Energy storage element

Abstract

In an electricity storage element 10 provided with an electrode body 700: the electrode body 700 is formed by winding a positive electrode plate 740 and a negative electrode plate 750 around a winding axis L; the positive electrode plate 740 includes a positive electrode active material portion 743 in which a positive electrode active material layer 742 is formed on a positive electrode substrate 741; the negative electrode plate 750 includes a negative electrode active material portion 753 in which a negative electrode active material layer 752 is formed on a negative electrode substrate 751; and a through hole 730 is formed in at least one of the positive electrode active material portion 743 and the negative electrode active material portion 753.

Description

Technical Field

[0001] The present invention relates to a power storage element including an electrode body.

Background Art

[0002] Conventionally, a power storage element including a wound electrode body formed by winding a positive electrode plate and a negative electrode plate is widely known. Patent Document 1 discloses a battery (power storage element) including an electrode group (electrode body) formed by winding a positive electrode (positive electrode plate) and a negative electrode (negative electrode plate), and an exterior member (container) in which an electrolyte injection port is formed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional power storage element, during manufacturing, an electrolyte is injected from an injection port formed in a container to impregnate the electrolyte into the electrode body or to degas the gas from the electrode body. However, when the electrode body is of a wound type as in the above conventional power storage element, since there are few regions through which the electrolyte or gas can pass between the inside and the outside of the electrode body, it may be difficult to impregnate the electrolyte into the electrode body or to degas the gas from the electrode body.

[0005] An object of the present invention is to provide a power storage element that can easily impregnate an electrolyte into an electrode body or degas a gas from the electrode body.

Means for Solving the Problems

[0006] An energy storage element according to one aspect of the present invention is an energy storage element comprising an electrode body, wherein the electrode body is formed by winding a positive electrode plate and a negative electrode plate around a winding axis, the positive electrode plate has a positive electrode active material portion in which a positive electrode active material layer is formed on a positive electrode substrate, and the negative electrode plate has a negative electrode active material portion in which a negative electrode active material layer is formed on a negative electrode substrate, and a through hole is formed in at least one of the positive electrode active material portion and the negative electrode active material portion.

[0007] This invention can be realized not only as such an energy storage element, but also as an electrode body. [Effects of the Invention]

[0008] The energy storage element of the present invention facilitates the impregnation of the electrode body with an electrolyte solution, or the degassing of gas from the electrode body. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a perspective view showing the external appearance of an energy storage element according to an embodiment. [Figure 2] Figure 2 is an exploded perspective view showing the individual components of the energy storage element according to the embodiment. [Figure 3] Figure 3 is a perspective view showing the configuration of the electrode body according to the embodiment. [Figure 4] Figure 4 is a perspective view and a cross-sectional view showing the configuration of the electrode body according to the embodiment. [Figure 5] Figure 5 is a front view and a cross-sectional view showing the configuration of the through-holes in the electrode body according to the embodiment. [Figure 6] Figure 6 is a front view and a cross-sectional view showing the configuration of the through-hole in the electrode body according to a modified example 1 of the embodiment. [Figure 7] Figure 7 is a perspective view showing the configuration of the electrode body according to a modified example 2 of the embodiment. [Figure 8] Figure 8 is a perspective view showing the configuration of the electrode body according to a modified example 3 of the embodiment. [Figure 9] Figure 9 is a perspective view showing the configuration of the electrode body according to a modified example 4 of the embodiment. [Modes for carrying out the invention]

[0010] An energy storage element according to one aspect of the present invention is an energy storage element comprising an electrode body, wherein the electrode body is formed by winding a positive electrode plate and a negative electrode plate around a winding axis, the positive electrode plate has a positive electrode active material portion in which a positive electrode active material layer is formed on a positive electrode substrate, and the negative electrode plate has a negative electrode active material portion in which a negative electrode active material layer is formed on a negative electrode substrate, and a through hole is formed in at least one of the positive electrode active material portion and the negative electrode active material portion.

[0011] According to this, in an energy storage element, a through-hole is formed in at least one of the positive electrode active material portion of the positive electrode plate and the negative electrode active material portion of the negative electrode plate in an electrode body in which a positive electrode plate and a negative electrode plate are wound around a winding axis. In this way, a through-hole is formed in at least one of the positive electrode active material portion and the negative electrode active material portion of the wound electrode body. As a result, even if the electrode body is of the wound type, the electrolyte or gas can easily pass between the inside and outside of the electrode body through the through-hole, making it easier to impregnate the electrode body with electrolyte or to degas from the electrode body (including the discharge of gas generated during thermal runaway, etc.; the same applies hereinafter).

[0012] The through holes may be formed in a plurality of locations in a direction along the winding axis.

[0013] According to this, by forming multiple through-holes in the electrode body that are aligned along the winding axis, the electrolyte or gas can easily pass between the inside and outside of the electrode body through these through-holes along the winding axis. This makes it easier to impregnate the electrode body with electrolyte or to degas the electrode body with gas.

[0014] The electrode body has a curved portion and a flat portion formed by winding the positive electrode plate and the negative electrode plate around the winding shaft, and the through hole may be formed at least one of the positions in the curved portion close to the flat portion and the position in the flat portion close to the curved portion.

[0015] In an electrode body having a bent portion and a flat portion, forming through holes in the bent portion has a greater effect of facilitating the impregnation of the electrolyte into the electrode body or the degassing of gas from the electrode body. However, if the through holes are formed at a position where the bending of the bent portion is sharp, there is a risk that the active material layer around the through holes will peel off or be damaged when the electrode plate is wound. Therefore, the through holes are formed near the boundary between the bent portion and the flat portion (at least one of a position close to the flat portion in the bent portion and a position close to the bent portion in the flat portion). Thereby, through the through holes, while facilitating the impregnation of the electrolyte into the electrode body or the degassing of gas from the electrode body, damage to the active material layer around the through holes can be suppressed.

[0016] In the positive electrode active material portion, a positive electrode through hole as the through hole is formed, and in the negative electrode active material portion, a negative electrode through hole as the through hole is formed. The positive electrode through hole and the negative electrode through hole may be arranged at a position where at least a part thereof overlaps when viewed from the arrangement direction of the positive electrode through hole and the negative electrode through hole.

[0017] According to this, in the electrode body, the positive electrode through hole of the positive electrode active material portion and the negative electrode through hole of the negative electrode active material portion are arranged at a position where at least a part thereof overlaps. Thereby, the electrolyte or gas can easily pass between the inside and the outside of the electrode body through the positive electrode through hole and the negative electrode through hole, so that the impregnation of the electrolyte into the electrode body or the degassing of gas from the electrode body can be facilitated. [[ID=eleven]]

[0018] The electrode body further has a separator disposed between the positive electrode active material portion and the negative electrode active material portion. In the separator, a separator through hole may be formed at a position where at least a part thereof overlaps with the positive electrode through hole and the negative electrode through hole when viewed from the arrangement direction of the positive electrode through hole and the negative electrode through hole. [[ID=fourteen]]

[0019] According to this, in the electrode body, the separator has separator through-holes formed in it, at least a portion of which are positioned to overlap with the positive electrode through-hole and the negative electrode through-hole. By forming separator through-holes in the separator in this way, the electrolyte or gas can easily pass between the inside and outside of the electrode body through the separator through-holes. This makes it easier to impregnate the electrode body with electrolyte or to degas the electrode body with gas.

