Power storage element

Abstract

To provide a power storage element with improved reliability.SOLUTION: A power storage element includes an electrode body 700 having a wound electrode plate 715, and including an electrode body main body 710 and a connection portion 730 protruding from an end of the electrode body main body 710 in a first direction parallel to the winding axis of the electrode plate 715, the connection portion 730 including a plurality of tabs 720 that are part of the electrode plate stacked in a second direction perpendicular to the first direction.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a power storage element.

Background Art

[0002] Patent Document 1 discloses a battery including a container, an electrode group housed in the container and including a positive electrode and a negative electrode, a plurality of current collecting tabs extending from a plurality of locations of a current collector of at least one of the positive electrode and the negative electrode of the electrode group and laminated in the thickness direction, and a lead electrically connected to the current collecting tab. The electrode group has a flat shape and is produced, for example, by winding a separator between the positive electrode and the negative electrode in a spiral shape and then pressure-molding the whole into a flat shape. From one side half circumference of one end face of the electrode group, the current collecting tab of the positive electrode is led out upward, and the current collecting tab of the negative electrode is led out upward.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the electrode group included in the above conventional battery, the positive electrode and the negative electrode are wound in a spiral shape with a separator interposed therebetween. In an electrode group having such a structure, for example, due to variations in the thickness of the positive electrode and the negative electrode, a problem occurs in that the displacement in the winding direction of each of the plurality of current collecting tabs laminated in the thickness direction becomes larger toward the outer periphery. The displacement of the current collecting tab becomes a factor of problems such as interference between the current collecting tab and other members. On the other hand, from the viewpoint of suppressing an increase in electrical resistance, it is preferable that the width of the current collecting tab in the winding direction is larger. However, considering that the displacement of the current collecting tab occurs as described above, it is difficult to increase the lateral width of the current collecting tab.

[0005] The present invention has been made by the inventors of the present application newly paying attention to the above problems, and an object thereof is to provide a power storage element with improved reliability.

Means for Solving the Problems

[0006] The power storage element according to one aspect of the present invention includes an electrode body having wound electrode plates. The electrode body includes an electrode body main body and a connection portion. The connection portion is an end portion of the electrode body main body and protrudes from an end portion in a first direction parallel to the winding axis of the electrode plate. The connection portion includes a plurality of tabs that are a part of the electrode plate laminated in a second direction orthogonal to the first direction. The plurality of tabs include a first tab closest to the winding axis in the second direction. In a third direction orthogonal to the first direction and the second direction, the width of the first tab is the largest among the plurality of tabs.

[0007] The power storage element according to another aspect of the present invention includes an electrode body having wound electrode plates. The electrode body includes an electrode body main body and a connection portion. The connection portion is an end portion of the electrode body main body and protrudes from an end portion in a first direction parallel to the winding axis of the electrode plate. The connection portion includes a plurality of tabs that are a part of the electrode plate laminated in a second direction orthogonal to the first direction. The width of the connection portion in the third direction increases from one far from the winding axis to the other close to the winding axis in the second direction.

Effects of the Invention

[0008] According to the present invention, a power storage element with improved reliability can be provided.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

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Figure 7

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Figure 9

Figure 10

MODE FOR CARRYING OUT THE INVENTION

[0010] (1) The power storage element according to one aspect of the present invention includes an electrode body including wound electrode plates, the electrode body includes an electrode body main body and a connection part, the connection part is an end part of the electrode body main body and protrudes from an end part in a first direction parallel to the winding axis of the electrode plates, the connection part includes a plurality of tabs which are a part of the electrode plates laminated in a second direction orthogonal to the first direction, the plurality of tabs include a first tab closest to the winding axis in the second direction, and in a third direction orthogonal to the first direction and the second direction, the width of the first tab is the largest among the plurality of tabs.

[0011] According to the energy storage element according to one aspect of the present invention, the width of the first tab at the position closest to the winding axis in the second direction is the largest among the plurality of tabs. Specifically, in the wound electrode plate included in the electrode body, the first tab at the position closest to the winding axis in the second direction is less likely to deviate from the designed position in the third direction. Therefore, the width of the first tab in the third direction can be made relatively large, thereby suppressing, for example, the electrical resistance of the connection portion. In this way, the reliability of the energy storage element according to this aspect is improved.

[0012] (2) In the energy storage element according to (1) above, the plurality of tabs may include a second tab that is farthest from the winding axis in the second direction, and the width of the second tab in the third direction may be the smallest among the plurality of tabs.

[0013] According to the energy storage element according to (2) above, when the electrode plate is wound, the second tab disposed on the outermost periphery, which is most likely to deviate from the designed position, has the smallest width among the plurality of tabs in the third direction. Therefore, an increase in the width of the connection portion in the third direction is more reliably suppressed.

[0014] (3) In the energy storage element according to (2) above, the width of the connection portion in the third direction may increase from one side that is far from the winding axis in the second direction to the other side that is close to the winding axis.

[0015] According to the energy storage element according to (3) above, the connection portion, which is an aggregate of a plurality of stacked tabs, as a whole, has a larger (wider) width in the third direction from one side far from the winding axis (the portion far from the winding axis) to the other side close to the winding axis (the portion close to the winding axis). Therefore, suppression of an increase in the electrical resistance of the connection portion and suppression of an increase in the width of the connection portion in the third direction are more balancedly achieved.

[0016] (4) In the energy storage element according to (2) or (3) above, when viewed from the second direction, the entire area of the second tab in the third direction may overlap with the first tab.

[0017] According to the energy storage element described in (4) above, the width of the second tab in the third direction is smaller than the width of the first tab in the third direction, and the entire third direction overlaps with the first tab. Therefore, when the width of the first tab in the third direction is relatively large, an increase in the width of the connection portion in the third direction is more reliably suppressed.

[0018] (5) In the energy storage element described in (4) above, when viewed from the second direction, it is also possible that the entire third direction of all other tabs other than the first tab among the plurality of tabs overlaps with the first tab.

[0019] According to the energy storage element described in (5) above, when viewed from the second direction, all of the plurality of tabs included in the connection portion are included in the range of the width of the first tab in the third direction. Therefore, the width of the connection portion in the third direction is substantially the same as the width of the first tab in the third direction. Accordingly, the occurrence of problems such as interference between the connection portion and other members due to an increase in the width of the connection portion in the third direction is more reliably suppressed.

