Power storage element

Abstract

A power storage element according to the present invention comprises a terminal, an electrode body, and a current collector that is connected to the terminal and the electrode body. The electrode body comprises a body part and a first tab part and a second tab part that protrude from the body part in a second direction that intersects a first direction that is the direction in which the terminal and the electrode body are aligned. The current collector comprises a connection part that is provided in the second direction of the body part and is connected to the first tab part and the second tab part. The first tab part and the second tab part are provided at different positions in the first direction and are joined to a first surface of the connection part.

Description

Energy storage element

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

[0002] Patent Document 1 discloses a battery in which a current collecting tab protrudes outward in the horizontal direction from the electrode group, and the lead has a top plate portion to which a terminal is connected and a leg portion that bends relative to the top plate portion in the height direction toward the side where the electrode group is located, and on the outer surface of the leg, the leg edge surfaces on both sides in the depth direction are joined to the current collecting tab.

[0003] Japanese Patent Application Laid-Open No. 2021-197294

[0004] In the conventional battery disclosed in Patent Document 1, the current collecting tabs of the electrode group are joined to the edge surfaces of the legs of the leads on both sides in the depth direction, which increases the width in the depth direction. A space-saving configuration is desired for the conventional battery.

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

[0006] A storage element according to one embodiment of the present invention comprises a terminal, an electrode body, and a current collector connected to the terminal and the electrode body, wherein the electrode body comprises a main body portion and a first tab portion and a second tab portion protruding from the main body portion in a second direction intersecting a first direction in which the terminal and the electrode body are arranged, the current collector is arranged in the second direction of the main body portion, and comprises a connection portion to which the first tab portion and the second tab portion are connected, the first tab portion and the second tab portion being joined to a first surface of the connection portion and being arranged at different positions in the first direction.

[0007] According to the energy storage device of the present invention, space can be saved.

[0008] FIG. 1 is a perspective view showing the appearance of an energy storage element according to an embodiment. FIG. 2 is a perspective view showing the internal configuration of a container of an energy storage element according to an embodiment, with a container body separated from the container. FIG. 3 is a perspective view of the internal configuration of a container of an energy storage element according to an embodiment, as viewed from the opposite side of FIG. 2. FIG. 4 is an exploded perspective view showing components of an energy storage element according to an embodiment, other than the container body, disassembled. FIG. 5 is a front view showing the arrangement of tab portions (first tab portion and second tab portion) of an electrode assembly according to an embodiment. FIG. 6 is a cross-sectional view showing the arrangement of tab portions (first tab portion and second tab portion) of an electrode assembly according to an embodiment. FIG. 7 is a schematic diagram showing the tab portions (first tab portion and second tab portion) of an electrode assembly according to an embodiment and an electrode assembly connection portion of a current collector. FIG. 8 is a schematic diagram showing the tab portions (first tab portion and second tab portion) of an electrode assembly according to an embodiment and an electrode assembly connection portion of a current collector. FIG. 9 is a plan view showing an example of an energy storage device according to an embodiment.

[0009] (1) An energy storage element according to one aspect of the present invention comprises a terminal, an electrode body, and a current collector connected to the terminal and the electrode body, the electrode body comprising a main body portion and a first tab portion and a second tab portion protruding from the main body portion in a second direction intersecting a first direction in which the terminal and the electrode body are arranged, the current collector being arranged in the second direction of the main body portion and comprising a connection portion to which the first tab portion and the second tab portion are connected, the first tab portion and the second tab portion being joined to a first surface of the connection portion and being arranged at different positions in the first direction.

[0010] In an energy storage element according to one aspect of the present invention, the first tab portion and the second tab portion of the electrode assembly are joined to a first surface of the connection portion of the current collector and are positioned at different positions in the first direction. By joining the first tab portion and the second tab portion to different positions on the first surface (one side) of the connection portion in this way, the width can be made smaller than if the first tab portion and the second tab portion were joined to both sides of the connection portion, thereby enabling space savings.

[0011] (2) In the energy storage element described in (1) above, the first tab portion and the second tab portion may be arranged in positions where they do not overlap in the first direction.

[0012] According to the energy storage element described in (2) above, the first tab portion and the second tab portion of the electrode body are arranged in positions where they do not overlap in the first direction, thereby further saving space.

[0013] (3) In the energy storage element described in (1) or (2) above, the first tab portion and the second tab portion may be joined to the first surface in the second direction.

[0014] According to the energy storage element described in (3) above, the first tab portion and the second tab portion of the electrode body are joined to the first surface of the connection portion of the current collector in the second direction, thereby enabling space saving in the second direction.

[0015] (4) In the energy storage device described in (3) above, the first surface may be a surface of the connection portion opposite to a second surface that faces the main body portion in the second direction.

[0016] According to the energy storage element described in (4) above, the first surface of the connection portion of the current collector is the surface (outer surface) opposite to the second surface facing the main body portion of the electrode body in the second direction of the connection portion, and therefore the first tab portion and the second tab portion are joined to the outer surface of the connection portion, which makes it easier to press the first tab portion and the second tab portion against the connection portion when joining them by laser welding or the like, and thus makes it easier to join the first tab portion and the second tab portion to the connection portion.

[0017] (5) In the energy storage element described in any one of (1) to (4) above, the first tab portion and the second tab portion may be arranged in overlapping positions when viewed from the first direction.

[0018] According to the energy storage element described in (5) above, the first tab portion and the second tab portion of the electrode body are arranged in overlapping positions when viewed from the first direction, which allows the lengths of the first tab portion and the second tab portion to be increased, thereby ensuring a larger bonding area between the first tab portion and the second tab portion and the connection portion of the current collector.

[0019] (6) In the energy storage element described in any one of (1) to (5) above, the electrode body may include a first electrode body and a second electrode body, the first electrode body may include the first tab portion, and the second electrode body may include the second tab portion.

[0020] According to the energy storage element described in (6) above, even when the electrode body comprises a first electrode body and a second electrode body, the first electrode body comprises a first tab portion and the second electrode body comprises a second tab portion, thereby enabling the first electrode body and the second electrode body to be joined to the current collector while saving space.

[0021] Hereinafter, with reference to the drawings, an energy storage element according to an embodiment of the present invention (including its modified examples) will be described. The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples only and are not intended to limit the present invention. In each drawing, dimensions and the like are not strictly illustrated. In each drawing, the same or similar components are designated by the same reference numerals.

