Power storage element

Abstract

To provide a power storage element with improved reliability.SOLUTION: A power storage element comprises a terminal 200, an electrode body 500, and a current collector 400, the current collector comprises a first portion 430 connected to the electrode body, a second portion 440 connected to the terminal, and a third portion 450 arranged between the first portion and the second portion, and in a cross-section perpendicular to the direction of a conductive path between the first portion and the second portion, the cross-sectional area of the third portion is greater than the cross-sectional areas of the sections before and after the third portion in the direction of the conductive path.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a secondary battery. The secondary battery includes a flat rectangular battery case, a pair of external terminals arranged outside the battery case, a wound body which is a flat wound group housed inside the battery case, and a pair of current collector plates which electrically connect the external terminals and the wound body. The current collector plates are arranged approximately parallel to the battery lid and include a base portion connected to the external terminals and a pair of connection pieces connected to electrodes which constitute the wound body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-33707 Summary of the Invention [Problem to be solved by the invention]

[0004] In the secondary battery disclosed in Patent Document 1, the connection piece of the current collector plate is formed as a plate-like piece that hangs down from the base and is joined to the connection portion of the winding body. In this configuration, the connection portion of the winding body is formed by winding and stacking the exposed foil portions of the electrode plates. Therefore, the connection piece of the current collector plate is required to avoid interference with the exposed foil portions in areas other than the joint with the connection portion. This makes it difficult to increase the cross-sectional area of ​​the connection portion. On the other hand, if a large current flows through the connection piece for a long period of time, for example, the current collector plate may heat up, which may cause malfunctions in the secondary battery.

[0005] The present invention was made by the inventors of the present application by focusing on the above-mentioned problems, and has an object to provide an energy storage element with improved reliability. [Means for solving the problem]

[0006] An energy storage element according to one embodiment of the present invention comprises a terminal, an electrode body, and a current collector, the current collector comprising a first portion connected to the electrode body, a second portion connected to the terminal, and a third portion disposed between the first portion and the second portion, and in a cross section perpendicular to the direction of a conductive path between the first portion and the second portion, the cross-sectional area of ​​the third portion is larger than the cross-sectional areas of the portions before and after the third portion in the direction of the conductive path. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an energy storage element with improved reliability. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing the appearance of an energy storage device according to an embodiment. [Figure 2] FIG. 2 is a perspective view showing the internal configuration of a container according to the embodiment. [Figure 3] FIG. 3 is an exploded perspective view showing components other than the container body of the energy storage device according to the embodiment. [Figure 4] FIG. 4 is a side view showing the configuration of the electrode body according to the embodiment. [Figure 5] FIG. 5 is a side view showing the positional relationship between the electrode body and the first connection portion according to the embodiment. [Figure 6] FIG. 6 is a perspective view showing the configuration of a current collector according to the embodiment. [Figure 7] FIG. 7 is a perspective view showing the configuration of a current collector according to the first modification of the embodiment. [Figure 8] FIG. 8 is a perspective view showing the configuration of a current collector according to the second modification of the embodiment. [Figure 9] FIG. 9 is a plan view schematically illustrating an example of a power storage device according to a third modification of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] (1) An energy storage element according to one embodiment of the present invention comprises a terminal, an electrode body, and a current collector, the current collector comprising a first portion connected to the electrode body, a second portion connected to the terminal, and a third portion disposed between the first portion and the second portion, and in a cross section perpendicular to the direction of a conductive path between the first portion and the second portion, the cross-sectional area of ​​the third portion is larger than the cross-sectional areas of the portions before and after the third portion in the direction of the conductive path.

[0010] In an energy storage device according to one aspect of the present invention, the current collector includes a third portion having a relatively large cross-sectional area between the first portion and the second portion. This reduces interference between the third portion and the electrode assembly, and the third portion improves the heat capacity of the current collector. This reduces heat generation from the current collector during charging and / or discharging. This reduces defects in the energy storage device due to heat generation from the current collector. As a result, the reliability of the energy storage device is improved.

[0011] (2) In the energy storage element described in (1) above, the current collector may have a first connection portion including the first portion and the third portion, the first connection portion being a plate-shaped portion extending in a first direction, the electrode body may have a pair of curved portions opposing each other in the first direction and an intermediate portion between the pair of curved portions, the intermediate portion having a tab portion protruding in a second direction intersecting the first direction, the first portion opposing the intermediate portion in the second direction and connected to the tab portion, and the third portion opposing one of the pair of curved portions in the second direction.

[0012] According to the energy storage element described in (2) above, the third portion having a relatively large cross-sectional area is disposed in a position facing the curved portion in the second direction, which is an area where the tab portion is not present, thereby more reliably suppressing interference between the tab portion and the third portion.

[0013] (3) In the energy storage element described in (1) or (2) above, the width of the third portion in a third direction intersecting the direction of the conductive path and the opposing direction of the current collector and the electrode body may be greater than the width of the front and rear portions in the third direction.

[0014] According to the energy storage element described in (3) above, the third portion of the current collector has a large width in the third direction, which is not the direction in which the current collector and the electrode assembly face each other, and therefore the cross-sectional area of ​​the third portion is larger than the cross-sectional areas in front of and behind it, thereby more reliably suppressing interference between the third portion and the electrode assembly.

[0015] (4) In the energy storage element described in (3) above, the third portion may have a shape that protrudes more than the front and rear portions on both sides in the third direction.

[0016] According to the energy storage element described in (4) above, even if the width of the third portion in the first direction cannot be increased, a relatively large heat dissipation area can be secured by making the third portion protrude on both sides in the third direction.

[0017] The present invention may be realized as a current collector included in the electricity storage element according to any one of (1) to (4) above.

