Electric power storage device

Abstract

To provide an electric power storage device which is appropriate for performing reuse to an electric power source for a mobile object or an electric power source for a fixed object by using an electric power storage element having short height.SOLUTION: An electric power storage device comprises a plurality of electric power storage elements each including a container which is based on a rectangular parallelepiped. In the electric power storage device, a length (L) in a length direction of the rectangular parallelepiped, a length (H) in a height direction and a length (T) in a width direction are in a relation of L>H>T. Both ends of the container in the length direction include four terminals of two positive electrode terminals and two negative electrode terminals. In one end in the length direction, two one-end terminals which are two terminals of four terminals are disposed and in the other end in the length direction, two other-end terminals which are the other two terminals of four terminals are disposed. An electric power storage element group is formed by disposing the plurality of electric power storage elements in parallel in the height direction. Regarding two electric power storage elements which are adjacent to each other in the height direction in the plurality of electric power storage elements, individual one-end terminals are electrically connected with each other, individual other-end terminals are electrically connected with each other, and a plurality of electric power storage element groups is laminated in the width direction and electrically connected.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device. [Background technology]

[0002] Conventionally, a battery pack configured by stacking multiple low-profile, rectangular prismatic cells has been known as an energy storage device for passenger-car-sized electric vehicles (see, for example, Patent Document 1). In this energy storage device, excess space within the battery pack is minimized to accommodate the batteries, thereby improving energy density. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7197689 Summary of the Invention [Problem to be solved by the invention]

[0004] Due to the structure of the body of electric vehicles, it is common for the battery pack to be housed under the floor, and it is necessary to make the battery pack low-profile (for example, 15 cm or less) especially in low-profile passenger car-sized electric vehicles. In order to make the battery pack low-profile, it is necessary to reduce the height of the batteries inside the battery pack, which means that the height of the individual cells needs to be low (for example, 10 cm or less).

[0005] On the other hand, there is a strong demand for electric vehicle batteries to be reused and recycled after use in electric vehicles from the perspectives of resource conservation, reducing carbon dioxide emissions, and reducing battery prices. Looking at the overall market for large lithium-ion batteries, the number of lithium-ion batteries used in passenger car-sized electric vehicles is overwhelmingly large. In other words, it is extremely important whether lithium-ion batteries used in passenger car-sized electric vehicles can be reused for other purposes.

[0006] Specifically, there is a demand for secondary uses of passenger car-sized electric vehicle batteries, after they have been used in electric vehicles, such as as power sources for bus- and truck-sized electric vehicles, as power sources for mobile objects including industrial vehicles such as forklifts and construction equipment, and as stationary power sources for power storage, load adjustment, and the like.

[0007] However, low-profile electric vehicle batteries have dimensional issues when it comes to secondary use in other applications. Specifically, when used as a power source for bus- or truck-sized electric vehicles, or for mobile vehicles such as forklifts and construction equipment, the body size of these vehicles is larger than that of passenger cars, so larger batteries are preferred. Furthermore, the required battery capacity for these applications is large, so the power supply system must use multiple low-profile battery packs, which reduces the energy density of the power supply system and increases costs.

[0008] Furthermore, when reusing batteries for stationary power sources such as power storage, if low-profile battery packs are used in large-scale power storage systems, it is necessary to control the temperature of each battery pack, making the system complicated.Furthermore, with low-profile battery packs, the number of packs required for the power storage system increases, reducing the energy density of the system and increasing costs.

[0009] An object of the present disclosure is to provide an energy storage device that is suitable for reusing low-profile lithium-ion batteries produced as power sources for passenger car-sized electric vehicles for other uses, such as power sources for mobile bodies or stationary power sources. [Means for solving the problem]

[0010] According to one aspect of the present invention, there is provided an energy storage device comprising a plurality of energy storage elements each having a container based on a rectangular parallelepiped, wherein the longitudinal length (L), height (H), and width (T) of the rectangular parallelepiped satisfy the relationship L>H>T, and both longitudinal end portions of the container are provided with four terminals, namely, two positive electrode terminals and two negative electrode terminals, and two one-end terminals, which are two of the four terminals, are arranged at one longitudinal end portion, and two other-end terminals, which are the other two of the four terminals, are arranged at the other longitudinal end portion, and the plurality of energy storage elements are arranged in the height direction to form an energy storage element group, and two adjacent energy storage elements among the plurality of energy storage elements in the height direction are electrically connected at one of the one-end terminals and at one of the other-end terminals, and the plurality of energy storage element groups are stacked in the width direction and electrically connected. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an electricity storage device that uses low-profile electricity storage elements and is suitable for reuse as a power source for a mobile body or a stationary power source. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is an exploded perspective view showing each component of an electricity storage device according to an embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the electricity storage unit according to the embodiment. [Figure 3] FIG. 3 is a perspective view showing the appearance of the energy storage device according to the embodiment. [Figure 4] FIG. 4 is an exploded perspective view showing the components of the energy storage device according to the embodiment. [Figure 5] FIG. 5 is a perspective view showing the configuration of an electrode body according to the embodiment. [Figure 6] FIG. 6 is a plan view showing an energy storage element group according to the embodiment. [Figure 7] FIG. 7 is a perspective view showing a part of a plurality of power storage units according to the embodiment in an expanded state. [Figure 8] FIG. 8 is a plan view showing an energy storage element group according to the first modification. [Figure 9] FIG. 9 is an exploded perspective view showing the components of the energy storage device according to the second modification. [Figure 10] FIG. 10 is an explanatory diagram showing a spacer provided in an energy storage element group according to the second modification. DETAILED DESCRIPTION OF THE INVENTION

[0013] (1) According to one aspect of the present invention, there is provided a power storage device comprising a plurality of power storage elements each having a container based on a rectangular parallelepiped, wherein the longitudinal length (L), height (H), and width (T) of the rectangular parallelepiped satisfy the relationship L>H>T, and both longitudinal end portions of the container are provided with four terminals, i.e., two positive electrode terminals and two negative electrode terminals, and two of the four terminals, i.e., two one-end terminals, are arranged at one longitudinal end portion, and two other-end terminals, i.e., the other two of the four terminals, are arranged at the other longitudinal end portion, and the plurality of power storage elements are arranged in the height direction to form a power storage element group, and two adjacent power storage elements among the plurality of power storage elements in the height direction are electrically connected at one of the one-end terminals and at one of the other-end terminals, and the plurality of power storage element groups are stacked in the width direction and electrically connected.

[0014] According to the energy storage device described in (1) above, it is possible to provide an energy storage device that is suitable for reusing low-profile, rectangular energy storage elements that have conventionally been used in energy storage devices for passenger car-sized electric vehicles for other applications such as mobile power sources or stationary power sources.

[0015] (2) In the energy storage device described in (1) above, the one end terminal on one side in the height direction among the two one end terminals and the other end terminal on the one side in the height direction among the two other end terminals may have different polarities, and the one end terminal on the other side in the height direction among the two one end terminals and the other end terminal on the other side in the height direction among the two other end terminals may have different polarities.

[0016] According to the energy storage device described in (2) above, in each energy storage element, the one end terminal on one side in the height direction and the other end terminal on one side in the height direction have different polarities, and the one end terminal on the other side in the height direction and the other end terminal on the other side in the height direction have different polarities, so that multiple energy storage elements lined up in the height direction can be easily connected in parallel.

[0017] (3) In the energy storage device described in (1) or (2) above, the two one-end terminals may be one of the two positive electrode terminals and one of the two negative electrode terminals, and the two other-end terminals may be the other of the two positive electrode terminals and the other of the two negative electrode terminals.

[0018] According to the energy storage device described in (3) above, when connecting the first end terminals of two energy storage elements, various connections are possible, such as connecting the positive terminals together or the negative terminals together (parallel connection), or connecting the positive terminals and the negative terminals together (series connection).

[0019] (4) In the energy storage device described in any one of (1) to (3) above, the two one-end terminals may be arranged on both surfaces of the one end in the height direction, and the two other-end terminals may be arranged on both surfaces of the other end in the height direction.