[0022] In the following description and drawings, the X-axis direction is defined as the direction in which a pair of short sides of the container of one energy storage element face each other, the direction in which the short sides of the container of the energy storage element face each other, the arrangement direction of a pair of terminals (positive and negative electrodes) of the energy storage element, the arrangement direction of a pair of current collectors (positive and negative electrodes), the direction in which the electrode assembly connection portions of the current collectors face each other, the thickness direction of the electrode assembly connection portions, the winding axis direction of the electrode assembly, or the longitudinal direction of the electrode assembly. The Y-axis direction is defined as the thickness direction of the container (the direction in which the width of the electrode assembly is narrowest), the direction in which a pair of long sides of the container of one energy storage element face each other, the direction in which the long sides of the container face each other, the arrangement direction of two electrode assemblies, or the thickness direction of one electrode assembly (the direction in which the width of the electrode assembly is narrowest). The Z-axis direction is defined as the arrangement direction of the container body and lid of the container, the arrangement direction of the electrode assembly and terminals, the direction in which the terminals protrude from the container, the direction in which the terminal connection portions of the current collectors face each other, the thickness direction of the terminal connection portions, or the up-and-down direction. The X-axis, Y-axis, and Z-axis directions intersect with each other (orthogonal in this embodiment). Depending on the mode of use, the Z-axis direction may not be the up-down direction, but for the sake of convenience, the following description will be given assuming that the Z-axis direction is the up-down direction.

[0023] In the following description, the positive X-axis direction refers to the direction of the X-axis arrow, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. Simply referring to the X-axis direction refers to both or either of the positive X-axis direction and the negative X-axis direction. The same applies to the Y-axis and Z-axis directions. Hereinafter, the Z-axis direction will also be referred to as the first direction, the X-axis direction as the second direction, and the Y-axis direction as the third direction. Expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the directions or attitudes are not strictly the same. Two directions being parallel (or perpendicular) not only means that the two directions are completely parallel (or perpendicular), but also means that the two directions are substantially parallel (or perpendicular), i.e., there is a difference of, for example, a few percent. In the following description, the term "insulating" means "electrically insulating." An insulating material has a volume resistivity of 1×10 ６ Ωm or more, more preferably 1×10 ７ Ωm or more, more preferably 1×10 １０It is preferable that the material be made of a material with a resistance of Ωm or more.

[0024] (Embodiment) [1. Description of the Configuration of Energy Storage Element 10] First, the configuration of the energy storage element 10 according to the present embodiment will be described in detail with reference to Figs. 1 to 4. Fig. 1 is a perspective view showing the appearance of the energy storage element 10 according to the present embodiment. Fig. 2 is a perspective view showing the internal configuration of the container 100 of the energy storage element 10 according to the present embodiment, with the container body 110 separated from the container 100. Fig. 3 is a perspective view showing the internal configuration of the container 100 in the energy storage element 10 according to the present embodiment, as viewed from the opposite side of Fig. 2 in the X-axis direction. Fig. 4 is an exploded perspective view showing the components of the energy storage element 10 according to the present embodiment, other than the container body 110.

[0025] The energy storage element 10 is a secondary battery (single cell) capable of charging and discharging electricity, 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 moving 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 an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicle. Examples of the electric railway vehicle include a train, a monorail, a linear motor car, and a hybrid train 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.

[0026] The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than a non-aqueous electrolyte secondary battery, or may be a capacitor. The energy storage element 10 may be a primary battery instead of a secondary battery. The energy storage element 10 may be a battery using a solid electrolyte. The energy storage element 10 may be a pouch-type energy storage element. In the present embodiment, the energy storage element 10 is illustrated as having a rectangular parallelepiped shape (square) that is flattened in the Y-axis direction, but the shape of the energy storage element 10 is not limited to a rectangular parallelepiped shape, and may be a polygonal prism shape other than a rectangular parallelepiped, an elongated cylinder shape, an elliptical cylinder shape, a cylindrical shape, or the like.

[0027] As shown in FIG. 1 , the energy storage element 10 includes a container 100 and a pair of (positive and negative) terminals 200. As shown in FIGS. 2 to 4 , the energy storage element 10 further includes an electrode assembly 300 and a pair of (positive and negative) current collectors 400, which are housed inside the container 100. The energy storage element 10 also includes a pair of (positive and negative) gaskets disposed between the container 100 and the terminals 200 and between the container 100 and the current collectors 400, but these are not shown. An electrolyte solution (nonaqueous electrolyte) is sealed inside the container 100, but this is not shown. There are no particular limitations on the type of electrolyte solution, and various types can be selected as long as they do not impair the performance of the energy storage element 10. In addition to the above components, the energy storage device 10 may also include spacers arranged on the sides or below the electrode body 300, an insulating film that wraps the electrode body 300, and the like.

[0028] [1.1 Description of Container 100] The container 100 is a rectangular parallelepiped (square or box-shaped) case that includes a container body 110 with an opening that opens in the positive direction of the Z axis, and a lid 120 that closes the opening of the container body 110. The container body 110 is a rectangular cylindrical member with a bottom that forms the main body of the container 100. The lid 120 is a member that forms the lid of the container 100, and is disposed in the positive direction of the Z axis of the container body 110. The lid 120 is a flat, rectangular wall that extends in the X axis direction.

[0029] The container body 110 has a pair of long side walls 111 on both sides in the Y-axis direction (long sides), a pair of short side walls 112 on both sides in the X-axis direction (short sides), and a bottom wall 113 on the surface in the negative Z-axis direction (bottom surface) (see FIG. 2 ). The long side walls 111 are flat, rectangular walls extending in the X-axis direction. The long side walls 111 are adjacent to the short side walls 112, the bottom wall 113, and the lid 120. The area of ​​the long side walls 111 is larger than the area of ​​the short side walls 112. The short side walls 112 are flat, rectangular walls extending in the Z-axis direction. The bottom wall 113 is a flat, rectangular wall extending in the X-axis direction. The short side walls 112 are adjacent to the long side walls 111, the bottom wall 113, and the lid 120. The area of ​​the short side wall portion 112 is smaller than the area of ​​the long side wall portion 111. The bottom wall portion 113 is disposed adjacent to the long side wall portion 111 and the short side wall portion 112. Depending on the shape of the container 100, the long side wall portion 111 may be longer in the Z-axis direction, the short side wall portion 112 may be longer in the Y-axis direction, and the bottom wall portion 113 may be longer in the Y-axis direction.

[0030] After the electrode assembly 300 and other components are housed inside the container body 110, the container body 110 and the lid 120 are joined by welding or the like, thereby sealing the interior of the container 100. The material of the container 100 (the container body 110 and the lid 120) is not particularly limited and may be a weldable (joinable) metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet, or a resin. The container 100 may be formed of a laminate film or the like composed of multiple layers including a metal layer and a resin layer. The container body 110 and the lid 120 may be formed of the same material or different materials. The container 100 (the lid 120, etc.) may be provided with a liquid injection section for injecting an electrolyte into the container 100 during the manufacture of the energy storage device 10, and a gas exhaust valve for releasing pressure inside the container 100 if the pressure inside the container 100 increases excessively.

