Power storage device

Abstract

To provide a power storage device which can inhibit damage of power storage elements.SOLUTION: A power storage device 10 includes power storage elements 200 arranged in a first direction. A first power storage element 200a, located at an end part on one side in the first direction, of the power storage elements 200 has a first container 210a in which a container body 220 and a container lid body 230 are joined to form a joint part 240. The joint part 240 of the first container 210a has: a first joint part 241a which is disposed extending in a second direction intersecting with the first direction at the one side in the first direction; and a second joint part 242a, 243a, or 244a disposed at the side in a direction different from the one side in the first direction. The first joint part 241a has joint strength higher than that of the second joint part 242a, 243a, or 244a.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an energy storage device including a plurality of energy storage elements. [Background technology]

[0002] Conventionally, there has been widely known an energy storage device including a plurality of energy storage elements, in which a container body and a lid body are joined to the container of the energy storage elements to form a joint. For example, Patent Document 1 discloses an energy storage module (energy storage device) in which a plurality of secondary batteries (energy storage elements) are arranged, each having a case (container) in which a case body (container body) and a lid body are welded to form a welded part. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 081917 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional energy storage device, the energy storage element may be damaged. That is, in a configuration in which a container body and a lid are joined to a container of an energy storage element to form a joint, as in the conventional energy storage device, the container of the energy storage element may expand, causing the joint of the container to be damaged. For this reason, it is possible to increase the joint strength of the container joint, but if the joint strength of the container joint is increased too much, problems may occur. For example, if the penetration depth of the weld is made too deep at the joint, problems such as spattering may occur or holes may be formed in the container may occur. For these reasons, the inventor of the present application has found that, in order to suppress damage to the energy storage element, it is possible to increase the joint strength over the entire joint of the container, but in this case, there is a risk that the joint strength may be increased too much at any position of the joint of the container, increasing the risk of problems occurring.

[0005] The present invention was made by the inventors of the present application by focusing on the above-mentioned problem, and has an object to provide an electricity storage device capable of suppressing damage to electricity storage elements. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, an energy storage device according to one embodiment of the present invention is an energy storage device having a plurality of energy storage elements arranged in a first direction, wherein a first energy storage element among the plurality of energy storage elements, which is located at an end on one side of the first direction, has a first container in which a container body and a lid body are joined to form a joint, and the joint of the first container has a first joint portion arranged on one side of the first direction and extending in a second direction intersecting the first direction, and a second joint portion arranged in a direction different from the one side of the first direction, and the first joint portion has a joint strength higher than that of the second joint portion.

[0007] According to this, in the energy storage device, among the joints of the first container of the first energy storage element located at one end in the first direction among the plurality of energy storage elements, the first joint extending in the second direction on one side in the first direction has a higher joint strength than the second joint on the other side in the first direction. Here, in the energy storage device, in a configuration in which the plurality of energy storage elements are arranged in the first direction, among the joints of the first container of the first energy storage element at the end on one side in the first direction, the joint on one side in the first direction is easily damaged. For this reason, among the joints of the first container of the first energy storage element, the first joint extending in the second direction on one side in the first direction is made to have a higher joint strength than the second joint on the other side in the direction other than the one side. In other words, the joint strength of the first joint, which is relatively easily damaged, is made higher than the joint strength of the second joint, which is relatively less likely to be damaged. This reduces the risk of defects compared to increasing the joint strength of both the first joint and the second joint, and can increase the joint strength of the necessary parts, thereby suppressing damage to the energy storage element.

[0008] The first joint portion may be arranged to extend over a length equal to or greater than half the width of the first container in the second direction.

[0009] According to this, the first joint portion of the first container of the first storage element extends over a length equal to or greater than half the width of the first container in the second direction, thereby making it possible to increase the joint strength of the joint portion on one side of the first container in the first direction, thereby making it possible to further suppress damage to the storage element.

[0010] The first joint portion may be arranged to extend to include a central portion in the second direction of a joint portion located on one side of the first container in the first direction.

[0011] In the first energy storage element, when the first container swells, the central portion in the second direction of the joint located on one side of the first container in the first direction swells and is easily damaged. For this reason, the first joint having high joint strength is disposed so as to extend to include the central portion. This makes it possible to increase the joint strength of the easily damaged portion of the joint, thereby further suppressing damage to the energy storage element.

[0012] Of the multiple energy storage elements, a second energy storage element located at the end on the other side of the first direction has a second container in which a container body and a lid are joined to form a joint, and the joint of the second container has a third joint arranged on the other side of the first direction by extending in the second direction, and a fourth joint arranged in a direction different from the other side of the first direction, and the third joint may have a joint strength greater than that of the fourth joint.

[0013] According to this, in the energy storage device, among the joints of the second container of the second energy storage element located at the end on the other side in the first direction among the multiple energy storage elements, the third joint extending in the second direction on the other side in the first direction has a higher joint strength than the fourth joint on the side in the direction different from the other side in the first direction. Here, in the energy storage device, among the joints of the second container of the second energy storage element located at the end on the other side in the first direction of the multiple energy storage elements, the joint on the other side in the first direction is also easily damaged. For this reason, among the joints of the second container of the second energy storage element, the third joint extending in the second direction on the other side in the first direction is made to have a higher joint strength than the fourth joint on the side in the direction different from the other side. In other words, the joint strength of the third joint, which is relatively easily damaged, is made higher than the joint strength of the fourth joint, which is relatively less likely to be damaged. This reduces the risk of malfunction compared to increasing the joint strength of both the third joint and the fourth joint, and can increase the joint strength of the necessary parts, thereby suppressing damage to the energy storage element.

