Energy storage element

Abstract

The present invention provides an electricity storage element comprising a first electrode body formed by winding a first pole plate, and a second electrode body formed by winding a second pole plate. The first electrode body has a first positive electrode tab and a first negative electrode tab that project from a portion of a first electrode body unit. The second electrode body has a second positive electrode tab and a second negative electrode tab that project from a portion of a second electrode body unit. The first electrode body unit has a first pole plate terminal section at a position facing the second electrode body unit. The second electrode body unit has a second pole plate terminal section at a position facing the first electrode body unit. The first pole plate terminal section and the second pole plate terminal section are positioned so as not to overlap when seen from the direction in which the first electrode body and the second electrode body are aligned.

Description

[Technical Field]

[0001] The present invention relates to an energy storage element including a plurality of electrode assemblies each having a wound electrode plate and tabs. [Background technology]

[0002] Conventionally, there has been known an energy storage element including a plurality of electrode assemblies each having a tab, each of which is formed by winding electrode plates. Patent Document 1 discloses a prismatic secondary battery (energy storage element) including a plurality of flat wound groups (electrode assemblies) each having a tab, each of which is formed by winding a positive electrode and a negative electrode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 141613 Summary of the Invention [Problem to be solved by the invention]

[0004] In an energy storage device in which an electrode assembly with wound electrode plates is housed in a container, an electrode assembly with tabs, as in the conventional energy storage device, can generally occupy a larger proportion of the container than an electrode assembly without tabs. Therefore, in a configuration including an electrode assembly with tabs, as in the conventional energy storage device, it is generally possible to achieve a smaller size or higher capacity of the energy storage device. However, even in a configuration including an electrode assembly with tabs, as in the conventional energy storage device, when multiple electrode assemblies are arranged, wasted space may be generated between the multiple electrode assemblies. In such cases, there is a risk of the energy storage device becoming larger or its capacity decreasing, making it impossible to achieve a smaller size or higher capacity of the energy storage device.

[0005] The present invention was made by the inventors of the present application by focusing on the above-mentioned problems, and has an object to provide an energy storage element that can be made smaller and has a higher capacity. [Means for solving the problem]

[0006] An energy storage element according to one aspect of the present invention is an energy storage element comprising a first electrode body formed by winding a first electrode plate, and a second electrode body formed by winding a second electrode plate, wherein the first electrode body has a first electrode body main body portion and tabs protruding from a portion of the first electrode body main body, which are a first positive electrode tab and a first negative electrode tab, which are tabs on the positive and negative electrode sides; the second electrode body has a second electrode body main body portion and tabs protruding from a portion of the second electrode body main body, which are tabs on the positive and negative electrode sides; the first electrode body main body portion has a first electrode plate terminal end portion, which is the end of the winding of the first electrode plate, at a position opposite the second electrode body main body portion; and the second electrode body main body portion has a second electrode plate terminal end portion, which is the end of the winding of the second electrode plate, at a position opposite the first electrode body main body portion; and the first electrode plate terminal end portion and the second electrode plate terminal end portion are arranged in positions that do not overlap when viewed from the arrangement direction of the first electrode body and the second electrode body.

[0007] The present invention can be realized not only as such an energy storage element, but also as a combination of the first electrode body and the second electrode body. [Effects of the Invention]

[0008] According to the energy storage device of the present invention, it is possible to achieve a reduction in size or a high capacity. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view showing the appearance of an energy storage device according to an embodiment. [Figure 2] FIG. 2 is an exploded perspective view showing the components of the energy storage device according to the embodiment. [Figure 3] FIG. 3 is a perspective view showing the configuration of the first electrode body and the second electrode body according to the embodiment. [Figure 4] FIG. 4 is a top view showing the configuration of the first electrode body according to the embodiment. [Figure 5]FIG. 5 is a top view showing the configuration of the second electrode body according to the embodiment. [Figure 6] FIG. 6 is a top view showing the positional relationship between the first electrode body and the second electrode body according to the embodiment. [Figure 7] FIG. 7 is a top view showing an example of the arrangement positions of the tabs of the first electrode body and the second electrode body according to the first modification of the embodiment. [Figure 8] FIG. 8 is a top view showing an example of the arrangement positions of the electrode plate start ends of the first electrode body and the second electrode body according to the second modification of the embodiment. [Figure 9] FIG. 9 is a top view showing an example of the arrangement positions of the electrode plate start ends and tabs of the first electrode body and the second electrode body according to the third modification of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] An energy storage element according to one aspect of the present invention is an energy storage element comprising a first electrode body formed by winding a first electrode plate, and a second electrode body formed by winding a second electrode plate, wherein the first electrode body has a first electrode body main body portion and tabs protruding from a portion of the first electrode body main body, which are a first positive electrode tab and a first negative electrode tab, which are tabs on the positive and negative electrode sides; the second electrode body has a second electrode body main body portion and tabs protruding from a portion of the second electrode body main body, which are tabs on the positive and negative electrode sides; the first electrode body main body portion has a first electrode plate terminal end portion, which is the end of the winding of the first electrode plate, at a position opposite the second electrode body main body portion; and the second electrode body main body portion has a second electrode plate terminal end portion, which is the end of the winding of the second electrode plate, at a position opposite the first electrode body main body portion; and the first electrode plate terminal end portion and the second electrode plate terminal end portion are arranged in positions that do not overlap when viewed from the arrangement direction of the first electrode body and the second electrode body.

[0011] According to this, in the energy storage element, the first electrode body around which the first electrode plate is wound has a first electrode body main body portion, a first positive electrode tab, and a first negative electrode tab, and the second electrode body around which the second electrode plate is wound has a second electrode body main body portion, a second positive electrode tab, and a second negative electrode tab. The first electrode plate end portion of the first electrode body main body portion facing the second electrode body main body portion and the second electrode plate end portion of the second electrode body main body portion facing the first electrode body main body portion are arranged in positions where they do not overlap. In this way, the first electrode plate end portion of the first electrode body main body portion is arranged in a position facing the second electrode body main body portion, and the second electrode plate end portion of the second electrode body main body portion is arranged in a position facing the first electrode body main body portion but does not overlap with the first electrode plate end portion. This makes it possible to prevent wasted space from being generated between the first electrode body and the second electrode body (between the first electrode body main body portion and the second electrode body main body portion), thereby enabling the energy storage element to be made smaller or have a higher capacity.

[0012] The direction from the first positive electrode tab toward the first negative electrode tab and the direction from the second positive electrode tab toward the second negative electrode tab may be the same direction.

[0013] A configuration in which the first electrode plate end portion of the first electrode assembly is positioned opposite the second electrode assembly main body portion and the second electrode plate end portion of the second electrode assembly is positioned opposite the first electrode assembly main body portion can be achieved by rotating one of two identical electrode assemblies by 180 degrees. However, in this case, the first positive electrode tab and the second positive electrode tab are positioned in the opposite direction relative to the first negative electrode tab and the second negative electrode tab, making it difficult to connect tabs of the same polarity to a single current collector. Therefore, even if the first electrode plate end portion and the second electrode plate end portion are positioned as described above, the direction from the first positive electrode tab to the first negative electrode tab and the direction from the second positive electrode tab to the second negative electrode tab are aligned in the same direction. This allows the first positive electrode tab and the second positive electrode tab to be aligned in the same direction relative to the first negative electrode tab and the second negative electrode tab, making it easy to connect tabs of the same polarity to a single current collector.

[0014] At least one of the first positive electrode tab and the first negative electrode tab may be arranged to protrude from a portion of a region of the first electrode body main body opposite the second electrode body main body, beyond the region facing the second electrode body main body, and a tab of the same polarity as at least one of the second positive electrode tab and the second negative electrode tab may be arranged to protrude from a portion of a region of the second electrode body main body opposite the first electrode body main body, beyond the region facing the first electrode body main body.