[0018] 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, the arrangement and connection of the components, manufacturing processes, and the order of the 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 assigned the same reference numerals. Each drawing may be a schematic drawing in which emphasis, omission, or adjustment of proportions is appropriately made to illustrate the present invention.

[0019] In the following description and drawings, the X-axis direction refers to the opposing direction of a pair of short side walls of the container of the energy storage element, the juxtaposition direction of a pair of terminals (positive and negative electrodes; the same applies hereinafter) of the energy storage element, the juxtaposition direction of a pair of current collectors, the direction in which the first connection portion of the current collector faces, the thickness (plate thickness) direction of the first connection portion, the direction of the winding axis of the electrode assembly, or the longitudinal direction of the electrode assembly. The Y-axis direction refers to the thickness direction of the container (the direction in which the width is smallest; the same applies hereinafter), the opposing direction of a pair of long side walls of the container, the juxtaposition direction of two electrode assemblies, or the thickness direction of one electrode assembly. The Z-axis direction refers to the juxtaposition direction of the container body and lid of the container, the juxtaposition direction of the electrode assembly and terminals, the direction in which the second connection portion of the current collector faces, the thickness (plate thickness) direction of the second connection portion, 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 mode of use, the Z-axis direction may not be the up-down direction, but for the sake of convenience, the following description will be given assuming that the Z-axis direction is the up-down direction.

[0020] In the following explanation, the positive X-axis direction refers to the direction of the X-axis arrow, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. When simply referring to the X-axis direction, it refers to both or either of the positive X-axis direction and the negative X-axis direction. The same applies to the Y-axis and Z-axis directions. Expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the directions or attitudes are not strictly those. When two directions are parallel (or perpendicular), it does not only mean that the two directions are completely parallel (or perpendicular), but also means that the directions are substantially parallel (or perpendicular), that is, there is a difference of, for example, a few percent. In the following explanation, when the term "insulation" is used, it means "electrical insulation." The volume resistivity of an insulating material is 1×10 6 Ωm or more is preferable, and 1×10 7 Ωm or more is preferable, and 1×10 10 More preferably, it is Ωm or more.

[0021] (Embodiment) [1. Description of the configuration of energy storage element 10] First, the configuration of an energy storage device 10 according to the present embodiment will be described with reference to Figs. 1 to 3. Fig. 1 is a perspective view showing the appearance of an energy storage device 10 according to the embodiment. Fig. 2 is a perspective view showing the internal configuration of a container 100 according to the embodiment. Fig. 3 is an exploded perspective view showing components of an energy storage device 10 according to the embodiment other than a container body 110.

[0022] The energy storage device 10 is a secondary battery (single cell) that can charge and discharge electricity, and more specifically, is a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage device 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 device 10 can also be used as a stationary battery for home or business use.

[0023] 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, 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.

[0024] 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 an electrode assembly 500, a pair of (positive and negative) lower gaskets 320, and a pair of (positive and negative) current collectors 400 housed inside the container 100. An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but is not shown. The type of electrolyte is not particularly limited as long as it does not impair the performance of the energy storage element 10, and various electrolytes can be selected. In addition to the above-mentioned components, the energy storage element 10 may also include spacers disposed on the sides or below the electrode assembly 500, an insulating film wrapping the electrode assembly 500, and the like.

[0025] [1-1. Description of the container 100] As shown in FIG. 2, the container 100 is a rectangular parallelepiped (square or box-shaped) case including a container body 110 with an opening facing the positive direction of the Z axis and a lid 120. The container body 110 is a rectangular cylindrical member with a bottom that constitutes the main body of the container 100. The lid 120 is a lid that closes the opening of the container body 110 and is a flat, rectangular member extending in the X axis direction. The lid 120 is disposed in the positive direction of the Z axis of the container body 110. If the Z axis direction is defined as a first direction, the positive Z axis direction may be expressed as one side of the first direction, and the negative Z axis direction may be expressed as the other side of the first direction. In this case, the X axis direction may be expressed as a second direction intersecting with the first direction, and the Y axis direction may be expressed as a third direction intersecting with the first and second directions.

[0026] The container body 110 includes a pair of short side walls 111 forming both surfaces (short sides) in the X-axis direction, a pair of long side walls 112 forming both surfaces (long sides) in the Y-axis direction, and a bottom wall 113 on the surface (bottom) in the negative Z-axis direction (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.

[0027] After the electrode assembly 500 and the like 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 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, a gas release valve for releasing pressure inside the container 100 if the pressure inside the container 100 increases excessively, and the like.

[0028] [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 500 via the current collector 400. The terminals 200 are metal members that conduct electricity stored in the electrode assembly 500 to the external space of the energy storage element 10 and also introduce electricity into the internal space of the energy storage element 10 in order to store electricity in the electrode assembly 500.

[0029] Terminal 200 includes a terminal body disposed in the positive direction of the Z axis of lid body 120, and a shaft portion 201 extending from the terminal body in the negative direction of the Z axis and penetrating lid body 120. Terminal 200 is formed of a conductive material such as a metal, such as aluminum, aluminum alloy, copper, or copper alloy. Terminal 200 is connected (joined) to current collector 400 by crimping, welding, or the like, and is attached to lid body 120. Terminal 200 is disposed in a state protruding in the positive direction of the Z axis from the outer surface (the surface facing the positive direction of the Z axis) of lid body 120. In this embodiment, terminal 200 is a welded terminal that is welded to an external conductive member, such as a bus bar. Terminal 200 may also be a bolt terminal that includes a bolt portion formed with a male thread that protrudes in the positive direction of the Z axis and is joined to the conductive member by bolt fastening.

