Energy storage element

Abstract

To provide an energy storage element that allows electrolyte to easily permeate the electrode body. [Solution] The energy storage element 10 comprises an electrode body 700 in which electrode plates are stacked, and a container 100 in which the electrode body is housed. The electrode plates comprise a current collector foil and an active material layer, and also have electrode holes 731 which are through holes penetrating both the current collector foil and the active material layer. The container has an injection hole 131 for injecting electrolyte, and the electrode holes are positioned to overlap with the injection hole when viewed from the direction of penetration of the injection hole.

Description

Technical Field

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

Background Art

[0002] Patent Literature 1 discloses a secondary battery in which a positive electrode tab group and a negative electrode tab group of an electrode assembly are spaced apart from each other and bent to face a lid member, and an injection hole is arranged at a position sandwiched between regions where the positive electrode tab group and the negative electrode tab group are projected.

Prior Art Literature

Patent Literature

[0003]

Patent Literature 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] In the secondary battery disclosed in the above Patent Literature 1, it is described that the above configuration allows the electrolyte to be efficiently impregnated into the active material of the electrode assembly. However, in a secondary battery, depending on the size, shape, or other factors of the electrode assembly, it may be difficult for the electrolyte to permeate into the electrode assembly. Therefore, a configuration that allows the electrolyte to easily permeate into the electrode assembly is desired.

[0005] The present invention was made by the inventor of the present application newly focusing on the above problem, and an object of the present invention is to provide an electricity storage element that allows an electrolyte to easily permeate into an electrode body.

Means for Solving the Problem

[0006] An energy storage element according to one aspect of the present invention comprises an electrode body in which electrode plates are stacked, and a container in which the electrode body is housed, wherein the electrode plates comprise a current collector foil and an active material layer, and also have electrode holes which are through holes penetrating both the current collector foil and the active material layer, and the container has an injection hole for injecting an electrolyte, and the electrode holes are positioned to overlap with the injection hole when viewed from the direction of penetration of the injection hole. [Effects of the Invention]

[0007] According to the energy storage element of the present invention, the electrolyte can be easily permeated into the electrode body. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective view showing the external appearance of an energy storage element according to an embodiment. [Figure 2] Figure 2 is an exploded perspective view showing the individual components of the energy storage element according to the embodiment. [Figure 3] Figure 3 is a perspective view and a cross-sectional view showing the configuration of the electrode body according to the embodiment. [Figure 4] Figure 4 is a perspective view showing the configuration of the electrode body according to the embodiment, with the winding state of the electrode plate partially unfolded. [Figure 5] Figure 5 is a front view and a top view showing the configuration of electrode holes and electrode hole groups in an electrode body according to an embodiment. [Figure 6] Figure 6 is a top view and a cross-sectional view showing the configuration of electrode holes and electrode hole groups in an electrode body according to an embodiment. [Figure 7] Figure 7 is a cross-sectional view showing the positions where electrode holes and groups of electrode holes are formed in the electrode body according to the embodiment. [Figure 8] Figure 8 is a plan view showing an example of an energy storage device according to an embodiment. [Figure 9] Figure 9 is a cross-sectional view showing the positions where electrode holes and groups of electrode holes are formed in an electrode body according to a modified example 1 of the embodiment. [Modes for carrying out the invention]

[0009] (1) An energy storage element according to one aspect of the present invention comprises an electrode body in which electrode plates are stacked, and a container in which the electrode body is housed, wherein the electrode plate comprises a current collector foil and an active material layer, and also comprises an electrode hole which is a through hole that penetrates both the current collector foil and the active material layer, and the container comprises an injection hole for injecting an electrolyte, wherein the electrode hole is positioned to overlap with the injection hole when viewed from the direction of penetration of the injection hole.

[0010] According to one aspect of the present invention, the electrode plate of the electrode body is provided with electrode holes that penetrate both the current collector foil and the active material layer, and the electrode holes are positioned to overlap with the liquid injection holes when viewed from the direction of penetration of the liquid injection holes in the container. In this way, because the electrode plate of the electrode body is provided with electrode holes, the electrolyte can penetrate the electrode body through the electrode holes. Since the electrode holes penetrate both the current collector foil and the active material layer of the electrode plate, it is not necessary to provide a region on the current collector foil where the active material layer is not formed in order to form the electrode holes on the electrode plate, so the electrode holes can be easily formed on the electrode plate. Since the electrode holes are positioned to overlap with the liquid injection holes when viewed from the direction of penetration of the liquid injection holes, when the electrolyte is injected from the liquid injection holes, the electrolyte can easily reach the electrode holes. As a result, the electrolyte can easily penetrate the electrode body according to the present invention.

[0011] (2) In the energy storage element described in (1) above, the active material layer may be arranged around the electrode hole.

[0012] According to the energy storage element described in (2) above, by arranging the active material layer around the electrode holes in the electrode plate, the reduction in the area of ​​the active material layer can be suppressed even when electrode holes are formed in the electrode plate, thus suppressing the reduction in capacity.

[0013] (3) In the energy storage element described in (1) or (2) above, the electrode hole may be elongated in a predetermined direction when viewed from the through-direction.

[0014] According to the electricity storage element described in (3) above, since the electrode holes are elongated in a predetermined direction, the electrolytic solution can more easily permeate into the electrode body than in a case where the electrode holes are shorter. Since the electrode holes are elongated in the predetermined direction, positional displacement of the electrode holes in the predetermined direction can be suppressed.

[0015] (4) In the electricity storage element according to any one of (1) to (3) above, the electrode body is formed by winding the electrode plate, and the electrode hole is not formed in an inner peripheral portion closer to the innermost circumference than the outermost circumference of the electrode plate, and may be formed in an outer peripheral portion closer to the outermost circumference than the innermost circumference of the electrode plate.

[0016] According to the electricity storage element described in (4) above, the electrode hole is not formed in the inner peripheral portion closer to the innermost circumference than the outermost circumference of the wound electrode plate, but is formed in the outer peripheral portion closer to the outermost circumference than the innermost circumference of the electrode plate. When the electrode plate is wound, the electrolytic solution is less likely to permeate into the electrode body, but forming the electrode hole in the electrode plate allows the electrolytic solution to easily permeate into the electrode body even when the electrode plate is wound. Even if no electrode hole is formed in the inner peripheral portion of the electrode body, forming the electrode hole in the outer peripheral portion of the electrode body allows the electrolytic solution to permeate into the electrode body. By not forming an electrode hole in the inner peripheral portion of the electrode body, reduction in capacity caused by forming the electrode hole can be suppressed.

[0017] (5) In the electricity storage element according to any one of (1) to (4) above, the electrode hole is not formed at an end portion of the electrode body as viewed from the penetration direction, and may be formed in a central portion of the electrode body.

[0018] According to the electricity storage element described in (5) above, the electrode hole is not formed at an end portion of the electrode body, but is formed in a central portion of the electrode body. As described above, even if no electrode hole is formed at the end portion of the electrode body, forming the electrode hole in the central portion of the electrode body allows the electrolytic solution to permeate into the electrode body. By not forming an electrode hole at the end portion of the electrode body, reduction in capacity caused by forming the electrode hole can be suppressed.

[0019] (6) In the energy storage element described in any one of (1) to (5) above, the electrode hole may not penetrate in a direction perpendicular to the penetration direction, but penetrate in the penetration direction or in a direction intersecting the penetration direction.

[0020] According to the energy storage element described in (6) above, the electrode holes do not penetrate in a direction perpendicular to the direction of penetration of the liquid injection hole, but penetrate in the direction of penetration or in a direction intersecting the direction of penetration. In this way, because the electrode holes penetrate in the direction of penetration of the liquid injection hole or in a direction intersecting the direction of penetration, the electrolyte can easily pass through the electrode holes when the electrolyte is injected from the liquid injection hole. By not forming electrode holes that penetrate in a direction perpendicular to the direction of penetration of the liquid injection hole, the reduction in capacity due to the formation of electrode holes can be suppressed.

[0021] (7) In the energy storage element described in any one of (1) to (6) above, the electrode plate comprises a positive electrode plate and a negative electrode plate, and the positive electrode plate and the negative electrode plate each have a plurality of positive electrode holes and a plurality of negative electrode holes formed therein, and the plurality of positive electrode holes and the plurality of negative electrode holes are arranged to overlap when viewed from the through direction.

