Electrical energy storage element

Abstract

This electrical energy storage element comprises: an electrode body with stacked electrode plates; a container accommodating the electrode body; and a pair of terminals electrically connected to the electrode body and disposed outside the container. The electrode body comprises: an electrode body main body; and a pair of tab parts protruding from one side of the electrode body main body. The electrode body main body has a shape based on a rectangle when viewed from the stacking direction of the electrode plates, and comprises a pair of first cutout parts in which a pair of adjacent corner parts from among the corner parts of the rectangle are cut out in a chamfered shape. The container accommodating the electrode body has a shape based on a rectangle when viewed from the stacking direction, and comprises a pair of second cutout parts in which a pair of corner parts corresponding to the first cutout parts from among the corner parts of the rectangle are cut out in a chamfered shape. A terminal is disposed at each of the pair of second cutout parts.

Description

Electric energy storage element

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

[0002] Patent Document 1 discloses a rectangular secondary battery including a wound electrode body in which a positive electrode and a negative electrode are wound around a winding axis with a separator interposed therebetween.

[0003] Japanese Patent Application Laid-Open No. 2017-27681

[0004] In recent years, there has been a demand for secondary batteries that can achieve higher energy density.

[0005] The present invention has been made by the inventors of the present application newly paying attention to the above problems, and an object thereof is to provide a secondary battery capable of increasing the volumetric energy density as a system.

[0006] The electric energy storage element according to one aspect of the present invention includes an electrode body in which electrode plates are laminated, a container that houses the electrode body, and a pair of terminals that are electrically connected to the electrode body and disposed outside the container. The electrode body includes an electrode body main body and a pair of tab portions protruding from one side of the electrode body main body. The electrode body main body has a shape based on a rectangle when viewed from the stacking direction of the electrode plates, and includes a pair of first cutouts in which a pair of adjacent corners among the corners of the rectangle are chamfered. The container that houses the electrode body has a shape based on a rectangle when viewed from the stacking direction, and includes a pair of second cutouts in which a pair of corners corresponding to the first cutouts among the corners of the rectangle are chamfered. The terminals are disposed in each of the pair of second cutouts.

[0007] According to the present invention, it is possible to provide an electric energy storage element capable of increasing the volumetric energy density as a system.

[0008] Figure 1 is a perspective view showing the external appearance of an energy storage element according to an embodiment. Figure 2 is an exploded perspective view showing the components arranged inside the container of the energy storage element according to an embodiment. Figure 3 is an exploded perspective view of an energy storage element according to modification 1. Figure 4 is an exploded perspective view of an energy storage element according to modification 2. Figure 5 is an exploded perspective view of an energy storage element according to modification 3. Figure 6 is a schematic diagram showing an energy storage device equipped with an energy storage element according to an embodiment.

[0009] (1) An energy storage element according to one aspect of the present invention comprises an electrode body in which electrode plates are stacked, a container for housing the electrode body, and a pair of terminals electrically connected to the electrode body and arranged outside the container, wherein the electrode body comprises an electrode body main body and a pair of tab portions protruding from one side of the electrode body main body, the electrode body main body has a rectangular shape when viewed from the stacking direction of the electrode plates, and comprises a pair of first notches in which a pair of adjacent corners of the rectangle are cut out in a chamfered manner, the container for housing the electrode body has a rectangular shape when viewed from the stacking direction, and comprises a pair of second notches in which a pair of corners of the rectangle corresponding to the first notches are cut out in a chamfered manner, and the terminals are arranged in each of the pair of second notches.

[0010] According to the energy storage element described in (1), since the terminals are located in the second notch of the container, the busbar can be placed in the space outside the container formed by the second notch and connected to the terminals. Therefore, the busbar can be contained within the rectangle, and the space consumed outside the container by the busbar can be suppressed. As a result, the volumetric energy density of the energy storage element system can be increased.

[0011] (2) In the energy storage element described in (1) above, the pair of tabs may be arranged between the pair of terminals.

[0012] According to the energy storage element described in (2), since a pair of tabs are positioned between a pair of terminals, the distance between the tabs and terminals can be shortened. This allows the length of the current collector connecting the tabs and terminals to be shortened. Therefore, the electrical resistance in the current collector can be reduced, and the connection work can be simplified.

