Electricity storage device

Abstract

A power storage device is provided with: a power storage element; and a holding unit that is disposed further to the outside than the power storage element and holds the power storage element, the power storage element being provided with: an electrode body around which a pole plate is wound; and a container for accommodating the electrode body, the electrode body having a flat shape provided with a pair of opposed flat portions and a pair of opposed curved portions, the container being provided with: a flat wall portion opposed to the flat portions of the electrode body; and a curved wall section facing the curved section of the electrode body, the inner surface of the flat wall section being a flat shape along the flat section, the inner surface of the curved wall section being a curved shape along the curved section, the inner surface of the holding unit being provided with: a flat surface being a flat shape along the outer surface of the flat wall section of the container; and a curved surface having a curved shape along the outer surface of the curved wall portion of the container, the inner surface of the flat wall portion of the container presses the flat portion of the electrode body, the inner surface of the curved wall portion of the container presses the curved portion of the electrode body, and the flat surface of the holding unit presses the outer surface of the flat wall portion of the container. The curved surface of the holding unit presses the outer surface of the curved wall portion of the container.

Description

Technical Field

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

[0002] For example, Patent Document 1 discloses a non-aqueous electrolyte battery in which a wound electrode body is built into a square container.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2010-73580 Summary of the Invention

[0006] -The problem the invention aims to solve-

[0007] In conventional batteries where wound electrodes are housed in a rectangular container, the internal space of the container is rectangular, and therefore the inner wall of the container does not run along the outer surface of the curved portion of the electrode. If the electrode expands due to charging and discharging, this expansion tends to occur more readily in the curved portion of the electrode, where it is not compressed by the inner wall of the container. As a result, tensile stress (reaction force) concentrates between the curved and flat portions of the electrode, leading to deterioration of the electrode and causing capacity reduction, which can result in plate damage, lithium deposition, and other adverse effects. Furthermore, when using active materials that expand significantly, substantial deformation can occur, potentially leading to foil breakage.

[0008] The purpose of this invention is to provide an energy storage device that can prevent deformation of the electrode body, which may be a cause of lithium electrode deposition, and suppress damage to the electrode body, even when using an active material that expands significantly.

[0009] -Methods for solving problems-

[0010] An embodiment of the present invention relates to an energy storage device comprising: an energy storage element; and a holding unit disposed further outward than the energy storage element and holding the energy storage element, the energy storage element comprising: an electrode body wound with electrode plates; and a container housing the electrode body, the electrode body being a flat shape having a pair of opposing flat portions and a pair of opposing curved portions, the container comprising: a flat wall portion opposing the flat portions of the electrode body; and a curved wall portion opposing the curved portions of the electrode body, the inner surface of the flat wall portion following the flat shape of the flat portion, and the inner surface of the curved wall portion following the flat shape of the flat portion. The bending shape of the bending portion is described above. The inner surface of the holding unit includes: a flat surface, which is a flat shape along the outer surface of the flat wall portion of the container; and a bending surface, which is a bending shape along the outer surface of the bending wall portion of the container. The inner surface of the flat wall portion of the container presses against the flat portion of the electrode body, the inner surface of the bending wall portion of the container presses against the bending portion of the electrode body, the flat surface of the holding unit presses against the outer surface of the flat wall portion of the container, and the bending surface of the holding unit presses against the outer surface of the bending wall portion of the container.

[0011] -Invention Effects-

[0012] According to the present invention, an energy storage device is provided that can prevent deformation of the electrode body, which may be a cause of lithium electrode deposition, and can suppress damage to the electrode body. Attached Figure Description

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

[0014] Figure 2 This is an exploded perspective view showing the constituent elements of the energy storage device according to the embodiment after disassembly.

[0015] Figure 3 This is a perspective view showing the appearance of the energy storage element involved in the embodiment.

[0016] Figure 4 It is an exploded perspective view that shows the constituent elements of the energy storage element involved in the implementation method.

[0017] Figure 5 This is a perspective view showing the structure of the electrode body involved in the embodiment.

[0018] Figure 6 This is an explanatory diagram showing the holding unit, housing, and various energy storage elements involved in the implementation method.

[0019] Figure 7This is a cross-sectional view showing the state of the square container containing the electrode body involved in Comparative Example 1.

[0020] Figure 8 This is a cross-sectional view showing the state of the square container containing the electrode body involved in Comparative Example 2.

[0021] Figure 9 It is a cross-sectional view showing the positional relationship between the holding unit, container and electrode body involved in the embodiment.

[0022] Figure 10 This is an explanatory diagram showing the retaining unit, housing, and various energy storage elements involved in Modified Example 1.

[0023] Figure 11 This is an explanatory diagram showing the retaining unit, housing, and various energy storage elements involved in Modified Example 2.

[0024] Figure 12 This is a perspective view showing the appearance of the energy storage element involved in Modification Example 3.

[0025] Figure 13 This is a perspective view showing the appearance of the energy storage element involved in Modification Example 4.

[0026] Figure 14 This is a perspective view showing the appearance of the energy storage element involved in Modification Example 5.

[0027] Figure 15 This is a perspective view showing the appearance of the energy storage element involved in Modification Example 6.

[0028] Figure 16 This is a perspective view showing the appearance of the energy storage element involved in Modification Example 7. Detailed Implementation

[0029] (The inventors' insights)

[0030] The inventors considered the following: by making the inner surface of the container wall (bent wall) opposite the bent portion of the electrode body follow the curved shape of the bent portion, the space between the bent portion of the electrode body and the bent wall is reduced. This avoids the situation where the expansion of the bent portion of the electrode body is more likely to occur than the expansion of the flat portion of the electrode body when using a square container. It also reduces the difference in the ease of expansion between the bent portion and the flat portion of the electrode body. Furthermore, by setting the container to press against the electrode body, the tensile stress generated in the bent portion of the electrode body and between the bent and flat portions is suppressed. Here, considering the possibility that the strength of the container wall cannot withstand the expansion of the bent portion of the electrode body, resulting in container deformation and insufficient pressure on the electrode body, the inventors studied an energy storage device equipped with a holding unit. Moreover, they discovered a structure in which a curved surface is provided on the inner surface of the holding unit, following the curved shape of the outer surface of the bent wall of the container. When the container is pressed by the holding unit, the electrode body is pressed against the container. Therefore, the pressure from the holding unit is transmitted to the electrode body through the container, applying a compressive force to the electrode body exceeding the strength of the container wall, thus suppressing deformation of the container caused by the expansion of the electrode body. As a result, the tension generated at the boundary between the flat and curved portions of the electrode body can be suppressed, thereby preventing defects in the electrode body.

[0031] (1) The device comprises: an energy storage element; and a holding unit disposed further outward than the energy storage element and holding the energy storage element, the energy storage element comprising: an electrode body wound with electrode plates; and a container housing the electrode body, the electrode body being a flat shape having a pair of opposing flat portions and a pair of opposing curved portions, the container comprising: a flat wall portion opposing the flat portions of the electrode body; and a curved wall portion opposing the curved portions of the electrode body, the inner surface of the flat wall portion being along the flat shape of the flat portion, and the inner surface of the curved wall portion being along the curved shape of the curved portion. The retaining unit has a curved shape, and its inner surface includes: a flat surface, which is a flat shape along the outer surface of the flat wall portion of the container; and a curved surface, which is a curved shape along the outer surface of the curved wall portion of the container. The inner surface of the flat wall portion of the container presses against the flat portion of the electrode body, the inner surface of the curved wall portion of the container presses against the curved portion of the electrode body, the flat surface of the retaining unit presses against the outer surface of the flat wall portion of the container, and the curved surface of the retaining unit presses against the outer surface of the curved wall portion of the container.

[0032] According to one aspect of the present invention, the energy storage device includes a container comprising a flat wall portion opposite to the flat portion of the electrode body and a curved wall portion opposite to the curved portion of the electrode body. The inner surface of the flat wall portion, which forms a flat shape along the flat portion of the electrode body, presses against the flat portion of the electrode body, and the inner surface of the curved wall portion, which forms a curved shape along the curved portion of the electrode body, presses against the curved portion of the electrode body. In this way, by making both the flat portion and the curved portion of the electrode body press against the container, the space (residual space) generated between the curved portion of the electrode body and the inner surface of the container in the case of conventional square containers can be eliminated, and the situation where the expansion of the curved portion of the electrode body is relatively more likely to occur than the expansion of the flat portion of the electrode body can be suppressed.

[0033] In conventional structures that house wound electrode bodies within a square container, the following explains how the electrode body typically expands. During the early stages of the energy storage element's lifespan, the electrode plates constituting the flat portion of the electrode body expand in the thickness direction and extend in the length direction. However, towards the end of the energy storage element's lifespan, the thickness-direction expansion of the electrode body is restricted by the pressure from the inner surface of the container, increasing the friction between the inner surface and the electrode body. This makes the extension of the electrode plates in the length direction difficult. On the other hand, in the curved portion of the electrode body, even towards the end of the energy storage element's lifespan, a space remains between the electrode body and the inner surface of the container (residual space), and the length-direction extension of the electrode plates continues. Therefore, strong tensile stress is generated on the electrode plates located at the boundary between the flat and curved portions of the electrode body, which, in the worst case, can sometimes lead to electrode breakage. Therefore, the inventors designed an energy storage device according to one aspect of the present invention, in which the container of the energy storage element using a wound electrode body is formed in a shape along the outer periphery (outer surface) of the electrode body, the electrode body is pressed by the container, and a holding unit constructed along the outer periphery (outer surface) of the container is used to press the outer surface of the container.

[0034] Specifically, in the case of the electricity storage device as one mode of the present invention, it is in the following state: while the flat portion of the electrode body is pressed by the flat wall portion of the container and the curved portion of the electrode body is pressed by the curved wall portion of the container, the flat surface of the holding unit presses the outer surface of the flat wall portion of the container, and the curved surface of the holding unit presses the outer surface of the curved wall portion of the container. That is, the holding unit can perform pressing of the flat portion of the electrode body via the flat wall portion of the container and pressing of the curved portion of the electrode body via the curved wall portion of the container. Thereby, a pressing force that combines the pressing force from the flat wall portion of the container and the pressing force from the flat surface of the holding unit is applied to the flat portion of the electrode body. Similarly, a pressing force that combines the pressing force from the curved wall portion of the container and the pressing force from the curved surface of the holding unit is applied to the curved portion of the electrode body. Thereby, a large pressing force that is sufficient to suppress the expansion of the electrode body and exceeds the strength of the container is applied to the electrode body, and deformation of the container caused by the expansion of the electrode body can also be suppressed. As a result, the tension generated at the boundary between the flat portion and the curved portion of the electrode body can be suppressed, and adverse conditions of the electrode body can be suppressed. Examples of the adverse conditions of the electrode body include damage to the electrode body caused by a decrease in the capacity of the deformed storage element that may cause lithium deposition, foil breakage, and the like. In addition, the stress applied to the container and the holding unit is designed to be within the elastic range of their respective materials.

[0035] (2) In the electricity storage device described in (1) above, it may also be provided with an external member or a housing disposed more outward than the holding unit, the external member or the housing fixing or housing the holding unit, and the outer surface of the holding unit being pressed by the external member or the housing, so as to be in a state where the curved surface of the holding unit presses the outer surface of the curved wall portion of the container of the electricity storage element and the flat surface of the holding unit presses the outer surface of the flat wall portion of the container of the electricity storage element.