[0015] A configuration in which the first electrode plate end portion of the first electrode body is positioned opposite the second electrode body main body portion and the second electrode plate end portion of the second electrode body is positioned opposite the first electrode body main body portion can be achieved by arranging two identical electrode bodies in the same orientation and adjusting the length of the electrode plates. This easily prevents wasted space from being created between the first and second electrode bodies (between the first and second electrode body main body portions), making it easy to achieve a smaller and higher-capacity energy storage device. However, in this case, the tab of one of the first and second electrode bodies is positioned opposite the other electrode body. This results in the tabs of the same polarity on the first and second electrode bodies being closer to each other, resulting in crowded tabs and potentially wasted space or difficulty in connecting them to the current collector. For this reason, at least one tab of the first electrode body is arranged to protrude from a portion of the first electrode body main body opposite the second electrode body main body, and a tab of the second electrode body having the same polarity as the tab is arranged to protrude from a portion of the second electrode body main body opposite the first electrode body main body. In other words, the tabs of the same polarity possessed by the first and second electrode bodies are arranged on opposite sides of the portions facing each other's electrode body main body. This allows the tabs of the same polarity possessed by the first and second electrode bodies to be spaced apart, thereby preventing the tabs from being wasted and making the tabs easier to bend and connect to the current collector.

[0016] At least one of the first electrode body main body portion and the second electrode body main body portion has a pair of curved portions formed by winding at least one of the first electrode plate and the second electrode plate, and a flat portion connecting the pair of curved portions, and at least one of the first electrode plate terminal portion and the second electrode plate terminal portion may be arranged on the flat portion.

[0017] According to this, at least one of the first and second electrode plate termination portions is disposed on a flat portion of at least one of the first and second electrode body main bodies. This allows the electrode plate termination portions to be fixed to the electrode body on a flat portion, making it possible to easily fix the electrode plate termination portions to the electrode body with tape or the like. If flat portions are formed on both the first and second electrode body main bodies, the electrode plate termination portions can be sandwiched between the flat portions of both the first and second electrode body main bodies, making it easy to fix the electrode plate termination portions to the electrode body.

[0018] The first electrode plate termination portion may extend toward the second electrode plate termination portion at a portion of the first electrode body main body portion facing the second electrode body main body portion, and the second electrode plate termination portion may extend toward the first electrode plate termination portion at a portion of the second electrode body main body portion facing the first electrode body main body portion.

[0019] According to this, by arranging both the first electrode plate terminal end portion and the second electrode plate terminal end portion so that they extend toward each other in the first electrode body main body portion and the second electrode body main body portion, the overall lengths of both the first electrode plate and the second electrode plate can be increased, which makes it possible to effectively utilize the space between the first electrode body and the second electrode body and increase the capacity of the first electrode body and the second electrode body, thereby enabling the energy storage element to be made smaller or have a higher capacity.

[0020] The first electrode body main body portion further has a first electrode plate starting end portion which is the winding start portion of the first electrode plate, and the second electrode body main body portion further has a second electrode plate starting end portion which is the winding start portion of the second electrode plate, and the first electrode plate starting end portion and the second electrode plate starting end portion may protrude in directions opposite to each other when viewed from the arrangement direction of the first electrode body and the second electrode body, and may be positioned so as not to overlap.

[0021] According to this, the starting end of the first electrode plate of the first electrode body main body and the starting end of the second electrode plate of the second electrode body main body are positioned so as not to overlap when viewed in the arrangement direction of the first electrode body and the second electrode body, which reduces the overlap between the first electrode plate and the second electrode plate, thereby enabling the energy storage element to be made smaller or have a higher capacity.

[0022] 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.

[0023] In the following description and drawings, the X-axis direction refers to the arrangement direction of a pair of electrode terminals (positive and negative, hereinafter) of the energy storage element, the arrangement direction of a pair of current collectors, the width direction of the first and second electrode bodies, or the direction in which the short sides of the container face each other. The Y-axis direction refers to the arrangement direction of the first and second electrode bodies, the stacking direction of the electrode plates of the first and second electrode bodies, the thickness direction of the first and second electrode bodies, the direction in which the long sides of the container face each other, or the thickness direction of the container. The Z-axis direction refers to the direction in which the winding axis of the first and second electrode bodies extends, the height direction of the first and second electrode bodies, the arrangement direction of the electrode terminals, current collectors, and first and second electrode bodies, 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). 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.

[0024] In the following description, the positive X-axis direction refers to the direction of the arrow on the X-axis, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. The same applies to the Y-axis and Z-axis. Expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the direction or attitude is not strictly 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, that is, there is a difference of, for example, a few percent.

[0025] (Embodiment) [1 General Description of Energy Storage Element 10] First, a general description of an energy storage device 10 according to the present embodiment will be given. Fig. 1 is a perspective view showing the appearance of the energy storage device 10 according to the present embodiment. Fig. 2 is an exploded perspective view showing the components of the energy storage device 10 according to the present embodiment. Of the components included in the energy storage device 10, the container body 110 of the container 100 is not shown in Fig. 2.

[0026] The energy storage device 10 is a secondary battery (single cell) that can charge and discharge electricity, and specifically, is a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage device 10 is used for power storage or power supply purposes. The energy storage device 10 is used as a battery for driving or starting the engine of a mobile object such as an automobile, motorcycle, personal watercraft, ship, snowmobile, agricultural machinery, construction machinery, 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 device 10 can also be used as a stationary battery for home or business use.

[0027] 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.

[0028] As shown in FIG. 1, the energy storage device 10 includes a container 100 (a container body 110 and a lid 120), a pair of electrode terminals 200 (positive and negative electrode sides), and a pair of upper gaskets 300 (positive and negative electrode sides). As shown in FIG. 2, the container 100 (container body 110) contains a pair of lower gaskets 400 (positive and negative electrode sides), a pair of current collectors 500 (positive and negative electrode sides), a first electrode assembly 600, and a second electrode assembly 700. An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but is not shown in the figure. There are no particular limitations on the type of electrolyte, and various electrolytes can be selected as long as they do not impair the performance of the energy storage device 10. In addition to the above components, spacers may be placed to the sides or below the first electrode body 600 and the second electrode body 700, insulating tape to fix (bind) the first electrode body 600 and the second electrode body 700, insulating film to wrap the first electrode body 600 and the second electrode body 700, etc.

[0029] 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 long side walls 111 on both side surfaces (long side surfaces) in the Y-axis direction, a pair of flat, rectangular short side walls 112 on both side surfaces (short side surfaces) in the X-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 extends in the X-axis direction and constitutes the lid of the container 100, and is disposed in the positive Z-axis direction of the container body 110. The lid 120 is provided with a gas exhaust valve 121 for releasing the pressure inside the container 100 if the pressure inside the container 100 rises excessively, and a liquid injection section 122 for injecting the electrolyte into the container 100.

[0030] With this configuration, the container 100 is structured so that the inside is sealed by accommodating the first electrode body 600, the second electrode body 700, etc. 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.

[0031] The first electrode body 600 and the second electrode body 700 are each electricity storage elements (power generation elements) that include a positive electrode plate, a negative electrode plate, and a separator and can store electricity. Specifically, the first electrode body 600 and the second electrode body 700 are each so-called horizontally wound electrode bodies that are oval when viewed from the Z-axis direction and are formed by winding layers of positive electrode plates, negative electrode plates, and separators sandwiched between them.

[0032] Specifically, in the first electrode assembly 600, a plurality of tabs of positive electrode plates are stacked to form a first positive electrode tab 620, which is a positive electrode side tab bundle, and a plurality of tabs of negative electrode plates are stacked to form a first negative electrode tab 630, which is a negative electrode side tab bundle. That is, the first electrode assembly 600 has a first electrode assembly main body 610 and a first positive electrode tab 620 and a first negative electrode tab 630, which are tabs protruding from a portion of the first electrode assembly main body 610 in the positive direction of the Z axis and which are positive electrode side and negative electrode side tabs. Similarly, in the second electrode assembly 700, a plurality of tabs of positive electrode plates are stacked to form a second positive electrode tab 720, which is a positive electrode side tab bundle, and a plurality of tabs of negative electrode plates are stacked to form a second negative electrode tab 730, which is a negative electrode side tab bundle. That is, the second electrode body 700 has a second electrode body main body portion 710, and a second positive electrode tab 720 and a second negative electrode tab 730 which are tabs on the positive electrode side and negative electrode side that protrude from a part of the second electrode body main body portion 710 in the positive direction of the Z axis. A detailed description of the configurations of the first electrode body 600 and the second electrode body 700 will be given later.

