Power storage device

Abstract

This power storage device is provided with a power storage element group in which X power storage elements arranged in a first direction are electrically connected in parallel. An N power storage element, which is a power storage element disposed at the N-th place counting from a first power storage element that is a power storage element of a terminal in the first direction, comprises, as first direction end parts: a (2N -1) end part at which a (2N -1) positive electrode terminal and a (2N-1) negative electrode terminal are disposed; and a (2N) end part at which a (2N) positive electrode terminal and a (2N) negative electrode terminal are disposed. A (N+1) power storage element adjacent to the N power storage element comprises, as first direction end parts: a (2N+1) end part at which a (2N+1) positive electrode terminal and a (2N+1) negative electrode terminal are disposed; and a (2N+2) end part at which a (2N+2) positive electrode terminal and a (2N+2) negative electrode terminal are disposed. The (2N) end part and the (2N+1) end part are opposing in the first direction. The (2N) positive electrode terminal and the (2N+1) positive electrode terminal are electrically connected. The (2N) negative electrode terminal and the (2N +1) negative electrode terminal are electrically connected.

Description

Power storage device

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

[0002] Conventionally, a method has been proposed for improving the energy density of a battery pack by storing a large number of long batteries in the battery pack and minimizing excess space within the battery pack (see, for example, Patent Document 1). Furthermore, a method has been proposed for constructing a long battery by storing a plurality of electrode body sets connected in series within the container of the long battery. Furthermore, a battery pack constructed by connecting a large number of such long batteries has also been proposed (see, for example, Patent Document 2).

[0003] Patent No. 7197689 Patent No. 7338055

[0004] To improve the energy density of batteries, it is necessary to increase the length of battery cells or battery modules that include them. However, if individual battery cells are made longer, the longer the length, the more difficult it becomes to manufacture them.

[0005] Therefore, an object of the present invention is to provide an electricity storage device in which the battery module can be easily elongated.

[0006] An energy storage device according to one aspect of the present invention includes a group of energy storage elements in which X energy storage elements are arranged in a first direction and electrically connected in parallel, and an N-th energy storage element, which is an energy storage element arranged Nth (N is a natural number, and 1≦N≦X−1) from a first energy storage element that is an end energy storage element in the first direction, includes, as end portions in the first direction, a (2N−1)-th end portion where a (2N−1)-th positive electrode terminal and a (2N−1)-th negative electrode terminal are arranged, and a (2N)-th end portion where a (2N)-th positive electrode terminal and a (2N)-th negative electrode terminal are arranged, and The (N+1)th storage element adjacent to the N storage element has, as ends in the first direction, a (2N+1)th end where a (2N+1)th positive electrode terminal and a (2N+1)th negative electrode terminal are arranged, and a (2N+2)th end where a (2N+2)th positive electrode terminal and a (2N+2)th negative electrode terminal are arranged, the (2N) end and the (2N+1) end face each other in the first direction, the (2N) positive electrode terminal and the (2N+1) positive electrode terminal are electrically connected, and the (2N) negative electrode terminal and the (2N+1) negative electrode terminal are electrically connected.

[0007] According to the present invention, it is possible to provide an electricity storage device in which the length of an electricity storage element group can be easily increased.

[0008] FIG. 1 is a perspective view showing the appearance of an energy storage device according to an embodiment. FIG. 2 is an exploded perspective view showing each component when the energy storage device according to the embodiment is disassembled. FIG. 3 is a perspective view showing the appearance of an energy storage element according to the embodiment. FIG. 4 is an exploded perspective view showing each component when the energy storage element according to the embodiment is disassembled. FIG. 5 is a perspective view showing the configuration of an electrode body according to the embodiment. FIG. 6 is a plan view showing an energy storage element group according to the embodiment. FIG. 7 is an exploded perspective view showing a plurality of energy storage element groups according to the embodiment. FIG. 8 is an exploded perspective view showing a plurality of energy storage element groups according to Modification 1. FIG. 9 is an exploded perspective view showing a plurality of energy storage element groups according to Modification 2. FIG. 10 is an exploded perspective view showing a plurality of energy storage element groups according to Modification 3. FIG. 11 is an exploded perspective view showing each component when the energy storage element according to Modification 4 is disassembled. FIG. 12 is a plan view showing an energy storage element group according to Modification 5. FIG. 13A is a top view showing an intra-energy storage element group bus bar according to Modification 6. FIG. 13B is a perspective view showing an inter-energy storage element group bus bar according to Modification 6.

[0009] (1) An energy storage device according to one aspect of the present invention includes a group of energy storage elements in which X energy storage elements are arranged in a first direction and electrically connected in parallel, and an N-th energy storage element, which is an energy storage element arranged Nth (N is a natural number, and 1≦N≦X−1) from a first energy storage element that is an end energy storage element in the first direction, includes, as ends in the first direction, a (2N−1)-th end where a (2N−1)-th positive terminal and a (2N−1)-th negative terminal are arranged, and a (2N)-th end where a (2N)-th positive terminal and a (2N)-th negative terminal are arranged, The (N+1)th storage element adjacent to the Nth storage element has, as ends in the first direction, a (2N+1)th end where a (2N+1)th positive electrode terminal and a (2N+1)th negative electrode terminal are arranged, and a (2N+2)th end where a (2N+2)th positive electrode terminal and a (2N+2)th negative electrode terminal are arranged, the (2N) end and the (2N+1) end face each other in the first direction, the (2N) positive electrode terminal and the (2N+1) positive electrode terminal are electrically connected, and the (2N) negative electrode terminal and the (2N+1) negative electrode terminal are electrically connected.

[0010] According to the energy storage device described in (1) above, for example, when X is 2 and N is 1, the second end and third end of the first and second energy storage elements adjacent to each other in the first direction face each other in the first direction, the second positive terminal and the third positive terminal are electrically connected, and the second negative terminal and the third negative terminal are electrically connected. In other words, the first and second energy storage elements arranged in the first direction can be electrically connected in parallel, allowing the energy storage element group as a whole to be elongated in the first direction. This makes it easier to manufacture an energy storage element group that is elongated in the first direction, compared to when each energy storage element is individually elongated in the first direction. Furthermore, when adjacent energy storage elements are connected in parallel, the length of the bus bar connecting the terminals can be shortened.

[0011] (2) In the energy storage device described in (1) above, the energy storage device may include x energy storage element groups, and the x energy storage element groups may be arranged along a third direction that is perpendicular to both the first direction and a second direction that is the arrangement direction of the (2N) positive electrode terminals and the (2N) negative electrode terminals, and an n-th energy storage element group that is the n-th energy storage element group (n is a natural number and 1≦n≦x−1) that is located n-th from a first energy storage element group that is the end energy storage element group in the third direction, and an (n+1)-th energy storage element group adjacent to the n-th energy storage element group may be electrically connected in series.

[0012] According to the energy storage device described in (2) above, the nth energy storage element group and the (n+1)th energy storage element group are electrically connected in series while being arranged along the third direction, which makes it possible to make the energy storage device compact. Furthermore, when adjacent energy storage element groups are connected in series, the length of the bus bars joining the terminals can be shortened.