[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, when distinguishing between these two terminals 200, one (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 400, and provides insulation between the lid 120 and the current collector 400. 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 body 500] The electrode assembly 500 is an electricity storage element (power generating element) that can store electricity and is formed by stacking positive and negative electrode plates and separators. The electrode assembly 500 is a wound-type electrode assembly formed by winding the positive and negative electrode plates and separators around a winding axis extending in the X-axis direction. The winding axis is an imaginary axis that serves as the central axis when winding the positive and negative electrode plates, etc., and in this embodiment, it is a straight line that passes through the center of the electrode assembly 500 and is parallel to the X-axis direction. In this embodiment, the electrode assembly 500 has an elongated shape that extends in the X-axis direction and has a substantially oval cylindrical shape (an oval shape when viewed from the X-axis direction). The shape of the electrode assembly 500 is not particularly limited and may be a substantially cylindrical shape or a substantially elliptical cylindrical shape, and the length of the electrode assembly 500 in the X-axis direction is also not particularly limited. The electrode assembly 500 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 separator materials include woven fabric, nonwoven fabric, and porous resin film.

[0035] The positive electrode plate has a plurality of tabs 528 (positive electrode tabs) protruding to one side in the X-axis direction, and by winding the positive electrode plate, a positive electrode tab portion 520 is formed in which the plurality of tabs 528 (positive electrode tabs) overlap. The negative electrode plate has a plurality of tabs 528 (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 520 is formed in which the plurality of tabs 528 (negative electrode tabs) overlap. As a result, the electrode assembly 500 has a main body portion 510 and tab portions 520 protruding from the main body portion 510 on one and the other sides of the main body portion 510 in the X-axis direction. The main body portion 510 is the main body portion of the electrode assembly 500, 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 528 and the separator. In the present embodiment, when distinguishing between the pair of tab portions 520 protruding from main body portion 510, tab portion 520 protruding from main body portion 510 in the positive direction of the X-axis is referred to as first tab portion 521, and tab portion 520 protruding from main body portion 510 in the negative direction of the X-axis is referred to as second tab portion 523. In the present embodiment, first tab portion 521 is the tab portion 520 of the positive electrode, and second tab portion 523 is the tab portion 520 of the negative electrode.

[0036] In this embodiment, the energy storage element 10 includes two electrode bodies 500. The two electrode bodies 500 are aligned in the Y-axis direction as shown in FIGS. 2 and 3. As a result, the two first tab portions 521 are aligned in the Y-axis direction, and the two second tab portions 523 are aligned in the Y-axis direction. The two first tab portions 521 aligned in the Y-axis direction are connected to the positive electrode current collector 400. As a result, the two first tab portions 521 are electrically connected to the first terminal 210 via the positive electrode current collector 400. The two second tab portions 523 aligned in the Y-axis direction are connected to the negative electrode current collector 400. As a result, the two second tab portions 523 are electrically connected to the second terminal 220 via the negative electrode current collector 400. Hereinafter, when distinguishing between the two electrode bodies 500 included in the energy storage device 10, the electrode body 500 in the negative Y-axis direction will be referred to as electrode body 500A, and the electrode body 500 in the positive Y-axis direction will be referred to as electrode body 500B.

[0037] [1-4. Description of the current collector 400] The current collectors 400 are conductive current collecting members (positive electrode current collector and negative electrode current collector) disposed on both sides of the electrode assembly 500 in the X-axis direction and connected (joined) to the electrode assembly 500 and the terminal 200, electrically connecting the electrode assembly 500 and the terminal 200. The current collectors 400 have a shape formed by bending a single plate-like member. In other words, the current collector 400 is an L-shaped member when viewed from the Y-axis direction. As such, the current collector 400 has a simple configuration and is easy to manufacture. Because the current collector 400 can be formed from a single plate-like member, there is no need to provide a separate lead, etc., and the number of parts can be reduced. Furthermore, by reducing the space occupied by the current collectors 400 (space saving), the capacity of the energy storage element 10 can be improved.

[0038] More specifically, the current collector 400 includes a second connection portion 411 connected to the terminal 200 and a first connection portion 412 connected to the electrode assembly 500. The second connection portion 411 and the first connection portion 412 are both flat and connected to form an L-shape as described above. The current collector 400 is disposed at a position facing the electrode assembly 500 in the X-axis direction. The X-axis direction is an example of the second direction. Specifically, the main body portion 510 of the electrode assembly 500 and the first connection portion 412 of the current collector 400 face each other in the X-axis direction.

[0039] The second connecting portion 411 is a flat, rectangular portion parallel to the XY plane. The second connecting portion 411 is connected to the terminal 200 by, for example, crimping. The second connecting portion 411 is arranged in the negative Z-axis direction of the lid 120 and has a through-hole 401 through which a shaft portion 201 (see FIG. 3) of the terminal 200 passes. The shaft portion 201 is a rivet portion extending in the negative Z-axis direction from the terminal body of the terminal 200. 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 401 of the second connecting portion 411, and crimped. As a result, the current collector 400 is fixed to the lid 120 together with the terminal 200. The method for connecting the current collector 400 and the terminal 200 is not limited to crimping, and welding such as ultrasonic welding, laser welding, or resistance welding, or mechanical joining other than crimping such as screw connection may also be used.

[0040] In this embodiment, two current collectors 400 (a positive electrode current collector 400 and a negative electrode current collector 400) are arranged side by side in the X-axis direction. Hereinafter, when distinguishing between these two current collectors 400, the current collector 400 located in the positive direction of the X-axis will be referred to as a first current collector 400A, and the current collector 400 located in the negative direction of the X-axis will be referred to as a second current collector 400B. In this embodiment, the first current collector 400A is the positive electrode current collector 400, and the second current collector 400B is the negative electrode current collector 400. That is, as shown in FIG. 3 , the first current collector 400A is connected to the first terminal 210, and the second current collector 400B is connected to the second terminal 220. The first current collector 400A (positive electrode current collector) is formed of aluminum, an aluminum alloy, or the like, similar to the positive electrode current collector foil of the electrode assembly 500. The second current collector 400B (negative electrode current collector) is formed of copper, a copper alloy, or the like, similar to the negative electrode current collector foil of the electrode assembly 500.

