Electric storage device

Abstract

An electricity storage element is provided with an electrode body, the electrode body is provided with a pole plate having a current collector foil and an active material layer, the pole plate is wound around a winding axis extending in a first direction, and the electrode body is provided with an active material forming part in which the active material layer is formed in a second direction orthogonal to the first direction of the current collector foil. The active material forming part constitutes a plurality of layers in the second direction, each of two or more contiguous layers among the plurality of layers is provided with one or more electrode holes, the electrode holes are through holes penetrating both the current collector foil and the active material layer, the opening area of the electrode holes is 0.02 mm2 or less, and when viewed from the second direction, the electrode body extends across each of the two or more layers. An electrode hole group in which the electrode holes of each layer are dense in a given region is formed.

Description

Energy storage components Technical Field

[0001] This invention relates to energy storage components. Background Technology

[0002] Patent Document 1 discloses a wound-type energy storage device comprising a wound electrode body formed by stacking and winding a positive electrode plate and a negative electrode plate with a separator in between. The positive electrode plate has a plurality of positive electrode through holes arranged along its long side, and the negative electrode plate has a plurality of negative electrode through holes arranged along its long side. The positive electrode through holes and the negative electrode through holes overlap each other with a separator in between, thereby forming a ventilation path from the inside of the electrode body to the outer periphery.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2006-210031 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In energy storage devices with an electrode body having wound plates, it is sometimes difficult for the electrolyte to penetrate into the electrode body during electrolyte injection. Therefore, forming through holes in the electrode body is considered. In the wound-type energy storage device disclosed in Patent Document 1, since a venting path is formed in the wound-type electrode body, it is considered to allow the electrolyte to penetrate into the wound-type electrode body through this venting path. However, in this wound-type energy storage device, there are concerns about the generation of burrs or contaminants (such as metal powder) caused by the formation of the venting path, or a decrease in capacity. It is desirable to achieve a structure that allows the electrolyte to easily penetrate into the electrode body while suppressing the generation of such adverse conditions.

[0008] The present invention was made by the inventors of this application with a new focus on the above-mentioned problems. Its purpose is to provide an energy storage element that can easily allow the electrolyte to penetrate into the electrode body while suppressing the occurrence of adverse conditions.

[0009] Methods for solving problems

[0010] One aspect of the present invention relates to an energy storage element comprising an electrode body, the electrode body comprising an electrode plate, the electrode plate comprising a current-collecting foil and an active material layer, the electrode plate being wound around a winding shaft extending in a first direction, and having an active material forming portion on the current-collecting foil having the active material layer formed in a second direction orthogonal to the first direction, the active material forming portion comprising multiple layers in the second direction, each of two or more consecutive layers comprising one or more electrode holes, the electrode holes being through holes penetrating both the current-collecting foil and the active material layer, the opening area of ​​the electrode holes being 0.02 mm. 2 Hereinafter, in the electrode body, viewed from the second direction, each of the two or more layers forms a dense group of electrode holes in a given area.

[0011] Invention Effects

[0012] The energy storage element according to the present invention can facilitate the penetration of electrolyte into the electrode body while suppressing the occurrence of adverse conditions. Attached Figure Description

[0013] Figure 1 is a perspective view showing the appearance of the energy storage element involved in the embodiment.

[0014] Figure 2 is an exploded perspective view showing the constituent elements of the energy storage element involved in the embodiment.

[0015] Figure 3 is a perspective view and a cross-sectional view showing the structure of the electrode body involved in the embodiment.

[0016] Figure 4 is a perspective view showing the structure with a portion of the electrode plate in the electrode body according to the embodiment unwound from its wound state.

[0017] Figure 5 is a front view showing the structure of the electrode holes and electrode hole group of the electrode body involved in the embodiment.

[0018] Figure 6 is a front view and a cross-sectional view showing an enlarged view of the structure of the electrode holes and a portion of the electrode hole group of the electrode body involved in the embodiment.

[0019] Figure 7 is a front view showing the structure of the electrode holes and electrode hole group of the electrode body involved in the modified example 1 of the embodiment.

[0020] Figure 8 is a front view showing the structure of the electrode holes and electrode hole group of the electrode body involved in the modified example 2 of the embodiment.

[0021] Figure 9 is a front view showing the structure of the electrode holes and electrode hole group of the electrode body involved in the modified example 3 of the embodiment.

[0022] Figure 10 is a front view showing the structure of the electrode holes and electrode hole group of the electrode body according to the modified example 4 of the embodiment.

[0023] Figure 11 is a perspective view showing the structure of the electrode holes formed in the electrode hole group of the electrode body according to the modified example 5 of the embodiment.

[0024] Figure 12 is a top view showing an example of an energy storage device according to a variation of embodiment 6. Detailed Implementation

[0025] (1) An energy storage element according to one aspect of the present invention includes an electrode body, the electrode body includes an electrode plate, the electrode plate includes a current-collecting foil and an active material layer, the electrode plate is wound around a winding shaft extending in a first direction, and includes an active material forming portion in which the active material layer is formed in a second direction orthogonal to the first direction of the current-collecting foil, the active material forming portion having multiple layers in the second direction, each of two or more consecutive layers including one or more electrode holes, the electrode holes being through holes penetrating both the current-collecting foil and the active material layer, and the opening area of ​​the electrode holes being 0.02 mm. 2 Hereinafter, in the electrode body, viewed from the second direction, each of the two or more layers forms a dense group of electrode holes in a given area.

[0026] Accordingly, in the energy storage element, each of the two or more consecutive layers formed by the active material forming portion of the wound electrode plate of the electrode body has an opening area of ​​0.02 mm². 2 The electrode pores below, viewed from the second direction, form a dense group of electrode pores in each layer within a given area. Electrode bodies with wound plates are difficult for electrolyte to penetrate, but this dense group of electrode pores in each layer of the electrode body, where active material forming portions are formed, allows electrolyte to easily penetrate the electrode body through each pore. Since the electrode pore has an opening area of ​​0.02 mm²... 2 The tiny electrode pores, as shown below, can suppress the risk of micro-short circuits caused by burrs or contaminants, or the reduction in capacity (energy density) caused by a decrease in the effective electrode area. This allows the electrolyte to easily penetrate the electrode body while suppressing these adverse conditions.

[0027] (2) In the energy storage element described in (1) above, the maximum width of the given area is less than 50 mm when viewed from the second direction.

[0028] Accordingly, by making the maximum width of a given area where the electrode holes of each layer in the electrode hole group are densely arranged less than 50 mm, the permeability of the electrolyte to each layer through the electrode holes can be improved because the electrode holes of each layer are close together.

[0029] (3) In the energy storage element described in (1) or (2) above, each of the two or more layers in the electrode hole group may have a plurality of electrode holes.

[0030] Accordingly, by setting multiple electrode holes in each layer of the electrode hole group, electrolyte can be efficiently permeated into each layer through multiple electrode holes.

[0031] (4) In any of the above (1) to (3) energy storage elements, the electrode plate may have a positive electrode plate and a negative electrode plate, and the electrode holes are provided in all layers of the plurality of layers of the active material forming portion of the positive electrode plate and the plurality of layers of the active material forming portion of the negative electrode plate.

[0032] Accordingly, by providing electrode holes in all layers of the active material forming portion of the positive and negative electrode plates in the electrode hole group, electrolyte can be permeated into all layers of the positive and negative electrode plates, thus enabling electrolyte to permeate into the electrode body more effectively.

[0033] (5) In any of the above (1) to (4) energy storage elements, the total opening area of ​​all the electrode holes provided in the active material forming part is 3% or less relative to the area of ​​the active material forming part.

[0034] Accordingly, by reducing the ratio of the total opening area of ​​all electrode holes to the area of ​​the active material forming part to less than 3%, it is possible to suppress the reduction of the effective electrode area caused by the provision of electrode holes in the active material forming part.

[0035] (6) In any of the above (1) to (5) energy storage elements, two or more of the electrode hole groups are formed in the electrode body, and when viewed from the second direction, the distance between the electrode holes in the electrode hole group is less than the distance between two adjacent electrode hole groups.

[0036] Therefore, because the distance between the electrode pores within the electrode pore group is relatively small, the electrolyte can effectively penetrate into the electrode body. Because the distance between two adjacent electrode pore groups is relatively large, damage to the electrode plates, such as plate breakage, can be suppressed between these two electrode pore groups.

[0037] (7) In the energy storage element described in (6) above, the distance between the two electrode hole groups in the first direction can be set as the first distance, and the distance between the two electrode hole groups in a third direction orthogonal to the first direction and the second direction can be set as the second distance, wherein the first distance is greater than the second distance.

[0038] Accordingly, the first distance between the two groups of electrode holes in the first direction is greater than the second distance between the two groups of electrode holes in the third direction. By distributing the electrode holes at a fixed distance (the first distance in the first direction and the second distance in the third direction), the reduction in effective electrode area caused by the placement of the electrode holes can be suppressed. By increasing the distance between the groups of electrode holes in the first direction (the first distance), damage to the electrode plates, such as electrode breakage, can be further suppressed.

[0039] (8) In the energy storage element described in (7) above, the first distance may be greater than 10 times the second distance.

[0040] Accordingly, by making the first distance greater than 10 times the second distance, since the electrode holes are distributed at larger intervals in the first direction, the reduction in effective electrode area caused by the provision of electrode holes can be more effectively suppressed. By making the first distance greater than 10 times the second distance, since the distance between the electrode holes in the first direction is further increased, damage to the electrode plates, such as electrode plate breakage, between the electrode holes can be further suppressed.

