Energy storage element

Abstract

To provide a power storage element capable of preventing an electrode body from being damaged.SOLUTION: A power storage element 10 includes an electrode body 700 that is formed by winding an electrode plate around a winding axis L extending in a first direction, and stacking a plurality of electrode plate parts 740a in a second direction. The plurality of electrode plate parts 740a include a first electrode part 741, a second electrode part 742 aligned with the first electrode part 741 in the second direction, and a third electrode plate part 743 between the first electrode part 741 and the second electrode part 742. The first electrode part 741 has a first tab 741a projecting from a first body part 741a. The second electrode part 742 has a second tab 742b projecting from a second body part 742a and overlapping the first tab 741a when viewed from the second direction. The third electrode plate part 743 has no tab between the first tab 741b and the second tab 742b, the first tab 741b and the second tab 742b being joined to a current collector 500 in a folded state.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an energy storage element including an electrode assembly and a current collector. [Background technology]

[0002] Conventionally, there has been known an energy storage element that includes an electrode body in which electrode plates are wound and stacked, and a current collector, and the tab of the electrode body is joined to the current collector. For example, Patent Document 1 discloses a lithium secondary battery (energy storage element) that has a configuration in which a current collecting tab (tab) of an internal electrode body (electrode body) in which positive and negative electrode plates are wound and stacked is joined to an internal terminal portion (current collector). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-7346 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described conventional energy storage element, there is a risk of damage to the electrode body. That is, in a configuration such as the above-described conventional energy storage element, the tabs of the electrode body are joined to the current collector in a stacked and folded state, and therefore the tabs are crowded together and compressed, which may damage the bases of the tabs, etc.

[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 suppress damage to an electrode body. [Means for solving the problem]

[0006] In order to achieve the above object, an energy storage element according to one aspect of the present invention is an energy storage element including an electrode body, an electrode terminal, and a current collector connecting either a positive electrode plate or a negative electrode plate of the electrode body to the electrode terminal, wherein the electrode body is formed by winding the electrode plate around a winding axis extending in a first direction, so that a plurality of electrode plate portions of the electrode plate are stacked in a second direction intersecting the first direction, and the plurality of electrode plate portions are formed by stacking a first electrode plate portion, a second electrode plate portion aligned with the first electrode plate portion in the second direction, and a second electrode plate portion aligned with the first electrode plate portion and a front electrode plate portion. and a third electrode plate portion arranged between the second electrode plate portions, wherein the first electrode plate portion has a first main body portion and a first tab protruding from the first main body portion, the second electrode plate portion has a second main body portion and a second tab protruding from the second main body portion and arranged at a position overlapping with the first tab when viewed from the second direction, and the third electrode plate portion has a third main body portion between the first main body portion and the second main body portion without having a tab between the first tab and the second tab, and the first tab and the second tab are joined to the current collector in a folded state.

[0007] According to this, in the electrode body of the energy storage element, the first tab of the first electrode plate portion and the second tab of the second electrode plate portion overlap when viewed from the second direction, and the third electrode plate portion does not have a tab between the first tab and the second tab, and the first tab and the second tab are joined to the current collector in a folded state. In this way, in the electrode body, no tab of the third electrode plate portion is provided between the first tab of the first electrode plate portion and the second tab of the second electrode plate portion, and the first tab and the second tab are joined to the current collector in a folded state. As a result, the first tab and the second tab are joined to the current collector, but no tab is disposed between the first tab and the second tab, thereby preventing the tabs from being crowded together. Therefore, even if multiple tabs (first tabs and second tabs) are joined to the current collector in a folded state, the tabs can be prevented from being crowded together and being damaged. In the present invention, the electrode body has an electrode body main body portion and a group of tabs protruding from a portion of the electrode body main body portion. In this specification, the first body portion is defined as a portion of the electrode body main body located at a position where the first tab protrudes and having the same width as the maximum tab width of the first tab. The second body portion is defined as a portion of the electrode body main body located at a position where the second tab protrudes and having the same width as the maximum tab width of the second tab. The third body portion is defined as a portion of the electrode body main body located between the first and second body portions and having the same width as either the first or second body portion.

[0008] The first electrode plate portion and the second electrode plate portion may be arranged at positions sandwiching the winding axis in the second direction.

[0009] According to this, by arranging the first and second electrode plate portions of the electrode body at positions sandwiching the winding axis, the first tab and the second tab are arranged at positions apart from each other, which makes it possible to prevent the tabs from being damaged due to being crowded together when the tabs (first tabs and second tabs) are joined to the current collector in the electrode body.

[0010] The first electrode plate portion and the second electrode plate portion may be electrode plate portions of different turns of the electrode plate, and the second electrode plate portion and the third electrode plate portion may be electrode plate portions of the same turn of the electrode plate.

[0011] According to this, by arranging the first and second electrode plate portions of the electrode assembly in different turns of the electrode plate, current can be collected from the current collector by the first tab in the turn where the first electrode plate portion is arranged, and current can be collected from the current collector by the second tab in the turn where the second electrode plate portion is arranged. By arranging the second and third electrode plate portions in the same turn of the electrode plate, current can be collected from the current collector by the second tab in the turn where the second electrode plate portion is arranged, even if a tab is not provided on the third electrode plate portion. In this way, even if the electrode assembly is configured to prevent damage due to the tabs being crowded together, current can be collected from the current collector efficiently, thereby preventing a decrease in current collection performance from the current collector. Note that when multiple first electrode plate portions and multiple second electrode plate portions are arranged, at least one first electrode plate portion and at least one second electrode plate portion of the multiple first electrode plate portions and multiple second electrode plate portions may be electrode plate portions in different turns. Similarly, when a plurality of second electrode plate portions and a plurality of third electrode plate portions are arranged, at least one second electrode plate portion and at least one third electrode plate portion among the plurality of second electrode plate portions and the plurality of third electrode plate portions may be electrode plate portions of the same circumference.

[0012] The plurality of electrode plate portions may include a plurality of the first electrode plate portions and a plurality of the second electrode plate portions aligned in the second direction, and a plurality of the third electrode plate portions arranged between the plurality of first electrode plate portions and the plurality of second electrode plate portions.

[0013] According to this, in the electrode assembly, a plurality of third electrode plate portions are disposed between a plurality of first electrode plate portions and a plurality of second electrode plate portions. This allows a plurality of first tabs of the plurality of first electrode plate portions and a plurality of second tabs of the plurality of second electrode plate portions to be bundled together and joined to a current collector, with a plurality of third electrode plate portions without tabs sandwiched between them. Therefore, in the electrode assembly, the plurality of first tabs and the plurality of second tabs can be easily joined to the current collector, making it easy to realize a configuration that prevents damage to the tabs due to crowding.

[0014] The plurality of electrode plate portions may have a plurality of first electrode plate portions adjacent to each other in the second direction, and the plurality of first tabs of the plurality of first electrode plate portions may be arranged in adjacent positions in the second direction.

[0015] According to this, in the electrode body, a plurality of first electrode plate portions are arranged adjacent to each other in the second direction, and a plurality of first tabs of the plurality of first electrode plate portions are arranged adjacent to each other in the second direction. This makes it possible to easily manufacture the energy storage element, thereby reducing manufacturing costs. Note that "arranged adjacent to each other in the second direction" means that the first electrode plate portions are arranged in positions where they at least partially overlap when viewed from the second direction.

[0016] The plurality of electrode plate portions may further include a fourth electrode plate portion arranged at a position where the second electrode plate portion is sandwiched between the third electrode plate portion, and the fourth electrode plate portion may have a fourth main body portion at a position where the second main body portion is sandwiched between the third main body portion and the fourth electrode plate portion, without having a tab at a position where the second tab is sandwiched between the first tab and the fourth electrode plate portion.