[0031] [1.2 Description of Terminal 200] The terminal 200 is an electrode terminal (positive electrode terminal and negative electrode terminal) electrically connected to the electrode assembly 300 via the current collector 400. The terminal 200 is a metal member that draws electricity stored in the electrode assembly 300 to the external space of the energy storage element 10 and introduces electricity into the internal space of the energy storage element 10 to store electricity in the electrode assembly 300. The terminal 200 is formed of a conductive member such as a metal, such as aluminum, an aluminum alloy, copper, or a copper alloy. The terminal 200 is connected (joined) to the current collector 400 by crimping, welding, or the like, and is attached to the lid 120. The terminal 200 is arranged alongside the electrode assembly 300 in the Z-axis direction (first direction). The terminal 200 is arranged in a state where it protrudes in the positive Z-axis direction from the outer surface (the surface in the positive Z-axis direction) of the lid 120. In this embodiment, terminal 200 is a welding terminal that is joined to an external conductive member such as a bus bar by welding, but terminal 200 may also be a bolt terminal that has a bolt portion formed with a male thread portion that protrudes in the positive direction of the Z axis and is joined to the conductive member by a bolt connection.

[0032] In this embodiment, two terminals 200 (a positive terminal 200 and a negative terminal 200) are arranged side by side in the X-axis direction. Hereinafter, one of the two terminals 200 (the terminal 200 located in the positive direction of the X-axis) will be referred to as terminal 210, and the other (the terminal 200 located in the negative direction of the X-axis) will be referred to as terminal 220. In this embodiment, terminal 210 is the positive terminal 200 (positive terminal), and terminal 220 is the negative terminal 200 (negative terminal).

[0033] [1.3 Description of the Electrode Assembly 300] The electrode assembly 300 is an electricity storage element (power generation element) formed by stacking positive and negative electrode plates and a separator. The electrode assembly 300 is a wound electrode assembly formed by winding the positive and negative electrode plates and a separator around a winding axis extending in the X-axis direction. The winding axis is an imaginary axis that serves as the central axis when winding the positive and negative electrode plates, etc. In this embodiment, it is a straight line that passes through the center of the electrode assembly 300 and is parallel to the X-axis direction. In this embodiment, the electrode assembly 300 has an elongated shape extending in the X-axis direction and has a substantially oval cylindrical shape (an oval shape when viewed in the X-axis direction). The shape of the electrode assembly 300 is not particularly limited and may be a substantially cylindrical shape or a substantially elliptical cylindrical shape, and the length of the electrode assembly 300 in the X-axis direction is also not particularly limited. The electrode assembly 300 may be elongated in the Z-axis direction.

[0034] The positive electrode plate is an electrode plate (electrode plate) in which a positive electrode active material layer is formed on the surface of a positive electrode current collector foil (metal foil) in the form of a long strip made of a metal such as aluminum or an aluminum alloy. The negative electrode plate is an electrode plate (electrode plate) in which a negative electrode active material layer is formed on the surface of a negative electrode current collector foil (metal foil) in the form of a long strip made of a metal such as copper or a copper alloy. For the positive electrode current collector foil and the negative electrode current collector foil, any known material can be used as long as it is stable against oxidation-reduction reactions during charge and discharge, such as nickel, iron, stainless steel, titanium, baked carbon, conductive polymers, conductive glass, and Al—Cd alloys. 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 any known material as long as it is capable of absorbing and releasing charge-transport ions.

[0035] As a positive electrode active material, LiMPO ４ , LiMSiO ４ , LiMBO ３ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), polyanion compounds such as lithium titanate, LiMn ２ O ４ or LiMn １．５ Ni ０．５ O ４ Spinel-type lithium manganese oxides such as LiMO ２(M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.) and the like can be used.

[0036] The negative electrode active material may be lithium metal, lithium alloys (lithium-silicon, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and lithium metal-containing alloys such as Wood's alloy), alloys capable of absorbing and releasing lithium, carbon materials (graphite, non-graphitizable carbon, easily graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), silicon oxides, metal oxides, lithium metal oxides (Li ４ Ti ５ O １２ etc.), polyphosphate compounds, or Co, commonly called conversion anodes ３ O ４ or Fe ２ Examples of the metal include compounds of transition metals such as P and elements of Groups 14 to 16.

[0037] The separator is a microporous insulating sheet made of resin or the like. Any known material can be used as the separator material as long as it does not impair the performance of the energy storage element 10. Examples of the separator include woven fabric, nonwoven fabric, and porous resin film.

[0038] The positive electrode plate has multiple tabs (positive electrode tabs) protruding to one side in the X-axis direction, and by winding the positive electrode plate, a positive electrode tab portion is formed in which the multiple tabs (positive electrode tabs) overlap. The negative electrode plate has multiple tabs (negative electrode tabs) protruding to the other side in the X-axis direction, and by winding the negative electrode plate, a negative electrode tab portion is formed in which the multiple tabs (negative electrode tabs) overlap. As a result, the electrode body 300 is configured to include an electrode body main body 310, a tab portion 320 protruding from the electrode body main body 310 in the positive direction of the X-axis, and a tab portion 330 protruding from the electrode body main body 310 in the negative direction of the X-axis.

[0039] The electrode body main body 310 is the main body of the electrode body 300 and is an elongated cylindrical portion formed by winding the portions of the positive and negative electrode plates other than the tabs and the separator. The tab portions 320 and 330 are portions that extend (protrude) outward from part of the edge of the electrode body main body 310 in the X-axis direction. The tab portions 320 and 330 protrude from the electrode body main body 310 in the X-axis direction (second direction) that intersects with the Z-axis direction (first direction) in which the terminal 200 and the electrode body 300 are aligned. In this embodiment, the tab portion 320 is a tab portion of a positive electrode formed by stacking and bundling positive electrode tabs, and the tab portion 330 is a tab portion of a negative electrode formed by stacking and bundling negative electrode tabs.

[0040] In this embodiment, the electrode body 300 includes a first electrode body 301 and a second electrode body 302 aligned in the Y-axis direction (a third direction intersecting the first and second directions). Both the first electrode body 301 and the second electrode body 302 are wound electrode bodies formed by winding a positive electrode plate, a negative electrode plate, and a separator. Therefore, the first electrode body 301 includes a first electrode body main body 311 and first tab portions 321 and 331 protruding from the first electrode body main body 311 in the X-axis direction (second direction) (see FIGS. 2 and 4 , etc.). The first tab portion 321 protrudes in the positive X-axis direction from a portion of the edge of the first electrode body main body 311 in the positive X-axis direction, and the first tab portion 331 protrudes in the negative X-axis direction from a portion of the edge of the first electrode body main body 311 in the negative X-axis direction. In this embodiment, the first tab portions 321 and 331 protrude outward from half of the first electrode body main body portion 311 in the negative Y-axis direction.