[0036] According to the energy storage device described in (2) above, a large pressure is applied to the curved portion of the electrode body by three factors: the pressure from the external component or housing, the pressure from the curved surface of the holding unit, and the pressure from the curved wall of the container. At this time, the curved surface of the inner surface of the holding unit can also be said to be in a state of pressing the curved wall of the container, and a large pressure is applied to the curved wall of the container by the pressure from the external component or housing and the pressure from the holding unit. Furthermore, the deformation of the container caused by the expansion of the curved portions of each electrode body can be suppressed more reliably. In addition, each curved portion of the electrode body is compressed from each curved wall of the container, and each flat portion of the electrode body is compressed from each flat wall of the container. Therefore, expansion is suppressed in both the curved portions and the flat portions of the electrode body, thereby suppressing the increase of tensile stress at the boundary between the curved and flat portions. As a result, the expansion of the curved portions of the electrode body and the deformation of the container caused therefrom can be further suppressed, and as a result, the foil breakage of the electrode body can be further suppressed. Here, in examples of methods for applying pressure to the retaining unit from an external component or housing, there are methods such as: pressing a monolithic assembly (block) that integrates the retaining unit and the energy storage element into a housing of a fixed size while applying pressure; and placing the monolithic assembly (block) that integrates the retaining unit and the energy storage element in a housing of a fixed size, inserting a component between the housing and the block, and applying pressure. Furthermore, the method of applying pressure to the retaining unit from an external component or housing in this invention is not limited to the examples shown.

[0037] (3) In the energy storage device described in (2) above, the holding unit may also include: a plurality of holding members arranged in a direction opposite to the flat portion of the electrode body and the flat wall portion of the container, the inner surface of the holding member having: the flat surface that presses against the outer surface of the flat wall portion of the container; and the curved surface that presses against the outer surface of the curved wall portion of the container.

[0038] According to the energy storage device described in (3) above, each retaining member integrally has a flat surface that presses against the flat wall portion and a curved surface that presses against the curved wall portion. Therefore, the retaining members can suppress both the expansion of the flat portion of the electrode body through the flat wall portion of the container and the expansion of the curved portion of the electrode body through the curved wall portion of the container. That is, the entire electrode body can be pressed using an energy storage device with a simple structure, and as a result, the defects of the electrode body can be suppressed more reliably.

[0039] (4) In the energy storage device described in (2) above, the holding unit may also include: a pair of first holding members that clamp the energy storage element in the direction opposite to the curved portion of the electrode body and the curved wall portion of the container; and a pair of second holding members that clamp the energy storage element in the direction opposite to the flat portion and the flat wall portion, wherein the pair of first holding members are separate from the pair of second holding members, the inner surface of the first holding members has a curved surface that presses against the curved wall portion of the container, and the inner surface of the second holding members has a flat surface that presses against the flat wall portion of the container.

[0040] According to the energy storage device described in (4) above, since the first holding member and the second holding member are separate, the first holding member and the second holding member can be installed separately, making it easier to manufacture the energy storage device. Furthermore, the pressure applied from the first holding member to the curved wall portion of the container and the pressure applied from the second holding member to the flat wall portion of the container can be adjusted separately. Therefore, even if the size of the energy storage element changes due to design or model changes, as long as the shape of the container remains partially the same, either the first holding member or the second holding member can be used to reduce manufacturing costs.

[0041] (5) In the energy storage device described in (4) above, it may also include a plurality of energy storage elements, the plurality of energy storage elements including a first energy storage element and a second energy storage element. The first energy storage element includes: a first electrode body having the same structure as the electrode body; and a first container having the same structure as the container. The first electrode body is a flat shape having a first flat portion having the same structure as the flat portion and a first curved portion having the same structure as the curved portion. The first container includes: a first flat wall portion having the same structure as the flat wall portion; and a first curved wall portion having the same structure as the curved wall portion. The second energy storage element includes: a second electrode body having the same structure as the electrode body; and a second container having the same structure as the container. The second electrode body is a flat shape having a second flat portion having the same structure as the flat portion and a second curved portion having the same structure as the curved portion. The container includes: a second flat wall portion having the same structure as the flat wall portion; and a second curved wall portion having the same structure as the curved wall portion, configured such that the face of the first flat wall portion of the first container of the first energy storage element and the face of the second flat wall portion of the second container of the second energy storage element face each other. The inner surface of the first retaining member has a plurality of curved surfaces integrally provided, the plurality of curved surfaces including: a first curved surface facing the first curved wall portion; and a second curved surface facing the second curved wall portion. The first curved portion of the first electrode body is compressed by the first curved surface of the first retaining member pressing the outer surface of the first curved wall portion in the first container, and the second curved portion of the second electrode body is compressed by the second curved surface of the first retaining member pressing the outer surface of the second curved wall portion in the second container.

[0042] According to the energy storage device described in (5) above, the multiple curved surfaces (first curved surface, second curved surface) of the first retaining member face each curved wall portion of the multiple energy storage elements (first energy storage element, second energy storage element), so the multiple curved surfaces (first curved surface, second curved surface) of the first retaining member can press the multiple curved wall portions (first curved wall portion, second curved wall portion) together. In addition, compared with the case where one first retaining member is arranged for each curved wall portion, the number of first retaining members is less, so the assembly of the energy storage device becomes easier. In addition, here, the first energy storage element and the second energy storage element are used for description, but it goes without saying that a first retaining member may also have multiple curved surfaces facing each curved wall portion of two or more multiple energy storage elements.

[0043] (6) In the energy storage device described in (1) to (5) above, the holding unit may also be formed of foamed resin.

[0044] According to the energy storage device described above (6), since the retaining unit is made of foamed resin, it is easy to form along the shape of the curved wall of the container during manufacturing. In addition, by forming the retaining unit with foamed resin, it is possible to achieve lightweight and easy manufacturing. Various methods of forming the retaining unit with foamed resin can be considered. The retaining unit can be formed by filling foamed resin and curing it after arranging the energy storage element in the energy storage device, or by assembling the pre-formed components constituting the retaining unit together with the energy storage element, etc. The retaining unit can also be composed of a part that is filled with foamed resin and cured in the energy storage device and a part that is pre-formed before the assembly of the energy storage device. For example, after positioning the energy storage element and a second retaining member (part of the retaining unit) opposite to the flat wall of the energy storage element in the energy storage device, foamed resin can be filled to form a first retaining member (part of the retaining unit) opposite to the curved wall of the energy storage element. In addition, in this example, the second retaining member (part of the retaining unit) whose shape is determined by pre-forming is arranged in the energy storage device together with the energy storage element. Furthermore, the second retaining component (part of the retaining unit) can be formed of foamed resin or of a material different from foamed resin. Alternatively, the retaining unit can be formed by filling and curing the foamed resin once or multiple times after positioning and configuring the energy storage element. The components of the retaining unit, pre-formed and shaped, can also be assembled together with the energy storage element. Even if the retaining unit is made of foamed resin, it possesses sufficient strength and is formed of a material with elastic regions sufficient to suppress the expansion of the electrode body. Furthermore, the retaining unit can be entirely formed of foamed resin, or only a portion of the retaining unit can be formed of foamed resin.

[0045] (7) In the energy storage device described in (1) to (6) above, the holding unit may also have a refrigerant path for refrigerant flow.

[0046] According to the energy storage device described in (7) above, since the holding unit has a refrigerant path, the container can be cooled efficiently via the holding unit. Furthermore, it is known that if a heating medium is allowed to flow through the refrigerant path, it can be used as a heating method.

[0047] (Implementation Method)

[0048] Hereinafter, the energy storage element and energy storage device according to embodiments of the present invention (including variations thereof) 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 do not limit the scope of the present invention. Dimensions are not strictly illustrated in the figures. The same reference numerals are used to denote the same constituent elements in the figures. The names of the constituent components (constituent elements) in this embodiment are those used in this embodiment and may sometimes differ from the names of the constituent components (constituent elements) in the background art.

[0049] In the following description and accompanying drawings, the length direction of the energy storage element and the winding axis direction of the electrode body of the energy storage element are defined as the X-axis direction. The arrangement direction of multiple energy storage elements and the thickness direction of the energy storage element container are defined as the Y-axis direction. The arrangement direction, or vertical direction, of the housing cover and housing body of the energy storage device is defined as the Z-axis 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 vertical is also considered, but for ease of explanation, the Z-axis direction will be described as vertical below.

[0050] In the following description, "insulating" refers to "electrical insulation." The insulating material is preferably made of material with a volume resistivity of 1 × 10⁻⁶. 10 Materials with an Ωm or greater are formed.

[0051] In the following explanation, the positive X-axis direction represents the direction of the arrow on the X-axis, and the negative X-axis direction represents the direction opposite to the positive X-axis direction. The same applies to the Y-axis and Z-axis directions. Furthermore, the representations of parallel and orthogonal directions or orientations strictly include cases where the direction or orientation is not that specific. Two orthogonal directions not only mean that the two directions are completely orthogonal, but also that they are substantially orthogonal, i.e., including a difference of about a few percent.

[0052] [Description of the energy storage device]

[0053] First, the general structure of the energy storage device 1 in this embodiment will be described. Figure 1 This is a perspective view showing the appearance of the energy storage device 1 according to the embodiment. Figure 2 This is an exploded perspective view showing the constituent elements of the energy storage device 1 according to the embodiment after disassembly.

[0054] The energy storage device 1 is a device capable of charging electricity from an external source or discharging it to an external source. In this embodiment, it has a generally rectangular parallelepiped shape. Here, a rectangular parallelepiped is defined as a hexahedron whose faces are all composed of rectangles or squares. The energy storage device 1 is an energy storage element module (battery pack) used for purposes such as electricity storage or power supply. Specifically, the energy storage device 1 is used as a battery for driving or starting the engine of moving vehicles such as automobiles, motorcycles, watercraft, ships, snowmobiles, agricultural machinery, construction machinery, automated guided vehicles (AGVs), or railway vehicles for electrified 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.) automobiles. Examples of railway vehicles for electrified railways include trams, monorails, linear electric locomotives, and hybrid trams equipped with both diesel engines and electric motors. The energy storage device 1 can also be used as a stationary battery for household or commercial use.

[0055] like Figure 1 as well as Figure 2 As shown, the energy storage device 1 includes a housing 2. Inside the housing 2 are housed a plurality of energy storage elements 10, a holding unit 20, a pair of venting members 50, and a plurality of busbars (not shown). The energy storage device 1 also includes external terminals (positive external terminal and negative external terminal) for electrical connection with external devices, but their illustrations and descriptions are omitted. In addition to the above-mentioned components, the energy storage device 1 may also include restraining members (end plates, side plates, etc.) for restraining the plurality of energy storage elements 10, busbar retainers for holding the busbars, busbar covers, circuit boards for monitoring or controlling the charging and discharging states of the energy storage elements 10, relays, fuses, shunt resistors, connectors, and other electrical components.

[0056] The housing 2 is a generally rectangular (box-shaped) container (shell) constituting the outer body (casing, outer shell) of the energy storage device 1. The housing 2 is an example of an external component. The housing 2 is disposed outside the plurality of energy storage elements 10 and the holding unit 20, etc., pressing against them. The housing 2 is a metal shell formed from metal components such as aluminum, aluminum alloy, stainless steel, iron, or electroplated steel sheet. The housing 2 may also be formed from insulating components such as resin materials. When the housing 2 is formed from a conductive material, the inner surface of the housing 2 may be covered with an insulating material to ensure insulation from the energy storage elements 10.

[0057] like Figure 2As shown, the housing 2 includes a housing body 30 that constitutes the main body of the housing 2 and a housing cover 40 that constitutes the cover of the housing 2. The housing body 30 is a bottomed rectangular cylindrical housing (shell) with an opening 31 formed in the positive Z-axis direction, which houses multiple energy storage elements 10 and a holding unit 20, etc.