[0022] According to the energy storage element described in (7) above, the multiple positive electrode holes of the positive electrode plate and the multiple negative electrode holes of the negative electrode plate are positioned to overlap when viewed from the direction through which the electrolyte is injected. This allows the electrolyte to penetrate the electrode body more easily when injected through the electrolyte hole.

[0023] The following description of an energy storage element according to an embodiment (including its modifications) of the present invention will be given with reference to the drawings. The embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement and connection configurations of components, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples and are not intended to limit the present invention. Dimensions and other specifications are not strictly illustrated in each figure. In each figure, the same or similar components are denoted by the same reference numerals.

[0024] In the following description and drawings, the direction in which the pair of terminals (positive and negative, hereinafter the same) of the energy storage element are aligned, the direction in which the pair of current collectors are aligned, the winding axis direction of the electrode body, the direction in which the electrode body or container extends (the direction in which the width is longest), or the direction in which a pair of short sides of the container face each other is defined as the X-axis direction. The thickness direction of the electrode body or container (the direction in which the width is shortest), the direction in which a pair of long sides of the container face each other, or the direction in which a pair of flat parts of the electrode body face each other is defined as the Y-axis direction. The direction in which the container body and lid of the container are aligned, the direction in which the liquid injection hole of the container penetrates, the direction in which a pair of curved parts of the electrode body face each other, or the vertical direction is defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Depending on the usage, the Z-axis direction may not be the vertical direction, but for the sake of explanation below, the Z-axis direction will be described as the vertical direction.

[0025] In the following explanation, the X-axis positive direction refers to the direction of the X-axis arrow, and the X-axis negative direction refers to the opposite direction. When simply referred to as the X-axis direction, it refers to either the X-axis positive direction or the X-axis negative direction, or either direction. The same applies to the Y-axis and Z-axis directions. Expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where they are not strictly those directions or orientations. When two directions are parallel (or orthogonal), it means not only that the two directions are perfectly parallel (or orthogonal), but also that they are substantially parallel (or orthogonal), i.e., that they include a difference of, for example, a few percent. In the following explanation, when referred to as "insulation," it means "electrical insulation." The volume resistivity of an insulating material is 1 × 10⁻⁶ 6 Preferably, it is Ωm or higher, 1 × 10 7 Ωm or greater is more preferable, 1 × 10 10 A value of Ωm or higher is even more preferable.

[0026] (Embodiment) [1. General description of the energy storage element 10] First, a general description of the energy storage element 10 in this embodiment will be given using Figures 1 and 2. Figure 1 is a perspective view showing the external appearance of the energy storage element 10 according to this embodiment. Figure 2 is an exploded perspective view showing the individual components of the energy storage element 10 according to this embodiment.

[0027] The energy storage element 10 is a secondary battery (single cell) capable of charging and discharging electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 is used as a battery for driving or starting the engine of mobile vehicles such as automobiles, motorcycles, watercraft, ships, snowmobiles, agricultural machinery, construction machinery, automated guided vehicles (AGVs), aircraft, or railway vehicles for electric railways. Examples of automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicles. Examples of railway vehicles for electric railways include electric trains, monorails, maglev trains, and hybrid trains equipped with both diesel engines and electric motors. The energy storage element 10 can also be used as a stationary battery for household or commercial use.

[0028] The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery; it may be a secondary battery other than a non-aqueous electrolyte secondary battery, or a capacitor. The energy storage element 10 may be a primary battery instead of a secondary battery. The energy storage element 10 may be a pouch-type energy storage element. In this embodiment, the energy storage element 10 is shown as a rectangular parallelepiped (square) shape that is flattened in the Y-axis direction, but the shape of the energy storage element 10 is not limited to a rectangular parallelepiped; it may be a polygonal prism, an oblong cylinder, an elliptical cylinder, or a cylinder, etc.

[0029] As shown in Figure 1, the energy storage element 10 comprises a container 100, a pair of terminals 300 (positive and negative), and a pair of upper gaskets 400 (positive and negative). The energy storage element 10 further comprises a pair of lower gaskets 500 (positive and negative), a pair of current collectors 600 (positive and negative), and an electrode body 700, all of which are housed inside the container 100. In addition to the above components, spacers may be placed to the side or below the electrode body 700, an insulating film may be placed around the electrode body 700, etc.

[0030] The container 100 contains an electrolyte (non-aqueous electrolyte), but its 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; various types can be selected. The electrolyte contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous solvent 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), linear carbonates such as ethyl methyl carbonate (EMC), carboxylic acid esters, phosphate esters, sulfonic acid esters, ethers, amides, and nitriles. As the non-aqueous solvent, compounds in which some of the hydrogen atoms are substituted with halogens may also be used. The electrolyte salt can be appropriately selected from known electrolyte salts. Examples of electrolyte salts include lithium salts such as inorganic lithium salts like LiPF6, sodium salts, potassium salts, magnesium salts, and onium salts. Among these, lithium salts are preferred. The electrolyte may contain additives such as biphenyl in addition to a non-aqueous solvent and an electrolyte salt.

[0031] The container 100 is a case having an outer shape that is elongated and flattened in the X-axis direction, and is roughly rectangular. In this embodiment, the length of the container 100 in the X-axis direction is three times or more the length of the container 100 in the Z-axis direction. The container 100 is a rectangular (square or box) case comprising a container body 110 having an opening facing in the Z-axis positive direction and a lid 120 that closes the opening of the container body 110. The lid 120 is a flat and rectangular member that constitutes the lid portion of the container 100 and is positioned in the Z-axis positive direction of the container body 110. The lid 120 is a wall portion that extends in the X-axis direction.

[0032] The container body 110 is a rectangular cylindrical member with a bottom that constitutes the main body of the container 100. The container body 110 has a pair of long side walls 111 on both sides (sides) in the Y-axis direction, a pair of short side walls 112 on both sides (sides) in the X-axis direction, and a bottom wall 113 on the side (bottom) in the negative Z-axis direction. The long side walls 111 are flat and rectangular walls extending in the X-axis direction and include the long sides of the container 100. The long side walls 111 are adjacent to the short side walls 112, the bottom wall 113, and the lid 120, and have a larger area than the short side walls 112. The short side walls 112 are flat and rectangular walls extending in the Z-axis direction and include the short sides of the container 100. The short side wall portion 112 is adjacent to the long side wall portion 111, the bottom wall portion 113, and the lid 120, and has a smaller area than the long side wall portion 111. The bottom wall portion 113 is a flat, rectangular wall portion extending in the X-axis direction and includes the bottom surface of the container 100. The bottom wall portion 113 is positioned adjacent to the long side wall portion 111 and the short side wall portion 112.

[0033] The container 100 is sealed by welding or other means to the container body 110 and the lid 120 after the electrode body 700 and other components are housed inside the container body 110. The material of the container 100 (container body 110 and lid 120) is not particularly limited and can be made of weldable metals such as stainless steel, aluminum, aluminum alloy, iron, plated steel sheet, etc., and resin can also be used. The container body 110 and the lid 120 may 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 may be a laminate film composed of multiple layers including a metal layer and a resin layer.

[0034] The container 100 has a liquid injection section 130 and a gas discharge valve 140. In this embodiment, the liquid injection section 130 and the gas discharge valve 140 are formed in the lid 120. The gas discharge valve 140 is a safety valve that releases pressure when the pressure inside the container 100 rises excessively. In this embodiment, the gas discharge valve 140 is located in the center of the lid 120 in both the X-axis and Y-axis directions, but it may be located at any position on the lid 120. The gas discharge valve 140 may also be formed in the container body 110.

[0035] The liquid injection section 130 is a part for injecting electrolyte into the container 100 during the manufacturing of the energy storage element 10. The liquid injection section 130 is used during the manufacturing of the energy storage element 10 to evacuate the inside of the container 100, inject electrolyte into the container 100 to impregnate the electrode body 700 with electrolyte, and degas the inside of the electrode body 700. In this embodiment, the liquid injection section 130 is located near the negative X-axis direction and in the center of the Y-axis direction of the lid 120, but it may be located at any position on the lid 120. The liquid injection section 130 may also be formed in the container body 110.