[0014] Each of the first storage element and the second storage element may have a positive terminal and a negative terminal, and the first storage element and the second storage element may be arranged in opposite directions from the positive terminal to the negative terminal.

[0015] In the first storage element, the bonding strength of the first joint is high on one side in the first direction, and in the second storage element, the bonding strength of the third joint is high on the other side in the first direction. In other words, the first storage element and the second storage element have an inverse relationship in terms of bonding strength in the first direction. Therefore, by arranging the positive electrode terminal and the negative electrode terminal of the first storage element and the second storage element in reverse (the direction from the positive electrode terminal to the negative electrode terminal is reversed), the first storage element and the second storage element have a relationship rotated by 180 degrees. This makes it possible to utilize storage elements of the same configuration as the first storage element and the second storage element, and therefore makes it possible to easily realize a configuration that suppresses damage to the storage elements.

[0016] The first container may have a first long side surface on one side in the first direction and a second long side surface on the other side in the first direction, the first joint being arranged on the first long side surface side of the first container, and the second joint being arranged on the second long side surface side of the first container.

[0017] In the first energy storage element, when the first container has a first long side surface on one side in the first direction and a second long side surface on the other side in the first direction, the joint on the first long side surface side is easily damaged. In contrast, the second long side surface presses against the long side surface of the container of the adjacent energy storage element, so the joint on the second long side surface side is less likely to be damaged. Therefore, by arranging the first joint portion on the first long side surface side of the first container and the second joint portion on the second long side surface side of the first container, the joint strength of the first joint portion, which is relatively easily damaged, is made higher than the joint strength of the second joint portion, which is relatively less likely to be damaged. This makes it possible to effectively prevent damage to the energy storage element.

[0018] The first joint portion may have a greater penetration depth by welding than the second joint portion.

[0019] According to this, by making the first joint portion of the first container of the first energy storage element have a deeper penetration depth by welding than the second joint portion, the joint strength of the first joint portion can be easily made higher than the joint strength of the second joint portion, which makes it possible to easily prevent damage to the energy storage element.

[0020] The present invention can be realized not only as such an electricity storage device, but also as a plurality of electricity storage elements. Effect of the Invention

[0021] According to the electricity storage device of the present invention, damage to the electricity storage elements can be suppressed. [Brief description of the drawings]

[0022] [Figure 1] 1 is a perspective view showing an external appearance of a power storage device according to an embodiment; [Diagram 2] FIG. 2 is an exploded perspective view illustrating each component of the electricity storage device according to the embodiment. [Diagram 3] FIG. 2 is a perspective view showing a configuration of an energy storage element according to an embodiment. [Figure 4] 1 is a plan view showing a configuration in which a plurality of energy storage elements are housed in an exterior body of an exterior body according to an embodiment. FIG. [Diagram 5] 13 is a plan view showing a configuration in which a plurality of energy storage elements according to a first modification of the embodiment are housed in an exterior body of the exterior body. FIG. [Figure 6] 13 is a plan view showing a configuration in which a plurality of energy storage elements according to a second modification of the embodiment are housed in an exterior body of the exterior body. FIG. [Figure 7] FIG. 11 is a perspective view showing a configuration of an energy storage element according to a third modified example of the embodiment. [Figure 8] 13 is a plan view showing a configuration in which a plurality of energy storage elements according to a fourth variation of the embodiment are housed in an exterior body of the exterior body. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, a description will be given of an energy storage device according to an embodiment (including its modified examples) of the present invention with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, the arrangement and connection of the components, manufacturing processes, and the order of the manufacturing processes shown in the following embodiments are merely examples and are not intended to limit the present invention. In each drawing, the dimensions are not strictly shown. In each drawing, the same or similar components are given the same reference numerals.

[0024] In the following description and drawings, the arrangement direction of the energy storage elements or the opposing direction of the long side surfaces of the containers of the energy storage elements is defined as the X-axis direction. The arrangement direction of the positive electrode terminal and the negative electrode terminal of one energy storage element or the opposing direction of the short side surfaces of the containers of the energy storage elements is defined as the Y-axis direction. The arrangement direction of the exterior body and the exterior body lid of the energy storage device, the arrangement direction of the container body and the container lid of the energy storage element, or the up-down direction is defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect with each other (orthogonal in this embodiment). Note that, depending on the mode of use, there may be cases where the Z-axis direction is not the up-down direction, but for convenience of explanation, the following description will be given assuming that the Z-axis direction is the up-down direction.

[0025] 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 opposite direction to the positive X-axis direction. The same applies to the Y-axis and Z-axis directions. In the following, the X-axis direction may also be called the first direction, and the Y-axis direction may also be called the second direction. Furthermore, expressions indicating relative directions or attitudes, such as parallel and perpendicular, may also include cases where the directions or attitudes are not strictly the same. For example, two directions being perpendicular to each other not only means that the two directions are completely perpendicular to each other, but also means that the two directions are substantially perpendicular to each other, that is, includes a difference of, for example, about several percent.