[0041] The tab portions 520 of the electrode assembly 500 are connected to the first connection portions 412 of these two current collectors 400. As shown in FIGS. 2 and 3, the first connection portion 412 of the current collector 400 is a plate-shaped portion extending in the Z-axis direction. The Z-axis direction is an example of the first direction. More specifically, the first connection portion 412 is a flat, rectangular portion parallel to the XY plane, and the tab portions 520 of the electrode assembly 500 are connected to it by ultrasonic bonding or the like. More specifically, the two first tab portions 521 of the electrode assemblies 500A and 500B are connected to the first connection portion 412 of the first current collector 400A. The two second tab portions 523 of the electrode assemblies 500A and 500B are connected to the first connection portion 412 of the second current collector 400B. The method of connecting the first connecting portion 412 and the tab portion 520 may be ultrasonic welding, welding such as laser welding or resistance welding, or mechanical joining such as crimping or screw joining.

[0042] 3 , the first connection portion 412 and the second connection portion 411 included in the current collector 400 according to the present embodiment include a first portion 430, a second portion 440, and a third portion 450. Specifically, the first portion 430 is a portion connected to the electrode assembly 500, and the second portion 440 is a portion connected to the terminal 200. The third portion 450 is a portion of the current collector 400 between the first portion 430 and the second portion 440.

[0043] In the present embodiment, the portion of first connection portion 412 that is overlapped with tab portion 520 is treated as first portion 430, and the entire second connection portion 411 is treated as second portion 440. In current collector 400 configured in this manner, third portion 450 is disposed at a position in first connection portion 412 that is closer to second portion 440 than first portion 430. That is, in the present embodiment, third portion 450 is a part of first connection portion 412, and is a portion with a relatively large cross-sectional area. This suppresses heat generation in current collector 400.

[0044] [2. Configuration of the third part 450 of the current collector 400 and its surroundings] Next, the configuration of the third portion 450 of the current collector 400 and its surroundings will be described with reference to FIGS. 4 to 6 in addition to the above-mentioned FIGS. 2 and 3. FIG. 4 is a side view showing the configuration of an electrode assembly 500 according to an embodiment. FIG. 4 shows a simplified side view of the electrode assemblies 500A and 500B as viewed from the positive direction of the X-axis. FIG. 4 shows the electrode assemblies 500A and 500B separated in the Y-axis direction. FIG. 4 shows the two tab portions 520 bent toward each other, similar to FIG. 2. FIG. 5 is a side view showing the positional relationship between the electrode assembly 500 according to an embodiment and the first connection portion 412. FIG. 6 is a perspective view showing the configuration of a current collector 400 according to an embodiment.

[0045] 2 to 5, the main body 510 of the electrode assembly 500, which is a wound electrode assembly, includes a pair of curved portions 511 and an intermediate portion 512 between the pair of curved portions 511. When viewed from the direction of the winding axis W (see FIG. 4), the curved portion 511 is a curved portion of the laminate including the negative electrode plate, the positive electrode plate, and the separator. When viewed from the direction of the winding axis W (see FIG. 4), the intermediate portion 512 is a portion where the laminate extends linearly.

[0046] More specifically, in this embodiment, the electrode assembly 500 is a wound-type electrode assembly as described above, and has a flat shape in the Y-axis direction. The electrode assembly 500 has a winding center 519 at a position where a winding axis W parallel to the X-axis direction passes. The winding center 519 is formed, for example, by a portion located at the innermost periphery of the wound separator. In this embodiment, the portion of the main body 510 outside the winding center 519 in the Z-axis direction is treated as the curved portion 511. In other words, the portion of the main body 510 that is further in the Z-axis positive direction than the winding center 519 and the portion of the main body 510 that is further in the Z-axis negative direction than the winding center 519 are the curved portion 511.

[0047] The intermediate portion 512 of the main body portion 510 is divided into two portions: a portion located in the positive direction of the Y axis relative to the winding center portion 519, and a portion located in the negative direction of the Y axis relative to the winding center portion 519. In the present embodiment, in the electrode body 500A, the tab portion 520 is formed only in the portion of the intermediate portion 512 located in the negative direction of the Y axis relative to the winding center portion 519, and the tab portion 520 is bent in the positive direction of the Y axis. In the electrode body 500B, the tab portion 520 is formed only in the portion of the intermediate portion 512 located in the positive direction of the Y axis relative to the winding center portion 519, and the tab portion 520 is bent in the negative direction of the Y axis. The tab portion 520 bent in this manner is oriented so that the tip end of the tab portion 520 (the end opposite the main body portion 510; the same applies below) faces the Y axis direction, and the tip end is joined to the first connecting portion 412 by ultrasonic welding, laser welding, or the like. In other words, the two tab portions 520 joined to one first connection portion 412 are bent toward each other in the Y-axis direction and joined to the outer surface of the first connection portion 412 (the surface opposite the main body portion 510 of the electrode body 500). The Y-axis direction is an example of a third direction. The third direction can also be described as the thickness direction of the energy storage element 10 or the electrode body 500, the arrangement direction of the two electrode bodies 500, or the stacking direction of the electrode plates in the intermediate portion 512 of the electrode body 500.

[0048] In this embodiment, the first connecting portion 412 is a single flat plate-like portion, as shown in Figures 3, 5, and 6. In other words, the first connecting portion 412 is not divided into multiple portions aligned in the Y-axis direction by, for example, one or more grooves (also called "slits") extending in the Z-axis direction (also called "comb-tooth shape"). Therefore, the bonding area between the first connecting portion 412 and the tab portion 520 can be made relatively large.

