Power storage element

Abstract

This power storage element comprises: a terminal; an electrode body; and a current collector connected to the terminal and the electrode body. The current collector includes a plate-like terminal connection unit connected to the terminal, and a plate-like electrode body connection unit connected to the electrode body. The electrode body includes a body section and a connection unit connected to the electrode body connection unit. The electrode body connection unit is disposed in an orientation facing the body section. The plate thickness of the terminal connection unit is less than the plate thickness of the electrode body connection unit.

Description

Energy storage element

[0001] The present invention relates to an energy storage element.

[0002] Patent Document 1 discloses a secondary battery having a current collecting terminal, the current collecting terminal having a substrate portion and a current collecting plate portion that is continuous with the substrate portion and extends in a direction perpendicular to the substrate portion, the substrate portion being connected to an external terminal, and the current collecting plate portion being connected to an electrode body.

[0003] Japanese Patent Application Laid-Open No. 2018-190546

[0004] In conventional secondary batteries such as that disclosed in Patent Document 1, a configuration is desired that allows the size of the electrode body to be increased and allows for a higher capacity.

[0005] The present invention was made by the inventors of the present application by focusing on the above-mentioned problem, and has an object to provide an energy storage element that can achieve a high capacity.

[0006] An energy storage element according to one embodiment of the present invention comprises a terminal, an electrode body, and a current collector connected to the terminal and the electrode body, the current collector comprising a plate-shaped terminal connection portion connected to the terminal and a plate-shaped electrode body connection portion connected to the electrode body, the electrode body comprising a main body portion and a connection portion connected to the electrode body connection portion, the electrode body connection portion being positioned facing the main body portion, and the plate thickness of the terminal connection portion being smaller than the plate thickness of the electrode body connection portion.

[0007] According to the energy storage element of the present invention, it is possible to achieve a high capacity.

[0008] 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 of an energy storage element according to an embodiment, with a container body separated from the container. FIG. 3 is an exploded perspective view showing components of an energy storage element according to an embodiment, other than the container body, disassembled. FIG. 4 is a top view and a cross-sectional view showing the configuration of a first current collector according to an embodiment. FIG. 5 is a top view and a cross-sectional view showing the configuration of a second current collector according to an embodiment. FIG. 6 is a perspective view showing the configuration of a first current collector and a second current collector and their surroundings according to an embodiment. FIG. 7 is a cross-sectional view showing the configuration of a first current collector and their surroundings according to an embodiment. FIG. 8 is a plan view showing an example of an energy storage device according to an embodiment. FIG. 9 is a perspective view showing the configuration of a first current collector according to a first modification of the embodiment. FIG. 10 is a cross-sectional view showing the configuration of a first current collector according to a second modification of the embodiment.

[0009] (1) An energy storage element according to one aspect of the present invention comprises a terminal, an electrode body, and a current collector connected to the terminal and the electrode body, the current collector comprising a plate-shaped terminal connection portion connected to the terminal and a plate-shaped electrode body connection portion connected to the electrode body, the electrode body comprising a main body portion and a connection portion connected to the electrode body connection portion, the electrode body connection portion being positioned facing the main body portion, and the plate thickness of the terminal connection portion being smaller than the plate thickness of the electrode body connection portion.

[0010] In an energy storage element according to one aspect of the present invention, the current collector includes a plate-shaped terminal connection portion connected to the terminal and a plate-shaped electrode assembly connection portion connected to the electrode assembly, the electrode assembly connection portion being oriented so as to face the main body portion of the electrode assembly, and the plate thickness of the terminal connection portion being smaller than the plate thickness of the electrode assembly connection portion. By arranging the electrode assembly connection portion so as to face the main body portion of the electrode assembly, space can be saved in the plate thickness direction of the electrode assembly connection portion. Furthermore, by reducing the plate thickness of the terminal connection portion, space can also be saved in the plate thickness direction of the terminal connection portion. This allows the size of the electrode assembly in the energy storage element to be increased, thereby achieving higher capacity.

[0011] (2) In the energy storage element described in (1) above, the terminal connection portion and the electrode body connection portion may be arranged in positions facing in different directions.

[0012] According to the energy storage element described in (2) above, the terminal connection portion of the current collector and the electrode body connection portion face in different directions, thereby making it possible to save space in the different directions.

[0013] (3) In the energy storage element described in (1) or (2) above, the plate thickness of the terminal connection portion may be half or less of the plate thickness of the electrode body connection portion.

[0014] According to the energy storage element described above in (3), the thickness of the terminal connection portion of the current collector is less than half the thickness of the electrode body connection portion, thereby further reducing space in the thickness direction of the terminal connection portion.

[0015] (4) In the energy storage element described in any one of (1) to (3) above, the cross-sectional area of ​​the terminal connection portion in a plane perpendicular to the direction in which the current flows may be smaller than the cross-sectional area of ​​the electrode body connection portion in a plane perpendicular to the direction in which the current flows.

[0016] According to the energy storage element described in (4) above, the cross-sectional area of ​​the terminal connection portion of the current collector is smaller than the cross-sectional area of ​​the electrode assembly connection portion, thereby making it possible to save space around the terminal connection portion.

[0017] (5) In the energy storage device according to any one of (1) to (4) above, the terminal connection portion may have a hardness greater than that of the electrode body connection portion.

[0018] According to the energy storage element described in (5) above, the hardness of the terminal connection portion of the current collector is greater than the hardness of the electrode body connection portion, so that deformation of the terminal connection portion can be suppressed when connecting the terminal connection portion to the terminal.

[0019] Hereinafter, with reference to the drawings, an energy storage element according to an embodiment of the present invention (including its modified examples) will be described. The embodiments described below are all 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 only and are not intended to limit the present invention. In each drawing, dimensions and the like are not strictly illustrated. In each drawing, the same or similar components are designated by the same reference numerals.