[0058] Specifically, the housing body 30 has a bottom wall 32 and a side wall 33. The bottom wall 32 is a flat and rectangular portion located at the end of the housing body 30 in the negative Z-axis direction.

[0059] The sidewall 33 is a rectangular annular wall extending from the outer periphery of the bottom wall 32 in the positive Z-axis direction, and is continuously arranged around the entire circumference of the bottom wall 32. The inner side of the sidewall 33 has an opening 31. A pair of exhaust ports 37 are provided on the sidewall 33, which in this embodiment are located in the negative Z-axis direction within the sidewall 33. One of the exhaust ports 37 is located in both the negative Z-axis and negative X-axis directions, and the other exhaust port 37 is located at a corner in both the negative Z-axis and positive X-axis directions. In other words, both exhaust ports 37 are located at the corners of the housing body 30. Each exhaust port 37 connects the interior and exterior of the housing 2, discharging gas discharged from each energy storage element 10 to the outside of the housing 2.

[0060] The shell cover 40 is a flat, rectangular component that blocks the rectangular opening 31 of the shell body 30. The shell body 30 and the shell cover 40 are joined by welding, fusion, threaded fixing, etc., and the shell 2 is sealed. The shell body 30 and the shell cover 40 can be formed from components of the same material or from components of different materials.

[0061] The energy storage element 10 has a shape in which its length in the X-axis direction is longer than its length in the Y-axis direction; specifically, it has a flat, elongated cylindrical shape in the Y-axis direction. In this embodiment, eight energy storage elements 10 are arranged in the Y-axis direction. The size of the energy storage elements 10 and the number of arranged energy storage elements 10 are not particularly limited; a single energy storage element 10 may also be used. Each energy storage element 10 may also be covered by an insulating film. A detailed description of the structure of the energy storage element 10 will be provided later.

[0062] The holding unit 20 holds each energy storage element 10. In this embodiment, the holding unit 20 includes a plurality of holding members 21 arranged along the Y-axis direction. An energy storage element 10 is disposed between two adjacent holding members 21 in the Y-axis direction. Details of the holding unit 20 will be described later.

[0063] The venting member 50 is a component that forms a flow path for the gas discharged from at least one energy storage element 10 to flow to the outside of the housing 2. In this embodiment, the energy storage device 1 includes a pair of venting members 50. Each venting member 50 is disposed at its end in the X-axis direction within the housing body 30, and is a component whose surface faces and covers the gap between each energy storage element 10 and each holding member 21.

[0064] The exhaust component 50 has a first plate portion 51 and a second plate portion 52 bent relative to the first plate portion 51. The first plate portion 51 is a rectangular plate-shaped portion that is parallel to the YZ plane and elongated in the Y-axis direction. The second plate portion 52 is a rectangular plate-shaped portion that is parallel to the XY plane and elongated in the Y-axis direction. The first plate portion 51 overlaps with a portion of the second recess 102 of each energy storage element 10 constituting the space S2. The second plate portion 52 overlaps with another portion of the second recess 102 of each energy storage element 10 constituting the space S2. Thus, within the space S2, the gaps between adjacent energy storage elements 10 and between adjacent energy storage elements 10 and the holding member 21 are covered by the first plate portion 51 and the second plate portion 52.

[0065] In the second plate portion 52, a plurality of vent holes 53 are provided at positions corresponding to the gas discharge valves 800 of each energy storage element 10. When the gas discharge valve 800 of a given energy storage element 10 opens and gas is discharged, the gas enters the space S2 through the vent holes 53. Here, the vent holes 53 are preferably larger than the gas discharge valves 800. An annular sealing material may also be disposed around the vent holes 53 between the second plate portion 52 and the energy storage element 10. The sealing material is formed of rubber or porous resin. The sealing material is used to suppress gas leakage to the outside of the space S2. The gas flows in the space S2 and is discharged from the exhaust port 37. At this time, the exhaust member 50 covers the gaps between adjacent energy storage elements 10 and between adjacent energy storage elements 10 and the retaining member 21, thus suppressing gas intrusion into these gaps. Here, an L-shaped exhaust member 50 is shown when viewed from the Y-axis direction, but it may also be U-shaped or triangular. Regardless of the shape, as long as a vent is formed at the location corresponding to the gas discharge valve of each energy storage element, it is acceptable.

[0066] The busbar is connected (joined) to the terminals 300 of multiple energy storage elements 10. Specifically, the multiple busbars connect the terminals 300 of two adjacent energy storage elements 10 to each other, and electrically connect the terminals 300 of the end energy storage elements 10 to external terminals. The connection method of the busbars is not particularly limited; multiple energy storage elements 10 can be connected in series or parallel in any combination, or all energy storage elements 10 can be connected in series or parallel. The busbars are connected (joined) to the terminals 300 by welding or the like, but the connection method is not particularly limited. The busbars are formed of conductive components made of metals such as aluminum, aluminum alloys, copper, copper alloys, Ni, or combinations thereof, or conductive components other than metals.

[0067] [Description of Energy Storage Components]

[0068] use Figure 3 as well as Figure 4 The energy storage element 10 in the implementation method will be described in its entirety. Figure 3 This is a perspective view showing the appearance of the energy storage element 10 according to the embodiment. Figure 4 This is an exploded perspective view showing the components of the energy storage element 10 according to the embodiment.

[0069] The energy storage element 10 is an energy storage element capable of charging from external sources or discharging to external sources. The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery, but can also be a secondary battery other than a non-aqueous electrolyte secondary battery. The energy storage element 10 can be an all-solid-state lithium battery using a solid electrolyte, or a polymer lithium battery. The energy storage element 10 can also be a pouch-type energy storage element. In this embodiment, an energy storage element 10 based on a flat, elongated cylindrical shape is illustrated, but the shape of the energy storage element 10, i.e., the shape of the container 100, is not limited to a flat, elongated cylindrical shape. As long as it follows the shape of the outer surface of the electrode body 700 described later, it can also be based on a polygonal prism shape, an elliptical cylinder shape, or a cylindrical shape, etc.

[0070] like Figure 3 as well as Figure 4As shown, in this embodiment, the energy storage element 10 includes a container 100, a pair of terminals 300, and a pair of outer gaskets 400 on the outside of the container 100, and a pair of inner gaskets 500, a pair of current collectors 600, and an electrode body 700 housed inside the container 100. Specifically, the components of the positive electrode are disposed on the outer surface of the container 100 in the positive X-axis direction, i.e., the first side surface portion 110. Examples of the components of the positive electrode include the terminals 300, the outer gaskets 400, the inner gaskets 500, and the current collectors 600. In other words, the first side surface portion 110 constitutes the outer surface of the cover 170 covering the end of the container 100 in the positive X-axis direction, and the components of the positive electrode are disposed on the first side surface portion 110. In this embodiment, the first side portion 110 is a portion in the X-axis direction that is within the range of 1% to 10% of the length of the container 100 from the end face of the container 100 in the positive X-axis direction. However, if the length of the container 100 in the X-axis direction is less than 3 times the length of the container 100 in the Z-axis direction, the length of the container 100 in the X-axis direction may be greater than 10%.

[0071] The negative electrode components are disposed on the outer surface of the container 100 in the negative X-axis direction, i.e., the second side surface portion 120. Examples of the negative electrode components include the terminal 300, the outer gasket 400, the inner gasket 500, and the current collector 600. In other words, the second side surface portion 120 is the surface that forms the outer surface of the cover 170 covering the end of the container 100 in the negative X-axis direction, and the negative electrode components are disposed on the second side surface portion 120. The second side surface portion 120 is a portion in the X-axis direction within the range of 1% to 10% of the length of the container 100 from the end face of the container 100 in the negative X-axis direction. However, if the length of the container 100 in the X-axis direction is less than three times the length of the container 100 in the Z-axis direction, the range of the length of the container 100 in the X-axis direction can be greater than 10%.

[0072] An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, 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. In addition to the above-mentioned components, spacers may be provided on the side, above or below the electrode body 700, and an insulating film may be provided to enclose the electrode body 700, etc.

[0073] Container 100 is a shell having a shape based on an elongated cylinder that is long in the X-axis direction and flat in the Y-axis direction. In this embodiment, the length of container 100 in the X-axis direction is at least three times the length of container 100 in the Z-axis direction, and the length of container 100 in the X-axis direction is at least five times the length of container 100 in the Y-axis direction. Figure 3In the diagram, a long cylindrical region that serves as the reference for the shape of the container 100 is illustrated by a double-dotted line L1. In this embodiment, the container 100 has notches at each end in the winding axis direction (X-axis direction) of the electrode body 700, at the end in the positive Z-axis direction, and at the end in the negative Z-axis direction. Alternatively, the container 100 has two notches (a pair of notches) at the end in the positive X-axis direction and two notches (a pair of notches) at the end in the negative X-axis direction, for a total of four notches (a pair of notches). Each notch is a corner missing portion of the container 100, and when viewed from the Y-axis direction, the missing portion appears rectangular. In other words, the shape of the container 100 is such that, for a long cylindrical shape that is elongated in the X-axis direction and flattened in the Y-axis direction, notches that appear rectangular when viewed from the Y-axis direction are formed at the upper and lower parts of both ends in the X-axis direction. Alternatively, each notch can be described as forming a recess that indents a portion of the reference long cylindrical shape. Of the multiple notches, a pair located at the upper part of the container 100 are designated as first recesses 101, and a pair of notches located at the lower part of the container 100 are designated as second recesses 102. A terminal 300 is disposed in the first recess 101, and a gas discharge valve 800 is disposed in the second recess 102 (see reference). Figure 3 as well as Figure 4 Specifically, a gas discharge valve 800 is disposed on the surfaces (first lower surface 114 and second lower surface 124: described later) facing the negative Z-axis direction in the second recess 102. The gas discharge valve 800 is a safety valve that releases pressure in case of excessive pressure rise inside the container 100.

[0074] Container 100 comprises a container body 160 and a pair of lids 170, forming a cylindrical shape that is elongated in the X-axis direction by assembling the container body 160 and each lid 170. The container body 160 comprises a pair of flat wall portions 131 and a pair of curved wall portions 141, 151, forming a cylindrical shape that is elongated in the X-axis direction and extends through the pair of flat wall portions 131 and the pair of curved wall portions 141, 151. Each lid 170 is a plate-like member that closes each end of the container body 160 in the X-axis direction, and is included in the wall portion of the container 100. The lid 170 located in the negative X-axis direction closes the end of the container body 160 in the negative X-axis direction, and the lid 170 located in the positive X-axis direction closes the end of the container body 160 in the positive X-axis direction. Each cover 170 is formed by bending a flattened metal sheet to match the shape of the opposite container body 160 at its X-axis end.

[0075] With this structure, the container 100 is configured such that after the electrode body 700 and the like are housed inside the container body 160, the container body 160 is joined to the lid 170 by welding or the like, thereby sealing the interior. The material of the container 100 (the container body 160 and the lid 170) is not particularly limited, but weldable metals such as stainless steel, aluminum, aluminum alloy, iron, and electroplated steel sheet are preferred.

[0076] Illustrations are omitted here, but an electrolyte injection section is formed on the container body 160 or the cover 170. The electrolyte injection section is a part used to inject electrolyte into the inside of the container 100 during the manufacture of the energy storage element 10.