[0033] The electrode terminals 200 are terminal members (positive electrode terminal and negative electrode terminal) electrically connected to the first electrode body 600 and the second electrode body 700 via the current collector 500. In other words, the electrode terminals 200 are metal members that lead out electricity stored in the first electrode body 600 and the second 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 first electrode body 600 and the second 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 120.

[0034] 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. 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.

[0035] The current collectors 500 are flat, rectangular current collecting members (positive electrode current collector and negative electrode current collector) that electrically connect the first electrode body 600 and the second electrode body 700 to the electrode terminal 200. Specifically, the positive electrode side current collector 500 is connected (joined) to the first positive electrode tab 620 of the first electrode body 600 and the second positive electrode tab 720 of the second electrode body 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 negative electrode side current collector 500 is connected (joined) to the first negative electrode tab 630 of the first electrode body 600 and the second negative electrode tab 730 of the second electrode body 700 by welding or the like, and is also joined to the negative electrode side electrode terminal 200 by crimping or the like, as described above.

[0036] The material of the current collector 500 is not particularly limited, but 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 of connecting (joining) the current collector 500 to the first positive electrode tab 620 and the second positive electrode tab 720 or the first negative electrode tab 630 and the second negative electrode tab 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.

[0037] The upper gasket 300 is a flat, electrically insulating sealing member disposed between the lid 120 and the electrode terminal 200 of the container 100. The lower gasket 400 is a flat, electrically 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.

[0038] [2. Description of the Configuration of the First Electrode Body 600 and the Second Electrode Body 700] Next, the configurations of the first electrode body 600 and the second electrode body 700 will be described in detail. Fig. 3 is a perspective view showing the configurations of the first electrode body 600 and the second electrode body 700 according to this embodiment. Since the first electrode body 600 and the second electrode body 700 have the same configuration, Fig. 3 shows the configurations of the first electrode body 600 and the second electrode body 700 using the same diagram. Specifically, (a) of Fig. 3 shows the configuration of the first electrode body 600 (or the second electrode body 700) in a partially unfolded wound state, and (b) of Fig. 3 shows the configuration of the first electrode body 600 (or the second electrode body 700) after winding.

[0039] As described above, the first electrode assembly 600 and the second electrode assembly 700 have similar configurations. Therefore, the following description will focus on the configuration of the first electrode assembly 600, and a description of the configuration of the second electrode assembly 700 will be simplified or omitted. As shown in FIG. 3(a), the first electrode assembly 600 has first electrode plates 640 and 650 and first separators 661 and 662, and is formed by alternately stacking and winding the first electrode plates 640 and 650 and the first separators 661 and 662. In this embodiment, the first electrode plate 640 is a positive electrode plate, and the first electrode plate 650 is a negative electrode plate. That is, the first electrode assembly 600 is formed by stacking and winding the positive electrode side first electrode plate 640, the first separator 661, the negative electrode side first electrode plate 650, and the first separator 662 in this order. In this embodiment, the negative first electrode plate 650 is arranged at the innermost periphery (innermost layer) and outermost periphery (outermost layer) of the first electrode plates 640 and 650 when the first electrode plates 640 and 650 are wound.

[0040] The first electrode plate 640 on the positive electrode side is an electrode plate (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 first electrode plate 650 on the negative electrode side is an electrode plate (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 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 lithium ions.

[0041] Positive electrode active materials include polyanion compounds such as LiMPO4, LiMSiO4, and LiMBO3 (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), lithium titanate, LiMn2O4, and LiMn 1.5 Ni 0.5Examples 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.

[0042] The first separators 661 and 662 are microporous sheets made of resin. Any known material can be used as the material for the first separators 661 and 662 as long as it does not impair the performance of the energy storage element 10. The first separators 661 and 662 can be made of a woven fabric or nonwoven fabric that is insoluble in organic solvents, a synthetic resin microporous film made of a polyolefin resin such as polyethylene, or the like.

[0043] The first electrode plate 640 has, at its end in the positive Z-axis direction, a plurality of rectangular tabs 641 protruding in the positive Z-axis direction, and the plurality of tabs 641 are arranged in a stacked state in the Y-axis direction. Similarly, the first electrode plate 650 has, at its end in the positive Z-axis direction, a plurality of rectangular tabs 651 protruding in the positive Z-axis direction, and the plurality of tabs 651 are arranged in a stacked state in the Y-axis direction. The tabs 641 and 651 are portions where no active material layer is formed and the base material layer is exposed. The shapes of the tabs 641 and 651 are not particularly limited.

[0044] As shown in (b) of FIG. 3, a plurality of stacked tabs 641 are bundled together to form a first positive electrode tab 620 that extends and protrudes in the positive direction of the Z axis. Similarly, a plurality of stacked tabs 651 are bundled together to form a first negative electrode tab 630 that extends and protrudes in the positive direction of the Z axis. In this embodiment, the first positive electrode tab 620 and the first negative electrode tab 630 are arranged to protrude in the positive direction of the Z axis from a part of a first electrode assembly flat portion 611 described below. The first positive electrode tab 620 and the first negative electrode tab 630 are joined to a surface of the current collector 500 facing each other in the Y axis direction, facing the positive direction of the Y axis, and then bent in the positive direction of the Y axis together with the current collector 500.

[0045] The first electrode body main body portion 610 is a portion that constitutes the main body of the first electrode body 600, and specifically, is a portion of the first electrode body 600 other than the first positive electrode tab 620 and the first negative electrode tab 630. In other words, the first electrode body main body portion 610 is an elongated columnar or cylindrical portion formed by winding together the portions of the first electrode plates 640 and 650 on which the active material layers are formed and the first separators 661 and 662. As a result, the first electrode body main body portion 610 has a pair of first electrode body flat portions 611 and 612 on both sides in the Y-axis direction, and a pair of first electrode body curved portions 613 and 614 on both sides in the X-axis direction.

[0046] The first electrode body flat portion 611 is a portion that connects a pair of first electrode body curved portions 613 and 614, has a flat and rectangular shape extending parallel to the XZ plane facing the negative Y-axis direction, and is disposed opposite the long side wall portion 111 of the container body 110 in the negative Y-axis direction. The first electrode body flat portion 612 is a portion that connects the pair of first electrode body curved portions 613 and 614, has a flat and rectangular shape extending parallel to the XZ plane facing the positive Y-axis direction, and is disposed opposite the second electrode body 700. The first electrode body curved portion 613 is a curved portion that curves in a semicircular arc shape so as to protrude in the negative X-axis direction when viewed from the Z-axis direction, and extends in the Z-axis direction, and is disposed opposite the short side wall portion 112 of the container body 110 in the negative X-axis direction. The first electrode body curved portion 614 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 extends in the Z-axis direction, and is positioned opposite the short side wall portion 112 of the container body 110 in the positive X-axis direction.

[0047] Similarly, the second electrode body 700 has second electrode plates 740 and 750 and second separators 761 and 762, and is formed by alternately stacking and winding the second electrode plates 740 and 750 and the second separators 761 and 762. In this embodiment, the second electrode plate 740 is a positive electrode plate, and the second electrode plate 750 is a negative electrode plate. The second electrode plate 740 has a tab 741, and the second electrode plate 750 has a tab 751. A plurality of tabs 741 are bundled together to form the second positive electrode tab 720, and a plurality of tabs 751 are bundled together to form the second negative electrode tab 730.