[0041] Hereinafter, the energy storage element according to embodiments (including variations thereof) of the present invention will be described with reference to the accompanying drawings. The embodiments described below are general or specific examples. The numerical values, shapes, materials, constituent elements, arrangement positions of constituent elements, connection methods, manufacturing processes, and order of manufacturing processes shown in the following embodiments are examples and are not intended to limit the present invention. Dimensions are not strictly illustrated in the figures. The same or identical constituent elements are labeled with the same symbols in the figures.

[0042] In the following description and accompanying drawings, the X-axis direction is defined as the arrangement direction of a pair of terminals (positive and negative, hereinafter the same) of the energy storage element, the arrangement direction of a pair of current collectors, the winding axis direction of the electrode body, the extension direction (width being the longest) of the electrode body or container, or the opposing direction of a pair of short sides in the container. The Y-axis direction is defined as the thickness direction of the container (the direction where the width of the container is the shortest), the opposing direction of a pair of long sides in the container, or the opposing direction of a pair of flat portions of the electrode body. The Z-axis direction is defined as the arrangement direction of the container body and the lid, the opposing direction of a pair of curved portions of the electrode body, or the up-down direction. These X-axis, Y-axis, and Z-axis directions are intersecting (orthogonal in this embodiment). Depending on the usage, the case where the Z-axis direction is not the up-down direction is also considered, but for ease of explanation, the Z-axis direction will be described as the up-down direction below.

[0043] In the following description, the positive X-axis direction refers to the direction of the arrow on the X-axis, and the negative X-axis direction refers to the direction opposite to the positive X-axis direction. When referred to simply as the X-axis direction, it means either the positive or negative X-axis direction. The same applies to the Y-axis and Z-axis directions. Hereinafter, the X-axis direction will also be referred to as the first direction, the Y-axis direction as the second direction, and the Z-axis direction as the third direction. The terms parallel and orthogonal, indicating relative directions or orientations, strictly include cases where the direction or orientation is not the stated one. The term "two directions parallel" not only means that the two directions are completely parallel, but also that they are substantially parallel, i.e., including, for example, a difference of approximately a few percent. In the following description, when expressed as "insulating," it means "electrically insulating." The insulating material preferably has a volume resistivity of 1 × 10⁻⁶. 10 Materials with an Ωm or greater are formed.

[0044] (Implementation Method)

[0045] [1. Overall description of the energy storage element 10]

[0046] First, the overall structure of the energy storage element 10 in this embodiment will be explained using Figures 1 and 2. Figure 1 is a perspective view showing the appearance of the energy storage element 10 according to this embodiment. Figure 2 is an exploded perspective view showing the constituent elements of the energy storage element 10 according to this embodiment.

[0047] The energy storage element 10 is a secondary battery (single cell) capable of charging and discharging electricity, 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 driving or starting engines of moving vehicles such as automobiles, motorized two-wheelers, jet skis, ships, snowmobiles, agricultural machinery, construction machinery, automated guided vehicles (AGVs), 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, light oil, liquefied natural gas, etc.) vehicles. Examples of railway vehicles for electric railways include trams, monorail trains, linear electric vehicles, and hybrid trams equipped with both an internal combustion engine and an electric motor. The energy storage element 10 can also be used as a battery for stationary installations in homes or businesses.

[0048] The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery; it can also be a secondary battery other than a non-aqueous electrolyte secondary battery, or it can be a capacitor. The energy storage element 10 may also not be a secondary battery; it can be a primary battery. The energy storage element 10 can also be a pouch-shaped energy storage element. In this embodiment, the figure shows an energy storage element 10 with a flat rectangular (square) shape in the Y-axis direction; however, the shape of the energy storage element 10 is not limited to a rectangular shape; it can also be a polygonal prism shape other than a rectangular prism, a long cylindrical shape, an elliptical cylindrical shape, or a cylindrical shape, etc.

[0049] As shown in Figure 1, the energy storage element 10 includes: a container 100, a pair of terminals (positive and negative) 300, and a pair of upper pads 400 (positive and negative). As shown in Figure 2, the energy storage element 10 also includes a pair of lower pads 500 (positive and negative), a pair of current collectors 600 (positive and negative), and an electrode body 700, which are housed inside the container 100. In addition to the above-mentioned components, spacers or insulating films surrounding the electrode body 700 may also be provided on the side or below the electrode body 700.

[0050] Inside container 100, an electrolyte (non-aqueous electrolyte) is sealed, but the illustration is omitted. 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; a wide variety of electrolytes can be selected. The electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. As the non-aqueous solvent, it can be appropriately selected from known non-aqueous solvents. Examples of non-aqueous solvents include cyclic carbonates such as ethylene carbonate (EC) or propylene carbonate (PC), chain carbonates such as ethyl methyl carbonate (EMC), carboxylic acid esters, phosphate esters, sulfonates, ethers, amides, nitriles, etc. Non-aqueous solvents in which some of the hydrogen atoms are replaced by halogens can also be used. As the electrolyte salt, it can be appropriately selected from known electrolyte salts. Examples of electrolyte salts include inorganic lithium salts such as LiPF6, sodium salts, potassium salts, magnesium salts, onium salts, etc. Among these, lithium salts are preferred. In addition to the non-aqueous solvent and electrolyte salt, the electrolyte may also include additives such as biphenyl.

[0051] Container 100 is a rectangular (square or box-shaped) shell comprising a container body 110 having an opening in the positive Z-axis direction and a lid 120 sealing the opening of the container body 110. The lid 120 is a flat, rectangular member constituting the lid of container 100, disposed in the positive Z-axis direction of container body 110. The lid 120 is a wall extending along the winding axis direction of electrode body 700. The winding axis direction of electrode body 700 refers to the direction in which the winding axis L of electrode body 700 extends, as described later; in this embodiment, it is the X-axis direction.

[0052] The container body 110 is a rectangular cylindrical component constituting the main body of the container 100 and having a bottom. The container body 110 has a pair of long sidewalls 111 on both sides of the Y-axis direction, a pair of short sidewalls 112 on both sides of the X-axis direction, and a bottom wall 113 on the negative Z-axis direction. The long sidewalls 111 are flat and rectangular wall portions extending along the X-axis direction (the winding axis direction of the electrode body 700), including the long side surface of the container 100. The long sidewalls 111 are adjacent to the short sidewalls 112, the bottom wall 113, and the cover 120, and have a larger area than the short sidewalls 112. The short sidewalls 112 are flat and rectangular wall portions extending along the Z-axis direction, including the short side surface of the container 100. The short sidewall portion 112 is adjacent to the long sidewall portion 111, the bottom wall portion 113, and the cover 120, and its area is smaller than that of the long sidewall portion 111. The bottom wall portion 113 is a flat and rectangular wall portion extending along the X-axis direction (the winding axis direction of the electrode body 700), including the bottom surface of the container 100. The bottom wall portion 113 is arranged adjacent to the long sidewall portion 111 and the short sidewall portion 112.

[0053] After the electrode body 700 and the like are housed inside the container body 110, the container body 110 and the cover 120 are joined by welding or the like, thereby sealing the interior. The material of the container 100 (container body 110 and cover 120) is not particularly limited; it can be made of weldable metals such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet, or resin. The container body 110 and cover 120 can be made of the same material or different materials. If the energy storage element 10 is a pouch-type energy storage element, the container 100 can also be a laminated film consisting of multiple layers including a metal layer and a resin layer.

[0054] A liquid injection section 130 and a gas discharge valve 140 are formed in the container 100. In this embodiment, the liquid injection section 130 and the gas discharge valve 140 are formed on the cover 120. That is, the liquid injection section 130 and the gas discharge valve 140 are formed on a wall portion extending along the winding axis direction (X-axis direction) of the electrode body 700. The gas discharge valve 140 is a safety valve that releases pressure in case the pressure inside the container 100 rises excessively. In this embodiment, the gas discharge valve 140 is disposed at the center of the cover 120 in both the X-axis direction and the Y-axis direction, but it can be disposed at any position on the cover 120.

[0055] The electrolyte injection section 130 is used to inject electrolyte into the inside of the container 100 during the manufacture of the energy storage element 10. The electrolyte injection section 130 is used to evacuate the container 100, inject electrolyte into the container 100 to allow the electrolyte to permeate into the electrode body 700, or degas gas from the electrode body 700 during the manufacture of the energy storage element 10. In this embodiment, the electrolyte injection section 130 is located at the center of the cover 120 in the negative X-axis direction and Y-axis direction, but it can be located at any position on the cover 120.

[0056] The liquid injection section 130 includes a liquid injection port 131 and a liquid injection plug 132. The liquid injection port 131 is a through hole formed in the cover 120 for injecting electrolyte into the inside of the container 100, and in this embodiment, it is circular. The liquid injection plug 132 is a component that seals the liquid injection port 131. Specifically, the liquid injection plug 132 is a sealing component (cover component) that is joined to the cover 120 to seal the liquid injection port 131 after the container 100 is evacuated through the liquid injection port 131 and electrolyte is injected into the inside of the container 100 during the manufacture of the energy storage element 10. The material of the liquid injection plug 132 is not particularly limited, but any metal that can be used in the container 100 (cover 120) can be used. In particular, the liquid injection plug 132 is formed from a raw material that can be welded to the cover 120, such as the same material as the cover 120.