[0020] The positive electrode plate and the negative electrode plate are wound together so that a plurality of the positive electrode active material portions and a plurality of the negative electrode active material portions are stacked in the stacking direction, and a plurality of the positive electrode through holes and a plurality of the negative electrode through holes are formed in the plurality of positive electrode active material portions and a plurality of negative electrode through holes which are arranged continuously in the stacking direction.

[0021] According to this, in the electrode body, multiple positive electrode through-holes and multiple negative electrode through-holes are continuously formed in multiple positive electrode active material portions and multiple negative electrode active material portions. As a result, electrolyte or gas can easily pass between the inside and outside of the electrode body through the multiple positive electrode through-holes and multiple negative electrode through-holes, making it easier to impregnate the electrode body with electrolyte or to degas the electrode body with gas.

[0022] The through hole may have a shape in which the direction intersecting the direction along the winding axis is longer than the direction along the winding axis.

[0023] When the positive and negative electrode plates are wound in an electrode body, misalignment may occur in a direction intersecting the winding axis. Therefore, by forming the through-holes in a shape that is elongated in a direction intersecting the winding axis, the misalignment of the through-holes caused by winding the positive and negative electrode plates is suppressed. This prevents the misalignment of the through-holes from making it difficult for the electrolyte or gas to pass between the inside and outside of the electrode body, thus facilitating the impregnation of the electrolyte into the electrode body or the degassing of gas from the electrode body.

[0024] Furthermore, the device may include a container for housing the electrode body, and the through-hole may be formed in the portion of the electrode body that is on the bottom side of the container.

[0025] According to this method, by forming a through-hole in the bottom portion of the electrode body's container, the electrolyte can be retained in the center of the electrode body even when the amount of electrolyte in the container is small (for example, at the end of its lifespan).

[0026] The following description of an energy storage element according to an embodiment (including its modifications) of the present invention will be given with reference to the drawings. The embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement 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. Dimensions and other specifications are not strictly illustrated in each figure. In each figure, the same or similar components are denoted by the same reference numerals.

[0027] In the following description and drawings, the direction in which the pair of electrode terminals (positive and negative sides, hereinafter the same) of the energy storage element are aligned, the direction in which the pair of current collectors are aligned, the direction along the winding axis of the electrode body, the extension direction of the electrode body, or the opposing direction of the short sides of the container is defined as the X-axis direction. The direction in which the long sides of the container are aligned, or the thickness direction of the container is defined as the Y-axis direction. The direction in which the container body and lid of the container are aligned, or the vertical direction is 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 usage, the Z-axis direction may not be the vertical direction, but for the sake of explanation below, the Z-axis direction will be described as the vertical direction.

[0028] In the following explanation, 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. Expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where they are not strictly those directions or orientations. Two directions being orthogonal means not only that the two directions are perfectly orthogonal, but also that they are substantially orthogonal, i.e., that they may have a difference of, for example, a few percent.

[0029] (Embodiment) [1. General description of the energy storage element 10] First, a general description of the energy storage element 10 in this embodiment will be given using Figures 1 and 2. Figure 1 is a perspective view showing the external appearance of the energy storage element 10 according to this embodiment. Figure 2 is an exploded perspective view showing the individual components of the energy storage element 10 according to this embodiment.

[0030] The energy storage element 10 is a secondary battery (single cell) capable of charging and discharging electricity, 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, or railway vehicles for electric railways. Examples of automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and gasoline-powered automobiles. 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.

[0031] The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery, but may be a secondary battery other than a non-aqueous electrolyte secondary battery, or it may be a capacitor. The energy storage element 10 may not be a secondary battery, but a primary battery that allows the user to use the stored electricity without charging. The energy storage element 10 may be a pouch-type energy storage element. In this embodiment, the energy storage element 10 is shown in a flat rectangular parallelepiped shape (square), but the shape of the energy storage element 10 is not limited to a rectangular parallelepiped shape, but may be a polygonal prism shape, an oblong cylinder shape, an elliptical cylinder shape, or a cylinder shape, etc.

[0032] As shown in Figure 1, the energy storage element 10 comprises a container 100, a pair of electrode terminals 300 (positive and negative sides), and a pair of upper gaskets 400 (positive and negative sides). As shown in Figure 2, a pair of lower gaskets 500 (positive and negative sides), a pair of current collectors 600 (positive and negative sides), and an electrode body 700 are housed inside the container 100. 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. In addition to the above components, spacers placed to the side or below the electrode body 700, insulating films that enclose the electrode body 700, etc., may also be arranged.

[0033] The container 100 is a rectangular parallelepiped (square or box-shaped) case having a container body 110 with an opening formed therein and a lid 120 that closes the opening of the container body 110. The container body 110 is a rectangular cylindrical member with a bottom that constitutes the main body of the container 100. The container body 110 has a pair of flat, rectangular short sidewalls on both sides (short sides) in the X-axis direction, a pair of flat, rectangular long sidewalls on both sides (long sides) in the Y-axis direction, and a flat, rectangular bottom wall on the Z-axis negative side. The lid 120 is a rectangular plate-shaped member that constitutes the lid of the container 100 and is arranged extending in the X-axis direction in the Z-axis positive direction of the container body 110.

[0034] With this configuration, the container 100 is structured so that after the electrode body 700 and the like are housed inside the container body 110, the container body 110 and the lid 120 are joined by welding or the like to seal the inside. The material of the container 100 (container body 110 and lid 120) is not particularly limited, but it is preferable that it be a weldable metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet.

[0035] The lid 120 has a liquid injection section 130 and a gas discharge valve 140. The gas discharge valve 140 is a safety valve that releases pressure when the pressure inside the container 100 rises excessively. The liquid injection section 130 is a part for injecting electrolyte into the container 100 during the manufacture of the energy storage element 10. Specifically, the liquid injection section 130 is used during the manufacture of the energy storage element 10 to inject electrolyte into the container 100 to impregnate the electrode body 700 with electrolyte and to degas the gas from inside the electrode body 700. In this embodiment, the liquid injection section 130 is located near the negative X-axis and in the center of the Y-axis direction of the lid 120, but the liquid injection section 130 may be located at any position on the lid 120.

[0036] The liquid injection section 130 has a liquid injection port 131 and a liquid injection stopper 132. The liquid injection port 131 is, for example, a circular through-hole formed in the lid 120 for injecting electrolyte into the container 100. The liquid injection stopper 132 is a member that closes the liquid injection port 131. Specifically, the liquid injection stopper 132 is a closing member (lid member) that is joined to the lid 120 to close the liquid injection port 131 after the electrolyte has been injected into the container 100 from the liquid injection port 131 during the manufacturing of the energy storage element 10. The material of the liquid injection stopper 132 is not particularly limited, but any metal or the like that can be used for the container 100 (lid 120) can be used. In particular, the liquid injection stopper 132 is formed of a material that can be welded to the lid 120, such as the same material as the lid 120.

[0037] The electrode terminals 300 are terminal members (positive and negative terminals) that are electrically connected to the electrode body 700 via the current collector 600. In other words, the electrode terminals 300 are metallic members that guide the electricity stored in the electrode body 700 to the external space of the energy storage element 10 and introduce electricity into the internal space of the energy storage element 10 to store electricity in the electrode body 700. The electrode terminals 300 are made of a conductive material such as aluminum, aluminum alloy, copper, or copper alloy. The electrode terminals 300 are connected (joined) to the current collector 600 by crimping or welding, and are attached to the cover 120.