[0017] According to this, in the electrode assembly, a tab is not provided on the fourth electrode plate portion that sandwiches the second electrode plate portion with the third electrode plate portion. As a result, the first tab of the first electrode plate portion and the second tab of the second electrode plate portion are joined to the current collector, but no tab is arranged on the fourth electrode plate portion, so that the tabs joined to the current collector can be prevented from being crowded together. Therefore, even if multiple tabs (first tab and second tab) are joined to the current collector in a bent state in the electrode assembly, damage due to the crowded tabs can be prevented. Note that the fourth body portion is defined as a portion of the electrode assembly main body that is located at a position where the second body portion is sandwiched between the fourth electrode plate portion and the third electrode plate portion and has the same width as the first or second body portion.

[0018] The present invention can be realized not only as such an electricity storage element, but also as an electrode body or a combination of an electrode body and a current collector. [Effects of the Invention]

[0019] According to the energy storage device of the present invention, damage to the electrode assembly can be suppressed. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a perspective view showing the appearance of an energy storage element according to an embodiment; [Figure 2] FIG. 2 is an exploded perspective view showing the components of the energy storage device according to the embodiment. [Figure 3] FIG. 2 is a perspective view showing the configuration of an electrode body according to the embodiment. [Figure 4] FIG. 2 is a cross-sectional view showing the configuration of an electrode body according to an embodiment in a state where the electrode body is joined to a current collector. [Figure 5] FIG. 2 is a cross-sectional view showing the configuration of an electrode body according to an embodiment in a state where the electrode body is joined to a current collector. [Figure 6] FIG. 10 is a cross-sectional view showing the configuration of an electrode body according to a first modified example of the embodiment in a state where the electrode body is joined to a current collector. [Figure 7] FIG. 10 is a cross-sectional view showing a configuration in a state where an electrode body according to a second modification of the embodiment is joined to a current collector. [Figure 8] FIG. 10 is a cross-sectional view showing the configuration of an electrode body according to a third modification of the embodiment in a state where the electrode body is joined to a current collector. [Figure 9] FIG. 10 is a cross-sectional view showing the configuration of an electrode body according to a fourth modified example of the embodiment in a state where the electrode body is joined to a current collector. DETAILED DESCRIPTION OF THE INVENTION

[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 arrangement direction of a pair of electrode terminals (positive and negative, hereinafter the same) of an energy storage element, the arrangement direction of a pair of current collectors, or the opposing direction of the short side surfaces of a container. The Y-axis direction is defined as the stacking direction of multiple electrode plate parts of the electrode body, the opposing direction of the long side surfaces of the container, or the thickness direction of the container. The Z-axis direction is defined as the direction in which the winding axis of the electrode body extends, the arrangement direction of the electrode terminals, current collectors, and electrode body, the arrangement direction of the container body and lid of the container, or the up-down direction. The X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Note that depending on the usage mode, the Z-axis may not be the up-down direction; however, for convenience of explanation, the Z-axis direction will be described below as the up-down direction.

[0023] In the following description, for example, the positive X-axis direction refers to the direction of the X-axis arrow, and the negative X-axis direction refers to the opposite direction to the positive X-axis direction. The same applies to the Y-axis and Z-axis directions. In the following, the Z-axis direction may also be referred to as the first direction, and the Y-axis direction may also be referred to as the second direction. Furthermore, expressions indicating relative directions or attitudes, such as parallel and perpendicular, may also include cases where the directions or attitudes are not strictly those of the same kind. For example, saying that two directions are perpendicular does not only mean that the two directions are completely perpendicular, but also means that the directions are substantially perpendicular, i.e., there may be a difference of, for example, a few percent.

[0024] (Embodiment) [1 General Description of Energy Storage Element 10] First, an overall description will be given of an energy storage device 10 according to the present embodiment. Fig. 1 is a perspective view showing the appearance of an energy storage device 10 according to the present embodiment. Fig. 2 is an exploded perspective view showing each component of the energy storage device 10 according to the present embodiment.

[0025] The energy storage element 10 is a secondary battery (single cell) that can charge and discharge electricity, specifically a nonaqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is used for power storage or power supply applications. The energy storage element 10 is used, for example, 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, 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 gasoline-powered automobile. 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 use or a power generator.

[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 not be a secondary battery, but may be a primary battery that allows stored electricity to be used without the user having to charge it. The energy storage element 10 may be a battery that uses a solid electrolyte. The energy storage element 10 may also be a pouch-type energy storage element. In this embodiment, the energy storage element 10 is illustrated as having a flat rectangular parallelepiped (square) shape, but the shape of the energy storage element 10 is not limited to a rectangular parallelepiped shape, and may be a cylindrical shape, an elongated cylindrical shape, a polygonal prism shape other than a rectangular parallelepiped, or the like.

[0027] As shown in FIG. 1, the energy storage device 10 includes a container 100, a pair of electrode terminals 200 (positive and negative), and a pair of upper gaskets 300 (positive and negative). As shown in FIG. 2, the container 100 contains a pair of lower gaskets 400 (positive and negative), a pair of current collectors 500 (positive and negative), and an electrode assembly 700. An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but this is not shown. The type of electrolyte is not particularly limited as long as it does not impair the performance of the energy storage device 10, and various electrolytes can be selected. In addition to the above components, spacers disposed on the sides or below the electrode assembly 700, an insulating film enveloping the electrode assembly 700, and the like may also be disposed.

[0028] The container 100 is a rectangular parallelepiped (square or box-shaped) case having a container body 110 with an opening formed therein 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 constitutes the main body of the container 100. The container body 110 has a pair of flat, rectangular short side walls 111 on both side surfaces (short side surfaces) in the X-axis direction, a pair of flat, rectangular long side walls 112 on both side surfaces (long side surfaces) in the Y-axis direction, and a flat, rectangular bottom wall 113 on the negative Z-axis side. The lid 120 is a rectangular plate-like member that constitutes the lid of the container 100 and is disposed on the positive Z-axis side of the container body 110, extending in the X-axis direction. The lid 120 is provided with a gas exhaust valve 121 for releasing the pressure inside the container 100 when the pressure inside the container 100 increases, and a liquid injection part 122 for injecting the electrolyte into the container 100.

[0029] With this configuration, the container 100 is structured so that the inside is sealed by accommodating the electrode assembly 700 and the like inside the container body 110 and then joining the container body 110 and the lid body 120 by welding or the like. The material of the container 100 (container body 110 and lid body 120) is not particularly limited, and can be a weldable metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet, but resin can also be used.

[0030] The electrode assembly 700 is an electricity storage element (power generation element) that includes a positive electrode plate, a negative electrode plate, and a separator and can store electricity. Specifically, the electrode assembly 700 is formed by winding layers of positive and negative electrode plates with a separator sandwiched between them. As a result, multiple tabs of the positive electrode plates are stacked to form a positive electrode side tab group 720, and multiple tabs of the negative electrode plates are stacked to form a negative electrode side tab group 730. In other words, the electrode assembly 700 has an electrode assembly main body 710 and tab groups 720 and 730 that protrude from a portion of the electrode assembly main body 710 in the positive Z-axis direction and extend in the positive Y-axis direction. In this embodiment, the electrode assembly 700 has an oval shape when viewed in the Z-axis direction.

[0031] The electrode assembly 700 further includes fixing members 701 that fix the positive electrode plate, the negative electrode plate, and the separator. The fixing members 701 are arranged in a total of six locations, at the center in the X-axis direction and both ends of the electrode assembly 700 in the Z-axis direction, and are insulating tapes that sandwich and fix the positive electrode plate, the negative electrode plate, and the separator in the Y-axis direction. The arrangement position, number, material, etc. of the fixing members 701 are not particularly limited, and the positive electrode plate, the negative electrode plate, and the separator may be fixed using a method other than insulating tape. A detailed description of the configuration of the electrode assembly 700 will be given later.