[0020] 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.

[0021] In the following description, the positive X-axis direction refers to the direction of the arrow on the X-axis, 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 direction and the Z-axis direction. Expressions indicating relative directions or attitudes, such as parallel and orthogonal, also include cases where the directions or attitudes are not strictly those. When two directions are parallel (or orthogonal), it does not only mean that the two directions are completely parallel (or orthogonal), but also means that the directions are substantially parallel (or orthogonal), that is, there is a difference of about a few percent. In the following description, when the term "insulation" is used, it means "electrical insulation". An insulating material has a volume resistivity of 1×10 １０ It is preferable that the material be made of a material with a resistance of Ωm or more.

[0022] (Embodiment) [1. Description of the Configuration of Energy Storage Element 10] First, the configuration of the energy storage element 10 according to the present embodiment will be described in detail with reference to Figs. 1 to 3. Fig. 1 is a perspective view showing the appearance of the energy storage element 10 according to the present embodiment. Fig. 2 is a perspective view showing the internal configuration of the container 100 of the energy storage element 10 according to the present embodiment, with the container body 110 separated from the container 100. Fig. 3 is an exploded perspective view showing the components of the energy storage element 10 according to the present embodiment, other than the container body 110.

[0023] 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.

[0024] 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.

[0025] 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 3 , the energy storage element 10 further includes a pair of (positive and negative) lower gaskets 320, an electrode assembly 400, and a pair of (positive and negative) current collectors 500, all of which are 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 types 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.

[0026] [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.

[0027] 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.

[0028] 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 may be a weldable (joinable) metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet, or a resin. 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.

[0029] [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 Z-axis direction from the outer surface (the surface facing the positive Z-axis direction) 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.

[0030] 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).

[0031] 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.

[0032] [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. The electrode assembly 400 is a wound 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. In this embodiment, it 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 in 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.

[0033] 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.

[0034] 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.

[0035] The positive electrode plate has multiple tabs (positive electrode tabs) protruding to one side in the X-axis direction, and by winding the positive electrode plate, a positive electrode tab portion is formed in which the multiple tabs (positive electrode tabs) overlap. The negative electrode plate has multiple tabs (negative electrode tabs) protruding to the other side in the X-axis direction, and by winding the negative electrode plate, a negative electrode tab portion is formed in which the multiple tabs (negative electrode tabs) overlap. As a result, the electrode body 400 is configured to include an electrode body main body 410, a first tab portion 420 protruding from the electrode body main body 410 in the positive direction of the X-axis, and a second tab portion 430 protruding from the electrode body main body 410 in the negative direction of the X-axis. The electrode body main body 410 is the main body of the electrode body 400 and is an elongated cylindrical portion formed by winding the portions of the positive electrode plate and the negative electrode plate other than the tabs and a separator. The first tab portion 420 and the second tab portion 430 are portions that extend (protrude) outward from a part of the X-axis direction edge of the electrode body main body portion 410. In this embodiment, the first tab portion 420 is a tab portion for the positive electrode, and the second tab portion 430 is a tab portion for the negative electrode.

[0036] In this embodiment, the energy storage device 10 includes two electrode bodies 400 (electrode body 401 and electrode body 402). Both electrode bodies 401 and 402 are wound electrode bodies formed by winding a positive electrode plate, a negative electrode plate, and a separator. Therefore, the electrode body 401 includes an electrode body main body 411, a first tab portion 421 protruding from the electrode body main body 411 in the positive direction of the X-axis, and a second tab portion 431 protruding from the electrode body main body 411 in the negative direction of the X-axis. Similarly, the electrode body 402 includes an electrode body main body 412, a first tab portion 422 protruding from the electrode body main body 412 in the positive direction of the X-axis, and a second tab portion 432 protruding from the electrode body main body 412 in the negative direction of the X-axis. The first tab portions 421 and 422 are positive electrode tab portions, and the second tab portions 431 and 432 are negative electrode tab portions. The first tab portion 420 (421 and 422) is an example of a connection portion that is connected (joined) to a first electrode assembly connection portion 512 of a first current collector 510 described below. The second tab portion 430 (431 and 432) is an example of a connection portion that is connected (joined) to a second electrode assembly connection portion 522 of a second current collector 520 described below.

[0037] [1.4 Description of the Current Collector 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 collector 500 has a shape in which a single plate-like member is bent, and is an L-shaped (inverted L-shaped) member when viewed in the Y-axis direction. The current collector 500 has a simple configuration and is 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 collector 500 (space saving), the capacity of the energy storage element 10 can be improved.

[0038] In this embodiment, two current collectors 500 (a positive electrode current collector 500 and a negative electrode current collector 500) are arranged side by side in the X-axis direction. Hereinafter, one of the two current collectors 500 (the current collector 500 located in the positive direction of the X-axis) will be referred to as a first current collector 510, and the other (the current collector 500 located in the negative direction of the X-axis) will be referred to as a second current collector 520. In this embodiment, the first current collector 510 is the positive electrode current collector 500 (positive electrode current collector), and the second current collector 520 is the negative electrode current collector 500 (negative electrode current collector). The first current collector 510 (positive electrode current collector) is made 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 made of copper, a copper alloy, or the like, similar to the negative electrode current collector foil of the electrode assembly 400.

[0039] 3, the first current collector 510 includes a plate-shaped first terminal connection portion 511 and a plate-shaped first electrode assembly connection portion 512. In the present embodiment, the first current collector 510 is an integrally molded product formed from a single plate-shaped member, and the first terminal connection portion 511 and the first electrode assembly connection portion 512 are integrally formed.