[0026] (Embodiment) [1 General Description of Power Storage Device 10] First, a general description will be given of a power storage device 10 according to the present embodiment. Fig. 1 is a perspective view showing the external appearance of the power storage device 10 according to the present embodiment. Fig. 2 is an exploded perspective view showing each component when the power storage device 10 according to the present embodiment is disassembled.

[0027] The power storage device 10 is a device that can charge electricity from an external source and discharge electricity to the outside, and in this embodiment, has a substantially rectangular parallelepiped shape. For example, the power storage device 10 is a battery module (battery pack) used for power storage or power source. Specifically, the power storage device 10 is used as a battery for driving or starting an engine of a moving body such as an automobile, a motorcycle, a watercraft, a ship, a snowmobile, an agricultural machine, a construction machine, or a railway vehicle for an electric railway. Examples of the automobile include an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a gasoline vehicle. Examples of the railway vehicle for the electric railway 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 10 can also be used as a stationary battery for home use or for a power generator.

[0028] 1 and 2, the energy storage device 10 includes an exterior body 100, and a plurality of energy storage elements 200, a bus bar frame 300, a bus bar 400, etc. are housed inside the exterior body 100. In addition to the above components, the energy storage device 10 may also include spacers disposed between the plurality of energy storage elements 200, restraining members (side plates, end plates, etc.) that restrain the plurality of energy storage elements 200, a circuit board for monitoring the charged and discharged states of the energy storage elements 200, etc.

[0029] [1.1 Description of exterior body 100] The exterior body 100 is a box-shaped (approximately rectangular parallelepiped) container (module case) that constitutes the exterior body of the energy storage device 10. In other words, the exterior body 100 is disposed outside the multiple energy storage elements 200, the bus bar frame 300, the bus bar 400, etc., and fixes the energy storage elements 200, etc. at predetermined positions to protect them from impacts and the like. The exterior body 100 is formed of an insulating member such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyether ether ketone (PEEK), tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyether sulfone (PES), ABS resin, or a composite material thereof. The exterior body 100 thereby prevents the energy storage element 200 and the like from coming into contact with external metal members, etc. Note that the exterior body 100 may be formed of a conductive member such as a metal as long as the electrical insulation of the energy storage element 200 and the like is maintained.

[0030] The exterior body 100 has an exterior body main body 110 that constitutes the main body of the exterior body 100, and an exterior body lid body 120 that constitutes the lid body of the exterior body 100. The exterior body main body 110 is a bottomed rectangular cylindrical housing (chassis) with an opening facing the positive Z-axis direction, and contains the energy storage element 200 and the like. The exterior body main body 110 has a pair of opposing short side walls 111 and 112 on both side surfaces in the X-axis direction, a pair of opposing long side walls 113 and 114 on both side surfaces in the Y-axis direction, and a bottom wall 115 on the negative Z-axis direction side.

[0031] The short side walls 111 and 112 are rectangular, flat wall portions that form the short side surfaces of the exterior body 100, and are arranged opposite to the long side surfaces of a container 210 (described later) of the energy storage element 200 in the X-axis direction. The short side walls 111 and 112 are adjacent to the long side walls 113 and 114 and the bottom wall portion 115, and have an outer surface area smaller than that of the long side walls 113 and 114. In this embodiment, the side wall of the exterior body main body 110 in the positive direction of the X-axis is the short side wall portion 111, and the side wall in the negative direction of the X-axis is the short side wall portion 112.

[0032] The long side walls 113 and 114 are rectangular, flat wall portions that form the long side surfaces of the exterior body 100, and are arranged opposite the short side surfaces of the container 210 of the energy storage element 200 in the Y-axis direction. The long side walls 113 and 114 are adjacent to the short side walls 111 and 112 and the bottom wall portion 115, and have a larger outer surface area than the short side walls 111 and 112. In this embodiment, the side wall of the exterior body main body 110 in the positive direction of the Y-axis is the long side wall portion 113, and the side wall in the negative direction of the Y-axis is the long side wall portion 114.

[0033] Bottom wall portion 115 is a rectangular, flat wall portion that forms the bottom surface of exterior body 100, and is disposed opposite to the bottom surface of container 210 of energy storage element 200 in the Z-axis direction. Bottom wall portion 115 is a wall portion adjacent to short side wall portions 111 and 112 and long side wall portions 113 and 114.

[0034] The exterior body lid 120 is a flat rectangular member that is joined to the exterior body 110 by heat sealing or the like and closes the opening of the exterior body 110. The exterior body lid 120 is provided with a positive electrode external terminal 121 and a negative electrode external terminal 122. The electricity storage device 10 charges with electricity from the outside and discharges electricity to the outside via the positive electrode external terminal 121 and the negative electrode external terminal 122. The exterior body 110 and the exterior body lid 120 may be formed of members made of the same material or different materials.