[0032] The electrode terminals 200 are terminal members (positive electrode terminal and negative electrode terminal) electrically connected to the electrode body 700 via the current collector 500. In other words, the electrode terminals 200 are metal members that draw out electricity stored in the electrode body 700 to the external space of the energy storage element 10 and introduce electricity into the internal space of the energy storage element 10 to store electricity in the electrode body 700. The electrode terminals 200 are formed of a conductive member such as a metal, such as aluminum, an aluminum alloy, copper, or a copper alloy. The electrode terminals 200 are connected (joined) to the current collector 500 by crimping or the like, and are attached to the lid body 120.

[0033] Specifically, the electrode terminal 200 has a shaft portion 201 (rivet portion) extending downward (in the negative Z-axis direction). The shaft portion 201 is inserted into the through-hole 301 of the upper gasket 300, the through-hole 123 of the lid 120, the through-hole 401 of the lower gasket 400, and the through-hole 501 of the current collector 500, and is crimped. As a result, the electrode terminal 200, together with the upper gasket 300, the lower gasket 400, and the current collector 500, is fixed to the lid 120. Note that the method for connecting (joining) the electrode terminal 200 and the current collector 500 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 fastening, may also be used.

[0034] The current collectors 500 are rectangular, flat current collecting members (positive electrode current collector and negative electrode current collector) that electrically connect the electrode assembly 700 and the electrode terminal 200. The current collectors 500 connect either the positive electrode plate or the negative electrode plate of the electrode assembly 700 to the electrode terminal 200. Specifically, the positive electrode side current collector 500 is connected (joined) to the positive electrode side tab group 720 of the electrode assembly 700 by welding or the like, and is also joined to the positive electrode side electrode terminal 200 by crimping or the like, as described above. The same applies to the negative electrode side. The material of the current collectors 500 is not particularly limited, but for example, the positive electrode side current collector 500 is formed of a conductive material such as a metal such as aluminum or an aluminum alloy, and the negative electrode side current collector 500 is formed of a conductive material such as a metal such as copper or a copper alloy. The method for connecting (joining) the current collector 500 and the tab groups 720, 730 may be any welding method such as ultrasonic welding, laser welding, or resistance welding, or may be mechanical joining such as crimping or screw fastening.

[0035] The upper gasket 300 is a flat, insulating sealing member disposed between the lid 120 of the container 100 and the electrode terminal 200. The lower gasket 400 is a flat, insulating sealing member disposed between the lid 120 and the current collector 500. The upper gasket 300 and the lower gasket 400 are formed from an electrically insulating resin, such as polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), ABS resin, or a composite material thereof.

[0036] [2. Description of the configuration of the electrode body 700] Next, the configuration of the electrode assembly 700 will be described in detail. FIG. 3 is a perspective view showing the configuration of the electrode assembly 700 according to the present embodiment. Specifically, FIG. 3(a) shows the configuration of the electrode assembly 700 in a partially unfolded state when wound, and FIG. 3(b) shows an enlarged view of the electrode assembly 700 after winding. FIGS. 4 and 5 are cross-sectional views showing the configuration of the electrode assembly 700 according to the present embodiment in a state where it is joined to the current collector 500. Specifically, FIG. 4(a) is a cross-sectional view showing the configuration when the electrode assembly 700 is joined to the current collector 500 and before the positive electrode side tab group 720 is folded, cut along a plane parallel to the YZ plane at the position of the tab group 720, together with the lid 120, the electrode terminal 200, the upper gasket 300, and the lower gasket 400. FIG. 4(b) is a cross-sectional view showing the state after the tab group 720 in FIG. 4(a) has been folded. FIG. 5 is an enlarged cross-sectional view of (b) of FIG. 4, showing the configuration of the electrode assembly 700 in detail.

[0037] 3(a), the electrode assembly 700 is formed by alternately stacking and winding a positive electrode plate 740, a negative electrode plate 750, and separators 760a and 760b. That is, the electrode assembly 700 is formed by stacking and winding a positive electrode plate 740, a separator 760a, a negative electrode plate 750, and a separator 760b in this order.

[0038] The positive electrode plate 740 is an electrode plate in which a positive electrode active material layer is formed on the surface of a positive electrode substrate layer, which is a long strip of metal foil made of aluminum or an aluminum alloy. The negative electrode plate 750 is an electrode plate in which a negative electrode active material layer is formed on the surface of a negative electrode substrate layer, which is a long strip of metal foil made of copper or a copper alloy. For the positive electrode substrate layer and the negative electrode substrate layer, any known material that is stable against oxidation-reduction reactions during charge and discharge, such as nickel, iron, stainless steel, titanium, baked carbon, conductive polymers, conductive glass, or an Al-Cd alloy, can be used. 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 that is capable of absorbing and releasing lithium ions.

[0039] For example, the positive electrode active material may be a polyanion compound such as LiMPO4, LiMSiO4, or LiMBO3 (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), lithium titanate, LiMn2O4, or LiMn 1.5 Ni 0.5 Examples of the anode active material include spinel-type lithium manganese oxides such as LiTiO4, and lithium transition metal oxides such as LiMO2 (wherein M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.). Examples of the anode active material include lithium metal, lithium alloys (lithium-metal-containing alloys such as lithium-silicon, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and Wood's alloy), alloys capable of absorbing and releasing lithium, carbon materials (e.g., graphite, non-graphitizable carbon, easily graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), silicon oxides, metal oxides, and lithium metal oxides (Li4Ti5O 12 and the like), polyphosphate compounds, or compounds of transition metals and elements of Groups 14 to 16, such as Co3O4 and Fe2P, which are generally called conversion negative electrodes.

[0040] Separators 760a and 760b are microporous sheets made of resin. Any known material can be used as the material for separators 760a and 760b as long as it does not impair the performance of energy storage device 10. For example, separators 760a and 760b can be made of woven fabric or nonwoven fabric that is insoluble in organic solvents, or a synthetic resin microporous film made of a polyolefin resin such as polyethylene.

[0041] The positive electrode plate 740 has, at one end (the end in the positive Z-axis direction) in the direction in which the winding axis L extends (hereinafter also referred to as the winding axis direction), a plurality of rectangular first tabs 741b and a plurality of rectangular second tabs 742b that protrude outward (in the positive Z-axis direction). The plurality of first tabs 741b and the plurality of second tabs 742b are arranged in a stacked state in the Y-axis direction. Similarly, the negative electrode plate 750 has, at one end (the end in the positive Z-axis direction) in the winding axis direction, a plurality of rectangular first tabs 751b and a plurality of rectangular second tabs 752b that protrude outward (in the positive Z-axis direction). The plurality of first tabs 751b and the plurality of second tabs 752b are also arranged in a stacked state in the Y-axis direction. These first tabs 741b, 751b and second tabs 742b, 752b are portions where no active material layer is formed and the base material layer is exposed. The shapes of first tabs 741b, 751b and second tabs 742b, 752b are not particularly limited. Winding axis L is an imaginary axis that serves as the central axis when winding positive electrode plate 740, negative electrode plate 750, etc., and in this embodiment, is a straight line that passes through the center of electrode body 700 and is parallel to the Z-axis direction.

[0042] Then, as shown in FIG. 3B, the stacked first tabs 741b and second tabs 742b are bundled together to form tab group 720, which extends and protrudes in the positive direction of the Z axis. Similarly, the stacked first tabs 751b and second tabs 752b are bundled together to form tab group 730, which extends and protrudes in the positive direction of the Z axis. Then, as shown in FIG. 4A, the tab groups 720 and 730 are joined to the surface of the current collector 500 facing each other in the Y axis direction, which faces the Y axis. Thereafter, as shown in FIG. 4B, the tab groups 720 and 730 are bent together with the current collector 500 in the positive direction of the Y axis. Note that the fixing member 701 is not shown in FIG. 3B, and the separators 760a and 760b are not shown in FIGS. 4A and 4B (and FIG. 5). Furthermore, in (a) and (b) of FIG. 4 (and FIG. 5), the configuration on the tab group 720 side is illustrated.