[0041] Similarly, the second electrode body 302 is configured to include a second electrode body main body portion 312 and second tab portions 322 and 332 that protrude from the second electrode body main body portion 312 in the X-axis direction (second direction) (see FIG. 3 , etc.). The second tab portion 322 protrudes in the positive X-axis direction from a part of the edge of the second electrode body main body portion 312 that is in the positive X-axis direction, and the second tab portion 332 protrudes in the negative X-axis direction from a part of the edge of the second electrode body main body portion 312 that is in the negative X-axis direction. In this embodiment, the second tab portions 322 and 332 protrude outward from half of the second electrode body main body portion 312 in the positive Y-axis direction.

[0042] The first tab portion 321 and the second tab portion 322 are tab portions of the positive electrode, and the first tab portion 331 and the second tab portion 332 are tab portions of the negative electrode. The tab portion 320 (first tab portion 321 and second tab portion 322) is connected (joined) to an electrode assembly connection portion 412 of a current collector 410 described below. The tab portion 330 (first tab portion 331 and second tab portion 332) is connected (joined) to an electrode assembly connection portion 422 of a current collector 420 described below. A more detailed description of the tab portion 320 (first tab portion 321 and second tab portion 322) and the tab portion 330 (first tab portion 331 and second tab portion 332) will be given later.

[0043] [1.4 Description of the Current Collector 400] The current collectors 400 are conductive current collecting members (positive electrode current collector and negative electrode current collector) that are arranged on both sides of the electrode body 300 in the X-axis direction and are connected (joined) to the terminal 200 and the electrode body 300 to electrically connect the terminal 200 and the electrode body 300. The current collector 400 has a shape in which a single plate-like member is bent, and is an L-shaped (inverted L-shaped) member when viewed from the Y-axis direction. The current collector 400 has a simple configuration and is easy to manufacture. Because the current collector 400 can be formed from a single plate-like member, there is no need to provide a separate lead, etc., and the number of parts can be reduced. Furthermore, by reducing the space occupied by the current collector 400 (space saving), the capacity of the energy storage element 10 can be increased.

[0044] In this embodiment, two current collectors 400 (positive electrode current collector 400 and negative electrode current collector 400) are arranged side by side in the X-axis direction. Hereinafter, one of the two current collectors 400 (current collector 400 located in the positive direction of the X-axis) will be referred to as current collector 410, and the other (current collector 400 located in the negative direction of the X-axis) will be referred to as current collector 420. In this embodiment, current collector 410 is the positive electrode current collector 400 (positive electrode current collector), and current collector 420 is the negative electrode current collector 400 (negative electrode current collector). Like the positive electrode current collector foil of the electrode assembly 300, current collector 410 (positive electrode current collector) is made of aluminum, an aluminum alloy, or the like. Like the negative electrode current collector foil of the electrode assembly 300, current collector 420 (negative electrode current collector) is made of copper, a copper alloy, or the like.

[0045] As shown in FIG. 4 , the current collector 410 includes a terminal connection portion 411 and an electrode assembly connection portion 412. The terminal connection portion 411 is a plate-shaped portion whose large surface faces the Z-axis direction (first direction) (along a direction perpendicular to the first direction), and the electrode assembly connection portion 412 is a plate-shaped portion whose large surface faces the X-axis direction (second direction) (along a direction perpendicular to the second direction). The terminal connection portion 411 is a flat, rectangular portion parallel to the XY plane and is connected (joined) to the terminal 200 (210). The terminal connection portion 411 is arranged along the lid 120 and includes a through-hole 401 through which the shank 201 of the terminal 210 passes. The shank 201 is a rivet portion of the terminal 210 that extends in the negative Z-axis direction. The shaft portion 201 is inserted into the through-hole 121 of the lid 120 and the through-hole 401 of the terminal connection portion 411, and then crimped. As a result, the current collector 410 is fixed to the lid 120 together with the terminal 210. The method for connecting (joining) the current collector 410 and the terminal 210 is not limited to crimping, and welding such as ultrasonic welding, laser welding, or resistance welding, or mechanical joining other than crimping, such as screw joining, may also be used.

[0046] The electrode assembly connection portion 412 is a flat, rectangular portion parallel to the YZ plane, and is connected (joined) to the electrode assembly 300. The electrode assembly connection portion 412 is arranged in the X-axis direction (second direction) of the electrode assembly main body portion 310 (the first electrode assembly main body portion 311 and the second electrode assembly main body portion 312). The electrode assembly connection portion 412 extends in the Z-axis negative direction from the end of the terminal connection portion 411 in the X-axis positive direction along the short side wall portion 112 of the container body 110 in the X-axis positive direction. As a result, the terminal connection portion 411 and the electrode assembly connection portion 412 are arranged in orientations facing different directions, and the electrode assembly connection portion 412 is arranged in an orientation facing the electrode assembly main body portion 310 (the first electrode assembly main body portion 311 and the second electrode assembly main body portion 312). The electrode assembly connection portion 412 is connected (joined) to the tab portion 320 of the electrode assembly 300. Specifically, the electrode assembly connection portion 412 is connected (joined) to the first tab portion 321 of the first electrode assembly 301 and the second tab portion 322 of the second electrode assembly 302. The electrode assembly connection portion 412 is an example of a connection portion where the first tab portion 321 and the second tab portion 322 are connected. In the present embodiment, the electrode assembly connection portion 412 and the tab portion 320 (the first tab portion 321 and the second tab portion 322) are joined by laser welding. The electrode assembly connection portion 412 and the tab portion 320 may be connected (joined) by welding such as ultrasonic welding or resistance welding, or by mechanical joining such as crimping or screw joining.

[0047] Specifically, the tab portion 320 is bent toward the current collector 410, positioned outside the current collector 410, and joined to the current collector 410. The tab portion 320 is bent toward the current collector 410, and joined to the surface opposite the surface facing the electrode body main body portion 310. In other words, the first tab portion 321 is bent toward the electrode body connection portion 412 in the positive Y-axis direction, positioned in the positive X-axis direction of the electrode body connection portion 412, and joined to the electrode body connection portion 412. The second tab portion 322 is bent toward the electrode body connection portion 412 in the negative Y-axis direction, positioned in the positive X-axis direction of the electrode body connection portion 412, and joined to the electrode body connection portion 412. In this way, the tab portion 320 (first tab portion 321 and second tab portion 322) is joined to the outside of the current collector 410 (electrode body connection portion 412) by wrapping around from both sides of the current collector 410 (electrode body connection portion 412) in the Y-axis direction.