[0077] The container body 160 includes a pair of flat wall portions 131 and a pair of curved wall portions 141 and 151. Each of the curved wall portions 141 is an elongated wall portion in the X-axis direction and faces the curved portion 711 of the electrode body 700. The inner surface of each curved wall portion 141 is curved along the curved portion 711 of the electrode body 700. Specifically, the inner surface of the curved wall portion 141 in the positive Z-axis direction is concave in the positive Z-axis direction, and the inner surface of the curved wall portion 151 in the negative Z-axis direction is concave in the negative Z-axis direction. In this embodiment, the outer surfaces of the curved wall portions 141 and 151 are also curved, with the curved wall portion 141 formed as a curved plate protruding in the positive Z-axis direction and the curved wall portion 151 formed as a curved plate protruding in the negative Z-axis direction. Each of the flat wall portions 131 is an elongated wall portion in the X-axis direction and faces the flat portion 712 of the electrode body in the Y-axis direction. Each flat wall portion 131 is formed as a flat plate parallel to the XZ plane, and the inner surface of the flat wall portion 131 is arranged along the flat portion 712 of the electrode body 700. In this embodiment, the end of each flat wall portion 131 has a portion that protrudes further in the X-axis direction than other portions, so that the end of each flat wall portion 131 is joined to the end of the bent cover 170 without gap. Specifically, the central portion in the Z-axis direction of the cover 170 is bent into a shape that protrudes in the X-axis direction, so the central portion in the Z-axis direction of the end of the flat wall portion 131 protrudes further in the X-axis direction than other portions of the end of the flat wall portion 131.

[0078] In the container body 160, the outer surface of each flat wall portion 131 has a long side surface 130, the outer surface of each curved wall portion 141 has a top surface 140, and the outer surface of each curved wall portion 151 has a bottom surface 150. The long side surface 130 is a long strip in the X-axis direction and parallel to the XZ plane; a pair of long side surfaces 130 face away from each other in the Y-axis direction. The top surface 140 is a long strip in the X-axis direction and curves along the curved portion 711 of the electrode body 700 in the positive Z-axis direction, located further along the positive Z-axis direction than the long side surface 130. The bottom surface 150 is a long strip in the X-axis direction and curves along the curved portion 711 of the electrode body 700 in the negative Z-axis direction, located further along the negative Z-axis direction than the long side surface 130.

[0079] The outer surface of one of the pair of covers 170 in the positive X-axis direction has a first side surface portion 110. The first side surface portion 110 includes a first upper side surface 111, a first upper surface 112, a first middle side surface 113, a first lower surface 114, and a first lower side surface 115. The first upper side surface 111 and the first lower side surface 115 are surfaces parallel to the YZ plane. The first upper side surface 111 is continuous with the first upper surface 112 and is the surface of the outer surface of the cover 170 in the positive X-axis direction closest to the positive Z-axis direction. The first lower side surface 115 is continuous with the first lower surface 114 and is the surface of the outer surface of the cover 170 in the positive X-axis direction closest to the negative Z-axis direction. The first intermediate side surface 113 is a surface continuous with the first upper surface 112 and the first lower surface 114, and when viewed from the X-axis direction, it is positioned between the first upper side surface 111 and the first lower side surface 115 in the Z-axis direction. The outer surface of one of the pair of cover bodies 170 in the negative X-axis direction has a second side surface portion 120. The second side surface portion 120 includes a second upper side surface 121, a second upper surface 122, a second intermediate side surface 123, a second lower surface 124, and a second lower side surface 125. The structure of these outer surfaces of the cover body 170 in the negative X-axis direction is the same as the structure of the outer surface of the cover body 170 in the positive X-axis direction, therefore, description is omitted.

[0080] Terminal 300 is a terminal (positive and negative terminals) electrically connected to electrode body 700 via current collector 600. In other words, terminal 300 is a metallic component used to conduct electricity stored in electrode body 700 to the external space of energy storage element 10, or to introduce electricity into the internal space of energy storage element 10 for storing electricity in electrode body 700. The material of terminal 300 is not particularly limited; 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, welding, etc., and is mounted on cover 170.

[0081] In this embodiment, the terminal 300 includes a terminal body portion 330 and a shaft portion 340 protruding from the terminal body portion 330. The terminal body portion 330 is a portion that protrudes outward from the terminal mounting surface in the container 100. Here, the terminal mounting surface is the surface in each first recess 101 facing the positive Z-axis direction, the terminal mounting surface in the positive X-axis direction is the first upper surface 112, and the terminal mounting surface in the negative X-axis direction is the second upper surface 122. In this embodiment, the terminal body portion 330 protrudes outward from the terminal mounting surface in the positive Z-axis direction towards the outside of the container 100. In each cover 170, through holes 112a and 122a are formed in the wall portion including each terminal mounting surface (in this embodiment, the first upper surface 112 and the second upper surface 122) for the shaft portion 340 to pass through. The shaft portion 340 is riveted through the wall portion including the terminal mounting surface (in this embodiment, the first upper surface 112 and the second upper surface 122), the outer gasket 400, the inner gasket 500, and the current collector 600, thereby connecting (joining) the terminal 300 to the current collector 600. Each cover 170 may also be bent into a shape that matches the end of the container body 160 in the X-axis direction during or after this connection.

[0082] One current collector 600 is disposed at each end of the electrode body 700 along the X-axis direction. The current collector 600 is a conductive member (positive current collector and negative current collector) that connects (joins) the electrode body 700 and the terminal 300 to electrically connect them. The current collector 600 integrally includes a first joint portion 630 and a second joint portion 640. Specifically, the first joint portion 630 of the current collector 600 is connected (joined) to the electrode tab portion 720 of the electrode body 700 (described later) by welding or riveting, and the second joint portion 640 of the current collector 600 is connected (joined) to the terminal 300 by riveting or welding. The first joint portion 630 and the second joint portion 640 are both flat plate-shaped portions, formed by bending a metal plate. The material of the current collector 600 is not particularly limited; the positive current collector is formed of a conductive member such as aluminum or an aluminum alloy, and the negative current collector is formed of a conductive member such as copper or a copper alloy.

[0083] An outer gasket 400 is disposed between the cover 170 and the terminal 300 of the container 100, serving as an insulator between the cover 170 and the terminal 300 and sealing the interior of the container 100. In this embodiment, the outer gasket 400 is a plate-shaped and rectangular insulating component. An inner gasket 500 is disposed between the cover 170 and the current collector 600, serving as an insulator between the cover 170 and the current collector 600 and sealing the interior of the container 100. In this embodiment, both the outer gasket 400 and the inner gasket 500 are plate-shaped and rectangular insulating components. The materials of the outer gasket 400 and the inner gasket 500 can also be electrically insulating resins such as polypropylene (PP), polyethylene (PE), polystyrene (PS), ABS resin, or composite materials thereof.

[0084] The electrode body 700 is an energy storage element (power generation element) formed by winding an electrode plate. The electrode body 700 has a long cylindrical shape extending along the X-axis. The length of the electrode body 700 in the Y-axis direction is shorter than its lengths in the X-axis and Z-axis directions; therefore, the electrode body 700 can be described as having a flat shape. The length of the electrode body 700 in the X-axis direction is 300 mm or more, specifically approximately 500 mm to 1500 mm. The length of the electrode body 700 in the X-axis direction is longer than its length in the Z-axis direction, and the length of the electrode body 700 in the X-axis direction is more than three times its length in the Z-axis direction. The electrode body 700 has a main body 710 and a plurality of tabs 720 protruding from the main body 710, which, as described above, are connected (joined) to the current collector 600.

[0085] In this embodiment, a plurality of electrode tabs 720 protrude from each of the two end faces of the main body 710 in the X-axis direction. A positive electrode tab 721 is provided on the end face (one end face) in the positive X-axis direction of the main body 710, and a negative electrode tab 722 is provided on the end face (the other end face) in the negative X-axis direction of the main body 710.

[0086] Such an energy storage element 10 is manufactured by the following method. First, a container body 160 is formed by extrusion molding or by rolling up metal sheets and welding the ends together in the Z-axis direction. The container body 160 can also be formed by welding together multiple segments divided in the XY plane. Next, an electrode body 700 is inserted into the container body 160. After insertion, the current collector 600 is connected to the positive and negative electrode tabs 720. Next, after assembling the outer gasket 400, inner gasket 500, cover 170 and terminal 300 to each current collector 600, each cover 170 is welded to both ends of the container body 160. Then, electrolyte is injected into the container 100 from the injection port, and the injection port is sealed.

[0087] [Explanation of the structure of the electrode]

[0088] Figure 5 This is a perspective view showing the structure of the electrode body 700 according to the embodiment. Specifically, Figure 5 This indicates the state in which the wound portion of the electrode plate in the electrode body 700 is unwound. For example... Figure 5 As shown, the electrode body 700 includes a positive electrode plate 740, a negative electrode plate 750, and separators 761 and 762.

[0089] The positive electrode plate 740 is an electrode plate (electrode plate) on both sides of a positive electrode current collector foil 741, which is a strip-shaped metal foil, to which a positive electrode active material layer 742 is disposed. The positive electrode current collector foil 741 is made of aluminum or an aluminum alloy, etc. The negative electrode plate 750 is an electrode plate (electrode plate) on both sides of a negative electrode current collector foil 751, which is a strip-shaped metal foil, to which a negative electrode active material layer 752 is disposed. The negative electrode current collector foil 751 is made of copper or a copper alloy, etc. 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 can be made of known materials as long as they are capable of encapsulating and releasing lithium ions.

[0090] 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, and 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.) with an α-NaFeO2 type crystal structure. As negative electrode active materials, examples include lithium metal, alloys capable of encapsulating / releasing lithium, carbon materials (graphite, difficult-to-graphitize carbon, easily-graphitize carbon, low-temperature sintered carbon, amorphous carbon, etc.), and silicon oxides.

[0091] Here, when the positive electrode active material is an active material with an α-NaFeO2 type crystal structure but contains Ni, setting the mass ratio of Ni in the positive electrode active material to the mass of the transition metal to be 50% or more is preferred in terms of improving the energy density of the electrode body 700. The positive electrode active material layer may, as needed, contain other positive electrode active materials besides the aforementioned lithium transition metal composite oxide, conductive agents, binders, thickeners, fillers, or any other components.

[0092] The separators 761 and 762 are microporous sheets made of resin. Known materials can be appropriately used as the materials for separators 761 and 762, as long as they do not impair the performance of the energy storage element 10. Synthetic resin microporous membranes made of polyolefin resins such as woven fabrics, nonwoven fabrics, and polyethylene, which are insoluble in organic solvents, can also be used as separators 761 and 762.

[0093] The electrode body 700 is formed by winding a positive electrode plate 740, a negative electrode plate 750, and separators 761 and 762. The electrode body 700 is formed by stacking and winding the negative electrode plate 750, separator 761, positive electrode plate 740, and separator 762 in this order. In this embodiment, the positive electrode plate 740, negative electrode plate 750, and separators 761 and 762 are wound around a winding axis L extending in the X-axis direction, thereby forming a wound-type electrode body 700. The winding axis L is an imaginary axis that serves as the central axis when winding the positive electrode plate 740, negative electrode plate 750, and separators 761 and 762. In this embodiment, the winding axis is a straight line passing through the center of the electrode body 700 and parallel to the X-axis direction.

[0094] On the positive X-axis end edge of the positive electrode plate 740, a plurality of outwardly protruding tabs 743 are arranged at intervals. Similarly, on the negative X-axis end edge of the negative electrode plate 750, a plurality of outwardly protruding tabs 753 are arranged at intervals. Each of the plurality of protruding tabs 743 is a portion of the positive electrode current collector foil 741 exposed where no positive electrode active material layer is disposed (non-formed portion of the positive electrode active material layer). Each of the plurality of protruding tabs 753 is a portion of the negative electrode current collector foil 751 exposed where no negative electrode active material layer is disposed (non-formed portion of the negative electrode active material layer). Figure 5 In the diagram, the non-forming part of the active material layer (non-forming part of the positive electrode active material layer and non-forming part of the negative electrode active material layer) is represented by a slash.