[0043] The electrode body main body 710 is a portion that constitutes the main body of the electrode body 700, and specifically, is the portion of the electrode body 700 other than the tab groups 720 and 730. In other words, the electrode body main body 710 is an elongated cylindrical portion formed by winding together the portions of the positive electrode plate 740 and the negative electrode plate 750 on which the active material layers are formed and the separators 760a and 760b. As a result, the electrode body main body 710 has a pair of electrode body curved portions 711 and 712 on both sides in the X-axis direction, and a pair of electrode body flat portions 713 and 714 on both sides in the Y-axis direction.

[0044] The electrode body curved portion 711 is a curved portion that is curved in a semicircular arc shape so as to protrude in the negative X-axis direction when viewed from the Z-axis direction, and is arranged opposite the short side wall portion 111 of the container body 110 in the negative X-axis direction. The electrode body curved portion 712 is a curved portion that is curved in a semicircular arc shape so as to protrude in the positive X-axis direction when viewed from the Z-axis direction, and is arranged opposite the short side wall portion 111 of the container body 110 in the positive X-axis direction. In other words, the electrode body curved portions 711 and 712 are curved portions that protrude in the X-axis direction toward the short side wall portion 111 when viewed from the Z-axis direction. The electrode body flat portion 713 is a rectangular, flat portion that extends parallel to the XZ plane facing the negative Y-axis direction, and is arranged opposite the long side wall portion 112 of the container body 110 in the negative Y-axis direction. The electrode body flat portion 714 is a rectangular, flat portion extending parallel to the XZ plane facing the positive Y-axis direction, and is disposed opposite the long side wall portion 112 of the container body 110 facing in the positive Y-axis direction.

[0045] In this configuration, the first tabs 741b and 751b protrude from the electrode assembly flat portion 713, and the second tabs 742b and 752b protrude from the electrode assembly flat portion 714. Specifically, the multiple first tabs 741b and 751b protrude from approximately half of the electrode assembly flat portion 713 in the negative Y-axis direction, and the multiple second tabs 742b and 752b protrude from approximately half of the electrode assembly flat portion 714 in the negative Y-axis direction.

[0046] Here, the plurality of first tabs 741b and the plurality of second tabs 742b have the same configuration as the plurality of first tabs 751b and the plurality of second tabs 752b. In other words, the positive electrode plate 740 and the negative electrode plate 750 have the same configuration. For this reason, hereinafter, the configuration of the positive electrode plate 740 (first tab 741b, second tab 742b, etc.) will be described in detail, and a description of the configuration of the negative electrode plate 750 (first tab 751b, second tab 752b, etc.) will be simplified or omitted.

[0047] As shown in FIGS. 3 and 5, the portion of the electrode assembly flat portion 713 from which the first tab 741b protrudes is referred to as the first main body portion 741a, and the portion of the electrode assembly flat portion 714 from which the second tab 742b protrudes is referred to as the second main body portion 742a. ​​The third main body portion 743a is a portion of the electrode assembly flat portion 713. The third main body portion 743a is located between the first main body portion 741a and the second main body portion 742a, has the same width as the first main body portion 741a or the second main body portion 742a, and is a portion from which the first tab 741b does not protrude. The fourth main body portion 744a is located between the third main body portion 743a and the second main body portion 742a, has the same width as the first main body portion 741a or the second main body portion 742a, and is a portion from which the second tab 742b does not protrude. That is, first main body portion 741a is a flat, sheet-like, rectangular portion connected to first tab 741b, third main body portion 743a is a flat, sheet-like, rectangular portion not connected to first tab 741b, second main body portion 742a is a flat, sheet-like, rectangular portion connected to second tab 742b, and fourth main body portion 744a is a flat, sheet-like, rectangular portion not connected to second tab 742b.

[0048] The first main body portion 741a and the first tab 741b are collectively referred to as the first electrode plate portion 741, and the second main body portion 742a and the second tab 742b are collectively referred to as the second electrode plate portion 742. In other words, the first electrode plate portion 741 has a configuration in which the first tab 741b protrudes from the first main body portion 741a, and the second electrode plate portion 742 has a configuration in which the second tab 742b protrudes from the second main body portion 742a. ​​The third main body portion 743a is also referred to as the third electrode plate portion 743, and the fourth main body portion 744a is also referred to as the fourth electrode plate portion 744. In other words, the third electrode plate portion 743 has the same configuration as the third main body portion 743a with no protruding tab, and the fourth electrode plate portion 744 has the same configuration as the fourth main body portion 744a with no protruding tab. Each of the first electrode plate portion 741, the second electrode plate portion 742, the third electrode plate portion 743, and the fourth electrode plate portion 744 is also referred to as an electrode plate portion 740a. Similar to the electrode plate portion 740a of the positive electrode plate 740, the negative electrode plate 750 also has an electrode plate portion 750a.

[0049] Based on the above definitions, in this embodiment, as shown in FIG. 3 , first main body portion 741a is a portion having the same width in the X-axis direction as first tab 741b (for example, a rectangular portion extending from first tab 741b in the negative Z-axis direction and elongated in the Z-axis direction). When the width of first tab 741b in the X-axis direction is not constant, first main body portion 741a is a portion having the same width in the X-axis direction as the maximum width of first tab 741b. Similarly, second main body portion 742a is a portion having the same width in the X-axis direction as second tab 742b (for example, a rectangular portion extending from second tab 742b in the negative Z-axis direction). When the width of second tab 742b in the X-axis direction is not constant, second main body portion 742a is a portion having the same width in the X-axis direction as the maximum width of second tab 742b. The third main body portion 743a (third electrode plate portion 743) is located between the first main body portion 741a and the second main body portion 742a and has the same width as the first main body portion 741a or the second main body portion 742a, and the fourth main body portion 744a (fourth electrode plate portion 744) is located in a position sandwiching the second main body portion 742a between the third main body portion 743a in the X-axis direction and is a portion having the same width as the first main body portion 741a or the second main body portion 742a.

[0050] That is, the electrode body 700 is formed by winding the positive electrode plate 740 around a winding axis L extending in the Z-axis direction (first direction), and thereby stacking multiple electrode plate portions 740a of the positive electrode plate 740 in the Y-axis direction (second direction intersecting the first direction). The multiple electrode plate portions 740a each include a first electrode plate portion 741, a second electrode plate portion 742 aligned with the first electrode plate portion 741 in the Y-axis direction (second direction), and a third electrode plate portion 743 disposed between the first electrode plate portion 741 and the second electrode plate portion 742. The multiple electrode plate portions 740a further include a fourth electrode plate portion 744 disposed at a position where the second electrode plate portion 742 is sandwiched between the third electrode plate portion 743 and the fourth electrode plate portion 744.

[0051] Specifically, the plurality of electrode plate portions 740a include a plurality of first electrode plate portions 741 and a plurality of second electrode plate portions 742 aligned in the Y-axis direction (second direction), and a plurality of third electrode plate portions 743 arranged between the plurality of first electrode plate portions 741 and the plurality of second electrode plate portions 742. The plurality of electrode plate portions 740a further include a plurality of fourth electrode plate portions 744 arranged at positions where the plurality of second electrode plate portions 742 are sandwiched between the plurality of third electrode plate portions 743 and the plurality of fourth electrode plate portions 744.