[0020] According to the energy storage device described in (4) above, by arranging the one-end terminals on both surfaces of one end of the energy storage elements in the arrangement direction, the length of the bus bar electrically connecting the one-end terminals of the two energy storage elements can be made shorter.

[0021] (5) In the energy storage device described in any one of (1) to (4) above, two of the plurality of energy storage element groups that are adjacent in the width direction may have energy storage elements at ends in the height direction electrically connected in series.

[0022] According to the energy storage device described in (5) above, among the multiple energy storage element groups stacked in the width direction, in two adjacent energy storage element groups, the energy storage elements at the ends in the height direction are electrically connected in series, so that the length of the bus bar connecting the adjacent energy storage element groups can be shortened.

[0023] (6) In the energy storage device described in any one of (1) to (5) above, each of the plurality of energy storage elements may have a notch on both sides of the height direction at the one end, in which the two one end terminals are arranged, and a notch on both sides of the height direction at the other end, in which the two other end terminals are arranged.

[0024] According to the electricity storage device described above in (6), conductive members such as bus bars connected to the terminals can be disposed within the cutouts, thereby saving space.

[0025] (Embodiment) Hereinafter, with reference to the drawings, a description will be given of an energy storage device according to an embodiment of the present invention (including modifications thereof). Note that the embodiments described below all show comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples and are not intended to limit the present invention. In each drawing, dimensions and the like are not strictly illustrated. In each drawing, the same reference numerals are used for identical or similar components. The names of the components (each component) in this embodiment are those used in this embodiment and may differ from the names of the components (each component) in the background art.

[0026] In the following description and drawings, the arrangement direction, height direction, and up-down direction of multiple storage elements included in one storage element group are defined as the Z-axis direction. The longitudinal direction of each storage element is defined as the X-axis direction. The width direction of each storage element is defined as the Y-axis direction. These X-axis, Y-axis, and Z-axis directions intersect with each other (orthogonal in this embodiment). Depending on the usage mode, the Z-axis direction may not be the up-down direction, but for convenience of explanation, the following description will be made assuming that the Z-axis direction is the up-down direction.

[0027] In the following explanation, for example, the positive X-axis direction indicates the direction of the arrow on the X-axis, and the negative X-axis direction indicates the opposite direction to the positive X-axis direction. The same applies to the Y-axis direction and the Z-axis direction. Furthermore, expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the direction or attitude is not strictly that. For example, "two directions are perpendicular" does not only mean that the two directions are completely perpendicular, but also means that the two directions are substantially perpendicular, that is, there is a difference of, for example, a few percent. In the following explanation, when the term "insulation" is used, it means "electrical insulation." An insulating material has a volume resistivity of 1×10 6 Ωm or more is preferable, and 1×10 7 Ωm or more is preferable, and 1×10 10 More preferably, it is Ωm or more.

[0028] [Electricity storage device] First, a schematic configuration of a power storage device 1 according to the present embodiment will be described. FIG. 1 is an exploded perspective view showing each component of the power storage device 1 according to the embodiment. The power storage device 1 is a device that can be charged with electricity from an external source or discharged to an external source, and in this embodiment, has a substantially rectangular parallelepiped shape. The rectangular parallelepiped here refers to a hexahedron with all faces formed of rectangles or squares. The power storage device 1 is a battery module (battery assembly) used for power storage purposes, load adjustment, and other power source purposes. Specifically, the power storage device 1 is used as a battery for driving or starting the engine of a moving object such as a passenger car, motorcycle, bus, truck, personal watercraft, ship, snowmobile, agricultural machinery, construction machinery, automatic guided vehicle (AGV), or electric railway vehicle. Examples of such vehicles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicles. Examples of the electric railway vehicle include electric trains, monorails, linear motor cars, and hybrid trains equipped with both a diesel engine and an electric motor. In addition to these, the power storage device 1 can also be used as a stationary battery for home or business use.

[0029] As shown in FIG. 1, the energy storage device 1 includes a case 2. Inside the case 2, a plurality of energy storage units 4 are housed and arranged in a matrix when viewed from the Z-axis direction. Specifically, 33 energy storage units 4 are arranged in three columns in the Y-axis direction and in the X-axis direction. That is, the plurality of energy storage units 4 are arranged in a matrix of 3 columns and 33 rows. Each of the plurality of energy storage units 4 includes a plurality of energy storage elements 10 (see FIG. 2). Inside the case 2, a bus bar 29 (see FIG. 7) for electrically connecting the energy storage units 4 is also housed. The energy storage device 1 also includes external terminals (positive electrode external terminal and negative electrode external terminal: not shown) for electrically connecting to an external device. Each external terminal may be installed on the outer surface of the case 2, and the installation location may be arbitrary. One positive electrode external terminal and one negative electrode external terminal may be installed on the case 2, or multiple positive electrode external terminals and multiple negative electrode external terminals may be installed on the case 2.

[0030] In addition to the above components, the energy storage device 1 may also include restraining members (end plates, side plates, etc.) that restrain the multiple energy storage units 4, a bus bar holder that holds the bus bar 29, a bus bar cover, a circuit board that monitors or controls the charge state and discharge state of the energy storage elements 10, electrical components such as relays, fuses, shunt resistors and connectors, exhaust members that form an exhaust path for gases discharged from each energy storage element 10, exhaust ports, etc.

[0031] The case 2 is a substantially rectangular parallelepiped (box-shaped) container (module case) that constitutes the exterior body (housing, outer shell) of the energy storage device 1. The case 2 is disposed outside the plurality of energy storage units 4, etc., and secures the plurality of energy storage units 4, etc. in predetermined positions to protect them from impacts and the like. The case 2 is a metal case made of a metal member such as aluminum, aluminum alloy, stainless steel, iron, or plated steel sheet. The case 2 may be made of an insulating material such as any resin material that can be used for the holder 44 described below. When the case 2 is made of a conductive material, the inner surface of the case 2 may be coated with an insulating material to ensure insulation from the energy storage elements.

[0032] The case 2 has a case main body 20 that constitutes the main body of the case 2, and a first cover body 21 and a second cover body 22 that constitute covers of the case 2. The case main body 20 is a housing (casing) in which an opening 23 that is continuous in the positive Z-axis direction and the negative Y-axis direction is formed, and houses a plurality of power storage units 4.

[0033] Specifically, the case body 20 has a bottom wall 24 and side walls 25. The bottom wall 24 is a flat, rectangular portion located at the end of the case body 20 in the negative Z-axis direction. The side walls 25 are walls extending in the positive Z-axis direction from three sides of the bottom wall 24 other than the side in the negative Y-axis direction. The case body 20 may be provided with an exhaust port (not shown) that exhausts gas discharged from each energy storage element 10 to the outside of the case 2.

[0034] The first lid 21 is a rectangular plate-shaped member that closes the area in the negative Y-axis direction of the opening 23 of the case body 20. The first lid 21 is joined to the edges of the bottom wall 24 and the side wall 25 of the case body 20 in the negative Y-axis direction by welding, melting, screwing, or the like.

[0035] The second cover 22 is a rectangular plate-shaped member that closes the area in the positive direction of the Z axis of the opening 23 of the case body 20. The second cover 22 is joined to the side wall 25 of the case body 20 and the edge of the first cover 21 in the positive direction of the Z axis by welding, fusion, screwing, or the like.

[0036] The first cover 21 and the second cover 22 may be made of the same material as the case body 20, or may be made of a different material.

[0037] [Energy storage unit] 2 is an exploded perspective view of the energy storage unit 4 according to the embodiment. As shown in FIG. 2, the energy storage unit 4 includes an energy storage element group 41, a plurality of bus bars 42, a plurality of protective covers 43, and a holder 44.

[0038] The energy storage element group 41 includes a plurality of energy storage elements 10 arranged in the Z-axis direction (height direction). In the present embodiment, an example is shown in which the energy storage element group 41 includes three energy storage elements 10, but one energy storage element group 41 may include any number of energy storage elements 10 as long as it includes two or more energy storage elements 10. Details of the energy storage elements 10 will be described later.