[0013] (3) In the energy storage device described in (2) above, the arrangement of the first positive electrode terminal and the first negative electrode terminal of the first energy storage element included in the nth energy storage element group may be an arrangement obtained by flipping the arrangement of the first positive electrode terminal and the first negative electrode terminal of the first energy storage element included in the (n+1)th energy storage element group in the second direction, and the arrangement of the (2X)th positive electrode terminal and the (2X)th negative electrode terminal of the Xth energy storage element included in the nth energy storage element group may be an arrangement obtained by flipping the arrangement of the (2X)th positive electrode terminal and the (2X)th negative electrode terminal of the Xth energy storage element included in the (n+1)th energy storage element group in the second direction.

[0014] According to the energy storage device described in (3) above, for example, when X is 2 and n is 1, the arrangement of the first positive electrode terminals and the first negative electrode terminals of the first energy storage elements included in the first energy storage element group is the reverse of the arrangement of the first positive electrode terminals and the first negative electrode terminals of the first energy storage elements included in the second energy storage element group in the second direction. Similarly, the arrangement of the fourth positive electrode terminals and the fourth negative electrode terminals of the second energy storage elements included in the first energy storage element group is the reverse of the arrangement of the fourth positive electrode terminals and the fourth negative electrode terminals of the second energy storage elements included in the second energy storage element group in the second direction. In other words, the first energy storage element group and the second energy storage element group can be made to have the same type. Therefore, the first energy storage element group and the second energy storage element group can have a common structure.

[0015] (4) The energy storage device described in (2) or (3) above may include a positive external terminal, a negative external terminal, and a housing that houses x groups of energy storage elements, and the positive external terminal and the negative external terminal may be electrically connected to the x groups of energy storage elements that are connected in series.

[0016] According to the energy storage device described in (4) above, the positive and negative external terminals of the housing are electrically connected to the x energy storage element groups. Therefore, even when the x energy storage element groups are housed in the housing, electrical connection with an external device can be easily made via the positive and negative external terminals.

[0017] (5) In the energy storage device described in any one of (1) to (4) above, the (2N-1) end may include a (2N-1) positive electrode notch in which the (2N-1) positive electrode terminal is disposed, and a (2N-1) negative electrode notch in which the (2N-1) negative electrode terminal is disposed, and the (2N) end may include a (2N) positive electrode notch in which the (2N) positive electrode terminal is disposed, and a (2N) negative electrode notch in which the (2N) negative electrode terminal is disposed.

[0018] According to the energy storage device described in (5) above, for example, when N is 1, a first positive electrode terminal is disposed in the first positive electrode notch, a first negative electrode terminal is disposed in the first negative electrode notch, a second positive electrode terminal is disposed in the second positive electrode notch, and a second negative electrode terminal is disposed in the second negative electrode notch. This allows at least a portion of the conductive member (such as a bus bar) connected to each terminal to be disposed within the notch. This makes it difficult for the conductive member to protrude outward from the energy storage element, thereby reducing the space consumed outside the energy storage element.

[0019] (Embodiments) Hereinafter, with reference to the drawings, a description will be given of an energy storage device and an energy storage element according to embodiments of the present invention (including modified examples 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 or similar components are assigned the same reference numerals. 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.

[0020] In the following description and drawings, the X-axis direction is defined as the arrangement direction of multiple energy storage elements included in one energy storage element group, the protruding direction of the tab portion, and the direction along the winding axis of the electrode body provided in the energy storage element. The Y-axis direction is defined as the arrangement direction of multiple energy storage element groups, the stacking direction of the electrode plates on the flat portion of the electrode body, and the thickness direction of the container of the energy storage element. The Z-axis direction is defined as the arrangement direction of the case lid and case body of the energy storage device, the up-down direction, and the opposing direction of the pair of curved portions of the electrode body. The X-axis direction is an example of a first direction, the Y-axis direction is an example of a third direction, and the Z-axis direction is an example of a second direction. The X-axis direction, Y-axis direction, and Z-axis direction intersect each other (orthogonal in this embodiment). Depending on the usage mode, the Z-axis direction may not be the up-down direction; however, for convenience of explanation, the Z-axis direction will be described below as the up-down direction.

[0021] In the following description, for example, the positive X-axis direction indicates the direction of the X-axis arrow, and the negative X-axis direction indicates the direction opposite to the positive X-axis direction. The same applies to the Y-axis and Z-axis directions. Furthermore, expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the directions or attitudes are not strictly those of the same kind. For example, saying that two directions are perpendicular does not only mean that the two directions are completely perpendicular, but also means that the directions are substantially perpendicular, i.e., there is a difference of, for example, a few percent.

[0022] In the following description, the term "insulation" means "electrical insulation." An insulating material has a volume resistivity of 1×10 １０ It is preferable that the material be made of a material with a resistance of Ωm or more.

[0023] [Description of Energy Storage Device] First, a schematic configuration of an energy storage device 1 according to the present embodiment will be described. Fig. 1 is a perspective view showing the appearance of the energy storage device 1 according to the embodiment. Fig. 2 is an exploded perspective view showing each component of the energy storage device 1 according to the embodiment when disassembled. The energy storage device according to the present embodiment will be exemplified by a case where X is 2 and x is 4, but is not limited to this.

[0024] The power storage device 1 is a device capable of charging with electricity from an external source or discharging electricity to an external source. In this embodiment, the power storage device 1 has a substantially rectangular parallelepiped shape. The rectangular parallelepiped here refers to a hexahedron with all sides formed as rectangles or squares. The power storage device 1 is a battery module (battery assembly) used for power storage, power supply, or other purposes. Specifically, the power storage device 1 is used as a battery for driving or starting the engine of a moving object such as an automobile, motorcycle, personal watercraft, ship, snowmobile, agricultural machinery, construction machinery, automatic guided vehicle (AGV), or electric railway vehicle. Examples of the automobile include an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicle. Examples of the electric railway vehicle include a train, a monorail, a linear motor car, and a hybrid train equipped with both a diesel engine and an electric motor. The power storage device 1 can also be used as a stationary battery for home or business use.

[0025] As shown in Fig. 1 , the energy storage device 1 includes a case 2. As shown in Fig. 2 , the case 2 accommodates a plurality of energy storage element groups 90, a plurality of spacers 20, a plurality of bus bars 25, and the like. The energy storage device 1 also includes external terminals (a positive electrode external terminal 28 and a negative electrode external terminal 29) for electrically connecting to an external device. In addition to the above components, the energy storage device 1 may also include restraining members (end plates, side plates, etc.) that restrain the plurality of energy storage elements 10, a bus bar holder that holds the bus bars 25, 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, and an exhaust member that forms an exhaust path for gas discharged from each energy storage element 10.

[0026] 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 elements 10 and the plurality of spacers 20, etc., and fixes the plurality of energy storage elements 10 and the plurality of spacers 20, etc., in predetermined positions to protect them from impacts and the like. The case 2 is a metal case formed from a metal member such as aluminum, aluminum alloy, stainless steel, iron, or plated steel sheet. The case 2 may be formed from an insulating material such as any of the resin materials that can be used for the spacers 20 described below. If the case 2 is formed from 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.

[0027] 2, the case 2 has a case main body 30 that forms the main body of the case 2, and a case lid 40 that forms the lid of the case 2. The case main body 30 is a rectangular cylindrical housing (chassis) with a bottom and an opening 31 formed in the positive direction of the Z axis, and houses a plurality of energy storage elements 10, a plurality of spacers 20, etc.

[0028] Specifically, the case body 30 has a bottom wall 32 and a side wall 33. The bottom wall 32 is a flat, rectangular portion located at the end of the case body 30 in the negative Z-axis direction. The side wall 33 is a rectangular, annular wall extending from the outer periphery in the positive Z-axis direction, and is provided continuously around the entire circumference of the bottom wall 32. The opening 31 is located inside the side wall 33. The case body 30 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.