[0040] The first terminal connection portion 511 is a flat, rectangular portion parallel to the XY plane and is connected (joined) to the terminal 200 (first terminal 210). The first terminal connection portion 511 is arranged along the lid 120 and has a through-hole 501 through which a shaft portion 201 of the first terminal 210 passes. The shaft portion 201 is a rivet portion of the first terminal 210 that extends in the negative Z-axis direction. The shaft portion 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 first terminal connection portion 511, and is crimped (see FIG. 7 ). As a result, the first current collector 510 and the first terminal 210 are fixed to the lid 120. The method of connecting (joining) the first current collector 510 and the first terminal 210 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.

[0041] The first electrode assembly connection portion 512 is a flat, rectangular portion parallel to the YZ plane, and is connected (joined) to the electrode assembly 400. The first electrode assembly connection portion 512 extends in the negative Z-axis direction from the end of the first terminal connection portion 511 in the positive X-axis direction along the short side wall portion 111 of the container body 110 in the positive X-axis direction. As a result, the first terminal connection portion 511 and the first electrode assembly connection portion 512 are arranged in orientations facing different directions, and the first electrode assembly connection portion 512 is arranged in an orientation facing the electrode assembly main portions 411 and 412. The first electrode assembly connection portion 512 is connected (joined) to the first tab portion 420 of the electrode assembly 400. Specifically, the first electrode assembly connection portion 512 is connected (joined) to the first tab portion 421 of the electrode assembly 401 and the first tab portion 422 of the electrode assembly 402. The first electrode body connection portion 512 and the first tab portion 420 (421 and 422) are connected (joined) by welding such as ultrasonic welding, laser welding, or resistance welding, or by mechanical joining such as crimping or screw joining.

[0042] Specifically, the first tab portion 420 is bent toward the first current collector 510, disposed on the outside of the first current collector 510, and joined to the first current collector 510. The first tab portion 421 is bent in the positive Y-axis direction toward the first electrode assembly connection portion 512, disposed in the positive X-axis direction of the first electrode assembly connection portion 512, and joined to the first electrode assembly connection portion 512. The first tab portion 422 is bent in the negative Y-axis direction toward the first electrode assembly connection portion 512, disposed in the positive X-axis direction of the first electrode assembly connection portion 512, and joined to the first electrode assembly connection portion 512. In this way, the first tab portions 420 (421 and 422) are joined to the outside of the first current collector 510 (first electrode assembly connection portion 512) while wrapping around both sides of the first current collector 510 (first electrode assembly connection portion 512) in the Y-axis direction.

[0043] Similar to the first current collector 510, the second current collector 520 includes a plate-shaped second terminal connection portion 521 and a plate-shaped second electrode assembly connection portion 522. In the present embodiment, similar to the first current collector 510, the second current collector 520 is an integrally molded product formed from a single plate-shaped member, and the second terminal connection portion 521 and the second electrode assembly connection portion 522 are integrally formed.

[0044] The second terminal connection portion 521 is a flat, rectangular portion parallel to the XY plane, and is connected (joined) to the terminal 200 (second terminal 220). The second terminal connection portion 521 is arranged along the lid 120, and has a through-hole 501 through which the shaft portion 201 of the second terminal 220 passes. The configuration in which the second terminal connection portion 521 is joined to the second terminal 220 is similar to the configuration in which the first terminal connection portion 511 is joined to the first terminal 210, and therefore a detailed description thereof will be omitted.

[0045] The second electrode assembly connection portion 522 is a flat, rectangular portion parallel to the YZ plane, and is connected (joined) to the electrode assembly 400. The second electrode assembly connection portion 522 extends in the negative Z-axis direction from the end of the second terminal connection portion 521 in the negative X-axis direction along the short side wall portion 111 of the container body 110 in the negative X-axis direction. As a result, the second terminal connection portion 521 and the second electrode assembly connection portion 522 are arranged in orientations facing different directions, and the second electrode assembly connection portion 522 is arranged in an orientation facing the electrode assembly main portions 411 and 412. The second electrode assembly connection portion 522 is connected (joined) to the second tab portion 430 of the electrode assembly 400. Specifically, the second electrode assembly connection portion 522 is connected (joined) to the second tab portion 431 of the electrode assembly 401 and the second tab portion 432 of the electrode assembly 402. The configuration in which the second electrode body connection portion 522 and the second tab portion 430 (431 and 432) are joined is similar to the configuration in which the first electrode body connection portion 512 and the first tab portion 420 (421 and 422) are joined, so detailed explanation will be omitted.

[0046] Specifically, the second tab portion 430 is bent toward the second current collector 520, disposed on the outside of the second current collector 520, and joined to the second current collector 520. The second tab portion 431 is bent in the positive Y-axis direction toward the second electrode assembly connection portion 522, disposed in the negative X-axis direction of the second electrode assembly connection portion 522, and joined to the second electrode assembly connection portion 522. The second tab portion 432 is bent in the negative Y-axis direction toward the second electrode assembly connection portion 522, disposed in the negative X-axis direction of the second electrode assembly connection portion 522, and joined to the second electrode assembly connection portion 522. In this way, the second tab portions 430 (431 and 432) are joined to the outside of the second current collector 520 (second electrode assembly connection portion 522) while wrapping around both sides of the second current collector 520 (second electrode assembly connection portion 522) in the Y-axis direction.

[0047] [2 Detailed Description of Current Collector 500] Next, the configuration of the current collector 500 (first current collector 510 and second current collector 520) will be described in more detail with reference to FIGS. 4 to 7. FIG. 4 is a top view and a cross-sectional view showing the configuration of the first current collector 510 according to this embodiment. FIG. 4(a) is a top view showing the configuration of the first current collector 510 shown in FIG. 3 when viewed from the positive direction of the Z axis. FIG. 4(b) is a cross-sectional view showing a cross section of the first current collector 510 shown in FIG. 4(a) taken along a plane parallel to the XZ plane including line IVb-IVb. FIG. 5 is a top view and a cross-sectional view showing the configuration of the second current collector 520 according to this embodiment. FIG. 5(a) is a top view showing the configuration of the second current collector 520 shown in FIG. 3 when viewed from the positive direction of the Z axis. FIG. 5B is a cross-sectional view showing a cross section of the second current collector 520 of FIG. 5A taken along a plane parallel to the XZ plane including the line Vb-Vb.