[0039] The multiple bus bars 42 are conductive members that electrically connect two energy storage elements 10 adjacent to each other in the Z-axis direction. Each bus bar 42 is formed in a U-shape and is connected (joined) to a terminal 300 provided on the energy storage element 10. Of the multiple bus bars 42, each bus bar 42 arranged in the positive direction of the X-axis is arranged with the bottom of its U-shape facing the positive direction of the X-axis, and each bus bar 42 arranged in the negative direction of the X-axis is arranged with the bottom of its U-shape facing the negative direction of the X-axis. The bus bars 42 and the terminals 300 are connected (joined) by welding or the like, but the connection form is not particularly limited. The bus bars 42 are formed from a conductive member made of a metal such as aluminum, an aluminum alloy, copper, a copper alloy, or nickel, or a combination thereof, or a conductive member other than a metal.

[0040] The multiple protective covers 43 are members that cover and protect each bus bar 42. The protective covers 43 are plate-shaped insulating members that are U-shaped when viewed from the positive direction of the Z axis. Of the multiple protective covers 43, each protective cover 43 arranged in the positive direction of the X axis is arranged with the bottom of its U-shape facing the positive direction of the X axis, and each protective cover 43 arranged in the negative direction of the X axis is arranged with the bottom of its U-shape facing the negative direction of the X axis. Each protective cover 43 is assembled to two energy storage elements 10 adjacent to each other in the Z axis direction by fitting or bonding. After assembly, each protective cover 43 entirely covers and protects each bus bar 42. The protective covers 43 are formed from an insulating material such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), ABS resin, or a composite material thereof, or a heat-insulating material such as mica.

[0041] The holder 44 is a cylindrical insulating member that houses and covers the energy storage element group 41, the multiple bus bars 42, and the multiple protective covers 43. The holder 44 is a rectangular tube that penetrates in the Z-axis direction. Specifically, the holder 44 has a shape based on a rectangular parallelepiped, and four corners are cut out in a rectangular shape when viewed in the Y-axis direction. The holder 44 protects and limits misalignment of the energy storage element group 41, the multiple bus bars 42, and the multiple protective covers 43 inside. The holder 44 may be integrated with the energy storage element group 41, the multiple bus bars 42, and the multiple protective covers 43 by fitting or adhering them to the holder 44. The energy storage element group 41, the multiple bus bars 42, and the multiple protective covers 43 may be integrated with the holder 44 by providing cover plates (not shown) at both ends of the holder 44 in the Z-axis direction. The holder 44 is formed from an insulating material such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), ABS resin, or a composite material thereof, or a heat-insulating material such as mica.

[0042] [Energy storage element] An overall description of the energy storage device 10 according to the embodiment will be given with reference to Figures 3 and 4. Figure 3 is a perspective view showing the appearance of the energy storage device 10 according to the embodiment. Figure 4 is an exploded perspective view showing the components of the energy storage device 10 according to the embodiment.

[0043] The energy storage element 10 is an energy storage element that can be charged with electricity from an external source or can discharge electricity to an external source, and in this embodiment, has a substantially rectangular parallelepiped shape. The energy storage element 10 is not limited to a nonaqueous electrolyte secondary battery, and may be a secondary battery other than a nonaqueous electrolyte secondary battery, or a capacitor. The energy storage element 10 may be a primary battery instead of a secondary battery. Furthermore, the energy storage element 10 may be, for example, an all-solid-state lithium battery using a solid electrolyte, or a polymer lithium battery. The energy storage element 10 may also be a pouch-type energy storage element. In this embodiment, the energy storage element 10 is illustrated based on a flat rectangular parallelepiped shape (a substantially rectangular parallelepiped shape). However, the shape of the energy storage element 10, i.e., the shape of the container 100, is not limited to a shape based on a rectangular parallelepiped shape, and may be a shape based on a polygonal prism shape other than a rectangular parallelepiped, an elongated cylinder shape, an elliptical cylinder shape, a cylindrical shape, or the like.

[0044] As shown in FIGS. 3 and 4, the energy storage element 10 includes a container 100, four terminals 300, and four external gaskets 400. The container 100 contains four internal gaskets 500, four current collectors 600, and an electrode assembly 700. An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but is not shown. The type of electrolyte is not particularly limited as long as it does not impair the performance of the energy storage element 10, and various types can be selected. In addition to the above components, spacers arranged on the sides, above, or below the electrode assembly 700, an insulating film that wraps around the electrode assembly 700, etc. may also be arranged.

[0045] The container 100 is a case having an external shape (approximately rectangular parallelepiped shape) based on a rectangular parallelepiped shape that is long and flat in the X-axis direction. The rectangular parallelepiped shape that serves as the base of the container 100 has a longitudinal length (L: length in the X-axis direction), a height length (H: length in the Z-axis direction), and a width length (T: length in the Y-axis direction) such that L>H>T. The lengths of the container 100 in the X-axis direction and the Y-axis direction may be equal, or the length in the Y-axis direction may be longer than the length in the X-axis direction. In FIG. 3 , the base rectangular parallelepiped shape is illustrated by a two-dot chain line L1. Specifically, the container 100 has an external shape that is long in the X-axis direction and flat in the Y-axis direction, with four rectangular cutouts formed at the top and bottom of both ends in the X-axis direction. Each cutout can be considered to form a recess when viewed from the base rectangular parallelepiped shape. Of the multiple cutouts, a pair of cutouts located in the upper part of the container 100 each form a first recess 101, and a pair of cutouts located in the lower part of the container 100 each form a second recess 102. In other words, at both ends of the container 100 in the X-axis direction, the first recess 101 and the second recess 102 are formed at different positions in the Z-axis direction so as to face each other in the Z-axis direction.

[0046] Here, the X-axis direction is the longitudinal direction of the energy storage device 10, one end of the container 100 in the positive X-axis direction is the first side surface portion 110, and the other end in the negative X-axis direction is the second side surface portion 120.

[0047] Specifically, the first side surface portion 110 has a first upper side surface 111, a first top surface 112, a first middle side surface 113, a first bottom surface 114, and a first lower side surface 115, and is elongated in the Z-axis direction when viewed in the X-axis direction. The first upper side surface 111 is disposed at the top of the first side surface portion 110 and is a rectangular plane parallel to the YZ plane and elongated in the Z-axis direction. The first top surface 112 is a plane extending from the lower end of the first upper side surface 111 in the positive X-axis direction and is a rectangular plane parallel to the XY plane and elongated in the X-axis direction. The first middle side surface 113 is a plane extending downward from the end of the first upper surface 112 in the positive X-axis direction and is a rectangular plane parallel to the YZ plane and elongated in the Z-axis direction. The first lower surface 114 is a plane extending from the lower end of the first middle side surface 113 in the negative X-axis direction and is a rectangular plane parallel to the XY plane and elongated in the X-axis direction. The first lower side surface 115 is a plane that extends downward from the end of the first lower surface 114 in the negative X-axis direction, and is a rectangular plane that is parallel to the YZ plane and elongated in the Z-axis direction.

[0048] The first recess 101 of the first side surface portion 110 is formed by a first upper side surface 111 and a first upper surface 112, and is open at its end in the positive Z-axis direction and its end in the positive X-axis direction. The second recess 102 of the first side surface portion 110 is formed by a first lower surface 114 and a first lower side surface 115, and is open at its end in the negative Z-axis direction and its end in the positive X-axis direction. Therefore, at the end of the first side surface portion 110 in the positive Z-axis direction (a corner of the container 100 in the positive X-axis and positive Z-axis directions), the wall surfaces in the X-axis and Z-axis directions are recessed and the wall surfaces are penetrated in the Y-axis direction. On the other hand, at the end of the first side surface portion 110 in the negative Z-axis direction (a corner of the container 100 in the positive X-axis and negative Z-axis directions), the wall surfaces in the X-axis and Z-axis directions are recessed and the wall surfaces are penetrated in the Y-axis direction.