[0036] The liquid injection section 130 includes a liquid injection hole 131 and a liquid injection plug 132. The liquid injection hole 131 is a through-hole formed in the lid 120 for injecting electrolyte into the container 100. In this embodiment, the liquid injection hole 131 has a circular shape when viewed from the Z-axis direction and is a cylindrical through-hole that penetrates the lid 120 in the Z-axis direction. In other words, the direction of penetration of the liquid injection hole 131 is the Z-axis direction. The liquid injection plug 132 is a member that closes the liquid injection hole 131. Specifically, the liquid injection plug 132 is a closing member (lid member) that is joined to the lid 120 to close the liquid injection hole 131 after the electrolyte is injected into the container 100 by evacuating the inside of the container 100 through the liquid injection hole 131 during the manufacturing of the energy storage element 10. Methods for joining the liquid injection plug 132 to the lid 120 can include laser welding as a fusion joint or riveting as a mechanical joint. The material of the liquid injection plug 132 is not particularly limited, but any metal or the like that can be used for the container 100 (lid 120) can be used. Preferably, the liquid injection plug 132 is made of the same material as the lid 120 or a material that can be welded to the lid 120.

[0037] Terminals 300 are electrode terminals (positive and negative terminals) that are electrically connected to the electrode body 700 via the current collector 600. Terminals 300 are metal members that lead the electricity stored in the electrode body 700 to the external space of the energy storage element 10 and introduce electricity into the internal space of the energy storage element 10 in order to store electricity in the electrode body 700. The positive terminal 300 is made of a conductive material such as aluminum or an aluminum alloy, similar to the positive electrode current collector foil 741 of the electrode body 700 described later, and the negative terminal 300 is made of a conductive material such as copper or a copper alloy, similar to the negative electrode current collector foil 751 of the electrode body 700 described later. The busbars that electrically connect the terminals 300 of multiple energy storage elements 10 are made of a conductive material such as aluminum or an aluminum alloy. To weld the busbar and the negative terminal 300, a conductive material such as aluminum or an aluminum alloy can be used for a portion of the negative terminal 300 that contacts the busbar. The terminal 300 is connected (joined) to the current collector 600 by crimping or welding, and is attached to the cover 120. The terminal 300 is positioned so as to protrude in the Z-axis positive direction from the outer surface (Z-axis positive direction surface) of the cover 120. In this embodiment, the terminal 300 is a welded terminal that is joined to an external conductive material such as a busbar by welding, but the terminal 300 may also be a bolted terminal that has a bolt portion with a male threaded portion that protrudes in the Z-axis positive direction and is joined to the conductive material by bolt connection.

[0038] The current collector 600 is a conductive current collector (positive electrode current collector and negative electrode current collector) that is arranged on both sides of the electrode body 700 in the X-axis direction and connected (joined) to the electrode body 700 and the terminal 300, thereby electrically connecting the electrode body 700 and the terminal 300. The current collector 600 is connected (joined) to the non-active material layer portion 720 of the electrode body 700, which will be described later, by welding or ultrasonic bonding, and as described above, it is connected (joined) to the terminal 300 by crimping or welding, and fixed to the cover body 120. The material of the current collector 600 is not particularly limited, but in this embodiment, the positive electrode current collector 600 is made of aluminum or an aluminum alloy, similar to the positive electrode current collector foil 741 of the electrode body 700, which will be described later, and the negative electrode current collector 600 is made of copper or a copper alloy, similar to the negative electrode current collector foil 751 of the electrode body 700, which will be described later.

[0039] The upper gasket 400 is a plate-shaped, rectangular gasket positioned between the lid 120 of the container 100 and the terminal 300, and is responsible for insulation and sealing between the lid 120 and the terminal 300. The lower gasket 500 is a plate-shaped, rectangular gasket positioned between the lid 120 and the current collector 600, and is responsible for insulating between the lid 120 and the current collector 600. The upper gasket 400 and lower gasket 500 are formed from insulating materials 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.

[0040] The electrode body 700 is an energy storage element (power generation element) capable of storing electricity, formed by stacking electrode plates and separators. In this embodiment, the electrode body 700 is formed by winding electrode plates and separators around a winding axis L extending in the X-axis direction. The electrode body 700 has an elongated shape extending in the X-axis direction and has an oval-shaped elongated cylinder when viewed from the X-axis direction. The electrode body 700 comprises an electrode body main body portion 710 and active material layer non-formed portions 720 protruding from the electrode body main body portion 710 on both sides in the X-axis direction, and as described above, the active material layer non-formed portions 720 are connected (joined) to the current collector 600. The electrode body main body portion 710 has an electrode hole group 730 formed therein, which includes a plurality of electrode holes 731, as will be described later. The configuration of such an electrode body 700 will be described in detail below.

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

[0042] [2.1 General Description of Electrode Body 700] As shown in Figures 3 and 4, the electrode body 700 comprises two electrode plates, a positive electrode plate 740 and a negative electrode plate 750, and two separators, separators 761 and 762, which are separators 760.

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

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

[0045] The separator 760 (761 and 762) is a microporous insulating sheet made of resin or the like. Any known material can be used for the separator 760, as long as it does not impair the performance of the energy storage element 10. Examples of separator 760 include woven fabric, nonwoven fabric, and porous resin film. Among these examples, porous resin film is preferred from the viewpoint of strength, and nonwoven fabric is preferred from the viewpoint of electrolyte retention. Polyolefins such as polyethylene and polypropylene are preferred as the material for the separator 760 from the viewpoint of shutdown function, and polyimide and aramid are preferred from the viewpoint of oxidative degradation resistance. A composite material of these resins may also be used for the separator 760. Separators 761 and 762 may be formed from the same material or from different materials.

[0046] The electrode body 700 is formed by alternately stacking and winding positive electrode plates 740 and negative electrode plates 750, and separators 761 and 762, as described above. In other words, the electrode body 700 is formed by stacking and winding 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 positive electrode plate 740 and negative electrode plate 750, etc., around a winding axis L extending in the X-axis direction. The winding axis L is a virtual axis that serves as the central axis when winding positive electrode plate 740 and negative electrode plate 750, etc., and in this embodiment, it is a straight line parallel to the X-axis direction that passes through the center of the electrode body 700.

[0047] Specifically, the electrode body 700 has a positive electrode plate 740 and a negative electrode plate 750 wound around each other via separators 761 and 762, offset from each other in the direction along the winding axis L (also called the winding axis direction, in this embodiment, the X-axis direction). The positive electrode plate 740 and the negative electrode plate 750 have active material layer non-formed portions 720 at their respective offset ends where the positive electrode active material layer 742 and the negative electrode active material layer 752 are not formed (coated), and the positive electrode current collector foil 741 and the negative electrode current collector foil 751 are exposed. In other words, the electrode body 700 has a positive electrode active material layer non-formed portion 720 at one end in the winding axis direction, where the ends of the positive electrode current collector foil 741 are stacked and bundled, and a negative electrode active material layer non-formed portion 720 at the other end in the winding axis direction, where the ends of the negative electrode current collector foil 751 are stacked and bundled.

[0048] Thus, the electrode body 700 comprises an electrode body main body portion 710 that constitutes the main body of the electrode body 700, and a pair of non-active material layer portions 720 (positive electrode and negative electrode) that protrude from the electrode body main body portion 710 on both sides in the X-axis direction. The electrode body main body portion 710 is an elongated cylindrical portion formed by winding the active material layer forming portion 713 of the electrode plates (positive electrode plate 740 and negative electrode plate 750) and the separator 760. The active material layer forming portion 713 is the portion of the electrode plate in which the active material layer is formed in a direction perpendicular to the X-axis direction of the current collector foil. In Figure 3(b), the active material layer forming portion 713 is the portion of the positive electrode plate 740 in which the positive electrode active material layer 742 is coated in the Z-axis direction of the positive electrode current collector foil 741, and the portion of the negative electrode plate 750 in which the negative electrode active material layer 752 is coated in the Z-axis direction of the negative electrode current collector foil 751. As a result, as shown in Figure 3(a), 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. 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 axis L.