[0048] FIG. 6 is a perspective view showing the first current collector 510 and the second current collector 520 and their surrounding configuration according to this embodiment. FIG. 6 shows a configuration in which the first current collector 510 and the second current collector 520 are fixed to the lid 120 together with the first terminal 210 and the second terminal 220. FIG. 7 is a cross-sectional view showing the first current collector 510 and its surrounding configuration according to this embodiment. FIG. 7 is a cross-sectional view showing a cross section of the first current collector 510 and its surrounding configuration shown in FIG. 6 taken along a plane parallel to the XZ plane including line VII-VII. The first current collector 510 and its surrounding configuration and the second current collector 520 and its surrounding configuration have similar configurations, and therefore a cross-sectional view of the second current collector 520 and its surrounding configuration is omitted.

[0049] As shown in FIG. 4 , in addition to the through hole 501 described above, a recess 502 is formed in the first terminal connection portion 511 of the first current collector 510. The through hole 501 is a circular through hole that penetrates the first terminal connection portion 511 in the Z-axis direction and is viewed from the Z-axis direction. The recess 502 is arranged to surround the periphery of the through hole 501 and is an annular recess as viewed from the Z-axis direction, with the surface of the first terminal connection portion 511 facing the negative Z-axis direction recessed toward the positive Z-axis direction. As shown in FIG. 7 , the recess 502 is a recess in which the crimped portion is located when the shaft portion 201 of the first terminal 210 is inserted into the through hole 501 and crimped. The recess 502 is a joint portion of the first terminal connection portion 511 with the first terminal 210.

[0050] As described above, by forming the recess 502 in the first terminal connection portion 511, the portion of the first terminal connection portion 511 where the recess 502 is located (the joint portion with the first terminal 210) has a smaller thickness (thickness in the Z-axis direction) than the other portions (portions other than the joint portion with the first terminal 210). As shown in FIG. 4 , the thickness (thickness in the Z-axis direction) of the portion of the first terminal connection portion 511 other than the recess 502 (portions other than the joint portion with the first terminal 210) is referred to as the thickness T1. The thickness T1 is the maximum value of the thickness of the first terminal connection portion 511. When the thickness of the portion of the first terminal connection portion 511 other than the joint portion with the first terminal 210 varies, the maximum value of the thickness of the portion other than the joint portion is referred to as the thickness T1.

[0051] In the first electrode body connecting portion 512, by being joined to the electrode body 400, the plate thickness (thickness in the X-axis direction) may differ between the joint with the electrode body 400 and a portion other than the joint with the electrode body 400. For this reason, the plate thickness (thickness in the X-axis direction) of the portion of the first electrode body connecting portion 512 other than the joint with the electrode body 400 is referred to as plate thickness T2. When the plate thickness of the portion of the first electrode body connecting portion 512 other than the joint with the electrode body 400 varies, the average plate thickness of the portion other than the joint is taken as plate thickness T2.

[0052] In this configuration, the plate thickness T1 of the first terminal connection portion 511 is smaller than the plate thickness T2 of the first electrode assembly connection portion 512. The plate thickness T1 (maximum value if the plate thickness varies) of the portion of the first terminal connection portion 511 other than the joint with the first terminal 210 is smaller than the plate thickness T2 (average value if the plate thickness varies) of the portion of the first electrode assembly connection portion 512 other than the joint with the electrode assembly 400. The plate thickness T1 of the first terminal connection portion 511 is preferably 80% or less of the plate thickness T2 of the first electrode assembly connection portion 512, more preferably half or less (50% or less) of the plate thickness T2 of the first electrode assembly connection portion 512, and even more preferably 40% or less of the plate thickness T2 of the first electrode assembly connection portion 512. The thickness T1 of the first terminal connection portion 511 is preferably 10% or more of the thickness T2 of the first electrode body connection portion 512, more preferably 20% or more, and even more preferably 30% or more.

[0053] The thickness T1 of the first terminal connection portion 511 is preferably smaller than 2.5 mm, more preferably 2.2 mm or less, and even more preferably 2 mm or less. The thickness T2 of the first electrode body connection portion 512 is preferably 2.5 mm or more, preferably 3 mm or more, and even more preferably 4 mm or more. The thicknesses T1 of the first terminal connection portion 511 and T2 of the first electrode body connection portion 512 are measured using a vernier caliper.

[0054] The cross-sectional area of ​​the cut surface when the first terminal connection portion 511 is cut along a plane parallel to the YZ plane is referred to as the cross-sectional area S1. The cross-sectional area of ​​the cut surface when the first electrode body connection portion 512 is cut along a plane parallel to the XY plane is referred to as the cross-sectional area S2. Current flows in the X-axis direction in the first terminal connection portion 511, and current flows in the Z-axis direction in the first electrode body connection portion 512. Therefore, the cross-sectional area S1 is the cross-sectional area in a plane (YZ plane) perpendicular to the direction in which current flows in the first terminal connection portion 511 (X-axis direction). The cross-sectional area S2 is the cross-sectional area in a plane (XY plane) perpendicular to the direction in which current flows in the first electrode body connection portion 512 (Z-axis direction). Specifically, the cross-sectional area S1 is the cross-sectional area (maximum value if the cross-sectional area varies) of the first terminal connection portion 511 at a portion other than the joint portion with the first terminal 210. The cross-sectional area S2 is the cross-sectional area of ​​the first electrode assembly connecting portion 512 at a portion other than the joint with the electrode assembly 400 (or the average value if the cross-sectional area varies).