[0049] The second side surface portion 120 has a second upper side surface 121, a second top surface 122, a second middle side surface 123, a second bottom surface 124, and a second lower side surface 125, and is elongated in the Z-axis direction when viewed in the X-axis direction. The second upper side surface 121 is disposed at the top of the second side surface portion 120 and is a rectangular plane parallel to the YZ plane and elongated in the Z-axis direction. The second top surface 122 is a plane extending from the lower end of the second upper side surface 121 in the negative X-axis direction and is a rectangular plane parallel to the XY plane and elongated in the X-axis direction. The second middle side surface 123 is a plane extending downward from the end of the second upper surface 122 in the negative X-axis direction and is a rectangular plane parallel to the YZ plane and elongated in the Z-axis direction. The second lower surface 124 is a plane extending from the lower end of the second middle side surface 123 in the positive X-axis direction and is a rectangular plane parallel to the XY plane and elongated in the X-axis direction. The second lower side surface 125 is a plane that extends downward from the end of the second lower surface 124 in the positive X-axis direction, and is a rectangular plane that is parallel to the YZ plane and elongated in the Z-axis direction.

[0050] The first recess 101 of the second side surface portion 120 is formed by a second upper side surface 121 and a second upper surface 122, and is open at its end in the positive Z-axis direction and its end in the negative X-axis direction. The second recess 102 of the second side surface portion 120 is formed by a second lower surface 124 and a second lower side surface 125, and is open at its end in the negative Z-axis direction and its end in the negative X-axis direction. Therefore, at the end of the second side surface portion 120 in the positive Z-axis direction (a corner portion of the container 100 in the negative X-axis direction and the positive Z-axis direction), the wall surfaces in the X-axis and Z-axis directions are recessed and the wall surfaces are penetrated in the Y-axis direction. On the other hand, at the end of the second side surface portion 120 in the negative Z-axis direction (a corner portion of the container 100 in the negative X-axis and the negative Z-axis direction), the wall surfaces in the X-axis and Z-axis directions are recessed and the wall surfaces are penetrated in the Y-axis direction.

[0051] In this container 100, both end faces opposing each other in the Y-axis direction are long side faces 130. Each long side face 130 is a flat surface parallel to the XZ plane and elongated in the X-axis direction, and both end portions in the X-axis direction have shapes corresponding to the first side face portion 110 and the second side face portion 120.

[0052] Of the two end faces of the container 100 that face each other in the Z-axis direction, the end face in the positive Z-axis direction is the top face 140, and the end face in the negative Z-axis direction is the bottom face 150. The top face 140 is a rectangular flat surface that is parallel to the XY plane and elongated in the X-axis direction, connecting the upper end of the first upper side face 111 of the first side face portion 110 and the upper end of the second upper side face 121 of the second side face portion 120. The bottom face 150 is a rectangular flat surface that is parallel to the XY plane and elongated in the X-axis direction, connecting the lower end of the first lower side face 115 of the first side face portion 110 and the lower end of the second lower side face 125 of the second side face portion 120.

[0053] Container 100 has a container body 160 and a lid 170, and is formed into a substantially rectangular parallelepiped shape by assembling container body 160 and lid 170. Container body 160 has a pair of long sides 130 and a bottom surface 150. Lid 170 has a first upper side surface 111, a first top surface 112, a first middle side surface 113, a first bottom surface 114, a first lower side surface 115, a second upper side surface 121, a second top surface 122, a second middle side surface 123, a second bottom surface 124, a second lower side surface 125, and a top surface 140.

[0054] Specifically, the container body 160 is a metal plate that is generally U-shaped and open at the top when viewed in the X-axis direction. The container body 160 has flat long side wall portions that form a pair of long sides 130 at both ends in the Y-axis direction, and a flat, rectangular bottom wall portion that forms the bottom surface 150 at the end in the negative Z-axis direction.

[0055] The lid 170 has a shape that is open downward when viewed in the Y-axis direction. The lid 170 has a bent plate portion at its end in the positive direction of the X-axis, which has 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, and at its end in the negative direction of the X-axis, which has a bent plate portion at its end in the negative direction of the X-axis, which has a second upper side surface 121, a second upper surface 122, a second middle side surface 123, a second lower surface 124, and a second lower side surface 125. The lid 170 has a flat, rectangular top wall portion at its end in the positive direction of the Z-axis, which has a top surface 140.

[0056] With this configuration, the container 100 is structured so that after the electrode assembly 700 and the like are housed inside the container body 160, the container body 160 and the lid 170 are joined by welding or the like, thereby sealing the interior. The material of the container 100 (container body 160 and lid 170) is not particularly limited, but is preferably a weldable metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet.

[0057] Here, the lid 170 is formed with a liquid injection portion (not shown) and a gas release valve 800. The liquid injection portion is a portion for injecting an electrolyte into the container 100 when manufacturing the energy storage element 10. The gas release valve 800 is a safety valve that releases pressure when the pressure inside the container 100 rises excessively. In this embodiment, the gas release valve 800 is provided on the first lower side surface 115.

[0058] The terminals 300 are terminals (positive electrode terminal and negative electrode terminal) electrically connected to the electrode assembly 700 via the current collector 600. In other words, the terminals 300 are metal members that lead out electricity stored in the electrode assembly 700 to the external space of the energy storage element 10 and introduce electricity into the internal space of the energy storage element 10 in order to store electricity in the electrode assembly 700. The material of the terminals 300 is not particularly limited, but the terminals 300 are formed, for example, from a conductive material such as aluminum, an aluminum alloy, copper, or a copper alloy. The terminals 300 are attached to the lid 170 and connected (joined) to the current collector 600 by crimping, welding, or the like.

[0059] In this embodiment, the terminal 300 has a terminal body 330 and a shaft 340 protruding from the terminal body 330. The terminal body 330 is a portion protruding outward from the terminal installation surface of the container 100. Here, the terminal installation surfaces are the first upper surface 112, the first lower surface 114, the second upper surface 122, and the second lower surface 124. The terminal body 330 protrudes outward from any of the terminal installation surfaces of the container 100 along the Z-axis direction. Through holes 112a, 114a, 122a, and 124a through which the shaft 340 penetrates are formed in the lid 170 at locations corresponding to each terminal installation surface. The shaft 340 is connected (joined) to the current collector 600 by being crimped while penetrating the terminal installation surface of the lid 170, the external gasket 400, the internal gasket 500, and the current collector 600.

[0060] The current collectors 600 are arranged two at each end of the electrode body 700 in the X-axis direction, and are connected (joined) to the electrode body 700 and the terminal 300. These current collectors are conductive current collecting members that electrically connect the electrode body 700 and the terminal 300. Specifically, the current collector 600 integrally includes a first joint portion 630 and a second joint portion 640. The first joint portion 630 is connected (joined) to a tab portion 720 of the electrode body 700 (described later) by welding, crimping, or the like. The second joint portion 640 is connected (joined) to the terminal 300 by crimping, welding, or the like. The first joint portion 630 and the second joint portion 640 are each a flat plate-like portion formed by bending a single metal plate. The material of the current collector 600 is not particularly limited, but is preferably formed from a conductive material such as aluminum, an aluminum alloy, copper, or a copper alloy.

[0061] The external gasket 400 is a plate-shaped insulating sealing member that is disposed between the lid 170 of the container 100 and the terminal 300, and provides insulation and sealing between the lid 170 and the terminal 300. The internal gasket 500 is a plate-shaped insulating sealing member that is disposed between the lid 170 and the current collector 600, and provides insulation and sealing between the lid 170 and the current collector 600. In this embodiment, the external gasket 400 and the internal gasket 500 are rectangular. The external gasket 400 and the internal gasket 500 are formed from an electrically insulating resin, such as polypropylene (PP), polyethylene (PE), polystyrene (PS), ABS resin, or a composite material thereof.

[0062] The electrode body 700 is an electricity storage element (power generating element) formed by winding electrode plates and capable of storing electricity. The electrode body 700 has an elongated shape extending in the X-axis direction, and has an oval shape when viewed from the X-axis direction. The electrode body 700 may be longer in the X-axis direction than in the Z-axis direction. The electrode body 700 has a main body portion 710 and a plurality of tab portions 720 protruding from the main body portion 710, and as described above, the tab portions 720 are connected (joined) to the current collector 600.

[0063] Specifically, the multiple tab portions 720 protrude two by two from each of both end faces in the X-axis direction of the main body portion 710. A positive electrode tab portion 721 and a negative electrode tab portion 722 are provided on one end face of the main body portion 710 in the positive X-axis direction, and a positive electrode tab portion 721 and a negative electrode tab portion 722 are provided on the other end face of the main body portion 710 in the negative X-axis direction.