[0049] The curved portion 711 is a curved part that extends in the X-axis direction, curved in the shape of a semicircular arc so as to project in the Z-axis direction when viewed from the X-axis direction, and is positioned opposite the bottom wall portion 113 and the lid portion 120 of the container body 110. In other words, the pair of curved portions 711 are curved parts that project in the Z-axis direction toward the bottom wall portion 113 and the lid portion 120 of the container body 110 when viewed from the X-axis direction. The flat portion 712 is a rectangular and flat part that extends along the XZ plane oriented in the Y-axis direction, connecting the ends of the pair of curved portions 711, and is positioned opposite the long side walls 111 on both sides of the container body 110 in the Y-axis direction. The curved shape of the curved portion 711 is not limited to a semicircular arc shape, but may be part of an ellipse, or any other shape. The flat portion 712 is not limited to having a flat outer surface facing the Y-axis direction, but may have a slightly concave or slightly bulging outer surface.

[0050] With the above configuration, the electrode body 700 has a long (horizontally elongated) shape with a long length in the winding axis direction (X-axis direction). In other words, the length of the electrode body 700 in the X-axis direction is longer than the length of the electrode body 700 in the Y-axis direction and the Z-axis direction. In this embodiment, the electrode body 700 preferably has a length of 300 mm or more in the X-axis direction, more preferably 600 mm or more, and even more preferably 900 mm or more, but it may be shorter than 300 mm. In this embodiment, the electrode body 700 has a length of 1500 mm or less in the X-axis direction, but it may be longer than 1500 mm. The length of the electrode body 700 in the X-axis direction may be three times or more the length of the electrode body 700 in the Z-axis direction.

[0051] The electrode body 700 is a wound type (so-called vertical winding type) electrode body in which the winding axis L extends in the X-axis direction, the curved portion 711 in the Z-axis negative direction faces the bottom wall portion 113 of the container body 110, and the curved portion 711 in the Z-axis positive direction faces the lid portion 120 of the container body 110. At one and the other end in the X-axis direction of the non-active material layer portion 720 of the wound electrode body 700, the cross-sections of the stacked positive electrode plate 740 or negative electrode plate 750 layers are exposed in the X-axis direction, so the electrolyte can easily seep between the layers of the positive electrode plate 740 and the negative electrode plate 750 from the X-axis direction.

[0052] Furthermore, as shown in Figure 4, multiple electrode holes 731 are formed in the active material layer forming portion 713 of the electrode body main portion 710 of the electrode body 700. In Figures 2 and 3, the electrode holes 731 are hidden by the separator 760 and are therefore not shown, but in Figure 4, the electrode holes 731 hidden by the separator 760 are also shown. Figure 4 is an illustrative diagram showing the arrangement and shape of the electrode holes 731, and may differ from the actual size of the electrode holes 731. The same applies to Figure 5 and others described later. In this embodiment, these multiple electrode holes 731 are arranged in the stacking direction of the electrode plates (positive electrode plate 740 and negative electrode plate 750), thereby forming an electrode hole group 730 consisting of these multiple electrode holes 731. The configuration of the electrode holes 731 and the electrode hole group 730 will be described in detail below, with reference to Figures 5 to 7.

[0053] [2.2 Description of electrode holes 731 and electrode hole group 730] Figure 5 is a front view and a top view showing the configuration of the electrode holes 731 and electrode hole group 730 of the electrode body 700 according to this embodiment. Figure 5(a) is a front view showing the configuration of the energy storage element 10 when viewed from the negative Y-axis direction, with the electrode body 700 inside the container 100 shown by a dashed line. Figure 5(b) is an enlarged top view showing the configuration of the liquid injection section 130 (injection hole 131) of the container 100 when viewed from the positive Z-axis direction, with the components appropriately transparently viewed, and the configuration of the liquid injection hole 131 and electrode holes 731 (electrode hole group 730) shown by solid lines. Figure 6 is a top view and a cross-sectional view showing the configuration of the electrode holes 731 and electrode hole group 730 of the electrode body 700 according to this embodiment. Figure 6(a) is a top view showing the configuration of the electrode holes 731 and electrode hole groups 730 when viewed from the Z-axis positive direction, and Figure 6(b) is a cross-sectional view showing the VIb-VIb section in Figure 6(a). Other electrode holes 731 not shown in Figure 6 have the same configuration as the electrode holes 731 shown in Figure 6. Figure 7 is a cross-sectional view showing the positions where the electrode holes 731 and electrode hole groups 730 are formed in the electrode body 700 according to this embodiment. Figure 7 is a cross-sectional view showing the VII-VII section in Figure 5, showing a cross-section when the energy storage element 10 is cut at the positions of the electrode holes 731 and electrode hole groups 730. In Figure 7, the positions where the electrode holes 731 and electrode hole groups 730 are formed are shown by dashed lines.

[0054] As described above, the electrode plates of the electrode body 700 are provided with an active material layer forming section 713 in which an active material layer is formed in a direction perpendicular to the X-axis direction of the current collector foil (the Z-axis direction in Figure 6). Specifically, the positive electrode plate 740 is provided with a positive electrode active material layer forming section 713 in which a positive electrode active material layer 742 is formed in a direction perpendicular to the X-axis direction of the positive electrode current collector foil 741 (the Z-axis direction in Figure 6). The negative electrode plate 750 is provided with a negative electrode active material layer forming section 713 in which a negative electrode active material layer 752 is formed in a direction perpendicular to the X-axis direction of the negative electrode current collector foil 751 (the Z-axis direction in Figure 6). In other words, the positive electrode current collector foil 741 and the positive electrode active material layer 742, excluding the positive electrode active material layer non-forming section 720 of the positive electrode plate 740, are referred to as the positive electrode active material layer forming section 713. The negative electrode current collector foil 751 and the negative electrode active material layer 752, excluding the portion 720 of the negative electrode plate 750 where the negative electrode active material layer is not formed, are referred to as the negative electrode active material layer forming portion 713. In other words, the portion of the positive electrode plate 740 other than the portion 720 where the positive electrode active material layer is not formed is referred to as the positive electrode active material layer forming portion 713, and the portion of the negative electrode plate 750 other than the portion 720 where the negative electrode active material layer is not formed is also referred to as the negative electrode active material layer forming portion 713.

[0055] In this embodiment, since the electrode plates (positive electrode plate 740 and negative electrode plate 750) are wound, the active material layer forming section 713 is also wound. As a result, as shown in Figure 6, the active material layer forming section 713 constitutes multiple layers 713a in the Z-axis direction. In other words, the active material layer forming section 713 comprises multiple layers 713a stacked in the Z-axis direction. Specifically, in the positive electrode plate 740, three layers, each consisting of two positive electrode active material layers 742 formed on both sides of a positive electrode current collector foil 741 (one layer) in the Z-axis direction, are considered as one unit and are referred to as one layer 713a (positive electrode layer 713a). In the negative electrode plate 750, three layers, each consisting of two negative electrode active material layers 752 formed on both sides of a negative electrode current collector foil 751 (one layer) in the Z-axis direction, are considered as one unit and are 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, a plurality of positive electrode layers 713a and a plurality of negative electrode layers 713a are stacked with separators 761 or 762 placed between the positive electrode layer 713a and the negative electrode layer 713a. The electrode body portion 710 is formed by stacking these plurality of positive electrode layers 713a, plurality of negative electrode layers 713a, and separators 761 and 762.

[0056] At least one of the multiple layers 713a of the electrode plates (positive electrode plate 740 and negative electrode plate 750) is provided with an electrode hole 731, which is a through-hole that penetrates both the current collector foil and the active material layer. In this embodiment, each of two or more consecutive layers 713a is provided with an electrode hole 731. Figure 6 shows four consecutive layers 713a, that is, two positive electrode layers 713a and two negative electrode layers 713a. Each of the two positive electrode layers 713a is provided with a positive electrode hole 740a, which is a positive electrode hole 731 that penetrates both the positive electrode current collector foil 741 and the positive electrode active material layer 742. The positive electrode hole 740a is a through-hole that penetrates the positive electrode current collector foil 741 and the positive electrode active material layer 742 provided on both sides of the positive electrode current collector foil 741 in the Z-axis direction. Each of the two negative electrode layers 713a has a negative electrode hole 750a, which is a negative electrode hole 731 that penetrates both the negative electrode current collector foil 751 and the negative electrode active material layer 752. The negative electrode hole 750a is a through-hole that penetrates the negative electrode current collector foil 751 and the negative electrode active material layer 752 provided on both sides of the negative electrode current collector foil 751 in the Z-axis direction.