[0057] Terminal 300 is an electrode terminal (positive and negative terminals) electrically connected to electrode body 700 via current collector 600. Terminal 300 is a metallic component used to conduct electricity stored in electrode body 700 to the external space of energy storage element 10, and to introduce electricity into the internal space of energy storage element 10 in order to store electricity in electrode body 700. Terminal 300 is formed of conductive components such as aluminum, aluminum alloy, copper, or copper alloy. Terminal 300 is connected (joined) to current collector 600 by riveting or welding, and is mounted on cover 120. Terminal 300 is arranged to protrude from the outer surface (plane in the positive Z-axis direction) of cover 120 in the positive Z-axis direction. In this embodiment, terminal 300 is a welded terminal joined to an external conductive component such as a busbar by welding, but terminal 300 may also be a bolted terminal having a bolt portion with external threads protruding in the positive Z-axis direction and joined to the conductive component by bolting.

[0058] The current collector 600 is a conductive current collector component (positive current collector and negative current collector) disposed on both sides of the electrode body 700 in the X-axis direction, connected (joined) to the electrode body 700 and the terminal 300, and electrically connecting the electrode body 700 and the terminal 300. The current collector 600 is connected (joined) to the non-active material forming portion 720 of the electrode body 700 (described later) by welding or riveting, and is connected (joined) to the terminal 300 by riveting or welding, as described above, and is fixed to the cover body 120. The material of the current collector 600 is not particularly limited, but in this embodiment, the positive current collector 600 is made of aluminum or aluminum alloy, the same as the positive current collector foil 741 of the electrode body 700 (described later), and the negative current collector 600 is made of copper or copper alloy, the same as the negative current collector foil 751 of the electrode body 700 (described later).

[0059] The upper gasket 400 is a plate-shaped and rectangular gasket disposed between the cover 120 and the terminal 300 of the container 100, providing insulation and sealing between the cover 120 and the terminal 300. The lower gasket 500 is a plate-shaped and rectangular gasket disposed between the cover 120 and the current collector 600, providing insulation between the cover 120 and the current collector 600. The upper gasket 400 and the lower gasket 500 are formed from insulating components such as polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyetheretherketone (PEEK), tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polyamide (PA), ABS resin, or composite materials thereof.

[0060] The electrode body 700 is an energy storage element (power generation element) formed by stacking electrode plates and insulating members. In this embodiment, the electrode body 700 is formed by winding the electrode plates and insulating members. The electrode body 700 is a long strip extending along the X-axis direction and has an elongated cylindrical shape (viewed from the X-axis direction as an elongated oval shape). The electrode body 700 includes an electrode body main body portion 710 and active material non-forming portions 720 protruding from the electrode body main body portion 710 to both sides in the X-axis direction. As described above, the active material non-forming portions 720 are connected (joined) to the current collector 600. In the electrode body main body portion 710, an electrode hole group 730 having a plurality of electrode holes 731 described later is formed. The structure of such an electrode body 700 will be described in detail below.

[0061] [2. Explanation of the structure of electrode body 700]

[0062] Figure 3 is a perspective view and a cross-sectional view showing the structure of the electrode body 700 according to this embodiment. Figure 3(a) is a perspective view showing the appearance of the electrode body 700, and Figure 3(b) is a cross-sectional view showing the stacked state of the electrode plates by enlarging a portion of the cross-section of the electrode body 700. Figure 4 is a perspective view showing the structure of the electrode body 700 according to this embodiment with a portion of the wound state of the electrode plates unfolded.

[0063] [2.1 Description of the overall integrity of electrode body 700]

[0064] As shown in Figures 3 and 4, the electrode body 700 has two electrode plates as electrode plates, namely a positive electrode plate 740 and a negative electrode plate 750, and has two isolation members 760, namely isolation members 761 and 762, as isolation members.

[0065] The positive electrode plate 740 is an electrode plate (electrode plate) on the surface of a strip-shaped current collector foil (metal foil) containing metals such as aluminum or aluminum alloys, i.e., the positive current collector foil 741, on which a positive active material layer 742 is formed. The negative electrode plate 750 is an electrode plate (electrode plate) on the surface of a strip-shaped current collector foil (metal foil) containing metals such as copper or copper alloys, i.e., the negative current collector foil 751, on which a negative active material layer 752 is formed. As for the positive current collector foil 741 and the negative current collector foil 751, any material that is stable relative to the redox reaction during charging and discharging, such as nickel, iron, stainless steel, titanium, calcined carbon, conductive polymers, conductive glass, Al-Cd alloys, etc., can be appropriately used. As for the positive active material used in the positive active material layer 742 and the negative active material used in the negative active material layer 752, any positive active material and negative active material that can absorb and release charge and transport ions can be appropriately used.

[0066] As positive electrode active materials, polyanionic compounds such as LiMPO4, LiMSiO4, and LiMBO3 (where M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), lithium titanate, LiMn2O4, or LiMn can be used. 1.5 Ni 0.5 Spinel-type lithium manganese oxides such as O4, and lithium transition metal oxides such as LiMO2 (where M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.). As negative electrode active materials, in addition to lithium metal and lithium alloys (lithium-silicon, lithium-aluminum, lithium-lead, lithium-tin, lithium-aluminum-tin, lithium-gallium, and Wood's alloys, etc.), alloys capable of absorbing and releasing lithium, carbon materials (graphite, difficult-to-graphitize carbon, easily-graphitize carbon, low-temperature sintered carbon, amorphous carbon, etc.), silicon oxides, metal oxides, and lithium metal oxides (Li4Ti5O) are also listed. 12 Compounds of transition metals and elements from groups 14 to 16, such as polyphosphate compounds, or compounds of transition metals and elements from groups 14 to 16, which are generally referred to as the negative electrode of the conversion.

[0067] The insulating element 760 (including insulating elements 761 and 762) is a microporous insulating sheet containing resin or the like. As the material for the insulating element 760, any known material can be used as long as it does not impair the performance of the energy storage element 10. Examples of insulating elements 760 include woven fabric, nonwoven fabric, and porous resin membrane. Among these examples, porous resin membrane is preferred from the viewpoint of strength, and nonwoven fabric is preferred from the viewpoint of electrolyte retention. As the material for the insulating element 760, polyolefins such as polyethylene and polypropylene are preferred from the viewpoint of cut-off function, and polyimide and aromatic polyamide are preferred from the viewpoint of resistance to oxidative decomposition. Materials composed of these resins can also be used as the insulating element 760. Insulating elements 761 and 762 can be formed from the same material or from different materials.

[0068] 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 as described above. 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 3(b), etc.). In this embodiment, the electrode body 700 is a wound-type electrode body formed by winding the positive electrode plate 740 and negative electrode plate 750 around a winding axis L extending along the X-axis direction (first direction). The winding axis L refers to an imaginary axis that serves as the central axis when winding the positive electrode plate 740 and negative electrode plate 750; in this embodiment, it is a straight line parallel to the X-axis direction passing through the center of the electrode body 700.

[0069] Specifically, the electrode body 700 winds the positive electrode plate 740 and the negative electrode plate 750 separately along the winding axis L (winding axis direction, which is the X-axis direction in this embodiment) with the spacers 761 and 762 in a staggered manner. At the ends of the positive electrode plate 740 and the negative electrode plate 750 in their respective staggered directions, there are active material non-forming portions 720 where the positive electrode active material layer 742 and the negative electrode active material layer 752 are not formed (coated), thus exposing the positive electrode current collector foil 741 and the negative electrode current collector foil 751. In other words, at one end of the electrode body 700 in the winding axis direction, there is a positive electrode active material non-forming portion 720 where the ends of the positive electrode current collector foil 741 are stacked and bundled, and at the other end of the winding axis direction, there is a negative electrode active material non-forming portion 720 where the ends of the negative electrode current collector foil 751 are stacked and bundled.

[0070] Thus, the electrode body 700 includes: an electrode body main body portion 710 constituting the main body of the electrode body 700; and a pair of (positive and negative) active material non-forming portions 720 protruding from the electrode body main body portion 710 in the X-axis direction. The electrode body main body portion 710 is a long cylindrical portion formed by winding the active material forming portion 713 and the separator 760 of the electrode plates (positive electrode plate 740 and negative electrode plate 750). The active material forming portion 713 is a portion on which an active material layer (positive electrode active material layer 742 and negative electrode active material layer 752) is formed (coated) on the current collector foil (positive electrode current collector foil 741 and negative electrode current collector foil 751) in the electrode plates (positive electrode plate 740 and negative electrode plate 750) in a second direction orthogonal to the first direction (the Y-axis direction in FIG. 3(b)). Therefore, the electrode body 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 3(a)). In other words, the electrode body 700 has curved portions 711 and flat portions 712 formed by winding the positive electrode plate 740 and the negative electrode plate 750 around the winding shaft L.

[0071] The curved portion 711 is a curved section that bends into a semi-circular arc shape from the X-axis direction towards the Z-axis direction and extends along the X-axis direction. It is arranged opposite to the bottom wall portion 113 and the lid 120 of the container body 110. That is, a pair of curved portions 711 are curved portions that bend towards the bottom wall portion 113 of the container body 110 and the lid 120 on both sides of the Z-axis direction when viewed from the X-axis direction. The flat portion 712 is a rectangular and flat portion that connects the ends of the pair of curved portions 711 to each other and extends parallel to the XZ plane in the Y-axis direction. It is arranged opposite to the long side wall portions 111 on both sides of the container body 110 in the Y-axis direction. The curvature of the curved portion 711 is not limited to a semi-circular arc shape; it can also be part of an ellipse, etc., and can be curved in any way. The flat portion 712 is not limited to having a flat outer surface in the Y-axis direction; the outer surface can also be slightly concave or slightly convex.