[0048] In the present embodiment, the second positive electrode tab 720 is disposed at a position corresponding to the first negative electrode tab 630, and the second negative electrode tab 730 is disposed at a position corresponding to the first positive electrode tab 620. In other words, the second positive electrode tab 720 and the second negative electrode tab 730 are disposed at positions opposite to those of the first positive electrode tab 620 and the first negative electrode tab 630. In other words, the second electrode plate 740 has a tab 741 at a position corresponding to the tab 651 of the first electrode plate 650, and the second electrode plate 750 has a tab 751 at a position corresponding to the tab 641 of the first electrode plate 640. It can also be said that the second electrode plate 740 is disposed at a position corresponding to the first electrode plate 650, and the second electrode plate 750 is disposed at a position corresponding to the first electrode plate 640 (the positions of the positive electrode plates and negative electrode plates are reversed between the first electrode assembly 600 and the second electrode assembly 700). However, like the first electrode plate 650, when the second electrode plates 740 and 750 are wound, the negative second electrode plate 750 is arranged at the innermost periphery (innermost layer) and outermost periphery (outermost layer) of the second electrode plates 740 and 750. In Fig. 3, the second electrode assembly 700 is illustrated so that the stacking order of the positive and negative electrode plates is reversed to that of the first electrode assembly 600, but the positions of the tabs of the positive and negative electrode plates may be reversed to that of the first electrode assembly 600, and the positive and negative electrode plates may be wound in the same stacking order as the first electrode assembly 600.

[0049] The second electrode body main body 710 of the second electrode body 700 has a pair of second electrode body flat portions 711 and 712 on both sides in the Y-axis direction, and a pair of second electrode body curved portions 713 and 714 on both sides in the X-axis direction. In the present embodiment, the second electrode body flat portion 711 is arranged at a position corresponding to the first electrode body flat portion 612 of the first electrode body 600, and the second electrode body flat portion 712 is arranged at a position corresponding to the first electrode body flat portion 611 of the first electrode body 600. In other words, the second positive electrode tab 720 and the second negative electrode tab 730 are arranged to protrude in the positive direction of the Z-axis from a part of the second electrode body flat portion 712. The second electrode body curved portion 713 is arranged at a position corresponding to the first electrode body curved portion 614 of the first electrode body 600, and the second electrode body curved portion 714 is arranged at a position corresponding to the first electrode body curved portion 613 of the first electrode body 600.

[0050] As shown in FIG. 2, the second electrode body 700 is rotated 180° around the Z axis from the state shown in FIG. 3(b) and is disposed in the positive direction of the Y axis of the first electrode body 600. As a result, the second electrode body flat portion 711 is disposed facing the first electrode body 600 while facing the negative direction of the Y axis. The second electrode body flat portion 712 is disposed facing the long side wall portion 111 of the container body 110 facing the positive direction of the Y axis while facing the positive direction of the Y axis. The second electrode body curved portion 713 is disposed facing the short side wall portion 112 of the container body 110 facing the negative direction of the X axis so as to protrude in the negative direction of the X axis. The second electrode body curved portion 714 is disposed facing the short side wall portion 112 of the container body 110 facing the positive direction of the X axis so as to protrude in the positive direction of the X axis.

[0051] In this way, at least one of the first electrode body main body portion 610 and the second electrode body main body portion 710 has a pair of curved portions formed by winding at least one of the first electrode plates 640, 650 and the second electrode plates 740, 750, and a flat portion connecting the pair of curved portions. In this embodiment, both the first electrode body main body portion 610 and the second electrode body main body portion 710 have a pair of curved portions formed by winding the first electrode plates 640, 650 and the second electrode plates 740, 750, and a flat portion connecting the pair of curved portions.

[0052] [3. Details of the first electrode body 600 and the second electrode body 700 and explanation of their positional relationship] Next, the first electrode body 600 and the second electrode body 700 will be described in more detail, and the positional relationship between them will be described. FIG. 4 is a top view showing the configuration of the first electrode body 600 according to this embodiment. FIG. 5 is a top view showing the configuration of the second electrode body 700 according to this embodiment. FIG. 6 is a top view showing the positional relationship between the first electrode body 600 and the second electrode body 700 according to this embodiment. Specifically, FIGS. 4 and 5 are views of the first electrode body 600 and the second electrode body 700 as viewed from the positive direction of the Z axis, and FIG. 6 is a view of the configuration when the first electrode body 600 shown in FIG. 4 and the second electrode body 700 shown in FIG. 5 are assembled together as viewed from the positive direction of the Z axis.

[0053] In the first electrode assembly 600, the first electrode plates 640 and 650 are wound together, and although the negative first electrode plate 650 is slightly longer in the winding direction than the positive first electrode plate 640, they have roughly the same shape when viewed from the positive direction of the Z axis. For convenience of explanation, in FIGS. 4 and 6, one of the first electrode plates 640 and 650 of the first electrode assembly 600 (e.g., the first electrode plate 640) and the first separators 661 and 662 are not shown, and only the other electrode plate (e.g., the first electrode plate 650) is shown wound. Similarly, in FIGS. 5 and 6 for the second electrode assembly 700, one of the second electrode plates 740 and 750 (e.g., the second electrode plate 740) and the second separators 761 and 762 are not shown, and only the other electrode plate (e.g., the second electrode plate 750) is shown wound. 4 to 6 show simplified diagrams in which the number of turns of the first electrode plate 650 (or 640) and the number of turns of the second electrode plate 750 (or 740) are reduced.

[0054] 4, in the first electrode assembly 600, the first electrode assembly main body portion 610 has a first electrode plate starting end 612a and a first electrode plate terminal end 612b. The first electrode plate starting end 612a is the winding start portion of the first electrode plate 650 (or 640), and in this embodiment, is located at the end in the negative Y-axis direction and in the center in the X-axis direction of the first electrode assembly flat portion 612. The first electrode plate starting end 612a is located on the innermost periphery (innermost layer) of the first electrode plate 650 (or 640), and is the tip portion of the electrode plate extending in the positive X-axis direction from the first electrode assembly curved portion 613.

[0055] The first electrode plate terminal end 612b is the end portion of the winding of the first electrode plate 650 (or 640), and in this embodiment is located at the end in the positive Y-axis direction and the center in the X-axis direction of the first electrode body flat portion 612. The first electrode plate terminal end 612b is located at the outermost periphery (outermost layer) of the first electrode plate 650 (or 640), and is the tip portion of the electrode plate extending in the negative X-axis direction from the first electrode body curved portion 614. The first electrode plate terminal end 612b is located further in the positive X-axis direction than the first electrode plate starting end 612a. In other words, the first electrode plate terminal end 612b is located in a position that does not overlap with the first electrode plate starting end 612a when viewed in the Y-axis direction.

[0056] 5, in the second electrode body 700, the second electrode body main portion 710 has a second electrode plate starting end 711a and a second electrode plate terminal end 711b. The second electrode plate starting end 711a is the winding start portion of the second electrode plate 750 (or 740), and in this embodiment, is located at the end in the positive Y-axis direction and in the center in the X-axis direction of the second electrode body flat portion 711. The second electrode plate starting end 711a is located on the innermost periphery (innermost layer) of the second electrode plate 750 (or 740), and is the tip portion of the electrode plate extending in the negative X-axis direction from the second electrode body curved portion 714.

[0057] The second electrode plate terminal end portion 711b is the end portion of the second electrode plate 750 (or 740), and in this embodiment is located at the end of the second electrode body flat portion 711 in the negative Y-axis direction and in the center in the X-axis direction. The second electrode plate terminal end portion 711b is located on the outermost periphery (outermost layer) of the second electrode plate 750 (or 740), and is the tip portion of the electrode plate extending in the positive X-axis direction from the second electrode body curved portion 713. The second electrode plate terminal end portion 711b is located further in the negative X-axis direction than the second electrode plate starting end portion 711a. In other words, the second electrode plate terminal end portion 711b is located in a position that does not overlap with the second electrode plate starting end portion 711a when viewed in the Y-axis direction.