[0052] The multiple first electrode plate portions 741 are arranged adjacent to each other in the Y-axis direction (second direction). In other words, the multiple electrode plate portions 740a of the positive electrode plate 740 are arranged alternately with the negative electrode plate 750 (and the separators 760a and 760b), but it can be said that the multiple electrode plate portions 740a are arranged adjacent to each other in the positive electrode plate 740. Therefore, it can be said that the multiple first electrode plate portions 741 are arranged adjacent to each other in the positive electrode plate 740 (multiple electrode plate portions 740a). Similarly, the multiple second electrode plate portions 742 are arranged adjacent to each other in the Y-axis direction, the multiple third electrode plate portions 743 are arranged adjacent to each other in the Y-axis direction, and the multiple fourth electrode plate portions 744 are arranged adjacent to each other in the Y-axis direction. That is, from the end of the electrode body 700 in the negative Y-axis direction toward the positive Y-axis direction, a plurality of first electrode plate portions 741 are arranged consecutively, a plurality of third electrode plate portions 743 are arranged consecutively, a plurality of second electrode plate portions 742 are arranged consecutively, and a plurality of fourth electrode plate portions 744 are arranged consecutively. Note that "arranged adjacent to each other in the Y-axis direction (second direction)" means that they are arranged in positions where they at least partially overlap when viewed from the Y-axis direction (second direction). In this embodiment, they are arranged in positions where they completely overlap when viewed from the Y-axis direction (positions where they are not misaligned in the X-axis and Z-axis directions). The same applies hereinafter.

[0053] The first electrode plate portion 741 and the second electrode plate portion 742 are arranged in positions sandwiching the winding axis L (on both sides of the winding axis L) in the Y-axis direction (second direction). Similarly, the third electrode plate portion 743 and the fourth electrode plate portion 744 are arranged in positions sandwiching the winding axis L (on both sides of the winding axis L) in the Y-axis direction. In other words, the plurality of first electrode plate portions 741 and the plurality of third electrode plate portions 743, and the plurality of second electrode plate portions 742 and the plurality of fourth electrode plate portions 744 are arranged in positions sandwiching the winding axis L (on both sides of the winding axis L) in the Y-axis direction. In other words, the plurality of electrode plate portions 740a are divided into two, the plurality of first electrode plate portions 741 and the plurality of third electrode plate portions 743, and the plurality of second electrode plate portions 742 and the plurality of fourth electrode plate portions 744, with the winding axis L sandwiched between them (on both sides of the winding axis L).

[0054] With this configuration, the first electrode plate portion 741 and the fourth electrode plate portion 744 become electrode plate portions 740a of the same turn of the positive electrode plate 740, and the second electrode plate portion 742 and the third electrode plate portion 743 become electrode plate portions 740a of the same turn of the positive electrode plate 740. Furthermore, the first electrode plate portion 741 and the second electrode plate portion 742 become electrode plate portions 740a of different turns of the positive electrode plate 740, and the third electrode plate portion 743 and the fourth electrode plate portion 744 become electrode plate portions 740a of different turns of the positive electrode plate 740. In other words, when the positive electrode plate 740 is wound, one first electrode plate portion 741 and one fourth electrode plate portion 744 are included in a predetermined turn of the positive electrode plate 740, and in this case, the second electrode plate portion 742 and the third electrode plate portion 743 are not included in the predetermined turn. Similarly, one second electrode plate portion 742 and one third electrode plate portion 743 are included in one turn of the positive electrode plate 740 that is different from the specified turn, and in this case, the first electrode plate portion 741 and the fourth electrode plate portion 744 are not included in the one turn that is different from the specified turn.

[0055] As described above, the first electrode plate portion 741 integrally includes a first main body portion 741a and a first tab 741b protruding from the first main body portion 741a. The first main body portion 741a is a rectangular portion parallel to the XZ plane, and the first tab 741b is a rectangular portion that protrudes continuously in the positive Z-axis direction from the edge of the first main body portion 741a in the positive Z-axis direction. The first tabs 741b of the first electrode plate portions 741 are arranged adjacent to each other in the Y-axis direction (second direction). Specifically, the first tabs 741b are arranged in positions where they at least partially overlap when viewed from the Y-axis direction (in this embodiment, they are at the same position in the X-axis direction).

[0056] Similarly, the second electrode plate portion 742 integrally includes a second main body portion 742a and a second tab 742b protruding from the second main body portion 742a. ​​The second main body portion 742a is a rectangular portion parallel to the XZ plane, and the second tab 742b is a rectangular portion protruding continuously in the positive Z-axis direction from the edge of the second main body portion 742a in the positive Z-axis direction. The second tabs 742b of the second electrode plate portions 742 are arranged adjacent to each other in the Y-axis direction. Specifically, the second tabs 742b are arranged at positions where they at least partially overlap when viewed from the Y-axis direction (in this embodiment, they are at the same position in the X-axis direction). Here, the second tabs 742b are arranged at positions where they at least partially overlap with the first tab 741b when viewed from the Y-axis direction (second direction) (in this embodiment, they are at the same position in the X-axis direction). Therefore, the first tabs 741b and the second tabs 742b are arranged at positions where they overlap when viewed from the Y-axis direction, that is, at the same position in the X-axis direction.

[0057] The third electrode plate portion 743 has a third body portion 743a between the first body portion 741a and the second body portion 742a, without having a tab between the first tab 741b and the second tab 742b. The fourth electrode plate portion 744 has a fourth body portion 744a between the third body portion 743a and the second body portion 742a, without having a tab between the first tab 741b and the second tab 742b. In other words, the first electrode plate portion 741 and the second electrode plate portion 742 are electrode plate portions 740a with tabs, while the third electrode plate portion 743 and the fourth electrode plate portion 744 are electrode plate portions 740a without tabs.

[0058] In such a configuration of the electrode plate portion 740a, the first tab 741b of the first electrode plate portion 741 and the second tab 742b of the second electrode plate portion 742 are joined to the current collector 500 in a bent state. Specifically, the first tab 741b and the second tab 742b are joined to the current collector 500 extending in the Y-axis direction (opposing each other in the Z-axis direction) in a bent state in the Y-axis direction (second direction). More specifically, the first tab 741b protrudes in the positive direction of the Z-axis from the first main body portion 741a and is joined to the current collector 500 in a bent state in the positive direction of the Y-axis (or is bent in the negative direction of the Y-axis and then bent in the positive direction of the Y-axis). The second tab 742b protrudes in the positive direction of the Z-axis from the second main body portion 742a and is bent in the negative direction of the Y-axis and is joined to the current collector 500 in a bent state in the positive direction of the Y-axis. This bonds first tab 741b, second tab 742b, and current collector 500 to one another. Specifically, tab group 720 formed by bundling a plurality of first tabs 741b and a plurality of second tabs 742b is bent in the Y-axis direction (second direction) and bonded to a surface of current collector 500 in the negative Z-axis direction. Note that there are no particular limitations on how first tab 741b and second tab 742b are bent in the Y-axis direction when bonded to current collector 500.

[0059] [3 Explanation of effects] As described above, in the energy storage element 10 according to the embodiment of the present invention, the first tab 741b of the first electrode plate portion 741 and the second tab 742b of the second electrode plate portion 742 are arranged in positions where they overlap when viewed from the second direction (Y-axis direction). The third electrode plate portion 743 does not have a tab between the first tab 741b and the second tab 742b, and the first tab 741b and the second tab 742b are joined to the current collector 500 in a folded state. In this way, in the electrode assembly 700, no tab of the third electrode plate portion 743 is provided between the first tab 741b of the first electrode plate portion 741 and the second tab 742b of the second electrode plate portion 742, and the first tab 741b and the second tab 742b are joined to the current collector 500 in a folded state. As a result, the first tab 741b and the second tab 742b are joined to the current collector 500, but because no tabs are disposed between the first tab 741b and the second tab 742b, it is possible to prevent the tabs from being crowded together when joined to the current collector 500. Therefore, even if the electrode body 700 has multiple tabs (first tab 741b and second tab 742b) joined to the current collector 500 in a bent state, it is possible to prevent the tabs from being crowded together and being damaged.