[0035] [1.2 Explanation of other components] The energy storage element 200 is a secondary battery (single cell) capable of charging and discharging electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. The energy storage element 200 has a flattened rectangular parallelepiped shape (rectangular shape), and in this embodiment, eight energy storage elements 200 are arranged in the X-axis direction. The energy storage element 200 has a container 210, a positive electrode terminal 250, and a negative electrode terminal 260. The shape of the energy storage element 200 is not limited to a rectangular parallelepiped shape, and may be a cylindrical shape, an elongated cylindrical shape, or a polygonal prism shape other than a rectangular parallelepiped. The number of the arranged energy storage elements 200 is not particularly limited as long as it is two or more. The energy storage element 200 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than a non-aqueous electrolyte secondary battery, or may be a capacitor. The energy storage element 200 may not be a secondary battery, but may be a primary battery that can use stored electricity without the user having to charge it. The energy storage element 200 may be a pouch-type energy storage element. The configuration of the energy storage element 200 will be described in detail later.

[0036] The bus bar frame 300 is a rectangular, flat member that insulates the bus bar 400 etc. from other members and regulates the position of the bus bar 400 etc. Specifically, the bus bar 400 etc. are placed on the bus bar frame 300 and positioned, and the bus bar frame 300 is placed on the plurality of energy storage elements 200 and positioned relative to the plurality of energy storage elements 200. In this way, the bus bar 400 is positioned relative to the plurality of energy storage elements 200. The bus bar frame 300 may be made of any material as long as it is an electrically insulating member, and is made of, for example, any electrically insulating resin material that can be used for the exterior body 100 described above.

[0037] The bus bar 400 is a rectangular, flat member disposed above the multiple energy storage elements 200 and connected to the electrode terminals (positive electrode terminal 250 and negative electrode terminal 260) of the multiple energy storage elements 200. As a result, the bus bar 400 connects the electrode terminals of the multiple energy storage elements 200 to each other, and also connects the electrode terminals of the end energy storage elements 200 to the positive electrode external terminal 121 and the negative electrode external terminal 122. The bus bar 400 is formed of a conductive member made of metal such as aluminum, an aluminum alloy, copper, or a copper alloy.

[0038] Specifically, the bus bar 400 has bus bars 410, 420, and 430. The bus bar 430 connects two energy storage elements 200 in parallel to form four sets of energy storage element groups, and connects the four sets of energy storage element groups in series. The bus bar 410 is connected to the positive terminals 250 of two energy storage elements 200 in the energy storage element group arranged on the positive external terminal 121 side (X-axis positive direction side), and is connected to the positive external terminal 121 via another bus bar (not shown). The bus bar 420 is connected to the negative terminals 260 of two energy storage elements 200 in the energy storage element group arranged on the negative external terminal 122 side (X-axis negative direction side), and is connected to the negative external terminal 122 via another bus bar (not shown).

[0039] [2. Description of the Energy Storage Element 200] Next, the configuration of the energy storage element 200 will be described in detail. Fig. 3 is a perspective view showing the configuration of the energy storage element 200 according to this embodiment. Specifically, Fig. 3 shows an enlarged external view of an energy storage element 200 located, for example, at the end in the positive direction of the X-axis, among the plurality of energy storage elements 200 shown in Fig. 2. Note that since all of the plurality of energy storage elements 200 have the same configuration, the configuration of one energy storage element 200 will be described in detail below.

[0040] As shown in Fig. 3, the energy storage element 200 has an upper gasket 270 in addition to the above-mentioned container 210, positive electrode terminal 250, and negative electrode terminal 260. A lower gasket, an electrode body, a positive electrode current collector, a negative electrode current collector, an electrolytic solution (non-aqueous electrolyte), and the like are contained inside the container 210, but are not shown. There is no particular limit to the type of the electrolytic solution as long as it does not impair the performance of the energy storage element 200, and various types can be selected. In addition to the above-mentioned components, the energy storage element 200 may have a spacer disposed on the side or below the electrode body, an insulating film that wraps the electrode body, and the like.

[0041] 2.1 Description of the container 210 The container 210 is a rectangular parallelepiped (rectangular or box-shaped) case having a container body 220 with an opening formed therein, and a container lid 230 that closes the opening of the container body 220. The material of the container 210 (container body 220 and container lid 230) is not particularly limited, and can be, for example, a weldable (joinable) metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet, but resin can also be used.

[0042] The container body 220 is a rectangular cylindrical member with a bottom that constitutes the main body of the container 210, and has an opening formed on the positive Z-axis direction side. That is, the container body 220 has a pair of opposing long side portions 221 and 222 on both side surfaces in the Y-axis direction, a pair of opposing short side portions 223 and 224 on both side surfaces in the X-axis direction, and a bottom portion 225 on the negative Z-axis direction side.

[0043] The long side surface portions 221 and 222 are rectangular, flat portions forming the long side surface of the container 210, and are arranged opposite to the long side surface portion 221 or 222 of the container 210 of the adjacent energy storage element 200, or the short side wall portion 111 or 112 of the exterior body 100 in the X-axis direction. The long side surface portions 221 and 222 are adjacent to the short side surface portions 223 and 224 and the bottom surface portion 225, and have a larger area than the short side surface portions 223 and 224. In FIG. 3 , the side surface of the container body 220 in the positive direction of the X-axis is the long side surface portion 221, and the side surface in the negative direction of the X-axis is the long side surface portion 222.