[0020] (6) The energy storage element according to another aspect of the present invention includes an electrode body including wound electrode plates, the electrode body includes an electrode body main body and a connection portion, the connection portion is an end portion of the electrode body main body and protrudes from an end portion in a first direction parallel to the winding axis of the electrode plates, the connection portion includes a plurality of tabs that are a part of the electrode plates laminated in a second direction orthogonal to the first direction, and the width of the connection portion in a third direction orthogonal to the first direction and the second direction increases from one far from the winding axis to the other close to the winding axis in the second direction.

[0021] According to the energy storage element according to another aspect of the present invention, the width of the connection portion including a plurality of tabs laminated in the second direction in the third direction increases from one side in the second direction (the portion of the connection portion far from the winding axis in the second direction) to the other side (the portion of the connection portion close to the winding axis in the second direction). That is, when viewed as a whole, the width of the connection portion in the third direction increases as it approaches the winding axis in the second direction. That is, by relatively increasing the width of the tab in the third direction, which is less likely to be displaced due to being close to the winding axis, for example, an increase in the electrical resistance of the connection portion, heat generation during energization, and / or occurrence of problems when the connection portion is bent are suppressed. Further, by relatively reducing the width of the tab in the third direction, which is likely to be displaced due to being far from the winding axis, an increase in the width of the connection portion in the third direction is suppressed. As a result, problems such as interference between the connection portion and other members due to an increase in the width of the connection portion in the third direction are less likely to occur. Thus, the energy storage element according to this aspect is an energy storage element with improved reliability.

[0022] Hereinafter, an energy storage element according to an embodiment (including its modified examples) of the present invention will be described with reference to the drawings. Note that all of the embodiments described below show comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, manufacturing processes, order of manufacturing processes, etc. shown in the following embodiments are merely examples and are not intended to limit the present invention. Also, in each drawing, the dimensions and the like are not strictly illustrated. Further, in each drawing, the same or similar components are denoted by the same reference numerals.

[0023] In the following description and drawings, the arrangement direction of a pair of terminals of the power storage element, the arrangement direction of a pair of current collectors, or the facing direction of a pair of short side surfaces of the container is defined as the X-axis direction. The facing direction of a pair of long side surfaces of the container, the stacking direction of the electrode plates of the electrode body, or the thickness direction of the container is defined as the Y-axis direction. The arrangement direction of the container body and the lid of the power storage element, or the longitudinal direction of the short side surface of the container is defined as the Z-axis direction. These X-axis direction, Y-axis direction, and Z-axis direction are directions that intersect (orthogonal in this embodiment) with each other. Depending on the usage mode, there may be cases where the Z-axis direction does not become the vertical direction, but hereinafter, for convenience of explanation, the Z-axis direction will be described as the vertical direction.

[0024] In the following description, for example, the X-axis plus direction indicates the arrow direction of the X-axis, and the X-axis minus direction indicates the direction opposite to the X-axis plus direction. The same applies to the Y-axis direction and the Z-axis direction. When simply referring to the "X-axis direction", it means a bidirectional direction parallel to the X-axis or either one of the directions. The same applies to the terms related to the Y-axis and Z-axis.

[0025] Furthermore, expressions indicating relative directions or postures such as parallel and orthogonal also include cases where they are not strictly in that direction or posture. For example, when it is said that two directions are orthogonal, it means not only that the two directions are completely orthogonal, but also that they are substantially orthogonal, that is, for example, including a difference of about several percent. In the following description, when expressing "insulation", it means "electrical insulation". The insulating material is preferably formed from a material having a volume resistivity of 1 × 10 10 Ωm or more.

[0026] (Embodiment) [1. General description of the power storage element] First, with reference to FIGS. 1 and 2, a general description of the power storage element 10 in this embodiment will be given. FIG. 1 is a perspective view showing the appearance of the power storage element 10 according to the embodiment. FIG. 2 is an exploded perspective view of the power storage element 10 according to the embodiment.

[0027] The energy storage element 10 is a secondary battery, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is used, for example, as a battery for driving a moving body such as an automobile, a motorcycle, a watercraft, a ship, a snowmobile, an agricultural machine, a construction machine, an automatic guided vehicle (AGV), or a railway vehicle for electric railways, or for engine starting. Examples of the above-mentioned automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, light oil, liquefied natural gas, etc.) automobiles. Examples of the above-mentioned railway vehicles for electric railways include trains, monorails, linear motor cars, and hybrid trains equipped with both a diesel engine and an electric motor. Further, the energy storage element 10 can also be used as a stationary battery for household or commercial use, etc.

[0028] The energy storage element 10 is not limited to non-aqueous electrolyte secondary batteries, and may be a secondary battery other than non-aqueous electrolyte secondary batteries, or may be a capacitor. The energy storage element 10 may be a primary battery.

[0029] As shown in FIG. 1, the energy storage element 10 includes a container 100, a pair of terminals 200, and a pair of external insulating members 300. As shown in FIG. 2, an electrode body 700, a pair of current collectors 500, and a pair of internal insulating members 400 are housed inside the container 100. Although a non-aqueous electrolyte, which is an electrolytic solution, is enclosed inside the container 100, the illustration is omitted. The type of the electrolytic solution 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. Further, spacers, insulating films, etc. (not shown) may be arranged inside the container 100.

[0030] The container 100 is a rectangular parallelepiped-shaped case. Here, a rectangular parallelepiped refers to a hexahedron composed of all rectangular or square faces. The container 100 has a container body 110 and a lid 120 that closes the opening of the container body 110. After the electrode body 700 is housed inside the container body 110, the container body 110 and the lid 120 are welded or the like, and the inside of the container 100 is sealed. The materials of the container body 110 and the lid 120 are not particularly limited, but weldable metals such as stainless steel, aluminum, aluminum alloy, iron, and plated steel sheets are preferred.

[0031] The container body 110 is a member having a rectangular tubular shape with a bottom, and an opening is formed at the upper part. The container body 110 has a pair of short side faces 112 on both sides in the X-axis direction, a pair of long side faces 113 on both sides in the Y-axis direction, and a bottom face 114 in the negative Z-axis direction. The lid 120 is a rectangular plate-like member that closes the opening of the container body 110. A gas discharge valve 122 for discharging the gas inside the container 100 when the internal pressure of the container 100 rises excessively is arranged on the lid 120. The lid 120 may further be provided with a liquid injection port or the like for injecting an electrolytic solution into the container 100.

