511b are the surfaces of the lead, etc., corresponding to the first main body portion 511 described above. The same applies to the second current collector 520. The electrode body 600 may have a member (such as a lead) that is separate from the electrode body main body portion 601 and is joined to the first current collector 510. The electrode terminal 200 may have a member (such as a lead) that is separate from the terminal body and is joined to the second current collector 520.

[0091] In the above embodiment, the shaft portion 210 of the electrode terminal 200 is crimped through the through hole 523 of the second body portion 521 of the second current collector 520. However, the second body portion 521 may have a shaft portion, and this shaft portion may be crimped through the through hole of the electrode terminal 200. In this case, the second body portion 521 may have the shaft portion integrally with the second body portion 521, or it may have a separate shaft portion.

[0092] In the above embodiment, the first current collector 510 and the second current collector 520 are arranged side by side in the X-axis direction, but they may also be arranged side by side in the Y-axis direction, or in a direction between the X-axis direction and the Y-axis direction.

[0093] In the above embodiment, the first current collector 510 is joined to the electrode body 600 and the second current collector 520 is joined to the electrode terminal 200. However, the first current collector 510 may be joined to the electrode terminal 200 and the second current collector 520 may be joined to the electrode body 600. In this case, the electrode terminal 200 may have a protruding portion 211 that penetrates the first main body portion 511 of the first current collector 510, protrudes from the first main body portion 511 in the negative Z-axis direction (the other side of the second direction), and is joined to the first main body portion 511. Furthermore, the surface of the first joining portion 512 in the negative Z-axis direction (the other side of the second direction) may be positioned in the positive Z-axis direction (one side of the second direction) more than the end face 211a of the protruding portion 211 in the negative Z-axis direction (the other side of the second direction).

[0094] In the above embodiment, both the positive electrode current collector 500 and the negative electrode current collector 500 are assumed to have the above configuration, but either the positive electrode current collector 500 or the negative electrode current collector 500 does not need to have the above configuration.

[0095] The present invention also includes forms constructed by arbitrarily combining the components included in the above embodiments and their modified examples.

[0096] This invention can be realized not only as such an energy storage element, but also as a current collector. [Industrial applicability]

[0097] This invention can be applied to energy storage elements such as lithium-ion secondary batteries. [Explanation of symbols]

[0098] 10 Energy storage elements 100 containers 120 Lid 200 electrode terminal 210 Shaft section 211 Protrusion 211a End face 300 Upper gasket 400 Lower gasket 500, 501, 502, 503, 504 collector 510 First Collector 511, 515 First Body Department 511a First Main Face 511b, 515b Second Main Face 512, 513, 514 First joint 512a, 513a First mating surface 512b, 514b First Opposite Plane 520 Second Collector 521 Second Body Section 521a Third Main Face 521b Fourth Main Face 522, 524, 525 Second joint 522a Second facing side 522b, 524b, 525b Second mating surfaces 600 electrode 610, 620 beam 641, 651 タブ

Claims

1. An energy storage element comprising an electrode body, electrode terminals, and a current collector joined to the electrode body and the electrode terminals, The current collector comprises a first current collector and a second current collector arranged side by side in a first direction and joined together, The first current collector is joined to one of the electrode body and the electrode terminal, but not to the other. The second current collector is connected to the other, and not connected to the one. The first current collector has a first main body portion that is joined to the one above, and a first joining portion that is joined to the second current collector, The second current collector has a second main body that is joined to the other, and a second joint that is superimposed on one side of the first joint in a second direction intersecting the first direction and joined to the first joint, The first main body portion has a first main surface on one side in the second direction and a second main surface on the other side in the second direction. The surface on one side of the first joint in the second direction is positioned on the other side of the second direction from the first main surface, and is positioned on one side of the second direction from the second main surface. The first joint portion is thinner than the first main body portion in the second direction. Energy storage element.

2. The second main body has a third main surface on one side in the second direction and a fourth main surface on the other side in the second direction. The other side of the second joint in the second direction is positioned on the other side of the second direction than the third main surface, and on one side of the second direction than the fourth main surface. The energy storage element according to claim 1.

3. The electrode terminal has a protruding portion that penetrates the first main body or the second main body and protrudes from the first main body or the second main body to the other side in the second direction, and is joined to the first main body or the second main body, The other side of the first joint in the second direction is positioned on one side in the second direction than the other end face of the protruding portion in the second direction. The energy storage element according to claim 1 or 2.

4. The other side of the first joint in the second direction is positioned at the same location as the second main surface in the second direction, or is positioned on one side of the second main surface in the second direction. The energy storage element according to any one of claims 1 to 3.

5. The electrode body comprises an electrode body main body portion and a tab that protrudes from the electrode body main body portion and is joined to the first current collector, The tab is joined to the second main surface in the second direction. The energy storage element according to any one of claims 1 to 4.

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