[0058] In this way, at least one of the first electrode plate terminal end portion 612b and the second electrode plate terminal end portion 711b is arranged on a flat portion of the electrode body main body portion. In this embodiment, both the first electrode plate terminal end portion 612b and the second electrode plate terminal end portion 711b are arranged on a flat portion of the electrode body main body portion (the first electrode body flat portion 612 and the second electrode body flat portion 711). Similarly, at least one of the first electrode plate starting end portion 612a and the second electrode plate starting end portion 711a is arranged on a flat portion of the electrode body main body portion. In this embodiment, both the first electrode plate starting end portion 612a and the second electrode plate starting end portion 711a are arranged on a flat portion of the electrode body main body portion (the first electrode body flat portion 612 and the second electrode body flat portion 711).

[0059] 6, the first electrode plate terminal end portion 612b of the first electrode body 600 is disposed at a position facing the second electrode body main portion 710 of the second electrode body 700 (a position facing the second electrode body flat portion 711). Specifically, the first electrode plate terminal end portion 612b extends to the center of the portion of the first electrode body main portion 610 that faces the second electrode body main portion 710. Because the portion of the first electrode body main portion 610 that faces the second electrode body main portion 710 is the first electrode body flat portion 612, the first electrode plate terminal end portion 612b extends to the center of the first electrode body flat portion 612 in the X-axis direction.

[0060] The second electrode plate terminal end portion 711b of the second electrode body 700 is disposed at a position facing the first electrode body main body portion 610 of the first electrode body 600 (a position facing the first electrode body flat portion 612). Specifically, the second electrode plate terminal end portion 711b extends to the center of the portion of the second electrode body main body portion 710 that faces the first electrode body main body portion 610. Because the portion of the second electrode body main body portion 710 that faces the first electrode body main body portion 610 is the second electrode body flat portion 711, the second electrode plate terminal end portion 711b extends to the center of the second electrode body flat portion 711 in the X-axis direction.

[0061] As a result, the first plate termination portion 612b and the second plate termination portion 711b are arranged facing each other in the X-axis direction with their tips facing each other. In other words, the first plate termination portion 612b and the second plate termination portion 711b are arranged to protrude in directions facing each other when viewed in the arrangement direction (Y-axis direction) of the first electrode body 600 and the second electrode body 700. In other words, the first plate termination portion 612b extends toward the second plate termination portion 711b at a portion of the first electrode body main body portion 610 facing the second electrode body main body portion 710. The second plate termination portion 711b extends toward the first plate termination portion 612b at a portion of the second electrode body main body portion 710 facing the first electrode body main body portion 610. The first plate termination portion 612b and the second plate termination portion 711b are arranged in positions that do not overlap when viewed in the arrangement direction (Y-axis direction) of the first electrode body 600 and the second electrode body 700. In this embodiment, the first electrode plate terminal portion 612b and the second electrode plate terminal portion 711b are arranged with a gap in the X-axis direction when viewed from the Y-axis direction, but they may also be arranged without a gap in the X-axis direction. Specifically, the distance between the first electrode plate terminal portion 612b and the second electrode plate terminal portion 711b is preferably 50% or less, more preferably 30% or less, and even more preferably 10% or less of the length in the X-axis direction of the first electrode body main portion 610 or the second electrode body main portion 710.

[0062] In this embodiment, the first plate termination portion 612b and the second plate termination portion 711b are not positioned so as to extend beyond each other's termination portions and not overlap, but are positioned in front of each other's termination portions and not overlap. In other words, the first plate termination portion 612b is not positioned so as to extend beyond the second plate termination portion 711b in the X-axis direction and not overlap with the second plate termination portion 711b, but is positioned in front of the second plate termination portion 711b and not overlap with the second plate termination portion 711b. Similarly, the second plate termination portion 711b is not positioned so as to extend beyond the first plate termination portion 612b in the X-axis direction and not overlap with the first plate termination portion 612b, but is positioned in front of the first plate termination portion 612b and not overlap with the first plate termination portion 612b.

[0063] The first electrode plate starting end 612a of the first electrode body 600 and the second electrode plate starting end 711a of the second electrode body 700 are arranged opposite each other in the X-axis direction, as viewed from the Y-axis direction, with their tips facing each other. That is, the first electrode plate starting end 612a and the second electrode plate starting end 711a protrude in directions opposite each other and are arranged in positions that do not overlap, as viewed from the arrangement direction (Y-axis direction) of the first electrode body 600 and the second electrode body 700. In this embodiment, the first electrode plate starting end 612a and the second electrode plate starting end 711a are arranged with a gap in the X-axis direction as viewed from the Y-axis direction, but they may also be arranged without a gap in the X-axis direction. Similarly, the first electrode plate starting end 612a and the first electrode plate terminal end 612b are arranged with a gap in the X-axis direction as viewed from the Y-axis direction, but they may also be arranged without a gap in the X-axis direction. The second electrode plate starting end 711a and the second electrode plate terminal end 711b are arranged with a gap in the X-axis direction when viewed from the Y-axis direction, but may be arranged without a gap in the X-axis direction.

[0064] Specifically, the distance between the first electrode plate starting end 612a and the second electrode plate starting end 711a is preferably 50% or less, more preferably 30% or less, and even more preferably 10% or less of the length in the X-axis direction of the first electrode body main portion 610 or the second electrode body main portion 710. The same applies to the distance between the first electrode plate starting end 612a and the first electrode plate terminal end 612b, and the distance between the second electrode plate starting end 711a and the second electrode plate terminal end 711b.

[0065] The configuration and positional relationship of the first separators 661 and 662 and the second separators 761 and 762 are not particularly limited, but can be similar to the configuration and positional relationship of the second electrode plate 750 (or 740) and the second electrode plate 750 (or 740).

[0066] As described above, the first electrode plate starting end 612a and the first electrode plate terminal end 612b are arranged on the first electrode assembly flat portion 612 facing the second electrode assembly 700, while the first positive electrode tab 620 and the first negative electrode tab 630 are arranged on the first electrode assembly flat portion 611 on the opposite side from the second electrode assembly 700. The second electrode plate starting end 711a and the second electrode plate terminal end 711b are arranged on the second electrode assembly flat portion 712 facing the first electrode assembly 600, while the second positive electrode tab 720 and the second negative electrode tab 730 are arranged on the second electrode assembly flat portion 712 on the opposite side from the first electrode assembly 600.

[0067] That is, at least one of the first positive electrode tab 620 and the first negative electrode tab 630 is arranged so as to protrude from a part of a region (first electrode body flat portion 611) of the first electrode body main body portion 610 opposite the second electrode body main body portion 710 relative to a region (first electrode body flat portion 612) of the first electrode body main body portion 610 that faces the second electrode body main body portion 710. Of the second positive electrode tab 720 and the second negative electrode tab 730, a tab having the same polarity as at least one of the first positive electrode tab 620 and the first negative electrode tab 630 is arranged so as to protrude from a part of a region (second electrode body flat portion 712) of the second electrode body main body portion 710 opposite the first electrode body main body portion 610 relative to a region (second electrode body flat portion 711) of the second electrode body main body portion 610 that faces the first electrode body main body portion 610. In this embodiment, both the first positive electrode tab 620 and the first negative electrode tab 630 are arranged so as to protrude from a part of the first electrode body flat portion 611 of the first electrode body main body portion 610 opposite the second electrode body main body portion 710. Both the second positive electrode tab 720 and the second negative electrode tab 730 are arranged to protrude from a part of the second electrode body flat portion 712 of the second electrode body main body portion 710 on the side opposite to the first electrode body main body portion 610.

[0068] The first positive electrode tab 620 is disposed at the end of the first electrode body flat portion 611 in the negative X-axis direction, and the first negative electrode tab 630 is disposed at the end of the first electrode body flat portion 611 in the positive X-axis direction. The second positive electrode tab 720 is disposed at the end of the second electrode body flat portion 712 in the negative X-axis direction, and the second negative electrode tab 730 is disposed at the end of the second electrode body flat portion 712 in the positive X-axis direction. With this configuration, the direction from the first positive electrode tab 620 to the first negative electrode tab 630 is the same as the direction from the second positive electrode tab 720 to the second negative electrode tab 730. In other words, the direction from the first positive electrode tab 620 to the first negative electrode tab 630 and the direction from the second positive electrode tab 720 to the second negative electrode tab 730 are not only parallel to the X-axis direction, but also in the same direction (same orientation) as one direction in the X-axis direction (in this embodiment, the positive X-axis direction).

