Power storage element

Abstract

This power storage element comprises an electrode body, a first conductive member, and a second conductive member. The electrode body comprises an electrode main body, and a tab part provided at one end of the electrode main body in a first direction. The tab part comprises a tab connection part bent in a second direction crossing the first direction. The first conductive member comprises a first connection part connected to the tab connection part, and a second connection part connected to the second conductive member. When viewed from one side in the first direction, the first connection part and the second connection part are arranged in a third direction crossing the first direction and the second direction, and the second connection part is disposed on one side of the first connection part in the first direction.

Description

Energy storage element

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

[0002] Patent Document 1 discloses a battery including a battery case, an electrode assembly, a positive electrode terminal, a first positive electrode current collector, and a second positive electrode current collector. In this battery, the positive electrode tab group of the electrode assembly and the positive electrode terminal are electrically connected via the first positive electrode current collector and the second positive electrode current collector. Specifically, the positive electrode tab group and the second positive electrode current collector are joined. Furthermore, the first positive electrode current collector and the second positive electrode current collector, which are fixed to a sealing plate of the battery case, are joined. For example, welding using high-energy rays such as a laser is used to join the first positive electrode current collector and the second positive electrode current collector.

[0003] JP 2023-15681 A

[0004] In the conventional battery, the joint between the positive electrode first current collector and the positive electrode second current collector is located closer to the main body of the electrode assembly (the portion other than the positive electrode tab group and the negative electrode tab group) than the joint between the positive electrode second current collector and the positive electrode tab group. Therefore, heat generated during the formation of the joint can adversely affect the electrode assembly, potentially compromising the quality of the 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 quality.

[0006] An energy storage element according to one aspect of the present invention comprises an electrode body, a first conductive member, and a second conductive member, wherein the electrode body comprises an electrode body main body and a tab portion provided at one end of the electrode body main body in a first direction, the tab portion comprising a tab connection portion bent in a second direction intersecting the first direction, the first conductive member comprising a first connection portion connected to the tab connection portion and a second connection portion connected to the second conductive member, wherein when viewed from one side of the first direction, the first connection portion and the second connection portion are aligned in a third direction intersecting the first direction and the second direction, and the second connection portion is positioned further towards the one side of the first direction than the first connection portion.

[0007] According to the present invention, it is possible to provide an energy storage element with improved quality.

[0008] FIG. 1 is a perspective view showing the appearance of an energy storage element according to an embodiment. FIG. 2 is an exploded perspective view of an energy storage element according to an embodiment. FIG. 3 is a perspective view showing a current collector and its peripheral configuration according to an embodiment. FIG. 4 is a cross-sectional view showing a current collector and its peripheral configuration according to an embodiment. FIG. 5 is a cross-sectional view showing a current collector and its peripheral configuration according to a first modified example of an embodiment. FIG. 6 is a cross-sectional view showing a current collector and its peripheral configuration according to a second modified example of an embodiment. FIG. 7 is a plan view schematically showing the configuration of an energy storage device including an energy storage element according to an embodiment.

[0009] (1) An energy storage element according to one aspect of the present invention comprises an electrode body, a first conductive member, and a second conductive member, wherein the electrode body comprises an electrode body main body and a tab portion provided at one end of the electrode body main body in a first direction, the tab portion comprising a tab connection portion bent in a second direction intersecting the first direction, the first conductive member comprising a first connection portion connected to the tab connection portion and a second connection portion connected to the second conductive member, wherein, when viewed from one side of the first direction, the first connection portion and the second connection portion are aligned in a third direction intersecting the first direction and the second direction, and the second connection portion is positioned further towards the one side of the first direction than the first connection portion.

[0010] In an energy storage element according to one aspect of the present invention, the second connection portion is disposed on one side of the first connection portion in the first direction. That is, the second connection portion is disposed at a position farther from the electrode body main body in the first direction than the first connection portion. Therefore, the adverse effects of heat generated during the connection process (e.g., welding, the same applies hereinafter) between the second connection portion and the second conductive member on the electrode body main body can be suppressed. In this way, the energy storage element according to one aspect of the present invention is an energy storage element with improved quality.

[0011] (2) In the energy storage device described in (1) above, the first conductive member may include a bent portion between the first connection portion and the second connection portion.

[0012] According to the energy storage element described in (2) above, for example, by bending a plate-shaped metal material, a first conductive member having a shape in which the second connection portion is disposed to one side of the first connection portion in the first direction can be produced. This makes it easy to produce the first conductive member. Furthermore, the positions of the first connection portion and the second connection portion can be arbitrarily changed or appropriately modified. In other words, the design freedom of the first conductive member is increased.

[0013] (3) In the energy storage element described in (1) or (2) above, the thickness in the first direction of at least a portion of the second connection portion may be smaller than the thickness in the first direction of the first connection portion.

[0014] According to the energy storage element described in (3) above, at least a portion of the second connection portion is provided as a thin-walled portion on the first conductive member. This reduces the energy required to connect the second connection portion and the second conductive member. In other words, the connection operation becomes easier and adverse effects on the electrode body can be further reduced.