[0064] [Electrode body] Fig. 5 is a perspective view showing the configuration of an electrode assembly 700 according to an embodiment. Specifically, Fig. 5 shows the configuration in a partially developed state in which the wound state of the electrode plates in the electrode assembly 700 is shown. As shown in Fig. 5, the electrode assembly 700 has a positive electrode plate 740, a negative electrode plate 750, and separators 761 and 762.

[0065] The positive electrode plate 740 is an electrode plate in which a positive electrode active material layer 742 is formed on the surface of a positive electrode current collector foil 741, which is a long strip of metal foil. Aluminum, an aluminum alloy, or the like is used for the positive electrode current collector foil 741. The negative electrode plate 750 is an electrode plate in which a negative electrode active material layer 752 is formed on the surface of a negative electrode current collector foil 751, which is a long strip of metal foil. Copper, a copper alloy, or the like is used for the negative electrode current collector foil 751. As the positive electrode active material used in the positive electrode active material layer 742 and the negative electrode active material used in the negative electrode active material layer 752, any known material can be used as long as they are capable of absorbing and releasing lithium ions.

[0066] For example, the positive electrode active material may be a polyanion compound such as LiMPO4, LiMSiO4, or LiMBO3 (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), lithium titanate, LiMn2O4, or LiMn 1.5 Ni 0.5 Examples of the negative electrode active material that can be used include spinel-type lithium manganese oxides such as O4, and lithium transition metal oxides such as LiMO2 (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.). Examples of the negative electrode active material include lithium metal, alloys capable of absorbing and desorbing lithium, carbon materials (e.g., graphite, non-graphitizable carbon, graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), and silicon oxides.

[0067] Separators 761, 762 are microporous sheets made of resin. Any known material can be used as the material for separators 761, 762 as long as it does not impair the performance of energy storage element 10. For example, separators 761, 762 can be made of woven fabric or nonwoven fabric that is insoluble in organic solvents, or a synthetic resin microporous film made of a polyolefin resin such as polyethylene.

[0068] The electrode assembly 700 is formed by winding a positive electrode plate 740, a negative electrode plate 750, and separators 761 and 762. Specifically, the electrode assembly 700 is formed by stacking the negative electrode plate 750, the separator 761, the positive electrode plate 740, and the separator 762 in this order and winding them. In this embodiment, the wound electrode assembly 700 is formed by winding the positive electrode plate 740, the negative electrode plate 750, etc. around a winding axis L extending in the X-axis direction. The winding axis L is an imaginary axis that serves as the central axis when winding the positive electrode plate 740, the negative electrode plate 750, etc. In this embodiment, the winding axis L is a straight line that passes through the center of the electrode assembly 700 and is parallel to the X-axis direction.

[0069] A plurality of protruding pieces 743 protruding outward are arranged at intervals on both end edges of the positive electrode plate 740 in the direction of the winding axis (X-axis). Similarly, a plurality of protruding pieces 753 protruding outward are arranged at intervals on both end edges of the negative electrode plate 750 in the direction of the winding axis. Each of the protruding pieces 743, 753 is a portion (active material layer non-formed portion) where an active material layer containing an active material is not formed and the metal foil (current collector foil) is exposed. The hatched areas in FIG. 5 correspond to the active material layer non-formed portions.

[0070] When the positive electrode plate 740, the negative electrode plate 750, and the separators 761, 762 are wound, the protruding pieces 743 of the positive electrode plate 740 overlap each other, and the protruding pieces 753 of the negative electrode plate 750 overlap each other at each end face (one end face and the other end face) of the main body portion 710. In this embodiment, each end face of the main body portion 710 is the surface of the electrode body 700 when viewed from the X-axis direction. The portion where the protruding pieces 743 of the positive electrode plate 740 overlap each other is the positive electrode tab portion 721. In other words, the positive electrode tab portion 721 is a portion formed by stacking multiple pieces (protruding pieces 743) of electrode plates (positive electrode plates 740) of the same polarity among the multiple electrode plates (positive electrode plates 740 and negative electrode plates 750).

[0071] Similarly, the portion where the protruding pieces 753 of the negative electrode plates 750 overlap each other is the negative electrode tab portion 722. In other words, the negative electrode tab portion 722 is a portion formed by stacking a plurality of pieces (protruding pieces 753) of electrode plates (negative electrode plates 750) of the same polarity among the plurality of electrode plates (positive electrode plates 740 and negative electrode plates 750).

[0072] As described above, the electrode assembly 700 has a main body portion 710 that constitutes the main body of the electrode assembly 700, and a plurality of tab portions 720 (positive electrode tab portion 721 and negative electrode tab portion 722) that protrude in pairs from each of both end faces in the X-axis direction of the main body portion 710. Specifically, on the end face of the main body portion 710 in the positive X-axis direction, the negative electrode tab portion 722 is arranged at the top (positive Z-axis direction), and the positive electrode tab portion 721 is arranged at the bottom (negative Z-axis direction). On the end face of the main body portion 710 in the negative X-axis direction, the positive electrode tab portion 721 is arranged at the top, and the negative electrode tab portion 722 is arranged at the bottom.

[0073] The main body portion 710 is an elongated cylindrical portion (active material layer forming portion) formed by winding together a portion of the positive electrode plate 740 on which the positive electrode active material layer 742 is formed (coated), a portion of the negative electrode plate 750 on which the negative electrode active material layer 752 is formed (coated), and separators 761, 762. The main body portion 710 has a pair of curved portions 711 at each end in the Z-axis direction, and a flat portion 712 that is flat overall between the pair of curved portions 711. It can also be said that the pair of curved portions 711 are arranged at positions sandwiching the flat portion 712 in the Z-axis direction.

[0074] [Energy storage element group] Next, the energy storage element group 41 provided in one energy storage unit 4 will be described. FIG. 6 is a plan view showing the energy storage element group 41 according to the embodiment. In FIG. 6, for ease of explanation, the polarity of each terminal 300 is illustrated by a mark ("+" for positive pole, "-" for negative pole). Such a mark may or may not be provided on the actual energy storage element 10. The polarity of each terminal 300 on the actual energy storage element 10 may be identified by a color.

[0075] As shown in FIG. 6 , the three energy storage elements 10 constituting the energy storage element group 41 are arranged side by side in the Z-axis direction. Here, the energy storage element 10 in the positive direction of the Z-axis is referred to as the first energy storage element 11, the energy storage element 10 in the negative direction of the Z-axis is referred to as the third energy storage element 13, and the energy storage element 10 between them is referred to as the second energy storage element 12. The first energy storage element 11, the second energy storage element 12, and the third energy storage element 13 are all of the same type, but the first energy storage element 11 and the third energy storage element 13 are arranged in the same orientation, and the second energy storage element 12 is arranged inverted in the Z-axis direction. In this embodiment, a case is illustrated in which the bottom surface 150 of the first energy storage element 11 and the bottom surface 150 of the second energy storage element 12 are in contact with each other, and the top surface 140 of the second energy storage element 12 and the top surface 140 of the third energy storage element 13 are in contact with each other. Such a structure allows the energy storage elements 10 to be spaced close to each other, thereby enabling the energy storage element group 41 to be miniaturized in the Z-axis direction. In order to ensure electrical insulation between the energy storage elements 10, insulating spacers may be interposed between the elements.

[0076] Specifically, each energy storage element 10 includes a first positive terminal 310a, a second positive terminal 310b, a first negative terminal 320a, and a second negative terminal 320b as terminals 300. In the first side surface portion 110 of each energy storage element 10, the first negative terminal 320a is provided on the first upper surface 112 of the first recess 101, and the first positive terminal 310a is provided on the first lower surface 114 of the second recess 102. In the second side surface portion 120, the second positive terminal 310b is provided on the second upper surface 122 of the first recess 101, and the second negative terminal 320b is provided on the second lower surface 124 of the second recess 102. Thus, the first negative terminal 320a and the second positive terminal 310b arranged in the two first recesses 101 in the energy storage element 10 have different polarities. Similarly, the first positive terminal 310a and the second negative terminal 320b arranged in the two second recesses 102 have different polarities.