[0057] In this embodiment, electrode holes 731 are provided in all layers 713a of the positive electrode plate 740 and the negative electrode plate 750. Specifically, positive electrode holes 740a are provided in all layers 713a of the active material layer forming portion 713 of the positive electrode plate 740, and negative electrode holes 750a are provided in all layers 713a of the active material layer forming portion 713 of the negative electrode plate 750. These multiple electrode holes 731 (multiple positive electrode holes 740a and multiple negative electrode holes 750a) are referred to as the electrode hole group 730. In this embodiment, as shown in Figure 4, the electrode hole group 730 comprises multiple electrode holes 731 arranged in the winding direction of the electrode plate (the Z-axis direction in Figure 4) when the winding state of the electrode plate is unfolded. In other words, the electrode hole group 730 comprises a plurality of positive electrode holes 740a arranged in the winding direction on the positive electrode plate 740, and a plurality of negative electrode holes 750a arranged in the winding direction on the negative electrode plate 750.

[0058] As shown in Figure 5, the electrode holes 731 (electrode hole group 730) are positioned directly below the liquid injection section 130 (liquid injection hole 131). Specifically, the electrode holes 731 are positioned so as to overlap with the liquid injection hole 131 when viewed from the direction of penetration of the liquid injection hole 131 (Z-axis direction). In this embodiment, the electrode hole group 730, which comprises multiple electrode holes 731, is positioned so as to overlap with the liquid injection hole 131 when viewed from the direction of penetration of the liquid injection section (Z-axis direction). When viewed from the direction of penetration of the liquid injection section (Z-axis direction), the electrode holes 731 (electrode hole group 730) are positioned so as to overlap with the liquid injection hole 131.

[0059] As shown in Figure 6, the multiple electrode holes 731 in the electrode hole group 730 are arranged in overlapping positions when viewed from the direction of penetration (Z-axis direction) of the liquid injection hole 131. Specifically, the multiple positive electrode holes 740a and the multiple negative electrode holes 750a are arranged in overlapping positions when viewed from the direction of penetration (Z-axis direction) of the liquid injection hole 131. In this embodiment, all positive electrode holes 740a and all negative electrode holes 750a are arranged in overlapping positions when viewed from the direction of penetration (Z-axis direction).

[0060] Specifically, the positive electrode hole 740a in the positive electrode layer 713a and the negative electrode hole 750a in the negative electrode layer 713a, which are adjacent to each other with the separator 761 in the Z-axis direction, are positioned to overlap when viewed from the Z-axis direction. In this embodiment, the positive electrode hole 740a and the negative electrode hole 750a are positioned at the same location when viewed from the Z-axis direction, but as long as they are positioned to overlap when viewed from the Z-axis direction, they may be positioned slightly offset in one or both of the X-axis and Y-axis directions. The same applies to the positive electrode hole 740a in the positive electrode layer 713a and the negative electrode hole 750a in the negative electrode layer 713a, which are adjacent to each other with the separator 762 in between. The same applies to positive electrode holes 740a in different positive electrode layers 713a, and the same applies to negative electrode holes 750a in different negative electrode layers 713a. In other words, the multiple electrode holes 731 provided in different layers 713a are positioned to overlap when viewed from the Z-axis direction.

[0061] The separator 760, positioned between the adjacent positive electrode plate 740 and negative electrode plate 750, has microporosity, allowing for easy penetration of the electrolyte and exhaust of gases within the separator 760. Therefore, through holes do not need to be formed in the separator 760. If microporosity is considered as through holes, then it can be said that through holes are also provided in the separator 760. For this reason, in this embodiment, through holes such as the electrode holes 731 are not formed in the separator 760, but through holes such as the electrode holes 731 may be formed in the separator 760 (either one or both of the separators 761 and 762). When such through holes are formed in the separator 760, they may be positioned at the same location as the electrode holes 731 when viewed from the Z-axis direction, or at a shifted position, but it is preferable to position them in a position that overlaps with the electrode holes 731 in order to improve the penetration of the electrolyte.

[0062] The electrode hole 731 is elongated in a predetermined direction when viewed from the through-direction (Z-axis direction) of the injection hole 131. In this embodiment, the electrode hole 731 is a linear (straight) hole extending in the winding direction of the electrode plate (Y-axis direction in Figures 5 and 6), and is elongated in the winding direction (Y-axis direction) of the electrode plate. As shown in Figure 5, the length of the electrode hole 731 in the X-axis direction (short direction) is referred to as length A, and the length of the electrode hole 731 in the Y-axis direction (long direction) is referred to as length B. Lengths A and B are the lengths of the electrode hole 731 when the electrode plate is unfolded and flattened. If the length of the electrode hole 731 in the X-axis direction is not constant, the maximum length of the electrode hole 731 in the X-axis direction is referred to as length A. If the length of the electrode hole 731 in the Y-axis direction is not constant, the maximum length of the electrode hole 731 in the Y-axis direction is referred to as length B.

[0063] The length A of the electrode hole 731 in the short direction (X-axis direction) is 300 μm or less. A shorter length A is preferable because it suppresses the reduction in the area of ​​the active material layer and reduces and minimizes the amount of contamination generated. For this reason, the length A is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. If the length A is too short, the electrolyte will have difficulty passing through the electrode hole 731, and the permeability of the electrolyte will decrease. Furthermore, if the length A is too short, it will be difficult to process the electrode hole 731, requiring the use of a high-power density and low-power laser, and a large number of laser irradiations. For this reason, the length A is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. In other words, the length A is preferably 10 μm or more and 200 μm or less, more preferably 20 μm or more and 150 μm or less, and even more preferably 30 μm or more and 100 μm or less.

[0064] In the longitudinal direction (Y-axis direction) of the electrode hole 731, a longer length B is preferable because it allows for a larger opening area of ​​the electrode hole 731. Preferably, length B is 1.3 times or more the length A, more preferably 1.5 times or more the length A, and even more preferably 3 times or more the length A. If length B is too long, the area of ​​the active material layer decreases, leading to a decrease in capacity (power density), which is undesirable. Therefore, preferably, length B is 30 times or less the length A, more preferably 10 times or less the length A, and even more preferably 5 times or less the length A. In other words, preferably, length B is 1.3 times or more and 30 times or less the length A, more preferably 1.5 times or more and 10 times or less the length A, and even more preferably 3 times or more and 5 times or less the length A.

[0065] Specifically, the length B in the longitudinal direction (Y-axis direction) of the electrode hole 731 is preferably 20 μm or more, more preferably 40 μm or more, and even more preferably 60 μm or more. The length B is preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 300 μm or less. In other words, the length B is preferably 20 μm or more and 1000 μm or less, more preferably 40 μm or more and 500 μm or less, and even more preferably 60 μm or more and 300 μm or less.

[0066] In this embodiment, all electrode holes 731 (positive electrode hole 740a and negative electrode hole 750a) have the same shape and size, but any one of the electrode holes 731 may have a different shape or size. The edges of the electrode holes 731 in the longitudinal direction (Y-axis direction) are curved (semicircular), but they may be semi-elliptical, other curved shapes, or polygonal shapes such as rectangles.

[0067] As shown in Figure 5, the electrode holes 731 (electrode hole group 730) are formed in the central part of the electrode body 700, but not at the ends of the electrode body 700 when viewed from the direction of penetration of the injection hole 131 (Z-axis direction). In this embodiment, the ends of the electrode body 700 are the ends in the positive X-axis direction and the ends in the negative X-axis direction when the electrode body 700 is divided into three equal parts in the X-axis direction. The central part of the electrode body 700 is the central part in the X-axis direction when the electrode body 700 is divided into three equal parts in the X-axis direction. In other words, the electrode holes 731 (electrode hole group 730) are formed in the central part in the X-axis direction, but not at both ends in the X-axis direction when the electrode body 700 is divided into three equal parts in the X-axis direction. The electrode holes 731 (electrode hole group 730) may also be formed in the central part in the X-axis direction (a part located near the center) when the electrode body 700 is divided into four or more equal parts in the X-axis direction, but not at both ends in the X-axis direction (the parts located at the very ends).