[0038] The current collector 600 is positioned on both sides of the electrode body 700 in the X-axis direction and is connected (joined) to the electrode body 700 and the electrode terminal 300. It is a current collecting member (positive electrode current collector and negative electrode current collector) that has conductivity and rigidity to electrically connect the electrode body 700 and the electrode terminal 300. Specifically, the current collector 600 is connected (joined) to the end portion 720 of the electrode body 700 (described later) by welding or crimping, and as described above, it is connected (joined) to the electrode terminal 300 by crimping or welding and fixed to the cover body 120. The material of the current collector 600 is not particularly limited, but the current collector 600 on the positive electrode side is formed of a conductive material such as aluminum or an aluminum alloy, similar to the positive electrode base material 741 of the electrode body 700 (described later), and the current collector 600 on the negative electrode side is formed of a conductive material such as copper or a copper alloy, similar to the negative electrode base material 751 of the electrode body 700 (described later).

[0039] The upper gasket 400 is a plate-shaped, rectangular insulating sealing member that is placed between the lid 120 of the container 100 and the electrode terminal 300, and insulates and seals the space between the lid 120 and the electrode terminal 300. The lower gasket 500 is a plate-shaped, rectangular insulating sealing member that is placed between the lid 120 and the current collector 600, and insulates and seals the space between the lid 120 and the current collector 600. The upper gasket 400 and the lower gasket 500 are formed from electrically insulating resins 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 composite materials thereof.

[0040] The electrode body 700 is an electrical storage element (power generation element) formed by winding electrode plates, capable of storing electricity. The electrode body 700 has a long shape extending in the X-axis direction, and has an oval shape (elongated cylindrical shape) when viewed from the X-axis direction. The electrode body 700 has a shape that extends in the X-axis direction, for example, 300 mm or more, specifically about 500 mm to 1500 mm. The electrode body 700 has an electrode body main body portion 710 and ends 720 that protrude from the electrode body main body portion 710 on both sides in the X-axis direction, and as described above, the ends 720 are connected (joined) to the current collector 600. A through hole 730 is formed in the electrode body main body portion 710. The configuration of such an electrode body 700 will be described in detail below.

[0041] [2. Description of the configuration of electrode body 700] Figure 3 is a perspective view showing the configuration of the electrode body 700 according to this embodiment. Specifically, Figure 3 shows the configuration of the electrode body 700 with the winding state of the electrode plates partially unfolded. Figure 4 is a perspective view and a cross-sectional view showing the configuration of the electrode body 700 according to this embodiment. Specifically, Figure 4(a) is a perspective view showing the configuration of the electrode body 700 after the electrode plates have been wound, and Figure 4(b) is a cross-sectional view showing the laminated state of the electrode plates by enlarging a part of the cross section of the electrode body 700.

[0042] [2.1 General Description of Electrode Body 700] As shown in these figures, the electrode body 700 includes a positive electrode plate 740, a negative electrode plate 750, and separators 761 and 762.

[0043] The positive electrode plate 740 is an electrode plate in which a positive electrode active material layer 742 is formed on the surface of a positive electrode substrate 741, which is a long, strip-shaped metal foil made of aluminum or an aluminum alloy. The negative electrode plate 750 is an electrode plate in which a negative electrode active material layer 752 is formed on the surface of a negative electrode substrate 751, which is a long, strip-shaped metal foil made of copper or a copper alloy. As the positive electrode substrate 741 and the negative electrode substrate 751, any known material that is stable against oxidation-reduction reactions during charging and discharging can be used, such as nickel, iron, stainless steel, titanium, calcined carbon, conductive polymer, conductive glass, and Al-Cd alloy. As the positive electrode active material used in the positive electrode active material layer 742 and the negative electrode active material used in the negative electrode active material layer 752, any known material that is capable of intercalating and deintercalating lithium ions can be used.

[0044] As positive electrode active materials, polyanionic compounds such as LiMPO4, LiMSiO4, LiMBO3 (where M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), lithium titanate, LiMn2O4, and LiMn 1.5 Ni 0.5Spinel-type lithium manganese oxides such as O4, lithium transition metal oxides such as LiMO2 (where M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.) can be used. As negative electrode active materials, lithium metals, lithium alloys (lithium-silicon, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and lithium metal-containing alloys such as Wood's alloys), alloys capable of intercalating and deintercalating lithium, carbon materials (e.g., graphite, non-graphitizable carbon, easily graphitizable carbon, low-temperature calcined carbon, amorphous carbon, etc.), silicon oxides, metal oxides, lithium metal oxides (Li4Ti5O 12 Examples include polyphosphate compounds, or compounds of transition metals and group 14 to 16 elements, such as Co3O4 and Fe2P, which are generally called conversion negative electrodes.

[0045] Separators 761 and 762 are microporous sheets made of resin. Any known material can be used for separators 761 and 762, as long as it does not impair the performance of the energy storage element 10. As separators 761 and 762, woven fabrics, nonwoven fabrics, synthetic resin microporous membranes made of polyolefin resins such as polyethylene, which are insoluble in organic solvents, can be used. Alternatively, organic or inorganic materials may be coated onto separators 761 and 762, or added to their interior.

[0046] The electrode body 700 is formed by alternately stacking and winding a positive electrode plate 740, a negative electrode plate 750, and separators 761 and 762. In other words, the electrode body 700 is formed by stacking and winding the positive electrode plate 740, separator 761, negative electrode plate 750, and separator 762 in this order (see Figure 4(b), etc.). In this embodiment, the electrode body 700 is a wound type (so-called vertical winding type) electrode body formed by winding the positive electrode plate 740, negative electrode plate 750, etc., around a winding axis L extending in the X-axis direction. The winding axis L is a virtual axis that serves as the central axis when winding the positive electrode plate 740, negative electrode plate 750, etc., and in this embodiment, it is a straight line parallel to the X-axis direction that passes through the center of the electrode body 700.

[0047] Specifically, the electrode body 700 has a positive electrode plate 740 and a negative electrode plate 750 wound around each other via separators 761 and 762, offset from each other in the direction along the winding axis L (the X-axis direction; hereinafter also referred to as the winding axis direction). The positive electrode plate 740 and the negative electrode plate 750 have portions at their respective offset ends where the positive electrode active material layer 742 and the negative electrode active material layer 752 are not formed (coated), and the positive electrode base material 741 and the negative electrode base material 751 are exposed (non-active material layer portions). As a result, the electrode body 700 has a positive electrode end 720 at one end in the winding axis direction, where the non-active material layer portions of the positive electrode plate 740 are stacked and bundled, and a negative electrode end 720 at the other end in the winding axis direction, where the non-active material layer portions of the negative electrode plate 750 are stacked and bundled.

[0048] The end portion 720 is the portion where the positive electrode plate 740 or the negative electrode plate 750 is stacked in the stacking direction (Y-axis direction). In other words, the electrode body 700 has an electrode body main body portion 710 that constitutes the main body of the electrode body 700, and a pair of end portions 720 (positive electrode side and negative electrode side) that protrude from the electrode body main body portion 710 on both sides in the X-axis direction. The electrode body main body portion 710 is an elongated cylindrical portion (active material layer forming portion) formed by winding the portions of the positive electrode plate 740 and the negative electrode plate 750 on which the positive electrode active material layer 742 and the negative electrode active material layer 752 are formed (coated) with separators 761 and 762. As a result, the electrode body main body portion 710 has a pair of curved portions 711 on both sides in the Z-axis direction and a pair of flat portions 712 on both sides in the Y-axis direction (see Figure 4(a)). In other words, the electrode body 700 has a curved portion 711 and a flat portion 712, which are formed by winding the positive electrode plate 740 and the negative electrode plate 750 around the winding axis L.