[0015] (4) In the energy storage element described in any one of (1) to (3) above, the first connection portion may have a first opposing surface facing the electrode body main body, the second connection portion may have a second opposing surface facing the electrode body main body, and the second opposing surface may be positioned on one side of the first direction relative to the first opposing surface.

[0016] According to the energy storage element described in (4) above, the second opposing surface of the second connection part is positioned farther from the electrode body main body in the first direction than the first opposing surface of the first connection part. In particular, the second opposing surface is a surface facing the electrode body main body, and heat may adversely affect a certain area of ​​the electrode body main body. Therefore, the adverse effect of heat generated during the connection operation between the second connection part and the second conductive member on the electrode body main body can be more reliably suppressed.

[0017] (5) In the energy storage element described in any one of (1) to (4) above, the second connection portion may have an outer surface facing one side of the first direction, the first connection portion may be arranged between the tab connection portion and the electrode body main body, the tab connection portion may have a tab side surface facing one side of the first direction, and the outer surface may be arranged at the same position as the tab side surface in the first direction or on the other side of the first direction than the tab side surface.

[0018] According to the energy storage element described in (5) above, the outer surface of the second connection portion is disposed in the first direction at the same position as the tab side surface of the tab connection portion or at a position closer to the electrode body main body than the tab side surface of the tab connection portion, thereby preventing the second connection portion from excessively protruding in one direction in the first direction beyond the first connection portion, and enabling the energy storage element to be miniaturized.

[0019] Hereinafter, with reference to the drawings, an energy storage element according to an embodiment of the present invention will be described. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples and are not intended to limit the present invention. Furthermore, in each drawing, dimensions and the like are not strictly illustrated. Furthermore, in each drawing, the same or similar components are assigned the same reference numerals.

[0020] In the following description and drawings, the X-axis direction is defined as the direction in which a pair of terminals (positive and negative electrodes, hereinafter the same) of the energy storage element are arranged, the direction in which a pair of current collectors are arranged, or the direction in which a pair of short side surfaces of the container face each other. The Y-axis direction is defined as the direction in which a pair of long side surfaces of the container face each other, the stacking direction of the electrode plates of the electrode body, or the thickness direction of the container. The Z-axis direction is defined as the direction in which the container body and lid of the energy storage element are arranged, or the longitudinal direction of the short side surfaces of the container. The X-axis direction, Y-axis direction, and Z-axis direction intersect each other (orthogonal in this embodiment). Depending on the usage mode, the Z-axis direction may not be the up-down direction, but for convenience of explanation, the following description will be made assuming that the Z-axis direction is the up-down direction.

[0021] In the following description, for example, the positive X-axis direction refers to the direction of the arrow on the X-axis, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. The same applies to the Y-axis and Z-axis directions. When simply referring to the "X-axis direction," it means either one or both directions parallel to the X-axis. The same applies to terms related to the Y-axis and Z-axis.

[0022] Furthermore, expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the directions or attitudes are not strictly the same. For example, "two directions are perpendicular" does not only mean that the two directions are completely perpendicular, but also means that the two directions are substantially perpendicular, i.e., that there is a difference of, for example, about a few percent. In the following description, when the term "insulation" is used, it means "electrical insulation." An insulating material has a volume resistivity of 1×10 １０ It is preferable that the material be made of a material with a resistance of Ωm or more.

[0023] (Embodiment) [1. General Description of Energy Storage Element] First, an energy storage element 10 according to the present embodiment will be generally described with reference to Fig. 1 and Fig. 2. Fig. 1 is a perspective view showing the appearance of the energy storage element 10 according to the embodiment. Fig. 2 is an exploded perspective view of the energy storage element 10 according to the embodiment.

[0024] The energy storage element 10 is a secondary battery, more specifically, a nonaqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is used as a battery for driving or starting the engine of a mobile object such as an automobile, motorcycle, personal watercraft, ship, snowmobile, agricultural machinery, construction machinery, automatic guided vehicle (AGV), or electric railway vehicle. Examples of the automobile include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicles. Examples of the electric railway vehicle include electric trains, monorails, linear motor cars, and hybrid electric trains equipped with both a diesel engine and an electric motor. The energy storage element 10 can also be used as a stationary battery for home or business use.

[0025] 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 also be a primary battery.

[0026] 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, the container 100 contains an electrode assembly 700, a pair of current collectors 500, and a pair of internal insulating members 400. An electrolyte solution (non-aqueous electrolyte) is sealed inside the container 100, but is not shown. There are no particular restrictions on the type of electrolyte solution, and various types can be selected as long as it does not impair the performance of the energy storage element 10. Furthermore, spacers, insulating films, and the like (not shown) may be disposed inside the container 100.

[0027] The container 100 is a rectangular parallelepiped (box-shaped) case. A rectangular parallelepiped here refers to a hexahedron with all faces formed into rectangles or squares. The container 100 has a container body 110 and a lid 120 that closes the opening of the container body 110. After the electrode assembly 700 is housed inside the container body 110, the container body 110 and the lid 120 are welded together or the like to seal the interior of the container 100. The materials of the container body 110 and the lid 120 are not particularly limited, but are preferably weldable metals such as stainless steel, aluminum, aluminum alloy, iron, and plated steel sheet.