[0068] As shown in Figure 7, the electrode holes 731 (electrode hole group 730) are formed in the curved portion 711 of the electrode body 700. Specifically, the electrode holes 731 (electrode hole group 730) are formed in a pair of curved portions 711 on both sides of the electrode body 700 in the Z-axis direction, at positions that overlap with the injection hole 131 when viewed from the Z-axis direction. The electrode holes 731 formed in the curved portion 711 in the Z-minus direction are positioned opposite to the electrode holes 731 formed in the curved portion 711 in the Z-plus direction in the Z-axis direction. The electrode hole group 730 is a collection of electrode holes 731 that are formed in each layer 713a of the active material layer forming portion 713 in the curved portion 711 and are arranged linearly in the Z-axis direction. In each curved portion 711, the electrode holes 731 are continuously formed from the layer 713a at one end in the Z-axis direction (the outermost layer 713a) to the layer 713a at the other end in the Z-axis direction (the innermost layer 713a).

[0069] The electrode holes 731 penetrate each layer 713a of the active material layer forming portion 713 in the curved portion 711 of the electrode body 700 in the Z-axis direction. The electrode holes 731 may also penetrate each layer 713a of the curved portion 711 in a direction inclined from the Z-axis direction (a direction intersecting the Z-axis direction). However, since the electrode holes 731 are not formed in the flat portion 712 of the electrode body 700, they do not penetrate the electrode body 700 in the Y-axis direction. Thus, the electrode holes 731 do not penetrate in a direction perpendicular to the penetration direction (Z-axis direction) of the injection hole 131 (Y-axis direction), but penetrate in the said penetration direction (Z-axis direction) or in a direction intersecting the said penetration direction (a direction inclined from the Z-axis direction).

[0070] In this embodiment, a laser beam is irradiated onto the current collector foil of the electrode plate at the location where the active material layer is formed to form electrode holes 731. This creates electrode holes 731 that penetrate both the current collector foil and the active material layer, and the active material layer is arranged around the electrode holes 731. That is, the positive electrode active material layer 742 is arranged around the positive electrode hole 740a, and the negative electrode active material layer 752 is arranged around the negative electrode hole 750a. In this embodiment, the laser beam is irradiated just before winding the electrode plate to form the electrode holes 731. This allows the spacing (pitch) between the electrode holes 731 to be adjusted, so that the electrode holes 731 can be formed in a more precise location. Specifically, the pitch for forming the electrode holes 731 is shortened closer to the innermost circumference of the electrode body 700, and the pitch for forming the electrode holes 731 is lengthened closer to the outermost circumference of the electrode body 700. When forming the electrode holes 731, the laser beam is irradiated from the same direction on the electrode plate. This allows the direction in which the burrs (debris) formed around the electrode hole 731 protrude to be aligned, thereby suppressing damage to the separator 760 when the electrode plate is wound.

[0071] [3. Explanation of the effect] As described above, according to the embodiment of the present invention, the electrode plates (positive electrode plate 740, negative electrode plate 750) of the electrode body 700 are provided with electrode holes 731 that penetrate both the current collector foil (positive electrode current collector foil 741, negative electrode current collector foil 751) and the active material layer (positive electrode active material layer 742, negative electrode active material layer 752). The electrode holes 731 are positioned to overlap with the liquid injection hole 131 when viewed from the penetrating direction (Z-axis direction) of the liquid injection hole 131 of the container 100. In this way, because the electrode plates of the electrode body 700 are provided with electrode holes 731, the electrolyte can penetrate the electrode body 700 through the electrode holes 731. Since the electrode holes 731 penetrate both the current collector foil and the active material layer of the electrode plate, it is not necessary to provide a region on the current collector foil where the active material layer is not formed in order to form the electrode holes 731 on the electrode plate, and therefore the electrode holes 731 can be easily formed on the electrode plate. The electrode hole 731 is positioned so as to overlap with the injection hole 131 when viewed from the direction of penetration (Z-axis direction) of the injection hole 131. This allows the electrolyte to easily reach the electrode hole 731 when injected from the injection hole 131. As a result, the energy storage element 10 allows the electrolyte to easily penetrate the electrode body 700.

[0072] In particular, by injecting the electrolyte through the injection hole 131, the electrolyte can be supplied directly to the electrode hole 731 while avoiding the bubbles (foaming) generated during injection. This allows the electrolyte to easily penetrate the electrode body 700 and be easily supplied to the electrode body 700. As a result, the time required for injection can be shortened.

[0073] In the electrode plates (positive electrode plate 740, negative electrode plate 750), by arranging the active material layer (positive electrode active material layer 742, negative electrode active material layer 752) around the electrode hole 731, the reduction in the area of ​​the active material layer can be suppressed even when the electrode hole 731 is formed in the electrode plate, thus suppressing the reduction in capacity.

[0074] When viewed from the direction of penetration of the electrode hole 731, if the electrode hole 731 is long in a predetermined direction (Y-axis direction or Z-axis direction), it is easier to penetrate the electrolyte into the electrode body 700 than if the electrode hole 731 were shorter. In an electrode body 700 wound around a winding axis L extending in the X-axis direction, if the electrode hole 731 is long in a predetermined direction intersecting the X-axis direction, it is possible to suppress misalignment of the electrode hole 731 in that predetermined direction, which may occur when winding the electrode plate, etc.

[0075] When the electrode plates (positive electrode plate 740, negative electrode plate 750) are wound, the electrolyte does not easily penetrate the electrode body 700. However, by forming electrode holes 731 in the electrode plates, the electrolyte can easily penetrate the electrode body 700 even when the electrode plates are wound.

[0076] The electrode holes 731 are formed in the central part of the electrode body 700, but not at the ends of the electrode body 700 when viewed from the direction of penetration of the injection hole 131 (Z-axis direction). In this way, even if the electrode holes 731 are not formed at the ends of the electrode body 700, the electrolyte can be permeated into the electrode body 700 by forming the electrode holes 731 in the central part of the electrode body 700. In particular, since the electrode body 700 is a wound-type electrode body with a winding axis L extending in the X-axis direction, the electrolyte can easily penetrate to the ends in the X-axis direction, but not so easily to the central part in the X-axis direction. For this reason, forming the electrode holes 731 in the central part of the electrode body 700 in the X-axis direction allows the electrolyte to easily penetrate into the electrode body 700. By not forming the electrode holes 731 at the ends of the electrode body 700 where the electrolyte can easily penetrate, the reduction in capacity due to the formation of the electrode holes 731 can be suppressed compared to forming electrode holes 731 at both the central part and the ends of the electrode body 700.

[0077] The electrode holes 731 do not penetrate in a direction perpendicular to the penetration direction (Z-axis direction) of the injection hole 131, but penetrate in the same direction or in a direction intersecting the said penetration direction. In this way, the electrode holes 731 penetrate in the same direction as the injection hole 131 or in a direction intersecting the said penetration direction, so that when the electrolyte is injected from the injection hole 131, the electrolyte can easily pass through the electrode holes 731. By not forming electrode holes 731 that penetrate in a direction perpendicular to the penetration direction (Z-axis direction) of the injection hole 131, the reduction in capacity due to the formation of electrode holes 731 can be suppressed.

[0078] By forming the electrode hole 731 in the electrode body 700 at a position close to the injection hole 131 (on the curved portion 711 in the positive Z-axis direction), the electrolyte can be directly permeated into the electrode body 700 from the electrode hole 731. By forming the electrode hole 731 at a position far from the injection hole 131 (on the curved portion 711 in the negative Z-axis direction), the electrolyte accumulated in the container 100 can be indirectly permeated into the electrode body 700 from the electrode hole 731. In this embodiment, the electrode hole 731 formed on the curved portion 711 in the negative Z-axis direction is positioned opposite to the electrode hole 731 formed on the curved portion 711 in the positive Z-axis direction in the Z-axis direction, so the electrode hole 731 can be easily formed when processing the electrode hole 731 with laser irradiation.