[0095] If the positive electrode plate 740, the negative electrode plate 750, and the separators 761 and 762 are wound, then on the end face (one end face) of the main body 710 in the positive X-axis direction, the multiple protruding pieces 743 of the positive electrode plate 740 almost overlap, and on the end face (the other end face) in the negative X-axis direction, the multiple protruding pieces 753 of the negative electrode plate 750 almost overlap. The overlapping portion of the multiple protruding pieces 743 in the positive electrode plate 740 is the positive electrode tab 721. In other words, the positive electrode tab 721 is the portion formed by the stacking of multiple pieces (protruding pieces 743) of the same polarity electrode plate (positive electrode plate 740) among the multiple electrodes (positive electrode plate 740 and negative electrode plate 750). Hereinafter, the descriptions of overlapping and coincidence are not limited to a single integral stack in a strict sense. Overlapping and coincidence include a situation where there is a deviation (misalignment) overlap in a direction perpendicular to the direction of overlap.

[0096] Similarly, the overlapping portion of the multiple protruding pieces 753 in the negative electrode plate 750 is the negative electrode tab 722. In other words, the negative electrode tab 722 is the portion formed by the stacking of multiple pieces (protruding pieces 753) of the same polarity electrode plate (negative electrode plate 750) among the multiple electrode plates (positive electrode plate 740 and negative electrode plate 750).

[0097] Thus, the electrode body 700 includes a main body portion 710 constituting the main body of the electrode body 700 and electrode tabs 720 (positive electrode tab 721 and negative electrode tab 722) protruding from each end face in the X-axis direction of the main body portion 710. In other words, the electrode body 700 has a pair of electrode tabs composed of the positive electrode tab 721 and the negative electrode tab 722.

[0098] The main body 710 is an elongated cylindrical portion formed by winding the portion of the positive electrode plate 740 in which the positive electrode active material layer 742 is disposed (formed, coated), the portion of the negative electrode plate 750 in which the negative electrode active material layer 752 is disposed (formed, coated), and the separators 761 and 762. The region in the main body 710 where at least one of the positive electrode active material layer 742 and the negative electrode active material layer 752 is stacked is called the active material layer forming portion. The outer surface of the main body 710 has curved portions 711 at both ends in the Z-axis direction and flat portions 712 at both ends in the Y-axis direction. In other words, the outer surface of the main body 710 has a pair of curved portions 711 and a pair of flat portions 712. Each flat portion 712 of the pair of flat portions 712 is located between the pair of curved portions 711 in the Z-axis direction, and is generally flat. Alternatively, the pair of curved portions 711 can be described as being positioned to sandwich each flat portion 712 in the Z-axis direction.

[0099] The curved portion 711 is a part that extends along the X-axis and protrudes towards the Z-axis. Viewed from the X-axis direction, the curved portion 711 is curved into a semi-circular arc shape. The curved portion 711 located in the positive Z-axis direction is opposite to the curved wall portion 141 of the container body 160 in the Z-axis direction, and the curved portion 711 located in the negative Z-axis direction is opposite to the curved wall portion 151 of the container body 160 in the Z-axis direction. In other words, the curved portion 711 is opposite to the curved wall portions 141 and 151 in the Z-axis direction.

[0100] The flat portion 712 is a flat area parallel to the XZ plane that extends along the X-axis and connects the ends of a pair of curved portions 711 to each other. The flat portion 712 is a surface perpendicular to the Y-axis direction. Each flat portion 712 is arranged opposite to each flat wall portion 131 of the container body 160. In the portion of the electrode body 700 sandwiched by each flat portion 712, multiple coiled electrode plates and separators (positive electrode plate 740 and negative electrode plate 750, separators 761, 762) are stacked in the Y-axis direction. Here, the main stacking direction of the multiple electrode plates is defined as the Y-axis direction.

[0101] The bending shape of the curved portion 711 when viewed from the X-axis direction is not limited to a semi-circular arc shape, but can also be a part of an ellipse, or a polygon, etc. The flat portion 712 is not limited to the outer surface of the electrode body 700 perpendicular to the Y-axis direction being completely flat, but the outer surface can also be slightly concave or slightly bulging.

[0102] [Retention Unit]

[0103] Figure 6 This is an explanatory diagram showing the holding unit 20, the housing 2, and the energy storage element 10 involved in the embodiment. Figure 6 In the sectional view, only shell 2 is shown. Figure 6 As shown, the retaining unit 20 is composed of a plurality of retaining members 21 arranged along the Y-axis.

[0104] The retaining member 21 is a member that is alternately arranged with the energy storage element 10 in the Y-axis direction and holds the energy storage element 10, and is responsible for insulation and / or heat insulation between the energy storage elements 10 and other members. In this embodiment, the retaining member 21 is configured to directly face at least a portion of the flat wall portion 131 and the curved wall portion 141 of the container 100 and overlap with the region of the active material layer forming portion in the electrode body 700 (see reference). Figure 2 , Figure 4 The retaining member 21 is an insulating plate-shaped member that is arranged adjacent to the energy storage element 10 in the positive or negative Y-axis direction and insulates the energy storage elements 10 from each other or from the housing 2. The retaining member 21 may be formed of insulating members such as PC, PP, PE, PS, ABS resin, or composite materials thereof, or it may be formed of a metal member with an insulating surface.

[0105] From a cooling perspective, each retaining member 21 can also be made of a material with high thermal conductivity. Each retaining member 21 can also be made of an insulating material with higher thermal conductivity than polypropylene. Alternatively, each retaining member 21 can be primarily formed of metal, with its surface covered by an insulating material. To avoid thermal interference with adjacent energy storage elements, each retaining member 21 can also be made of a heat-insulating material. Examples of heat-insulating materials include mica and other heat-insulating components.

[0106] The flat surface 211 and curved surfaces 212, 213 of the intermediate spacer 210 facing the negative Y-axis direction coincide with and contact the surface of the energy storage element 10 facing the positive Y-axis direction, which is adjacent to the intermediate spacer 210 in the negative Y-axis direction. Specifically, the outer surfaces of the flat wall portion 131, the curved wall portion 141, and the curved wall portion 151 of the container 100 of the energy storage element 10, which is adjacent to the intermediate spacer 210 in the negative Y-axis direction, are in surface contact with the flat surface 211 and curved surfaces 212, 213 of the intermediate spacer 210 facing the negative Y-axis direction. In this embodiment, the curved surface 212 contacts the outer surface of the curved wall portion 141 at the position closest to the positive Z-axis direction (the apex of the outer surface of the curved wall portion 141), but it is also possible that a portion of the outer surface of the curved wall portion 141 does not oppose or contact the curved surface 212. Similarly, the curved surface 213 contacts the outer surface of the curved wall portion 151 at the position closest to the negative Z-axis (the vertex of the outer surface of the curved wall portion 151), but a portion of the outer surface of the curved wall portion 151 may not be opposite to or in contact with the curved surface 212.

[0107] Similarly, the flat surface 211 and curved surfaces 212, 213 of the intermediate spacer 210 facing the positive Y-axis coincide with the surface of the energy storage element 10 adjacent to the intermediate spacer 210 in the positive Y-axis direction facing the negative Y-axis direction. Specifically, the outer surfaces of the flat wall portion 131, curved wall portion 141, and curved wall portion 151 of the container 100 of the energy storage element 10 adjacent to the intermediate spacer 210 in the positive Y-axis direction are in surface contact with the flat surface 211 and curved surfaces 212, 213 of the intermediate spacer 210. In this embodiment, the curved surface 212 contacts the outer surface of the curved wall portion 141 at the position closest to the positive Z-axis (the apex of the outer surface of the curved wall portion 141), but it is also possible that a portion of the outer surface of the curved wall portion 141 does not oppose or contact the curved surface 212. Similarly, the curved surface 213 contacts the outer surface of the curved wall portion 151 at the position closest to the negative Z-axis (the vertex of the outer surface of the curved wall portion 151), but a portion of the outer surface of the curved wall portion 151 may not be opposite to or in contact with the curved surface 212.

[0108] In the end spacer 220 disposed in the negative Y-axis direction, the end face in the negative Y-axis direction is formed as a flat surface along the inner surface of the housing body 30, and the end face in the positive Y-axis direction is formed as a shape that is recessed in the negative Y-axis direction along the outline of the adjacent energy storage element 10. The flat surface 221 and the curved surfaces 222, 223 of the end spacer 220 coincide with and contact the surface of the adjacent energy storage element 10 in the positive Y-axis direction facing the negative Y-axis direction.

[0109] Similarly, in the end spacer 220 disposed in the positive Y-axis direction, the end face in the positive Y-axis direction is formed as a flat surface along the inner surface of the housing body 30, and the end face in the negative Y-axis direction is formed as a shape that is recessed in the positive Y-axis direction along the outline of the adjacent energy storage element 10. The flat surface 221 and the curved surfaces 222, 223 of the end spacer 220 coincide with and contact the surface of the adjacent energy storage element 10 in the negative Y-axis direction facing the positive Y-axis direction.

[0110] In this embodiment, the inner surface of the flat wall portion 131 of the container 100 contacts the flat portion 712 of the electrode body 700, and the inner surface of the curved wall portion 141 contacts the curved portion 711 of the electrode body 700, thereby suppressing and limiting the expansion of the curved portion 711. This suppresses damage to the curved portion 711 and the boundary between the curved portion 711 and the flat portion 712.

[0111] Especially Figure 6 In this configuration, the holding unit 20, which holds each energy storage element 10, presses each energy storage element 10 in the Y-axis and Z-axis directions. Here, at the BOL (Beginning of Life) state of the energy storage element 10, the reaction force in the Y-axis direction and the reaction force in the Z-axis direction exerted by the holding unit 20 on the energy storage element 10 are 1 kN or more and 5 kN or less.

[0112] In the Y-axis and Z-axis directions, which are the compression directions, the wall thickness of the end spacer 220 and the wall thickness of the intermediate spacer 210 are greater than the wall thickness of the container 100. Furthermore, the strength of the retaining unit 20 is greater than the strength of the container 100. The retaining unit 20 has sufficient strength to compress the electrode body 700, and its inner surface has curved surfaces 212 and 222 that largely oppose the curved wall portion 141 of the container 100, and a flat surface 221 that largely opposes the flat wall portion 131 of the container 100. Since the container 100 is directly located between the retaining unit 20 and the electrode body 700, the pressure from the retaining unit 20 is transmitted to the electrode body 700 via the container 100 through the outer surface of the container 100. Therefore, a compressive force exceeding the strength of the container 100 can be applied to the electrode body 700, suppressing deformation of the container 100 caused by the expansion of the electrode body 700. In other words, it is possible to suppress the expansion of the electrode body 700 beyond the size of the container 100. As a result, it is possible to suppress the tension generated at the boundary between the flat portion 712 and the curved portion 711.

[0113] In particular, by contacting the inner surface of the curved wall portion 141 with the curved portion 711 of the electrode body 700, stress is applied to the curved portion 711 from the curved wall portion 141, which can more reliably suppress the expansion of the curved portion 711. By eliminating the possibility of expansion of the curved portion 711 within the container 100, the dimensional changes of the electrode body 700 can be limited.