[0060] By arranging the first electrode plate portion 741 and the second electrode plate portion 742 at positions sandwiching the winding axis L, the first tab 741b and the second tab 742b are arranged at positions separated from each other. This makes it possible to prevent the tabs from being damaged due to being crowded together when joining the multiple tabs (first tabs 741b and second tabs 742b) to the current collector 500 in the electrode body 700.

[0061] The first electrode plate portion 741 and the second electrode plate portion 742 are arranged on different circumferences of the positive electrode plate 740. As a result, in the circumference where the first electrode plate portion 741 is arranged, current can be collected from the current collector 500 by the first tab 741b, and in the circumference where the second electrode plate portion 742 is arranged, current can be collected from the current collector 500 by the second tab 742b. Furthermore, the second electrode plate portion 742 and the third electrode plate portion 743 are arranged on the same circumference of the positive electrode plate 740. As a result, even if a tab is not provided on the third electrode plate portion 743, current can be collected from the current collector 500 by the second tab 742b in the circumference where the second electrode plate portion 742 is arranged. In this way, even when a configuration is adopted in which the tabs are not densely packed in the electrode assembly 700 and are therefore not likely to be damaged, current can still be collected efficiently from the current collector 500, thereby preventing a decrease in current collection performance for the current collector 500.

[0062] In the electrode assembly 700, a plurality of third electrode plate portions 743 are disposed between a plurality of first electrode plate portions 741 and a plurality of second electrode plate portions 742. This allows the plurality of first tabs 741b of the plurality of first electrode plate portions 741 and the plurality of second tabs 742b of the plurality of second electrode plate portions 742 to be bundled together and joined to the current collector 500, with a plurality of third electrode plate portions 743 without tabs sandwiched between them. Therefore, in the electrode assembly 700, the plurality of first tabs 741b and the plurality of second tabs 742b can be easily joined to the current collector 500, making it possible to easily realize a configuration that prevents damage to the tabs due to their being crowded together.

[0063] In the electrode body 700, the multiple first electrode plate portions 741 are arranged adjacent to each other in the second direction (Y-axis direction), and the multiple first tabs 741b of the multiple first electrode plate portions 741 are arranged adjacent to each other in the second direction. This allows the energy storage device 10 to be easily manufactured, thereby reducing manufacturing costs. Specifically, this is as follows.

[0064] For example, if other electrode plate portions 740a are arranged between multiple first electrode plate portions 741, when bundling the first tabs 741b, bundling the multiple first electrode plate portions 741 with the other electrode plate portions 740a sandwiched between them increases the number of electrode plate portions 740a to be bundled, making it difficult to bundle the multiple first tabs 741b. Therefore, by arranging the multiple first electrode plate portions 741 adjacent to each other in the second direction, the multiple first tabs 741b can be easily bundled and joined to the current collector 500. This makes it easy to manufacture the energy storage element 10, thereby reducing manufacturing costs.

[0065] Furthermore, when the multiple first tabs 741b are arranged offset in the width direction (X-axis direction) rather than adjacent to each other in the second direction (Y-axis direction) (the same position in the X-axis direction), arranging the multiple first tabs 741b so that they do not overlap increases the overall width of the multiple first tabs 741b, resulting in poor volumetric efficiency. When the multiple first tabs 741b are arranged so that they partially overlap in the width direction, when the positive electrode plate 740 is wound and the first tabs 741b overlap, the multiple first tabs 741b are connected, making it difficult to inspect the width of each individual first tab 741b. Therefore, the width of each individual first tab 741b must be inspected individually before winding the positive electrode plate 740, which increases manufacturing costs. In contrast, if multiple first tabs 741b are arranged adjacent to each other in the second direction, the widths of the multiple first tabs 741b can be inspected collectively using images or the like after winding the positive electrode plate 740, making it easier to manage the first tabs 741b and reducing manufacturing costs.

[0066] Furthermore, if multiple first tabs 741b are arranged in an overlapping manner, thicker and thinner portions are created due to the overlap, making it difficult to bundle the multiple first tabs 741b and join them to the current collector 500. Furthermore, if multiple first tabs 741b are arranged with a shift in the width direction, the width of the first tabs 741b needs to be narrow. However, if the width of the first tabs 741b is narrow, the first tabs 741b are likely to bend during manufacturing, making handling difficult. Slowing down the manufacturing speed or introducing equipment to prevent bending in order to prevent bending of the first tabs 741b would increase manufacturing costs. As a result, the configuration of this embodiment can reduce manufacturing costs.

[0067] In the electrode body 700, no tab is provided on the fourth electrode plate portion 744 that sandwiches the second electrode plate portion 742 with the third electrode plate portion 743. As a result, the first tab 741b of the first electrode plate portion 741 and the second tab 742b of the second electrode plate portion 742 are joined to the current collector 500, but no tab is arranged on the fourth electrode plate portion 744, so it is possible to prevent the tabs joined to the current collector 500 from being crowded together. Therefore, even if the electrode body 700 has multiple tabs (first tab 741b and second tab 742b) joined to the current collector 500 in a bent state, it is possible to prevent the tabs from being crowded together and being damaged.

[0068] In the above, the effects have been mainly described for the positive electrode side (tab group 720 side) of the energy storage element 10, but the same can be said for the negative electrode side (tab group 730 side).

[0069] [4 Explanation of Variations] (Variation 1) Next, a first modification of the above embodiment will be described. Fig. 6 is a cross-sectional view showing a configuration in which an electrode body 700 according to the first modification of the present embodiment is joined to a current collector 500. Specifically, Fig. 6 corresponds to Fig. 5, but the negative electrode plate 750 is not shown in Fig. 6.

[0070] 6, like the electrode body 700 in the above embodiment, the electrode body 700 in this modified example has multiple electrode plate portions 740a each including multiple first electrode plate portions 741, multiple second electrode plate portions 742, multiple third electrode plate portions 743, and multiple fourth electrode plate portions 744. However, in this modified example, multiple first tabs 741b of the multiple first electrode plate portions 741 are joined to a portion of the current collector 500 on the negative side of the Y-axis, whereas multiple second tabs 742b of the multiple second electrode plate portions 742 are joined to a portion of the current collector 500 on the positive side of the Y-axis.

[0071] That is, the second tab 742b is disposed at a position overlapping with the first tab 741b when viewed from the Y-axis direction (second direction), but is not overlapped with the first tab 741b in the Z-axis direction and is not joined to the first tab 741b. Specifically, the second tab 742b protrudes from the second main body portion 742a in the positive direction of the Z-axis, is slightly bent in the negative direction of the Y-axis, and is joined to a portion of the current collector 500 on the positive side of the Y-axis in a state where it is bent in the positive direction of the Y-axis. Note that the second tab 742b may protrude from the second main body portion 742a in the positive direction of the Z-axis, and then be bent in the positive direction of the Y-axis without being bent in the negative direction of the Y-axis, and then be joined to a portion of the current collector 500 on the positive side of the Y-axis. The other configurations are the same as those in the above-described embodiment, and therefore detailed description thereof will be omitted.

[0072] As described above, the energy storage element according to this modification can achieve the same effects as the above-described embodiment. In particular, in this modification, the second tab 742b is joined to a portion of the current collector 500 on the positive side of the Y axis, and therefore the length of the second tab 742b can be shortened. Furthermore, because the first tab 741b and the second tab 742b are not joined in an overlapping manner, the thickness of the group of tabs joined to the current collector 500 can be reduced. Note that there are no particular limitations on how the first tab 741b and the second tab 742b are bent in the Y axis direction when joined to the current collector 500. The same applies to the subsequent modifications.

[0073] (Variation 2) Next, a second modification of the above embodiment will be described. Fig. 7 is a cross-sectional view showing the configuration of an electrode assembly 700 according to the second modification of the present embodiment in a state where it is joined to a current collector 500. Specifically, Fig. 7 is a view corresponding to Fig. 6.