[0049] The curved portion 711 is a curved part that extends in the X-axis direction, curved in the shape of a semicircular arc so as to project in the Z-axis direction when viewed from the X-axis direction, and is positioned opposite the bottom wall portion and lid portion 120 of the container body 110. In other words, the pair of curved portions 711 are curved parts that project on both sides in the Z-axis direction toward the bottom wall portion and lid portion 120 of the container body 110 when viewed from the X-axis direction. The flat portion 712 is a rectangular and flat part that connects the ends of the pair of curved portions 711, extending parallel to the XZ plane oriented in the Y-axis direction, and is positioned opposite the long side walls on both sides in the Y-axis direction of the container body 110. The curved shape of the curved portion 711 is not limited to a semicircular arc shape, but may be part of an ellipse, or any other shape. The flat portion 712 is not limited to having a flat outer surface facing the Y-axis direction, but may have a slightly concave or slightly bulging outer surface.

[0050] [2.2 Explanation of through hole 730] In the configuration described above, a through hole 730 is formed in the electrode body portion 710. The configuration of the through hole 730 will be described in detail below, with reference to Figure 5. Figure 5 is a front view and a cross-sectional view showing the configuration of the through hole 730 of the electrode body 700 according to this embodiment. Specifically, Figure 5(a) is a front view showing the configuration of the through hole 730 of the electrode body 700 when viewed from the front (Y-axis minus direction), and Figure 5(b) is a cross-sectional view showing the cross-section of Figure 5(a).

[0051] As shown in Figures 2 to 4, the through-holes 730 are formed at least one of the following locations: a position in the curved portion 711 close to the flat portion 712, and a position in the flat portion 712 close to the curved portion 711. In other words, the through-holes 730 are formed near the boundary between the curved portion 711 and the flat portion 712. To put it another way, the through-holes 730 are formed at least one of the ends of the curved portion 711 on the flat portion 712 side, and the ends of the flat portion 712 on the curved portion 711 side. For example, the position in the flat portion 712 close to the curved portion 711 (the end on the curved portion 711 side) refers to a portion within a range of approximately 10% to 25% of the total length of the flat portion 712 in the Z-axis direction, from the edge of the flat portion 712 on the curved portion 711 side. The same applies to the curved portion 711.

[0052] In this embodiment, the through-hole 730 is formed at a position close to the curved portion 711 in the positive Z-axis direction on the flat portion 712 in the negative Y-axis direction (the end on the side of the curved portion 711 in the positive Z-axis direction). As a result, the through-hole 730 is formed at the end of the electrode body 700 on the side of the lid 120. In other words, the through-hole 730 is formed at the part of the electrode body 700 on the side of the liquid injection portion 130. The end of the electrode body 700 on the side of the lid 120 (the part on the side of the liquid injection portion 130) refers to the part of the electrode body 700 that is within a range of approximately 10% to 25% of the total length of the electrode body 700 in the Z-axis direction, from the edge of the electrode body 700 in the positive Z-axis direction.

[0053] Multiple through-holes 730 are formed in a row along the winding axis L. In this embodiment, six through-holes 730 are arranged in the electrode body portion 710 at predetermined intervals in the X-axis direction. When the length of the electrode body 700 in the X-axis direction is about 1200 mm, the six through-holes 730 are arranged at intervals of about 200 mm. The interval between the through-holes 730 is not limited to 200 mm; they may be arranged at wider intervals of about 300 mm, or conversely, the interval between the through-holes 730 may be narrowed.

[0054] As shown in Figure 4(b), etc., the portion of the positive electrode plate 740 on which the positive electrode substrate 741 is coated with a positive electrode active material layer 742 is referred to as the positive electrode active material portion 743. The portion of the negative electrode plate 750 on which the negative electrode substrate 751 is coated with a negative electrode active material layer 752 is referred to as the negative electrode active material portion 753. In other words, the positive electrode substrate 741 and the positive electrode active material layer 742, excluding the portion included in the positive electrode end 720, are referred to as the positive electrode active material portion 743, and the negative electrode substrate 751, excluding the portion included in the negative electrode end 720, is referred to as the negative electrode active material portion 753. In other words, the portion of the positive electrode plate 740 other than the positive electrode base material 741 included in the positive electrode end 720 is referred to as the positive electrode active material portion 743, and the portion of the negative electrode plate 750 other than the negative electrode base material 751 included in the negative electrode end 720 is referred to as the negative electrode active material portion 753.

[0055] Specifically, in the electrode body 700, one layer of the positive electrode plate 740 in which the positive electrode active material layer 742 is formed on the positive electrode base material 741 is referred to as one positive electrode active material section 743. In the electrode body 700, one layer of the negative electrode plate 750 in which the negative electrode active material layer 752 is formed on the negative electrode base material 751 is referred to as one negative electrode active material section 753. In other words, by winding the positive electrode plate 740 and the negative electrode plate 750, a plurality of positive electrode active material sections 743 and a plurality of negative electrode active material sections 753 are stacked with separators 761 and 762 placed between the positive electrode active material sections 743 and the negative electrode active material sections 753. The electrode body main section 710 is formed by stacking these plurality of positive electrode active material sections 743, plurality of negative electrode active material sections 753, and separators 761 and 762.

[0056] Furthermore, a through hole 730 is formed in at least one of the positive electrode active material portion 743 and the negative electrode active material portion 753, which are located in at least one of the curved portion 711 and the flat portion 712 of the electrode body portion 710. In this embodiment, the through hole 730 is formed in both the positive electrode active material portion 743 and the negative electrode active material portion 753, which are located in the flat portion 712, as well as in the separators 761 and 762.

[0057] Specifically, as shown in Figure 5, the positive electrode active material portion 743 has a positive electrode through-hole 743a, which serves as a through-hole 730. The positive electrode through-hole 743a is a circular through-hole that penetrates the positive electrode active material portion 743 in the Y-axis direction. In other words, the positive electrode through-hole 743a is a circular through-hole that penetrates the positive electrode base material 741 and the two positive electrode active material layers 742 provided on both sides of the positive electrode base material 741 in the Y-axis direction. The negative electrode active material portion 753 has a negative electrode through-hole 753a, which serves as a through-hole 730. The negative electrode through-hole 753a is a circular through-hole that penetrates the negative electrode active material portion 753 in the Y-axis direction. In other words, the negative electrode through-hole 753a is a circular through-hole that penetrates the negative electrode base material 751 and the two negative electrode active material layers 752 provided on both sides of the negative electrode base material 751 in the Y-axis direction. However, the shapes of the positive electrode through-hole 743a and the negative electrode through-hole 753a are not limited to a circular shape and can be set as appropriate within a range that does not cause defects.