[0029] The case lid 40 is a flat, rectangular member that closes the rectangular opening 31 of the case body 30. The case body 30 and the case lid 40 are joined together by welding, adhesive bonding, screwing, or the like to seal the opening. The case body 30 and the case lid 40 may be made of the same material or different materials.

[0030] As shown in Fig. 2 , a positive external terminal 28 is disposed on the upper surface of the case lid 40 around a corner in the negative X-axis direction and the positive Y-axis direction. A negative external terminal 29 is disposed on the upper surface of the case lid 40 around a corner in the negative X-axis direction and the negative Y-axis direction. In the present embodiment, a case in which one positive external terminal 28 and one negative external terminal 29 are provided on the case 2 has been illustrated, but a plurality of positive external terminals 28 and a plurality of negative external terminals 29 may be provided on the case 2. The positions of the positive external terminal 28 and the negative external terminal 29 relative to the case main body 30 vary depending on the shape of the energy storage element 10, the joining method, etc., and are therefore not limited to the positional relationship shown in Fig. 2 .

[0031] The energy storage element 10 is a secondary battery (single cell) that can charge and discharge electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium-ion secondary battery. The energy storage element 10 has a shape that is longer in the X-axis direction than in the Y-axis direction, specifically, a rectangular parallelepiped shape (square, rectangular) that is flattened in the Y-axis direction. In this embodiment, four energy storage element groups 90 each consisting of a plurality of energy storage elements 10 are arranged side by side in the Y-axis direction. One energy storage element group 90 has two energy storage elements 10 arranged side by side in the X-axis direction. Each energy storage element 10 may be covered with an insulating film. A detailed description of the configuration of the energy storage element 10 will be given later.

[0032] The spacer 20 is a member that is flat in the Y-axis direction and is arranged alongside the energy storage element group 90 in the Y-axis direction, and that insulates and / or heats the energy storage element group 90 from other members. The spacer 20 is an insulating plate or a heat insulating plate that is arranged adjacent to the energy storage element group 90 in the positive or negative Y-axis direction of the energy storage element group 90, and that insulates and / or heats the energy storage element group 90 from each other or from the energy storage element group 90 to the case 2. The spacer 20 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.

[0033] Among the spacers 20, the spacers 20 arranged between adjacent energy storage element groups 90 are intermediate spacers, and the two spacers 20 arranged at the ends of the plurality of energy storage element groups 90 in the Y-axis direction are end spacers. All of the spacers 20 may be formed of the same material, or some of the spacers 20 may be formed of different materials. The spacers 20 have an outer shape based on a flat rectangular parallelepiped shape. Specifically, the spacers 20 are formed into rectangular shapes that are elongated in the X-axis direction when viewed in the Y-axis direction. In FIG. 2 , the length of the spacer 20 in the X-axis direction is approximately the same as the length of two energy storage elements 10 lined up in the X-axis direction. However, the length of the spacer may be approximately the same as the length of one energy storage element 10 in the X-axis direction or may be shorter than the length of one energy storage element 10 in the X-axis direction. Furthermore, the spacers 20 may be omitted from the viewpoint of improving the energy density of the energy storage device 1.

[0034] The bus bar 25 is connected (joined) to terminals 300 of the plurality of energy storage elements 10. Specifically, the plurality of bus bars 25 connect the terminals 300 of the plurality of energy storage elements 10 to each other, and also electrically connect the terminals 300 of the energy storage elements 10 to the positive electrode external terminal 28 and the negative electrode external terminal 29. The bus bar 25 and the terminals 300 are connected (joined) by welding or the like, but the connection form is not particularly limited. The bus bar 25 is 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.

[0035] The multiple bus bars 25 include parallel bus bars 251 (see FIG. 6 ), series bus bars 252 (see FIG. 7 ), and external terminal bus bars (not shown). The parallel bus bars 251 are conductive members for electrically connecting two adjacent energy storage elements 10 in parallel in the X-axis direction. The series bus bars 252 are conductive members for electrically connecting two adjacent energy storage element groups 90 in series in the Y-axis direction. The external terminal bus bars are conductive members for electrically connecting the multiple energy storage element groups 90 to the positive external terminals 28 and the negative external terminals 29 in series.

[0036] [Description of Energy Storage Element] The energy storage element 10 according to the embodiment will be generally described with reference to Fig. 3 and Fig. 4. Fig. 3 is a perspective view showing the appearance of the energy storage element 10 according to the embodiment. Fig. 4 is an exploded perspective view showing the components of the energy storage element 10 according to the embodiment.

[0037] The energy storage element 10 is an energy storage element that can be charged with electricity from an external source and can discharge electricity to an external source. In this embodiment, the energy storage element 10 has a substantially rectangular parallelepiped shape. The energy storage element 10 is not limited to a nonaqueous electrolyte secondary battery, but 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, an elongated cylinder, an elliptical cylinder, a cylindrical shape, or the like other than a rectangular parallelepiped.

[0038] As shown in Figures 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 disposed on the sides, above, or below the electrode assembly 700, an insulating film enveloping the electrode assembly 700, etc. may also be disposed.

[0039] The container 100 is a case having an external shape (approximately rectangular parallelepiped shape) based on a rectangular parallelepiped shape that is elongated and flattened in the X-axis direction. The length of the container 100 in the X-axis direction and the length in 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 reference rectangular parallelepiped shape is illustrated by a two-dot chain line L1. Specifically, the container 100 has an external shape that is elongated in the X-axis direction and flattened in the Y-axis direction, with four rectangular cutouts formed at the top and bottom of both ends in the X-axis direction. When viewed from the reference rectangular parallelepiped shape, each cutout can be considered to form a recess. Of the multiple cutouts, a pair of cutouts located at the top of the container 100 each form a first recess 101, and a pair of cutouts located at the bottom of the container 100 each form a second recess 102. That is, 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. Here, the end of the container 100 in the positive direction of the X-axis is referred to as the first side surface portion 110, and the end in the negative direction of the X-axis is referred to as the second side surface portion 120. The first side surface portion 110 is a portion in the X-axis direction that is within 20% of the length of the container 100 from the end face of the container 100 in the positive direction of the X-axis. The second side surface portion 120 is a portion in the X-axis direction that is within 20% of the length of the container 100 from the end face of the container 100 in the negative direction of the X-axis.

[0040] 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 located 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.

[0041] 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 have a shape that penetrates 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 have a shape that penetrates in the Y-axis direction.

[0042] 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 located 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.

[0043] 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 of the container 100 in the negative X-axis direction and the positive Z-axis direction), the wall surfaces in the X-axis direction and the Z-axis direction are recessed, and the wall surfaces are penetrating 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 of the container 100 in the negative X-axis direction and the negative Z-axis direction), the wall surfaces in the X-axis direction and the Z-axis direction are recessed, and the wall surfaces are penetrating in the Y-axis direction.

[0044] In this container 100, both end faces facing 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.

[0045] 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.

[0046] The container 100 has a container body 160 and a lid 170, and is formed into a substantially rectangular parallelepiped shape by assembling the container body 160 and the lid 170. The container body 160 has a pair of long sides 130 and a bottom surface 150. The 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.

[0047] 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.