[0032] The electrode body 700 includes a positive electrode plate, a negative electrode plate, and a separator, and is a power storage element (power generation element) that can store electricity. The electrode body 700 includes an electrode body main body 710 and a pair of connection parts 730 provided on one side in the Z-axis direction of the electrode body main body 710. The connection part 730 is a part also called a "tab part" for example, and includes a plurality of tabs laminated in the Y-axis direction. Hereinafter, when distinguishing the connection parts 730 of the positive electrode and the negative electrode, the connection part 730 of the negative electrode is described as the connection part 730A, and the connection part 730 of the positive electrode is described as the connection part 730B. Details of the configuration of the electrode body 700 will be described later with reference to FIGS. 3 to 5.

[0033] In the present embodiment, a current collector 500 is joined to each of the pair of connection portions 730 as shown in FIG. 2. For example, the connection portion 730 is bent so that the tip portion of the connection portion 730 faces the +Y axis direction, and the surface of the current collector 500 in the -Z axis direction and the connection portion 730 are joined. As a method of joining the current collector 500 and the connection portion 730, for example, ultrasonic welding is employed. There is no particular limitation on the joining method, and laser welding, resistance welding, caulking, or the like may be employed as the joining method.

[0034] The terminal 200 is a member that is electrically connected to the electrode body 700 via the current collector 500. Specifically, one of the pair of terminals 200 is electrically connected to the positive electrode plate of the electrode body 700, and the other of the pair of terminals 200 is electrically connected to the negative electrode plate of the electrode body 700. The terminal 200 is attached to a lid body 120 disposed above the electrode body 700. Specifically, the terminal 200 has a shaft portion 201 that penetrates the lid body 120. The shaft portion 201 of the terminal 200 is inserted into and caulked in the through hole 301 of the external insulating member 300, the through hole 123 of the lid body 120, the through hole 401 of the internal insulating member 400, and the through hole 501 of the current collector 500. Thereby, the terminal 200 is fixed to the lid body 120 together with the external insulating member 300, the internal insulating member 400, and the current collector 500. The terminal 200 is formed of aluminum, an aluminum alloy, copper, a copper alloy, or the like.

[0035] The external insulating member 300 is a member that insulates the lid body 120 and the terminal 200. In the present embodiment, the external insulating member 300 also functions as a gasket that seals the space between the lid body 120 and the shaft portion 201 of the terminal 200. The internal insulating member 400 is a member that insulates the lid body 120 and the current collector 500. Each of the external insulating member 300 and the internal insulating member 400 is formed of a resin material having electrical insulation properties.

[0036] The current collector 500 is a flat member that electrically connects the electrode body 700 and the terminal 200. Specifically, the current collector 500 integrally includes a portion joined to the terminal 200 by caulking or the like and a portion connected to the connection portion 730 of the electrode body 700 by welding or the like. The current collector 500 is formed of a metal such as aluminum, an aluminum alloy, copper, or a copper alloy. The method of connecting the current collector 500 and the terminal 200 is not limited to caulking, and methods such as ultrasonic bonding, laser welding, resistance welding, or the connection of bolts and nuts may be employed.

[0037] In the present embodiment, the current collector 500 is a flat member parallel to the XY plane, but the shape and size of the current collector 500 are not particularly limited. For example, the current collector 500 may include a connection surface portion that forms a connection surface parallel to the XZ plane. In this case, the connection surface portion may be connected to the connection portion 730 (see FIG. 2) extended in the +Z-axis direction by ultrasonic bonding or the like.

[0038] [2. Configuration of Electrode Body 700] Next, the configuration of the electrode body 700 according to the present embodiment will be described. FIG. 3 is a perspective view showing the configuration of the electrode body 700 according to the embodiment. In FIG. 3, the wound electrode plates 715 and the like in the electrode body 700 are partially unfolded and illustrated. FIG. 4 is a top view (viewed from the +Z-axis direction) schematically showing the configuration of the connection portion 730 according to the embodiment. In FIG. 4, the configuration of the electrode plate 715, which is the negative electrode plate 715A among the components of the electrode body 700, is simply illustrated, and the illustration of the separator 718 and the positive electrode plate 715B is omitted. In FIG. 4, each of the plurality of tabs 720 of the electrode plate 715 is represented by a rectangle elongated in the X-axis direction with a pattern for easy understanding. These supplementary matters regarding FIG. 4 are also applicable to FIGS. 6 to 9 described later.

[0039] FIG. 5 is a diagram schematically showing the relationship between the position of tab 720 and the lateral width of tab 720 in the electrode plate 715 according to the embodiment. The lateral width of tab 720 is the width of tab 720 in the longitudinal direction of electrode plate 715. In the present embodiment, since tab 720 is located in the flat portion of the wound electrode body 700, the lateral width of tab 720 is the width of tab 720 in the winding direction of electrode plate 715, which is the width in the X-axis direction in the embodiment. The starting end portion 716a, which is the end portion of electrode plate 715 in the negative X-axis direction shown in FIG. 5, is the end portion closer to the winding axis P in the Y-axis direction and is the starting end portion of the winding of electrode plate 715. The ending end portion 716b, which is the end portion of electrode plate 715 in the positive X-axis direction shown in FIG. 5, is the end portion farther from the winding axis P in the Y-axis direction and is the end portion located on the outermost periphery of the wound electrode plate 715 (the ending end portion of the winding of electrode plate 715).

[0040] As shown in FIG. 3, the electrode body 700 according to the present embodiment is formed by alternately laminating and winding a pair of electrode plates 715, i.e., a negative electrode plate 715A and a positive electrode plate 715B, with a separator 718 interposed therebetween. The winding axis P represented by the two-dot chain line in FIG. 3 is a virtual axis that serves as the central axis when winding the negative electrode plate 715A, the positive electrode plate 715B, the separator 718, etc. In the present embodiment, the winding axis P is parallel to the Z-axis direction. The Z-axis direction is an example of the first direction. The electrode body 700 is formed in a flat shape in a direction orthogonal to the winding axis P. That is, the electrode body 700 is a wound and flat-shaped electrode body. In the present embodiment, as shown in FIGS. 2 and 3, the electrode body 700 has a flat shape in the Y-axis direction. The Y-axis direction is an example of the second direction. The X-axis direction is an example of the third direction orthogonal to the first direction and the second direction.