[0028] The container body 110 is a rectangular cylindrical member with a bottom, and an opening formed at the top. The container body 110 has a pair of short side surfaces 112 on both sides in the X-axis direction, a pair of long side surfaces 113 on both sides in the Y-axis direction, and a bottom surface 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. The lid 120 is provided with a gas exhaust valve 122 that exhausts gas from inside the container 100 when the internal pressure of the container 100 increases excessively. The lid 120 may further be provided with a liquid injection port or the like for injecting an electrolyte into the container 100.

[0029] The electrode body 700 is an electricity storage element (power generation element) that includes a positive electrode plate, a negative electrode plate, and a separator 711 and is capable of storing electricity. The electrode body 700 includes an electrode body main body 710 and a pair of tab portions 720 provided at both ends of the electrode body main body 710 in the X-axis direction. Hereinafter, when distinguishing between the tab portions 720 of the positive electrode and the negative electrode, the tab portion 720 of the positive electrode will be referred to as tab portion 720A, and the tab portion 720 of the negative electrode will be referred to as tab portion 720B.

[0030] More specifically, the electrode assembly 700 is a wound electrode assembly formed by stacking a positive electrode plate and a negative electrode plate with a separator 711 interposed therebetween and winding the stack. In FIG. 2 , the two-dot chain line marked with the symbol W represents the winding axis W of the electrode assembly 700. The winding axis W is an imaginary axis that serves as the central axis when winding the positive electrode plate, etc. In the present embodiment, the winding axis W is parallel to the X-axis direction. The X-axis direction is an example of a first direction. The electrode assembly 700 is formed in a shape that is flat in a direction perpendicular to the winding axis W. In other words, the electrode assembly 700 is a wound and flat electrode assembly. In the present embodiment, the electrode assembly 700 has a shape that is flat in the Y-axis direction, as shown in FIG. 2 . The Y-axis direction is an example of a second direction.

[0031] More specifically, the electrode body 700 has curved portions at both ends in the Z-axis direction and an intermediate portion between these curved portions. In the intermediate portion, flat portions (portions substantially parallel to the XZ plane) of the electrode plates (positive and negative electrode plates) are stacked in the Y-axis direction. That is, in this embodiment, the main stacking direction of the electrode plates of the electrode body 700 is the Y-axis direction. Hereinafter, when referring to the "stacking direction of the electrode plates of the electrode body 700," this stacking direction refers to the Y-axis direction.

[0032] The positive electrode plate includes a positive electrode current collector foil, which is a long strip of metal foil, and a positive electrode active material layer formed on the surface of the positive electrode current collector foil. The negative electrode plate includes a negative electrode current collector foil, which is a long strip of metal foil, and a negative electrode active material layer formed on the surface of the negative electrode current collector foil. In the electrode body 700, the positive electrode active material layer of the positive electrode plate and the negative electrode active material layer of the negative electrode plate are stacked with a separator 711 interposed therebetween to form the electrode body main body 710. The separator 711 is wrapped around the outermost periphery of the electrode body main body 710 one or more times. The tabs of the positive electrode current collector foil are stacked in the Y-axis direction to form the tab portion 720A. The tabs of the negative electrode current collector foil are stacked in the Y-axis direction to form the tab portion 720B. The positive electrode current collector foil and the negative electrode current collector foil can be made of any known material that is stable to oxidation-reduction reactions during charge and discharge, such as nickel, iron, stainless steel, titanium, baked carbon, conductive polymers, conductive glass, Al—Cd alloy, etc. 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 can be made of any known material that is capable of absorbing and releasing charge transport ions.

[0033] In this embodiment, as shown in Fig. 2, the first conductive member 510 of the current collector 500 is joined to each of the pair of tab portions 720. Furthermore, each of the pair of tab portions 720 is folded in the stacking direction of the electrode plates of the electrode body 700 (the negative Y-axis direction in Fig. 2). The manner in which the tab portions 720 and the current collector 500 are connected will be described later with reference to Figs. 4 and 5.

[0034] The terminal 200 is a member electrically connected to the electrode assembly 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 assembly 700, and the other of the pair of terminals 200 is electrically connected to the negative electrode plate of the electrode assembly 700. The terminal 200 is attached to the lid 120 arranged above the electrode assembly 700. Specifically, the terminal 200 has a shaft portion 201 that penetrates the lid 120. The shaft portion 201 of the terminal 200 is inserted into and crimped into the through-hole 301 of the external insulating member 300, the through-hole 123 of the lid 120, the through-hole 401 of the internal insulating member 400, and the through-hole 523 of the current collector 500. In this way, the terminal 200 is fixed to the lid 120 together with the external insulating member 300, the internal insulating member 400, and the current collector 500. The terminal 200 is made 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 from the terminal 200. In this embodiment, the external insulating member 300 also functions as a gasket that seals the gap 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 from the current collector 500. The external insulating member 300 and the internal insulating member 400 are each formed from a resin material that has electrical insulation properties.

[0036] The current collector 500 is a member that electrically connects the tab portion 720 of the electrode body 700 and the terminal 200. More specifically, the current collector 500 includes a first conductive member 510 and a second conductive member 520. The first conductive member 510 is connected to the tab portion 720. The second conductive member 520 is connected to the first conductive member 510. The second conductive member 520 is further connected to the terminal 200. In other words, the second conductive member 520 electrically connects the first conductive member 510 and the terminal 200. As a result, the tab portion 720 of the electrode body 700 is electrically connected to the terminal 200 via the first conductive member 510 and the second conductive member 520. The configurations of the first conductive member 510 and the second conductive member 520 will be described later using FIGS. 4 and 5 .