[0048] Like the current collector 410, the current collector 420 includes a terminal connection portion 421 and an electrode assembly connection portion 422. The terminal connection portion 421 is a plate-shaped portion whose large surface faces the Z-axis direction (first direction) (along a direction perpendicular to the first direction), and the electrode assembly connection portion 422 is a plate-shaped portion whose large surface faces the X-axis direction (second direction) (along a direction perpendicular to the second direction). The terminal connection portion 421 is a flat, rectangular portion parallel to the XY plane and is connected (joined) to the terminal 200 (220). The terminal connection portion 421 is disposed along the lid 120 and includes a through-hole 401 through which the shaft portion 201 of the terminal 220 passes. The configuration in which the terminal connection portion 421 is joined to the terminal 220 is similar to the configuration in which the terminal connection portion 411 is joined to the terminal 210, and therefore a detailed description thereof will be omitted.

[0049] The electrode assembly connection portion 422 is a flat, rectangular portion parallel to the YZ plane, and is connected (joined) to the electrode assembly 300. The electrode assembly connection portion 422 is arranged in the X-axis direction (second direction) of the electrode assembly main body portion 310 (the first electrode assembly main body portion 311 and the second electrode assembly main body portion 312). The electrode assembly connection portion 422 extends in the Z-axis negative direction from the end of the terminal connection portion 421 in the X-axis negative direction along the short side wall portion 112 of the container body 110 in the X-axis negative direction. As a result, the terminal connection portion 421 and the electrode assembly connection portion 422 are arranged in orientations facing different directions, and the electrode assembly connection portion 422 is arranged in an orientation facing the electrode assembly main body portion 310 (the first electrode assembly main body portion 311 and the second electrode assembly main body portion 312). The electrode assembly connection portion 422 is connected (joined) to the tab portion 330 of the electrode assembly 300. Specifically, the electrode assembly connection portion 422 is connected (joined) to the first tab portion 331 of the first electrode assembly 301 and the second tab portion 332 of the second electrode assembly 302. The electrode assembly connection portion 422 is an example of a connection portion to which the first tab portion 331 and the second tab portion 332 are connected. The configuration in which the electrode assembly connection portion 422 and the tab portion 330 (the first tab portion 331 and the second tab portion 332) are joined is similar to the configuration in which the electrode assembly connection portion 412 and the tab portion 320 (the first tab portion 321 and the second tab portion 322) are joined, and therefore a detailed description thereof will be omitted.

[0050] Specifically, the tab portion 330 is bent toward the current collector 420, positioned outside the current collector 420, and joined to the current collector 420. The tab portion 330 is bent toward the current collector 420 and joined to the surface opposite the surface facing the electrode body main body portion 310. In other words, the first tab portion 331 is bent toward the electrode body connection portion 422 in the positive Y-axis direction, positioned in the negative X-axis direction of the electrode body connection portion 422, and joined to the electrode body connection portion 422. The second tab portion 332 is bent toward the negative Y-axis direction, positioned in the negative X-axis direction of the electrode body connection portion 422, and joined to the electrode body connection portion 422. In this way, the tab portion 330 (first tab portion 331 and second tab portion 332) is joined to the outside of the current collector 420 (electrode body connection portion 422) by wrapping around both sides of the current collector 420 (electrode body connection portion 422) in the Y-axis direction.

[0051] [2 Detailed Description of Tab Portion 320 and Tab Portion 330] Next, the tab portion 320 (first tab portion 321 and second tab portion 322) and the tab portion 330 (first tab portion 331 and second tab portion 332) of the electrode assembly 300 will be described in more detail with reference to FIGS. 5 to 8 . FIG. 5 is a front view showing the arrangement of the tab portion 320 (first tab portion 321 and second tab portion 322) and the tab portion 330 (first tab portion 331 and second tab portion 332) of the electrode assembly 300 according to the present embodiment. FIG. 6 is a cross-sectional view showing the arrangement of the tab portion 320 (first tab portion 321 and second tab portion 322) of the electrode assembly 300 according to the present embodiment. FIG. 6 is a view of the configuration of FIG. 5 cut along a plane parallel to the YZ plane including line VI-VI, as viewed from the positive direction of the X-axis. 7 and 8 are schematic diagrams showing the tab portion 320 (first tab portion 321 and second tab portion 322) of the electrode assembly 300 and the electrode assembly connection portion 412 of the current collector 410 according to the present embodiment. FIGS. 7 and 8 are schematic diagrams showing the configuration of FIG. 6 cut along a plane parallel to the XY plane including line VII-VII, as viewed from the negative Z-axis direction. In FIGS. 6 to 8 , the tab portion 320 (first tab portion 321 and second tab portion 322) and its surrounding configuration are similar to the tab portion 330 (first tab portion 331 and second tab portion 332) and its surrounding configuration, and therefore the tab portion 330 and its surrounding configuration are not shown.

[0052] As described above and shown in FIGS. 5 and 6 , the first tab portion 321 of the first electrode body 301 and the second tab portion 322 of the second electrode body 302 are joined to a first surface 412a of the electrode body connection portion 412 (connection portion) of the current collector 410. In other words, the surface of the electrode body connection portion 412 to which the first tab portion 321 is joined is the same as the surface of the electrode body connection portion 412 to which the second tab portion 322 is joined. The first tab portion 321 and the second tab portion 322 are joined to the first surface 412a in the X-axis direction (second direction). In other words, the first tab portion 321 and the second tab portion 322 are joined to the surface of the electrode body connection portion 412 in the X-axis direction. The first surface 412a is the surface of the electrode assembly connecting portion 412 (connecting portion) opposite to the second surface 412b that faces the electrode assembly main body portion 310 (the first electrode assembly main body portion 311 and the second electrode assembly main body portion 312) in the X-axis direction (second direction). In other words, as shown in FIGS. 4 to 6 , if the surface of the electrode assembly connecting portion 412 that faces the electrode assembly main body portion 310 is the second surface 412b, the first surface 412a is the surface opposite to the second surface 412b of the electrode assembly main body portion 310. Specifically, the first surface 412a is the surface of the electrode assembly connecting portion 412 facing the positive X-axis direction, and the second surface 412b is the surface of the electrode assembly connecting portion 412 facing the negative X-axis direction. The first tab portion 321 and the second tab portion 322 are joined to the surface (outer surface) of the electrode assembly connecting portion 412 facing the positive X-axis direction.

[0053] The first tab portion 321 and the second tab portion 322 are disposed at different positions in the Z-axis direction (first direction). That is, the first tab portion 321 and the second tab portion 322 are disposed offset in the Z-axis direction. The first tab portion 321 and the second tab portion 322 are disposed at positions where they do not overlap in the Z-axis direction (first direction). In the present embodiment, the first tab portion 321 is disposed in the negative Z-axis direction relative to the second tab portion 322. Specifically, the first tab portion 321 and the second tab portion 322 are disposed spaced apart in the Z-axis direction. The first tab portion 321 and the second tab portion 322 may be disposed so as not to overlap in the Z-axis direction, with the edge of the first tab portion 321 in the positive Z-axis direction and the edge of the second tab portion 322 in the negative Z-axis direction in contact in the Z-axis direction.