[0114] Furthermore, the outer surface of the curved wall portion 141 comes into surface contact with the curved surfaces 212 and 222 of the holding unit 20, thereby applying stress to the curved wall portion 141 from the curved surfaces 212 and 222. Therefore, even if the curved wall portion 141 expands due to the electrode body 700, the expansion can be more reliably suppressed by the curved surfaces 212 and 222. By utilizing the curved surfaces 212 and 222 of the holding unit 20, the possibility of expansion of the curved wall portion 141 of the container 100 can be eliminated, and the dimensional changes of the container 100 can be limited.

[0115] Here, the BOL (Balance of Operation) of the energy storage element 10 includes the period immediately after manufacture or at the time of manufacture. Immediately after manufacture, it also includes the period during which the charge-discharge cycles of the energy storage element 10, initially charged after manufacture, converge within a given number of cycles. The given number is the number of times the main body 710 of the electrode body 700 expands and the outer surface of the main body 710 as a whole comes into contact with the inner surface of the container 100. The given number is preferably 10 times, more preferably 5 times, and even more preferably 3 times.

[0116] After the holding unit 20 of each energy storage element 10 is housed in the housing 2, it is pressed by the housing 2 in the Y-axis and Z-axis directions. At this time, as Figure 6 As shown, in the Y-axis and Z-axis directions, the outer surface of the retaining unit 20 is in surface contact with the inner surface of the housing 2. Therefore, each energy storage element 10 is subjected not only to the pressure (constraint force) of the retaining unit 20, but also to the pressure (constraint force) from the housing 2.

[0117] It is possible to determine whether the energy storage element 10 held by the holding unit 20 is compressed by the holding unit 20 by detecting the deformation of the energy storage element 10 when the holding unit 20 and each energy storage element 10 are disassembled. Specifically, the size of the energy storage element 10 before disassembly and the size of the energy storage element 10 after disassembly are measured. If the size of the energy storage element 10 after disassembly is larger than the size of the energy storage element 10 before disassembly, it can be determined that the energy storage element 10 was compressed before disassembly. The bulging of the energy storage element 10 can also be determined by the shape changes before and after the compression is released, such as the shape changes caused by the energy storage element 10 embedding into the holding unit 20 after the compression is released, based on CT imaging.

[0118] [Explanation of Effects]

[0119] As described above, in the energy storage element 10 according to an embodiment of the present invention, the container 100 has a curved wall portion 141 opposite to the curved portion 711 of the electrode body 700, and the inner surface of the curved wall portion 141 has a curved shape along the curved portion 711 of the electrode body 700. Therefore, the space generated between the curved portion 711 of the electrode body 700 and the curved wall portion 141 of the container 100 is smaller than the space generated between the curved portion of the electrode body and the inner surface of the container in the case of a square container, and the expansion of the curved portion 711 of the electrode body 700 relative to the expansion of the flat portion 712 of the electrode body 700 can be suppressed. Furthermore, curved surfaces 212 and 222 with a curved shape along the outer surface of the curved wall portion 141 of the container 100 are provided on the inner surface of the holding unit 20, so that the electrode body 700 is compressed when the container 100 is pressed by the holding unit 20. Therefore, the pressure from the holding unit 20 is transmitted to the electrode body 700 via the container 100, and a compressive force exceeding the strength of the container 100 can be applied to the electrode body 700, which can suppress the deformation of the container 100 caused by the expansion of the electrode body 700. As a result, the tension generated at the boundary between the flat portion 712 and the curved portion 711 can be suppressed, and damage to the electrode body 700 can be suppressed.

[0120] The inner surface of the curved wall portion 141 of the container 100 presses against the curved portion 711 of the electrode body 700, and the inner surface of the flat wall portion 131 of the container 100 presses against the flat portion 712 of the electrode body 700. This creates a state where both the curved portion 711 and the flat portion 712 of the electrode body 700 are compressed, thus more reliably suppressing the situation where the expansion of the curved portion 711 of the electrode body 700 is relatively easier to occur compared to the expansion of the flat portion 712. As a result, the tension generated at the boundary between the flat portion 712 and the curved portion 711 can be further suppressed, and damage to the electrode body 700 can be further suppressed.

[0121] Immediately after manufacturing, consider the case where the outer surface of the flat portion 712 of the electrode body 700 does not contact the inner surface of the flat wall portion 131 of the container 100, or the case where the outer surface of the curved portion 711 of the electrode body 700 does not contact the inner surface of the curved wall portion 141 of the container 100. Even in these cases, if the electrode body 700 expands due to the use of the energy storage element 10 after sale, and the flat wall portion 131 of the container 100 presses against the flat portion 712 of the electrode body 700, and the curved wall portion 141 of the container 100 presses against the curved portion 711 of the electrode body 700, this is also included in the structure of this application.

[0122] When the flat portion 131 of the container 100 presses against the flat portion 712 of the electrode body 700, and the curved portion 141 of the container 100 presses against the curved portion 711 of the electrode body 700, the curved surfaces 212 and 213 of the holding unit 20 press against the outer surface of the curved wall portion 141 of the container 100. That is, the pressure from the holding unit 20 is transmitted to the curved portion 711 of the electrode body 700 via the curved surfaces 212 and 213 of the holding unit 20 and the curved wall portion 141 of the container 100. As a result, even with a large compressive force exceeding the strength of the curved wall portion 141 of the container 100 applied to the curved portion 711 of the electrode body 700, deformation of the container 100 caused by the expansion of the curved portion 711 of the electrode body 700 can be suppressed.

[0123] Because the inner surface of the retaining unit 20 presses against the outer surface of the flat wall portion 131 of the container 100, the expansion of the flat wall portion 131 of the container 100 can be suppressed more reliably. Furthermore, by applying pressure to the flat portion 712 of the electrode body 700 via the flat wall portion 131 of the container 100 and to the curved portion 711 of the electrode body 700 via the curved wall portion 141 of the container 100, deformation is suppressed throughout the electrode body 700. As a result, adverse conditions related to capacity reduction, such as deformation of the electrode body 700, which occur at a stage earlier than damage to the electrode body 700, can be suppressed more reliably.

[0124] Each retaining member 21 integrally provides a flat surface 211, 221 for pressing the flat wall portion 131 and a curved surface 212, 222 for pressing the curved wall portion 141. Therefore, the retaining member 21 can suppress both the expansion of the flat wall portion 131 and the expansion of the curved wall portion 141 in the container 100, and the electrode body 700 can be pressed with a simple structure.

[0125] By holding the outer surface of the retaining member 21 under pressure from the housing 2 (external member), the curved surfaces 212 and 222 of the retaining member 21 press against the outer surface of the curved wall portion 141 of the container 100. At this time, the curved surfaces 212 and 222 of the inner surface of the retaining member 21 are also pressing against the curved wall portion 141 of the container 100, applying a large pressure force to the curved wall portion 141 of the container 100, which is composed of the pressure force from the housing 2 and the pressure force from the retaining member 21. Furthermore, the deformation of the container 100 caused by the expansion of the curved portion 711 of the electrode body 700 can be suppressed more reliably. Since the electrode body 700 is also under pressure from the container 100, the expansion of the electrode body 700 beyond the internal dimensions of the container 100 can be suppressed more effectively. In addition, when the bent portion 711 of the electrode body 700 is pressed from the bent wall portion 141 of the container 100 and the flat portion 712 of the electrode body 700 is pressed from the flat wall portion 131 of the container 100, the expansion of both the bent portion 711 and the flat portion 712 of the electrode body 700 can be suppressed to prevent the tensile stress between them from becoming greater than the current size, thereby further suppressing the foil breakage of the electrode body 700.

[0126] Here, the flat wall portion 131 of the container 100 is preferably directly located between the flat surface 211 of the holding unit 20 and the flat portion 712 of the electrode body 700, and is in surface contact. The curved wall portion 141 of the container 100 is preferably directly located between the curved surfaces 212 and 222 of the holding unit 20 and the curved portion 711 of the electrode body 700, and is in surface contact. Thus, the compressive force from the holding unit 20 is transmitted to the electrode body 700 through the walls of the container 100 (flat wall portion 131 and curved wall portion 141), and the electrode body 700 can be compressed.

[0127] [Comparison of this invention with prior art]

[0128] Figure 7 This is a cross-sectional view of the prior art energy storage element 10y (Comparative Example 1), cut along a plane parallel to the YZ plane. Specifically, the energy storage element 10y of Comparative Example 1 is an energy storage element 10y that houses a flat, wound electrode body 700y within a square container 100y. Figure 7The diagram shows an example of the internal structure of a storage element 10y in which the flat portion 712y of the electrode body contacts the inner surface of the container 100y when the electrode body expands. In conventional structures, even when the flat portion 712y of the electrode body contacts the inner surface of the container 100y, sometimes the curved portion 711y of the electrode body does not contact the inner surface of the container 100y. In such cases, if the expansion of the electrode body 700y progresses, in the region of the flat portion 712y of the electrode body, the expansion initially proceeds mainly in the thickness direction (Y-axis direction) of the electrode plate, but gradually extends towards the length direction (Z-axis direction) of the electrode plate. Moreover, towards the end of the lifespan of the storage element 10y, the expansion in the thickness direction (Y-axis direction) of the electrode body 700y is compressed by the inner surface of the container 100y, and the friction between the inner surface of the storage element 10y and the outer surface of the flat portion 712y of the electrode body increases, preventing further extension towards the length direction (Z-axis direction) of the electrode plate. On the other hand, even at the end of the lifespan of the energy storage element 10y, residual space remains between the inner surfaces of the electrode body 700y and the container 100y in the bent portion 711y of the electrode body, and the extension of the electrode plate in the long side direction (Y-axis direction, Z-axis direction) continues. Therefore, in the region at the boundary between the flat portion 712y of the electrode body 700y and the bent portion 711y of the electrode body, strong tensile stress is generated in the electrode plate, which may sometimes lead to the breakage of the electrode plate in the worst case.

[0129] Figure 8 This is a cross-sectional view of a prior art energy storage element 10z (Comparative Example 2), which has a design altered by cutting off a portion of the energy storage element of Comparative Example 1 with a plane parallel to the YZ plane. Figure 8 The energy storage element 10z of Comparative Example 2 differs from the energy storage element 10y of Comparative Example 1 in that, when the electrode body 700z expands, the upper part (end in the positive Z-axis direction) of the bent portion 711z of the electrode body and the flat portion 712z of the electrode body contact the inner surface of the container 100z together. The other structures of the energy storage element 10z in Comparative Example 2 are the same as those of the energy storage element 10y of Comparative Example 1. In the case of the energy storage element 10y of Comparative Example 1, if the expansion ratio of the electrode body 700y... Figure 7As the situation progresses, the flat portion 712y of the electrode body 700y is pressed by the inner surface of the container 100y, preventing it from extending along the length direction (Z-axis direction) of the electrode plate. On the other hand, the curved portion 711y of the electrode body retains remaining space, thus allowing the electrode plate to continue extending along its length direction (Y-axis direction, Z-axis direction). In contrast, in the energy storage element 10z of Comparative Example 2, the upper part of the curved portion 711z (the Z-axis end of the curved portion) is also pressed by the inner surface of the container 100z, but remaining space exists between the curved portion 711z and the inner surface of the container 100z, except for the upper part of the curved portion 711z. Therefore, the electrode body 700z deforms, causing uneven inter-electrode distances and potentially leading to lithium deposition. This can result in battery capacity degradation.