[0037] When manufacturing the energy storage element 10 configured in this manner, the first conductive member 510 connected to the tab portion 720 of the electrode body 700 and the second conductive member 520 fixed to the lid body 120 are connected by, for example, laser welding. In this embodiment, the current collector 500 is configured to suppress the adverse effects of heat generated during this connection work on the electrode body main body 710. The configuration of the current collector 500 and its surroundings will be described below with further reference to Figures 3 and 4.

[0038] [2. Configuration of the current collector 500 and its periphery] Fig. 3 is a perspective view showing the configuration of the current collector 500 and its periphery according to the embodiment. In Fig. 3, members other than the current collector 500 and the electrode assembly 700, such as the container 100 provided in the energy storage element 10, are omitted from the illustration. Fig. 4 is a cross-sectional view showing the configuration of the current collector 500 and its periphery according to the embodiment. Fig. 4 is a cross-section of the energy storage element 10, and schematically shows a portion of a cross-section parallel to the XZ plane passing through line IV-IV in Fig. 1.

[0039] The energy storage element 10 according to this embodiment may include, for example, an insulating sheet or spacer between the electrode body main body 710 and the current collector 500, and between the current collector 500 and the inner surface 111 of the container 100 (see FIG. 4 ), but these are not shown in the drawing. The inner surface 111 of the container 100 is the surface behind the short side surface 112 of the container body 110. In this embodiment, the connecting pieces 525 of the first conductive member 510 and the second conductive member 520 are disposed between the electrode body main body 710 and the inner surface 111 of the container 100.

[0040] In energy storage element 10 according to the present embodiment, the connection mode between positive electrode tab portion 720A and current collector 500 is common to the connection mode between negative electrode tab portion 720B and current collector 500. Therefore, the following description focuses on the connection mode between tab portion 720, which is positive electrode tab portion 720A, and current collector 500.

[0041] 2 to 4 , in the present embodiment, the current collector 500 connecting the tab portion 720 and the terminal 200 is composed of a first conductive member 510 and a second conductive member 520. The tab portion 720 has a tab connection portion 721 bent in the Y-axis direction (the negative Y-axis direction in FIGS. 2 to 4 ). The first conductive member 510 has a first connection portion 511 connected to the tab connection portion 721 and a second connection portion 515 connected to the second conductive member 520. The second conductive member 520 has a connection plate portion 521 connected to the shaft portion 201 of the terminal 200, and a connection piece portion 525 extending from the connection plate portion 521 and connected to the second connection portion 515 of the first conductive member 510.

[0042] As described above, in the energy storage element 10 according to the present embodiment, the current collector 500 is composed of the first conductive member 510 and the second conductive member 520, which are separate members. Therefore, the tab portion 720 can be connected by ultrasonic bonding to the first conductive member 510 that is not connected to the second conductive member 520 fixed to the lid 120.

[0043] Specifically, the tab portion 720 can be connected to the first conductive member 510 with the entire tab portion 720 aligned parallel to the X-axis direction (see FIG. 2 ). Therefore, the tab portion 720 and the first connecting portion 511, which are stacked in the Y-axis direction, can be easily clamped, for example, with an ultrasonic horn and anvil. This allows the tab portion 720 and the first connecting portion 511 to be connected efficiently and / or accurately by ultrasonic bonding. In FIG. 4 , an example of the approximate range of the connection between the tab portion 720 and the first connecting portion 511 by ultrasonic bonding is schematically shown as a first connection range 550.

[0044] The method for connecting the tab portion 720 and the first conductive member 510 is not limited to ultrasonic bonding. Various methods such as crimping, laser welding, or resistance welding may be used to connect the tab portion 720 and the first conductive member 510.

[0045] Furthermore, the tab portion 720 connected to the first conductive member 510 is bent so that the first conductive member 510 is positioned between the tab portion 720 and the electrode body main body 710 in the X-axis direction. As a result, a tab connection portion 721 bent in the Y-axis direction is formed in the tab portion 720. In this state, the second connection portion 515 of the first conductive member 510 and the connection piece portion 525 of the second conductive member 520 are connected. As a result, when the electrode body 700 connected to the current collector 500 is housed in the container body 110, it is possible to shorten the distance between the electrode body main body 710 and the inner surface 111 of the container 100 that faces the electrode body main body 710 in the X-axis direction (see FIG. 4 ).

[0046] When connecting the second connecting portion 515 and the connecting piece 525, for example, as shown in FIG. 4 , the space between the overlapping portion of the second connecting portion 515 and the connecting piece 525 and the electrode body main body 710 is relatively narrow. Therefore, it is difficult to ultrasonically bond the overlapping portion by, for example, sandwiching it between an ultrasonic horn and an anvil. Therefore, laser welding, for example, is used to connect the second connecting portion 515 and the connecting piece 525. Specifically, the connecting piece 525 of the second conductive member 520 is overlapped on the second opposing surface 516 of the second connecting portion 515 facing the electrode body main body 710, and laser light is irradiated onto the outer surface 517 of the second connecting portion 515. This allows the second connecting portion 515 and the connecting piece 525 to be connected. In FIG. 4 , an example of the approximate location range of the connection portion (the portion that is melted and then solidified) between the second connecting portion 515 and the connecting piece 525 by laser welding is schematically shown as a second connection range 540.