[0048] 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 includes 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 bottom side surface 115, a bent plate portion at its end in the negative direction of the X-axis, which includes 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, and a flat, rectangular top wall portion at its end in the positive direction of the Z-axis, which includes a top surface 140.

[0049] With this configuration, the container 100 is configured such that the electrode assembly 700 and the like are housed inside the container body 160, and then 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, an aluminum alloy, iron, or plated steel sheet.

[0050] Here, the lid 170 is formed with a liquid injection portion (not shown) and a gas exhaust valve 190. The liquid injection portion is a portion for injecting electrolyte into the container 100 during the manufacture of the energy storage element 10. The gas exhaust valve 190 is a safety valve that releases pressure when the pressure inside the container 100 increases excessively. In this embodiment, the gas exhaust valve 190 is provided on the first lower side surface 115.

[0051] The terminals 300 are terminals (positive electrode terminal and negative electrode terminal) electrically connected to the electrode body 700 via the current collector 600. In other words, the terminals 300 are metal members that draw out electricity stored in the electrode body 700 to the external space of the energy storage element 10 and introduce electricity into the internal space of the energy storage element 10 in order to store electricity in the electrode body 700. The 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.

[0052] In the present 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 that protrudes 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 passes 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 passing through the terminal installation surface of the lid, the external gasket 400, the internal gasket 500, and the current collector 600.

[0053] Two current collectors 600 are arranged at each end of the electrode body 700 in the X-axis direction. These current collectors 600 are connected (joined) to the electrode body 700 and the terminal 300, and 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 flat-plate-shaped portions formed by bending a single metal plate. The material of the current collector 600 is not particularly limited, but it is preferably formed from a conductive material such as aluminum, an aluminum alloy, copper, or a copper alloy.

[0054] 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.

[0055] 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. In this embodiment, the length of the electrode body 700 in the X-axis direction is 100 mm or more. The length of the electrode body 700 in the X-axis direction may be less than 100 mm, for example, may be approximately 30 mm. The length of the electrode body 700 in the X-axis direction may be longer than the length 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.

[0056] Specifically, two of the multiple tab portions 720 protrude 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.

[0057] [Explanation of the configuration of the electrode assembly] 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.

[0058] 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.

[0059] For example, LiMPO ４ , LiMSiO ４ , LiMBO ３ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.), polyanion compounds such as lithium titanate, LiMn ２ O ４ and LiMn １．５ Ni ０．５ O ４ Spinel-type lithium manganese oxides such as LiMO ２ (M is one or more transition metal elements selected from Fe, Ni, Mn, Co, etc.) can be used. 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, easily graphitizable carbon, low-temperature fired carbon, amorphous carbon, etc.), and silicon oxides.

[0060] The separators 761 and 762 are microporous sheets made of resin. Any known material can be used as the material for the separators 761 and 762 as long as it does not impair the performance of the energy storage device 10. For example, the separators 761 and 762 can be made of a 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.

[0061] 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.

[0062] 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 no active material layer containing an active material is formed and the metal foil (current collector foil) is exposed. The hatched areas in Figure 5 correspond to the active material layer non-formed portions.

[0063] 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 multiple electrode plates (positive electrode plates 740 and negative electrode plates 750).

[0064] 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 a plurality of electrode plates (positive electrode plates 740 and negative electrode plates 750).

[0065] As described above, the electrode body 700 has a main body portion 710 that constitutes the main body of the electrode body 700, and a plurality of tab portions 720 (positive electrode tab portion 721 and negative electrode tab portion 722) that protrude in pairs from both end faces in the X-axis direction of the main body portion 710. Specifically, on both end faces of the main body portion 710, the positive electrode tab portion 721 is arranged on the upper side (positive direction of the Z-axis), and the negative electrode tab portion 722 is arranged on the lower side (negative direction of the Z-axis).

[0066] 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 positioned to sandwich the flat portion 712 in the Z-axis direction.

[0067] The curved portions 711 are curved in a semicircular arc shape so as to protrude in the Z-axis direction as viewed from the X-axis direction, and are curved portions extending in the X-axis direction. The curved portion 711 in the positive Z-axis direction is disposed opposite the top wall portion of the lid 170, and the curved portion 711 in the negative Z-axis direction is disposed opposite the bottom wall portion of the container body 160. In other words, of the pair of curved portions 711, the curved portion 711 in the positive Z-axis direction is a portion that protrudes in the positive Z-axis direction from the flat portion 712 toward the top wall portion of the lid 170 as viewed from the X-axis direction. Of the pair of curved portions 711, the curved portion 711 in the negative Z-axis direction is a portion that protrudes in the negative Z-axis direction from the flat portion 712 toward the bottom wall portion of the container body 160 as viewed from the X-axis direction.

[0068] The flat portion 712 is a rectangular, flat portion that connects the ends of the pair of curved portions 711 and extends parallel to the XZ plane facing the Y-axis direction, and is disposed opposite the long side wall portions on both sides of the container body 160 in the Y-axis direction. The flat portion 712 is a main portion of the electrode body 700, and in this flat portion 712, multiple wound electrode plates (positive electrode plates 740 and negative electrode plates 750) are stacked in the Y-axis direction. In other words, in the flat portion 712, the Y-axis direction is the stacking direction of the multiple electrode plates. As described above, since the flat portion 712 is a main portion of the electrode body 700, the main stacking direction of the electrode body 700 is defined here as the Y-axis direction.

[0069] The curved shape of the curved portion 711 is not limited to a semicircular arc shape, and may be a part of an ellipse, etc., and may be any curved shape. The outer surface of the flat portion 712 facing the Y-axis direction is not limited to being flat, and the outer surface may be slightly concave or slightly bulged.

[0070] [Explanation of Energy Storage Element Group] Next, the energy storage element group 90 will be described. Fig. 6 is a plan view showing the energy storage element group 90 according to the embodiment. In Fig. 6, for convenience of explanation, the polarity of each terminal 300 is illustrated by a mark ("+" for positive electrode, "-" for negative electrode). Such marks 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.

[0071] As shown in Fig. 6 , two storage elements 10 constituting a storage element group 90 are arranged side by side in the X-axis direction. Here, the storage element 10 in the positive X-axis direction is referred to as the first storage element 11, and the storage element 10 in the negative X-axis direction is referred to as the second storage element 12. In this manner, this embodiment illustrates a case in which the N is added from the first storage element 11 to the Xth storage element from the positive X-axis direction to the negative X-axis direction. The N may also be added from the first storage element 11 to the Xth storage element from the negative X-axis direction to the positive X-axis direction.

[0072] The first storage element 11 includes a first positive electrode terminal 310a, a second positive electrode terminal 310b, a first negative electrode terminal 320a, and a second negative electrode terminal 320b as terminals 300. Specifically, the first positive electrode terminal 310a and the first negative electrode terminal 320a are arranged at a first end (first side surface portion 110) of the first storage element 11 in the positive direction of the X axis. The first positive electrode terminal 310a is arranged in a first recess 101 of the first side surface portion 110, and the first negative electrode terminal 320a is arranged in a second recess 102 of the first side surface portion 110. In other words, the first recess 101 of the first side surface portion 110 is an example of a first positive electrode notch, and the second recess 102 of the first side surface portion 110 is an example of a first negative electrode notch.

[0073] A second positive electrode terminal 310b and a second negative electrode terminal 320b are arranged at a second end (second side surface portion 120) in the negative X-axis direction of first storage element 11. Second positive electrode terminal 310b is arranged in first recess 101 of second side surface portion 120, and second negative electrode terminal 320b is arranged in second recess 102 of second side surface portion 120. In other words, first recess 101 of second side surface portion 120 is an example of a second positive electrode cutout portion, and second recess 102 of second side surface portion 120 is an example of a second negative electrode cutout portion.