[0055] In this configuration, the cross-sectional area S1 of the first terminal connection portion 511 is smaller than the cross-sectional area S2 of the first electrode body connection portion 512. The cross-sectional area S1 of the first terminal connection portion 511 in a plane perpendicular to the direction of current flow is smaller than the cross-sectional area S2 of the first electrode body connection portion 512 in a plane perpendicular to the direction of current flow. The cross-sectional area S1 of the first terminal connection portion 511 is preferably 80% or less of the cross-sectional area S2 of the first electrode body connection portion 512, more preferably half or less (50% or less), and even more preferably 40% or less. The cross-sectional area S1 of the first terminal connection portion 511 is preferably 10% or more of the cross-sectional area S2 of the first electrode body connection portion 512, more preferably 20% or more, and even more preferably 30% or more. The cross-sectional area S1 of the first terminal connection portion 511 is calculated by multiplying the plate thickness T1 of the first terminal connection portion 511 by the width in the Y-axis direction of the first terminal connection portion 511. The cross-sectional area S2 of the first electrode body connection portion 512 is calculated by multiplying the plate thickness T2 of the first electrode body connection portion 512 by the width in the Y-axis direction of the first electrode body connection portion 512. In the present embodiment, the width in the Y-axis direction of the first terminal connection portion 511 and the width in the Y-axis direction of the first electrode body connection portion 512 are the same, but may be different.

[0056] The hardness of the first terminal connection portion 511 is greater than the hardness of the first electrode assembly connection portion 512. Specifically, the hardness (maximum value if the hardness varies) of the portion of the first terminal connection portion 511 other than the joint with the first terminal 210 is greater than the hardness (average value if the hardness varies) of the portion of the first electrode assembly connection portion 512 other than the joint with the electrode assembly 400. In this embodiment, the hardness of the first terminal connection portion 511 is made greater than the hardness of the first electrode assembly connection portion 512 by pressing the first terminal connection portion 511 with a greater force than the first electrode assembly connection portion 512 (such as by applying a forging press process). By pressing the first terminal connection portion 511 with a greater force than the first electrode assembly connection portion 512, the first terminal connection portion 511 is made thinner and harder than the first electrode assembly connection portion 512. The hardness comparison is performed in accordance with JIS Z2243 to JIS Z2246.

[0057] 5 , a recess 502 is also formed in the second terminal connection portion 521 of the second current collector 520, similar to the first terminal connection portion 511. The recess 502 of the second terminal connection portion 521 has a configuration similar to the recess 502 of the first terminal connection portion 511, and therefore a detailed description thereof will be omitted. In this configuration, similar to the first current collector 510, the plate thickness T3 of the second terminal connection portion 521 is smaller than the plate thickness T4 of the second electrode assembly connection portion 522. The definition of the plate thickness T3 of the second terminal connection portion 521 is the same as the definition of the plate thickness T1 of the first terminal connection portion 511, and the definition of the plate thickness T4 of the second electrode assembly connection portion 522 is the same as the definition of the plate thickness T2 of the first electrode assembly connection portion 512.

[0058] As described above, the first current collector 510 (positive electrode current collector) is made of aluminum, an aluminum alloy, or the like, and the second current collector 520 (negative electrode current collector) is made of copper, a copper alloy, or the like. As a result, the second current collector 520 has higher electrical conductivity and thermal conductivity than the first current collector 510, so the second electrode assembly connection portion 522 can be made thinner than the first electrode assembly connection portion 512. For this reason, the plate thickness T3 of the second terminal connection portion 521 can be made as small as the plate thickness T1 of the first terminal connection portion 511, and the plate thickness T4 of the second electrode assembly connection portion 522 can be made smaller than the plate thickness T2 of the first electrode assembly connection portion 512. The ratio (T4 / T3) of the plate thickness T4 of the second electrode body connection portion 522 to the plate thickness T3 of the second terminal connection portion 521 is smaller than the ratio (T2 / T1) of the plate thickness T2 of the first electrode body connection portion 512 to the plate thickness T1 of the first terminal connection portion 511.

[0059] Specifically, the plate thickness T3 of the second terminal connection portion 521 is preferably 90% or less, more preferably 85% or less, and even more preferably 80% or less of the plate thickness T4 of the second electrode body connection portion 522. The plate thickness T3 of the second terminal connection portion 521 is preferably 20% or more, more preferably 40% or more, and even more preferably 60% or more of the plate thickness T4 of the second electrode body connection portion 522. The plate thickness T3 of the second terminal connection portion 521 is preferably 2.2 mm or less, more preferably 2.1 mm or less, and even more preferably 2 mm or less. The plate thickness T4 of the second electrode body connection portion 522 is preferably 2.3 mm or more, preferably 2.4 mm or more, and even more preferably 2.5 mm or more.

[0060] Similar to the first current collector 510, the cross-sectional area S3 of the second terminal connection portion 521 in a plane perpendicular to the direction of current flow is smaller than the cross-sectional area S4 of the second electrode assembly connection portion 522 in a plane perpendicular to the direction of current flow. The definitions of the cross-sectional area S3 of the second terminal connection portion 521 are the same as the definitions of the cross-sectional area S1 of the first terminal connection portion 511, and the definitions of the cross-sectional area S4 of the second electrode assembly connection portion 522 are the same as the definitions of the cross-sectional area S2 of the first electrode assembly connection portion 512. The ratio (S4 / S3) of the cross-sectional area S4 of the second electrode assembly connection portion 522 to the cross-sectional area S3 of the second terminal connection portion 521 is smaller than the ratio (S2 / S1) of the cross-sectional area S2 of the first electrode assembly connection portion 512 to the cross-sectional area S1 of the first terminal connection portion 511. The cross-sectional area S3 of the second terminal connection portion 521 is preferably 90% or less, more preferably 85% or less, and even more preferably 80% or less of the cross-sectional area S4 of the second electrode body connection portion 522. The cross-sectional area S3 of the second terminal connection portion 521 is preferably 20% or more, more preferably 40% or more, and even more preferably 60% or more of the cross-sectional area S4 of the second electrode body connection portion 522.