[0130] Figure 9 This illustrates an example of a power storage device 1 in which the curved surface 222 of the holding unit 20 of the present invention presses against the outer surface of the curved wall portion 141 of the container 100 of the power storage element 10. An electrode body 700 having a curved portion 711 and a flat portion 712 is housed in a container 100 arranged along the outer surface of the electrode body 700, and the holding unit 20 is further arranged along the outer surface of the container 100. Figure 9 In this structure, the holding unit 20, along with the intermediate spacer 210 and end spacer 220 of the two holding members, compresses the energy storage element 10. Thus, the holding unit 20 forms a container 100 that compresses the energy storage element 10, thereby compressing the electrode body 700. In this invention, as the electrode body 700 expands, the expansion of the electrode body 700 is uniformly compressed throughout the entire container 100 and the entire holding unit 20. Therefore, it is possible to suppress the deformation of the electrode body and the breakage of the electrode caused by tensile stress generated between the curved portion 711 and the flat portion 712, as described above.

[0131] [Explanation of variations]

[0132] Hereinafter, various modifications of the above embodiments will be described. In the following description, the same reference numerals will sometimes be used to refer to parts that are the same as those in the above embodiments or other modifications, and their descriptions will be omitted.

[0133] (Variation Example 1)

[0134] The retaining element 20A involved in Modified Example 1 will be explained. Figure 10 This is an explanatory diagram showing the holding unit 20A, housing 2 and each energy storage element 10 involved in Modification Example 1.

[0135] like Figure 10As shown, the holding unit 20A has a plurality of first holding members 23 and a plurality of second holding members 24 for each energy storage element 10. The first holding members 23 and the second holding members 24 are separate components.

[0136] A pair of first retaining members 23 in the Z-axis direction are positioned in the container 100 that holds the energy storage element 10. The first retaining members 23 have a shape based on a long rectangular parallelepiped shape in the X-axis direction. The lower surface of the first retaining member 23 in the positive Z-axis direction (the surface facing the negative Z-axis direction) is recessed in the positive Z-axis direction along the shape of the energy storage element 10. This recessed portion is deepest at the center in the Y-axis direction of the lower surface of the first retaining member 23, appearing U-shaped when viewed from the X-axis direction. Furthermore, the recessed portion forms a curved shape along the outer surface of the curved wall portion 141. In the modified example 1, since the thickness of the curved wall portion 141 is constant, the recessed portion also forms a curved shape along the inner surface of the curved wall portion 141. The recessed portion includes a curved surface 231, which is in surface contact with the outer surface of the curved wall portion 141 of the energy storage element 10.

[0137] Similarly, the upper surface (facing the positive Z-axis) of the first retaining member 23 located in the negative Z-axis direction is recessed in the negative Z-axis direction along the outline of the adjacent energy storage element 10. Viewed from the X-axis direction, this recessed portion is U-shaped. The recessed portion forms a curved shape along the outer surface of the curved wall portion 151. In the modified example 1, since the thickness of the curved wall portion 151 is constant, the recessed portion also forms a curved shape along the inner surface of the curved wall portion 151. The recessed portion is a curved surface 231 that is in surface contact with the outer surface of the curved wall portion 151 of the energy storage element 10.

[0138] Multiple second retaining members 24 are arranged alternately with the energy storage element 10 in the Y-axis direction. Each second retaining member 24 comprises a flat plate shape that is elongated in the X-axis direction, parallel to the XZ plane, and flat in the Y-axis direction. The positive Z-axis surface of the second retaining member 24 contacts the lower surface (facing the negative Z-axis) of the first retaining member 23 located further along the positive Z-axis than the second retaining member 24, and the negative Z-axis surface of the second retaining member 24 contacts the upper surface (facing the positive Z-axis) of the first retaining member 23 located further along the negative Z-axis than the second retaining member 24. The surface of each second retaining member 24 that faces the energy storage element 10 in the Y-axis direction is a flat surface 241 that is in surface contact with the outer surface of the flat wall portion 131 of the energy storage element 10.

[0139] As described above, since the first retaining member 23 and the second retaining member 24 are separate, the first retaining member 23 and the second retaining member 24 can be installed separately, making it easier to manufacture the energy storage device 1. Furthermore, the pressure applied from the first retaining member 23 to the opposing direction of the pair of curved portions 711 of the electrode body 700 and the pressure applied from the second retaining member 24 to the direction perpendicular to the flat portion 712 of the electrode body 700 can be adjusted separately. Even if the size of the energy storage element 10 changes due to design or model changes, as long as the shape of the container 100 remains partially the same, either the first retaining member 23 or the second retaining member 24 can be used to reduce manufacturing costs.

[0140] (Variation Example 2)

[0141] The retaining element 20B involved in Modified Example 1 will be explained. Figure 11 This is an explanatory diagram showing the holding unit 20B, housing 2 and each energy storage element 10 involved in Modification Example 1.

[0142] like Figure 11 As shown, the holding unit 20B includes a pair of first holding members 25 and a plurality of second holding members 26. The first holding members 25 and the second holding members 26 are separate, i.e., different components. In this modified example, the first holding member 25 is shown to have a refrigerant path 22 for refrigerant flow, but it can also be a path for the flow of a medium for the purpose of temperature regulation of the energy storage element. In other words, the refrigerant path 22 can also be a path for the flow of a medium for heat preservation or heating of the energy storage element.

[0143] Multiple second retaining members 26 are arranged alternately with the energy storage element 10 in the Y-axis direction. Each second retaining member 26 includes a flat plate shape that is elongated in the X-axis direction and parallel to the XZ plane, and flat in the Y-axis direction. Each surface of the second retaining member 26 facing the Y-axis direction is a planar flat surface 261 that faces and contacts the outer surface of the flat wall portion 131 of the energy storage element 10.

[0144] A pair of first retaining members 25 are arranged in the Z-axis direction at the position of the container 100 holding the energy storage element 10 and a plurality of second retaining members 26. The first retaining members 25 have a rectangular shape based on being elongated in the X-axis direction and flattened in the Z-axis direction. The portion of the first retaining member 25 located in the positive Z-axis direction facing the negative Z-axis direction, which is opposite to each energy storage element 10 in the Z-axis direction, is recessed in the positive Z-axis direction along the shape of the energy storage element 10. The number of these recessed portions is the same as the number of energy storage elements 10. Viewed from the X-axis direction, each recessed portion is U-shaped. The recessed portion is a curved shape along the outer surface of the curved wall portion 141. In this modified example, since the thickness of the curved wall portion 141 is constant, the recessed portion is also a curved shape along the inner surface of the curved wall portion 141. Each recessed portion is a curved surface 251 that is in surface contact with the outer surface of the curved wall portion 141 of the energy storage element 10.

[0145] Similarly, the portion of the first retaining member 25 located in the negative Z-axis direction facing the positive Z-axis direction, which is opposite to each energy storage element 10 in the Z-axis direction, is recessed in the negative Z-axis direction along the shape of the energy storage element 10. The number of these recessed portions is the same as the number of energy storage elements 10. Viewed from the X-axis direction, each recessed portion is U-shaped. The recessed portion is a curved shape along the outer surface of the curved wall portion 141. In this modified example, since the thickness of the curved wall portion 141 is constant, the recessed portion is also a curved shape along the inner surface of the curved wall portion 141. Each recessed portion is a curved surface 251 that is in surface contact with the outer surface of the curved wall portion 141 of the energy storage element 10. Thus, each first retaining member 25 integrally provides a plurality of curved surfaces 251.

[0146] Among the plurality of energy storage elements 10 held by such a holding unit 20B, one energy storage element 10 is an example of a first energy storage element, and the other energy storage elements 10 adjacent to the first energy storage element in the Y-axis direction are examples of second energy storage elements. The electrode body 700 of the first energy storage element is an example of a first electrode body. The flat portion 712 and the curved portion 711 of the first electrode body are examples of a first flat portion and a first curved portion. The container 100 of the first energy storage element is an example of a first container. The flat wall portion 131 and the curved wall portion 141 of the first container are examples of a first flat wall portion and a first curved wall portion. The electrode body 700 of the second energy storage element is an example of a second electrode body. The flat portion 712 and the curved portion 711 of the second electrode body are examples of a second flat portion and a second curved portion. The container 100 of the second energy storage element is an example of a second container. The flat wall portion 131 and the curved wall portion 141 of the second container are examples of the second flat wall portion and the second curved wall portion. Among the multiple curved surfaces 251 of each first retaining member 25, the curved surface 251 opposite to the curved wall portion 141 of the first energy storage element and the curved surface 251 opposite to the curved wall portion 151 of the first energy storage element are examples of the first curved surface, and the curved surface 251 opposite to the curved wall portion 141 of the second energy storage element and the curved surface 251 opposite to the curved wall portion 151 of the second energy storage element are examples of the second curved surface.

[0147] As described above, the plurality of curved surfaces 251 (first curved surface, second curved surface) of the first retaining member 25 face each of the curved wall portions 141, 151 of the plurality of energy storage elements 10 (first energy storage element, second energy storage element), so that the plurality of curved surfaces 251 of the first retaining member 25 can be used to press the plurality of curved wall portions 141, 1510 together. In addition, compared with the case where one first retaining member is arranged for one curved wall portion, the number of first retaining members 25 is reduced, so the assembly of the energy storage device 1 becomes easier.

[0148] Since the first retaining member 25 is made of foamed resin, the curved surface 251 of the first retaining member 25 can be easily formed along the shape of the curved walls 141, 151 of the container 100 during manufacturing. This reduces the number of components associated with the first retaining member 25, making manufacturing easier. Even though the first retaining member 25 is made of foamed resin, it possesses sufficient strength and is formed from a material having an elastic region sufficient to suppress the expansion of the electrode body 700. Polyurethane glass resin is an example of such a foamed resin. Furthermore, the portions of the retaining unit 20B other than the first retaining member 25 can also be formed of foamed resin.

[0149] (Variation Example 3)

[0150] The energy storage element 10c involved in Modification Example 3 will be described. Figure 12This is a perspective view showing the appearance of the energy storage element 10c involved in Modification Example 3. For example... Figure 12 As shown, the container 100c of the energy storage element 10c has a gas discharge valve 800c disposed on the surface of each second recess 102c parallel to the YZ plane. In this case, no gas discharge valve is disposed on the surface of each second recess 102c parallel to the XY plane. The gas discharge valve 800c may also be disposed in only one second recess 102c. The gas discharge valve may also be disposed in at least one first recess.

[0151] (Variation Example 4)

[0152] The energy storage element 10d involved in Modification Example 4 will be described. Figure 13 This is a perspective view showing the appearance of the energy storage element 10d involved in Modification Example 4. For example... Figure 13 As shown, the container 100d of the energy storage element 10d has a pair of first recesses 101d in the positive Z-axis direction, but no recesses in the negative Z-axis direction. At least one of the first recesses 101d in the container 100d is provided with a gas discharge valve 800d on a surface parallel to the YZ plane.

[0153] (Variation Example 5)

[0154] The energy storage element 10e involved in Modification Example 5 will be described. Figure 14 This is a perspective view showing the appearance of the energy storage element 10e involved in Modification Example 5. For example... Figure 14 As shown, the container 100e of the energy storage element 10e does not have a recess, is elongated in the X-axis direction, and has an overall elongated cylindrical shape. Each terminal 300e and each external gasket 400e are disposed on the outer surface of the curved wall portion 141e of the container 100e, and each terminal 300e protrudes from the outer surface of the curved wall portion 141e of the container 100e in the positive Z-axis direction. At least one of a pair of end faces in the X-axis direction of the container 100e is provided with a gas discharge valve 800e.

[0155] As described above, since each terminal 300e protrudes from the outer surface of the curved wall portion 141e of the container 100e, the internal space of the container 100e is difficult to consume. As a result, the electrode body 700 can be maximized, and the energy density can be increased.

[0156] Furthermore, since each terminal 300e protrudes from the outer surface of the curved wall portion 141e of the container 100e, it is easy to connect to the terminals 300e of other energy storage components 10e.