[0074] The second storage element 12 includes a third positive terminal 310c, a fourth positive terminal 310d, a third negative terminal 320c, and a fourth negative terminal 320d as terminals 300. Specifically, the third positive terminal 310c and the third negative terminal 320c are arranged at a third end (first side surface portion 110) of the second storage element 12 in the positive direction of the X axis. The third positive terminal 310c is arranged in the first recess 101 of the first side surface portion 110, and the third negative terminal 320c is arranged in the second recess 102 of the first side surface portion 110.

[0075] A fourth positive terminal 310d and a fourth negative terminal 320d are arranged at a fourth end (second side surface portion 120) in the negative X-axis direction of second storage element 12. Fourth positive terminal 310d is arranged in first recess 101 of second side surface portion 120, and fourth negative terminal 320d is arranged in second recess 102 of second side surface portion 120.

[0076] In the energy storage element group 90, the second end of the first energy storage element 11 and the third end of the second energy storage element 12 face each other in the X-axis direction. The second positive electrode terminal 310b and the third positive electrode terminal 310c are electrically connected by a parallel bus bar 251, and the second negative electrode terminal 320b and the third negative electrode terminal 320c are electrically connected by a parallel bus bar 251. Each parallel bus bar 251 is contained within the first recess 101 or the second recess 102 in the Z-axis direction and is configured not to protrude beyond the outer shape of the container 100 in the Z-axis direction. This prevents each parallel bus bar 251 from consuming space outside the container 100. Note that a portion of each parallel bus bar 251 may protrude from the first recess 101 or the second recess 102 in the Z-axis direction. Even in this case, since another portion of each parallel bus bar 251 is housed in the first recess 101 or the second recess 102 in the Z-axis direction, it is possible to reduce the space consumed outside the container 100.

[0077] FIG. 7 is an exploded perspective view of multiple energy storage element groups 90 according to the embodiment. In FIG. 7, the series bus bar 252 is indicated by a dashed line, and the gas release valve 190 is not shown. As shown in FIG. 7, multiple energy storage element groups 90 (four energy storage element groups 90) are arranged along the Y-axis direction and electrically connected in series. Here, the energy storage element groups 90 are referred to as a first energy storage element group 91, a second energy storage element group 92, a third energy storage element group 93, and a fourth energy storage element group 94, in that order from the positive direction of the Y-axis. In this embodiment, a case where the n is incremented from the first energy storage element group 91 to the x-th energy storage element group from the positive direction of the Y-axis to the negative direction of the Y-axis is illustrated. The n may also be incremented from the first energy storage element group 91 to the x-th energy storage element group from the negative direction of the Y-axis to the positive direction of the Y-axis. The first storage element group 91, the second storage element group 92, the third storage element group 93, and the fourth storage element group 94 are storage element groups of the same type. Here, being storage element groups of the same type means that the overall shapes of a certain storage element group and another storage element group to be compared are the same or similar. It is not necessary for all of the components constituting the storage element groups to be similar. It is sufficient that the arrangement of each terminal (positive terminal, negative terminal) in a certain storage element group is the same as the arrangement of each terminal (positive terminal, negative terminal) in another storage element group to be compared. In this case, if the arrangement of each terminal in a certain storage element group is the same as the arrangement of each terminal in another storage element group when one of the storage element groups is rotated up and down or left and right, then the two can be said to be of the same type.

[0078] The positive electrode terminals of the first energy storage element group 91 and the third energy storage element group 93 are disposed in the upper part of the container 100, and the positive electrode terminals of the second energy storage element group 92 and the fourth energy storage element group 94 are disposed in the lower part of the container 100. In other words, the arrangement of the positive electrode terminals and negative electrode terminals of the first energy storage element group 91 and the third energy storage element group 93 is the inverse of the arrangement of the positive electrode terminals and negative electrode terminals of the second energy storage element group 92 and the fourth energy storage element group 94 in the Z-axis direction. In addition, in the present embodiment where each energy storage element group is configured such that X=2, i.e., the first energy storage elements 11 and the second energy storage elements 12, the arrangement of the terminals located at the ends in the X-axis direction is as follows: The arrangement of the first positive electrode terminals 310a and the first negative electrode terminals 320a of the first storage elements 11 constituting the first storage element group 91 is the inversion in the Z-axis direction of the arrangement of the first positive electrode terminals 310a and the first negative electrode terminals 320a of the first storage elements 11 constituting the second storage element group 92. Furthermore, the arrangement of the fourth positive electrode terminals 310d and the first negative electrode terminals 320d of the second storage elements 12 constituting the first storage element group 91 is the inversion in the Z-axis direction of the arrangement of the fourth positive electrode terminals 310d and the fourth negative electrode terminals 320d of the second storage elements 12 constituting the second storage element group 92.

[0079] The first positive electrode terminal 310a of the first energy storage element 11 in the first energy storage element group 91 and the first negative electrode terminal 320a of the first energy storage element 11 in the second energy storage element group 92 are electrically connected directly by a series bus bar 252. The fourth positive electrode terminal 310d of the second energy storage element 12 in the second energy storage element group 92 and the fourth negative electrode terminal 320d of the second energy storage element 12 in the third energy storage element group 93 are electrically connected directly by a series bus bar 252. The first positive electrode terminal 310a of the first energy storage element 11 in the third energy storage element group 93 and the first negative electrode terminal 320a of the first energy storage element 11 in the fourth energy storage element group 94 are electrically connected directly by a series bus bar 252. It is preferable that each series bus bar 252, like each parallel bus bar 251, is contained within the first recess 101 and the second recess 102 and does not protrude from the container 100 in the Z-axis direction.

[0080] The fourth positive electrode terminal 310d of the second energy storage element 12 of the first energy storage element group 91 is electrically connected in series to the positive external terminal 28 via an external terminal bus bar (not shown) or the like. The fourth negative electrode terminal 320d of the second energy storage element 12 of the first energy storage element group 91 is electrically connected in series to the negative external terminal 29 via an external terminal bus bar or the like (see FIG. 2 ). The fourth positive electrode terminal 310d of the second energy storage element 12 of the fourth energy storage element group 94 is electrically connected in series to the positive external terminal 28 via an external terminal bus bar or the like. The fourth negative electrode terminal 320d of the second energy storage element 12 of the fourth energy storage element group 94 is electrically connected in series to the negative external terminal 29 via an external terminal bus bar or the like (see FIG. 2 ). It is preferable that each external terminal bus bar is housed in the first recess 101 and the second recess 102, similar to each parallel bus bar 251, and does not protrude from the container 100 in the Z-axis direction.

[0081] [Explanation of Effects] As described above, according to the embodiment of the present invention, the second positive electrode terminal 310b and the third positive electrode terminal 310c of the first energy storage element 11 and the second energy storage element 12 adjacent to each other in the X-axis direction (first direction) are electrically connected, and the second negative electrode terminal 320b and the third negative electrode terminal 320c are electrically connected. In other words, the first energy storage elements 11 and the second energy storage elements 12 arranged in the X-axis direction can be electrically connected in parallel, and the energy storage element group 90 as a whole can be made long in the X-axis direction. This makes it easier to manufacture the energy storage element group 90 that is long in the X-axis direction, even compared to when each energy storage element 10 is made long in the X-axis direction.