[0074] As shown in FIG. 7 , the electrode assembly 700 in this modification differs from the first modification in that the second tab 742b protrudes from the second main body portion 742a in the positive direction of the Z axis, is slightly bent in the positive direction of the Y axis, and is then bent in the negative direction of the Y axis and joined to a portion of the current collector 500 on the positive side of the Y axis. That is, in this modification, the second tab 742b is also positioned so as to overlap with the first tab 741b when viewed from the Y axis direction (second direction), but is not overlapped with the first tab 741b in the Z axis direction and is not joined to the first tab 741b. Note that the second tab 742b may protrude from the second main body portion 742a in the positive direction of the Z axis and then be bent in the negative direction of the Y axis without being bent in the positive direction of the Y axis, and then be joined to a portion of the current collector 500 on the positive side of the Y axis. The other configurations are the same as those in the first modification, and therefore detailed description thereof will be omitted.

[0075] As described above, the energy storage element according to this modification can achieve the same effects as those of the above-described modification 1. In this manner, second tab 742b may be joined to any position on current collector 500. Note that in this modification, second tab 742b may be arranged to overlap first tab 741b in the Z-axis direction and joined to first tab 741b.

[0076] (Variation 3) Next, a third modification of the above embodiment will be described. Fig. 8 is a cross-sectional view showing a configuration in which an electrode body 700 according to the third modification of the present embodiment is joined to a current collector 500. Specifically, Fig. 8 corresponds to Fig. 5, but the negative electrode plate 750 is not shown in Fig. 8.

[0077] 8, the electrode body 700 in this modification differs from the above embodiment in that the multiple first tabs 741b of the multiple first electrode plate portions 741 are arranged in the positive Z-axis direction of the current collector 500 and are joined to a surface of the current collector 500 in the positive Z-axis direction. In other words, the first tabs 741b and the second tabs 742b are arranged in positions that overlap when viewed from the Y-axis direction (second direction), but are not overlapped in a state of abutting in the Z-axis direction, and are arranged on different surfaces of the current collector 500 in the Z-axis direction and joined to the current collector 500. The other configuration is the same as in the above embodiment, and therefore detailed description will be omitted.

[0078] As described above, the energy storage element according to this modification can achieve the same effects as those of the above-described embodiment. In this manner, first tab 741b and second tab 742b may be joined to any surface of current collector 500.

[0079] In this modification, both first tab 741b and second tab 742b may be arranged in the positive Z-axis direction of current collector 500 and joined to the surface of current collector 500 in the positive Z-axis direction. Alternatively, current collector 500 may be configured with two plate-like members aligned in the Z-axis direction, and first tab 741b and second tab 742b may be arranged between the two plate-like members and joined to the two plate-like members.

[0080] In the above-described modification 1, as in the present modification 3, first tab 741b may be arranged in the positive direction of the Z axis of current collector 500 and joined to a surface of current collector 500 in the positive direction of the Z axis. In the above-described modification 2, as in the present modification 3, either or both of first tab 741b and second tab 742b may be arranged in the positive direction of the Z axis of current collector 500 and joined to a surface of current collector 500 in the positive direction of the Z axis.

[0081] (Variation 4) Next, a fourth modification of the above embodiment will be described. Fig. 9 is a cross-sectional view showing a configuration in which an electrode body 700 according to the fourth modification of the present embodiment is joined to a current collector 500. Specifically, Fig. 9 corresponds to Fig. 5, but the negative electrode plate 750 is not shown in Fig. 9.

[0082] 9, the electrode body 700 in this modification differs from the above embodiment in that a plurality of first electrode plate portions 741, a plurality of third electrode plate portions 743, a plurality of second electrode plate portions 742, and a plurality of fourth electrode plate portions 744 are arranged in the Y-axis direction at a position corresponding to the electrode body flat portion 713. Furthermore, a plurality of first electrode plate portions 741, a plurality of third electrode plate portions 743, a plurality of second electrode plate portions 742, and a plurality of fourth electrode plate portions 744 are arranged in the Y-axis direction at a position corresponding to the electrode body flat portion 714. The other configurations are the same as those in the above embodiment, and therefore detailed description thereof will be omitted.

[0083] As described above, the energy storage element according to this modification can achieve the same effects as those of the above embodiment. In this manner, any number of the first electrode plate portions 741, the third electrode plate portions 743, the second electrode plate portions 742, and the fourth electrode plate portions 744 may be arranged in the Y-axis direction.

[0084] (Other variations) Although the energy storage device according to the embodiment of the present invention (including its modified examples) has been described above, the present invention is not limited to this embodiment. The embodiment disclosed herein is an example in all respects, and the scope of the present invention includes all modifications within the meaning and scope equivalent to the claims. Note that, hereinafter, the content described for the above embodiment also applies to the above modified examples 1 to 4, and the content described for the positive electrode side (tab group 720 side) of the energy storage device 10 also applies to the negative electrode side (tab group 730 side).

[0085] For example, in the above embodiment, the first main body portion 741a of the first electrode plate portion 741 is a flat, sheet-like, rectangular portion connected to the first tab 741b and has the same width as the first tab 741b. However, even if the tab width of the first tab 741b varies depending on the location, the first main body portion 741a may have the same width as the maximum tab width of the first tab 741b at the portion connected to the first tab 741b. The same applies to the second main body portion 742a of the second electrode plate portion 742. The third main body portion 743a (third electrode plate portion 743) is located between the first main body portion 741a and the second main body portion 742a without having a tab between the first tab 741b and the second tab 742b, and has the same width as the first main body portion 741a or the second main body portion 742a, and the fourth main body portion 744a (fourth electrode plate portion 744) is located at a position where it sandwiches the second main body portion 742a between it and the third main body portion 743a without having a tab at a position where it sandwiches the second tab 742b between it and the first tab 741b, and it only needs to have the same width as the first main body portion 741a or the second main body portion 742a.

[0086] In the above embodiment, the electrode assembly 700 has an oval shape when viewed in the Z-axis direction. However, it may have an elliptical shape, a circular shape, or other shapes when viewed in the Z-axis direction. In this case, the first main body portion 741a may be a curved sheet-like portion having the same width as the maximum width of the first tab 741b. That is, as described above, the first main body portion 741a may be connected to the first tab 741b and have the same width as the maximum tab width of the first tab 741b. Similarly, the second main body portion 742a, the third main body portion 743a, and the fourth main body portion 744a may also be curved sheet-like portions. In this way, the first main body portion 741a, the second main body portion 742a, the third main body portion 743a, and the fourth main body portion 744a may be curved rather than flat as long as they are arranged side by side in the Y-axis direction.

[0087] In the above embodiment, a plurality of first electrode plate portions 741, second electrode plate portions 742, third electrode plate portions 743, and fourth electrode plate portions 744 are arranged. However, only one of the first electrode plate portion 741, second electrode plate portion 742, third electrode plate portion 743, and fourth electrode plate portion 744 may be arranged. For example, a configuration in which only one third electrode plate portion 743 is arranged between a plurality of first electrode plate portions 741 and a plurality of second electrode plate portions 742 may be used.

[0088] In the above embodiment, the first tab 741b and the second tab 742b of the electrode body 700 are joined to one current collector 500. However, the current collector 500 may be made up of multiple members having lead plates or the like, and the first tab 741b and the second tab 742b may be joined to the lead plates or the like.

[0089] In the above embodiment, the multiple first electrode plate portions 741 and the multiple second electrode plate portions 742 are arranged on different circumferences of the positive electrode plate 740, but any of the first electrode plate portions 741 and the second electrode plate portions 742 may be arranged on the same circumference.