[0157] In the modified embodiment of the energy storage element 10e, no terminals 300e are provided on the surface of the container 100e in the winding axis direction (X-axis direction). Therefore, when the energy storage element 10e is housed in the housing 2, protective members and other components positioned further end-to-end than the energy storage element 10e in the winding axis direction can be simplified and miniaturized. Furthermore, compared to energy storage elements with terminals on the surface in the winding axis direction, the design flexibility of the housing 2 can be increased.

[0158] There is a space located further along the positive Z-axis than terminal 300, which is sandwiched between the walls of holding unit 20 and housing 2. By arranging busbars and the like in this space, the overall energy density of the energy storage device can be improved.

[0159] (Variation Example 6)

[0160] The energy storage element 10f involved in Modification Example 6 will be described. Figure 15 This is a perspective view showing the appearance of the energy storage element 10f involved in Modification Example 6. For example... Figure 15 As shown, the energy storage element 10f has terminals 300 and external gaskets (not shown) arranged on the surfaces of each second recess 102f that are parallel to the XY plane. In other words, one energy storage element 10f has four terminals 300. The gas discharge valve 800f is arranged on the surface of the second recess 102f that is parallel to the YZ plane, but it can also be arranged on the surface of the first recess 101f that is parallel to the YZ plane.

[0161] (Variation Example 7)

[0162] The energy storage element 10g involved in Modification Example 7 will be described. Figure 16 This is a perspective view showing the appearance of the energy storage element 10g according to Modification 7. In the energy storage element 10e according to Modification 5, each terminal 300e and each external pad (not shown) are arranged at both ends of the curved wall portion 141e in the X-axis direction. However, in the energy storage element 10g according to Modification 5, the structure consists of the two ends of the curved wall portion 141g in the X-axis direction, the two ends of the curved wall portion 151g in the X-axis direction, each terminal 300g, and each external pad 400g. In other words, one energy storage element 10g has four terminals 300.

[0163] (Other variations)

[0164] The above describes the energy storage element involved in the embodiments of the present invention (including its variations, as hereinafter the same), but the present invention is not limited to the above embodiments. The embodiments disclosed herein are illustrative in all respects, and all modifications in the sense and scope equivalent to those in the claims are included within the scope of the present invention.

[0165] Although not illustrated in the above embodiments, any structure in which the pressure from the curved surface of the retaining unit is transmitted to the curved wall of the container is acceptable. The invention also includes cases where the curved shape of the outer surface of the curved wall of the container is replaced with a generally circular polyhedral shape, and cases where the curved shape of the curved surface of the retaining unit is replaced with a polyhedral shape. Alternatively, at least one of the outer surface of the curved wall of the container and the curved surface of the retaining unit may have a curved shape with a curvature different from that of the inner surface of the curved wall, and / or one or more angles, and / or one or more planes. For example, at least one of the outer surface of the curved wall of the container and the curved surface of the retaining unit may be a polyhedron.

[0166] Although not illustrated in the above embodiments, the retaining unit may also be formed of foamed resin for portions other than the first retaining members 23 and 25. Furthermore, various methods for forming the retaining unit from foamed resin are conceivable. The retaining unit can be formed by filling foamed resin after placing the energy storage element within the energy storage device and then curing it, or by assembling pre-formed components constituting the retaining unit together with the energy storage element. The retaining unit may also be composed of a portion that is filled with foamed resin and cured within the energy storage device and a portion that is pre-formed before assembly of the energy storage device. In this case, the order of filling and curing a portion of the retaining unit with foamed resin within the energy storage device and assembling a pre-formed portion of the retaining unit within the energy storage device can be arbitrary and not particularly limited. For example, after positioning the energy storage element and the first retaining member (part of the retaining unit) opposite the curved wall portion of the energy storage element within the energy storage device, foamed resin may be filled to form a second retaining member (part of the retaining unit) opposite the flat wall portion of the energy storage element. In this example, a first retaining member (part of the retaining unit) pre-formed to a predetermined shape is disposed within the energy storage device along with the energy storage element. Furthermore, the material of the first retaining member (part of the retaining unit) pre-formed before assembly of the energy storage device can be foamed resin or a material different from foamed resin. Alternatively, the retaining unit can be formed by filling and curing the foamed resin once or multiple times after the energy storage element is positioned and configured. The constituent parts of the pre-formed retaining unit can also be assembled together with the energy storage element.

[0167] In the above embodiment, an energy storage device 1 in which multiple energy storage elements 10 are housed in a housing 2 is illustrated, but any energy storage device that houses one or more energy storage elements in a housing is acceptable.

[0168] In the above embodiment, the case where the external component is a box-shaped shell 2 is illustrated. The external component may also be formed from an aluminum die-casting. Furthermore, the external component may also be a component constituting the moving body itself, such as an automobile. Examples of the moving body itself include the frame structure of the moving body, a trolley, a chassis, etc.

[0169] In the above embodiments, an example is shown of a package-type energy storage device 1 in which the energy storage element 10 and the holding unit 20 are housed in the housing 2, but it may also be a modular energy storage device.

[0170] The invention also includes any combination of the constituent elements included in the above embodiments and their variations.

[0171] Industrial availability

[0172] This invention can be applied to energy storage components such as lithium-ion secondary batteries and energy storage devices incorporating such energy storage components.

[0173] -Explanation of Figure Markers-

[0174] 1. Energy storage device

[0175] 2. Shell (external components)

[0176] 10, 10c, 10d, 10e, 10f, 10g energy storage components

[0177] 20, 20A, 20B Holding Units

[0178] 21 Retaining components

[0179] 22 Refrigerant Road

[0180] 23, 25 First retaining member

[0181] 24, 26 Second retaining members

[0182] 30. Main body of the shell

[0183] 31 Opening

[0184] 32 bottom wall

[0185] 33 Sidewall

[0186] 37 Exhaust port

[0187] 40 Shell cover

[0188] 50 Exhaust components

[0189] 51 First Board Section

[0190] 52 Second Board Section

[0191] 53 Vent holes

[0192] 100, 100e container

[0193] 101 First recess (notch)

[0194] 102, 102c, 102f Second concave part (notch)

[0195] 110 First side profile

[0196] 112a Through hole

[0197] 120 Second side profile

[0198] 122a Through Hole

[0199] 130 Long Side

[0200] 131 Flat wall portion

[0201] 140 Top surface

[0202] 141, 141e, 151, 151g Curved wall portion

[0203] 150 Bottom

[0204] 160 Container Body

[0205] 170 Cap

[0206] 210 Intermediate spacer (retaining member)

[0207] 211, 221, 241, 261 Flat surfaces

[0208] 212, 213, 222, 223, 231, 251 Curved surfaces

[0209] 220 End spacer (retaining member)

[0210] 300, 300e terminal

[0211] 400 External Pad

[0212] 700 Electrode Body

[0213] 710 Main Body

[0214] 711 Bending section

[0215] 712 Flat section

[0216] 720 Electrode

[0217] 721 Positive electrode ear part

[0218] 722 Negative electrode ear part

[0219] 740 Positive Plate

[0220] 741 Positive current collector foil

[0221] 742 Positive Electrode Active Material Layer

[0222] 743, 753 protruding tablets

[0223] 750 negative electrode plate

[0224] 751 Negative electrode current collector foil

[0225] 752 Negative Electrode Active Material Layer

[0226] 761, 762 separators

[0227] 800, 800c, 800d, 800e Gas Discharge Valves

[0228] L winding shaft

[0229] L1 serves as the reference range for the shape of container 100 (shown by a double-dotted line).

[0230] S1 and S2 spaces.

Claims

1. An energy storage device, characterized in that, have: Energy storage components; and A retaining unit is disposed further outward than the energy storage element and retains the energy storage element. The energy storage element includes: Electrode body, with electrode plates wound around it; and Container, which houses the electrode body The electrode body is a flat shape having a pair of opposing flat portions and a pair of opposing curved portions. The container has: A flat wall portion, opposite to the flat portion of the electrode body; and The curved wall portion is opposite to the curved portion of the electrode body. The inner surface of the flat wall portion has a flat shape along the flat portion. The inner surface of the curved wall portion follows the curved shape of the curved portion. The inner surface of the retaining unit has: A flat surface is a flat shape along the outer surface of the flat wall portion of the container; as well as A curved surface is a curved shape along the outer surface of the curved wall portion of the container. The inner surface of the flat wall portion of the container presses against the flat portion of the electrode body. The inner surface of the curved wall portion of the container presses against the curved portion of the electrode body. The flat surface of the retaining unit presses against the outer surface of the flat wall portion of the container. The curved surface of the retaining unit presses against the outer surface of the curved wall portion of the container.

2. The energy storage device according to claim 1, wherein, The energy storage device includes: an external component or housing disposed further outward than the holding unit. The external component or the housing secures or accommodates the retaining unit. The outer surface of the retaining unit is pressed by the external member or the housing, resulting in a state where the curved surface of the retaining unit presses against the outer surface of the curved wall of the container of the energy storage element, and the flat surface of the retaining unit presses against the outer surface of the flat wall of the container of the energy storage element.

3. The energy storage device according to claim 2, wherein, The holding unit includes a plurality of holding members arranged in a direction opposite to the flat portion of the electrode body and the flat wall portion of the container. The inner surface of the retaining member has: The flat surface presses against the outer surface of the flat wall portion of the container; and The curved surface presses against the outer surface of the curved wall portion of the container.

4. The energy storage device according to claim 2, wherein, The holding unit includes: A pair of first retaining members clamp the energy storage element in a direction opposite to the curved portion of the electrode body and the curved wall portion of the container; and A pair of second retaining members clamp the energy storage element in a direction opposite to the flat portion and the flat wall portion. The pair of first retaining members are separate from the pair of second retaining members. The inner surface of the first retaining member has a curved surface that presses against the curved wall portion of the container. The inner surface of the second retaining member has a flat surface that presses against the flat wall portion of the container.

5. The energy storage device according to claim 4, wherein, The energy storage device includes multiple energy storage elements. The plurality of energy storage elements include a first energy storage element and a second energy storage element. The first energy storage element includes: The first electrode body has the same structure as the electrode body; and The first container has the same structure as the container mentioned above. The first electrode body has a flat shape having a first flat portion having the same structure as the flat portion and a first curved portion having the same structure as the curved portion. The first container has: The first flat wall portion has the same structure as the flat wall portion; and The first curved wall portion has the same structure as the curved wall portion. The second energy storage element includes: The second electrode body has the same structure as the electrode body; and The second container has the same structure as the first container. The second electrode body is a flat shape having a second flat portion having the same structure as the flat portion and a second curved portion having the same structure as the curved portion. The second container has: The second flat wall portion has the same structure as the said flat wall portion; and The second curved wall portion has the same structure as the aforementioned curved wall portion. The surface of the first flat wall portion of the first container of the first energy storage element and the surface of the second flat wall portion of the second container of the second energy storage element face each other. The inner surface of the first retaining member has a plurality of the curved surfaces integrally integrated. The plurality of curved surfaces have: The first curved surface is opposite to the first curved wall portion; as well as The second curved surface is opposite to the second curved wall portion. The first curved portion of the first electrode body is compressed because its outer surface is pressed by the first curved surface of the first retaining member. The second curved portion of the second electrode body is compressed because the outer surface of the second curved wall in the second container is pressed by the second curved surface of the first retaining member.

6. The energy storage device according to any one of claims 1 to 5, wherein, The retaining unit is formed of foamed resin.

7. The energy storage device according to any one of claims 1 to 5, wherein, The holding unit includes: a refrigerant path for refrigerant flow.

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