[0047] As shown in FIG. 4 , the second connection portion 515 connected to the second conductive member 520 by laser welding is positioned farther from the electrode body main body 710 than the first connection portion 511. Therefore, heat generated by laser welding is less likely to adversely affect the electrode body main body 710. For example, the separators 711 disposed on the outermost periphery of the electrode body main body 710 and between the positive and negative electrode plates are less likely to be contracted or deformed by heat generated by laser welding. On the other hand, the first connection portion 511 connected to the tab portion 720 of the electrode body 700 is positioned inside the tab connection portion 721 of the tab portion 720 (the negative X-axis direction in FIG. 4 ), as shown in FIG. 4 . Therefore, the distance between the electrode body main body 710 and the inner surface 111 of the container 100 in the alignment direction of the electrode body main body 710 and the first connection portion 511 (the X-axis direction in this embodiment) can be relatively short.

[0048] As described above, the energy storage element 10 according to this embodiment includes an electrode assembly 700, a first conductive member 510, a second conductive member 520, and a container 100 that accommodates the electrode assembly 700, the first conductive member 510, and the second conductive member 520. The electrode assembly 700 includes an electrode assembly main body 710 and a tab portion 720 provided at one end of the electrode assembly main body 710 in the X-axis direction (the positive X-axis direction in FIG. 4 ). The tab portion 720 includes a tab connection portion 721 bent in the Y-axis direction that intersects the X-axis direction. The first conductive member 510 includes a first connection portion 511 connected to the tab connection portion 721 and a second connection portion 515 connected to the second conductive member 520. When viewed from the positive X-axis direction, the first connection portion 511 and the second connection portion 515 are aligned in the Z-axis direction that intersects the X-axis direction and the Y-axis direction. The second connection portion 515 is disposed in the positive X-axis direction relative to the first connection portion 511.

[0049] Thus, according to the energy storage element 10 of this embodiment, the second connection portion 515 is disposed in the positive direction of the X-axis relative to the first connection portion 511. In other words, the second connection portion 515 is disposed in a position farther from the electrode body main body 710 in the X-axis direction than the first connection portion 511. This makes it possible to suppress the adverse effects on the electrode body main body 710 of heat generated during the connection work (laser welding in this embodiment, the same applies below) between the second connection portion 515 and the second conductive member 520. In this way, the energy storage element 10 according to one aspect of the present invention is an energy storage element with improved quality.

[0050] In this embodiment, the first conductive member 510 includes a bent portion 519 between the first connecting portion 511 and the second connecting portion 515. Specifically, as shown in FIGS. 2 to 4 , the first conductive member 510 includes a plate-like portion that connects the first connecting portion 511 and the second connecting portion 515 and has a bent portion at each end in the Z-axis direction. That is, the first connecting portion 511 and the second connecting portion 515, both of which are parallel to the YZ plane and have a flat shape, are connected by the bent portion 519, which is parallel to the X-axis direction and has a portion tilted with respect to the Z-axis direction. As a result, the second connecting portion 515 is positioned in the positive direction of the X-axis relative to the first connecting portion 511. The bent portion 519 can also be described as bending in a direction away from the electrode body main body 710 as it approaches the second connecting portion 515 from the first connecting portion 511. This type of shape of the first conductive member 510 is called, for example, a crank shape.

[0051] According to this configuration, for example, by bending a plate-shaped metal material, it is possible to produce the first conductive member 510 having a shape in which the second connection portion 515 is disposed on one side of the first connection portion 511 in the X-axis direction. This makes it easy to produce the first conductive member 510. Furthermore, the positions of the first connection portion 511 and the second connection portion 515 can be changed as desired and can also be modified as appropriate. In other words, the degree of freedom in designing the first conductive member 510 is increased.

[0052] The positional relationship between the first connecting portion 511 and the second connecting portion 515 in this embodiment will be described more specifically as follows: The first connecting portion 511 has a first opposing surface 512 that faces the electrode body main body 710. The second connecting portion 515 has a second opposing surface 516 that faces the electrode body main body 710. The second opposing surface 516 is disposed on one side of the first opposing surface 512 in the X-axis direction (the positive X-axis direction in FIG. 4 ).

[0053] As described above, in the present embodiment, the second opposing surface 516 of the second connecting portion 515 is disposed at a position farther from the electrode body main body 710 in the X-axis direction than the first opposing surface 512 of the first connecting portion 511. In particular, the second opposing surface 516 is a surface that faces the electrode body main body 710, and there is a possibility that heat may adversely affect a certain area of ​​the electrode body main body 710. Therefore, it is possible to more reliably suppress the adverse effects that heat generated during the operation of connecting the second connecting portion 515 and the second conductive member 520 has on the electrode body main body 710.