[0041] The negative electrode plate 715A includes a negative electrode current collector foil which is a long strip-shaped metal foil, and a negative electrode active material layer formed on the surface of the negative electrode current collector foil. The positive electrode plate 715B includes a positive electrode current collector foil which is a long strip-shaped metal foil, and a positive electrode active material layer formed on the surface of the positive electrode current collector foil. In the electrode body 700, the negative electrode active material layer of the negative electrode plate 715A and the positive electrode active material layer of the positive electrode plate 715B are laminated via the separator 718, thereby forming the electrode body main body 710. The separator 718 is wound around the outermost periphery of the electrode body main body 710 for one or more turns.

[0042] As the positive electrode current collector foil and the negative electrode current collector foil, known materials can be appropriately used as long as they are materials stable against oxidation-reduction reactions during charge and discharge, such as nickel, iron, stainless steel, titanium, fired carbon, conductive polymer, conductive glass, and Al-Cd alloy. As the positive electrode active material used in the positive electrode active material layer and the negative electrode active material used in the negative electrode active material layer, known materials can be appropriately used as long as they are positive electrode active materials and negative electrode active materials capable of occluding and releasing charge transport ions.

[0043] The separator 718 is a microporous sheet made of resin. In addition, as the material of the separator 718 used in the power storage element 10, known materials can be appropriately used as long as they do not impair the performance of the power storage element 10.

[0044] As shown in FIG. 5, each of the pair of electrode plates 715 includes an electrode plate main body portion 716 on which a negative electrode active material layer or a positive electrode active material layer is formed, and a tab 720 which is a portion where the current collector foil is exposed. More specifically, a plurality of tabs 720 protruding from the side in the short side direction (Z-axis direction) are arranged on the electrode plate main body portion 716. The plurality of tabs 720 are arranged side by side at a predetermined interval in the longitudinal direction of the electrode plate main body portion 716.

[0045] More specifically, the negative electrode plate 715A includes a plurality of tabs 720a, and the positive electrode plate 715B includes a plurality of tabs 720b. When the negative electrode plate 715A is wound, the tabs 720a are stacked in the Y-axis direction, thereby forming the connection portion 730A. When the positive electrode plate 715B is wound, the tabs 720b are stacked in the Y-axis direction, thereby forming the connection portion 730B. As shown in FIGS. 2 and 3, the connection portion 730A and the connection portion 730B are arranged on one side in the Y-axis direction with respect to the winding axis P at one end in the Z-axis direction of the electrode body main body 710. In the present embodiment, the connection portion 730A and the connection portion 730B are arranged on the minus Y-axis direction with respect to the winding axis P at the end in the plus Z-axis direction of the electrode body main body 710. The connection portion 730A and the connection portion 730B are arranged apart from each other in the X-axis direction.

[0046] As described above, in the wound electrode body 700, when the electrode plate 715 is wound, the tabs 720 arranged in the longitudinal direction of the electrode plate 715 are stacked, thereby forming the connection portion 730. Therefore, the interval between two adjacent tabs 720 is formed on the electrode plate 715 so as to become longer as it moves away from the winding axis P so as to align the positions of the plurality of tabs 720 in the winding direction. For example, as shown in FIG. 5, when the center of the width of the tab 720 in the X-axis direction is defined as the position of the tab 720 in the X-axis direction, the interval between two adjacent tabs 720 becomes longer as it approaches the end portion 716b from the start end portion 716a. That is, as shown in FIG. 5, the electrode plate 715 includes n (n is an integer of 2 or more) tabs 720 that form one connection portion 730, and the tab interval, which is the interval between two adjacent tabs 720, is T1, T2, ···, T n-1 When defined as such, these tab intervals satisfy T1 < T2 < ··· < T n-1

[0047] ​In this way, by adjusting the tab intervals in the plurality of tabs 720, it is possible in calculation to align the positions of the plurality of tabs 720 stacked in the Y-axis direction in the X-axis direction. However, in reality, it is difficult to align the positions of the plurality of tabs 720 in the X-axis direction due to the influence of variations in the thickness of the electrode plate 715 or the like. When the positions of the plurality of tabs 720 in the X-axis direction vary, the lateral width of the connection portion 730, which is an aggregate of the plurality of stacked tabs 720, increases. As a result, there is a risk of problems such as interference between the connection portion 730 and other members. To solve this problem, for example, it is conceivable to reduce the width of each of the plurality of tabs 720 in the X-axis direction. Thereby, even when the positions of the plurality of tabs 720 in the X-axis direction vary, an increase in the lateral width of the connection portion 730, which is an aggregate of the plurality of stacked tabs 720, is suppressed.

[0048] However, from the viewpoints of suppressing an increase in the electrical resistance of the connection portion 730, suppressing heat generation during energization, or suppressing the occurrence of defects such as breakage of the tab 720 during the manufacture of the energy storage element 10, it is preferable that the width of the tab 720 is larger. Therefore, as a means for suppressing an increase in the lateral width of the connection portion 730, reducing the width of each of the plurality of tabs 720 is not preferable from the viewpoints of suppressing an increase in the electrical resistance and the like.

[0049] Therefore, in the present embodiment, a configuration is adopted in which the width in the X-axis direction of the tab 720 closest to the winding axis P in the Y-axis direction, which is the tab 720 most likely to be arranged at the designed position among the plurality of tabs 720 provided in the electrode plate 715, is made the largest.

[0050] That is, the energy storage element 10 according to the present embodiment includes an electrode body 700 including wound electrode plates 715. The electrode body 700 includes an electrode body main body 710 and a connection portion 730. The connection portion 730 is an end portion of the electrode body main body 710 and protrudes from an end portion in the Z-axis direction parallel to the winding axis P of the electrode plate 715. The connection portion 730 includes a plurality of tabs 720 which are a part of the electrode plate 715 laminated in the Y-axis direction orthogonal to the Z-axis direction. The plurality of tabs 720 includes a first tab 721 closest to the winding axis P in the Y-axis direction. In the X-axis direction orthogonal to the Z-axis direction and the Y-axis direction, the width of the first tab 721 is the largest among the plurality of tabs 720. Specifically, in the present embodiment, as shown in FIGS. 4 and 5, when the tab 720 closest to the winding axis P in the Y-axis direction is taken as the first tab 721, the width W1 of the first tab 721 in the X-axis direction is the largest among the widths (W1, W2, W3, ···, W n ) of all the tabs 720. The first tab 721 can also be described as the tab 720 closest to the start end portion 716a (see FIG. 5) of the electrode plate 715 among the plurality of tabs 720.