[0079] Multiple positive electrode holes 740a in the positive electrode plate 740 and multiple negative electrode holes 750a in the negative electrode plate 750 are positioned to overlap when viewed from the direction of penetration (Z-axis direction) of the liquid injection hole 131. This allows the electrolyte to penetrate the electrode body 700 more easily when injected through the liquid injection hole 131.

[0080] The electrode body 700 has a long shape that extends in the X-axis direction, making it difficult for the electrolyte to easily penetrate the electrode body 700 in the central part in the X-axis direction. However, with the above configuration, the electrolyte can easily penetrate the electrode body 700. In this embodiment, as described above, the electrode body 700 is a wound type electrode body with a winding axis L extending in the X-axis direction, and since the electrolyte does not easily penetrate the central part in the X-axis direction, the above configuration is highly effective. The electrode body 700 may be a stacked type electrode body formed by stacking multiple long, flat electrode plates that extend in the X-axis direction, or a bellows type electrode body formed by folding long electrode plates that extend in the X-axis direction in a bellows shape. Even in this case, the electrode body 700 has a long shape that extends in the X-axis direction, and since the electrolyte does not easily penetrate the central part in the X-axis direction, the above configuration is highly effective.

[0081] The energy storage element 10 may be used in an energy storage device. In this case, the technology of the present invention only needs to be applied to at least one energy storage element 10 provided in the energy storage device. Figure 8 is a plan view showing an example of an energy storage device 30 according to this embodiment. As shown in Figure 8, a plurality of energy storage units 20 are arranged inside the energy storage device 30. Each energy storage unit 20 is composed of a plurality of electrically connected energy storage elements 10. The energy storage device 30 may include busbars (not shown) that electrically connect the plurality of energy storage elements 10, busbars (not shown) that electrically connect the plurality of energy storage units 20, etc. The energy storage unit 20 or the energy storage device 30 may include a state monitoring device (not shown) that monitors the state of one or more energy storage elements 10. The energy storage device 30 may have only one energy storage unit 20 (that is, the energy storage unit 20 may be referred to as the energy storage device).

[0082] [4. Explanation of variations] Although an embodiment of the energy storage element 10 according to the present invention has been described above, the present invention is not limited to the above-described embodiment. The embodiments disclosed herein are illustrative in all respects, and the scope of the present invention includes all modifications in the sense and scope equivalent to the claims.

[0083] (Variation 1) In the above embodiment, electrode holes 731 are formed continuously from the outermost layer 713a to the innermost layer 713a in the active material layer forming portion 713 of the electrode plate of the electrode body 700, but this is not limited to this. There may be layers 713a between the outermost layer 713a and the innermost layer 713a in which electrode holes 731 are not formed. An example of this is described below. Figure 9 is a cross-sectional view showing the positions in which electrode holes 731 and electrode hole groups 730a are formed in the electrode body 700a according to Modification 1 of this embodiment. Figure 9 corresponds to Figure 7 and shows a cross-section when the energy storage element 11 is cut at the positions of the electrode holes 731 and electrode hole groups 730a, with the positions in which the electrode holes 731 and electrode hole groups 730a are formed indicated by dashed lines.

[0084] As shown in Figure 9, the energy storage element 11 in this modified example is equipped with an electrode body 700a instead of the electrode body 700 provided in the energy storage element 10 in the above embodiment. In this modified example, the electrode body 700a is equipped with electrode holes 731 and electrode hole group 730a instead of the electrode holes 731 and electrode hole group 730 formed in the electrode body 700 in the above embodiment.

[0085] Electrode holes 731 (electrode hole group 730a) are formed in a pair of curved portions 711 on both sides of the electrode body 700a in the Z-axis direction, at positions that overlap with the injection hole 131 when viewed from the Z-axis direction. The electrode hole group 730a is a collection of electrode holes 731 that are formed in each layer 713a of the active material layer forming portion 713 in the curved portion 711 and are arranged linearly in the Z-axis direction. In each curved portion 711, electrode holes 731 are continuously formed from the outermost layer 713a of the electrode plate to the layer 713a that is more outer than the innermost circumference of the electrode plate.

[0086] Here, in each curved portion 711, the part closer to the innermost circumference than the outermost circumference of the electrode plate is referred to as the inner circumference portion 711a, and the part closer to the outermost circumference than the innermost circumference of the electrode plate is referred to as the outer circumference portion 711b. In this modified example, when the layer 713a of the active material layer forming portion 713 in each curved portion 711 is divided into three equal parts in the Z-axis direction, the part including the innermost layer 713a is referred to as the inner circumference portion 711a, and the part including the outermost layer 713a is referred to as the outer circumference portion 711b. In this configuration, the electrode holes 731 are not formed in the inner circumference portion 711a, which is closer to the innermost circumference than the outermost circumference of the electrode plate, but are formed in the outer circumference portion 711b, which is closer to the outermost circumference than the innermost circumference of the electrode plate. In this modified example, the electrode holes 731 are also formed in the layer 713a between the inner circumference portion 711a and the outer circumference portion 711b. In other words, the electrode hole group 730a comprises electrode holes 731 that are formed in the layers 713a of the electrode plate, excluding the innermost layer 711a, from the outermost layer 713a to the innermost layer 713a, and are arranged linearly in the Z-axis direction.

[0087] In this modified example, when the layer 713a of each curved portion 711 is divided into two or four or more equal parts in the Z-axis direction, the portion including the innermost layer 713a may be designated as the inner circumference portion 711a, and the portion including the outermost layer 713a may be designated as the outer circumference portion 711b. The inner circumference portion 711a and the outer circumference portion 711b may contain any number of layers 713a. The electrode hole 731 does not need to be formed in the layer 713a between the inner circumference portion 711a and the outer circumference portion 711b. The inner circumference portion 711a may be a portion closer to the innermost circumference than the outermost circumference of the electrode plate, and does not need to include the innermost layer 713a. The outer circumference portion 711b may be a portion closer to the outermost circumference than the innermost circumference of the electrode plate, and does not need to include the outermost layer 713a. The other configurations of this modified example are the same as in the above embodiment, so a detailed explanation is omitted.

[0088] This modified version can achieve the same effects as the above embodiment. In particular, the electrode holes 731 are not formed in the inner circumference portion 711a, which is closer to the innermost circumference than the outermost circumference of the wound electrode plate, but rather in the outer circumference portion 711b, which is closer to the outermost circumference than the innermost circumference of the electrode plate. When the electrode plate is wound, the electrolyte does not easily penetrate into the electrode body 700a, but by forming electrode holes 731 in the electrode plate, the electrolyte can easily penetrate into the electrode body 700a even when the electrode plate is wound. Even if electrode holes 731 are not formed in the inner circumference portion 711a of the electrode body 700a, the electrolyte can penetrate into the electrode body 700a by forming electrode holes 731 in the outer circumference portion 711b of the electrode body 700a. By not forming electrode holes 731 in the inner circumference portion 711a of the electrode body 700a, the reduction in capacity due to the formation of electrode holes 731 can be suppressed.

[0089] (Other variations) In the above embodiment, all of the electrode holes 731 (electrode hole group 730) are positioned to overlap with the injection hole 131 when viewed from the through direction (Z-axis direction) of the injection hole 131, but this is not limited to this. In all of the electrode holes 731, it is preferable that at least a portion of the electrode hole 731 overlaps with the injection hole 131 when viewed from the Z-axis direction, but there may be electrode holes 731 that do not overlap with the injection hole 131 at all when viewed from the Z-axis direction.

[0090] In the above embodiment, all positive electrode holes 740a and all negative electrode holes 750a (all electrode holes 731) are positioned to overlap when viewed from the through direction (Z-axis direction) of the injection hole 131, but this is not limited to this. In all electrode holes 731, it is preferable that at least a part of one electrode hole 731 overlaps with any of the other electrode holes 731 when viewed from the Z-axis direction, but there may be electrode holes 731 that do not overlap with any of the other electrode holes 731 when viewed from the Z-axis direction.