[0013] (3) In the energy storage element described in (1) or (2) above, the electrode body may be formed by winding the electrode plate and comprises a flat portion and a pair of curved portions sandwiching the flat portion, and the electrode body may be arranged in a position in which the winding axis faces between the pair of terminals.

[0014] According to the energy storage element described in (3), the electrode body is positioned such that the winding axis faces between the pair of terminals. Therefore, when the energy storage element is installed with the terminals facing upwards, the gas generated by the side reaction can be discharged through the electrode plates into the upper space of the energy storage element. This suppresses the occurrence of lithium electrodeposition caused by the gas, and makes it possible to extend the lifespan of the energy storage element.

[0015] (4) In the energy storage element described in (3) above, the pair of wall portions facing the pair of curved portions in the container may be curved wall portions.

[0016] (4) According to the energy storage element described above, in the container, the pair of wall portions facing the pair of curved portions are curved walls, so that the inner surface of the curved walls can be fitted along the curved portions. This makes it possible to uniformly pressurize the curved portions from the curved walls, and prevents deformation of the electrode body due to charging and discharging.

[0017] (Embodiments) The energy storage element according to an embodiment of the present invention will be described below with reference to the drawings. The embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection configurations of components, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples and are not intended to limit the present invention. In addition, dimensions, etc., are not strictly illustrated in each figure. Furthermore, the same or similar components are denoted by the same reference numerals in each figure. The names of each component (each component) in this embodiment are those of this embodiment and may differ from the names of each component (each component) in the background art.

[0018] In the following description and drawings, the direction in which the pair of electrode terminals are aligned and the longitudinal direction of the container are defined as the X-axis direction, the thickness direction of the container and the thickness direction of the electrode body are defined as the Y-axis direction, and the direction in which the container body and lid are aligned and the electrode body and lid are aligned are defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Depending on the orientation of the energy storage element, the Z-axis direction may not be vertical, but for the sake of explanation, the Z-axis direction will be described as vertical.

[0019] In the following explanation, for example, the "X-axis positive direction" refers to the direction of the X-axis arrow, and the "X-axis negative direction" refers to the opposite direction. The same applies to the Y-axis and Z-axis directions. When simply referred to as "X-axis direction," it means either the bidirectional or unidirectional direction parallel to the X-axis. The same applies to the terminology related to the Y-axis and Z-axis.

[0020] Furthermore, expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where the direction or orientation is not strictly accurate. For example, two directions being orthogonal does not only mean that the two directions are perfectly orthogonal, but also that they are substantially orthogonal, i.e., include a difference of a few percent. In the following explanation, when "insulation" is used, it means "electrical insulation." The volume resistivity of an insulating material is 1 × 10⁻⁶ ６ Preferably Ωm or more, 1 × 10 ７ Ωm or greater is more preferable, 1 × 10 １０ A value of Ωm or greater is even more preferable.

[0021] [Energy Storage Element] A general description of the energy storage element 10 according to the embodiment will be given. Figure 1 is a perspective view showing the external appearance of the energy storage element 10 according to the embodiment. Figure 2 is an exploded perspective view showing the components arranged inside the container 100 of the energy storage element 10 according to the embodiment.

[0022] The energy storage element 10 is a secondary battery, more specifically a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is used as a battery for propulsion or engine starting of mobile vehicles such as automobiles, motorcycles, watercraft, ships, snowmobiles, agricultural machinery, construction machinery, automated guided vehicles (AGVs), aircraft, or railway vehicles for electric railways. Examples of automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicles. Examples of railway vehicles for electric railways include electric trains, monorails, maglev trains, and hybrid trains equipped with both diesel engines and electric motors. The energy storage element 10 can also be used as a stationary battery for household or commercial use.

[0023] The energy storage element 10 is a secondary battery (single cell) capable of charging and discharging electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. 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 a capacitor. The energy storage element 10 may be a primary battery instead of a secondary battery. Furthermore, the energy storage element 10 may be a battery using a solid electrolyte.

[0024] As shown in Figure 1, the energy storage element 10 comprises a container 100, a pair of electrode terminals 200 (positive and negative), and a pair of external gaskets 500. As shown in Figure 2, a pair of current collectors 300 (positive and negative), a pair of internal gaskets 600, and electrode bodies 400 are housed inside the container 100.

[0025] In addition to the above-mentioned components, the energy storage element 10 may also include a spacer positioned to the side of the electrode body 400, and an insulating film that encloses the electrode body 400, etc. An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but this is not shown in the illustration. There are no particular restrictions on the type of electrolyte as long as it does not impair the performance of the energy storage element 10, and various types can be selected.