[0072] According to the structure described above, the electrode body 700 has a long (horizontally elongated) shape with a relatively long length in the winding axis direction (X-axis direction). That is, the length of the electrode body 700 in the X-axis direction is longer than the length in either the Y-axis or Z-axis direction. In this embodiment, the length of the electrode body 700 in the X-axis direction is preferably 300 mm or more, more preferably 500 mm or more, and even more preferably 1000 mm or more, but it may be shorter than 300 mm. In this embodiment, the length of the electrode body 700 in the X-axis direction is 1500 mm or less, but it may be longer than 1500 mm.

[0073] Further, as shown in FIG4, a plurality of electrode holes 731 are formed in the active material forming portion 713 of the electrode body main body portion 710 of the electrode body 700. In FIG2 and FIG3, the electrode holes 731 are not shown because they are hidden by the isolation member 760. In FIG4, the electrode holes 731 hidden by the isolation member 760 are shown in dashed lines. FIG4 is a schematic diagram showing the arrangement and shape of the electrode holes 731, etc., and the size of the electrode holes 731 is shown larger than the actual size compared with FIG5 and the like described later. In this embodiment, when viewed through the electrode plates (positive electrode plate 740 and negative electrode plate 750) and the isolation member 760 of the electrode body 700, the plurality of electrode holes 731 are densely arranged in a given area in the Y-axis direction, thereby forming an electrode hole group 730 composed of the plurality of electrode holes 731 (see FIG5). The structure of electrode hole 731 and electrode hole group 730 will be described in detail below using Figures 5 and 6.

[0074] [2.2 Description of electrode hole 731 and electrode hole group 730]

[0075] Figure 5 is a front view showing the structure of the electrode holes 731 and the electrode hole group 730 of the electrode body 700 according to this embodiment. Figure 5(a) is a view of the electrode body 700 viewed from the negative Y-axis direction, and Figure 5(b) shows an enlarged view of the structure of the electrode holes 731 and the electrode hole group 730. In Figure 5, for ease of explanation, the electrode plates (positive electrode plate 740 and negative electrode plate 750) and the separator 760 of the electrode body 700 are shown in perspective, illustrating each electrode hole 731 and each electrode hole group 730 formed in the flat portion 712 in the negative Y-axis direction of the electrode body main body 710. Figure 6 is a front view and a cross-sectional view showing an enlarged view of a portion of the structure of the electrode holes 731 and the electrode hole group 730 of the electrode body 700 according to this embodiment. Figure 6(a) is a front view of the structure of a portion of the electrode hole 731 and electrode hole group 730 viewed from the negative Y-axis direction, and Figure 6(b) is a cross-sectional view showing section VIb-VIb in Figure 6(a). Other electrode holes 731 and electrode hole groups 730 not shown in Figure 6 also have the same structure as those shown in Figure 6.

[0076] As described above, the electrode body 700 includes an active material forming portion 713 in which an active material layer is formed in the second direction (Y-axis direction in FIG. 6) of the current collector foil. The electrode includes a positive electrode plate 740 and a negative electrode plate 750. Therefore, the positive electrode plate 740 includes a positive electrode active material forming portion 713 in which a positive electrode active material layer 742 is formed in the second direction (Y-axis direction in FIG. 6) of the positive electrode current collector foil 741, and the negative electrode plate 750 includes a negative electrode active material forming portion 713 in which a negative electrode active material layer 752 is formed in the second direction (Y-axis direction in FIG. 6) of the negative electrode current collector foil 751. In other words, the positive electrode current collector foil 741 and the positive electrode active material layer 742 in the positive electrode plate 740, excluding the positive electrode active material non-forming portion 720, are referred to as the positive electrode active material forming portion 713. The negative electrode current collector foil 751 and the negative electrode active material layer 752, excluding the non-formed portion 720 of the negative electrode active material in the negative electrode plate 750, are referred to as the active material forming portion 713 of the negative electrode. In other words, the portion of the positive electrode plate 740 excluding the non-formed portion 720 of the positive electrode active material is referred to as the active material forming portion 713 of the positive electrode, and the portion of the negative electrode plate 750 excluding the non-formed portion 720 of the negative electrode active material is referred to as the active material forming portion 713 of the negative electrode.

[0077] In this embodiment, since the electrode plates (positive electrode plate 740 and negative electrode plate 750) are wound, the active material forming portion 713 is also wound. Therefore, as shown in FIG6, the active material forming portion 713 forms multiple layers 713a in the Y-axis direction (second direction). In other words, the active material forming portion 713 has multiple layers 713a stacked in the Y-axis direction (second direction). Specifically, in the positive electrode plate 740, three layers of positive electrode active material layer 742 (two layers) formed on both sides of the positive electrode current collector foil 741 (one layer) in the Y-axis direction are considered as one unit, referred to as one layer 713a (positive electrode layer 713a). In the negative electrode plate 750, three layers of negative electrode active material layer 752 (two layers) formed on both sides of the negative electrode current collector foil 751 (one layer) in the Y-axis direction are considered as one unit, referred to as one layer 713a (negative electrode layer 713a). In this way, by winding the positive electrode plate 740 and the negative electrode plate 750, multiple positive electrode layers 713a and multiple negative electrode layers 713a are stacked with spacers 761 or 762 disposed between the positive electrode layer 713a and the negative electrode layer 713a. The electrode body main body 710 is formed by stacking these multiple positive electrode layers 713a, multiple negative electrode layers 713a, and spacers 761 and 762.

[0078] Each of two or more consecutive layers 713a among the multiple layers 713a has one or more electrode holes 731 serving as through holes connecting both the current collector foil and the active material layer. In Figure 6, four consecutive layers 713a (two positive electrode layers 713a and two negative electrode layers 713a) are shown. The two positive electrode layers 713a each have one or more electrode holes 731 serving as through holes connecting both the positive electrode current collector foil 741 and the positive electrode active material layer 742 (three positive electrode holes 740a in Figure 6). The positive electrode holes 731 (electrode holes 740a) are circular through holes that connect the positive electrode current collector foil 741 and the positive electrode active material layer 742 disposed on both sides of the positive electrode current collector foil 741 in the Y-axis direction in the Y-axis direction. Each of the two negative electrode layers 713a has one or more electrode holes 731 (three negative electrode holes 750a in Figure 6) serving as through holes connecting both the negative electrode current collector foil 751 and the negative electrode active material layer 752. The negative electrode hole 731 (electrode hole 750a) is a circular through hole that connects the negative electrode current collector foil 751 and the negative electrode active material layer 752 disposed on both sides of the negative electrode current collector foil 751 in the Y-axis direction. The shape of the electrode hole 731 (electrode hole 740a, electrode hole 750a) is not limited to a circular shape; any shape is acceptable, such as an ellipse, oblong shape, rectangle, polygonal shape, or slit.

[0079] The opening area of ​​electrode hole 731 (electrode hole 740a, electrode hole 750a) is 0.02 mm.2 The following applies. If the electrode hole 731 is circular, its diameter is 0.16 mm or less (radius 0.08 mm or less). With an electrode hole 731 of this size, even if two adjacent electrode holes 731 are connected, the resulting opening area is 0.04 mm². 2 Even with a small electrode hole (or an electrode hole with a width of 0.16 mm and a length of 0.32 mm), it is still relatively small, thus less prone to defects such as lithium battery crystallization. In contrast, with an opening area greater than 0.02 mm²... 2 In the case of electrode holes, if two adjacent electrode holes are connected, there is a concern about adverse conditions such as lithium battery crystallization. The opening area of ​​electrode hole 731 is preferably 0.01 mm². 2 Below (or below 100 μm in diameter), more preferably 0.002 mm. 2 Below (or below 50 μm in diameter), 0.0003 mm is more preferably preferred. 2 Below (or below 20μm in diameter).

[0080] From the viewpoint of electrolyte permeability to electrode body 700, the opening area of ​​electrode hole 731 is preferably 0.00002 mm. 2 The diameter is 5 μm or more. The opening area of ​​the electrode hole 731 is more preferably 0.00005 mm². 2 The diameter is 10 μm or more, and more preferably 0.0002 mm. 2 The diameter is 15 μm or more. The method for forming (processing) the electrode hole 731 is not particularly limited, but by using a high-output-density ultrashort pulse laser such as a picosecond laser or femtosecond laser, electrode holes 731 with small opening areas (small diameters) can be processed. The separator 760 disposed between two or more consecutive layers 713a (adjacent positive electrode plates 740 and negative electrode plates 750) has microporous structures, facilitating the permeation of electrolyte and the venting of gas within the separator 760. Therefore, through holes may not be formed in the separator 760. If the microporous structures are considered as through holes, it can also be said that through holes are disposed in the separator 760 between two or more consecutive layers 713a. Therefore, in this embodiment, through holes like the electrode hole 731 are not formed in the separator 760, but through holes like the electrode hole 731 may be formed in the separator 760 (one or both of separators 761 and 762). When the through hole is formed in the isolator 760, the configuration of the through hole in the isolator 760 can be within or outside the range of the electrode hole group 730.

[0081] In this embodiment, the three electrode holes 740a disposed in the positive electrode layer 713a and the three electrode holes 750a disposed in the negative electrode layer 713a, viewed from the Y-axis direction, are positioned at different locations offset from each other in the X-axis and Z-axis directions. Any one of the three electrode holes 740a and any one of the three electrode holes 750a may also be positioned at the same location (partially or completely overlapping) in one or both of the X-axis and Z-axis directions when viewed from the Y-axis direction. The same applies to the three electrode holes 740a and three electrode holes 750a disposed in the positive electrode layer 713a and the negative electrode layer 713a, which are separated by the separator 762. The same applies to the electrode holes 740a in different positive electrode layers 713a and the electrode holes 750a in different negative electrode layers 713a. In other words, when viewed from the Y-axis direction, electrode holes 731 set in two or more consecutive layers 713a can be configured in the same position or in offset positions (partially overlapping or separated positions).