[0049] The order of bending the tab portion 520 and joining the tab portion 520 and the first connecting portion 412 is not limited to this, and the tab portion 520 may be bent after joining the tab portion 520 and the first connecting portion 412. The joint portion where the tab portion 520 and the first connecting portion 412 are joined by welding or the like is formed in at least a part of the portion where the tab portion 520 and the first connecting portion 412 overlap when viewed from the X-axis direction (hereinafter also referred to as the "overlapping portion of the tab portion 520 and the first connecting portion 412"). The joint portion may be formed to form one continuous region in the Z-axis direction. The joint portion may be formed by a plurality of joint portions that are arranged separately from each other.

[0050] In the present embodiment, the overlapping portion of the current collector 400 between the tab portion 520 and the first connection portion 412 is treated as the first portion 430 connected to the electrode assembly 500. In other words, the first portion 430 overlapping with the tab portion 520 in the X-axis direction is composed of a portion joined to the tab portion 520 by welding or the like and a portion in contact with or close to the tab portion 520. This is not essential, and the first portion 430 may be composed of only the portion joined to the tab portion 520 by welding or the like. The first portion 430 may be the entire area of ​​the first connection portion 412 extending in the negative Z-axis direction from the third portion 450. In other words, the plate-shaped first portion 430 whose thickness direction is parallel to the X-axis direction may include a portion that does not overlap with the tab portion 520 in the X-axis direction.

[0051] Second connection portion 411 of current collector 400 is a portion joined to shaft portion 201 of terminal 200 by crimping or the like, and in this embodiment, the entire second connection portion 411 (the portion extending in a direction parallel to the XY plane) is treated as second portion 440 connected to terminal 200. This is not essential, and second portion 440 may be composed of only the portion joined to shaft portion 201 by crimping or the like. For example, second portion 440 may be the periphery of through-hole 401 in second connection portion 411.

[0052] In the current collector 400, the third portion 450 is a portion with a relatively large cross-sectional area that is disposed between the first portion 430 and the second portion 440. That is, the third portion 450 with a large cross-sectional area is disposed on the conductive path R that connects the first portion 430 connected to the electrode body 500 and the second portion 440 connected to the terminal 200 (see FIG. 6).

[0053] The "cross-sectional area" of current collector 400 is the area of ​​a cross section perpendicular to conductive path R between first portion 430 and second portion 440. In the present embodiment, the cross-sectional area of ​​third portion 450 is larger than the cross-sectional areas of portions before and after third portion 450 in the direction of conductive path R. That is, in the present embodiment, current collector 400 includes third portion 450, which is a portion on conductive path R where the cross-sectional area is larger, thereby suppressing heat generation in current collector 400. That is, the technical features of energy storage element 10 according to the present embodiment are described, for example, as follows.

[0054] The energy storage element 10 according to the present embodiment includes a terminal 200, an electrode assembly 500, and a current collector 400. The current collector 400 includes a first portion 430 connected to the electrode assembly 500, a second portion 440 connected to the terminal 200, and a third portion 450 disposed between the first portion 430 and the second portion 440. In a cross section perpendicular to the direction of the conductive path R between the first portion 430 and the second portion 440, the cross-sectional area of ​​the third portion 450 is larger than the cross-sectional areas of portions before and after the third portion 450 in the direction of the conductive path R. Specifically, as shown in FIG. 6 , the cross-sectional area of ​​the third portion 450 is defined as Sa, the cross-sectional area of ​​a first adjacent portion 455, which is closer to the first portion 430 than the third portion 450, is defined as Sb, and the cross-sectional area of ​​a second adjacent portion 456, which is closer to the second portion 440 than the third portion 450, is defined as Sc. In this case, the cross-sectional area Sa is greater than the cross-sectional area Sb, and the cross-sectional area Sa is greater than the cross-sectional area Sc.

[0055] As described above, the current collector 400 according to the present embodiment includes the third portion 450, which has a relatively large cross-sectional area, between the first portion 430 and the second portion 440. Therefore, interference between the third portion 450 and the electrode assembly 500 is suppressed, and the third portion 450 improves the heat capacity of the current collector 400. More specifically, the third portion 450, which increases the heat capacity, is disposed between the first portion 430 and the second portion 440 (i.e., on the conductive path R), which is a region where Joule heat is likely to be generated due to the flow of current. This suppresses heat generation in the current collector 400 during charging and / or discharging. Therefore, malfunctions of the energy storage element 10 caused by heat generation in the current collector 400 are suppressed. As a result, the reliability of the energy storage element 10 is improved.

[0056] The third portion 450 is characterized in that the cross-sectional area of ​​the third portion 450 is larger than the cross-sectional area of ​​the portions before and after the third portion 450 in the direction of the conductive path R, and therefore includes a portion of the current collector 400 that protrudes in a direction perpendicular to the conductive path R. Therefore, the third portion 450 also has the effect of increasing the surface area of ​​the portion of the current collector 400 where heat is likely to be generated. This allows the heat of the current collector 400 to be released efficiently.

[0057] In FIG. 6 , the portions of the current collector 400 before and after the third portion 450 in the direction of the conductive path R (the first adjacent portion 455 and the second adjacent portion 456) are not included in either the first portion 430 or the second portion 440. However, each of the first adjacent portion 455 and the second adjacent portion 456 may be included in the first portion 430 or the second portion 440. For example, when the length of the tab portion 520 in the Z-axis direction is long and the first portion 430 and the third portion 450 are continuous in the Z-axis direction, the first adjacent portion 455 may be part of the first portion 430. Alternatively, when the entire area of ​​the first connection portion 412 in the negative Z-axis direction beyond the third portion 450 is treated as the first portion 430, regardless of whether the length of the tab portion 520 in the Z-axis direction is long, the first adjacent portion 455 may be part of the first portion 430.