[0044] The short side surface portions 223 and 224 are rectangular, flat portions that form the short side surfaces of the container 210, and are disposed opposite the long side wall portions 113 and 114 of the exterior body 100 in the Y-axis direction. The short side surface portions 223 and 224 are adjacent to the long side surface portions 221 and 222 and the bottom surface portion 225, and have a smaller area than the long side surface portions 221 and 222. In FIG. 3 , the side surface of the container body 220 in the positive direction of the Y-axis is the short side surface portion 223, and the side surface in the negative direction of the Y-axis is the short side surface portion 224.

[0045] Bottom surface portion 225 is a rectangular, flat portion that forms the bottom surface of container 210. Bottom surface portion 225 faces bottom wall portion 115 of exterior body 100 in the Z-axis direction, and is disposed adjacent to long side surface portions 221 and 222 and short side surface portions 223 and 224.

[0046] The container lid 230 is a rectangular plate-like member constituting a lid for the container 210, and is disposed extending in the Y-axis direction on the positive Z-axis side of the container body 220. The container lid 230 is provided with a gas exhaust valve 231 for exhausting gas from inside the container 210 when the internal pressure of the container 210 increases, and a liquid injection part 232 for injecting the electrolyte into the container 210.

[0047] In such a configuration, the container 210 is structured such that the inside is sealed by accommodating the electrode body and the like inside the container body 220, and then the container body 220 and the container lid 230 are joined by welding or the like to form a joint 240. In this embodiment, the container 210 is irradiated with laser light from the sides (X-axis direction and Y-axis direction) of the container 210, and the container body 220 and the container lid 230 are joined by laser welding to form the joint 240. The joint 240 is a quadrangular ring-shaped joint formed to surround the periphery (entire circumference) of the container 210. That is, the joint 240 has a joint 241 located in the positive direction of the X-axis, a joint 242 located in the negative direction of the X-axis, a joint 243 located in the positive direction of the Y-axis, and a joint 244 located in the negative direction of the Y-axis.

[0048] The joint 241 is a joint formed by joining the long side surface portion 221 of the container body 220 and the end of the container lid 230 in the positive direction of the X-axis, and is arranged to extend in the Y-axis direction from one end to the other end of the long side surface portion 221 in the Y-axis direction. The joint 242 is a joint formed by joining the long side surface portion 222 of the container body 220 and the end of the container lid 230 in the negative direction of the X-axis, and is arranged to extend in the Y-axis direction from one end to the other end of the long side surface portion 222 in the Y-axis direction. The joint 243 is a joint formed by joining the short side surface portion 223 of the container body 220 and the end of the container lid 230 in the positive direction of the Y-axis, and is arranged to extend in the X-axis direction from one end to the other end of the short side surface portion 223 in the X-axis direction. The joint 244 is a joint formed by joining the short side portion 224 of the container body 220 and the end portion in the negative Y-axis direction of the container lid body 230, and is arranged to extend in the X-axis direction from one end to the other end of the short side portion 224 in the X-axis direction.

[0049] The joint 241 is formed to have a higher joint strength than at least a part of the joints 240 (joints 242 to 244) other than the joint 241. In this embodiment, the joint 241 is formed to have a higher joint strength than all of the joints 242 to 244. Specifically, the joint 241 is formed to have a higher joint strength than the joints 242 to 244 by forming a deeper penetration depth by welding, such as by increasing the energy density of the irradiated laser light, compared to the joints 242 to 244. For example, the joint strength (penetration depth) of the joint 241 is preferably about 1.1 to 2 times, more preferably about 1.25 to 1.75 times, and even more preferably about 1.4 to 1.5 times, of the joint strength (penetration depth) of the joints 242 to 244.

[0050] [2.2 Explanation of other components] The electrode body is an electric storage element (power generating element) formed by laminating a positive electrode plate, a negative electrode plate, and a separator. The positive electrode plate is a positive electrode active material layer formed on a positive electrode base material layer which is a current collector foil made of a metal such as aluminum or an aluminum alloy. The negative electrode plate is a negative electrode active material layer formed on a negative electrode base material layer which is a current collector foil made of a metal such as copper or a copper alloy. As the active material used in the positive electrode active material layer and the negative electrode active material layer, any known material can be used as long as it can absorb and release lithium ions. The separator can be a microporous sheet or nonwoven fabric made of resin. In this embodiment, the electrode body is formed by laminating electrode plates (positive electrode plate and negative electrode plate) in the X-axis direction. The electrode body may be any type of electrode body, such as a wound type electrode body formed by winding electrode plates (positive electrode plate and negative electrode plate), a stack type electrode body formed by stacking a plurality of flat electrode plates, or a bellows type electrode body in which the electrode plates are folded in a bellows shape.

[0051] The positive electrode terminal 250 and the negative electrode terminal 260 are electrode terminals electrically connected to the positive electrode plate and the negative electrode plate of the electrode body via the positive electrode collector and the negative electrode collector. In other words, the positive electrode terminal 250 and the negative electrode terminal 260 are metal members for leading out electricity stored in the electrode body to the external space of the energy storage element 200 and for introducing electricity into the internal space of the energy storage element 200 to store electricity in the electrode body. The positive electrode terminal 250 and the negative electrode terminal 260 are formed of aluminum, an aluminum alloy, copper, a copper alloy, or the like. The positive electrode terminal 250 and the negative electrode terminal 260 are connected (joined) to the positive electrode collector and the negative electrode collector by crimping, welding, or the like, and are attached to the container lid body 230.