[0090] In the above embodiment, the plurality of second electrode plate portions 742 and the plurality of third electrode plate portions 743 are arranged on the same circumference of the positive electrode plate 740, but any of the second electrode plate portions 742 and the third electrode plate portions 743 may be arranged on different circumferences.

[0091] In the above embodiment, the multiple first tabs 741b of the multiple first electrode plate portions 741 are arranged at the same position in the X-axis direction. However, the multiple first tabs 741b only need to be arranged at positions that overlap when viewed from the Y-axis direction, and may be arranged at positions that are slightly offset in the X-axis direction. The same applies to the first tabs 741b and the second tabs 742b. The same applies to the multiple second tabs 742b.

[0092] In the above embodiment, the electrode assembly 700 has the fourth electrode plate portion 744 at a position where the second electrode plate portion 742 is sandwiched between the fourth electrode plate portion 744 and the third electrode plate portion 743. However, the electrode assembly 700 does not have to have the fourth electrode plate portion 744. In other words, the second electrode plate portion 742 may be disposed at the position of the fourth electrode plate portion 744.

[0093] In the above embodiment, both the positive electrode side (tab group 720 side) and the negative electrode side (tab group 730 side) of the energy storage device 10 have the above configuration. However, either the positive electrode side or the negative electrode side may not have the above configuration.

[0094] Any combination of the above-described embodiments and modifications is also included within the scope of the present invention.

[0095] The present invention can be realized not only as an electricity storage element, but also as an electrode body 700 or a combination of an electrode body 700 and a current collector 500. [Industrial Applicability]

[0096] The present invention can be applied to an electric storage element such as a lithium ion secondary battery. [Explanation of symbols]

[0097] 10. Energy storage element 100 containers 110 Container body 120 Lid 200 electrode terminal 500 current collector 700 Electrode body 710 Electrode body part 711, 712 Electrode body curved portion 713, 714 Flat part of electrode body 720, 730 tab group 740 positive electrode plate 740a, 750a Pole plate part 741 First electrode plate section 741a First body part 741b, 751b first tab 742 Second pole plate section 742a Second body part 742b, 752b second tab 743 Third pole plate section 743a Third body part 744 Fourth pole plate section 744a Fourth body part 750 negative plate 760a, 760b separator

Claims

1. An energy storage element comprising: an electrode body; an electrode terminal; and a current collector connecting one of a positive electrode plate and a negative electrode plate of the electrode body to the electrode terminal, The electrode body is formed by winding the electrode plate around a winding axis extending in a first direction, so that a plurality of electrode plate portions of the electrode plate are stacked in a second direction intersecting the first direction, the plurality of electrode plate portions include a first electrode plate portion, a second electrode plate portion aligned with the first electrode plate portion in the second direction, and a third electrode plate portion disposed between the first electrode plate portion and the second electrode plate portion, The first electrode plate portion has a first body portion and a first tab protruding from the first body portion, The second electrode plate portion is a second main body portion and protrudes from the second main body portion. a second tab disposed at a position overlapping the first tab, the third electrode plate portion has a third body portion between the first body portion and the second body portion without having a tab between the first tab and the second tab, the first tab and the second tab are joined in a folded state to a surface of the current collector facing the first direction, The plurality of electrode plate portions include a plurality of the first electrode plate portions and a plurality of the second electrode plate portions aligned in the second direction, and a plurality of the third electrode plate portions arranged between the plurality of first electrode plate portions and the plurality of second electrode plate portions. Energy storage element.

2. An energy storage element comprising: an electrode body; an electrode terminal; and a current collector connecting one of a positive electrode plate and a negative electrode plate of the electrode body to the electrode terminal, The electrode body is formed by winding the electrode plate around a winding axis extending in a first direction, so that a plurality of electrode plate portions of the electrode plate are stacked in a second direction intersecting the first direction, the plurality of electrode plate portions include a first electrode plate portion, a second electrode plate portion aligned with the first electrode plate portion in the second direction, and a third electrode plate portion disposed between the first electrode plate portion and the second electrode plate portion, The first electrode plate portion has a first body portion and a first tab protruding from the first body portion, the second electrode plate portion has a second main body portion and a second tab that protrudes from the second main body portion and is arranged at a position that overlaps with the first tab when viewed from the second direction, the third electrode plate portion has a third body portion between the first body portion and the second body portion without having a tab between the first tab and the second tab, the first tab and the second tab are joined in a folded state to a surface of the current collector facing the first direction, the plurality of electrode plate portions include a plurality of first electrode plate portions adjacent to each other in the second direction, The first tabs of the first electrode plate portions are arranged adjacent to each other in the second direction. Energy storage element.

3. An energy storage element comprising: an electrode body; an electrode terminal; and a current collector connecting one of a positive electrode plate and a negative electrode plate of the electrode body to the electrode terminal, The electrode body is formed by winding the electrode plate around a winding axis extending in a first direction, so that a plurality of electrode plate portions of the electrode plate are stacked in a second direction intersecting the first direction, the plurality of electrode plate portions include a first electrode plate portion, a second electrode plate portion aligned with the first electrode plate portion in the second direction, and a third electrode plate portion disposed between the first electrode plate portion and the second electrode plate portion, The first electrode plate portion has a first body portion and a first tab protruding from the first body portion, the second electrode plate portion has a second main body portion and a second tab that protrudes from the second main body portion and is arranged at a position that overlaps with the first tab when viewed from the second direction, the third electrode plate portion has a third body portion between the first body portion and the second body portion without having a tab between the first tab and the second tab, the first tab and the second tab are joined to the current collector in a folded state, The first electrode plate portion and the second electrode plate portion are electrode plate portions of different turns of the electrode plate, The second electrode plate portion and the third electrode plate portion are electrode plate portions of the same turn of the electrode plate, The plurality of electrode plate portions include a plurality of the first electrode plate portions and a plurality of the second electrode plate portions aligned in the second direction, and a plurality of the third electrode plate portions arranged between the plurality of first electrode plate portions and the plurality of second electrode plate portions. Energy storage element.

4. an electrode body, an electrode terminal, and either a positive electrode plate or a negative electrode plate of the electrode body; a current collector connected to the electrode terminal, The electrode body is formed by winding the electrode plate around a winding axis extending in a first direction, so that a plurality of electrode plate portions of the electrode plate are stacked in a second direction intersecting the first direction, the plurality of electrode plate portions include a first electrode plate portion, a second electrode plate portion aligned with the first electrode plate portion in the second direction, and a third electrode plate portion disposed between the first electrode plate portion and the second electrode plate portion, The first electrode plate portion has a first body portion and a first tab protruding from the first body portion, the second electrode plate portion has a second main body portion and a second tab that protrudes from the second main body portion and is arranged at a position that overlaps with the first tab when viewed from the second direction, the third electrode plate portion has a third body portion between the first body portion and the second body portion without having a tab between the first tab and the second tab, the first tab and the second tab are joined to the current collector in a folded state, The first electrode plate portion and the second electrode plate portion are electrode plate portions of different turns of the electrode plate, The second electrode plate portion and the third electrode plate portion are electrode plate portions of the same turn of the electrode plate, the plurality of electrode plate portions include a plurality of first electrode plate portions adjacent to each other in the second direction, The first tabs of the first electrode plate portions are arranged adjacent to each other in the second direction. Energy storage element.

5. The first electrode plate portion and the second electrode plate portion are disposed at positions sandwiching the winding axis in the second direction. The energy storage element according to any one of claims 1 to 4.

6. The plurality of electrode plate portions further include a fourth electrode plate portion disposed at a position where the second electrode plate portion is sandwiched between the fourth electrode plate portion and the third electrode plate portion, The fourth electrode plate portion does not have a tab at a position where the second tab is sandwiched between the fourth electrode plate portion and the first electrode plate portion, and has a fourth body portion at a position where the second body portion is sandwiched between the fourth electrode plate portion and the third body portion. The energy storage element according to any one of claims 1 to 5.

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