[0051] In the present embodiment, in the electrode body 700, the electrode plate 715 including the plurality of tabs 720 is wound. Therefore, the position of the first tab 721 at the position closest to the winding axis P in the Y-axis direction is less likely to deviate from the designed position in the X-axis direction. Therefore, the width W1 of the first tab 721 in the X-axis direction can be made relatively large. That is, even when the width W1 of the first tab 721 is made relatively large, problems such as interference between the first tab 721 and other members are less likely to occur. In this way, since the width W1 of the first tab 721 in the X-axis direction is relatively large, an increase in the electrical resistance of the connection portion 730, heat generation during energization, and / or occurrence of defects in the first tab 721 when the connection portion 730 is bent are suppressed. Note that when even one of these effects is achieved, the reliability of the energy storage element is improved. The more effects are achieved, the more the reliability of the energy storage element can be further improved.

[0052] Furthermore, the widths (W2, W3, ···, W of one or more tabs 720 other than the first tab 721 in the X-axis direction n) is smaller than the width W1 of the first tab 721 in the X-axis direction. Therefore, even when the position of the one or more tabs 720 in the X-axis direction deviates from the design value, an increase in the width of the connecting portion 730 in the X-axis direction can be suppressed. As a result, problems such as interference between the connecting portion 730 and other members due to an increase in the width of the connecting portion 730 in the X-axis direction are less likely to occur. Thus, the power storage element 10 according to the present embodiment is a power storage element with improved reliability. The power storage element 10 according to the present embodiment has the effect of suppressing the occurrence of problems such as an increase in the electrical resistance of the connecting portion 730, heat generation during energization, and / or problems with the first tab 721 when the connecting portion 730 is bent, and the effect of making it less likely for problems such as interference between the connecting portion 730 and other members to occur. By combining these effects, the reliability of the power storage element is further improved.

[0053] When the width W1 of the first tab 721 in the X-axis direction is the largest among the widths of all the tabs 720 in the X-axis direction, for one or more tabs 720 that are farther from the winding axis P than the first tab 721, the width in the X-axis direction only needs to be smaller than W1. For example, among any two tabs 720 other than the first tab 721, the width of the tab 720 closer to the winding axis P in the X-axis direction may be smaller than the width of the other tab 720 among the two tabs 720. However, from the perspective of achieving a good balance between suppressing an increase in the electrical resistance of the connecting portion 730 and suppressing an increase in the width of the connecting portion 730 in the X-axis direction, it is preferable for the connecting portion 730 to have the following technical features.

[0054] The connecting portion 730 included in the electrode body 700 according to the present embodiment more specifically has the following technical features.

[0055] In the present embodiment, the plurality of tabs 720 include a second tab 722 that is the farthest from the winding axis P in the Y-axis direction. In the X-axis direction, the width of the second tab 722 is the smallest among the plurality of tabs 720. Specifically, in the present embodiment, as shown in FIGS. 4 and 5, when the tab 720 that is the farthest from the winding axis P in the Y-axis direction is used as the second tab 722, the width W of the second tab 722 in the X-axis direction n is the width (W1, W2, W3, ···, W) of all the tabs 720 in the X-axis directionn ) is the smallest among them. The second tab 722 can also be described as the tab 720 that is the farthest from the starting end 716a (see FIG. 5) of the electrode plate 715 among the plurality of tabs 720, or the tab 720 that is the closest to the ending end 716b of the electrode plate 715.

[0056] Thus, in this embodiment, when the electrode plate 715 is wound, the width of the second tab 722, which is the outermost peripheral tab 720 that is most likely to deviate from the designed position, is the smallest in the X-axis direction among the plurality of tabs 720. Therefore, an increase in the width of the connecting portion 730 in the X-axis direction is more reliably suppressed.

[0057] It is not essential that the width of the second tab 722 in the X-axis direction is the smallest among the plurality of tabs 720. The width of the second tab 722 in the X-axis direction may be the second smallest or the third smallest among the plurality of tabs 720. In any case, if the width of the first tab 721 in the X-axis direction is the largest among the plurality of tabs 720, it is less likely that problems such as interference between the connecting portion 730 and other members will occur due to an increase in the width of the connecting portion 730 in the X-axis direction. However, from the perspective of more reliably suppressing an increase in the width of the connecting portion 730 in the X-axis direction, it is preferable that the width of the second tab 722 is the smallest in the X-axis direction among the plurality of tabs 720.

[0058] In this embodiment, the width of the connecting portion 730 in the X-axis direction increases from the one farther from the winding axis P in the Y-axis direction to the one closer to the winding axis P as shown in FIG. 4, for example.

[0059] Thus, in this embodiment, the connecting portion 730, which is an aggregate of the stacked tabs 720, has an increasing width in the X-axis direction as a whole when viewed from the Y-axis minus direction to the Y-axis plus direction. That is, when focusing on one tab 720, it is difficult for the tab 720 to protrude in the X-axis direction from other tabs 720 closer to the winding axis P than the tab 720. Therefore, suppression of an increase in the electrical resistance of the connecting portion 730 and suppression of an increase in the width of the connecting portion 730 in the X-axis direction are more balancedly realized.

[0060] In the present embodiment, as can be seen from FIGS. 2 and 4, for example, when viewed from the Y-axis direction, the entire X-axis direction of the second tab 722 overlaps with the first tab 721.

[0061] Thus, in the present embodiment, the width W of the second tab 722 in the X-axis direction n is smaller than the width W1 of the first tab 721 in the X-axis direction, and the entire X-axis direction overlaps with the first tab 721. That is, when viewed from the Y-axis direction, the second tab 722 does not protrude in the X-axis direction with respect to the first tab 721. Therefore, for example, when the width of the first tab 721 in the X-axis direction is relatively large, an increase in the width of the connecting portion 730 in the X-axis direction is more reliably suppressed.

[0062] More specifically, in the present embodiment, when viewed from the Y-axis direction, the entire X-axis direction of all the other tabs 720 other than the first tab 721 among the plurality of tabs 720 overlaps with the first tab 721.

[0063] That is, when viewed from the Y-axis direction, all the tabs 720 other than the first tab 721 included in the connecting portion 730 are included in the range of the width W1 of the first tab 721 in the X-axis direction. Therefore, the width of the connecting portion 730 in the X-axis direction is substantially the same as the width W1 of the first tab 721 in the X-axis direction. Accordingly, the occurrence of problems such as interference between the connecting portion 730 and other members due to an increase in the width of the connecting portion 730 in the X-axis direction is more reliably suppressed.