[0052] The positive electrode current collector and the negative electrode current collector are conductive current collecting members electrically connected to the positive electrode terminal 250 and the negative electrode terminal 260 and the electrode body. The positive electrode current collector is made of aluminum or an aluminum alloy, etc., like the positive electrode base layer of the positive electrode plate of the electrode body, and the negative electrode current collector is made of copper or a copper alloy, etc., like the negative electrode base layer of the negative electrode plate of the electrode body.

[0053] The upper gasket 270 is disposed between the container lid 230 and the positive electrode terminal 250 and the negative electrode terminal 260, and is a gasket that insulates and seals between the container lid 230 and the positive electrode terminal 250 and the negative electrode terminal 260. The lower gasket is disposed between the container lid 230 and the positive electrode current collector and the negative electrode current collector, and is a gasket that insulates between the container lid 230 and the positive electrode current collector and the negative electrode current collector. The upper gasket 270 and the lower gasket may be made of any material as long as they have electrical insulation properties.

[0054] [3. Description of the configuration in which the energy storage element 200 is housed in the exterior body 100] Next, a detailed description will be given of the configuration in a state where multiple energy storage elements 200 are housed in exterior body 110 of exterior body 100. Fig. 4 is a plan view showing the configuration in a state where multiple energy storage elements 200 according to the present embodiment are housed in exterior body 110 of exterior body 100. Specifically, Fig. 4 is a top view showing the configuration in a state where eight energy storage elements 200 are housed in exterior body 110, as viewed from the positive direction of the Z axis. That is, Fig. 4 is a top view showing the configuration in a state where exterior body cover 120, bus bar frame 300, and bus bar 400 are removed from energy storage device 10 shown in Fig. 1.

[0055] 4, a plurality of (eight in this embodiment) storage elements 200 are arranged in the X-axis direction (first direction) inside the exterior body 110 of the exterior body 100. As described above, the eight storage elements 200 are arranged such that pairs of storage elements 200 connected in parallel are connected in series. In other words, four sets of storage element groups each made of two storage elements 200 arranged in the X-axis direction in the same orientation are provided, and these four sets of storage element groups are alternately arranged in an orientation rotated 180° around the Z axis (an orientation in which the direction from the positive electrode terminal 250 to the negative electrode terminal 260 is reversed).

[0056] Here, among the multiple storage elements 200, the storage element 200 located at the end in the X-axis positive direction (one side in the first direction) is also referred to as the first storage element 200a. Among the multiple storage elements 200, the storage element 200 located at the end in the X-axis negative direction (the other side in the first direction) is also referred to as the second storage element 200b. As a result, the second storage element 200b is disposed in a position in which the first storage element 200a is rotated 180° around the Z axis. In other words, the first storage element 200a and the second storage element 200b each have a positive terminal 250 and a negative terminal 260, and the first storage element 200a and the second storage element 200b are arranged in opposite directions from the positive terminal 250 to the negative terminal 260. In this embodiment, the direction from positive terminal 250 to negative terminal 260 of first storage element 200a is the negative direction of the Y axis, and the direction from positive terminal 250 to negative terminal 260 of second storage element 200b is the positive direction of the Y axis.

[0057] [3.1 Description of first energy storage element 200a] First, the first energy storage element 200a will be described in detail. The container 210 of the first energy storage element 200a is also referred to as the first container 210a. The long side surface portion 221 of the first container 210a is also referred to as the first long side surface portion 221a, and the long side surface portion 222 of the first container 210a is also referred to as the second long side surface portion 222a. The long side surface of the first container 210a formed by the first long side surface portion 221a is also referred to as the first long side surface, and the long side surface of the first container 210a formed by the second long side surface portion 222a is also referred to as the second long side surface. The short side surface portion 223 of the first container 210a is also referred to as the first short side surface portion 223a, and the short side surface portion 224 of the first container 210a is also referred to as the second short side surface portion 224a. The short side surface of the first container 210a formed by the first short side surface portion 223a is also referred to as the first short side surface, and the short side surface of the first container 210a formed by the second short side surface portion 224a is also referred to as the second short side surface. Among the joints 240 of the first container 210a, the joint 241 is also referred to as the first joint 241a, and the joints 242, 243, and 244 are also referred to as the second joints 242a, 243a, and 244a.

[0058] In this manner, the first energy storage element 200a has a first container 210a in which the container body 220 and the container lid body 230 are joined to form a joint 240. The first container 210a has a first long side surface formed by a first long side surface portion 221a in the positive direction of the X-axis (one side in the first direction), and a second long side surface formed by a second long side surface portion 222a in the negative direction of the X-axis (the other side in the first direction). The first long side surface portion 221a (first long side surface) is disposed opposite the short side wall portion 111 of the exterior body 110, and the second long side surface portion 222a (second long side surface) is disposed opposite the long side surface portion 221 of the container 210 of the energy storage element 200 adjacent to the first energy storage element 200a. The first container 210a has a first short side surface formed by a first short side surface portion 223a in the positive Y-axis direction (one side in the second direction), and a second short side surface formed by a second short side surface portion 224a in the negative Y-axis direction (the other side in the second direction). The first short side surface portion 223a (first short side surface) is disposed opposite the long side wall portion 113 of the exterior body main body 110, and the second short side surface portion 224a (second short side surface) is disposed opposite the long side wall portion 114 of the exterior body main body 110.