[0069] In other words, the first positive electrode tab 620 and the second positive electrode tab 720 are arranged in the same direction (negative X-axis direction) as the first negative electrode tab 630 and the second negative electrode tab 730. That is, the first positive electrode tab 620 and the second positive electrode tab 720 are arranged on the same side of the center positions of the first electrode assembly 600 and the second electrode assembly 700 in the X-axis direction. The first negative electrode tab 630 and the second negative electrode tab 730 are arranged on the opposite side of the center positions of the first electrode assembly 600 and the second electrode assembly 700 in the X-axis direction from the first positive electrode tab 620 and the second positive electrode tab 720. Specifically, the first positive electrode tab 620 and the second positive electrode tab 720 are arranged in overlapping positions when viewed from the Y-axis direction, and the first negative electrode tab 630 and the second negative electrode tab 730 are arranged in overlapping positions when viewed from the Y-axis direction. In this embodiment, the first positive electrode tab 620 and the second positive electrode tab 720 are arranged at the same position in the X-axis direction, and the first negative electrode tab 630 and the second negative electrode tab 730 are arranged at the same position in the X-axis direction.

[0070] [4. Explanation of effects] As described above, according to the energy storage device 10 of the embodiment of the present invention, the first electrode body 600 formed by winding the first electrode plates 640 and 650 has a first electrode body main body portion 610, a first positive electrode tab 620, and a first negative electrode tab 630. The second electrode body 700 formed by winding the second electrode plates 740 and 750 has a second electrode body main body portion 710, a second positive electrode tab 720, and a second negative electrode tab 730. The first electrode plate terminal end portion 612b of the first electrode body main body portion 610, which faces the second electrode body main body portion 710, and the second electrode plate terminal end portion 711b of the second electrode body main body portion 710, which faces the first electrode body main body portion 610, are arranged in positions that do not overlap. In this way, the first electrode plate termination portion 612b of the first electrode body main portion 610 is arranged in a position facing the second electrode body main portion 710, and the second electrode plate termination portion 711b of the second electrode body main portion 710 is arranged in a position facing the first electrode body main portion 610 and in a position not overlapping with the first electrode plate termination portion 612b. This makes it possible to prevent wasted space from being created between the first electrode body 600 and the second electrode body 700 (between the first electrode body main portion 610 and the second electrode body main portion 710), thereby enabling the miniaturization or high capacity of the energy storage device 10. However, arranging the first electrode plate termination portion 612b and the second electrode plate termination portion 711b in a position not overlapping does not include arranging the first electrode plate termination portion 612b and the second electrode plate termination portion 711b in a position not overlapping beyond each other's end portions.

[0071] In other words, when the first electrode plate termination portion 612b of the first electrode body main body portion 610 is positioned facing the inner surface of the second electrode body main body portion 710 or the container 100, wasted space is generated between the portion of the first electrode body main body portion 610 where the first electrode plate termination portion 612b is not positioned and the inner surface of the second electrode body main body portion 710 or the container 100. For this reason, the first electrode plate termination portion 612b is positioned facing the second electrode body main body portion 710, and the second electrode plate termination portion 711b is positioned facing the first electrode body main body portion 610 but not overlapping with the first electrode plate termination portion 612b. This allows the second electrode plate termination portion 711b to be positioned in the portion of the first electrode body main body portion 610 where the first electrode plate termination portion 612b is not positioned, thereby preventing the generation of the wasted space and enabling the energy storage device 10 to be made smaller or have a higher capacity.

[0072] When the first electrode plate terminal end portion 612b and the second electrode plate terminal end portion 711b are arranged so that there is no gap between them in the X-axis direction when viewed from the Y-axis direction, the electrode plates can be made longer than when they are arranged with a gap between them. In this case, the space between the first electrode body 600 and the second electrode body 700 can be used more effectively, and the energy storage device 10 can be made smaller or have a higher capacity.

[0073] A configuration in which the first electrode plate termination portion 612b of the first electrode assembly 600 is positioned opposite the second electrode assembly main body portion 710 and the second electrode plate termination portion 711b of the second electrode assembly 700 is positioned opposite the first electrode assembly main body portion 610 can be realized by rotating one of two identical electrode assemblies by 180 degrees. The above configuration can be realized by defining the electrode assembly obtained by rotating the first electrode assembly 600 by 180 degrees as the second electrode assembly 700, and defining the first electrode plate termination portion 612b of the first electrode assembly 600 rotated by 180 degrees as the second electrode plate termination portion 711b. However, in this case, the first positive electrode tab 620 and the second positive electrode tab 720 are positioned in the opposite direction relative to the first negative electrode tab 630 and the second negative electrode tab 730, making it difficult to connect tabs of the same polarity to a single current collector 500. Therefore, even when the first electrode plate terminal portion 612b and the second electrode plate terminal portion 711b are arranged as described above, the direction from the first positive electrode tab 620 to the first negative electrode tab 630 and the direction from the second positive electrode tab 720 to the second negative electrode tab 730 are arranged in the same direction. As a result, the first positive electrode tab 620 and the second positive electrode tab 720 are arranged in the same direction relative to the first negative electrode tab 630 and the second negative electrode tab 730, and therefore tabs of the same polarity can be easily connected to one current collector 500.

[0074] A configuration in which the first electrode plate terminal end portion 612b of the first electrode assembly 600 is positioned opposite the second electrode assembly main body portion 710, and the second electrode plate terminal end portion 711b of the second electrode assembly 700 is positioned opposite the first electrode assembly main body portion 610, can be achieved by arranging two identical electrode assemblies in the same orientation and adjusting the lengths of the electrode plates. The above configuration can be achieved by adjusting the lengths of the first electrode plates 640 and 650 of the first electrode assembly 600 to be the same as the lengths of the second electrode plates 740 and 750 without rotating the first electrode assembly 600, and defining this as the second electrode assembly 700. This configuration can be achieved by arranging two electrode assemblies with different plate lengths, in which the electrode plates are wound in the same direction from the same winding start position and in the same direction from the positive electrode tab to the negative electrode tab (the positions of the positive electrode tab and negative electrode tab are the same), and adjusting the lengths of the electrode plates (the winding end positions of the electrode plates). This makes it possible to easily prevent wasted space from being created between the first electrode body 600 and the second electrode body 700 (between the first electrode body main body portion 610 and the second electrode body main body portion 710), making it easy to reduce the size or increase the capacity of the storage element 10.

[0075] However, in this case, the tab of either the first electrode body 600 or the second electrode body 700 ends up being positioned at a position facing the other electrode body. In other words, if the first electrode body 600 is defined as the second electrode body 700 without being rotated, the first positive electrode tab 620 and the first negative electrode tab 630 protrude from the first electrode body flat portion 611, and therefore the second positive electrode tab 720 and the second negative electrode tab 730 protrude from the second electrode body flat portion 711. As a result, the distance between the tabs of the same polarity on the first electrode body 600 and the second electrode body 700 becomes closer, and the tabs are crowded together, which may result in wasted space or make it difficult to connect them to the current collector 500. For this reason, at least one tab of the first electrode body 600 is arranged to protrude from a portion of the first electrode body main body portion 610 opposite the second electrode body main body portion 710, and a tab of the second electrode body 700 having the same polarity as the tab is arranged to protrude from a portion of the second electrode body main body portion 710 opposite the first electrode body main body portion 610. In other words, the tabs of the same polarity possessed by the first electrode body 600 and the second electrode body 700 are arranged on opposite sides of the portions facing each other's electrode body main body. This allows the tabs of the same polarity possessed by the first electrode body 600 and the second electrode body 700 to be arranged at positions spaced apart, thereby preventing the tabs from being wasted and making the tabs easier to bend and connect to the current collector 500.