[0064] As described above, the configuration of the connecting portion 730 of the electrode body 700 of the energy storage element 10 according to the embodiment has been mainly described. However, the connecting portion 730 of the electrode body 700 included in the energy storage element 10 may have a configuration different from the configuration shown in FIGS. 2 to 5, and the energy storage element 10 may be used as an energy storage element provided in an energy storage device. Therefore, hereinafter, modification examples related to the energy storage element 10 will be described centering on the differences from the above embodiment. The electrode bodies 700 including the connecting portions 730a to 730d according to Modification Examples 1 to 4 described below can all be electrode bodies included in the energy storage element 10.

[0065] [3-1. Modification Example 1] FIG. 6 is a top view schematically showing the configuration of the connection portion 730a according to Modification Example 1 of the embodiment. Similar to the connection portion 730 according to the embodiment, the connection portion 730a according to this modification example includes the first tab 721 that is closest to the winding axis P in the Y-axis direction, and in the X-axis direction, the first tab 721 has the largest width W1 among the plurality of tabs 720. Therefore, according to the connection portion 730a according to this modification example, effects such as suppression of an increase in the electrical resistance of the connection portion 730a can be obtained, and an increase in the width of the connection portion 730a in the X-axis direction is suppressed.

[0066] In the connection portion 730a according to this modification example, it is different from the connection portion 730 (see FIG. 4) according to the embodiment in that the central positions of the plurality of tabs 720 in the X-axis direction are shifted in the X-axis direction. Even in this case, since the width W1 of the first tab 721 in the X-axis direction is larger than the widths of all the other tabs 720 in the X-axis direction, for example, all of the plurality of tabs 720 included in the connection portion 730a are included in the range of the width W1 of the first tab 721 in the X-axis direction. Therefore, an increase in the width of the connection portion 730a in the X-axis direction is suppressed.

[0067] [3-2. Modification Example 2] FIG. 7 is a top view schematically showing the configuration of the connection portion 730b according to Modification Example 2 of the embodiment. Similar to the connection portion 730 according to the embodiment, the connection portion 730b according to this modification example includes the first tab 721 that is closest to the winding axis P in the Y-axis direction, and in the X-axis direction, the first tab 721 has the largest width W1 among the plurality of tabs 720.

[0068] More specifically, in the connection part 730b according to this modification example, among the plurality of tabs 720, the widths in the X-axis direction of the three tabs 720 that are closer to the winding axis P in the Y-axis direction are the same. In other words, the first tab 721 is one of the three tabs 720 whose width in the X-axis direction is W1. Even in this case, since the three tabs 720 are located closer to the winding axis P in the Y-axis direction, it is difficult to deviate from the designed position in the X-axis direction. Therefore, according to the connection part 730b of this modification example, while suppressing an increase in the width in the X-axis direction, effects such as suppressing an increase in the electrical resistance of the connection part 730b can be obtained. That is, among the plurality of tabs 720 included in the connection part 730b, the number of tabs 720 having the maximum width in the X-axis direction may be two or more including the first tab 721. However, from the viewpoint of suppressing an increase in the width in the X-axis direction of the connection part 730b, it is preferable that the number of tabs 720 having the maximum width in the X-axis direction is small. Therefore, the number of tabs 720 having the maximum width in the X-axis direction is preferably, for example, 1 or more and not more than half of the number of tabs 720 included in the connection part 730b, and more preferably not more than 1 / 3.

[0069] [3-3. Modification Example 3] FIG. 8 is a top view schematically showing the configuration of a connection part 730c according to Modification Example 3 of the embodiment. Similar to the connection part 730 according to the embodiment, the connection part 730c according to this modification example includes a first tab 721 that is closest to the winding axis P in the Y-axis direction, and in the X-axis direction, the first tab 721 has the largest width W1 among the plurality of tabs 720. Further, the connection part 730c includes a second tab 722 that is farthest from the winding axis P in the Y-axis direction, and in the X-axis direction, the second tab 722 has the smallest width W n among the plurality of tabs 720.

[0070] More specifically, in the connection part 730c according to this modification example, among the plurality of tabs 720, the widths in the X-axis direction of the three tabs 720 that are farther from the winding axis P in the Y-axis direction are the same. In other words, the second tab 722 is one of the tabs 720 whose width in the X-axis direction is W nIt is one of the three tabs 720. Even in this case, since the width of the three tabs 720 in the X-axis direction is small, even if the position in the X-axis direction deviates from the design value, it is difficult for the width of the connection part 730c in the X-axis direction to increase. Therefore, according to the connection part 730c according to this modification example, effects such as suppression of an increase in the electrical resistance of the connection part 730c can be obtained, and an increase in the width of the connection part 730c in the X-axis direction is suppressed. That is, among the plurality of tabs 720 included in the connection part 730c, the number of tabs 720 with the smallest width in the X-axis direction may be 2 or more including the second tab 722. For example, when the number of the plurality of tabs 720 is 30, the number of tabs 720 with the smallest width in the X-axis direction may be at most 29. In this case, from the viewpoint of suppressing an increase in the width of the connection part 730c in the X-axis direction, the larger the number of tabs 720 with the smallest width in the X-axis direction, the easier it is for the tabs other than the first tab 721 to be included in the range of the width W1 of the first tab 721 in the X-axis direction.

[0071] [3-4. Modification Example 4] FIG. 9 is a top view schematically showing the configuration of a connection part 730d according to a modification example 4 of the embodiment. Different from the connection part 730 according to the embodiment, the first tab 721 closest to the winding axis P in the Y-axis direction in the connection part 730d according to this modification example does not have the largest width among the plurality of tabs 720. Specifically, the tab 720 second closest to the winding axis P in the Y-axis direction has the largest width W2 among the plurality of tabs 720.

[0072] Even in this case, the connection part 730d, which is an aggregate of laminated tabs 720, has a width in the X-axis direction that increases from the Y-axis minus direction to the Y-axis plus direction as a whole. Therefore, suppression of an increase in the electrical resistance of the connection part 730d and suppression of an increase in the width of the connection part 730d in the X-axis direction are more balancedly realized.

[0073] That is, the energy storage element 10 according to this modification includes an electrode body 700 including wound electrode plates 715. The electrode body 700 includes an electrode body main body 710 and a connection portion 730d. The connection portion 730d is an end portion of the electrode body main body 710 and protrudes from an end portion in the Z-axis direction parallel to the winding axis P of the electrode plate 715. The connection portion 730d includes a plurality of tabs 720 which are a part of the electrode plate 715 laminated in the Y-axis direction orthogonal to the Z-axis direction. The width of the connection portion 730d in the X-axis direction orthogonal to the Z-axis direction and the Y-axis direction increases from one side far from the winding axis P in the Y-axis direction to the other side close to the winding axis P.