[0026] [Electrode Body] The electrode body 400 is an energy storage element (power generation element) that can store electricity. The electrode body 400 is a laminated electrode body in which a plurality of electrode plates and a plurality of separators are stacked in the Y-axis direction (stacking direction). The electrode body 400 comprises an electrode body main body 410 and a pair of tab portions 420 protruding from one side of the electrode body main body 410. The electrode body main body 410 has a rectangular shape when viewed from the Y-axis direction, and all corners of the rectangle are chamfered cutouts 401. In other words, the electrode body main body 410 has four cutouts 401, and each cutout 401 has a planar inclined surface that is inclined with respect to the XY plane. The electrode body main body 410 has an octagonal shape that extends in the X-axis direction when viewed in the Y-axis direction.

[0027] The pair of tab portions 420 are a group of tabs that protrude in the Z-axis direction from one side of the electrode body 410 in the Z-axis direction, with one tab portion 420 having the polarity of the positive electrode and the other tab portion 420 having the polarity of the negative electrode. Each tab portion 420 is rectangular in shape when viewed in the Y-axis direction.

[0028] The electrode body 400 consists of multiple electrode plates, including positive electrode plates and negative electrode plates, which are repeatedly and alternately stacked in the Y-axis direction with a separator in between. The positive electrode plate is an electrode plate on which a positive electrode active material layer is formed on at least one of the front and back surfaces of a current collector foil, which is a metal foil. In the positive electrode plate, the portion corresponding to the electrode body 410 has a positive electrode active material layer, and a positive electrode tab, which constitutes one tab portion 420, protrudes from one side in the Z-axis positive direction. The positive electrode tab is a portion where the positive electrode active material layer is not formed and the current collector foil is exposed. One tab portion 420 is formed by stacking the positive electrode tabs of multiple positive electrode plates.

[0029] The negative electrode plate is an electrode plate in which a negative electrode active material layer is formed on at least one of the front and back surfaces of a current collector foil, which is a metal foil. In the negative electrode plate, the portion corresponding to the electrode body 410 has a negative electrode active material layer, and a negative electrode tab, which constitutes the other tab portion 420, protrudes from one side in the positive Z-axis direction. The negative electrode tab is a portion in which the positive electrode active material layer is not formed and the current collector foil is exposed. The other tab portion 420 is formed by stacking the negative electrode tabs of multiple negative electrode plates.

[0030] The positive electrode current collector foil is made of aluminum or an aluminum alloy, etc. The negative electrode current collector foil is made of copper or a copper alloy, etc. The positive electrode active material layer includes a positive electrode active material, a binder, and a conductive material, etc. The negative electrode active material layer includes a negative electrode active material, a binder, and a thickener, etc. As the positive electrode active material and the negative electrode active material, any known material can be used as long as it is a material capable of intercalating and deintercalating charge transport ions.

[0031] As the positive electrode active material, LiNiMO ２ It is preferable to use Ni-containing layered lithium transition metal oxides such as (where M is one or more metal elements selected from Mn, Co, Al, etc.). As the negative electrode active material, it is preferable to use carbon materials such as graphite, or silicon compounds such as silicon, silicon oxide, silicon-carbon composites, or mixtures thereof.

[0032] The separator is a microporous sheet made of resin. Any known material can be used as the separator material, as long as it does not impair the performance of the energy storage element 10. For example, a woven fabric, nonwoven fabric, or a synthetic resin microporous membrane made of polyolefin resin such as polyethylene, which is insoluble in organic solvents, can be used as the separator.

[0033] [Container] The container 100 houses a pair of current collectors 300, an internal gasket 600, and an electrode body 400, and also holds a pair of electrode terminals 200 and an external gasket 500. The container 100 has a rectangular shape when viewed from the Y-axis direction, and all of the corners of the rectangle are second notches 101 that are cut out in a chamfered manner. In other words, each second notch 101 corresponds to each first notch 401 of the electrode body 400. Of the four second notches 101, at least one of the pair of second notches 101 in the Z-axis negative direction may have a gas discharge valve formed therein to release pressure when the pressure inside the container 100 rises. In this case, the gas flow path discharged from the gas discharge valve can be contained within the rectangle that is the basis of the container 100. This makes it possible to reduce the installation space for the gas flow path.