[0077] In the present embodiment, the first positive electrode terminal 310a and the first negative electrode terminal 320a are an example of two one-end terminals arranged at one end (first side surface portion 110) of the energy storage element 10 in the X-axis direction. That is, the two one-end terminals (first positive electrode terminal 310a and first negative electrode terminal 320a) have different polarities. Furthermore, it can be said that the two one-end terminals are arranged on both surfaces (first upper surface 112 and first lower surface 114) of the first side surface portion 110 in the Z-axis direction.

[0078] Similarly, the second positive electrode terminal 310b and the second negative electrode terminal 320b are examples of two other end terminals arranged at the other end (second side surface portion 120) of the energy storage element 10 in the X-axis direction. In other words, the two other end terminals (second positive electrode terminal 310b and second negative electrode terminal 320b) have different polarities. Furthermore, it can be said that the two other end terminals are arranged on both surfaces (second upper surface 122 and second lower surface 124) of the second side surface portion 120 in the Z-axis direction.

[0079] The first storage element 11 and the third storage element 13 are disposed in a position where the first negative electrode terminal 320a and the second positive electrode terminal 310b face in the positive direction of the Z axis, and the first positive electrode terminal 310a and the second negative electrode terminal 320b face in the negative direction of the Z axis. In contrast, the second storage element 12 is disposed in a position where the first negative electrode terminal 320a and the second positive electrode terminal 310b face in the negative direction of the Z axis, and the first positive electrode terminal 310a and the second negative electrode terminal 320b face in the positive direction of the Z axis.

[0080] Therefore, the first positive electrode terminal 310a of the first energy storage element 11 and the first positive electrode terminal 310a of the second energy storage element 12 face each other in the Z-axis direction. These two first positive electrode terminals 310a are electrically connected to each other by a bus bar 42. Specifically, an end of the bus bar 42 facing the positive direction of the Z-axis is joined to the first positive electrode terminal 310a of the first energy storage element 11, and an end of the bus bar 42 facing the negative direction of the Z-axis is joined to the first positive electrode terminal 310a of the second energy storage element 12. The bus bar 42 is accommodated in a space S formed by the first recess 102 in the first side surface portion 110 of the first energy storage element 11 and the second recess 102 in the first side surface portion 110 of the second energy storage element 12. In particular, from the perspective of saving space, it is preferable that the bus bar 42 have a shape that does not protrude from the outer shapes of the first energy storage element 11 and the second energy storage element 12 when viewed in the Z-axis direction. Within the space S, a surplus space is formed between both ends of the bus bar 42. By inserting a terminal joining tool or the like into this surplus space, a smooth joining operation can be performed.

[0081] Similarly, the second negative electrode terminal 320b of the first energy storage element 11 and the second negative electrode terminal 320b of the second energy storage element 12 face each other in the Z-axis direction. These two second negative electrode terminals 320b are electrically connected to each other by a bus bar 42. In this manner, the first energy storage element 11 and the second energy storage element 12 are electrically connected in parallel.

[0082] Next, the electrical connection structure between second power storage element 12 and third power storage element 13 will be described.

[0083] The first negative electrode terminal 320a of the second energy storage element 12 and the first negative electrode terminal 320a of the third energy storage element 13 face each other in the Z-axis direction. These two first negative electrode terminals 320a are electrically connected to each other by a bus bar 42. Similarly, the second positive electrode terminal 310b of the second energy storage element 12 and the second positive electrode terminal 310b of the third energy storage element 13 face each other in the Z-axis direction. These two second positive electrode terminals 310b are electrically connected to each other by a bus bar 42. In this way, the second energy storage element 12 and the third energy storage element 13 are electrically connected in parallel.

[0084] As a result, in the energy storage element group 41 in one energy storage unit 4, the plurality of energy storage elements 10 are electrically connected in parallel.

[0085] [Electrical connection between energy storage units] Fig. 7 is a perspective view showing a portion of a plurality of energy storage units 4 according to an embodiment in an expanded state. Fig. 7 shows four energy storage units 4 from the end in the negative Y-axis direction out of the plurality of energy storage units 4 arranged in a row. For ease of explanation, Fig. 7 shows the polarity of each terminal 300 arranged at both ends in the Z-axis direction of the energy storage element group 41 of each energy storage unit 4 with a mark ("+" for positive electrode, "-" for negative electrode).

[0086] Here, the energy storage units 4 are of the same type, and when numbered sequentially from the end in the negative direction of the Y axis, odd-numbered energy storage units 4 are arranged in the same orientation, while even-numbered energy storage units 4 are arranged in an orientation inverted in the Z axis direction. That is, in the odd-numbered energy storage units 4, the first negative electrode terminal 320a and the second positive electrode terminal 310b of the first energy storage element 11 face in the positive direction of the Z axis, and the first positive electrode terminal 310a and the second negative electrode terminal 320b of the third energy storage element 13 face in the negative direction of the Z axis (the orientation shown in FIG. 6). On the other hand, in the even-numbered energy storage units 4, the first positive electrode terminal 310a and the second negative electrode terminal 320b of the third energy storage element 13 face in the positive direction of the Z axis, and the first negative electrode terminal 320a and the second positive electrode terminal 310b of the first energy storage element 11 face in the negative direction of the Z axis (the orientation is upside down from FIG. 6).

[0087] Two adjacent energy storage units 4 in the Y-axis direction are electrically connected in series by a plurality of bus bars 29. Specifically, the electrical connection (first connection structure) between the first energy storage unit 4 and the second energy storage unit 4 will be described. The first negative electrode terminal 320a of the first energy storage element 11 in the first energy storage unit 4 and the first positive electrode terminal 310a of the third energy storage element 13 in the second energy storage unit 4 are electrically connected by the bus bar 29. The second negative electrode terminal 320b of the third energy storage element 13 in the first energy storage unit 4 and the second positive electrode terminal 310b of the first energy storage element 11 in the second energy storage unit 4 are electrically connected by the bus bar 29. In this manner, the energy storage elements 10 at the ends of the first energy storage unit 4 and the second energy storage unit 4 are electrically connected to each other in the Z-axis direction. As a result, the first energy storage unit 4 and the second energy storage unit 4 are connected in series to an electric body.

[0088] Next, the electrical connection (second connection structure) between the second energy storage unit 4 and the third energy storage unit 4 will be described. The second negative electrode terminal 320b of the third energy storage element 13 in the second energy storage unit 4 and the second positive electrode terminal 310b of the first energy storage element 11 in the third energy storage unit 4 are electrically connected by a bus bar 29. The first negative electrode terminal 320a of the first energy storage element 11 in the second energy storage unit 4 and the first positive electrode terminal 310a of the third energy storage element 13 in the third energy storage unit 4 are electrically connected by a bus bar 29. In this manner, the second energy storage unit 4 and the third energy storage unit 4 are electrically connected at the energy storage elements 10 at their ends in the Z-axis direction. As a result, the second energy storage unit 4 and the third energy storage unit 4 are connected in series to an electric body.

[0089] The first connection structures and the second connection structures are alternately repeated in the Y-axis direction, so that a row of multiple energy storage units 4 is electrically connected in series. Of the multiple energy storage units 4 in a row, in the energy storage units 4 at both ends in the Y-axis direction, the terminals 300 that are not connected to other energy storage units 4 are electrically connected in series to the positive external terminal and the negative external terminal via an external terminal bus bar (not shown) or the like. This makes it possible to easily electrically connect the energy storage device 1 to an external device via the positive external terminal and the negative external terminal, even when multiple energy storage units 4 are housed in the case 2.

[0090] 7, the length of bus bar 29 in the Y-axis direction is illustrated as being longer than the actual length in order to accommodate each of the deployed energy storage units 4, but in reality, the length of bus bar 29 only needs to be long enough to electrically connect two adjacent energy storage units 4 stacked in the Y-axis direction. Therefore, the length of bus bar 29 can be made shorter than the length (width) of two energy storage units 4 in the Y-axis direction.