[0054] More specifically, in this embodiment, the second opposing surface 516 of the second connecting portion 515 is disposed in the positive X-axis direction relative to the connecting surface 513 of the first connecting portion 511. The connecting surface 513 is the surface behind the first opposing surface 512 of the first connecting portion 511, and is the surface to which the tab connecting portion 721 is connected by ultrasonic bonding or the like. This allows the overlapping portion of the second connecting portion 515 and the second conductive member 520 to be located farther away from the electrode body main body 710. As a result, the adverse effects on the electrode body main body 710 of heat generated during the connection operation between the second connecting portion 515 and the second conductive member 520 can be more reliably suppressed. The second opposing surface 516 of the second connecting portion 515 may be disposed in the negative X-axis direction or in the positive X-axis direction relative to the connecting surface 513 of the first connecting portion 511. In either case, the second opposing surface 516 of the second connection portion 515 should be positioned in the positive direction of the X-axis (at a position farther from the electrode body main body 710) than the first opposing surface 512 of the first connection portion 511 in the X-axis direction.

[0055] In the present embodiment, the position of the outer surface 517 (see FIGS. 3 and 4 ), which is the surface of the second connection portion 515 opposite to the second opposing surface 516, will be explained as follows. The second connection portion 515 has the outer surface 517 facing in the positive direction of the X-axis. The first connection portion 511 is disposed between the tab connection portion 721 and the electrode body main body 710. The tab connection portion 721 has a tab side surface 722 facing in the positive direction of the X-axis. The outer surface 517 is disposed at the same position as the tab side surface 722 in the X-axis direction, or on the other side of the tab side surface 722 in the X-axis direction (the negative X-axis direction in FIG. 4 ).

[0056] In this way, the first connection portion 511 of the first conductive member 510 is disposed between the tab connection portion 721 and the electrode body main body 710, i.e., inside the tab connection portion 721. This allows the distance between the electrode body main body 710 and the inner surface 111 of the container 100 to be relatively short, thereby improving the occupancy rate of the electrode body main body 710 relative to the internal volume of the container 100. Furthermore, the outer surface 517 of the second connection portion 515 is disposed in the X-axis direction at the same position as the tab side surface 722 or at a position closer to the electrode body main body 710 than the tab side surface 722. In other words, the second connection portion 515 is disposed in a position away from the electrode body main body 710 in the X-axis direction and not protruding beyond the tab side surface 722. Therefore, an increase in the distance between the electrode body main body 710 and the inner surface 111 of the container 100 in the X-axis direction, which would be caused by the second connection portion 515 protruding beyond the tab side surface 722 in the positive X-axis direction, is suppressed. As a result, the occupancy rate of the electrode body main body 710 relative to the internal volume of the container 100 is prevented from decreasing.

[0057] The above describes the energy storage element 10 according to the embodiment. However, the energy storage element 10 may have a configuration different from that shown in Figures 1 to 4, and the energy storage element 10 may be used as an energy storage element provided in an energy storage device. Therefore, modifications of the energy storage element 10 will be described below, focusing on the differences from the above embodiment.

[0058] [3-1. Modification 1] Fig. 5 is a cross-sectional view showing a current collector 500a and its surrounding structure according to Modification 1 of the embodiment. Fig. 5 schematically shows a portion of a cross section of an energy storage element 10a according to this modification. The position of the cross section in Fig. 5 corresponds to the position of the cross section in Fig. 4.

[0059] The energy storage device 10a according to this modification includes an electrode body 700, a first conductive member 510a, a second conductive member 520, and a container 100. The first conductive member 510a includes a first connection portion 511 connected to a tab connection portion 721, and a second connection portion 515 connected to the second conductive member 520. When viewed from the positive direction of the X axis, the first connection portion 511 and the second connection portion 515 are aligned in the Z axis direction. The second connection portion 515 is disposed further in the positive direction of the X axis than the first connection portion 511. These configurations are common to the energy storage device 10 according to the embodiment.

[0060] In the energy storage device 10 according to the embodiment, the thickness in the X-axis direction of the second connection portion 515 is the same as the thickness in the X-axis direction of the first connection portion 511. In this modification, the thickness in the X-axis direction of at least a part of the second connection portion 515 is smaller than the thickness in the X-axis direction of the first connection portion 511. Specifically, the second connection portion 515 provided in the first conductive member 510a has a thin portion 518 that is thinner than the first connection portion 511, and the thin portion 518 and the second conductive member 520 are connected. In this respect, the energy storage device 10a according to the modification differs from the energy storage device 10 according to the embodiment.

[0061] In this way, because at least a portion of the second connecting portion 515 is provided on the first conductive member 510a as the thin-walled portion 518, the connection between the second connecting portion 515 and the second conductive member 520 is facilitated. Specifically, for example, the second connecting portion 515 and the second conductive member 520 can be connected by laser welding in a shorter time and / or with a smaller laser beam output. In other words, the connection is facilitated and adverse effects on the electrode body main body can be further suppressed. Furthermore, because the thin-walled portion 518 is connected to the connecting piece portion 525 of the second conductive member 520, the distance D1 between the connecting piece portion 525 and the electrode body main body 710 in the X-axis direction can be further increased, as shown in FIG. 5 . This further reliably suppresses adverse effects on the electrode body main body 710 caused by heat generated by laser welding.