[0034] The container 100 comprises a container body 110 having a bottom and being open in the Z-axis positive direction, and a lid 120 that closes the opening of the container body 110. The container body 110 comprises a bottom wall 111 and a peripheral wall portion 112. The bottom wall 111 is a plate-like portion with the X-axis direction as its longitudinal direction. Specifically, the middle portion of the bottom wall 111 in the X-axis direction is a flat plate portion parallel to the XY plane, and both ends of the bottom wall 111 in the X-axis direction are flat plate portions that are inclined toward the Z-axis positive direction as they move away from the middle portion.

[0035] The peripheral wall portion 112 is formed in an annular shape with its axial direction being the Z-axis direction, and comprises a pair of first wall portions 113 facing each other in the Y-axis direction and a pair of second wall portions 114 facing each other in the X-axis direction. Each first wall portion 113 is a flat plate formed in an octagonal shape in plan view. Each second wall portion 114 is a flat plate formed in a rectangular shape in plan view.

[0036] The lid 120 is a plate with its longitudinal direction in the X-axis direction. Specifically, the middle portion 121 of the lid 120 in the X-axis direction is a flat plate portion parallel to the XY plane, and one end 122 and the other end 123 of the lid 120 in the X-axis direction are flat plate portions that are inclined toward the XY plane toward the negative Z-axis direction as they move away from the middle portion 121. Through holes 124 are formed in the one end 122 and the other end 123 of the lid 120. Although not shown in the figures, an electrolyte injection port is formed in the middle portion 121 of the lid 120. The electrolyte injection port is a part for injecting electrolyte into the container 100 during the manufacturing of the energy storage element 10, and is closed after injection.

[0037] After the electrode body 400 and the like are placed inside the container 100, the inside of the container 100 is sealed by joining the lid 120 and the container body 110 by welding or other means. The material of the container body 110 and the lid 120 is not particularly limited, but it is preferable that they be made of a weldable metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet.

[0038] [Current Collectors] Each current collector 300 is a conductive member positioned between the electrode body 400 and the lid 120 and individually connected to a pair of tab portions 420 of the electrode body 400. The current collector 300 can be made of aluminum, an aluminum alloy, copper, or a copper alloy. Each current collector 300 is integrally provided with a flat plate-shaped first current collector portion 310 and a second current collector portion 320, which are bent at the boundary. The first current collector portion 310 is joined (welded) to the tab portion 420 of the electrode body 400 in a state parallel to the XY plane. A through hole 324 is formed in the second current collector portion 320. The second current collector portion 320 is positioned along the inclined surface of the first cutout portion 401 of the electrode body 400. In this way, the second current collector portion 320 is positioned along the first cutout portion 401 of the container 100.

[0039] [Internal Gasket and External Gasket] Each internal gasket 600 is a plate-shaped and rectangular insulating seal member that is disposed between the lid body 120 and the current collector 300 to insulate and seal them. Specifically, the internal gasket 600 is disposed between one end portion 122 or the other end portion 123 of the lid body 120 and the second current collecting portion 320 of the current collector 300. A through-hole 604 is formed in the internal gasket 600.

[0040] [External Gasket] Each external gasket 500 is a plate-shaped and rectangular insulating seal member that is disposed between the lid body 120 and the electrode terminal 200 to insulate and seal them. Specifically, it is disposed between one end portion 122 or the other end portion 123 of the lid body 120 and the electrode terminal 200. A through-hole 504 is formed in the external gasket 500.

[0041] The external gasket 500 and the internal gasket 600 are formed of a resin having electrical insulation properties, 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.

[0042] [Electrode Terminal] The electrode terminal 200 is a terminal electrically connected to the electrode body 400 via the current collector 300. That is, the positive electrode terminal 200 is electrically connected to one tab portion 420 of the electrode body 400 via the current collector 300, and the negative electrode terminal 200 is electrically connected to the other tab portion 420 of the electrode body 400 via the current collector 300. The electrode terminal 200 includes a flat terminal body 210 and a shaft portion 220 protruding from the terminal body 210.

[0043] The electrode terminal 200 is inserted and caulked into the through holes 504, 124, 604, and 324 of the external gasket 500, the lid body 120, the internal gasket 600, and the current collector 300 in a state where the terminal body 210 is disposed at one end portion 122 or the other end portion 123 of the lid body 120. As a result, the electrode terminal 200 is electrically connected to the electrode body 400 via the current collector 300 in a state where it is disposed in each of the second notch portions 101 in the +Z-axis direction in the container 100. After the connection, the pair of tab portions 420 of the electrode body 400 are folded and disposed between the pair of electrode terminals 200 in the X-axis direction.