[0082] Therefore, by adjusting the number of installed energy storage elements 10 that make up the energy storage element group 90, the length of the energy storage element group 90 in the X-axis direction can be adjusted, and there is a high degree of freedom in design.

[0083] To explain in more detail, according to this embodiment, when four-terminal structure energy storage elements 10 are connected in parallel in the longitudinal direction, and when an energy storage element group 90 formed by connecting energy storage elements 10 in parallel is connected in series, it is possible to shorten the bus bars (series bus bar 252 and parallel bus bar 251) that join the terminals. This reduces the resistance of the energy storage device 1. Furthermore, it is possible to improve the output and charging performance of the energy storage device 1. In addition, it is possible to reduce the cost of the energy storage device 1.

[0084] Each energy storage element 10 has two positive electrode terminals and two negative electrode terminals, which are electrically connected in parallel, so that electrical resistance after connection can be suppressed.

[0085] Since the plurality of energy storage element groups 90 are electrically connected in series while being arranged along the Y-axis direction (third direction), it is possible to make the energy storage device 1 compact. Specifically, in adjacent energy storage element groups 90, the series-connected terminals are adjacent to each other in the Y-axis direction (third direction), so the length of the conductive members and the space required for handling the conductive members can be small. As a result, it is possible to make the energy storage device 1 including the plurality of energy storage element groups 90 compact.

[0086] The arrangement of the positive and negative terminals of the first energy storage element group 91 is the inverse of the arrangement of the positive and negative terminals of the second energy storage element group 92 in the Z-axis direction (second direction), so the first energy storage element group 91 and the second energy storage element group 92 can be made to have the same type. Therefore, the first energy storage element group 91 and the second energy storage element group 92 can have a common structure. The same applies to the third energy storage element group 93 and the fourth energy storage element group 94.

[0087] In this way, the arrangement of the first positive electrode terminals 310a and the first negative electrode terminals 320a of the first storage elements 11 included in the first storage element group 91 is the inversion in the Z-axis direction of the arrangement of the first positive electrode terminals 310a and the first negative electrode terminals 320a of the first storage elements 11 included in the second storage element group 92. On the other hand, the arrangement of the fourth positive electrode terminals 310d and the fourth negative electrode terminals 320d of the second storage elements included in the first storage element group is the inversion in the Z-axis direction of the arrangement of the fourth positive electrode terminals 310d and the fourth negative electrode terminals 320d of the second storage elements included in the second storage element group. In other words, the arrangement of the terminals (positive electrode terminals and negative electrode terminals) at both ends of a certain storage element group 90 (e.g., the first storage element group 91) is the inversion in the Z-axis direction of the arrangement of the terminals at both ends of an adjacent storage element group 90 (e.g., the second storage element group 92).

[0088] The positive external terminal 28 and the negative external terminal 29 of the case 2 (housing) are electrically connected to the plurality of storage element groups 90, so that even when the plurality of storage element groups 90 are housed in the case 2, electrical connection with external equipment can be easily made via the positive external terminal 28 and the negative external terminal 29.

[0089] The first positive electrode terminal 310a is disposed in the first recess 101 (first positive electrode cutout) of the first side surface portion 110, and the first negative electrode terminal 320a is disposed in the second recess 102 (first negative electrode cutout) of the first side surface portion 110. Similarly, the second positive electrode terminal 310b is disposed in the first recess 101 (second positive electrode cutout) of the second side surface portion 120, and the second negative electrode terminal 320b is disposed in the second recess 102 (second negative electrode cutout) of the second side surface portion 120. This allows at least a portion of the conductive members (parallel bus bar, series bus bar, and external terminal bus bar) connected to each terminal to be disposed within the first recess 101 and the second recess 102. This makes it less likely that the conductive members will protrude outward from the energy storage device 10, thereby reducing space consumption outside the energy storage device 10.

[0090] [Explanation of Modifications] Modifications of the above-described embodiment will be described below. In the following description, the same parts as those in the above-described embodiment or other modifications will be denoted by the same reference numerals, and the description thereof may be omitted.

[0091] (Variation 1) Variation 1 of the above embodiment will be described. In the above embodiment, a case has been described in which two adjacent energy storage element groups 90 in the Y-axis direction are electrically connected in series by only one series bus bar 252. Variation 1 will describe a case in which two adjacent energy storage element groups 90 in the Y-axis direction are electrically connected in series by two series bus bars 252. Fig. 8 is an exploded perspective view showing a plurality of energy storage element groups 90 according to Variation 1. Fig. 8 is a view corresponding to Fig. 7 .

[0092] 8 , the first positive electrode terminal 310a of the first energy storage element 11 of the first energy storage element group 91 and the first negative electrode terminal 320a of the first energy storage element 11 of the second energy storage element group 92 are electrically connected directly by a series bus bar 252. The first negative electrode terminal 320a of the first energy storage element 11 of the first energy storage element group 91 and the first positive electrode terminal 310a of the first energy storage element 11 of the second energy storage element group 92 are electrically connected directly by a series bus bar 252. The fourth positive electrode terminal 310d of the second energy storage element 12 of the second energy storage element group 92 and the fourth negative electrode terminal 320d of the second energy storage element 12 of the third energy storage element group 93 are electrically connected directly by a series bus bar 252. The fourth negative electrode terminal 320d of the second energy storage element 12 of the second energy storage element group 92 and the fourth positive electrode terminal 310d of the second energy storage element 12 of the third energy storage element group 93 are electrically connected directly by a series bus bar 252. The first positive electrode terminal 310a of the first energy storage element 11 of the third energy storage element group 93 and the first negative electrode terminal 320a of the first energy storage element 11 of the fourth energy storage element group 94 are electrically connected directly by a series bus bar 252. The first negative electrode terminal 320a of the first energy storage element 11 of the third energy storage element group 93 and the first positive electrode terminal 310a of the first energy storage element 11 of the fourth energy storage element group 94 are electrically connected directly by a series bus bar 252. In other words, the multiple energy storage element groups 91 (the first energy storage element group 91, the second energy storage element group 92, the third energy storage element group 93, and the fourth energy storage element group 94) are connected in series.

[0093] (Variation 2) Variation 2 of the above embodiment will be described. In the above embodiment, a case where the positive and negative terminals are arranged in the same manner on the first side surface portion 110 and the second side surface portion 120 of the energy storage element 10 is illustrated. Variation 2 illustrates a case where the positive and negative terminals are arranged inverted in the Z-axis direction on the first and second side surface portions of the energy storage element. Fig. 9 is an exploded perspective view showing a group 90f of multiple energy storage elements according to Variation 2. Fig. 9 is a view corresponding to Fig. 7.

[0094] 9 , in the first energy storage element 11 f of the first energy storage element group 91 f, the first positive electrode terminal 310 a is arranged on the upper part of the first side surface portion 110 f, and the first negative electrode terminal 320 a is arranged on the lower part of the first side surface portion 110 f. On the other hand, in the first energy storage element 11 f of the first energy storage element group 91 f, the second negative electrode terminal 320 b is arranged on the upper part of the second side surface portion 120 f, and the second positive electrode terminal 310 b is arranged on the lower part of the second side surface portion 120 f.