[0062] 6 is a cross-sectional view showing a current collector 500b and its surrounding structure according to a second modification of the embodiment. Fig. 6 schematically shows a portion of a cross section of an energy storage element 10b according to this modification. The position of the cross section in Fig. 6 corresponds to the position of the cross section in Fig. 4.

[0063] Energy storage element 10b according to this modification has a configuration in common with energy storage element 10 according to the embodiment, and furthermore, like energy storage element 10a according to modification 1, the thickness in the X-axis direction of at least a part of second connection portion 515 is smaller than the thickness in the X-axis direction of first connection portion 511. Specifically, current collector 500b according to this modification includes first conductive member 510b, and second connection portion 515 included in first conductive member 510b has thin portion 518. Thin portion 518 is connected to second conductive member 520. In these respects, energy storage element 10b according to this modification is common with energy storage element 10a according to modification 1. This facilitates the process of connecting second connection portion 515 and second conductive member 520.

[0064] In this modified example, the thin-walled portion 518 and the second conductive member 520 are connected to each other, thereby increasing the distance D2 in the X-axis direction between the second connection portion 515 and the inner surface 111 of the container 100 without reducing the distance in the X-axis direction between the connection piece portion 525 and the electrode body main body 710. In this respect, this modified example differs from the energy storage element 10a according to modified example 1 (see FIG. 5 ). In this modified example, the relatively long distance D2 can more reliably insulate the second connection portion 515 from the inner surface 111 of the container 100 that faces the second connection portion 515 in the X-axis direction.

[0065] 7 is a plan view schematically illustrating the configuration of an energy storage device 900 including an energy storage element 10 according to an embodiment. As shown in FIG. 7, the energy storage element 10 may be used in the energy storage device 900. 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 900.

[0066] The energy storage device 900 shown in FIG. 7 includes a plurality of energy storage units 800 arranged therein. 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, and a bus bar (not shown) that electrically connects the plurality of energy storage units 800. 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 this case, the energy storage unit 800 may be referred to as a "energy storage device."

[0067] In this modified example, the energy storage device 900 includes one or more energy storage elements 10 according to the above embodiment, but the energy storage device 900 may include energy storage elements 10a or 10b according to modified example 1 or 2 above instead of or in addition to one or more energy storage elements 10.

[0068] [4. Other Modifications] Although the energy storage element according to the embodiment of the present invention and its modifications have been described above, the present invention is not limited to the embodiment and modifications. In other words, the embodiment disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is intended to include all modifications within the meaning and scope of the claims.

[0069] The electrode body 700 included in the energy storage element 10 may include only one of the pair of tab portions 720. For example, the electrode body 700 may include a positive electrode tab portion 720A at the end of the electrode body main body 710 in the positive direction of the X axis, and a bundle portion of negative electrode current collector foil (negative electrode bundling portion) exposed over the entire area of ​​the electrode body main body 710 in the Z axis direction at the end of the electrode body main body 710 in the negative direction of the X axis. In this case, the positive electrode tab portion 720A may be connected to the current collector 500 shown in Figures 2 to 4, and a current collector including a pair of legs that sandwich the negative electrode bundling portion in the Y axis direction may be connected to the negative electrode bundling portion.

[0070] The energy storage element 10 may include only one of the pair of terminals 200. For example, consider a case where the positive electrode plate of the electrode assembly 700 is electrically connected to the container 100, i.e., where the container 100 is used as a positive electrode terminal. In this case, only the current collector 500 of the pair of current collectors 500 that is connected to the negative electrode tab portion 720B may be included. Furthermore, in this case, the energy storage element 10 may include only one external insulating member 300 and one internal insulating member 400.

[0071] The second conductive member 520 does not have to be directly connected to the terminal 200. The second conductive member 520 may be electrically connected to the terminal 200, for example, via another conductive member connected to the shaft portion 201 of the terminal 200.

[0072] The first conductive member 510 does not necessarily have to include the bent portion 519. For example, the connection surface 513 of the first connecting portion 511 and the outer surface 517 of the second connecting portion 515 may form a continuous plane parallel to the YZ plane. Even in this case, the second opposing surface 516 can be positioned further to one side in the X-axis direction (e.g., the positive X-axis direction in FIG. 4 ) than the first opposing surface 512. This can suppress the adverse effects on the electrode body main body 710 of heat generated during the connection operation between the second connecting portion 515 and the second conductive member 520. In other words, the first conductive member 510 does not necessarily have to be a so-called crank-shaped member. The first conductive member 510 may be, for example, a single flat plate-shaped member, with the portion corresponding to the second connecting portion 515 formed thinner than the portion corresponding to the first connecting portion 511. Furthermore, a straight-shaped connecting portion extending in the Z-axis direction may be used to replace the bent portion 519. For example, when viewed from the Z-axis direction, if a part of the first connecting portion 511 and a part of the second connecting portion 515 are arranged at positions where they overlap each other, the part of the first connecting portion 511 and the part of the second connecting portion 515 can be connected by a straight connecting portion that extends in the Z-axis direction. Even in this case, the second opposing surface 516 can be arranged on one side of the first opposing surface 512 in the X-axis direction (for example, the positive X-axis direction in FIG. 4).