[0059] The joint 240 of the first container 210a has a first joint 241a arranged in the positive X-axis direction (one side of the first direction) and extending in the Y-axis direction (second direction). The joint 240 of the first container 210a has second joints 242a, 243a, and 244a arranged in a direction different from the positive X-axis direction (one side of the first direction) (i.e., the negative X-axis direction, the positive Y-axis direction, and the negative Y-axis direction). The second joint 242a is arranged in the negative Y-axis direction (second direction), and the second joints 243a and 244a are arranged in the positive X-axis direction (first direction). The first joint 241a is arranged on the first long side surface of the first container 210a, and the second joint 242a is arranged on the second long side surface of the first container 210a. The second joint portion 243a is disposed on a first short side surface of the first container 210a, and the second joint portion 244a is disposed on a second short side surface of the first container 210a.

[0060] The first bonding portion 241a includes a central portion in the Y-axis direction (second direction) of the bonding portion 240 located in the X-axis positive direction (one side in the first direction) of the first container 210a, and is arranged to extend over a length of more than half the width of the first container 210a in the Y-axis direction (second direction). In this embodiment, the first bonding portion 241a is arranged to extend in the Y-axis direction from one end to the other end of the bonding portion 240 located in the X-axis positive direction of the first container 210a. In addition, the first bonding portion 241a has a higher bonding strength than the second bonding portions 242a, 243a, and 244a. For example, the first bonding portion 241a has a deeper penetration depth by welding than the second bonding portions 242a, 243a, and 244a, and therefore has a higher bonding strength than the second bonding portions 242a, 243a, and 244a.

[0061] [3.2 Description of second energy storage element 200b] Next, the second energy storage element 200b will be described in detail. The container 210 of the second energy storage element 200b is also referred to as the second container 210b. The long side surface portion 221 of the second container 210b is also referred to as the third long side surface portion 221b, and the long side surface portion 222 of the second container 210b is also referred to as the fourth long side surface portion 222b. The long side surface of the second container 210b formed by the third long side surface portion 221b is also referred to as the third long side surface, and the long side surface of the second container 210b formed by the fourth long side surface portion 222b is also referred to as the fourth long side surface. The short side surface portion 223 of the second container 210b is also referred to as the third short side surface portion 223b, and the short side surface portion 224 of the second container 210b is also referred to as the fourth short side surface portion 224b. The short side surface of the second container 210b formed by the third short side surface portion 223b is also referred to as the third short side surface, and the short side surface of the second container 210b formed by the fourth short side surface portion 224b is also referred to as the fourth short side surface. Among the joints 240 of the second container 210b, the joint 241 is also referred to as the third joint 241b, and the joints 242, 243, and 244 are also referred to as the fourth joints 242b, 243b, and 244b.

[0062] In this manner, the second energy storage element 200b has a second container 210b in which the container body 220 and the container lid body 230 are joined to form a joint 240. The second container 210b has a third long side surface formed by the third long side surface portion 221b in the negative X-axis direction (the other side in the first direction), and a fourth long side surface formed by the fourth long side surface portion 222b in the positive X-axis direction (one side in the first direction). The third long side surface portion 221b (third long side surface) is disposed opposite the short side wall portion 112 of the exterior body 110, and the fourth long side surface portion 222b (fourth long side surface) is disposed opposite the long side surface portion 221 of the container 210 of the energy storage element 200 adjacent to the second energy storage element 200b. The second container 210b has a third short side surface formed by the third short side surface portion 223b in the negative Y-axis direction (the other side in the second direction), and a fourth short side surface formed by the fourth short side surface portion 224b in the positive Y-axis direction (one side in the second direction). The third short side surface portion 223b (third short side surface) is disposed opposite the long side wall portion 114 of the exterior body main body 110, and the fourth short side surface portion 224b (fourth short side surface) is disposed opposite the long side wall portion 113 of the exterior body main body 110.

[0063] The joint 240 of the second container 210b has a third joint 241b arranged in the negative X-axis direction (the other side of the first direction) and extending in the Y-axis direction (second direction). The joint 240 of the second container 210b has fourth joints 242b, 243b, and 244b arranged in a direction different from the negative X-axis direction (the other side of the first direction) (i.e., the positive X-axis direction, the positive Y-axis direction, and the negative Y-axis direction). The fourth joint 242b is arranged in the positive Y-axis direction (second direction), and the fourth joints 243b and 244b are arranged in the positive X-axis direction (first direction). The third joint 241b is arranged on the third long side surface of the second container 210b, and the fourth joint 242b is arranged on the fourth long side surface of the second container 210b. The fourth joint portion 243b is disposed on a third short side surface of the second container 210b, and the fourth joint portion 244b is disposed on a fourth short side surface of the second container 210b.