[0091] [Effect description] As described above, according to the embodiment of the present invention, it is possible to configure a tall energy storage device 1 required for a mobile or stationary power source using low-profile energy storage elements 10 produced as a power source for a passenger car-sized electric vehicle, and it is possible to provide an energy storage device 1 that is suitable for reusing low-profile energy storage elements 10. This makes it possible to suppress a decrease in the energy density of the system and also to suppress an increase in costs.

[0092] In each energy storage element 10, one end terminal in the positive Z-axis direction (first negative electrode terminal 320a) and the other end terminal in the positive Z-axis direction (second positive electrode terminal 310b) have different polarities, and one end terminal in the negative Z-axis direction (first positive electrode terminal 310a) and the other end terminal in the negative Z-axis direction (second negative electrode terminal 320b) have different polarities. This allows multiple energy storage elements 10 lined up in the Z-axis direction to be easily connected in parallel.

[0093] The two one-end terminals of the energy storage element 10 are the first positive electrode terminal 310a and the first negative electrode terminal 320a, and the two other-end terminals are the second positive electrode terminal 310b and the second negative electrode terminal 320b, so when connecting the one-end terminals of two energy storage elements 10 adjacent in the Z-axis direction, the positive electrode terminals or the negative electrode terminals can be connected (connected in parallel). The same applies to the other-end terminals.

[0094] By arranging the one end terminals on both surfaces in the Z-axis direction of the first side surface portion 110 of the energy storage element 10 (the first upper surface 112 and the first lower surface 114), the length of the bus bar 42 electrically connecting the one end terminals of the two energy storage elements 10 can be made shorter. Similarly, by arranging the other end terminals on both surfaces in the Z-axis direction of the second side surface portion 120 of the energy storage element 10 (the second upper surface 122 and the second lower surface 124), the length of the bus bar 42 electrically connecting the other end terminals of the two energy storage elements 10 can be made shorter.

[0095] Since the plurality of energy storage element groups 41 are stacked in the Y-axis direction (stacking direction), it is possible to form a compact energy storage device 1. Furthermore, among the plurality of energy storage element groups 41 stacked in the Y-axis direction, in two adjacent energy storage element groups 41, the energy storage elements 10 at the ends in the Z-axis direction are electrically connected in series, so the length of the bus bar 29 connecting the adjacent energy storage element groups 41 can be shortened.

[0096] Each energy storage element 10 has notches (first recess 101, second recess 102) at both ends in the Z-axis direction of the first side surface portion 110 (one end), and also has notches (first recess 101, second recess 102) at both ends in the Z-axis direction of the second side surface portion 120. Terminal 300 and bus bars (bus bar 29 and bus bar 42) connected to terminal 300 can be arranged inside each notch, thereby achieving space savings.

[0097] [Description of Modifications] The following describes various modifications of the above embodiment. In the following description, the same parts as those in the above embodiment or other modifications are designated by the same reference numerals, and the description thereof may be omitted.

[0098] (Variation 1) Modification 1 of the above embodiment will be described. In the above embodiment, the case where the two one-end terminals (first positive terminal 310a and first negative terminal 320a) arranged on the first side surface portion 110 have different polarities and the two other-end terminals (second positive terminal 310b and second negative terminal 320b) arranged on the second side surface portion 120 have different polarities is exemplified. In this modification 1, the case where the two one-end terminals have the same polarity and the two other-end terminals have the same polarity is exemplified.

[0099] FIG. 8 is a plan view showing a storage element group 41C according to Modification 1. FIG. 8 is a view corresponding to FIG. 6. As shown in FIG. 8, the three storage elements 10c constituting the storage element group 41C are arranged side by side in the Z-axis direction. Here, the storage element 10c in the positive direction of the Z-axis is referred to as a first storage element 11c, the storage element 10c in the negative direction of the Z-axis is referred to as a third storage element 13c, and the storage element 10c therebetween is referred to as a second storage element 12c. The first storage element 11c, the second storage element 12c, and the third storage element 13c are all of the same type.

[0100] Specifically, each energy storage element 10c includes a first positive terminal 310a, a second positive terminal 310b, a first negative terminal 320a, and a second negative terminal 320b as terminals 300. In the first side surface portion 110 of each energy storage element 10c, the first negative terminal 320a is provided on the first upper surface 112 of the first recess 101, and the second negative terminal 320b is provided on the first lower surface 114 of the second recess 102. In the second side surface portion 120, the second positive terminal 310b is provided on the second upper surface 122 of the first recess 101, and the first positive terminal 310a is provided on the second lower surface 124 of the second recess 102. Thus, the first negative terminal 320a and the second positive terminal 310b arranged in the two first recesses 101 in the energy storage element 10c have different polarities. Similarly, the first positive electrode terminal 310a and the second negative electrode terminal 320b arranged in the two second recesses 102 have different polarities. Furthermore, the two one-end terminals (the first negative electrode terminal 320a and the second negative electrode terminal 320b) arranged in the first side surface portion 110 have the same polarity. Similarly, the two other-end terminals (the first positive electrode terminal 310a and the second positive electrode terminal 310b) arranged in the second side surface portion 120 have the same polarity.

[0101] The first storage element 11c, the second storage element 12c, and the third storage element 13c are arranged in such a manner that the first negative electrode terminal 320a and the second positive electrode terminal 310b face in the positive direction of the Z axis, and the first positive electrode terminal 310a and the second negative electrode terminal 320b face in the negative direction of the Z axis.

[0102] Therefore, second negative electrode terminal 320b of first power storage element 11c and first negative electrode terminal 320a of second power storage element 12c face each other in the Z-axis direction. These two second negative electrode terminals 320b and first negative electrode terminal 320a are electrically connected by bus bar 42.

[0103] Similarly, the first positive electrode terminal 310a of the first energy storage element 11c and the second positive electrode terminal 310b of the second energy storage element 12c face each other in the Z-axis direction. These two first positive electrode terminals 310a and the second positive electrode terminals 310b are electrically connected by the bus bar 42. In this manner, the first energy storage element 11c and the second energy storage element 12c are electrically connected in parallel. A similar electrical connection is also made between the second energy storage element 12c and the third energy storage element 13c, so that the second energy storage element 12c and the third energy storage element 13c are electrically connected in parallel. As a result, in the energy storage element group 41C, the multiple energy storage elements 10c are electrically connected in parallel.

[0104] Thus, the two one-end terminals of the energy storage element 10c are the first negative electrode terminal 320a and the second negative electrode terminal 320b, and the two other-end terminals are the first positive electrode terminal 310a and the second positive electrode terminal 310b. For this reason, two energy storage elements 10c adjacent in the Z-axis direction can be connected in parallel by connecting the negative electrode terminals together when connecting the one-end terminals of the elements 10c and connecting the positive electrode terminals together when connecting the other-end terminals of the elements 10c.

[0105] (Variation 2) In the above embodiment, an energy storage device 10 including a container 100 with flat top surface 140 and bottom surface 150 has been exemplified. In this modified example 2, an energy storage device including a container with curved top surface and bottom surface will be described. Fig. 9 is an exploded perspective view showing the components of an energy storage device 10d according to modified example 2. Fig. 9 is a view corresponding to Fig. 4.

[0106] As shown in FIG. 9, the container 100d is a case having an outer shape based on an oval cylinder that is elongated in the X-axis direction and flattened in the Y-axis direction. In this container 100d, both end faces opposing each other in the Y-axis direction are long side faces 130. Each long side face 130 is a flat surface parallel to the XZ plane and elongated in the X-axis direction, and both end portions in the X-axis direction have shapes corresponding to the first side face portion 110 and the second side face portion 120. Of the both end faces opposing each other in the Z-axis direction in the container 100d, the end face facing the positive Z-axis direction is the top face 140d, and the end face facing the negative Z-axis direction is the bottom face 150d. The top face 140d is a curved surface elongated in the X-axis direction and protruding in the positive Z-axis direction. The bottom face 150d is a curved surface elongated in the X-axis direction and protruding in the negative Z-axis direction.

[0107] The container 100d has a container body 160d and a pair of lids 170d, and is formed into an elongated cylindrical shape by assembling the container body 160d and each lid 170d. The container body 160d is formed into an elongated cylindrical shape that penetrates in the X-axis direction.