[0044] [Effects, etc.] As described above, according to the present embodiment, since the electrode terminal 200 is disposed in the second notch portion 101 of the container 100, a bus bar can be disposed in the space outside the container 100 formed by the second notch portion 101 and connected to the electrode terminal 200. Therefore, the bus bar can be accommodated within the reference rectangle of the container 100, and the consumption space outside the container 100 due to the bus bar can be suppressed. By these means, the volume energy density can be increased when the power storage element 10 is incorporated into a system.

[0045] Since the pair of tab portions 420 are disposed between the pair of electrode terminals 200, the distance between the tab portion 420 and the electrode terminal 200 can be shortened. As a result, the length of the current collector 300 that connects the tab portion 420 and the electrode terminal 200 can be shortened. Therefore, the electrical resistance in the current collector can be reduced, and the connection work can also be simplified.

[0046] (Modification) Hereinafter, each modification of the above embodiment will be described. In the following description, the same reference numerals may be given to the same parts as those in the above embodiment or other modifications, and the description thereof may be omitted.

[0047] [Modification 1] In the above embodiment, an energy storage element 10 equipped with a stacked electrode body 400 was exemplified. In this modification 1, an energy storage element 10A equipped with a wound electrode body 400a will be described. Figure 3 is an exploded perspective view of the energy storage element 10A according to modification 1. As shown in Figure 3, the electrode body 400a is formed by winding a separator between a positive electrode plate and a negative electrode plate. The electrode body 400a comprises an electrode body main body 410a and a pair of tab portions 420 protruding from one side of the electrode body main body 410a. The electrode body main body 410a has a rectangular shape when viewed from the Y-axis direction, and all corners of the rectangle are chamfered and cut out, forming a first cutout portion 401a. The electrode body main body 410a has an oval outer shape extending in the X-axis direction when viewed from the Z-axis direction. For this reason, the electrode body main body 410a comprises a flat portion 411a and a pair of curved portions 412a sandwiching the flat portion 411a. The flat portion 411a is a flat area overall. Since the flat portion 411a is the main part of the electrode body 410a, the stacking direction (Y-axis direction) of the positive electrode plate and negative electrode plate in this flat portion 411a can also be called the overall stacking direction of the electrode body 400a. Each curved portion 412a is curved so as to be convex outward when viewed in the Z-axis direction. Each curved portion 412a has a single cutout portion 401a formed therein.

[0048] Specifically, the electrode body 400a is constructed by stacking a long positive electrode plate and a long negative electrode plate with a separator in between, and these are wound around an axis parallel to the Z-axis direction, with a winding axis W. The electrode body 400a is positioned such that the winding axis faces between the pair of electrode terminals 200.

[0049] Since the electrode body 400a is positioned such that the winding axis W faces between the pair of electrode terminals 200, when the energy storage element 10 is installed with the electrode terminals 200 facing upward as shown in Figure 1, the gas generated by the side reaction can be discharged through the space between the electrode plates of the electrode body 400a into the upper space of the energy storage element 10A. This suppresses the occurrence of lithium electrodeposition caused by the gas, and extends the lifespan of the energy storage element 10A.

[0050] [Modification 2] In Modification 1 above, an energy storage element 10A was exemplified, comprising an electrode body 400a in which all four corners are first cutouts 401a, and a container 100 in which all four corners are second cutouts 101. However, in Modification 2, an energy storage element 10B is exemplified, comprising an electrode body 400b in which only a pair of adjacent corners are first cutouts 401b, and a container 100b in which only a pair of adjacent corners are second cutouts 101b. Figure 4 is an exploded perspective view of the energy storage element 10B according to Modification 2.

[0051] As shown in Figure 4, in the electrode body 410b of the electrode body 400b, only the pair of corners in the Z-axis positive direction out of the four corners of the reference rectangle are the first notches 401b. Each of the first notches 401b is formed only at the ends in the Z-axis positive direction in each curved portion 412b of the electrode body 410b. On the other hand, in the container 100b, only the pair of corners in the Z-axis positive direction out of the four corners of the reference rectangle are the second notches 101b.