[0058] That is, the first adjacent portion 455 and the second adjacent portion 456, which are used to compare the cross-sectional area of ​​the third portion 450, may be portions adjacent to the protruding portion, that is, the third portion 450, in the direction of the conductive path R. That is, the first adjacent portion 455 and the second adjacent portion 456 may or may not be included in the first portion 430 or the second portion 440.

[0059] One of the cross-sectional area Sb of the first adjacent portion 455 and the cross-sectional area Sc of the second adjacent portion 456 may be larger than the other, or may be the same as the other. In the present embodiment, the cross-sectional area Sb and the cross-sectional area Sc are substantially the same. The current collector 400 may include a portion other than the third portion 450 that has a cross-sectional area larger than the cross-sectional area Sa of the third portion 450. In other words, even if the current collector 400 includes a portion that has a cross-sectional area larger than the cross-sectional area Sa, the effect of the third portion 450 in suppressing heat generation from the current collector 400 is not lost.

[0060] In the present embodiment, the current collector 400 includes a plate-shaped first connection portion 412 extending in the Z-axis direction. The first connection portion 412 includes a first portion 430 and a third portion 450. The electrode assembly 500 includes a pair of curved portions 511 facing each other in the Z-axis direction and an intermediate portion 512 between the pair of curved portions 511 (see FIGS. 2 to 5). The intermediate portion 512 includes a tab portion 520 protruding in the X-axis direction intersecting the Z-axis direction. The first portion 430 faces the intermediate portion 512 in the X-axis direction and is connected to the tab portion 520. The third portion 450 faces one of the pair of curved portions 511 in the X-axis direction. Specifically, as shown in FIGS. 2 and 5, the third portion 450 faces the curved portion 511 of the pair of curved portions 511 that is closer to the second portion 440 in the X-axis direction.

[0061] In the present embodiment, the intermediate portion 512 in the main body 510 of the electrode assembly 500 is a portion extending in the Z-axis direction as shown in FIGS. 4 and 5 . Therefore, by providing the tab portion 520, in which multiple tabs 528 (see FIG. 6 ) overlap, in the intermediate portion 512, it is possible to form the tab portion 520 having a flat shape along the XZ plane. This makes it difficult to apply unnecessary load to the tab portion 520 when joining the tab portion 520 to the first connection portion 412, which is flat and extends in the Z-axis direction. Furthermore, as shown in FIG. 6 and other figures, it is also easy to bend the tab portion 520 in the Y-axis direction. Therefore, the tab portion 520 is disposed within the range of the intermediate portion 512 in the Z-axis direction, and is not disposed in the curved portion 511. In the present embodiment, the third portion 450, which has a relatively large cross-sectional area, is disposed at a position opposite in the X-axis direction to the curved portion 511 where the tab portion 520 is not disposed. This more reliably suppresses interference between the tab portion 520 and the third portion 450.

[0062] In the present embodiment, as shown in FIG. 5 , the width W1 of the third portion 450 in the Y-axis direction is larger than the width W2 of the front and rear portions of the third portion 450 in the Y-axis direction. In the present embodiment, the Y-axis direction is a direction intersecting the direction of the conductive path R and the opposing direction of the current collector 400 and the electrode assembly 500 (the X-axis direction in the present embodiment). In the present embodiment, the widths of the front and rear portions of the third portion 450 in the Y-axis direction, i.e., the widths of the first adjacent portion 455 and the second adjacent portion 456 (see FIG. 6 ) in the Y-axis direction, are W2, which is the same. This is not essential, and the widths of the first adjacent portion 455 and the second adjacent portion 456 in the Y-axis direction may be different from each other. In this case, the larger of the widths of the first adjacent portion 455 and the second adjacent portion 456 in the Y-axis direction may be treated as the width W2 of the front and rear portions of the third portion 450 in the Y-axis direction.

[0063] In this way, the third portion 450 of the current collector 400 according to the present embodiment has a large width in the Y-axis direction, which is not the opposing direction (X-axis direction) of the current collector 400 and the electrode assembly 500, and therefore the cross-sectional area Sa of the third portion 450 is larger than the cross-sectional areas Sb and Sc before and after it. Therefore, interference between the third portion 450 and the electrode assembly 500 is more reliably suppressed.

[0064] More specifically, as shown in FIG. 5, the third portion 450 according to this embodiment has a shape that protrudes on both sides in the Y-axis direction more than the front and rear portions of the third portion 450 in the direction of the conductive path R.

[0065] According to this configuration, even if the width of third portion 450 in the Z-axis direction cannot be increased due to circumstances such as a narrow width of curved portion 511 of electrode body 500, a relatively large heat dissipation area can be ensured by making third portion 450 protrude on both sides in the Y-axis direction. Third portion 450 with a large width in the Y-axis direction has a shape that protrudes on both sides in the Y-axis direction in current collector 400. Therefore, problems of interference with other components (for example, the inner surface of container 100) that can occur when third portion 450 protrudes on only one side in the Y-axis direction are unlikely to occur.

[0066] The above has described the energy storage element 10 according to the embodiment, focusing on the configuration of the current collector 400. However, the configuration of the current collector 400 included in the energy storage element 10 may be different from the configurations shown in FIGS. 2 to 6, and the energy storage element 10 may be used as an energy storage element included in an energy storage device. Therefore, below, modifications of the energy storage element 10 will be described, focusing on the differences from the above embodiment. Current collectors 400a and 400b according to modifications 1 and 2 described below are current collectors that can be included in the energy storage element 10 instead of or in addition to the current collector 400 according to the embodiment.