[0095] In the second energy storage element 12f of the first energy storage element group 91f, the third negative electrode terminal 320c is disposed on the upper part of the first side surface portion 110f, and the third positive electrode terminal 310c is disposed on the lower part of the first side surface portion 110f. On the other hand, in the second energy storage element 12f of the first energy storage element group 91f, the fourth positive electrode terminal 310d is disposed on the upper part of the second side surface portion 120f, and the fourth negative electrode terminal 320d is disposed on the lower part of the second side surface portion 120f. In other words, the first energy storage element 11f and the second energy storage element 12f are energy storage elements of the same type but inverted in the Y-axis direction. Here, being energy storage elements of the same type means that the overall shape of one energy storage element and another energy storage element to be compared are the same or similar. Not all of the components constituting the energy storage elements need to be similar. It is sufficient that the arrangement of the terminals (positive terminals, negative terminals) in a certain storage element is the same as the arrangement of the terminals (positive terminals, negative terminals) in another storage element to be compared, and that the terminals in the certain storage element are of approximately the same size. In this case, if the arrangement of the terminals in the certain storage element is the same as the arrangement of the terminals in the other storage element when one of the certain storage element and the other storage element is rotated up and down or left and right, then the two can be said to be of the same type.

[0096] The same applies to the third power storage element group 93f. The second power storage element group 92f has the same shape as the first power storage element group 91f, but is arranged in an inverted position in the Z-axis direction. The same applies to the fourth power storage element group 94f.

[0097] (Modification 3) Modification 3 of the above embodiment will be described. In the above embodiment, the case where the energy storage element group 90 is composed of only two energy storage elements 10 has been exemplified. In this modification 3, the case where X is 3, that is, an energy storage element group 90g composed of three energy storage elements, will be described. Fig. 10 is a perspective view showing a plurality of energy storage element groups 90g according to modification 3 in an expanded state. Fig. 10 is a view corresponding to Fig. 7.

[0098] 10 , each energy storage element group 90g has three energy storage elements 10 arranged in the X-axis direction. Two energy storage elements 10 adjacent to each other in the X-axis direction are electrically connected in parallel by a parallel bus bar 251. Two energy storage element groups 90g adjacent to each other in the Y-axis direction are electrically connected in series by a series bus bar 252.

[0099] In this way, even when three or more storage elements 10 are arranged in parallel in the X-axis direction in each of three or more storage element groups 90g electrically connected in series, the energy storage device can be made compact. For example, although it is not impossible to connect three or more conventional two-terminal storage elements in parallel, it has been difficult to simplify the connection structure. In the energy storage element group 90g of this modification, each storage element 10 has four terminals (two positive terminals and two negative terminals), which allows for a simple connection structure when connecting three or more storage elements in parallel. In other words, although it is not impossible to connect three or more two-terminal storage elements in parallel, the bus bar structure connecting the terminals is complex and long, which increases the resistance of the energy storage device. According to this modification, it is possible to shorten the bus bar connecting the terminals, thereby reducing the resistance of the energy storage device. Furthermore, it is possible to improve the output and charging performance of the energy storage device. In addition, it is possible to reduce the cost of the energy storage device.

[0100] In addition, a group of storage elements may be formed by arranging three storage elements (such as the first storage element 11f in variant example 2) in the X-axis direction, with the positive and negative terminals arranged inverted in the Z-axis direction between the first side portion and the second side portion.

[0101] (Variation 4) In the above embodiment, an energy storage device 10 including a container 100 with flat top and bottom surfaces 140 and 150 has been exemplified. In this variation 4, an energy storage device including a container with curved top and bottom surfaces will be described. Fig. 11 is an exploded perspective view showing the components of an energy storage device 10H according to variation 4. Fig. 11 is a view corresponding to Fig. 4.

[0102] As shown in FIG. 11 , the container 100h 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 100h, 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, with both ends in the X-axis direction corresponding to the first side face 110 and the second side face 120. Of the both end faces opposing each other in the Z-axis direction, the end face facing the positive Z-axis direction is the top face 140h, and the end face facing the negative Z-axis direction is the bottom face 150h. The top face 140h is a curved surface elongated in the X-axis direction and protruding in the positive Z-axis direction. The bottom face 150 is a curved surface elongated in the X-axis direction and protruding in the negative Z-axis direction.

[0103] The container 100h has a container body 160h and a pair of lids 170h, and the container body 160h and the lids 170h are assembled together to form an elongated cylindrical shape. The container body 160h is formed in an elongated cylindrical shape that penetrates in the X-axis direction.

[0104] The pair of lids 170h are members that seal both ends of the container body 160 in the X-axis direction. One lid 170h seals the end of the container body 160h in the positive direction of the X-axis. One lid 170h is formed from a metal plate and is bent to correspond to the shape of the end of the container body 160h in the negative direction of the X-axis. One lid 170h 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 170h seals the end of the container body 160h in the negative direction of the X-axis. The other lid 170h is formed from a metal plate and is bent to correspond to the shape of the end of the container body 160h in the positive direction of the X-axis. The other cover 170 h 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 .

[0105] With this configuration, the container 100h has a structure in which, after the electrode body 700 and the like are housed inside the container body 160h, the container body 160h and the lid body 170h are joined by welding or the like, thereby sealing the interior.

[0106] (Variation 5) In the above embodiment, an example was given in which all of the energy storage elements 10 in each energy storage element group 90 have four terminals 300. However, in some of the energy storage elements 10 according to the embodiment, 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 10. In this variation 5, a description is given of an energy storage element group including energy storage elements from which terminals that are not connected to the connection target have been removed (decided not to be provided). FIG. 12 is a plan view showing an energy storage element group 90j according to variation 5. FIG. 12 is a view corresponding to FIG. 6.

[0107] 12 , the first energy storage element 11 has four terminals 300, while the second energy storage element 12j has three terminals 300. Specifically, the second energy storage element 12j does not have a terminal provided in the second recess 102j in the negative X-axis direction. In this case, it is not necessary to form a through hole for installing a terminal in the second recess 102j in advance, or the through hole may be sealed by laser welding or the like after formation.

[0108] (Variation 6) Variation 6 describes a variation of the busbar. FIG. 13A is a top view showing an energy storage element group busbar 251k according to Variation 6. The energy storage element group busbar 251k includes a fuse portion 253k in which the cross-sectional area (cross-sectional area parallel to the YZ plane) of a middle portion in the direction in which the energy storage elements 10K are connected (middle portion in the X-axis direction) is smaller than the cross-sectional area (cross-sectional area parallel to the YZ plane) of other portions in the X-axis direction. Here, the middle portion can also be referred to as the middle portion of the energy storage element group busbar 251k in the direction in which current flows. The cross-sectional area of ​​the energy storage element group busbar 251k is the area of ​​a cross section perpendicular to the direction in which current flows. The fuse portion 253k is the portion of the energy storage element group busbar 251k with the smallest cross-sectional area at a position sandwiched in the X-axis direction between two terminals 300k connected by the energy storage element group busbar 251k. The fuse portion 253k is designed to be physically cut off when a large current flows. For example, if a malfunction causes a short circuit in a certain energy storage element 10K, a large current may flow to other energy storage elements via the energy storage element group bus bar 251k. In such a case, a large current flows through the fuse portion 253k of the energy storage element group bus bar 251k, causing the fuse portion 253k to cut off, thereby preventing a large current from flowing from the shorted energy storage element 10K to the other energy storage elements.