[0061] Similar to the first current collector 510, the hardness of the second terminal connection portion 521 is greater than the hardness of the second electrode body connection portion 522. The definition of the hardness of the second terminal connection portion 521 is the same as the definition of the hardness of the first terminal connection portion 511, and the definition of the hardness of the second electrode body connection portion 522 is the same as the definition of the hardness of the first electrode body connection portion 512.

[0062] [3 Description of Effects] As described above, according to the energy storage element 10 according to the embodiment of the present invention, the first current collector 510 includes a plate-shaped first terminal connection portion 511 connected to the first terminal 210 and a plate-shaped first electrode assembly connection portion 512 connected to the electrode assembly 400. The first electrode assembly connection portion 512 is disposed facing the electrode assembly main body portion 410 of the electrode assembly 400, and the plate thickness T1 of the first terminal connection portion 511 is smaller than the plate thickness T2 of the first electrode assembly connection portion 512. By disposing the first electrode assembly connection portion 512 facing the electrode assembly main body portion 410 of the electrode assembly 400 in this manner, it is possible to reduce space in the plate thickness direction (X-axis direction) of the first electrode assembly connection portion 512. By reducing the plate thickness T1 of the first terminal connection portion 511, it is also possible to reduce space in the plate thickness direction (Z-axis direction) of the first terminal connection portion 511. The same applies to the second current collector 520. This allows the size of the electrode body 400 in the energy storage device 10 to be increased, thereby achieving a higher capacity.

[0063] Specifically, in order to increase the size of the electrode assembly 400 and thereby increase the capacity, the first electrode assembly connecting portion 512 is disposed in a position facing the electrode assembly main body portion 410 of the electrode assembly 400. In this configuration, by making the plate thickness T2 of the first electrode assembly connecting portion 512 relatively large, heat generation when current is passed through the first current collector 510 can be suppressed. In other words, even if the plate thickness T2 of the first electrode assembly connecting portion 512 is made relatively large to suppress heat generation when current is passed through the first current collector 510, by disposing the first electrode assembly connecting portion 512 in a position facing the electrode assembly main body portion 410 of the electrode assembly 400, space can be saved in the plate thickness direction of the first electrode assembly connecting portion 512. This allows the size of the electrode assembly 400 to be increased in the plate thickness direction of the first electrode assembly connecting portion 512, thereby achieving high capacity. In particular, in a configuration in which the first electrode body connection portion 512 is larger (longer) than the first terminal connection portion 511, as in the present embodiment, increasing the plate thickness T2 of the first electrode body connection portion 512 can improve heat dissipation, thereby allowing the plate thickness T1 of the first terminal connection portion 511 to be reduced. Reducing the plate thickness T1 of the first terminal connection portion 511 allows the length of the electrode body 400 in the height direction (Z-axis direction) to be increased, thereby enabling higher capacity. In the case of an electrode body 400 that is horizontally long (long in the X-axis direction) as in the present embodiment, reducing the plate thickness T1 of the first terminal connection portion 511 has a large contribution to increasing capacity. The same is true for the second current collector 520.

[0064] By having the first terminal connection portion 511 and the first electrode assembly connection portion 512 of the first current collector 510 facing in different directions (the Z-axis direction and the X-axis direction), it is possible to save space in the different directions.

[0065] Since the plate thickness T1 of the first terminal connection portion 511 of the first current collector 510 is less than half the plate thickness T2 of the first electrode body connection portion 512, further space saving in the plate thickness direction of the first terminal connection portion 511 can be achieved.

[0066] In the first current collector 510, the cross-sectional area S1 of the first terminal connection portion 511 is smaller than the cross-sectional area S2 of the first electrode body connection portion 512, thereby making it possible to save space around the first terminal connection portion 511. The same applies to the second current collector 520.

[0067] In the first current collector 510, the hardness of the first terminal connection portion 511 is greater than the hardness of the first electrode body connection portion 512, so that deformation of the first terminal connection portion 511 can be suppressed when connecting the first terminal connection portion 511 to the first terminal 210. This is particularly effective when the first terminal connection portion 511 and the first terminal 210 are connected by crimping or the like, as in the present embodiment, because the first terminal connection portion 511 is easily deformed. The same applies to the second current collector 520.

[0068] In the first current collector 510, the first terminal connection portion 511 and the first electrode body connection portion 512 are integrally formed, which reduces the number of parts compared to when the first terminal connection portion 511 and the first electrode body connection portion 512 are formed separately. In this case, by applying a forging press process or the like to the portion of the first terminal connection portion 511 of the integral plate-like member that constitutes the first current collector 510, the plate thickness of the first terminal connection portion 511 can be made smaller and the hardness greater than that of the first electrode body connection portion 512. The same applies to the second current collector 520.

[0069] The energy storage element 10 in 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. 8 is a plan view showing an example of an energy storage device 12 according to the present embodiment. As shown in FIG. 8, a plurality of energy storage units 11 are arranged inside the energy storage device 12. The energy storage unit 11 is composed of a plurality of electrically connected energy storage elements 10. The energy storage device 12 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 11, and the like. The energy storage unit 11 or the energy storage device 12 may include a status monitoring device (not shown) that monitors the status of one or more energy storage elements 10. The energy storage device 12 may include only one energy storage unit 11. The energy storage unit 11 may also be referred to as an energy storage device.