[0067] [3-1. Variation 1] 7 is a perspective view showing the configuration of a current collector 400a according to Modification 1 of the embodiment. The current collector 400a according to this modification includes a first portion 430 connected to the electrode assembly 500, a second portion 440 connected to the terminal 200, and a third portion 450a disposed between the first portion 430 and the second portion 440. In a cross section perpendicular to the direction of the conductive path R between the first portion 430 and the second portion 440, the cross-sectional area of ​​the third portion 450a is larger than the cross-sectional areas of the portions before and after the third portion 450a in the direction of the conductive path R. These configurations are common to the current collector 400 according to the embodiment.

[0068] In the current collector 400a of this modified example, the third portion 450a has a shape that protrudes more than the front and rear portions of the third portion 450a on both sides in the X-axis direction, and in this respect, it differs from the current collector 400 of the embodiment.

[0069] That is, the third portion 450a protrudes in the opposing direction of the first connection portion 412 of the current collector 400a and the main body portion 510 of the electrode body 500 (see FIG. 3). Even in this case, the third portion 450a, which increases the heat capacity, is disposed between the first portion 430 and the second portion 440, which are areas where Joule heat is likely to be generated due to the flow of current. This suppresses heat generation in the current collector 400a during charging and / or discharging. This suppresses malfunctions of the energy storage element 10 caused by heat generation in the current collector 400a.

[0070] The third portion 450a according to this modification does not protrude toward the pair of long side wall portions 112 (see FIG. 3) of the container body 110, and therefore, for example, when the distance between the pair of long side wall portions 112 is narrow, the third portion 450a is less likely to interfere with the pair of long side wall portions 112. The third portion 450a is disposed at a position facing the curved portion 511 (see FIG. 4) in the X-axis direction, and therefore interference between the third portion 450a and the tab portion 520 is suppressed.

[0071] Third portion 450a may have a shape that protrudes only in the positive direction or the negative direction of the X-axis. Even in this case, the cross-sectional area of ​​third portion 450a can be made larger than the cross-sectional area of ​​the portions before and after third portion 450a in the direction of conductive path R. When third portion 450a has a shape that protrudes only in the positive direction of the X-axis, interference between third portion 450a and electrode body 500 is more reliably suppressed.

[0072] [3-2. Variation 2] 8 is a perspective view showing the configuration of a current collector 400b according to Modification 2 of the embodiment. The current collector 400b according to this modification includes a first portion 430 connected to the electrode assembly 500, a second portion 440 connected to the terminal 200, and a third portion 450b disposed between the first portion 430 and the second portion 440. In a cross section perpendicular to the direction of the conductive path R between the first portion 430 and the second portion 440, the cross-sectional area of ​​the third portion 450b is larger than the cross-sectional areas of the portions before and after the third portion 450b in the direction of the conductive path R. These configurations are common to the current collector 400 according to the embodiment.

[0073] In current collector 400b according to this modification, third portion 450b is provided on current collector 400b as part of second connection portion 411, and in this respect, current collector 400b differs from current collector 400 according to the embodiment.

[0074] That is, in the current collector 400b according to this modification, the second portion 440 connected to the terminal 200 is a portion of the second connection portion 411 that includes the through-hole 401, as shown in FIG. 8 . The end of the second connection portion 411 that is closer to the first connection portion 412 (the end in the positive direction of the X-axis) is used as the third portion 450b. Therefore, in this modification, the second portion 440 and the third portion 450b are continuously disposed in the direction of the conductive path R. Even in this case, the third portion 450b, which increases the heat capacity, is disposed between the first portion 430 and the second portion 440, which are regions where Joule heat due to current flow is likely to be generated. Therefore, heat generation in the current collector 400b during charging and / or discharging is suppressed. Therefore, malfunctions of the energy storage element 10 caused by heat generation in the current collector 400b are suppressed.

[0075] Because the third portion 450b according to this modification is part of the second connection portion 411 that contacts the lower gasket 320, the heat of the third portion 450b can be conducted to the container 100 via the lower gasket 320. This allows the heat of the current collector 400b to be more efficiently released to the outside of the energy storage element 10. Because the third portion 450b does not protrude toward the electrode assembly 500, interference between the third portion 450b and the electrode assembly 500 is more reliably suppressed.

[0076] [3-3. Variation 3] The energy storage elements 10 according to the above-described embodiments 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. 9 is a plan view schematically illustrating an example of an energy storage device 900 according to a third modified example of the embodiment. As illustrated in FIG. 9, a plurality of energy storage units 800 are arranged inside the energy storage device 900. The energy storage unit 800 is composed of a plurality of electrically connected energy storage elements 10. The energy storage device 900 may include a bus bar (not shown) that electrically connects the plurality of energy storage elements 10, a bus bar (not shown) that electrically connects the plurality of energy storage units 800, and the like. The energy storage unit 800 or the energy storage device 900 may include a state monitoring device (not shown) that monitors the state of one or more energy storage elements 10. The energy storage device 900 may include only one energy storage unit 800. In other words, the energy storage unit 800 may be referred to as an energy storage device. The energy storage device 900 may include the energy storage elements 10 according to the first or second modification instead of or in addition to the energy storage elements 10 according to the above embodiment.

[0077] [4. Description of other modifications] Although 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.

[0078] In the embodiment, the first connection portion 412 of the current collector 400 is a flat portion whose thickness direction is oriented in the X-axis direction. However, the first connection portion of the current collector 400 may be a flat portion whose thickness direction is oriented in the Y-axis direction. In this case, the tab portion 520 of the electrode body 500 may be joined to the first connection portion in a state where it extends in the protruding direction of the tab portion 520. In this case, the current collector 400 may be provided with two first connection portions to which two tab portions 520 (e.g., two first tab portions 521) extending in the same direction are joined. In either case, by providing the current collector 400 with a third portion having a cross-sectional area larger than the cross-sectional areas of the front and rear portions in the direction of the conductive path R, heat generation of the current collector 400 during charging and / or discharging is suppressed.