[0052] [Modification 3] In Modification 1 above, an energy storage element 10A was illustrated in which each second wall portion 114 of the container 100 is a flat plate. However, in Modification 3, an energy storage element 10C is illustrated in which each second wall portion 114c of the container 100c is a curved wall portion. Figure 5 is an exploded perspective view of the energy storage element 10C according to Modification 3.

[0053] As shown in Figure 5, in the container body 110c of the container 100c provided in the energy storage element 10C, each second wall portion 114c is a curved wall portion that is convex outward when viewed in the Z-axis direction. Each second wall portion 114c is shaped to conform to each curved portion 412a of the electrode body 400a.

[0054] Thus, in the container 100c, since the pair of second wall portions 114c facing the pair of curved portions 412a are curved walls, the inner surface of the second wall portions 114c can be fitted along the curved portions 412a. This makes it possible to uniformly pressurize the curved portions 412a from the second wall portions 114c, and prevents deformation of the electrode body 400a due to charging and discharging.

[0055] (Other) The above describes the method for manufacturing an energy storage element according to embodiments of the present invention (including its modifications; the same applies hereinafter), but the present invention is not limited to the above embodiments. The embodiments disclosed herein are illustrative in all respects, and the scope of the present invention includes all modifications in the sense and scope equivalent to the claims. Forms constructed by arbitrarily combining the components included in the above embodiments and their modifications are also included in the scope of the present invention.

[0056] The energy storage element 10 may be used in an energy storage device. In this case, the technology of the present invention only needs to be applied to at least one energy storage element 10 provided in the energy storage device. An energy storage device can be rephrased as a system equipped with at least one energy storage element 10. Figure 6 is a schematic diagram showing an energy storage device 900 equipped with an energy storage element 10 according to an embodiment. As shown in Figure 6, a plurality of energy storage units 910 are arranged inside the energy storage device 900. An energy storage unit 910 is composed of a plurality of electrically connected energy storage elements 10. The energy storage device 900 may be equipped with a busbar (not shown) that electrically connects a plurality of energy storage elements 10, or a busbar (not shown) that electrically connects a plurality of energy storage units 910, etc. An energy storage unit 910 or an energy storage device 900 may be equipped with a state monitoring device (not shown) that monitors the state of one or more energy storage elements 10. An energy storage device 900 may be equipped with only one energy storage unit 910. In other words, an energy storage unit 910 may be referred to as an energy storage device.

[0057] This invention can be applied to energy storage elements such as lithium-ion secondary batteries.

[0058] 10, 10A, 10B, 10C Energy storage element 100, 100b, 100c Container 101, 101b Second notch 110, 110c Container body 111 Bottom wall 112 Peripheral wall 113 First wall 114, 114c Second wall 120 Lid 121 Intermediate part 122 One end 123 Other end 124, 324, 504, 604 Through hole 200 Electrode terminal (terminal) 210 Terminal body 220 Shaft part 300 Current collector 310 First current collector 320 Second current collector 400, 400a, 400b Electrode body 401, 401a, 401b First notch 410, 410a, 410b Electrode body body 411a Flat section 412a, 412b Curved section 420 Tab section 500 External gasket 600 Internal gasket 900 Energy storage device 910 Energy storage unit W Winding shaft

Claims

1. An energy storage element comprising: an electrode body in which electrode plates are stacked; a container for housing the electrode body; and a pair of terminals electrically connected to the electrode body and located outside the container, wherein the electrode body comprises an electrode body body and a pair of tab portions protruding from one side of the electrode body body, the electrode body body is rectangular in shape when viewed from the stacking direction of the electrode plates, and comprises a pair of first notches in which a pair of adjacent corners of the rectangle are chamfered and notched, the container is rectangular in shape when viewed from the stacking direction, and comprises a pair of second notches in which a pair of corners of the rectangle corresponding to the first notches are chamfered and notched, and the terminals are located in each of the pair of second notches.

2. The energy storage element according to claim 1, wherein the pair of tab portions are arranged between the pair of terminals.

3. The electrode body is formed by winding the electrode plate and comprises a flat portion and a pair of curved portions sandwiching the flat portion, and the electrode body is arranged in a position in which the winding axis faces between the pair of terminals, as described in claim 1 or 2.

4. The energy storage element according to claim 3, wherein the pair of wall portions facing the pair of curved portions in the container are curved wall portions.

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