[0074] That is, when viewed as a whole, the width of the connection portion 730d in the X-axis direction increases as it approaches the winding axis P in the Y-axis direction. That is, by relatively increasing the width of the tab 720 in the X-axis direction, which is less likely to be displaced due to being close to the winding axis P, an increase in the electrical resistance of the connection portion 730d, heat generation during energization, and / or occurrence of problems when the connection portion 730d is bent are suppressed. Further, by relatively reducing the width of the tab 720 in the X-axis direction, which is likely to be displaced due to being far from the winding axis P, an increase in the width of the connection portion 730d in the X-axis direction is suppressed. As a result, problems such as interference between the connection portion 730d and other members due to an increase in the width of the connection portion 730d in the X-axis direction are less likely to occur.

[0075] Regarding each of the connection portions 730 (see FIG. 4) according to the embodiment and the connection portions 730a, 730b, and 730c (see FIGS. 6 to 8) according to Modifications 1 to 3, it may also be described that the width in the X-axis direction increases from one side far from the winding axis P in the Y-axis direction to the other side close to the winding axis P.

[0076] In FIG. 9, the width W2 of the tab 720 that is the second closest to the winding axis P in the Y-axis direction is the width (W1, W2, ···, W n) is the largest among them, but this is not essential. That is, the position of the tab 720 in the Y-axis direction is less likely to cause a displacement in the X-axis direction if it is closer to the winding axis P. Therefore, it is preferable that the order of the tabs 720 with the largest width in the X-axis direction is in the order closer to the winding axis P in the Y-axis direction. That is, the position of the tab 720 with the largest width in the X-axis direction is more preferable if it is closer to the winding axis P in the Y-axis direction. For example, among the n tabs 720, the order of the tab 720 with the largest width in the X-axis direction is preferably within the m-th (m is 30% of n) from the one closer to the winding axis P in the Y-axis direction. That is, when the connecting portion 730d includes 10 tabs 720, the widths (W1, W2, ···, W 10 ) Among them, it is preferable that any one of W1, W2, and W3, which are the widths in the X-axis direction of the tabs 720 that are the 1st to 3rd closest to the winding axis P, is the largest. More preferably, the order of the tab 720 with the largest width in the X-axis direction is within the m-th (m is 20% of n) from the one closer to the winding axis P in the Y-axis direction. Even more preferably, like the connecting portion 730 according to the embodiment, the order of the tab 720 with the largest width in the X-axis direction is the 1st from the one closer to the winding axis P in the Y-axis direction.

[0077] For the plurality of tabs 720 that are farther from the winding axis P in the Y-axis direction than the tab 720 with the largest width in the X-axis direction, it is preferable that the width in the X-axis direction becomes smaller as it moves farther from the winding axis P. For example, in the connecting portion 730d, when the number of tabs 720 is 10 and the width W2 is the largest, W2 > W3 > W4 > W5 > W6 > W7 > W8 > W9 > W 10 is preferable. However, this is not essential. For example, W2 > W3 > W4 = W5 <w6>W7 > W8 > W9 > W 10 This may be the case. In this case, for example, if W3 < W6, it may be described that the width of the connecting portion 730d in the X-axis direction increases from one side far from the winding axis P in the Y-axis direction to the other side close to the winding axis P.

[0078] It is not essential that the width of the connecting portion 730 in the X-axis direction increases from one side far from the winding axis P in the Y-axis direction to the other side close to the winding axis P. That is, in terms of appearance, it may not be recognized that the shape of the connecting portion 730 increases from one side far from the winding axis P in the Y-axis direction to the other side close to the winding axis P. Even in this case, if the width of the first tab 721 in the X-axis direction is the largest among the plurality of tabs 720, it is difficult for problems such as interference between the connecting portion 730 and other members to occur due to an increase in the width of the connecting portion 730 in the X-axis direction.

[0079] [3-5. Modification Example 5] FIG. 10 is a plan view schematically showing the configuration of the power storage device 900 according to Modification Example 5 of the embodiment. As shown in FIG. 10, the power storage element 10 according to the above embodiment may be used in the power storage device 900. In this case, the technology of the present invention may be applied to at least one power storage element 10 included in the power storage device 900.

[0080] The power storage device 900 shown in FIG. 10 includes a plurality of power storage units 800 arranged inside. The power storage unit 800 is composed of a plurality of electrically connected power storage elements 10. The power storage device 900 may include a bus bar (not shown) for electrically connecting the plurality of power storage elements 10, and a bus bar (not shown) for electrically connecting the plurality of power storage units 800, etc. The power storage unit 800 or the power storage device 900 may include a state monitoring device (not shown) for monitoring the state of one or more power storage elements 10. The power storage device 900 may include only one power storage unit 800. In this case, the power storage unit 800 may be referred to as a "power storage device".

[0081] In this modification example, the power storage device 900 includes one or more of the power storage elements 10 according to the above-described embodiment. However, the power storage device 900 may include the power storage element 10 according to any one of Modification Examples 1 to 4 instead of or in addition to the one or more power storage elements 10.

[0082] [4. Other Modification Examples] As described above, the power storage element and its modification examples according to the embodiment of the present invention have been described. However, the present invention is not limited to the embodiment and the modification examples. That is, it should be considered that the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of the present invention is intended to include all changes within the meaning and scope equivalent to the claims.

[0083] Regarding the various features of the connection portion 730 described in the embodiment, and regarding the various features of each of the connection portions 730a to 730d described in Modification Examples 1 to 4, at least one of the connection portion 730A of the negative electrode and the connection portion 730B of the positive electrode included in the electrode body 700 may have them.

[0084] The shape of the tab 720 when viewed from the Y-axis direction does not have to be rectangular as shown in FIG. 5. The shape of the tab 720 when viewed from the Y-axis direction may be, for example, trapezoidal such that the width in the X-axis direction decreases as it moves away from the electrode plate main body portion 716. In this case, the width in the X-axis direction of the edge in the +Z-axis direction, which is the tip portion of the tab 720, that is, the length of the side corresponding to the upper base (<lower base) of the trapezoid, may be defined as the width of the tab 720 in the X-axis direction. The root portion of the tab 720 when viewed from the Y-axis direction may be, for example, tapered.