[0109] Furthermore, in at least one of the two energy storage elements 10K connected by the energy storage element group bus bar 251k, a gas exhaust valve 190k may be provided in the recess (first recess 101 or second recess 102) in which the energy storage element group bus bar 251k is disposed. This makes it possible to cut the fuse portion 253k of the energy storage element group bus bar 251k by high-temperature gas exhausted from the gas exhaust valve 190k.

[0110] FIG. 13B is a perspective view showing an inter-storage element group bus bar 252k according to Modification 6. The inter-storage element group bus bar 252k includes a fuse portion 254k in which the cross-sectional area (cross-sectional area parallel to the XZ plane) of a middle portion in the direction connecting adjacent energy storage element groups (middle portion in the Y-axis direction) is smaller than the cross-sectional area (cross-sectional area parallel to the XZ plane) of other portions in the Y-axis direction. Here, the middle portion can also be said to be the middle portion of the inter-storage element group bus bar 252k in the direction of current flow. The cross-sectional area of ​​the inter-storage element group bus bar 252k is the area of ​​a cross section perpendicular to the direction of current flow. The fuse portion 253k is the portion of the inter-storage element group bus bar 252k that has the smallest cross-sectional area at a position sandwiched in the Y-axis direction between two terminals 300k connected by the inter-storage element group bus bar 252k. In the inter-storage element group bus bar 252k, when a large current flows through the fuse portion 254k, the fuse portion 254k is cut, thereby preventing a large current from flowing from the short-circuited storage element group to other storage element groups.

[0111] In at least one of the two energy storage elements 10K connected by the energy storage element group bus bar 252k, a gas exhaust valve 190k may be provided in the recess (first recess 101 or second recess 102) in which the energy storage element group bus bar 252k is disposed. This makes it possible to cut the fuse portion 253k of the series bus bar 252k by high-temperature gas exhausted from the gas exhaust valve 190k.

[0112] The fuse portion may be provided on some of the bus bars. For example, a fuse portion may be provided on only one of the plurality of intra-energy-storage-element-group bus bars included in one energy storage element group. A fuse portion may be provided on only one of the plurality of inter-energy-storage-element-group bus bars connecting the plurality of energy storage element groups.

[0113] (Other Modifications) While the power storage device according to the embodiment of the present invention has been described above, 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.

[0114] 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.

[0115] 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 in an accordion-like manner. Specific examples of the latter include a form in which a separator is folded in an accordion-like manner to sandwich a rectangular electrode plate, or a form in which an electrode plate and a separator are stacked and then folded in an accordion-like manner. A bipolar electrode assembly is also possible.

[0116] In the above embodiment, the energy storage device 1 is illustrated as including a plurality of energy storage element groups 90. However, the energy storage device may include at least one energy storage element group, and the number of installed energy storage element groups may be any number.

[0117] In the above embodiment, the terminal installation 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 terminal installation surface may be the first upper side surface, the first lower side surface, the second upper side surface, or the second lower side 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.

[0118] In the above embodiment, the energy storage element 10 is illustrated as having four cutouts (the first recess 101 and the second recess 102). However, the number of cutouts may be any number, and the energy storage element 10 may not have any cutouts.

[0119] The terminals provided on each of the energy storage elements may be bolt terminals. At least a portion of the cutout portion (the first recess and the second recess) may be cut out in a curved shape.

[0120] Any combination of the components included in the above-described embodiments and their modifications is also included within the scope of the present invention.

[0121] The present invention can be applied to an electricity storage device including an electricity storage element such as a lithium ion secondary battery.

[0122] REFERENCE SIGNS LIST 1 Energy storage device 2 Case (housing) 10, 10H, 10K Energy storage element 11, 11f First energy storage element 12, 12f Second energy storage element 20 Spacer 25 Bus bar 28 Positive electrode external terminal 29 Negative electrode external terminal 90, 90f, 90g Energy storage element group 91, 91f First energy storage element group 92, 92f Second energy storage element group 93, 93f Third energy storage element group 94, 94f Fourth energy storage element group 100, 100h Container 101 First recess 102 Second recess 130 Long side surface 140, 140h Top surface 150, 150h Bottom surface 160, 160h Container body 170, 170h Lid 251, 251k Parallel bus bar 252, 252k Serial bus bars 300 Terminal 310a First positive electrode terminal 310b Second positive electrode terminal 310c Third positive electrode terminal 310d Fourth positive electrode terminal 320a First negative electrode terminal 320b Second negative electrode terminal 320c Third negative electrode terminal 320d Fourth negative electrode terminal 600 Current collector 700 Electrode body

Claims

1. A storage element group includes X storage elements arranged in a first direction and electrically connected in parallel, wherein an Nth storage element, which is an Nth storage element (N is a natural number and 1≦N≦X-1) arranged counting from a first storage element which is an end storage element in the first direction, among the X storage elements, has, as end portions in the first direction, a (2N-1)th end portion at which a (2N-1)th positive electrode terminal and a (2N-1)th negative electrode terminal are arranged, and a (2N)th end portion at which a (2N)th positive electrode terminal and a (2N)th negative electrode terminal are arranged, and an (N+1)th storage element adjacent to the Nth storage element has, as end portions in the first direction, a (2N+1)th end portion at which a (2N+1)th positive electrode terminal and a (2N+1)th negative electrode terminal are arranged, a (2N+2)th end portion having a (2N+2)th positive electrode terminal and a (2N+2)th negative electrode terminal disposed thereon, the (2N) end portion and the (2N+1) end portion facing each other in the first direction, the (2N) positive electrode terminal and the (2N+1) positive electrode terminal being electrically connected to each other, and the (2N) negative electrode terminal and the (2N+1) negative electrode terminal being electrically connected to each other.

2. The energy storage device according to claim 1, comprising x storage element groups, the x storage element groups being arranged along a third direction perpendicular to both the first direction and a second direction in which the (2N) positive electrode terminals and the (2N) negative electrode terminals are arranged, and an nth storage element group which is the nth (n is a natural number and 1≦n≦x-1) storage element group counting from a first storage element group which is an end storage element group in the third direction, among the x storage element groups, is electrically connected in series with an (n+1)th storage element group adjacent to the nth storage element group.

3. The energy storage device according to claim 2, wherein an arrangement of a first positive electrode terminal and a first negative electrode terminal of a first energy storage element included in the nth energy storage element group is an arrangement obtained by inverting, in the second direction, an arrangement of a first positive electrode terminal and a first negative electrode terminal of a first energy storage element included in the (n+1)th energy storage element group; and an arrangement of a (2X)th positive electrode terminal and a (2X)th negative electrode terminal of an Xth energy storage element included in the nth energy storage element group is an arrangement obtained by inverting, in the second direction, an arrangement of a (2X)th positive electrode terminal and a (2X)th negative electrode terminal of an Xth energy storage element included in the (n+1)th energy storage element group.

4. The energy storage device according to claim 2 or 3, comprising a positive external terminal, a negative external terminal, and a housing that houses x groups of energy storage elements, wherein the positive external terminal and the negative external terminal are electrically connected to the x groups of energy storage elements that are connected in series.

5. The energy storage device according to any one of claims 1 to 3, wherein the (2N-1) end comprises: a (2N-1) positive electrode cutout portion in which the (2N-1) positive electrode terminal is arranged; and a (2N-1) negative electrode cutout portion in which the (2N-1) negative electrode terminal is arranged; and the (2N) end comprises: a (2N) positive electrode cutout portion in which the (2N) positive electrode terminal is arranged; and a (2N) negative electrode cutout portion in which the (2N) negative electrode terminal is arranged.

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