[0054] The first tab portion 321 and the second tab portion 322 are positioned so as to overlap when viewed from the Z-axis direction (first direction). In other words, because the length of at least one of the first tab portion 321 and the second tab portion 322 in the Y-axis direction is longer, the tip end of the first tab portion 321 in the positive Y-axis direction is positioned further in the positive Y-axis direction than the tip end of the second tab portion 322 in the negative Y-axis direction. As a result, the first tab portion 321 and the second tab portion 322 have portions that overlap when viewed from the Z-axis direction. This will be described in detail below. In the following description, it is assumed that the lengths (protrusion amounts) of the tabs provided on the first tab portion 321 and the second tab portion 322 are all the same. Even when the tab lengths are made different, a larger bonding area can be ensured between the first tab portion 321 and the second tab portion 322 and the electrode assembly connection portion 412 of the current collector 410. However, there are problems such as, for example, the need to provide a large portion of the electrode plate without an active material layer to form long tabs, which reduces cost benefits; variations in tab length cause the tabs to flap, which creates manufacturing problems; and limitations (limits) on adjusting the tab positions by making the tab lengths different. For this reason, adopting the configuration of this embodiment has many advantages over making the tab lengths different. Even when the tab lengths are made different and the configuration of this embodiment is adopted, a larger bonding area can be ensured between the first tab portion 321 and the second tab portion 322 and the electrode assembly connection portion 412 of the current collector 410.

[0055] As shown in FIGS. 7 and 8 , the tab of the first tab portion 321 located furthest in the negative Y-axis direction (outer side) is referred to as the first tab 321a, and the tab located furthest in the positive Y-axis direction (inner side) is referred to as the first tab 321b. The tab of the second tab portion 322 located furthest in the positive Y-axis direction (outer side) is referred to as the second tab 322a, and the tab located furthest in the negative Y-axis direction (inner side) is referred to as the second tab 322b. The thickness of each of the first electrode body main body 311 of the first electrode body 301 and the second electrode body main body 312 of the second electrode body 302 is referred to as the electrode body thickness t, and the width of the electrode body connection portion 412 of the current collector 410 in the Y-axis direction is referred to as the current collector width b. In this case, as shown in FIG. 7 , if the current collector width b is large (greater than approximately 1.5 times the electrode body thickness t), the first tab 321a protrudes in the Y-axis direction more than the first tab 321b. 8, when the current collector width b is small (less than about 1.5 times the electrode body thickness t), the first tab 321b protrudes in the Y-axis direction more than the first tab 321a. The same applies to the second tabs 322a and 322b.

[0056] As a result, at least one of the first tabs 321a and 321b is positioned to protrude in the positive Y-axis direction from the center position of the electrode body connection portion 412 in the Y-axis direction. At least one of the second tabs 322a and 322b is also positioned to protrude in the negative Y-axis direction from the center position of the electrode body connection portion 412 in the Y-axis direction. As a result, at least one of the first tabs 321a and 321b and at least one of the second tabs 322a and 322b overlap when viewed in the Z-axis direction. In Figures 7 and 8, for ease of explanation, the first tab portion 321 and the second tab portion 322 are illustrated as overlapping in the X-axis direction, but as described above, the first tab portion 321 and the second tab portion 322 are positioned so that they do not overlap in the Z-axis direction and do not overlap in the X-axis direction.

[0057] When the electrode body thickness t is small, the current collector width b may also be small, but when the current collector width b is small, the first tab portion 321 and the second tab portion 322 are likely to be positioned so as to overlap when viewed from the Z-axis direction in order to ensure a joining area between the first tab portion 321 and the second tab portion 322 and the electrode body connection portion 412. Thus, whether the first tab portion 321 and the second tab portion 322 are positioned so as to overlap when viewed from the Z-axis direction depends on the electrode body thickness t and the current collector width b. The inventors of the present application have found that the first tab portion 321 and the second tab portion 322 are likely to be positioned so as to overlap when viewed from the Z-axis direction when the following numerical ranges are met: (1) Electrode body thickness t≦10 mm (2) Electrode body thickness t≦15 mm and current collector width b≦20 mm (3) Electrode body thickness t≦20 mm and current collector width b≦25 mm (4) Electrode body thickness t≦25 mm and current collector width b≦30 mm (5) Electrode body thickness t≦30 mm and current collector width b≦34 mm

[0058] Of the above (1) to (5), (2) to (4) are preferred. Energy storage elements 10 with sizes (2) to (4) are often manufactured, and in the above (2) to (4) sizes, tab handling is easier. In particular, when the tabs of the first tab portion 321 and the second tab portion 322 are the same length, tab handling becomes difficult in the above (1) and (5). Furthermore, as the length of the electrode body 300 in the X-axis direction increases, the tab position tends to shift, making it difficult to adjust the tab position depending on the tab length. The longer the length of the electrode plate in the winding direction, the greater the loss of the electrode plate when a malfunction occurs.

[0059] The first tab portion 331 of the first electrode body 301 and the second tab portion 332 of the second electrode body 302 also have the same configuration as the first tab portion 321 of the first electrode body 301 and the second tab portion 322 of the second electrode body 302. In other words, the first tab portion 331 and the second tab portion 332 are joined to a first surface 422a of the electrode body connection portion 422 (connection portion) of the current collector 420. The first tab portion 331 and the second tab portion 332 are joined to the first surface 422a in the X-axis direction (second direction). The first surface 422a is the surface of the electrode body connection portion 422 (connection portion) opposite to the second surface 422b that faces the electrode body main body portion 310 (the first electrode body main body portion 311 and the second electrode body main body portion 312) in the X-axis direction (second direction). The first surface 422a is the surface of the electrode body connection part 422 in the negative X-axis direction, and the second surface 422b is the surface of the electrode body connection part 422 in the positive X-axis direction. The first tab part 331 and the second tab part 332 are joined to the surface (outer surface) of the electrode body connection part 422 in the negative X-axis direction.

[0060] The first tab portion 331 and the second tab portion 332 are disposed at different positions in the Z-axis direction (first direction). The first tab portion 331 and the second tab portion 332 are disposed at positions where they do not overlap in the Z-axis direction (first direction). In this embodiment, the first tab portion 331 is disposed in the positive direction of the Z-axis relative to the second tab portion 332 (see FIGS. 3 and 5, etc.).