[0076] At least one of the first electrode plate termination portion 612b and the second electrode plate termination portion 711b is arranged on a flat portion of at least one of the first electrode body main body portion 610 and the second electrode body main body portion 710. This allows the electrode plate termination portion to be fixed to the flat portion in the electrode body, making it easy to fix the electrode plate termination portion to the electrode body with tape or the like. In this embodiment, flat portions (first electrode body flat portion 612 and second electrode body flat portion 711) are formed on both the first electrode body main body portion 610 and the second electrode body main body portion 710. Therefore, the electrode plate termination portion can be sandwiched between the flat portions (first electrode body flat portion 612 and second electrode body flat portion 711) of both the first electrode body main body portion 610 and the second electrode body main body portion 710, making it easy to fix the electrode plate termination portion.

[0077] By arranging both the first electrode plate terminal end portion 612b and the second electrode plate terminal end portion 711b so that they extend toward each other in the first electrode body main portion 610 and the second electrode body main portion 710, the overall lengths of the first electrode plates 640 and 650 and the second electrode plates 740 and 750 can be increased. This allows the space between the first electrode body 600 and the second electrode body 700 to be effectively utilized, and the capacity of the first electrode body 600 and the second electrode body 700 can be increased, thereby enabling the energy storage device 10 to be miniaturized or have a higher capacity. Specifically, the distance between the first electrode plate terminal end portion 612b and the second electrode plate terminal end portion 711b is preferably 50% or less, more preferably 30% or less, and even more preferably 10% or less of the length in the X-axis direction of the first electrode body main portion 610 or the second electrode body main portion 710. The closer the distance between the first electrode plate terminal end 612b and the second electrode plate terminal end 711b, the more effectively the space between the first electrode body 600 and the second electrode body 700 can be utilized, and the greater the capacity of the first electrode body 600 and the second electrode body 700 can be increased.

[0078] The first electrode plate starting end 612a of the first electrode body main portion 610 and the second electrode plate starting end 711a of the second electrode body main portion 710 are arranged in positions where they do not overlap when viewed from the arrangement direction (Y-axis direction) of the first electrode body 600 and the second electrode body 700. This reduces the overlap between the first electrode plate 650 (or 640) and the second electrode plate 750 (or 740), allowing the energy storage element 10 to be made smaller or have a higher capacity.

[0079] The above-described configuration can be applied to both the first electrode plates 640 and 650. However, because the negative electrode side first electrode plate 650 is disposed at the innermost periphery (innermost layer) and outermost periphery (outermost layer) of the first electrode plates 640 and 650, applying the configuration to the first electrode plate 650 can enhance the above-described effects more than applying the configuration to the first electrode plate 640. Applying the configuration to both the first electrode plates 640 and 650 can enhance the above-described effects more than applying the configuration to just one of the first electrode plates 640 and 650. The first separators 661 and 662 are thin and therefore not very effective, but the above-described effects can be achieved by configuring them in the same way as the first electrode plate 650 (or 640). The same applies to the second electrode plates 740 and 750 and the second separators 761 and 762.

[0080] [5. Explanation of Variations] Although the energy storage device 10 according to the embodiment of the present invention has been described above, the present invention is not limited to this 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.

[0081] In the above embodiment, the positions of the tabs (first positive electrode tab 620 and first negative electrode tab 630, and second positive electrode tab 720 and second negative electrode tab 730) of the first electrode assembly 600 and the second electrode assembly 700 are not particularly limited. Specifically, they are as follows.

[0082] In the above embodiment, at least one of the first positive electrode tab 620 and the first negative electrode tab 630 may be arranged to protrude from the first electrode assembly flat portion 612, or at least one of the second positive electrode tab 720 and the second negative electrode tab 730 may be arranged to protrude from the second electrode assembly flat portion 711. That is, as shown in FIG. 7 , the first positive electrode tab 620 and the first negative electrode tab 630 may be arranged to protrude from a part of the portion of the first electrode assembly main body portion 610 that faces the second electrode assembly main body portion 710 (the first electrode assembly flat portion 612). The second positive electrode tab 720 and the second negative electrode tab 730 may be arranged to protrude from a part of the portion of the second electrode assembly main body portion 710 that faces the first electrode assembly main body portion 610 (the second electrode assembly flat portion 711). FIG. 7 is a top view showing an example of the arrangement positions of the tabs of the first electrode assembly 600a and the second electrode assembly 700a according to Variation 1 of this embodiment. Specifically, FIG. 7 is a view corresponding to FIG. 6 . In cases where bundling the first positive electrode tab 620 and the second positive electrode tab 720 makes it easier to join them to the current collector 500, the configuration of this modified example is preferable.

[0083] In the above embodiment, the direction from the first positive electrode tab 620 to the first negative electrode tab 630 may be different from the direction from the second positive electrode tab 720 to the second negative electrode tab 730. The first positive electrode tab 620 and the first negative electrode tab 630 may be disposed in reverse positions, or the second positive electrode tab 720 and the second negative electrode tab 730 may be disposed in reverse positions.

[0084] In the above embodiment, the first positive electrode tab 620 and the second positive electrode tab 720 may be arranged offset in the X-axis direction so as not to overlap when viewed in the Y-axis direction. The same applies to the first negative electrode tab 630 and the second negative electrode tab 730. As described above, the arrangement positions of the tabs of the first electrode assembly 600 and the second electrode assembly 700 are not particularly limited, and various configurations are possible.

[0085] In the above embodiment, the first electrode plate starting end 612a and the first electrode plate terminal end 612b of the first electrode body 600 are arranged in the center in the X-axis direction of the first electrode body flat portion 612, and the second electrode plate starting end 711a and the second electrode plate terminal end 711b of the second electrode body 700 are arranged in the center in the X-axis direction of the second electrode body flat portion 711. However, the following configuration is also possible.

[0086] In the above embodiment, the first electrode plate starting end portion may be arranged on the first electrode assembly flat portion 611, and the second electrode plate starting end portion may be arranged on the second electrode assembly flat portion 712. FIG. 8 is a top view showing an example of the arrangement positions of the electrode plate starting ends of the first electrode assembly 600b and the second electrode assembly 700b according to Modification 2 of the present embodiment. Specifically, FIG. 8 is a view corresponding to FIG. 6. As shown in FIG. 8, the first electrode plate starting end portion 611a is arranged in the center in the X-axis direction of the first electrode assembly flat portion 611, and the second electrode plate starting end portion 712a is arranged in the center in the X-axis direction of the second electrode assembly flat portion 712. The first electrode plate starting end portion 611a and the second electrode plate starting end portion 712a are arranged in positions that protrude in directions opposite to each other and do not overlap when viewed from the arrangement direction (Y-axis direction) of the first electrode assembly 600b and the second electrode assembly 700b.

[0087] In the above embodiment, the first electrode plate starting end 612a may be disposed at the end of the first electrode body flat portion 612 in the X-axis direction, and the second electrode plate starting end 711a may be disposed at the end of the second electrode body flat portion 711 in the X-axis direction. The first electrode plate starting end 612a may be disposed at the end of the first electrode body flat portion 612 in the negative X-axis direction, and the second electrode plate starting end 711a may be disposed at the end of the second electrode body flat portion 711 in the negative X-axis direction or the end of the second electrode body flat portion 711 in the positive X-axis direction. The first electrode plate starting end 612a may be disposed at the first electrode body curved portion 613 or 614, and the second electrode plate starting end 711a may be disposed at the second electrode body curved portion 713 or 714. The first electrode plate starting end 612a may be disposed at the first electrode body curved portion 613, and the second electrode plate starting end 711a may be disposed at the second electrode body curved portion 713 or 714. The same applies to the first electrode plate starting end 611a and the second electrode plate starting end 712a shown in FIG. 8.