[0108] The pair of lids 170d are members that seal both ends of the container body 160d in the X-axis direction. One of the lids 170d seals the end of the container body 160d in the positive direction of the X-axis. One of the lids 170d is formed from a metal plate and is bent to correspond to the shape of the end of the container body 160d in the negative direction of the X-axis. One of the lids 170d has 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 other lid 170d seals the end of the container body 160d in the negative direction of the X-axis. The other lid 170d is formed from a metal plate and is bent to correspond to the shape of the end of the container body 160d in the positive direction of the X-axis. The other cover 170d has a second upper side surface 121, a second top surface 122, a second middle side surface 123, a second bottom surface 124, and a second bottom side surface 125.

[0109] With this configuration, the container 100d has a structure in which the electrode assembly 700 and the like are housed inside the container body 160d, and then the container body 160d and the lid 170d are joined by welding or the like, thereby sealing the interior.

[0110] When arranging a plurality of energy storage elements 10d in the Z-axis direction to form an energy storage element group 41D, a spacer 900d may be disposed between two adjacent energy storage elements 10d in the Z-axis direction. FIG. 10 is an explanatory diagram showing a spacer 900d provided in an energy storage element group 41D according to Modification 2. FIG. 10 is a diagram showing two adjacent energy storage elements 10d in the Z-axis direction and the spacer 900d as viewed from the X-axis direction. As shown in FIG. 10, the spacer 900d is sandwiched between the two energy storage elements 10d. Specifically, the spacer 900d is sandwiched between a bottom surface 150d of the energy storage element 10d in the positive direction of the Z-axis and a top surface 140d of the energy storage element 10d in the negative direction of the Z-axis. The spacer 900d is formed from an insulating material such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), ABS resin, or a composite material thereof.

[0111] The spacer 900d is a rod-shaped member that is long in the X-axis direction. The surface of the spacer 900d facing the positive Z-axis direction is a first concave curved surface 910d that is recessed in a concave curved shape corresponding to the bottom surface 150d. Meanwhile, the surface of the spacer 900d facing the negative Z-axis direction is a second concave curved surface 920d that is recessed in a concave curved shape corresponding to the top surface 140d. The first concave curved surface 910d and the second concave curved surface 920d are uniformly formed over the entire length of the spacer 900d in the X-axis direction. The bottom surface 150d is fitted into the first concave curved surface 910d, and the top surface 140d is fitted into the second concave curved surface 920d. This allows the spacer 900d to stably hold two energy storage elements 10d that are adjacent in the Z-axis direction.

[0112] (Other variations) Although the present invention has been described above with reference to an embodiment of the power storage device, the present invention is not limited to the above embodiment. The embodiment disclosed herein is illustrative in all respects, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

[0113] For example, in the above embodiment, the case where only one electrode body 700 is housed in the container 100 has been exemplified, but a plurality of electrode bodies may be housed in the container.

[0114] In the above embodiment, a wound electrode assembly 700 is exemplified. However, the shape of the electrode assembly is not limited to the wound type, and it may be a stack type in which flat electrode plates are stacked, or a shape in which the electrode plates and / or separators are folded bellows-like. Specific examples of the latter include a type in which a separator is folded bellows-like to sandwich a rectangular electrode plate, or a type in which the electrode plate and separator are stacked and then folded bellows-like. A bipolar electrode assembly is also possible.

[0115] In the above embodiment, the power storage device 1 is illustrated as including a plurality of power storage units 4. However, the power storage device may include at least one power storage unit, and any number of power storage units may be installed.

[0116] In the above embodiment, the terminal mounting surface is the first upper surface 112, the first lower surface 114, the second upper surface 122, or the second lower surface 124. However, the first upper side surface, the first lower side surface, the second upper side surface, or the second lower side surface may be the terminal mounting surface. In this case, the terminals on the first side surface portion face in the positive direction of the X-axis, and the terminals on the second side surface portion face in the negative direction of the X-axis.

[0117] In the above embodiment, the energy storage element 10 is exemplified as having four cutouts (first recess 101 and second recess 102). However, any number of cutouts may be provided, and no cutouts may be provided.

[0118] The terminals provided on each of the energy storage elements may be bolt terminals. At least a portion of the cutout portion (first recess and second recess) may be cut out in a curved shape.

[0119] In the above embodiment, the case where the multiple energy storage units 4 are of the same type has been exemplified. Here, energy storage units of the same type refer to an energy storage unit and another energy storage unit to be compared having the same or similar overall shape. Not all of the components constituting the energy storage units need to be similar. It is sufficient that the arrangement of the terminals (positive terminal, negative terminal) in one energy storage unit is the same as the arrangement of the terminals (positive terminal, negative terminal) in another energy storage unit to be compared. In this case, if the arrangement of the terminals in one energy storage unit is the same as the arrangement of the terminals in the other energy storage unit when one of the energy storage units is rotated up and down or left and right, it can be said that the two are of the same type. The same applies to energy storage elements.

[0120] In the above embodiment, the power storage unit 4 is illustrated as including the protective cover 43 and the holder 44. However, the power storage unit does not necessarily have to include at least one of the protective cover and the holder.

[0121] In the above embodiment, an example has been given in which all the energy storage elements 10 in each energy storage element group 41 have four terminals 300. However, in some of the energy storage elements 10, electrical connection as an energy storage device may be completed in a state in which one or more of the four terminals 300 are unused. In this case, the terminals that are not connected to the connection target do not need to be provided on the energy storage elements.

[0122] Any combination of the components included in the above-described embodiments and their modifications is also included within the scope of the present invention. [Industrial Applicability]

[0123] The present invention can be applied to an electricity storage device including an electricity storage element such as a lithium ion secondary battery. [Explanation of symbols]

[0124] 1. Energy storage device 2 cases 4 Energy storage unit 10, 10c, 10d Energy storage element 11, 11c First storage element 12, 12c Second storage element 13, 13c Third storage element 29, 42 busbars 41, 41C, 41D Storage element group 100, 100d container 101 First recess (notch) 102 Second recess (notch) 110 First side part (one end part) 300 terminals 310a First positive terminal 310b Second positive terminal 320a First negative terminal 320b Second negative terminal 700 Electrode body

Claims

1. a plurality of storage elements each having a container based on a rectangular parallelepiped; The length (L) of the rectangular parallelepiped in the longitudinal direction, the length (H) of the rectangular parallelepiped in the height direction, and the length (T) of the rectangular parallelepiped satisfy the relationship L>H>T, The container has four terminals, two positive terminals and two negative terminals, at both ends in the longitudinal direction; two one-end terminals, which are two terminals of the four terminals, are arranged at one end in the longitudinal direction, and two other-end terminals, which are the other two terminals of the four terminals, are arranged at the other end in the longitudinal direction; the plurality of energy storage elements are arranged in the height direction to form an energy storage element group, two adjacent storage elements in the height direction among the plurality of storage elements have one of the one end terminals electrically connected to each other and one of the other end terminals electrically connected to each other, The plurality of energy storage element groups are stacked in the width direction and electrically connected. Energy storage device.

2. one end terminal on one side in the height direction of the two one end terminals and the other end terminal on the one side in the height direction of the two other end terminals have different polarities; The one end terminal on the other side in the height direction of the two one end terminals and the other end terminal on the other side in the height direction of the two other end terminals have different polarities. The power storage device according to claim 1 .

3. the two one-end terminals are one of the two positive electrode terminals and one of the two negative electrode terminals, The two other end terminals are the other of the two positive electrode terminals and the other of the two negative electrode terminals. The electricity storage device according to claim 1 or 2.

4. the two one-end terminals are arranged on both sides of the one end in the height direction, The two other end terminals are disposed on both sides of the other end in the height direction. The electricity storage device according to claim 1 or 2.

5. In two of the plurality of storage element groups adjacent to each other in the width direction, the storage elements at the ends in the height direction are electrically connected in series. The electricity storage device according to claim 1 or 2.

6. Each of the plurality of energy storage elements has a notch on both sides of the one end in the height direction, in which the two one end terminals are arranged, and a notch on both sides of the other end in the height direction, in which the two other end terminals are arranged. The electricity storage device according to claim 1 or 2.

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