[0061] That is, in the first electrode body 301, the first tab portion 321 protrudes from a portion of the first electrode body main body 311 in the negative Z-axis direction, and the first tab portion 331 protrudes from a portion of the first electrode body main body 311 in the positive Z-axis direction. The first electrode body 301 maintains the same shape (a rotationally symmetric shape) even when rotated 180° about an axis passing through its center and parallel to the Y-axis direction. In the second electrode body 302, the second tab portion 322 protrudes from a portion of the second electrode body main body 312 in the positive Z-axis direction, and the second tab portion 332 protrudes from a portion of the second electrode body main body 312 in the negative Z-axis direction. The second electrode body 302 maintains the same shape (a rotationally symmetric shape) even when rotated 180° about an axis passing through its center and parallel to the Y-axis direction. Furthermore, the second electrode body 302 has the same shape as the first electrode body 301 rotated 180° about an axis (winding axis) that passes through its center and is parallel to the X-axis direction (a shape that is rotationally symmetrical to the first electrode body 301). For this reason, the second electrode body 302 can be obtained by producing two first electrode bodies 301 and rotating one of the first electrode bodies 301 upside down. This eliminates the need to produce electrode bodies with two different shapes, and only requires producing two electrode bodies with one type of shape, thereby improving manufacturing efficiency.

[0062] The first tab portion 331 and the second tab portion 332 are arranged in overlapping positions when viewed from the Z-axis direction (first direction). The specific configurations of the first tab portion 331 and the second tab portion 332 are similar to the configurations of the first tab portion 321 and the second tab portion 322 described with reference to Figures 7 and 8, etc.

[0063] [3 Description of Effects] As described above, according to the energy storage element 10 of the embodiment of the present invention, the first tab portion 321 and the second tab portion 322 of the electrode assembly 300 are joined to the first surface 412a of the electrode assembly connection portion 412 (connection portion) of the current collector 410, and are arranged at different positions in the Z-axis direction (first direction). By joining the first tab portion 321 and the second tab portion 322 to different positions on the first surface 412a (one side) of the electrode assembly connection portion 412 (connection portion) in this way, the width in the X-axis direction (second direction) can be made smaller than if the first tab portion 321 and the second tab portion 322 were joined to both sides of the electrode assembly connection portion 412 (connection portion). This allows the energy storage element 10 to save space.

[0064] By joining the first tab portion 321 and the second tab portion 322 to different positions on the first surface 412a of the electrode assembly connection portion 412, it is possible to prevent the first tab portion 321 and the second tab portion 322 from overlapping (stacking). This allows the thickness of the joining portion to be thin when joining the first tab portion 321 and the second tab portion 322 to the electrode assembly connection portion 412, making it easier to join the first tab portion 321 and the second tab portion 322 to the electrode assembly connection portion 412 and reducing joining defects. Since the joining area between the first tab portion 321 and the second tab portion 322 and the electrode assembly connection portion 412 can be increased, it is possible to improve the joining strength between the first tab portion 321 and the second tab portion 322 and the electrode assembly connection portion 412 and also to reduce heat generation when current flows.

[0065] By arranging the first tab portion 321 and the second tab portion 322 of the electrode assembly 300 in positions where they do not overlap in the Z-axis direction (first direction), further space savings can be achieved. Because the thickness of the joint portion can be further reduced when joining the first tab portion 321 and the second tab portion 322 to the electrode assembly connection portion 412, it becomes easier to join the first tab portion 321 and the second tab portion 322 to the electrode assembly connection portion 412, and joint defects can be further reduced. Because the joint area between the first tab portion 321 and the second tab portion 322 and the electrode assembly connection portion 412 can be further increased, joint strength can be further improved and heat generation when current flows can be further reduced.

[0066] By joining the first tab portion 321 and the second tab portion 322 of the electrode body 300 to the first surface 412a of the electrode body connection portion 412 (connection portion) of the current collector 410 in the X-axis direction (second direction), space can be saved in the X-axis direction (second direction).

[0067] The first surface 412a of the electrode assembly connection portion 412 (connection portion) of the current collector 410 is the surface (outer surface) opposite to the second surface 412b of the electrode assembly connection portion 412 (connection portion) that faces the electrode assembly main body portion 310 of the electrode assembly 300 in the X-axis direction (second direction). Therefore, the first tab portion 321 and the second tab portion 322 are joined to the outer surface of the electrode assembly connection portion 412 (connection portion). This makes it easier to press the first tab portion 321 and the second tab portion 322 against the electrode assembly connection portion 412 (connection portion) when joining by laser welding or the like, and therefore makes it easier to join the first tab portion 321 and the second tab portion 322 to the electrode assembly connection portion 412 (connection portion).

[0068] The first tab portion 321 and the second tab portion 322 of the electrode assembly 300 are positioned so as to overlap when viewed from the Z-axis direction (first direction). This allows the lengths of the first tab portion 321 and the second tab portion 322 to be increased, thereby ensuring a larger bonding area between the first tab portion 321 and the second tab portion 322 and the electrode assembly connection portion 412 (connection portion) of the current collector 410. Ensuring a larger bonding area reduces the resistance of the current path and facilitates the bonding work. Increasing the lengths of the first tab portion 321 and the second tab portion 322 makes it easier to handle the first tab portion 321 and the second tab portion 322 and allows the length of inner tabs (such as the second tab 321b shown in FIG. 7 ) to be increased.

[0069] Even when the electrode body 300 comprises a first electrode body 301 and a second electrode body 302, the first electrode body 301 comprises a first tab portion 321 and the second electrode body 302 comprises a second tab portion 322, thereby enabling the first electrode body 301 and the second electrode body 302 to be joined to the current collector 410 while saving space.

[0070] Although the effects of the tab portion 320 (first tab portion 321 and second tab portion 322) have been described above, the same applies to the effects of the tab portion 330 (first tab portion 331 and second tab portion 332).

[0071] The energy storage element 10 in the present embodiment may be used in an energy storage device. In this case, the technology of the present invention may be applied to at least one energy storage element 10 included in the energy storage device. FIG. 9 is a plan view showing an example of an energy storage device 12 according to the present embodiment. As shown in FIG. 9 , a plurality of energy storage units 11 are arranged inside the energy storage device 12. The energy storage unit 11 is composed of a plurality of electrically connected energy storage elements 10. The energy storage device 12 may include a bus bar (not shown) that electrically connects the plurality of energy storage elements 10, a bus bar (not shown) that electrically connects the plurality of energy storage units 11, and the like. The energy storage unit 11 or the energy storage device 12 may include a status monitoring device (not shown) that monitors the status of one or more energy storage elements 10. The energy storage device 12 may include only one energy storage unit 11. In other words, the energy storage unit 11 may be referred to as an energy storage device.

[0072] [4 Description of Modifications] While the energy storage device 10 according to the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. The embodiment disclosed herein is illustrative in all respects, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

[0073] In the above embodiment, the current collector 400 has a shape formed by bending a single plate-like member, but this is not limited to this. In the current collector 410, the terminal connection portion 411 may be a rod-like portion rather than a plate-like portion, and its shape is not particularly limited. The same applies to the electrode body connection portion 412. The same applies to the current collector 420.