[0079] When the first connection portion is a flat portion with its thickness direction oriented in the Y-axis direction, the third portion may have a shape that protrudes to both sides or one side in the Y-axis direction. This allows, for example, current collector 400 to be provided with a third portion that suppresses heat generation of current collector 400 without increasing the maximum width in the X-axis direction.

[0080] The shape and size of third portion 450 included in current collector 400 do not have to be the shape and size shown in Fig. 5 and Fig. 6. For example, third portion 450 may have a shape that protrudes beyond the front and rear portions of third portion 450 on only one side in the Y-axis direction. The shape of the portion of third portion 450 that protrudes beyond the front and rear portions of third portion 450 may be triangular, semicircular, or the like, instead of the rectangular shape shown in Fig. 5 and Fig. 6.

[0081] The current collector 400 may include two or more third portions 450. For example, the current collector 400 including the third portion 450 (see FIGS. 5 and 6) may further include the third portion 450b according to Modification 2 (see FIG. 8). This makes it possible to more reliably suppress heat generation from the current collector 400.

[0082] It is not essential that both of the pair of current collectors 400 (see FIG. 3 ) included in the energy storage element 10 include the third portion 450. For example, consider a case where one of the first current collector 400A and the second current collector 400B is more likely to generate heat than the other due to differences in the properties (volume resistivity, thermal conductivity, etc.) of the materials forming the first current collector 400A of the positive electrode and the second current collector 400B of the negative electrode. In this case, only one of the first current collector 400A and the second current collector 400B may include the third portion 450.

[0083] The tab portion 520 of the electrode body 500 may be joined to the inner surface of the first connecting portion 412 (the surface facing the main body portion 510 of the electrode body 500) by ultrasonic bonding or the like. As shown in Fig. 2, when two tab portions 520 are joined to the first connecting portion 412, one of the two tab portions 520 may be joined to the inner surface of the first connecting portion 412, and the other of the two tab portions 520 may be joined to the outer surface of the first connecting portion 412 (the surface opposite to the main body portion 510 of the electrode body 500).

[0084] In the above embodiment, the electrode body 500 is provided in the energy storage device 10 with the winding axis W parallel to the X-axis direction, but this is not essential. For example, the electrode body 500 may be provided in the energy storage device 10 with the winding axis W parallel to the Z-axis direction. In this case, the first connection portion 412 of the current collector 400 may face the main body portion 510 in the Z-axis direction, and the terminal 200 may be disposed on the short side wall portion 111.

[0085] The number of electrode bodies 500 included in the energy storage device 10 is not limited to two. The energy storage device 10 may include only one electrode body 500. The energy storage device 10 may include, for example, three or more electrode bodies 500 lined up in the Y-axis direction. When the energy storage device 10 includes three or more electrode bodies 500 lined up in the Y-axis direction, the current collector 400 may include three or more first connection portions 412 lined up in the Y-axis direction, each of which is connected to one or two electrode bodies 500.

[0086] In the above embodiment, the tab portion 520 is formed only in a portion of the intermediate portion 512 of the electrode body 500 that is in the negative Y-axis direction relative to the winding center portion 519, or only in a portion of the intermediate portion 512 that is in the positive Y-axis direction relative to the winding center portion 519. However, the tab portion 520 may be formed on both sides of the winding center portion 519 in the Y-axis direction of the main body portion 510.

[0087] The electrode body 500 is not limited to a wound type electrode body. The electrode body 500 may be a laminated type (stack type) electrode body formed by stacking a plurality of flat electrode plates, a bellows type electrode body in which electrode plates are folded in a bellows shape, or an electrode body of another form.

[0088] The various supplementary points regarding the current collector 400 according to the embodiment described above may be appropriately applied to the current collectors 400a and 400b according to Modifications 1 and 2. Configurations constructed by arbitrarily combining the components included in the above embodiment and its modifications are also included within the scope of the present invention. [Industrial Applicability]

[0089] The present invention can be applied to an electric storage device such as a lithium ion secondary battery. [Explanation of symbols]

[0090] 10. Energy storage element 200 terminals 201 Shaft 400, 400a, 400b current collector 400A first current collector 400B Second current collector 411 Second connection part 412 First connection part 430 Part 1 440 Part 2 450, 450a, 450b Part 3 455 First adjacent section 456 Second adjacent section 500, 500A, 500B electrode body 510 Main body 511 Curved section 512 Middle section 519 Center of winding 520 Tab section 521 First tab part 523 Second tab part 528 tabs R Conduction path Sa, Sb, Sc cross section

Claims

1. A terminal, an electrode body, and a current collector are provided, The current collector is a first portion connected to the electrode body; a second part connected to the terminal; a third portion disposed between the first portion and the second portion, In a cross section perpendicular to a direction of the conductive path between the first part and the second part, a cross-sectional area of ​​the third part is larger than cross-sectional areas of portions before and after the third part in the direction of the conductive path. Energy storage element.

2. the current collector includes a first connection portion including the first portion and the third portion, the first connection portion having a plate shape extending in a first direction, The electrode body includes a pair of curved portions facing each other in the first direction and an intermediate portion between the pair of curved portions, the intermediate portion includes a tab portion that protrudes in a second direction intersecting the first direction, the portion faces the intermediate portion in the second direction and is connected to the tab portion; the third portion faces one of the pair of curved portions in the second direction; The energy storage element according to claim 1 .

3. the third portion has a width in a third direction intersecting the direction of the conductive path and the opposing direction of the current collector and the electrode body that is larger than the width of the front and rear portions in the third direction; The energy storage element according to claim 1 or 2.

4. The third portion has a shape that protrudes more than the front and rear portions on both sides in the third direction. The energy storage element according to claim 3 .

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