[0058] The positive electrode through-hole 743a and the negative electrode through-hole 753a are positioned so that at least a portion of them overlap when viewed from the direction of alignment (Y-axis direction) of the positive electrode through-hole 743a and the negative electrode through-hole 753a. In this embodiment, when viewed from the Y-axis direction, the negative electrode through-hole 753a is positioned so that it completely overlaps with the positive electrode through-hole 743a. In other words, when viewed from the Y-axis direction, the negative electrode through-hole 753a has a smaller shape than the positive electrode through-hole 743a and is positioned inside the positive electrode through-hole 743a. For example, the negative electrode through-hole 753a is a circular through-hole with a diameter of about 1 mm to 4 mm, and the positive electrode through-hole 743a is a circular through-hole with a diameter of about 1.5 mm to 5 mm. The diameters of the positive electrode through-hole 743a and the negative electrode through-hole 753a are preferable as they are small, but it is preferable that they be 1 mm or larger for ease of processing of the holes and for removing the electrode plate from the holes after processing. The diameters of the positive electrode through-hole 743a and the negative electrode through-hole 753a are examples and are not limited to the above range. The diameters of the positive electrode through-hole 743a and the negative electrode through-hole 753a can be set as appropriate. In particular, when the configuration is such that one through-hole completely overlaps the other when viewed from the direction of alignment of the positive electrode through-hole 743a and the negative electrode through-hole 753a, the diameters of the positive electrode through-hole 743a and the negative electrode through-hole 753a are determined considering the range in which misalignment may occur, taking into account the processing accuracy and winding accuracy. In this case, it is preferable that the diameter of the positive electrode through-hole 743a is larger than the diameter of the negative electrode through-hole 753a. For example, if it is determined that the diameter of the positive electrode through-hole 743a should be 4.0 mm or larger than the diameter of the negative electrode through-hole 753a from the viewpoint of processing accuracy and winding accuracy, then if the diameter of the negative electrode through-hole 753a is 1.0 mm, then it is preferable that the diameter of the positive electrode through-hole 743a be 5.0 mm or larger, which is the diameter of the negative electrode through-hole 753a plus an additional 4.0 mm.

[0059] The positive electrode through-hole 743a and the negative electrode through-hole 753a can be formed by laser processing (laser welding, laser cutting, etc.) before winding the positive electrode plate 740 and the negative electrode plate 750. The positive electrode through-hole 743a may be formed by forming (coating) a positive electrode active material layer 742 on a positive electrode substrate 741 that has a through-hole formed in advance, or by punching out the positive electrode through-hole 743a after forming (coating) the positive electrode active material layer 742 on the positive electrode substrate 741. The same applies to the negative electrode through-hole 753a. The positive electrode through-hole 743a and the negative electrode through-hole 753a can also be formed by press processing, but it is preferable to form them by laser processing in order to process small holes at high speed.

[0060] In this embodiment, the positive electrode plate 740 and the negative electrode plate 750 are wound together so that a plurality of positive electrode active material portions 743 and a plurality of negative electrode active material portions 753 are stacked in the stacking direction. In the flat portion 712, the plurality of positive electrode active material portions 743 and a plurality of negative electrode active material portions 753 are stacked in a direction perpendicular to the flat surface of the flat portion 712 (i.e., in the Y-axis direction). In the curved portion 711, the plurality of positive electrode active material portions 743 and a plurality of negative electrode active material portions 753 are stacked in a direction perpendicular to the curved surface of the curved portion 711 (i.e., in any direction from the Y-axis direction to the Z-axis direction). At this time, the plurality of positive electrode through holes 743a and a plurality of negative electrode through holes 753a are formed in the plurality of positive electrode active material portions 743 and a plurality of negative electrode through holes 753a which are arranged continuously in the stacking direction. In this embodiment, since multiple positive electrode through holes 743a and multiple negative electrode through holes 753a are formed in the flat portion 712, the stacking direction of the multiple positive electrode active material portions 743 and multiple negative electrode active material portions 753 can be defined as the Y-axis direction.

[0061] The multiple positive electrode through-holes 743a are formed such that they align after the positive electrode plate 740 and negative electrode plate 750 are wound, with the spacing increasing from the positive electrode active material portion 743 located in the innermost layer (innermost circumference) of the electrode body 700 to the positive electrode active material portion 743 located in the outermost layer (outermost circumference). The same applies to the negative electrode through-holes 753a.

[0062] The through-holes 730 are also formed in the outermost layer (outermost periphery) of the multiple positive electrode active material sections 743 and multiple negative electrode active material sections 753. When the negative electrode active material section 753 is positioned on the outermost layer (outermost periphery) of the electrode body 700, negative electrode through-holes 753a are also formed in the outermost negative electrode active material section 753. As a result, in the electrode body 700, the multiple positive electrode through-holes 743a and multiple negative electrode through-holes 753a are formed continuously from the outermost layer (outermost periphery) of the electrode body 700 to the innermost layer (innermost periphery) of the active material section. In other words, when viewed from the Y-axis direction, all negative electrode through-holes 753a formed in the multiple negative electrode active material sections 753 are positioned inside all positive electrode through-holes 743a formed in the multiple positive electrode active material sections 743.

[0063] Separator 761 has a separator through-hole 761a, which serves as a through-hole 730. Separator through-hole 761a is a circular through-hole that penetrates separator 761 in the Y-axis direction. Separator 762 has a separator through-hole 762a, which serves as a through-hole 730. Separator through-hole 762a is a circular through-hole that penetrates separator 762 in the Y-axis direction. In this embodiment, separator through-holes 761a and 762a are through-holes of the same shape and size, but they may be through-holes of different shapes or sizes.

[0064] The separator through-holes 761a and 762a are positioned such that, when viewed from the direction of alignment of the positive electrode through-hole 743a and the negative electrode through-hole 753a (Y-axis direction), at least a portion of them overlap with the positive electrode through-hole 743a and the negative electrode through-hole 753a. In this embodiment, when viewed from the Y-axis direction, the separator through-holes 761a and 762a are positioned so that they completely overlap with the positive electrode through-hole 743a and the negative electrode through-hole 753a. In other words, when viewed from the Y-axis direction, the separator through-holes 761a and 762a have a smaller shape than the positive electrode through-hole 743a and the negative electrode through-hole 753a, and are positioned inside the positive electrode through-hole 743a and the negative electrode through-hole 753a. From the viewpoint of machinability, the separator through-holes 761a and 762a are assumed to be circular through-holes with a diameter of approximately 0.5 mm to 3 mm. However, the diameters of the separator through-holes 761a and 762a are not limited to the above range and can be set appropriately within a range that allows for easy penetration of the electrolyte and does not cause defects. If machinability is not a consideration, the diameters of the separator through-holes 761a and 762a may be as small as 0.1 mm.

[0065] The separator through-holes 761a and 762a can be processed at high speed by irradiating the positions of the positive electrode through-holes 743a and negative electrode through-holes 753a with a laser after winding the positive electrode plate 740 and negative electrode plate 750. The separator through-holes 761a and 762a can also be formed by laser processing or press processing, etc., before winding the positive electrode plate 740 and negative electrode plate 750, similar to the positive electrode through-holes 743a and negative electrode through-holes 753a.

[0066] As a result, multiple separator through-holes 761a and 762a are formed in the separators 761 and 762 in a continuous manner in the Y-axis direction, along with multiple positive electrode through-holes 743a and multiple negative electrode through-holes 753a. In other words, multiple separator through-holes 761a and 762a are formed continuously from the outermost (outermost) separator 761 or 762 to the innermost (innermost) separator 761 or 762 in the electrode body 700. As a result, in the electrode body 700, when viewed from the Y-axis direction, all separator through-holes 761a and 762a formed in the separators 761 and 762 are located inside all positive electrode through-holes 743a and all negative electrode through-holes 753a. However, the configuration is not limited to the above, and it is not necessary to provide separator through-holes 761a and 762a in some of the innermost (innermost) layers.