[0070] [4 Description of Modifications] While the energy storage device 10 according to the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. The embodiment disclosed herein is illustrative in all respects, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

[0071] (Variation 1) In the above embodiment, the current collector 500 has a shape formed by bending a single plate-like member, but this is not limited to this. In the first current collector 510, the first terminal connection portion 511 may be a plate-like portion, and its shape is not particularly limited. The first electrode body connection portion 512 may be a plate-like portion that is arranged in an orientation facing the electrode body main body portion 410, and its shape is not particularly limited. The same applies to the second current collector 520. An example will be described below. Figure 9 is a perspective view showing the configuration of a first current collector 530 according to Variation 1 of this embodiment.

[0072] As shown in FIG. 9 , the first current collector 530 in this modification includes a first terminal connection portion 531 and a first electrode assembly connection portion 532. The first terminal connection portion 531 has a configuration similar to that of the first terminal connection portion 511 in the above embodiment. The first electrode assembly connection portion 532 is a plate-shaped portion (comb-like portion) in which slits 532 a are formed in the first electrode assembly connection portion 512 in the above embodiment. In this modification, the first electrode assembly connection portion 532 is formed with two slits 532 a that extend in the positive Z-axis direction from its end in the negative Z-axis direction and penetrate in the X-axis direction. The first tab portions 421 and 422 are inserted into and joined to these two slits 532 a.

[0073] In this configuration, the plate thickness T5 of the first terminal connection portion 531 is smaller than the plate thickness T6 of the first electrode body connection portion 532. The plate thickness T5 in this modified example is the same as the plate thickness T1 in the above embodiment, and the plate thickness T6 in this modified example is the same as the plate thickness T2 in the above embodiment. The cross-sectional area S5 in a plane perpendicular to the direction of current flow in the first terminal connection portion 531 is smaller than the cross-sectional areas S6 and S7 in a plane perpendicular to the direction of current flow in the first electrode body connection portion 532. The cross-sectional area S5 in this modified example is the same as the cross-sectional area S1 in the above embodiment, and the cross-sectional area S6 in this modified example is the same as the cross-sectional area S2 in the above embodiment. The cross-sectional area S7 in this modified example is the sum of the cross-sectional areas of the cross sections when the portion of the first electrode body connection portion 532 where the slit 532a is formed is cut along a plane parallel to the XY plane. Thus, the cross-sectional area S5 of the first terminal connection portion 531 is smaller than the cross-sectional area S7, which is the sum of the cross-sectional areas of the portions where the slits 532a are formed in the first electrode body connection portion 532. Furthermore, the hardness of the first terminal connection portion 531 is greater than the hardness of the first electrode body connection portion 532.

[0074] Other configurations of this modified example are the same as those of the above-described embodiment, and therefore description thereof will be omitted. This modified example also achieves the same effects as those of the above-described embodiment. The same applies to the second current collector 520. In this way, current collectors 500 of various shapes can be applied.

[0075] (Variation 2) In the above embodiment, the first terminal connection portion 511 and the first electrode assembly connection portion 512 of the first current collector 510 are integrally formed, but this is not limited thereto. The first terminal connection portion 511 and the first electrode assembly connection portion 512 may be formed as separate bodies and joined to each other by a joining method such as welding. The same applies to the second current collector 520. An example of this is described below. Fig. 10 is a cross-sectional view showing the configuration of a first current collector 540 according to Variation 2 of this embodiment. Fig. 10 is a view corresponding to Fig. 4(b).

[0076] As shown in FIG. 10 , the first current collector 540 in this modified example includes a first member 541 and a second member 542. The first member 541 includes a first terminal connection portion 541a and a current collector connection portion 541b. The first terminal connection portion 541a is a flat, rectangular portion parallel to the XY plane, and the current collector connection portion 541b is a flat, rectangular portion parallel to the YZ plane. The first member 541 has a bent plate-like shape and is L-shaped (inverted L-shaped) when viewed from the Y-axis direction. The first terminal connection portion 541a has the same configuration as the first terminal connection portion 511 in the above embodiment. The second member 542 is a flat, rectangular portion parallel to the YZ plane and has the same configuration as the first electrode assembly connection portion 512 in the above embodiment. For this reason, hereinafter, the second member 542 will also be referred to as the first electrode assembly connection portion 542.

[0077] The first member 541 and the second member 542 are formed as separate bodies and joined by welding. Specifically, the current collector connection portion 541b of the first member 541 and the second member 542 (first electrode body connection portion 542) are stacked in the X-axis direction and joined in the X-axis direction. The current collector connection portion 541b and the second member 542 (first electrode body connection portion 542) may be joined by a method other than welding, such as adhesive bonding, fitting, or crimping. In this manner, in this modified example, the first terminal connection portion 541a and the first electrode body connection portion 542 are formed as separate bodies and joined to each other by a joining method such as welding.

[0078] In this configuration, the plate thickness T7 of the first terminal connection portion 541a is smaller than the plate thickness T8 of the first electrode body connection portion 542. The plate thickness T7 in this modified example is the same as the plate thickness T1 in the above embodiment, and the plate thickness T8 in this modified example is the same as the plate thickness T2 in the above embodiment. The cross-sectional area S8 of the first terminal connection portion 541a in a plane perpendicular to the direction of current flow is smaller than the cross-sectional area S9 of the first electrode body connection portion 542 in a plane perpendicular to the direction of current flow. The cross-sectional area S8 in this modified example is the same as the cross-sectional area S1 in the above embodiment, and the cross-sectional area S9 in this modified example is the same as the cross-sectional area S2 in the above embodiment. In this modified example, the hardness of the first terminal connection portion 541a is the same as the hardness of the first electrode body connection portion 542, but may be greater or less than the hardness of the first electrode body connection portion 542.