[0074] In the above embodiment, the outer surface of the electrode assembly connection portion 412 of the current collector 410 in the X-axis direction is the first surface 412a, and the first tab portion 321 and the second tab portion 322 are joined to the first surface 412a. However, this is not limited to this. The inner surface of the electrode assembly connection portion 412 in the X-axis direction (the surface behind the outer surface, i.e., the surface facing the electrode assembly main body portion 310) may be the first surface, and the first tab portion 321 and the second tab portion 322 may be joined to this first surface. A surface of the electrode assembly connection portion 412 other than the X-axis direction, such as the Y-axis direction, may be the first surface, and the first tab portion 321 and the second tab portion 322 may be joined to this first surface. In other words, the tab portion 320 may be joined to the surface facing the electrode assembly main body portion 310 while being bent toward the current collector 410. Even in this case, space can be saved in the second direction. The same applies to the first tab portion 331 and the second tab portion 332.

[0075] In the above embodiment, the first tab portion 321 and the second tab portion 322 are bent from both sides of the electrode body connection portion 412 of the current collector 410 and joined to the electrode body connection portion 412, but they may also be bent from the same side of the electrode body connection portion 412 and joined to the electrode body connection portion 412.

[0076] In the above embodiment, the electrode assembly 300 includes the first electrode assembly 301 and the second electrode assembly 302, the first electrode assembly 301 includes the first tab portion 321, and the second electrode assembly 302 includes the second tab portion 322, but this is not limited to this. The electrode assembly 300 may include only one electrode assembly, and the one electrode assembly may include the first tab portion 321 and the second tab portion 322. The electrode assembly 300 may include three or more electrode assembly, and any of the three or more electrode assembly may include the first tab portion 321 and the second tab portion 322. The same applies to the first tab portion 331 and the second tab portion 332.

[0077] In the above embodiment, the first tab portion 321 is arranged in the negative Z-axis direction relative to the second tab portion 322, but it may also be arranged in the positive Z-axis direction relative to the second tab portion 322. The same applies to the first tab portion 331 and the second tab portion 332. In other words, both the first tab portions 321 and 331 may protrude from a portion of the first electrode body main portion 311 in the negative Z-axis direction, or may protrude from a portion of the first electrode body main portion 311 in the positive Z-axis direction. The same applies to the second tab portions 322 and 332.

[0078] In the above embodiment, the first tab portion 321 and the second tab portion 322 are arranged in positions where they do not completely overlap in the Z-axis direction, but they may also partially overlap. That is, the first tab portion 321 and the second tab portion 322 only need to be arranged in positions where they do not at least partially overlap in the Z-axis direction (different positions in the Z-axis direction). The more the first tab portion 321 and the second tab portion 322 do not overlap in the Z-axis direction, the more space can be saved in the X-axis direction. If they do not completely overlap in the Z-axis direction, even more space can be saved. The same applies to the first tab portion 331 and the second tab portion 332.

[0079] In the above embodiment, the first tab portion 321 and the second tab portion 322 are arranged in positions where they overlap when viewed from the Z-axis direction, but they may be arranged in positions where they do not overlap when viewed from the Z-axis direction. The same applies to the first tab portion 331 and the second tab portion 332.

[0080] In the above embodiment, the first tab portions 321 and 331 protrude outward from half of the first electrode body main body portion 311 in the negative Y-axis direction, but this is not limited to this. One or both of the first tab portions 321 and 331 may protrude outward from half of the first electrode body main body portion 311 in the positive Y-axis direction, or may protrude outward from the entire first electrode body main body portion 311 in the Y-axis direction. The same applies to the second tab portions 322 and 332.

[0081] In the above embodiment, one first tab portion 321 protrudes from the first electrode body main portion 311, but two or more first tab portions 321 may protrude. The same applies to the second tab portion 322. In this case, it is sufficient that at least one first tab portion 321 and at least one second tab portion 322 are disposed in different positions, but it is preferable that all of the first tab portions 321 and all of the second tab portions 322 are disposed in different positions. The same applies to the first tab portion 331 and the second tab portion 332.

[0082] In the above embodiment, the first tab portion 321 includes multiple tabs, but it may include only one tab. Alternatively, a lead connected to multiple tabs may be referred to as the first tab portion 321. The same applies to the second tab portion 322. The same applies to the first tab portion 331 and the second tab portion 332.

[0083] In the above embodiment, the electrode body 300 (first electrode body 301, second electrode body 302) is a wound electrode body whose winding axis is parallel to the lid body 120. However, the electrode body 300 may be a wound electrode body whose winding axis is perpendicular to the lid body 120. The electrode body 300 may be a laminated (stacked) electrode body formed by stacking a plurality of flat electrode plates, or may be a bellows-type electrode body in which electrode plates are folded in a bellows shape, or may be an electrode body of another form.

[0084] Any combination of the components included in the above-described embodiments and their modifications is also included within the scope of the present invention.

[0085] The present invention can be applied to an electric storage device such as a lithium ion secondary battery.

[0086] REFERENCE SIGNS LIST 10 Energy storage element 11 Energy storage unit 12 Energy storage device 100 Container 110 Container body 111 Long side wall portion 112 Short side wall portion 113 Bottom wall portion 120 Lid body 121, 401 Through hole 200, 210, 220 Terminal 201 Shaft portion 300 Electrode body 301 First electrode body 302 Second electrode body 310 Electrode body main body portion 311 First electrode body main body portion 312 Second electrode body main body portion 320, 330 Tab portion 321, 331 First tab portion 321a, 321b First tab 322, 332 Second tab portion 322a, 322b Second tab 400, 410, 420 Current collector 411, 421 Terminal connection portion 412, 422 Electrode body connection portion 412a, 422a First surface 412b, 422b Second surface

Claims

1. An energy storage element comprising: a terminal, an electrode body, and a current collector connected to the terminal and the electrode body; the electrode body comprising a main body portion and a first tab portion and a second tab portion protruding from the main body portion in a second direction intersecting a first direction in which the terminal and the electrode body are arranged; the current collector is arranged in the second direction of the main body portion and has a connection portion to which the first tab portion and the second tab portion are connected; and the first tab portion and the second tab portion are joined to a first surface of the connection portion and are arranged at different positions in the first direction.

2. The energy storage element according to claim 1, wherein the first tab portion and the second tab portion are positioned so as not to overlap in the first direction.

3. The energy storage element according to claim 1 or 2, wherein the first tab portion and the second tab portion are joined to the first surface in the second direction.

4. The energy storage element according to claim 3, wherein the first surface is a surface of the connection portion opposite to a second surface that faces the main body portion in the second direction.

5. The energy storage element according to claim 1 or 2, wherein the first tab portion and the second tab portion are arranged in overlapping positions when viewed from the first direction.

6. The energy storage element according to claim 1 or 2, wherein the electrode body comprises a first electrode body and a second electrode body, the first electrode body comprises the first tab portion, and the second electrode body comprises the second tab portion.

Images