[0067] [3. Explanation of Effects] As described above, according to the embodiment of the present invention, a through hole 730 is formed in at least one of the positive electrode active material portion 743 of the positive electrode plate 740 and the negative electrode active material portion 753 of the negative electrode plate 750 of the electrode body 700. In this way, a through hole 730 is formed in at least one of the positive electrode active material portion 743 and the negative electrode active material portion 753 of the wound electrode body 700. As a result, even if the electrode body 700 is of the wound type, electrolyte or gas can easily pass between the inside and outside of the electrode body 700 through the through hole 730. Therefore, impregnation of electrolyte into the electrode body 700 or degassing of gas (gas generated during release formation) from inside the electrode body 700 can be easily performed. Discharge of gas generated during thermal runaway, etc., can also be easily performed.

[0068] By forming a through-hole 730 in at least one of the positive electrode active material portion 743 and the negative electrode active material portion 753 of the electrode body 700, a larger area of ​​the active material layer can be secured compared to forming a through-hole in an area of ​​the electrode body 700 where the active material layer is not formed. This suppresses the reduction in the capacity of the energy storage element 10 caused by forming the through-hole 730.

[0069] In the electrode body 700, by forming a plurality of through holes 730 aligned along the winding axis L, the electrolyte or gas can easily pass between the inside and outside of the electrode body 700 through the plurality of through holes 730 along the winding axis L. This makes it easier to impregnate the electrode body 700 with electrolyte or to degas from the electrode body 700 (including the discharge of gas generated during thermal runaway, etc.; the same applies hereinafter). In particular, since the electrode body 700 has a long shape along the winding axis L, it may be difficult to impregnate the electrode body 700 with electrolyte or to degas from the electrode body 700. For this reason, forming a plurality of through holes 730 aligned along the winding axis L in the electrode body 700 is highly effective.

[0070] In an electrode body 700 having a curved portion 711 and a flat portion 712, forming a through hole 730 in the curved portion 711 in the Z-axis positive direction is more effective in facilitating the impregnation of electrolyte into the electrode body 700 or the degassing of gas from within the electrode body 700. However, if the through hole 730 is formed at a position where the curve of the curved portion 711 is sharp, there is a risk that the active material layer around the through hole 730 may peel off or be damaged during the winding of the electrode plate. For this reason, the through hole 730 is formed near the boundary between the curved portion 711 and the flat portion 712 (at least one of the positions in the curved portion 711 close to the flat portion 712, and the position in the flat portion 712 close to the curved portion 711). This makes it possible to facilitate the impregnation of electrolyte into the electrode body 700 or the degassing of gas from within the electrode body 700 through the through hole 730, while suppressing damage to the active material layer around the through hole 730.

[0071] In the electrode body 700, the positive electrode through-hole 743a of the positive electrode active material portion 743 and the negative electrode through-hole 753a of the negative electrode active material portion 753 are positioned so that at least a portion of them overlap. This makes it easier for electrolyte or gas to pass between the inside and outside of the electrode body 700 through the positive electrode through-hole 743a and the negative electrode through-hole 753a, thereby facilitating the impregnation of electrolyte into the electrode body 700 or the degassing of gas from within the electrode body 700.

[0072] By positioning the negative electrode through-hole 753a inside the positive electrode through-hole 743a, the positive electrode active material portion 743 can be covered by the negative electrode active material portion 753, thereby suppressing problems such as electrodeposition occurring on the negative electrode plate 750. A similar effect can be expected even if the negative electrode through-hole 753a is not inside the positive electrode through-hole 743a, but rather the edges of both through-holes coincide and do not protrude.

[0073] In the electrode body 700, by forming a through hole 730 in the outermost active material portion (for example, the negative electrode active material portion 753), the inside and outside of the electrode body 700 are connected, making it easier for electrolyte or gas to pass between the inside and outside of the electrode body 700 through the through hole 730. This makes it easier to impregnate the electrode body 700 with electrolyte or to degas the inside of the electrode body 700 with gas.

[0074] In the electrode body 700, separators 761 and 762 are formed with separator through-holes 761a and 762a, respectively, which are positioned so that at least a portion of them overlap with the positive electrode through-hole 743a and the negative electrode through-hole 753a. By forming separator through-holes 761a and 762a in separators 761 and 762 in this way, electrolyte or gas can easily pass between the inside and outside of the electrode body 700 through the separator through-holes 761a and 762a. This makes it easier to impregnate the electrode body 700 with electrolyte or to degas the electrode body 700 from within.

[0075] In the electrode body 700, multiple positive electrode through holes 743a and multiple negative electrode through holes 753a are continuously formed in multiple positive electrode active material portions 743 and multiple negative electrode active material portions 753. This makes it easier for electrolyte or gas to pass between the inside and outside of the electrode body 700 through the multiple positive electrode through holes 743a and multiple negative electrode through holes 753a, thereby facilitating the impregnation of electrolyte into the electrode body 700 or the degassing of gas from within the electrode body 700.

[0076] By forming a through-hole 730 in the part of the electrode body 700 that is on the side of the liquid injection section 130, the through-hole 730 is positioned close to the liquid injection section 130. This makes it easier for the electrolyte or gas to pass between the inside and outside of the electrode body 700 through the through-hole 730, thus facilitating the impregnation of the electrode body 700 with electrolyte or the degassing of gas from inside the electrode body 700.

[0077] [4. Explanation of variations] (Variation 1) Next, a modification 1 of the above embodiment will be described. Figure 6 is a front view and a cross-sectional view showing the configuration of the through hole 730 of the electrode body according to modification 1 of this embodiment. Specifically, Figure 6 corresponds to Figure 5.

[0078] As shown in Figure 6, in this modified example, instead of the positive electrode through-hole 743a in the above embodiment, a positive electrode through-hole 743b is formed in the positive electrode active material portion 743 as a through-hole 730. The other configurations of this modified example are the same as in the above embodiment, so a detailed explanation is omitted.

[0079] The positive electrode through-hole 743b has a shape in which the direction intersecting the winding axis L is longer than the direction along the winding axis L. Specifically, the positive electrode through-hole 743b has a shape in which the winding direction (Z-axis direction) is longer than the winding axis direction (X-axis direction). In this embodiment, the positive electrode through-hole 743b is an oval-shaped through-hole that is longer in the Z-axis direction than in the X-axis direction.

[0080] The positive electrode through-hole 743b may be an elliptical, rectangular, or other polygonal through-hole, with the Z-axis direction being longer than the X-axis direction. It is preferable that the positive electrode through-hole 743b replaces all of the positive electrode through-holes 743a in the above embodiment, but any of the positive electrode through-holes 743a may remain unchanged from the positive electrode through-hole 743b.

[0081] As described above, the energy storage element according to this modified example can achieve the same effects as the above embodiment. In particular, when the positive electrode plate 740 and the negative electrode plate 750 are wound in the electrode body, a misalignment may occur in a direction intersecting the direction along the winding axis L (Z-axis direction). For this reason, as in this modified example, by forming the positive electrode through-hole 743b in a shape that is elongated in the direction intersecting the direction along the winding axis L (Z-axis direction), the misalignment between the positive electrode through-hole 743b and the negative electrode through-hole 753a caused by winding the positive electrode plate 740 and the negative electrode plate 750 is suppressed. As a result, the misalignment between the positive electrode through-hole 743b and the negative electrode through-hole 753a, which would make it difficult for electrolyte or gas to pass between the inside and outside of the electrode body, can be suppressed, and thus the impregnation of electrolyte into the electrode body or the degassing of gas from the electrode body can be facilitated. The configuration is not limited to having only the positive electrode through-hole 743b have a shape where the direction intersecting the winding axis L is longer than the direction along the winding axis L. The shapes of the negative electrode through-hole 753a and the separator through-holes 761a and 762a may also be molded to correspond to the shape of the positive electrode through-hole 743b.