[0079] The remaining configuration of this modified example is the same as that of the above-described embodiment, and therefore description thereof will be omitted. This modified example can also achieve the same effects as those of the above-described embodiment. In this modified example, the first member 541 does not have the current collector connection portion 541b, and the second member 542 may have a portion parallel to the XY plane, and this portion may be joined to the first member 541 (first terminal connection portion 541a). The various matters described above can also be applied to the second current collector 520. In this way, current collectors 500 of various shapes can be used.

[0080] (Other Modifications) In the above embodiment, the electrode body 400 includes the first tab portion 420 (421, 422), and the first tab portion 420 is connected (joined) to the first current collector 510. However, the electrode body 400 does not have to include the first tab portion 420. The end portion of the electrode body 400 in the positive direction of the X-axis (the portion that protrudes in the positive direction of the X-axis from the entire edge of the electrode body main body portion 410) may be connected (joined) to the first current collector 510. In this case, this end portion of the electrode body 400 is an example of a connection portion that is connected (joined) to the first electrode body connection portion 512 of the first current collector 510. The same applies to the second tab portion 430 (431, 432).

[0081] In the above embodiment, the first tab portions 420 (421, 422) are positioned and joined to the outside (positive direction of the X-axis) of the first current collector 510 (first electrode body connection portion 512), but may be positioned and joined to the inside (negative direction of the X-axis). Similarly, the second tab portions 430 (431, 432) are positioned and joined to the outside (negative direction of the X-axis) of the second current collector 520 (second electrode body connection portion 522), but may be positioned and joined to the inside (positive direction of the X-axis).

[0082] In the above embodiment, the recess 502 is formed in the first terminal connection portion 511 of the first current collector 510, but the recess 502 may not be formed. Depending on the connection configuration between the first terminal connection portion 511 and the first terminal 210, the through hole 501 may not be formed in the first terminal connection portion 511. The same applies to the second terminal connection portion 521 of the second current collector 520.

[0083] In the above embodiment, the first terminal connection portion 511 and the first electrode assembly connection portion 512 of the first current collector 510 are arranged in positions facing in different directions, but they may also be arranged in positions facing in the same direction. The same applies to the second current collector 520.

[0084] In the above embodiment, in the first current collector 510, the cross-sectional area S1 in a plane perpendicular to the direction of current flow in the first terminal connection portion 511 is smaller than the cross-sectional area S2 in a plane perpendicular to the direction of current flow in the first electrode body connection portion 512, but this is not limited to this. The cross-sectional area S1 may be the same size as the cross-sectional area S2, or may be larger than the cross-sectional area S2. The same applies to the second current collector 520.

[0085] In the above embodiment, the hardness of the first terminal connection portion 511 of the first current collector 510 is greater than the hardness of the first electrode body connection portion 512, but this is not limited to this. The hardness of the first terminal connection portion 511 may be the same as the hardness of the first electrode body connection portion 512, or may be less than the hardness of the first electrode body connection portion 512. The same applies to the second current collector 520.

[0086] In the above embodiment, the electrode body 400 (401, 402) is a wound electrode body whose winding axis is parallel to the lid body 120. However, the electrode body 400 may also be a wound electrode body whose winding axis is perpendicular to the lid body 120. The electrode body 400 may be a laminated (stacked) electrode body formed by stacking a plurality of flat electrode plates, or may be a bellows-type electrode body in which electrode plates are folded in a bellows shape, or may be an electrode body of another form.

[0087] In the above embodiment, the energy storage element 10 is provided with two electrode bodies 400 (401, 402), but the number of electrode bodies 400 is not particularly limited and may be one, or three or more.

[0088] In the above embodiment, the walls of the container 100 (the short side wall 111, the long side wall 112, etc.) are flat walls, but they may also be curved walls with at least a portion curved.

[0089] Any combination of the components included in the above-described embodiments and their modifications is also included within the scope of the present invention.

[0090] The present invention can be applied to an electric storage device such as a lithium ion secondary battery.

[0091] REFERENCE SIGNS LIST 10 Energy storage element 11 Energy storage unit 12 Energy storage device 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 410, 411, 412 Electrode body body portion 420, 421, 422 First tab portion 430, 431, 432 Second tab portion 500 Current collector 502 Recess 510, 530, 540 First current collector 511, 531, 541a First terminal connection portion 512, 532 First electrode assembly connection portion 520 Second current collector 521 Second terminal connection portion 522 Second electrode assembly connection portion 532a Slit 541 First member 541b Current collector connection portion 542 Second member (first electrode assembly connection portion)

Claims

1. An energy storage element comprising: a terminal, an electrode body, and a current collector connected to the terminal and the electrode body, wherein the current collector comprises a plate-shaped terminal connection portion connected to the terminal, and a plate-shaped electrode body connection portion connected to the electrode body, wherein the electrode body comprises a main body portion and a connection portion connected to the electrode body connection portion, wherein the electrode body connection portion is positioned facing the main body portion, and the plate thickness of the terminal connection portion is smaller than the plate thickness of the electrode body connection portion.

2. The energy storage element according to claim 1, wherein the terminal connection portion and the electrode body connection portion are arranged facing in different directions.

3. The energy storage element according to claim 1 or 2, wherein the plate thickness of the terminal connection portion is half or less of the plate thickness of the electrode body connection portion.

4. The energy storage element according to claim 1 or 2, wherein the cross-sectional area of ​​the terminal connection portion in a plane perpendicular to the direction of current flow is smaller than the cross-sectional area of ​​the electrode body connection portion in a plane perpendicular to the direction of current flow.

5. The energy storage element according to claim 1 or 2, wherein the hardness of the terminal connection portion is greater than the hardness of the electrode body connection portion.

Images