[0082] In this way, electrode holes 731 are formed in multiple layers 713a of the active material forming portion 713. By stacking multiple layers 713a, an electrode hole group 730 is formed in the electrode body 700, as shown in FIG. 5. Specifically, in the electrode body 700, viewed from the Y-axis direction (second direction), each layer 713a covering two or more layers 713a forms an electrode hole group 730 in which the electrode holes 731 of each layer 713a are densely arranged within a given region R1. In other words, in the electrode hole group 730, viewed from the Y-axis direction, the electrode holes 731 of each layer 713a are concentrated (concentrated) within the given region R1. That is, the electrode holes 731 are denser (concentrated) within the given region R1 compared to the surrounding area of ​​the given region R1. The density of electrode holes 731 is higher (the number of electrode holes 731 per unit area) within the given region R1 compared to the surrounding area of ​​the given region R1.

[0083] In this embodiment, viewed from the Y-axis direction (second direction), the maximum width of the given region R1 is less than 50 mm. The given region R1 is a region with a diameter smaller than that of region R2, which is 50 mm. In Figure 5, the width of the given region R1 in the Z-axis direction is the longest, less than 50 mm. That is, the width of the given region R1 in the Z-axis direction is longer than the width of the given region R1 in the X-axis direction. Therefore, even if the electrode plates (positive electrode plate 740 and negative electrode plate 750) are wound and the position of the electrode holes 731 is deviated in the Z-axis direction, multiple electrode holes 731 can be arranged within the given region R1 (the electrode plates can be wound without high precision). In this embodiment, the electrode hole group 730 is a roughly elliptical shape that is longer in the Z-axis direction when viewed from the Y-axis direction. When viewed from the Y-axis direction, the electrode hole group 730 can also be circular, polygonal, or any other shape. By adjusting the formation position of the electrode holes 731, the width of the given region R1 in the Z-axis direction can be made shorter than the width of the given region R1 in the X-axis direction. The maximum width of the given region R1 is preferably 30 mm or less, more preferably 10 mm or less, and even more preferably 5 mm or less. The minimum width of the given region R1 is preferably 0.1 mm or more, more preferably 1 mm or more, and even more preferably 2 mm or more.

[0084] As shown in Figures 4 to 6, in the electrode hole group 730, each of two or more consecutive layers 713a has multiple electrode holes 731 (three electrode holes 731 in this embodiment). In Figure 6, each layer 713a of the positive electrode has three electrode holes 740a, and each layer 713a of the negative electrode has three electrode holes 750a. Further, in the electrode hole group 730, electrode holes 731 are provided in all layers 713a of the positive electrode plate 740 and the negative electrode plate 750. Specifically, in the electrode hole group 730, electrode holes 731 are provided in all layers 713a of the active material forming portion 713 of the positive electrode plate 740 and all layers 713a of the active material forming portion 713 of the negative electrode plate 750. In other words, in the electrode hole group 730, multiple electrode holes 731 are provided in all layers 713a of the positive electrode plate 740 and the negative electrode plate 750.

[0085] Two or more electrode hole groups 730 are formed in the electrode body 700. In this embodiment, nine electrode hole groups 730 (electrode hole groups 730a to 730i) are formed in each flat portion 712 of the electrode body main body 710 of the electrode body 700. Specifically, in the flat portion 712 in the negative Y-axis direction of the electrode body main body 710, at the end of the negative X-axis direction of the electrode body main body 710, electrode hole groups 730a, 730b, and 730c are arranged along the Z-axis direction. In the central portion in the X-axis direction of the electrode body main body 710, electrode hole groups 730d, 730e, and 730f are arranged along the Z-axis direction. At the end of the positive X-axis direction of the electrode body main body 710, electrode hole groups 730g, 730h, and 730i are arranged along the Z-axis direction. In other words, at the positive Z-axis end of the electrode body 710, electrode hole groups 730a, 730d, and 730g are arranged along the X-axis. At the central part of the electrode body 710 in the Z-axis direction, electrode hole groups 730b, 730e, and 730h are arranged along the X-axis. At the negative Z-axis end of the electrode body 710, electrode hole groups 730c, 730f, and 730i are arranged along the X-axis.

[0086] The arrangement of the nine electrode hole groups 730 (electrode hole groups 730a to 730i) formed in the flat portion 712 in the positive Y-axis direction and the flat portion 712 in the negative Y-axis direction of the electrode body 710 is reversed (the positions in the Z-axis direction are opposite). That is, in the flat portion 712 in the positive Y-axis direction of the electrode body 710, at the end of the electrode body 710 in the negative Z-axis direction, electrode hole groups 730a, 730d, and 730g are arranged along the X-axis direction, and at the end of the electrode body 710 in the positive Z-axis direction, electrode hole groups 730c, 730f, and 730i are arranged along the X-axis direction. Each electrode hole group 730 formed in the flat portion 712 in the negative Y-axis direction of the electrode body 710 has the same structure as each electrode hole group 730 formed in the flat portion 712 in the positive Y-axis direction of the electrode body 710. Figure 5 shows nine electrode hole groups 730 (electrode hole groups 730a to 730i) formed in the flat portion 712 in the negative Y-axis direction of the electrode body 710. The nine electrode hole groups 730 will be described below.

[0087] In each of these nine electrode hole groups 730 (electrode hole groups 730a to 730i), the electrode holes 731 (electrode holes 731a to 731i) provided in each layer 713a are densely arranged within a given region R1. Thus, because the electrode holes 731 are densely packed within each electrode hole group 730, the distance between the electrode holes 731 within each electrode hole group 730 is smaller than the distance between two adjacent electrode hole groups 730 (the first distance A1 or the second distance A2, etc., described later). In other words, when viewed from the Y-axis direction (second direction) (perspective view), the distance between the electrode holes 731 within each electrode hole group 730 is smaller than the distance between two adjacent electrode hole groups 730. In Figures 4 and 5, in the electrode hole groups 730a to 730i, the electrode holes 731a to 731i are densely arranged in the same configuration position. However, the electrode holes 731a to 731i only need to be densely arranged when forming the electrode body 700, and their respective configuration positions are not particularly limited.

[0088] The distance between two adjacent electrode hole groups 730 in the X-axis direction (first direction) is defined as the first distance A1. The distance between two adjacent electrode hole groups 730 in the Z-axis direction (a third direction orthogonal to the first and second directions) is defined as the second distance A2. The distance between two electrode hole groups 730 in the X-axis direction refers to the distance in the X-axis direction between the positive X-axis edge of the electrode hole group 730 in the negative X-axis direction and the negative X-axis edge of the electrode hole group 730 in the positive X-axis direction. The same applies to the distance between two electrode hole groups 730 in the Z-axis direction.

[0089] In other words, when considering a given pair of adjacent electrode hole groups 730 (9 electrode hole groups 730 in this embodiment) as objects, the distance in the X-axis direction between the two electrode hole groups 730 is defined as the first distance A1, and the distance in the Z-axis direction is defined as the second distance A2. In Figure 5, as an example of two adjacent electrode hole groups 730, electrode hole groups 730a and 730e are used as objects, and the distance in the X-axis direction between electrode hole groups 730a and 730e is defined as the first distance A1, and the distance in the Z-axis direction is defined as the second distance A2. As another example of two adjacent electrode hole groups 730, electrode hole groups 730a and 730d are used as objects, the distance in the X-axis direction between electrode hole groups 730a and 730d is the first distance A1 shown in Figure 5, but the second distance A2 in the Z-axis direction is zero.

[0090] In this structure, the first distance A1 is greater than the second distance A2. Specifically, the first distance A1 is more than 10 times the second distance A2. The first distance A1 is more preferably more than 20 times the second distance A2, and even more preferably more than 50 times the second distance A2. In this embodiment, the first distance A1 is 100 mm or more. The first distance A1 is preferably 125 mm or more, and even more preferably 150 mm or more. From the viewpoint of the permeability of the electrolyte to the electrode body 700, it is preferable that the first distance A1 is 90 times or less than the second distance A2, and even more preferably 70 times or less. The first distance A1 is preferably 250 mm or less, and even more preferably 200 mm or less. Thus, the plurality of electrode hole groups 730 (9 electrode hole groups 730 in this embodiment) have two electrode hole groups 730 with a relationship where the first distance A1 is greater than the second distance A2 (greater than 10 times the second distance A2, etc.).

[0091] In this embodiment, among the nine electrode hole groups 730, three electrode hole groups 730 arranged at intervals of a first distance A1 in the X-axis direction and at intervals of a second distance A2 in the Z-axis direction are arranged in a grid pattern. Therefore, the distance between any two adjacent electrode hole groups 730 in the X-axis direction is defined as the first distance A1, and the distance between any two adjacent electrode hole groups 730 in the Z-axis direction is defined as the second distance A2. It can also be said that the first distance A1 is greater than the second distance A2. In FIG. 5, the distance in the X-axis direction between adjacent electrode hole groups 730a and 730d is the first distance A1, and the distance in the Z-axis direction between adjacent electrode hole groups 730a and 730b is the second distance A2. The first distance A1 is greater than the second distance A2. Thus, the plurality of electrode hole groups 730 (in this embodiment, there are 9 electrode hole groups 730) have at least 3 electrode hole groups 730 with a relationship that the first distance A1 is greater than the second distance A2 (greater than 10 times the second distance A2, etc.).