[0082] (Modification 2) Next, a second modification of the above embodiment will be described. Figure 7 is a perspective view showing the configuration of the electrode body 701 according to the second modification of this embodiment. Specifically, Figure 7 is a diagram corresponding to the electrode body 700 shown in Figure 4.

[0083] As shown in Figure 7, the electrode body 701 in this modified example has, in addition to the configuration of the electrode body 700 in the above embodiment, a cylindrical member 770 disposed within the through hole 730. The other configurations of this modified example are the same as in the above embodiment, so a detailed explanation is omitted.

[0084] The cylindrical member 770 is a cylindrical porous pipe inserted into the multiple through holes 730 (multiple positive electrode through holes 743a, multiple negative electrode through holes 753a, and multiple separator through holes 761a and 762a). The cylindrical member 770 is inserted into the multiple through holes 730 and positioned from the outermost layer (outermost circumference) active material portion to the innermost layer (innermost circumference) active material portion of the electrode body 700. The cylindrical member 770 is formed from any resin foam (PP foam, PE foam, etc.) that can be used for the upper gasket 400 (lower gasket 500), or from any porous material that can be used for the separators 761 and 762.

[0085] The cylindrical member 770 is not particularly limited in shape as long as it is cylindrical, and may be an elongated cylinder, an elliptical cylinder, a rectangular cylinder, or other polygonal cylinder shapes. It is preferable that the cylindrical member 770 be placed in all of the through holes 730, but it is also possible that it is not placed in any of the through holes 730.

[0086] As described above, the energy storage element according to this modified example can achieve the same effects as the embodiment described above. In particular, in this modified example, since the cylindrical member 770 is placed inside the through hole 730 of the electrode body 701, it is possible to suppress contamination (metal powder, etc.) from entering the inside of the electrode body 701 through the through hole 730 when injecting the electrolyte, etc.

[0087] (Variation 3) Next, a third modification of the above embodiment will be described. Figure 8 is a perspective view showing the configuration of the electrode body 702 according to the third modification of this embodiment. Specifically, Figure 8 corresponds to Figure 3.

[0088] As shown in Figure 8, in this modified example, the electrode body 702 has positive electrode markers 744 and negative electrode markers 754 formed on the positive electrode substrate 741 and negative electrode substrate 751 of the electrode body 700 in the above embodiment. The other configurations of this modified example are the same as in the above embodiment, so a detailed explanation is omitted.

[0089] The positive electrode marker 744 is a circular through-hole formed at the X-axis positive end of the positive electrode substrate 741 and is arranged in the X-axis positive direction of the multiple through-holes 730 (positive electrode through-holes 743a). The negative electrode marker 754 is a circular through-hole formed at the X-axis negative end of the negative electrode substrate 751 and is arranged in the X-axis negative direction of the multiple through-holes 730 (negative electrode through-holes 753a).

[0090] The positive electrode marker 744 and the negative electrode marker 754 may be through holes of a shape other than circular, or they may be notches, recesses, or protrusions (tabs) instead of through holes, or they may be colored portions. In other words, the positive electrode marker 744 and the negative electrode marker 754 may be markers (marks) that can be recognized by visual inspection or image analysis.

[0091] As described above, the energy storage element according to this modified example can achieve the same effects as the above embodiment. In particular, in this modified example, since the positive electrode marker 744 and the negative electrode marker 754 are positioned adjacent to the through-hole 730 (positive electrode through-hole 743a and negative electrode through-hole 753a), the misalignment of the through-hole 730 can be confirmed using the positive electrode marker 744 and the negative electrode marker 754. This allows the electrode plates in the electrode body 702 to be wound while correcting the misalignment of the through-hole 730. The positions of the positive electrode marker 744 and the negative electrode marker 754 are not particularly limited, as long as they can confirm the misalignment of the through-hole 730.

[0092] (Other variations) Although embodiments of the present invention (including modifications thereof; the same applies hereinafter) of energy storage elements have been described above, 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.

[0093] In the above embodiment, the through-hole 730 of the electrode body is positioned close to the curved portion 711 in the Z-axis positive direction on the flat portion 712 in the Y-axis negative direction. However, the position of the through-hole 730 in the electrode body is not particularly limited. The through-hole 730 may be positioned close to the curved portion 711 in the Z-axis positive direction on the flat portion 712 in the Y-axis positive direction, or it may be positioned close to the curved portion 711 in the Z-axis positive direction on both sides of the flat portion 712 in the Y-axis direction. The through-hole 730 may be positioned close to the flat portion 712 on the curved portion 711 in the Z-axis positive direction. The through-hole 730 may be positioned far from the flat portion 712 on the curved portion 711, or far from the curved portion 711 on the flat portion 712.

[0094] In the above embodiment, the through-holes 730 of the electrode body are arranged in a line along the winding axis L (X-axis direction), but the direction of arrangement of the through-holes 730 is not particularly limited. Multiple through-holes 730 may be arranged in a line along the Z-axis direction, or multiple through-holes 730 may be arranged randomly. The number of through-holes 730 is also not particularly limited, and the electrode body may have only one through-hole 730. In this case, it is preferable that the through-hole 730 is located in the center of the electrode body in the direction along the winding axis L (X-axis direction).

[0095] In the above embodiment, through holes 730 (positive electrode through holes and negative electrode through holes 753a) are formed in all of the stacked positive electrode active material portions 743 and negative electrode active material portions 753. However, through holes 730 do not have to be formed in any of the positive electrode active material portions 743 or any of the negative electrode active material portions 753. Similarly, with respect to the separators 761 and 762, there may be locations between the outermost separators 761 and 762 in the electrode body and the innermost separators 761 and 762 where through holes 730 (separator through holes 761a and 762a) are not formed. The through-holes 730 of the electrode body may be formed in a row or continuously from one outer surface to the other outer surface at positions that overlap when viewed from the Y-axis direction, or they may be formed in a row or continuously from one outer surface to the innermost layer (innermost circumference) of the electrode body, with no through-holes 730 on the other outer surface, or they may be positioned offset from one outer surface when viewed from the Y-axis direction.

[0096] In the above embodiment, through holes 730 (positive electrode through hole and negative electrode through hole 753a) are formed in both the positive electrode active material portion 743 and the negative electrode active material portion 753. However, through holes 730 may be formed in only one of the positive electrode active material portion 743 and the negative electrode active material portion 753. Similarly, for separators 761 and 762, through holes 730 (separator through holes 761a, 762a) may be formed in only one of the separators 761 and 762, or through holes 730 may not be formed in both separators 761 and 762.

[0097] In the above embodiment, the negative electrode through-hole 753a has a smaller shape than the positive electrode through-hole when viewed from the Y-axis direction and is positioned inside the positive electrode through-hole. However, the negative electrode through-hole 753a may not be positioned inside the positive electrode through-hole, but may be positioned at a slightly offset position, or at a position that does not overlap with the positive electrode through-hole, and the shape, size relationship, and position of the positive electrode through-hole and negative electrode through-hole 753a are not particularly limited. However, even in this case, it is preferable that there is no portion of the positive electrode active material layer 742 (active positive electrode active material layer 742) that does not face the negative electrode active material layer 752. In other words, it is preferable that the entire positive electrode active material layer 742 (active positive electrode active material layer 742) faces the negative electrode active material layer 752. The positive electrode active material layer 742 around the positive electrode through-hole may be coated with resin or impregnated with resin. This deactivates the positive electrode active material layer 742 around the positive electrode through-hole, allowing only the active positive electrode active material layer 742 to face the negative electrode active material layer 752, thereby suppressing lithium electrodeposition onto the negative electrode plate 750. Any resin material that does not react with the positive electrode active material layer 742 is acceptable as the resin, but polyolefin resins such as PE and PP are suitable because they do not react with the positive electrode active material layer 742, can be dissolved by heating the resin material, and can be easily applied or impregnated.