[0091] In the above embodiment, electrode holes 731 are formed in a pair of curved portions 711 on both sides of the electrode body 700 in the Z-axis direction, at positions that overlap with the injection hole 131 when viewed from the Z-axis direction, but the embodiment is not limited to this. An electrode hole 731 may be formed in one of the pair of curved portions 711 (particularly the curved portion 711 in the negative Z-axis direction) at a position that does not overlap with the injection hole 131 when viewed from the Z-axis direction, or an electrode hole 731 may not be formed at all. If the electrode hole 731 of the curved portion 711 in the negative Z-axis direction is positioned so as not to face the electrode hole 731 of the curved portion 711 in the positive Z-axis direction in the Z-axis direction, the electrolyte will penetrate from a different position than the electrode hole 731 of the curved portion 711 in the positive Z-axis direction, thereby improving the penetration into the electrode body 700. Multiple electrode holes 731 aligned in the X-axis direction may be formed in the curved portion 711 in the negative Z-axis direction. This will improve the penetration into the electrode body 700.

[0092] In the above embodiment, electrode holes 731 are formed continuously from the outermost layer 713a to the innermost layer 713a of the electrode body 700, but the embodiment is not limited to this. Electrode holes 731 may be formed intermittently from the outermost layer 713a to the innermost layer 713a of the electrode body 700. In the above modified example 1, electrode holes 731 are formed in the outer peripheral portion 711b and not in the inner peripheral portion 711a, but they may also be formed in the inner peripheral portion 711a and not in the outer peripheral portion 711b.

[0093] In the above embodiment, the active material layer is arranged around the electrode hole 731, but the active material layer may be arranged with a slight gap from the electrode hole 731.

[0094] In the above embodiment, the electrode hole 731 is assumed to be elongated in the Y-axis direction, but it is not limited to this. The electrode hole 731 may be elongated in a direction inclined from the Y-axis direction, or it may be elongated in the X-axis direction. The electrode hole 731 may be circular, square, equilateral triangle, etc., when viewed from the Z-axis direction, and may not be elongated in either the X-axis direction or the Y-axis direction.

[0095] In the above embodiment, the electrode hole 731 is formed in the central part of the electrode body 700 and not at the end of the electrode body 700 when viewed from the Z-axis direction, but is not limited to this. The electrode hole 731 may be formed at the end of the electrode body 700 in addition to the central part of the electrode body 700 when viewed from the Z-axis direction, or instead of the central part of the electrode body 700. In this case, the position of the injection hole 131 may also be appropriately changed so that the electrode hole 731 is positioned to overlap with the injection hole 131 when viewed from the direction of penetration of the injection hole 131.

[0096] In the above embodiment, the electrode hole 731 is formed in the curved portion 711 of the electrode body 700, but it may also be formed in the flat portion 712 in addition to the curved portion 711. In other words, the electrode hole 731 may penetrate in a direction perpendicular to the penetrating direction of the liquid injection hole 131. Alternatively, the electrode hole 731 may be formed in the flat portion 712 instead of the curved portion 711 of the electrode body 700. In this case, the position of the liquid injection hole 131 may also be appropriately changed (for example, formed in the long side wall portion 111 or the short side wall portion 112 of the container 100) so that the electrode hole 731 is positioned to overlap with the liquid injection hole 131 when viewed from the penetrating direction of the liquid injection hole 131.

[0097] In the above embodiment, the electrode body 700 is assumed to have an elongated shape extending in the X-axis direction, but it does not have to be elongated.

[0098] In the above embodiment, the electrode body 700 is an elongated cylindrical shape (flattened shape) having a curved portion 711 and a flat portion 712, but it may also be cylindrical or elliptical, and its shape is not particularly limited. In the electrode body 700, the portion 720 where the active material layer is not formed may be a tab portion (a portion where multiple tabs of the electrode plate are stacked) protruding from a part of the electrode body main body portion 710.

[0099] In the above embodiment, the electrode body 700 is a wound-type electrode body formed by winding an electrode plate on a winding axis parallel to the X-axis direction, but it may also be a wound-type electrode body formed by winding an electrode plate on a winding axis parallel to the Z-axis direction. The electrode body 700 may also be a stacked type electrode body formed by stacking a plurality of flat electrode plates, a bellows-type electrode body formed by folding an electrode plate in a bellows shape, or an electrode body of any other form. In these cases, the position of the injection hole 131 may be appropriately changed (e.g., formed in the long side wall portion 111 or the short side wall portion 112 of the container 100) so that the electrode hole 731 is positioned to overlap with the injection hole 131 when viewed from the direction of penetration of the injection hole 131.

[0100] In the above embodiment, the separator 760 may be provided with an inorganic coating layer. The inorganic coating layer is a coating layer containing inorganic particles and a binder, and the binder may coat (coat) the entire or a part of the surface (one or both sides) of the separator 760. As the binder, appropriately known materials can be used. Preferably, the inorganic coating layer contains at least one of aluminum silicate, barium sulfate, and alumina (boehmite) as inorganic particles. The inorganic coating layer has an electrolyte penetration area of ​​80 mm² at 300 seconds after the electrolyte is dropped onto it. 2The above is preferable. When a sheet-like member is placed on the outer surface of the electrode body 700, an insulating sheet-like porous body may be placed. The porous body preferably has larger pores (100 μm or more) than the separator 760, and therefore has lower air permeability than the separator 760 (air permeability of 250 seconds / 100 mL or less). The porous body preferably has been formed from a nonwoven fabric such as a polymer nonwoven fabric made of PP. As a result, the permeability of the electrolyte to the electrode body 700 is improved, and the number of electrode pore groups 730 or electrode pores 731 formed in the electrode body 700 can be reduced.

[0101] The present invention also includes forms constructed by arbitrarily combining the components included in the above embodiments and their modified examples. [Industrial applicability]

[0102] This invention can be applied to energy storage elements such as lithium-ion secondary batteries. [Explanation of Symbols]

[0103] 10, 11 Energy storage elements 20 Energy storage units 30 Energy storage devices 100 containers 110 Container body 120 Lid 130 Injection section 131 Liquid injection hole 132 Injection Plug 300 terminals 600 Current collector 700, 700a electrode body 710 Electrode body part 711 Curved section 711a Inner circumference 711b outer periphery 712 Flat area 713 Active material layer forming part 713a layer 720 Active material layer non-forming area 730, 730a Electrode hole group 731 Electrode hole 740 Positive Plate 740a Positive electrode hole 741 Positive electrode current collector foil 742 Cathode active material layer 750 Negative plate 750a Negative electrode hole 751 Negative electrode current collector foil 752 Negative electrode active material layer 760, 761, 762 Separators

Claims

1. It comprises an electrode body in which electrode plates are stacked, and a container in which the electrode body is housed, The electrode plate comprises a current collector foil and an active material layer, and also includes an electrode hole which is a through hole that penetrates both the current collector foil and the active material layer. The container is equipped with an injection port for pouring in the electrolyte, The electrode hole is positioned so as to overlap with the injection hole when viewed from the direction through which the injection hole penetrates. Energy storage element.

2. The active material layer is arranged around the electrode hole. The energy storage element according to claim 1.

3. The electrode hole is elongated in a predetermined direction when viewed from the through-direction. The energy storage element according to claim 1 or 2.

4. The electrode body is formed by winding the electrode plate, The electrode holes are not formed in the inner circumference portion of the electrode plate, which is closer to the innermost circumference than the outermost circumference, but rather in the outer circumference portion of the electrode plate, which is closer to the outermost circumference than the innermost circumference. The energy storage element according to claim 1 or 2.

5. The electrode holes are formed in the central part of the electrode body, and not at the ends of the electrode body when viewed from the through-direction. The energy storage element according to claim 1 or 2.

6. The electrode hole does not penetrate in a direction perpendicular to the penetration direction, but penetrates in a direction perpendicular to the penetration direction or in a direction intersecting the penetration direction. The energy storage element according to claim 1 or 2.

7. The aforementioned electrode plate comprises a positive electrode plate and a negative electrode plate. The positive electrode plate and the negative electrode plate are each formed with a plurality of positive electrode holes and a plurality of negative electrode holes, respectively. The plurality of positive electrode holes and the plurality of negative electrode holes are arranged to overlap when viewed from the through direction. The energy storage element according to claim 1 or 2.

Images