[0073] It is not essential that the energy storage element 10 includes a wound electrode body 700. The energy storage element 10 may include a laminated (stacked) electrode body formed by stacking a plurality of flat electrode plates, or an accordion-shaped electrode body in which the electrode plates are folded in an accordion-like shape. In either case, the electrode body included in the energy storage element 10 may include an electrode body main body and a tab portion provided at one end of the electrode body main body in the first direction (in the embodiment, the positive X-axis direction).

[0074] The number of tab portions 720 connected to the first connection portion 511 of the first conductive member 510 may be two or more. For example, if two tab portions 720A aligned in the Z-axis direction are provided at the end of the electrode body main body 710 in the positive X-axis direction, the two tab portions 720A may be connected to the first connection portion 511 by a predetermined method such as ultrasonic bonding.

[0075] The second conductive member 520 of the current collector 500 is fixed to the container 100 and electrically connected to the terminal 200 by crimping the shaft portion 201 of the terminal 200, but this is not essential. For example, the second conductive member 520 may have a shaft portion protruding in the positive direction of the Z axis, and the shaft portion may penetrate the terminal 200, which does not have the shaft portion 201, and be crimped on the surface of the terminal 200 facing the positive direction of the Z axis. Even in this case, the second conductive member 520 is fixed to the container 100 and electrically connected to the terminal 200. The method of joining the second conductive member 520 and the terminal 200 is not limited to crimping. The second conductive member 520 and the terminal 200 may be joined by welding, press-fitting, or screw joining (joining by fitting a male thread and a female thread).

[0076] It is not essential that the first connection portion 511 connected to the tab portion 720 of the electrode body 700 be disposed inside (in the negative X-axis direction in FIG. 4 ) the tab connection portion 721 of the tab portion 720. In other words, the first connection portion 511 may be disposed outside (in the positive X-axis direction in FIG. 4 ) the tab connection portion 721.

[0077] The thickness in the X-axis direction of the second connection portion 515 of the first conductive member 510 is set to be the same as the thickness in the X-axis direction of the first connection portion 511 of the first conductive member 510, but the thickness in the X-axis direction of the second connection portion 515 may be greater than the thickness in the X-axis direction of the first connection portion 511.

[0078] It is not essential that the second opposing surface 516 of the second connection portion 515 be arranged in a position facing the electrode body main body 710. The second opposing surface 516 may be arranged to face the space in the positive Z-axis direction relative to the electrode body main body 710. In other words, a first conductive member 510 may be employed in which the first connection portion 511 faces the electrode body main body 710 and the second connection portion 511 does not face the electrode body main body 710.

[0079] It is not essential that the outer surface 517 of the second connection portion 515 be disposed in the same position as the tab side surface 722 in the X-axis direction or in a position closer to the electrode body main body 710 than the tab side surface 722. In other words, the outer surface 517 of the second connection portion 515 may be disposed in a position farther from the electrode body main body 710 in the X-axis direction than the tab side surface 722.

[0080] The supplementary notes regarding the energy storage device 10 according to the above embodiment may also be applied to the energy storage devices 10a and 10b according to the 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.

[0081] The present invention can be applied to an electric storage element such as a lithium ion secondary battery.

[0082] 10, 10a, 10b Energy storage element 100 Container 200 Terminal 500, 500a, 500b Current collector 510, 510a, 510b First conductive member 511 First connection portion 512 First opposing surface 513 Connection surface 515 Second connection portion 516 Second opposing surface 517 Outer surface 518 Thin portion 519 Bent portion 520 Second conductive member 521 Connection plate portion 525 Connection piece portion 700 Electrode body 710 Electrode body main body 711 Separator 720, 720A, 720B Tab portion 721 Tab connection portion 722 Tab side surface

Claims

1. An energy storage element comprising: an electrode body, a first conductive member, and a second conductive member; the electrode body comprising an electrode body main body and a tab portion provided at one end of the electrode body main body in a first direction; the tab portion comprising a tab connection portion bent in a second direction intersecting the first direction; the first conductive member comprising a first connection portion connected to the tab connection portion and a second connection portion connected to the second conductive member; when viewed from one side of the first direction, the first connection portion and the second connection portion are aligned in a third direction intersecting the first direction and the second direction; and the second connection portion is positioned further towards the one side of the first direction than the first connection portion.

2. The energy storage device according to claim 1, wherein the first conductive member has a bent portion between the first connection portion and the second connection portion.

3. The energy storage element according to claim 1 or 2, wherein the thickness in the first direction of at least a part of the second connection portion is smaller than the thickness in the first direction of the first connection portion.

4. A storage element as described in claim 1 or 2, wherein the first connection portion has a first opposing surface facing the electrode body main body, the second connection portion has a second opposing surface facing the electrode body main body, and the second opposing surface is positioned on one side of the first direction relative to the first opposing surface.

5. A storage element as described in claim 1 or 2, wherein the second connection portion has an outer surface facing one side of the first direction, the first connection portion is arranged between the tab connection portion and the electrode body main body, the tab connection portion has a tab side surface facing one side of the first direction, and the outer surface is arranged in the same position as the tab side surface in the first direction or on the other side of the first direction than the tab side surface.

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