[0098] In the above embodiment, the separator through-holes 761a and 762a are positioned inside the positive electrode through-hole and negative electrode through-hole 753a when viewed from the Y-axis direction. However, the separator through-holes 761a and 762a may be positioned slightly offset from the positive electrode through-hole and negative electrode through-hole 753a, or they may be positioned so as not to overlap with the positive electrode through-hole and negative electrode through-hole 753a. In addition, one of the positive electrode through-hole or the negative electrode through-hole 753a may be positioned inside the other, or both the positive electrode through-hole and the negative electrode through-hole 753a may be positioned inside. In other words, the shape, relative size, and position of the separator through-holes 761a and 762a and the positive electrode through-hole and negative electrode through-hole 753a are not particularly limited.

[0099] In the above embodiment, the liquid injection section 130 is formed on the lid 120 of the container 100. However, the liquid injection section 130 may also be formed on the container body 110 of the container 100, and the position of the liquid injection section 130 is not particularly limited. If the liquid injection section 130 is formed on the wall portion (short side wall portion) in the X-axis direction of the container 100, the through hole 730 of the electrode body may be formed at the end of the electrode body in the X-axis direction.

[0100] In the above embodiment, the through-hole 730 of the electrode body is formed in the part of the electrode body on the side of the liquid injection part 130. However, the through-hole 730 may be located in any position, and may be formed in the part of the electrode body opposite to the liquid injection part 130. In other words, the through-hole 730 may be formed in the part of the electrode body on the bottom side of the container 100. Figure 9 is a perspective view showing the configuration of the electrode body 703 according to Modification 4 of this embodiment. Specifically, Figure 9 is a diagram corresponding to the electrode body 700 shown in Figure 4. As shown in Figure 9, in this modification, the through-hole 730 of the electrode body 703 in the above embodiment is formed in the part of the electrode body 703 on the bottom side of the container 100 (in the negative Z-axis direction). Preferably, the through-hole 730 is formed in at least one of the positions on the bottom side of the container 100, where the curved part 711 is close to the flat part 712, and where the flat part 712 is close to the curved part 711, but it may be formed in any other position on the bottom side of the container 100. The other components of this modified example are the same as those of the above embodiment, so a detailed explanation will be omitted. As described above, the energy storage element according to this modified example can achieve the same effects as the above embodiment. In particular, in this modified example, by forming a through hole 730 in the part of the electrode body 703 that is on the bottom side of the container 100, the electrolyte can be retained in the central part of the electrode body 703 even when the amount of electrolyte in the container 100 is small (for example, at the end of its lifespan).

[0101] In the above embodiment, the pair of electrode terminals 300 are both positioned to protrude from the container 100 in the Z-axis positive direction. However, the direction in which the pair of electrode terminals 300 protrude is not particularly limited. The pair of electrode terminals 300 may protrude from the container 100 in either direction along the X axis, or they may protrude in both directions along the X axis.

[0102] In the above embodiment, the electrode body is a so-called vertically wound electrode body in which the winding axis L is parallel to the cover 120. However, the electrode body may also be a so-called horizontally wound electrode body in which the winding axis L is perpendicular to the cover 120. In the above embodiment, the electrode body is a long cylindrical shape (flattened shape) having a curved portion 711 and a flat portion 712, but it may also be a cylindrical shape or an elliptical cylindrical shape, and the shape is not particularly limited as long as it is a wound electrode body. In the electrode body, the end portion 720 may be a tab portion (a portion in which multiple tabs of the electrode plate are stacked) protruding from a part of the electrode body main portion 710. The electrode body does not have to be elongated in the X-axis direction.

[0103] The present invention also includes forms constructed by arbitrarily combining the components included in the above embodiments and their modified examples.

[0104] This invention can be realized not only as such an energy storage element, but also as an electrode body. [Industrial applicability]

[0105] This invention can be applied to energy storage elements such as lithium-ion secondary batteries. [Explanation of Symbols]

[0106] 10 Energy storage elements 100 containers 110 Container body 120 Lid 130 Injection section 300 electrode terminal 600 Current collector 700, 701, 702 electrode body 710 Electrode body part 711 Curved section 712 Flat area 720 End 730 Through hole 740 Positive Plate 741 Positive electrode substrate 742 Cathode active material layer 743 Cathode active material section 743a, 743b Positive electrode through hole 744 Positive electrode marker 750 Negative plate 751 Negative electrode substrate 752 Negative electrode active material layer 753 Negative electrode active material section 753a Negative electrode through hole 754 Negative electrode marker 761, 762 Separators 761a, 762a Separator through-holes 770 Cylindrical member

Claims

1. An energy storage element comprising an electrode body, The electrode body is formed by winding a positive electrode plate and a negative electrode plate around a winding axis, The positive electrode plate has a positive electrode active material portion in which a positive electrode active material layer is formed on a positive electrode substrate. The negative electrode plate has a negative electrode active material portion in which a negative electrode active material layer is formed on a negative electrode substrate, A through hole is formed in at least one of the positive electrode active material portion and the negative electrode active material portion. The electrode body has a curved portion and a flat portion, formed by winding the positive electrode plate and the negative electrode plate around the winding shaft. The through-hole is formed at least one of the following locations: a position in the curved portion close to the flat portion, and a position in the flat portion close to the curved portion. Energy storage element.

2. Furthermore, the container for housing the electrode body is provided. The through-hole is formed in the electrode body on the side opposite to the bottom surface of the container. The energy storage element according to claim 1.

3. The positive electrode active material portion has a positive electrode through-hole formed therein. The negative electrode active material portion has a negative electrode through-hole formed therein. The positive electrode through-hole and the negative electrode through-hole are positioned so that at least a portion of them overlap when viewed from the direction in which they are aligned. The energy storage element according to claim 1 or 2.

4. An energy storage element comprising an electrode body, The electrode body is formed by winding a positive electrode plate and a negative electrode plate around a winding axis, The positive electrode plate has a positive electrode active material portion in which a positive electrode active material layer is formed on a positive electrode substrate. The negative electrode plate has a negative electrode active material portion in which a negative electrode active material layer is formed on a negative electrode substrate, A through hole is formed in at least one of the positive electrode active material portion and the negative electrode active material portion. The positive electrode active material portion has a positive electrode through-hole formed therein. The negative electrode active material portion has a negative electrode through-hole formed therein. The positive electrode through-hole and the negative electrode through-hole are positioned so that at least a portion of them overlap when viewed from the direction in which they are aligned. At least one of the positive electrode through-hole and the negative electrode through-hole has a shape in which the direction intersecting the direction along the winding axis is longer than the direction along the winding axis. Energy storage element.

5. The positive electrode plate and the negative electrode plate are wound together so that a plurality of the positive electrode active material portions and a plurality of the negative electrode active material portions are stacked in the stacking direction. The plurality of positive electrode active material portions and the plurality of negative electrode active material portions are formed with a plurality of positive electrode through holes and a plurality of negative electrode through holes arranged continuously in the stacking direction. The energy storage element according to claim 3 or 4.

6. The aforementioned through holes are formed in a plurality of rows in the direction along the winding axis. The energy storage element according to any one of claims 1 to 5.

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