[0092] Because electrode holes 730 (electrode holes 731) are formed in the electrode body 700, the effective electrode area of ​​the electrode body 700 is reduced, and the capacity of the energy storage element 10 is reduced (resulting in capacity loss). The effective electrode area of ​​the electrode body 700 refers to the area of ​​the region in the electrode plate where the active material layer is disposed (the region where the active material forming portion 713 is disposed). The proportion by which this effective electrode area is reduced is called the opening area ratio. The opening area ratio is the ratio of the total opening area of ​​all the electrode holes 731 provided in the active material forming portion 713 to the area of ​​the active material forming portion 713. More specifically, the opening area ratio is the ratio of the total opening area of ​​all the electrode holes 731 provided in the active material forming portion 713 to the area of ​​the active material forming portion 713 when the electrode body 700 is unfolded in a wound state and the electrode plate is expanded and viewed from above.

[0093] From the viewpoint of suppressing the reduction in capacity of the energy storage element 10, the opening area ratio is preferably 3% or less, more preferably 1% or less, and even more preferably 0.5% or less. From the viewpoint of improving the permeability of the electrolyte to the electrode body 700, the opening area ratio is preferably 0.001% or more, more preferably 0.01% or more. As mentioned above, the opening area ratio can also be described as the ratio of the amount of capacity reduction (capacity loss) of the energy storage element 10 caused by the electrode hole 731. Therefore, the ratio of the amount of capacity reduction (capacity loss) of the energy storage element 10 is also preferably 3% or less, more preferably 1% or less, and even more preferably 0.5% or less. The ratio of the amount of capacity reduction (capacity loss) of the energy storage element 10 is preferably 0.001% or more, more preferably 0.01% or more.

[0094] [3. Explanation of the effect]

[0095] As described above, in the energy storage element 10 according to the embodiment of the present invention, each of the two or more consecutive layers 713a formed by the active material forming portions 713 of the wound electrode plates (positive electrode plate 740 and negative electrode plate 750) of the electrode body 700 has an opening area of ​​0.02 mm. 2The electrode holes 731 are shown below. In the electrode body 700, viewed from the second direction (Y-axis direction), a dense group of electrode holes 730, each layer 713a of which is formed, is formed within a given region R1. While an electrode body 700 with wound electrodes is difficult for electrolyte to penetrate, the electrode hole group 730, where each layer 713a of the active material forming portion 713 is formed, allows electrolyte to easily penetrate into the electrode body 700 through each electrode hole 731 of the electrode hole group 730. The electrode body 700 has a long strip shape with a relatively long length in the winding axis direction (X-axis direction), making electrolyte penetration difficult. However, as described above, by forming the electrode hole group 730 in the electrode body 700, electrolyte can easily penetrate into the electrode body 700. Since the electrode hole 731 has an opening area of ​​0.02 mm... 2 The tiny electrode holes 731 described below can suppress the risk of micro-short circuits caused by burrs or contaminants, or the reduction in capacity (energy density) caused by the reduction in effective electrode area. Thus, electrolyte can easily penetrate the electrode body 700 while suppressing adverse conditions.

[0096] When the energy storage element 10 is in use and gas is generated and accumulated inside the electrode body 700, the gas can be vented from the electrode aperture group 730 (especially electrode aperture groups 730a, 730d, and 730g), thus suppressing capacity reduction caused by the expansion of inactive areas due to gas accumulation. When the electrolyte inside the electrode body 700 is consumed and electrolyte depletion occurs, electrolyte can be replenished to the inside of the electrode body 700 from the electrode aperture group 730 (especially electrode aperture groups 730c, 730f, and 730i), thus suppressing capacity reduction caused by the expansion of inactive areas due to liquid depletion at the end of its lifespan.

[0097] Because the electrode hole 731 is a tiny through-hole, lithium-ion crystallization is unlikely to occur even without proper alignment of the electrode hole 731. In other words, even without a negative electrode active material opposite the positive electrode active material, crystallization is unlikely to occur. Even assuming tiny crystallization occurs, it is localized, and therefore, during the use of the energy storage element 10, the possibility of eliminating crystallization due to the self-diffusion of lithium ions in the electrode plate is high. When the tiny electrode hole 731 is formed using a laser (picosecond laser or femtosecond laser, etc.), the components of the electrode plate evaporate, thus reducing the likelihood of the formation of contaminants with a size of tens of micrometers that could potentially cause micro-short circuits. When the tiny electrode hole 731 is formed on the electrode plate, the thermal impact from the laser is minimal, thus suppressing the deterioration of the surrounding active material due to heat. When an electrode hole 731 with a diameter of 5 μm or more is formed, the electrolyte can more easily penetrate into the electrode body 700. Holes with a diameter of 5 μm or more can be formed using a laser (picosecond laser or femtosecond laser, etc.). By forming tiny electrode holes 731 on the electrode plate, it is possible to prevent the slurry from contaminating the support roller through the electrode holes 731 during the coating of the active material, thus enabling stable coating.

[0098] By making the size of a given region R1 less than 50 mm in which the electrode holes 731 of each layer 713a in the electrode hole group 730 are densely arranged, the permeability of the electrolyte through the electrode holes 731 to each layer 713a can be improved because the electrode holes 731 of each layer 713a are close together. The permeability of the electrolyte can also be improved if two or more electrode holes 731 in one layer 713a are close to each other, and the permeability of the electrolyte can also be improved if the electrode holes 731 of two or more adjacent layers 713a are close to each other. If the number of electrode holes 731 can be reduced by making the electrode holes 731 densely arranged within a small given region R1, the reduction of the effective electrode area can be suppressed.

[0099] By providing multiple electrode holes 731 in each layer 713a of the electrode hole group 730, electrolyte can be efficiently permeated into each layer 713a through the multiple electrode holes 731. By providing multiple electrode holes 731 in each layer 713a, gas generated inside the electrode body 700 can be efficiently vented from the electrode hole group 730, and electrolyte can be efficiently replenished into the electrode body 700 from the electrode hole group 730 when the generated electrolyte is depleted.

[0100] In the electrode hole group 730, by providing electrode holes 731 in all layers 713a of the active material forming portion 713 provided in the positive electrode plate 740 and the negative electrode plate 750, electrolyte can permeate into all layers 713a of the positive electrode plate 740 and the negative electrode plate 750, thus enabling more efficient permeation of electrolyte into the electrode body 700. By providing electrode holes 731 in all layers 713a of the positive electrode plate 740 and the negative electrode plate 750, gas generated inside the electrode body 700 can be more effectively vented from the electrode hole group 730, and electrolyte can be more effectively replenished into the electrode body 700 from the electrode hole group 730 when the generated electrolyte is depleted.

[0101] By reducing the ratio of the total opening area of ​​all electrode holes 731 to the area of ​​the active material forming portion 713 to 3% or less, the reduction in effective electrode area caused by the provision of electrode holes 731 in the active material forming portion 713 can be suppressed. Reducing the ratio of the total opening area of ​​the electrode holes 731 reduces either the opening area of ​​the electrode holes 731 or the number of electrode holes 731, thereby reducing the risk of micro-short circuits caused by burrs or contaminants.

[0102] Viewed from the second direction (Y-axis direction), the distance between the electrode holes 731 within the electrode hole group 730 is smaller than the distance between two adjacent electrode hole groups 730. This smaller distance allows the electrolyte to effectively penetrate into the electrode body 700. Viewed from the second direction (Y-axis direction), the distance between two adjacent electrode hole groups 730 is greater than the distance between the electrode holes 731 within the electrode hole group 730. This larger distance helps to suppress damage to the electrode plates (positive electrode plate 740 or negative electrode plate 750) between the two electrode hole groups 730.

[0103] The first distance A1 between the two groups of electrode holes 730 in the first direction (X-axis direction) is made greater than the second distance A2 between the two groups of electrode holes 730 in the third direction (Z-axis direction). In this way, by distributing the electrode holes 730 at a fixed distance (the first distance A1 in the first direction and the second distance A2 in the third direction), the reduction in the effective electrode area caused by the provision of the electrode holes 731 can be suppressed. By increasing the distance between the groups of electrode holes 730 in the first direction (X-axis direction) (the first distance A1), damage to the electrode plates (positive electrode plate 740 or negative electrode plate 750) between the electrode holes 730 can be further suppressed. In particular, since the electrode body 700 is formed by winding the electrode plates (positive electrode plate 740 and negative electrode plate 750), the electrode plates are wound while being stretched in the second direction (Y-axis direction) perpendicular to the winding axis L. Therefore, if the distance between the electrode hole groups 730 in the first direction (X-axis direction) (first distance A1) is small, the tension will be concentrated in the active material forming part 713 between adjacent electrode hole groups 730, which is prone to breakage. Therefore, by increasing the first distance A1, damage to the electrode plates, such as electrode plate breakage, between the electrode hole groups 730 can be more effectively suppressed.

[0104] By making the first distance A1 greater than 10 times the second distance A2, the electrode hole group 730 is distributed at larger intervals in the first direction (X-axis direction), thus further suppressing the reduction in effective electrode area caused by the provision of electrode holes 731. By making the first distance A1 greater than 10 times the second distance A2, the distance between the electrode hole group 730 in the first direction (X-axis direction) is further increased, thus further suppressing damage to the electrode plates (positive electrode plate 740 or negative electrode plate 750) between the electrode hole group 730.