[0088] In the above embodiment, the first electrode plate starting end 612a and the second electrode plate starting end 711a may be arranged in overlapping positions when viewed from the Y-axis direction. The first electrode plate starting end 612a and the second electrode plate starting end 711a may be arranged in any positions other than those described above. The same applies to the first electrode plate starting end 611a and the second electrode plate starting end 712a shown in FIG. 8. FIG. 9 is a top view showing an example of the arrangement of the electrode plate starting ends and tabs of the first electrode body 600 and the second electrode body 700c according to Modification 3 of this embodiment. Specifically, FIG. 9 corresponds to FIG. 6. As shown in FIG. 9, the first electrode plate starting end 612a and the second electrode plate starting end 712a are arranged in overlapping positions when viewed from the Y-axis direction. In this modification, the second positive electrode tab 720 and the second negative electrode tab 730 are arranged to protrude from a portion of the second electrode body main body 710 facing the first electrode body main body 610 (the second electrode body flat portion 711). That is, in this modified example, the second electrode body 700c is an electrode body having the same configuration as the first electrode body 600, with the winding end portion of the electrode plate extended to the position of the second electrode body flat portion 711. In other words, the first electrode body 600 and the second electrode body 700c are two electrode bodies in which the electrode plates are wound in the same direction from the same winding start position, the positive electrode tab and the negative electrode tab are positioned in the same position, and the winding end positions of the electrode plates are made different (adjusted by making the electrode plate lengths different).

[0089] In the above embodiment, the first plate termination portion 612b may be arranged at the X-axis direction end of the first electrode body flat portion 612, and the second plate termination portion 711b may be arranged at the X-axis direction end of the second electrode body flat portion 711. The first plate termination portion 612b may be arranged at the X-axis direction end of the first electrode body flat portion 612, and the second plate termination portion 711b may be arranged at a position at the X-axis direction end of the second electrode body flat portion 711 that does not overlap with the first plate termination portion 612b when viewed from the Y-axis direction in the X-axis direction, or at the X-axis direction end of the second electrode body flat portion 711. The same applies when the first plate termination portion 612b is arranged at the X-axis direction end of the first electrode body flat portion 612.

[0090] In the above embodiment, the first plate termination portion 612b may be arranged in the first electrode body curved portion 613 or 614, and the second plate termination portion 711b may be arranged in the second electrode body curved portion 713 or 714. The first plate termination portion 612b may be arranged in a position facing the second electrode body curved portion 714 of the first electrode body curved portion 614. In this case, the second plate termination portion 711b may be arranged in a position facing the first electrode body curved portion 614 of the second electrode body curved portion 714 and not overlapping with the first plate termination portion 612b when viewed from the Y-axis direction, or may be arranged in a position facing the first electrode body curved portion 613 of the second electrode body curved portion 713. The same applies when the first plate termination portion 612b is arranged in the first electrode body curved portion 613.

[0091] In the above embodiment, both first electrode plates 640 and 650 have the above configuration, but either one of first electrode plates 640 and 650 does not have to have the above configuration. However, as described above, since negative electrode first electrode plate 650 is disposed at the innermost periphery (innermost layer) and outermost periphery (outermost layer) of first electrode plates 640 and 650, applying the above configuration to first electrode plate 650 can be more effective than applying the above configuration to first electrode plate 640. For this reason, it is preferable that first electrode plate 650 has the above configuration. It is even more preferable that both first electrode plates 640 and 650 have the above configuration. The same applies to second electrode plates 740 and 750.

[0092] In the above embodiment, the number of turns (number of layers) of the electrode plates of the first electrode body 600 and the second electrode body 700 is not particularly limited, and the number of turns (number of layers) of the electrode plates of the first electrode body 600 and the second electrode body 700 may be the same or different. By adjusting the number of turns of the first electrode body 600 and the second electrode body 700 and adjusting the length of the electrode plates, the above various configurations can be realized.

[0093] In the above embodiment, the first electrode body 600 and the second electrode body 700 have an oval shape when viewed from the Z-axis direction, but at least one of the first electrode body 600 and the second electrode body 700 may have an elliptical shape, a circular shape, or the like when viewed from the Z-axis direction, and the shape is not particularly limited. In other words, at least one of the first electrode body main body 610 and the second electrode body main body 710 may have no flat portion. In an electrode body without a flat portion, the electrode plate starting end and electrode plate terminal end are arranged in a curved portion.

[0094] In the above embodiment, the first electrode body 600 and the second electrode body 700 are so-called horizontally wound electrode bodies whose winding axes are perpendicular to the lid body 120, but they may also be so-called vertically wound electrode bodies whose winding axes are parallel to the lid body 120. Even in this case, a configuration similar to that of the above embodiment can be realized by forming a tab on the vertically wound wound electrode body.

[0095] Any combination of the above-described embodiments and modifications is also included within the scope of the present invention.

[0096] The present invention can be realized not only as such an energy storage element, but also as a combination of the first electrode body and the second electrode body. [Industrial Applicability]

[0097] The present invention can be applied to an electric storage element such as a lithium ion secondary battery. [Explanation of symbols]

[0098] 10. Energy storage element 100 containers 110 Container body 120 Lid 200 electrode terminal 300 Upper Gasket 400 Lower Gasket 500 current collector 600, 600a, 600b First electrode body 610 First electrode main body part 611, 612 First electrode body flat part 611a, 612a First electrode plate starting end 612b First plate end 613, 614 First electrode body curved portion 620 First positive electrode tab 630 First negative electrode tab 640, 650 First plate 641, 651, 741, 751 tabs 661, 662 First separator 700, 700a, 700b, 700c Second electrode body 710 Second electrode main body part 711, 712 Second electrode body flat part 711a, 712a Starting end of second electrode plate 711b Second plate end 713, 714 Second electrode body curved portion 720 Second positive electrode tab 730 Second negative electrode tab 740, 750 Second plate 761, 762 Second separator

Claims

1. An energy storage element including a first electrode body formed by winding a first electrode plate and a second electrode body formed by winding a second electrode plate, the first electrode body has a first electrode body main body portion, and tabs protruding from a part of the first electrode body main body portion, the tabs being a positive electrode side and a negative electrode side, a first positive electrode tab and a first negative electrode tab, the second electrode body has a second electrode body main body portion, and tabs protruding from a part of the second electrode body main body portion, the second positive electrode tab and the second negative electrode tab being tabs on the positive electrode side and the negative electrode side, the first electrode body main body portion has a first electrode plate terminal end portion, which is a winding end portion of the first electrode plate, at a position facing the second electrode body main body portion, the second electrode body main body portion has a second electrode plate terminal end portion, which is a winding end portion of the second electrode plate, at a position facing the first electrode body main body portion, The first electrode plate end portion and the second electrode plate end portion are positioned in front of each other's end portions when viewed from the arrangement direction of the first electrode body and the second electrode body, and are arranged at positions where they do not overlap. Energy storage element.

2. The direction from the first positive electrode tab to the first negative electrode tab is the same as the direction from the second positive electrode tab to the second negative electrode tab. The energy storage element according to claim 1 .

3. at least one of the first positive electrode tab and the first negative electrode tab is arranged to protrude from a part of a portion of the first electrode body main body portion that is on the opposite side to the second electrode body main body portion relative to a portion facing the second electrode body main body portion, The tab having the same polarity as at least one of the second positive electrode tab and the second negative electrode tab is disposed so as to protrude from a part of a portion of the second electrode body main body portion that is on the opposite side to the first electrode body main body portion relative to a portion facing the first electrode body main body portion. The energy storage element according to claim 2 .

4. At least one of the first electrode body main body portion and the second electrode body main body portion has a pair of curved portions formed by winding at least one of the first electrode plate and the second electrode plate, and a flat portion connecting the pair of curved portions, At least one of the first electrode plate end portion and the second electrode plate end portion is disposed on the flat portion. The energy storage element according to any one of claims 1 to 3.

5. the first electrode plate terminal end portion extends toward the second electrode plate terminal end portion at a portion of the first electrode body main portion facing the second electrode body main portion, and is located in front of the second electrode plate terminal end portion; The second electrode plate end portion extends toward the first electrode plate end portion at a portion of the second electrode body main portion facing the first electrode body main portion, and is located in front of the first electrode plate end portion. The energy storage element according to any one of claims 1 to 4.

Images