[0085] When viewed from the Y-axis direction, it is not essential that the entire region of the second tab 722 in the X-axis direction overlaps with the first tab 721. That is, when viewed from the Y-axis direction, a part of the second tab 722 in the X-axis direction may not overlap with the first tab 721. In this case, by the width of the first tab 721 in the X-axis direction being the largest among the plurality of tabs 720, it becomes difficult for problems such as interference between the connection portion 730 and other members to occur due to an increase in the width of the connection portion 730 in the X-axis direction.

[0086] When viewed from the Y-axis direction, it is not essential that all the tabs 720 other than the first tab 721 among the plurality of tabs 720 provided in the connecting portion 730 are included in the width range of the first tab 721 in the X-axis direction. For example, one or more of all the other tabs 720 may protrude from the width range of the first tab 721 in the X-axis direction. Even in this case, since the width of all the other tabs 720 in the X-axis direction is smaller than the width of the first tab 721, problems such as interference between the connecting portion 730 and other members are less likely to occur due to an increase in the width of the connecting portion 730 in the X-axis direction. However, from the viewpoint of more reliably suppressing the occurrence of problems such as interference between the connecting portion 730 and other members, it is preferable that the number of tabs 720 included in the width range of the first tab 721 in the X-axis direction is large when viewed from the Y-axis direction.

[0087] The electrode body 700 included in the power storage element 10 may be provided with a pair of connecting portions 730 protruding in different directions from each other. For example, the electrode body 700 may include a negative electrode connecting portion 730A at an end portion of the electrode body main body 710 in the +Z-axis direction, and a positive electrode connecting portion 730B at an end portion of the electrode body main body 710 in the -Z-axis direction. In this case, a terminal 200 electrically connected to the negative electrode connecting portion 730A may be arranged at an end portion of the container 100 in the +Z-axis direction, and a terminal 200 electrically connected to the positive electrode connecting portion 730B may be arranged at an end portion of the container 100 in the -Z-axis direction.

[0088] There is no particular limitation on the posture of the electrode body 700 in the power storage element 10. For example, the electrode body 700 may be housed in the container 100 in a posture where the winding axis P is parallel to the X-axis direction. In this case, the electrode body 700 may include a connecting portion 730 at each of both end portions of the electrode body main body 710 in the X-axis direction. Further, in this case, the current collector may include a terminal connecting portion connected to the shaft portion 201 of the terminal 200, and a leg portion extending in the -Z-axis direction from the terminal connecting portion and connected to the connecting portion 730. That is, the electrode body 700 may be a horizontally wound electrode body wound so that the winding axis P is parallel to the Z-axis direction, or a vertically wound electrode body wound so that the winding axis P is parallel to the X-axis direction.

[0089] The power storage element 10 may include only one of a pair of terminals 200. For example, assume a case where the connection portion 730B of the positive electrode of the electrode body 700 is electrically connected to the container 100, that is, a case where the container 100 is used as a positive electrode terminal. In this case, the power storage element 10 may include only the terminal 200 that is electrically connected to the connection portion 730A of the negative electrode among the pair of terminals 200.

[0090] The current collector 500 connected to the connection portion 730 of the electrode body 700 may not be directly connected to the terminal 200. For example, the current collector 500 may be connected by a conductive member directly connected to the terminal 200 and welding or caulking or the like.

[0091] The number of connection portions 730 connected to the current collector 500 may be two or more. For example, when two connection portions 730A of negative electrodes arranged in the Y-axis direction or the X-axis direction are provided at the end portion of the electrode body main body 710 in the +Z-axis direction, the two connection portions 730A may be connected to the current collector 500 by a predetermined method such as ultrasonic bonding.

[0092] It is not essential that the shaft portion 201 is provided on the terminal 200. For example, a shaft portion provided integrally with the current collector 500 may penetrate the internal insulating member 400, the lid body 120, the external insulating member 300, and the terminal 200, and may be caulked outside the terminal 200.

[0093] The supplementary matters regarding 730 according to the above embodiment may be applied to the connection portions 730a to 730d according to Modifications 1 to 4. A form constructed by arbitrarily combining the components included in the above embodiment and its modifications is also included within the scope of the present invention.

Industrial Applicability

[0094] The present invention can be applied to a power storage element such as a lithium ion secondary battery.

Explanation of Reference Numerals

[0095] 10 Energy storage element 100 Container 500 Current collector 700 Electrode body 710 Electrode body main body 715 Electrode plate 715A Negative electrode plate 715B Positive electrode plate 716 Electrode plate main body part 716a Starting end part 716b Ending end part 718 Separator 720, 720a, 720b Tab 721 First tab 722 Second tab 730, 730A, 730B, 730a, 730b, 730c, 730d Connection part 800 Energy storage unit 900 Energy storage device

Claims

1. Comprising an electrode body having wound electrode plates, The electrode body includes an electrode body main body and a connection portion, The connection portion is an end portion of the electrode body main body and protrudes from an end portion in a first direction parallel to the winding axis of the electrode plate, The connection portion includes a plurality of tabs which are part of the electrode plate and are laminated in a second direction orthogonal to the first direction, The plurality of tabs includes a first tab closest to the winding axis in the second direction, In a third direction orthogonal to the first direction and the second direction, the width of the first tab is the largest among the plurality of tabs, An energy storage element.

2. The plurality of tabs includes a second tab farthest from the winding axis in the second direction, In the third direction, the width of the second tab is the smallest among the plurality of tabs, The energy storage element according to Claim 1.

3. The width of the connection portion in the third direction increases from one farther from the winding axis to the other closer to the winding axis in the second direction, The energy storage element according to Claim 2.

4. When viewed from the second direction, the entire area of the second tab in the third direction overlaps with the first tab, The energy storage element according to Claim 2 or 3.

5. When viewed from the second direction, the entire area of all other tabs other than the first tab among the plurality of tabs in the third direction overlaps with the first tab, The energy storage element according to Claim 4.

6. Comprising an electrode body having wound electrode plates, The electrode body includes an electrode body main body and a connection portion, The connection portion is an end portion of the electrode body main body and protrudes from an end portion in a first direction parallel to the winding axis of the electrode plate, The connection portion includes a plurality of tabs which are part of the electrode plate and are laminated in a second direction orthogonal to the first direction, The width of the connection portion in a third direction orthogonal to the first direction and the second direction increases from one farther from the winding axis to the other closer to the winding axis in the second direction, An energy storage element.

Images