[0105] [4. Explanation of variations]

[0106] The energy storage element 10 according to the embodiments of the present invention has been described above, but the present invention is not limited to the above embodiments. The embodiments disclosed herein are illustrative in all aspects, and within the scope of the present invention, there is an equivalent meaning to the scope of the patent claims and all modifications within that scope.

[0107] (Variations 1-5)

[0108] In the above embodiments, the number and position of the electrode holes 731 and the electrode hole group 730 formed in the electrode body 700 are not particularly limited. That is, it is possible to form a number of electrode hole groups 730 at any position in the electrode body 700, and a number of electrode holes 731 at any position within the electrode hole group 730.

[0109] Figure 7 is a front view showing the structure of the electrode hole 731 and electrode hole group 730 of the electrode body 701 according to Modification 1 of this embodiment. Figure 8 is a front view showing the structure of the electrode hole 731 and electrode hole group 730 of the electrode body 702 according to Modification 2 of this embodiment. Figure 9 is a front view showing the structure of the electrode hole 731 and electrode hole group 730 of the electrode body 703 according to Modification 3 of this embodiment. Figure 10 is a front view showing the structure of the electrode hole 731 and electrode hole group 730 of the electrode body 704 according to Modification 4 of this embodiment. Figures 7 to 10 are corresponding to Figure 5(a). In Figures 7 to 10, similar to Figure 5, for ease of explanation, perspective views are provided of the electrode plates (positive electrode plate 740 and negative electrode plate 750) and the separator 760 of the electrode bodies 701 to 704, showing the electrode holes 731 and electrode hole groups 730 formed in the flat portion 712 in the negative Y-axis direction of the electrode body main body 710. In various modifications, the flat portion 712 in the positive Y-axis direction of the electrode body main body 710 also has electrode holes 731 and electrode hole groups 730 with the same structure as the flat portion 712 in the negative Y-axis direction of the electrode body main body 710. Figure 11 is a perspective view showing the structure of the electrode holes 731 in the electrode hole group 730 of the electrode body 705 according to Modification 5 of this embodiment. Figure 11 corresponds to Figure 4.

[0110] As shown in Figure 7, in the electrode body 701 of Modified Example 1, three electrode hole groups 730 (electrode hole groups 730a, 730d, and 730g) are formed at the positive Z-axis end of the electrode body 700 in the above embodiment. In this modified example, in the flat portion 712 in the negative Y-axis direction, the distance in the X-axis direction between two adjacent electrode hole groups 730 (electrode hole groups 730a and 730d in Figure 7), i.e., the first distance A1, is also greater than the distance in the Z-axis direction, i.e., the second distance A2 (not shown since it is zero) (greater than 10 times the second distance A2). The same applies to the flat portion 712 in the positive Y-axis direction. Other structures in this modified example are the same as those in the above embodiment, so detailed descriptions are omitted. According to this modified example, the same effects as the above embodiment can be achieved. In particular, by reducing the number of electrode holes 730, it is possible to suppress adverse conditions such as the risk of micro-short circuits caused by burrs or contaminants associated with the formation of electrode holes 731, or capacity reduction caused by the reduction of effective electrode area. When the energy storage element 10 is in use and gas is generated and accumulated inside the electrode body 701, since the gas can be vented from the electrode holes 730, it is possible to suppress capacity reduction caused by the expansion of inactive areas due to gas accumulation.

[0111] As shown in Figure 8, in the electrode body 702 of Modified Example 2, three electrode hole groups 730 (electrode hole groups 730c, 730f, and 730i) are formed at the negative Z-axis end of the electrode body 700 in the above embodiment. In this modified example, in the flat portion 712 in the negative Y-axis direction, the distance in the X-axis direction between two adjacent electrode hole groups 730 (electrode hole groups 730c and 730f in Figure 8), i.e., the first distance A1, is also greater than the distance in the Z-axis direction, i.e., the second distance A2 (not shown since it is zero) (greater than 10 times the second distance A2). The same applies to the flat portion 712 in the positive Y-axis direction. Other structures in this modified example are the same as those in the above embodiment, so detailed descriptions are omitted. According to this modified example, the same effects as those in the above embodiment can be achieved. In particular, by reducing the number of electrode apertures 730, it is possible to suppress adverse conditions such as the risk of micro-short circuits caused by burrs or contaminants associated with the formation of electrode apertures 731, or capacity reduction due to the reduction in effective electrode area. When the electrolyte inside the electrode body 702 is consumed and electrolyte depletion occurs, electrolyte can be replenished to the inside of the electrode body 702 from the electrode apertures 730, thus suppressing capacity reduction caused by the expansion of inactive areas due to liquid depletion at the end of its lifespan.

[0112] As shown in Figure 9, in the electrode body 703 of Modified Example 3, five groups of electrode holes 730 (electrode hole groups 730j, 730k, 730l, 730m, 730n) are formed in the flat portion 712 in the negative Y-axis direction, each having an electrode hole 731 (electrode hole 731j, 731k, 731l, 731m, 731n). These five groups of electrode holes 730 are arranged along the X-axis direction, and their positions in the Z-axis direction are alternately staggered (interleaved arrangement). In this modified example, the distance between two adjacent groups of electrode holes 730 in the X-axis direction (first direction) is defined as the first distance A1, and the distance between two adjacent groups of electrode holes 730 in the Z-axis direction (third direction) is defined as the second distance A2, where the first distance A1 is greater than the second distance A2. In Figure 9, taking two adjacent electrode hole groups 730 as an example, electrode hole group 730j and electrode hole group 730k are considered. The distance between electrode hole groups 730j and electrode hole group 730k in the X-axis direction is defined as the first distance A1, and the distance in the Z-axis direction is defined as the second distance A2. The first distance A1 is more than 10 times the second distance A2. The same applies to the flat portion 712 in the positive Y-axis direction. Regarding other structures of this modified example, since they are the same as those of the above embodiment, detailed descriptions are omitted. According to this modified example, the same effects as those of the above embodiment can be achieved. In particular, by reducing the number of electrode hole groups 730, it is possible to suppress the risk of micro-short circuits caused by burrs or contaminants associated with the formation of electrode holes 731, or adverse conditions such as capacity reduction caused by the reduction of effective electrode area.

[0113] As shown in Figure 10, in the electrode body 704 of Modified Example 4, three groups of electrode holes 730 (electrode hole groups 730o, 730p, and 730q) are formed in the flat portion 712 in the negative Y-axis direction, each having an electrode hole 731 (electrode hole 731o, 731p, and 731q). These three groups of electrode holes 730 are longer in the Z-axis direction and arranged along the X-axis direction. In this modified example, the distance in the X-axis direction between two adjacent groups of electrode holes 730 (electrode hole group 730o and electrode hole group 730p in Figure 10), i.e., the first distance A1, is greater than the distance in the Z-axis direction, i.e., the second distance A2 (not shown as it is zero) (greater than 10 times the second distance A2). In this modified example, each group of electrode holes 730 is formed as a strip extending along the Z-axis direction, and the width A3 of the group of electrode holes 730 in the X-axis direction is approximately 20 mm. Within each electrode hole group 730, a circular or elliptical assembly of multiple electrode holes 731 is arranged along the Z-axis direction. In each electrode hole group 730, in each layer 713a of the active material forming portion 713, only one or more electrode holes 731 as shown in FIG. 10 need to be formed; the number of electrode holes 731 can be as many as possible. In one electrode hole group 730, the multiple electrode holes 731 can also be arranged in a serrated pattern. The same applies to the flat portion 712 in the positive Y-axis direction. Other structures of this modified example are the same as those in the above embodiment, so detailed descriptions are omitted. According to this modified example, the same effects as the above embodiment can be achieved. In particular, since each electrode hole group 730 extends along the Z-axis direction, gas can be efficiently exhausted from the electrode holes 731 in the positive Z-axis direction, and electrolyte can be replenished into the interior of the electrode body 704 from the electrode holes 731 in the negative Z-axis direction.

[0114] As shown in FIG11, in the electrode body 705 of Modified Example 5, electrode holes 731 (electrode holes 731a to 731i) provided in the electrode body 700 of the above embodiment are formed. However, in this modified example, only one electrode hole 731 is formed in each layer 713a of the active material forming portion 713 of the electrode hole group 730. That is, in this modified example, any one of the three electrode holes 731 included in the electrode hole group 730 and provided in each layer 713a of the above embodiment is formed in each layer 713a. In FIG11, as in FIG4, the size of the electrode hole 731 is enlarged and illustrated. Viewed from the Y-axis direction, the electrode holes 731 formed in each layer 713a are densely packed in a given area, thereby forming the electrode hole group 730. The electrode hole group 730 formed on the electrode body 705 has the same structure as the structure shown in FIG. 5 due to the dense arrangement of electrode holes 731 in each layer 713a; therefore, the illustration and detailed description of the electrode hole group 730 are omitted. Other structures of this modified example are the same as those in the above embodiment, so detailed descriptions are omitted. According to this modified example, the same effects as in the above embodiment can be achieved. In particular, by reducing the number of electrode holes 731, it is possible to suppress the risk of micro-short circuits caused by burrs or contaminants associated with the formation of electrode holes 731, or the capacity reduction caused by the reduction of the effective electrode area.

[0115] (Variation Example 6)

[0116] The energy storage element 10 can also be used in an energy storage device. In this case, the technology of the present invention can be applied to at least one energy storage element 10 provided in the energy storage device. FIG12 is a top view showing an example of an energy storage device 30 according to a variation 6 of this embodiment. As shown in FIG12, a plurality of energy storage units 20 are arranged inside the energy storage device 30. The energy storage unit 20 is composed of a plurality of energy storage elements 10 electrically connected. The energy storage device 30 may also include a bus bar (not shown) that electrically connects a plurality of energy storage elements 10, a bus bar (not shown) that electrically connects a plurality of energy storage units 20, etc. The energy storage unit 20 or the energy storage device 30 may also include a status monitoring device (not shown) that monitors the status of one or more energy storage elements 10. The energy storage device 30 may also have only one energy storage unit 20 (that is, the energy storage unit 20 may also be called an energy storage device).

[0117] (Other variations)

[0118] In the above embodiments (and the above variations 1 to 6, hereinafter the same), the electrode hole group 730 is provided to be formed on both the flat portion 712 in the negative Y-axis direction and the flat portion 712 in the positive Y-axis direction of the electrode body main portion 710, but it is also possible to form only the flat portion 712 on either side. The structure of the electrode hole group 730 (its arrangement position, shape, number, or the number of electrode holes 731 within one electrode hole group 730, etc.) can also be different in the flat portion 712 in the negative Y-axis direction and the flat portion 712 in the positive Y-axis direction. The electrode hole group 730 can also be formed on the curved portion 711 of the electrode body main portion 710. In variation 1, the electrode hole group 730 can also be formed on the curved portion 711 in the positive Z-axis direction of the electrode body main portion 710. In variation 2, the electrode hole group 730 can also be formed on the curved portion 711 in the negative Z-axis direction of the electrode body main portion 710. When the electrode hole group 730 is formed in the bend 711, the second direction (the stacking direction of the multiple layers 713a) is not defined as the Y-axis direction, but as the Z-axis direction or the direction between the Y-axis direction and the Z-axis direction.

[0119] In the above embodiment, the plurality of electrode hole groups 730 provided on the electrode body main body 710 are all configured to have the same structure, but any one of the electrode hole groups 730 may have a different structure.

[0120] In the above embodiments, the electrode holes 731 (electrode holes 740a and 750a) are all designed to have the same shape and the same size (opening area). However, any one of the electrode holes 731 may have a different shape or a different size (opening area). The size of the electrode hole 740a may be larger or smaller than the size of the electrode hole 750a.

[0121] In the above-described embodiments, the electrode hole group 730 is provided with a plurality of electrode holes 731 in all layers 713a of the positive electrode plate 740 and the negative electrode plate 750, but it is not limited to this. Electrode holes 731 may be provided only in half of a continuous layer 713a of all layers 713a of the positive electrode plate 740 and the negative electrode plate 750, or only in one-third or one-quarter of a continuous layer 713a. Alternatively, only one electrode hole 731 may be provided in any one layer 713a of the positive electrode plate 740 and the negative electrode plate 750. In other words, it is sufficient that one or more electrode holes 731 are provided in each of two or more consecutive layers 713a of the positive electrode plate 740 and the negative electrode plate 750.

[0122] In the above embodiments, the opening area ratio can be greater than 3% if time costs are reduced during priority manufacturing.

[0123] In the above implementation, when viewed from the Y-axis direction (second direction), the maximum width of a given region R1 is set to be less than 50 mm, but it can also be greater than 50 mm.

[0124] In the above embodiment, in two adjacent electrode hole groups 730, the first distance A1 is set to be greater than 10 times the second distance A2, but it can also be less than 10 times the second distance A2 or less than the second distance A2.

[0125] In the above embodiments, only one group of electrode holes 730 may be formed in the electrode body 700.

[0126] In the above embodiment, the liquid injection section 130 is disposed on the cap 120 of the container 100, but it can also be disposed on the container body 110. The liquid injection section 130 can also be disposed on the long side wall 111 or the bottom wall 113 (the wall extending along the winding axis direction of the electrode body 700) of the container body 110, or it can be disposed on the short side wall 112. The gas discharge valve 140 is disposed on the cap 120, but it can also be disposed on any wall of the container body 110.

[0127] In the above embodiments, an inorganic coating may also be provided in the separator 760 (separator 761, 762). The inorganic coating is a coating comprising inorganic particles and an adhesive (bonding material), which allows the inorganic coating to be applied to the entirety or a portion of the surface (one or both sides) of the separator 760. Known materials can be appropriately used as the adhesive. The inorganic coating preferably includes at least one of aluminum silicate, barium sulfate, and alumina (boehmite) as the inorganic particles. Preferably, the inorganic coating has a penetration area of ​​80 mm² of electrolyte 300 seconds after the electrolyte is dropped. 2 The above applies. When a sheet-like component is disposed on the outer surface of the electrode body 700, an insulating sheet-like porous body can also be disposed. Since this porous body has pores larger than those of the separator 760 (100 μm or more), its air permeability is preferably lower than that of the separator 760 (air permeability 250 seconds / 100 mL or less). This porous body is preferably formed from a nonwoven fabric such as a polymer nonwoven fabric made of PP. Therefore, since the permeability of the electrolyte to the electrode body 700 is improved, the number of electrode pore groups 730 or electrode pores 731 formed on the electrode body 700 can be reduced.

[0128] In the above embodiment, the pair of terminals 300 are configured to both protrude from the container 100 in the positive Z-axis direction, but the protrusion direction of the terminals 300 is not particularly limited. The pair of terminals 300 may also protrude from the container 100 in either direction of the X-axis, or in both directions of the X-axis.

[0129] In the above embodiment, the electrode body 700 is configured as an elongated cylindrical shape (flat shape) having a curved portion 711 and a flat portion 712, but it can also be a cylindrical shape or an elliptical cylindrical shape, etc., as long as it is a wound electrode body, its shape is not particularly limited. In the electrode body 700, the active material non-forming portion 720 can also be a tab portion (the part of multiple tabs on which electrode plates are stacked) protruding from a part of the electrode body body portion 710. The electrode body 700 may not be a strip shape in the X-axis direction.

[0130] The invention also includes any combination of the constituent elements included in the above embodiments and their variations. The various supplementary provisions to the embodiments described above can also be applied to any of the variations 1 to 6.

[0131] Industrial availability

[0132] This invention can be applied to energy storage components such as lithium-ion secondary batteries.

[0133] Symbol Explanation

[0134] 10. Energy storage components

[0135] 20 energy storage units

[0136] 30. Energy storage device

[0137] 100 containers

[0138] 130 Liquid injection part

[0139] 300 terminal

[0140] 600 collector

[0141] Electrode bodies 700, 701, 702, 703, 704, 705

[0142] 710 Electrode Body Main Body

[0143] 711 Bending section

[0144] 712 Flat section

[0145] 713 Active substance forming part

[0146] 713a floor

[0147] 720 Non-forming part of active substance

[0148] Electrode hole groups: 730, 730a, 730b, 730c, 730d, 730e, 730f, 730g, 730h, 730i, 730j, 730k, 730l, 730m, 730n, 730o, 730p, 730q

[0149] Electrode holes 731, 731a, 731b, 731c, 731d, 731e, 731f, 731g, 731h, 731i, 731j, 731k, 731l, 731m, 731n, 731o, 731p, 731q, 740a, 750a

[0150] 740 Positive Plate

[0151] 741 Positive current collector foil

[0152] 742 Positive Electrode Active Material Layer

[0153] 750 negative electrode plate

[0154] 751 Negative electrode current collector foil

[0155] 752 Negative Electrode Active Material Layer

[0156] 760, 761, 762 Isolation components.

Claims

1. An energy storage element, characterized in that, The energy storage element includes an electrode body, which includes an electrode plate. The electrode plate includes a current-collecting foil and an active material layer. The electrode plate is wound around a winding shaft extending in a first direction, and has an active material forming portion in which the active material layer is formed in a second direction orthogonal to the first direction on the current-collecting foil. The active material forming portion forms multiple layers in the second direction. Each of two or more consecutive layers in the multiple layers includes one or more electrode holes. The electrode holes are through holes that pass through both the current-collecting foil and the active material layer, and the opening area of ​​the electrode holes is 0.02 mm². 2 Hereinafter, in the electrode body, viewed from the second direction, each of the two or more layers forms a dense group of electrode holes in a given area.

2. The energy storage element according to claim 1, characterized in that, Viewed from the second direction, the maximum width of the given area is less than 50 mm.

3. The energy storage element according to claim 1 or 2, characterized in that, In the electrode hole group, each of the two or more layers has a plurality of electrode holes.

4. The energy storage element according to claim 1 or 2, characterized in that, The electrode plate includes a positive electrode plate and a negative electrode plate. In the group of electrode holes, the electrode holes are provided in all of the multiple layers of the active material forming portion of the positive electrode plate and all of the multiple layers of the active material forming portion of the negative electrode plate.

5. The energy storage element according to claim 1 or 2, characterized in that, The total area of ​​all the electrode holes provided in the active material forming portion is 3% or less relative to the area of ​​the active material forming portion.

6. The energy storage element according to claim 1 or 2, characterized in that, In the electrode body, two or more electrode hole groups are formed. When viewed from the second direction, the distance between the electrode holes in the electrode hole group is less than the distance between two adjacent electrode hole groups.

7. The energy storage element according to claim 6, characterized in that, The distance between the two electrode hole groups in the first direction is set as the first distance, and the distance between the two electrode hole groups in a third direction orthogonal to the first direction and the second direction is set as the second distance, wherein the first distance is greater than the second distance.

8. The energy storage element according to claim 7, characterized in that, The first distance is more than 10 times the second distance.

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