[0064] The third bonding portion 241b includes a central portion in the Y-axis direction (second direction) of the bonding portion 240 located in the negative X-axis direction (the other side of the first direction) of the second container 210b, and is arranged to extend over a length of more than half the width of the second container 210b in the Y-axis direction (second direction). In this embodiment, the third bonding portion 241b is arranged to extend in the Y-axis direction from one end to the other end of the bonding portion 240 located in the negative X-axis direction of the second container 210b. In addition, the third bonding portion 241b has a higher bonding strength than the fourth bonding portions 242b, 243b, and 244b. For example, the third bonding portion 241b has a deeper penetration depth by welding than the fourth bonding portions 242b, 243b, and 244b, and therefore has a higher bonding strength than the fourth bonding portions 242b, 243b, and 244b.

[0065] [4. Description of Effects] As described above, according to the energy storage device 10 of the embodiment of the present invention, the first energy storage element 200a is disposed at an end portion on one side in the first direction (positive direction of the X-axis) among the plurality of energy storage elements 200. Among the joint portions 240 of the first container 210a of the first energy storage element 200a, the first joint portion 241a extending in the second direction (Y-axis direction) on one side in the first direction has a higher joint strength than the second joint portions 242a, 243a, or 244a on a side in a direction different from the one side in the first direction. Here, in the energy storage device 10, in a configuration in which the plurality of energy storage elements 200 are arranged in the first direction (X-axis direction), among the joint portions 240 of the first container 210a of the first energy storage element 200a at the end portion on one side in the first direction, the joint portion 240 on one side in the first direction is easily damaged. For this reason, among the joints 240 of the first container 210a in the first energy storage element 200a, the first joint 241a extending in the second direction on one side of the first direction is made to have a higher joint strength than the second joints 242a, 243a, or 244a on the other side of the first direction. That is, the joint strength of the first joint 241a, which is relatively easily damaged, is made higher than the joint strength of the second joints 242a, 243a, or 244a, which are relatively less likely to be damaged. This reduces the risk of defects occurring compared to increasing the joint strength of both the first joint 241a and the second joint 242a, 243a, or 244a, and can increase the joint strength at the necessary locations, thereby suppressing damage to the energy storage element 200. In addition, by suppressing the expansion of the first container 210a of the first energy storage element 200a, it is also possible to suppress the expansion of the first container 210a and damage to the exterior body 100 (exterior body main body 110).

[0066] Of the joints 240 of the first container 210a of the first energy storage element 200a, the first joints 241a extend over a length equal to or greater than half the width of the first container 210a in the second direction (Y-axis direction), thereby making it possible to further increase the joint strength of the joints 240 on one side of the first container 210a in the first direction. This makes it possible to further prevent damage to the energy storage element 200 and the exterior body 100.

[0067] In the first energy storage element 200a, when the first container 210a swells, a central portion in the second direction of the joint 240 located on one side of the first container 210a in the first direction swells and is likely to be damaged. For this reason, the first joint 241a, which has high joint strength, is disposed so as to extend to include the central portion. This makes it possible to increase the joint strength of the easily damaged portion of the joint 240, thereby making it possible to further prevent damage to the energy storage element 200. In addition, since the joint strength of the easily swelled portion of the joint 240 can be increased, it is possible to further prevent damage to the exterior body 100.

[0068] In the energy storage device 10, the second energy storage element 200b is disposed at an end portion on the other side in the first direction (negative direction of the X-axis) of the multiple energy storage elements 200. Among the joint portions 240 of the second container 210b of the second energy storage element 200b, a third joint portion 241b extending in the second direction (Y-axis direction) on the other side in the first direction has a higher joint strength than a fourth joint portion 242b, 243b or 244b on a side in a direction different from the other side in the first direction. Here, in the energy storage device 10, among the joint portions 240 of the second container 210b of the second energy storage element 200b at the end portion on the other side in the first direction of the multiple energy storage elements 200, the joint portion 240 on the other side in the first direction is also easily damaged. For this reason, among the joints 240 of the second container 210b in the second energy storage element 200b, the third joint 241b extending in the second direction on the other side of the first direction is made to have a higher joint strength than the fourth joint 242b, 243b, or 244b on the other side of the first direction. That is, the joint strength of the third joint 241b, which is relatively easily damaged, is made higher than the joint strength of the fourth joint 242b, 243b, or 244b, which is relatively less likely to be damaged. This reduces the risk of a defect occurring compared to increasing the joint strength of both the third joint 241b and the fourth joint 242b, 243b, or 244b, and can increase the joint strength at the necessary location, thereby suppressing damage to the energy storage element 200. In addition, by suppressing the expansion of the second container 210b of the second energy storage element 200b, it is also possible to suppress the expansion of the second container 210b and damage to the exterior body 100 (exterior body main body 110).

[0069] In the first energy storage element 200a, the bonding strength of the first joint 241a on one side in the first direction is made high, and in the second energy storage element 200b, the bonding strength of the third joint 241b on the other side in the first direction is made high. That is, the first energy storage element 200a and the second energy storage element 200b have an inverse relationship in terms of bonding strength in the first direction. Therefore, by arranging the positive electrode terminal 250 and the negative electrode terminal 260 of the first energy storage element 200a and the second energy storage element 200b in the opposite direction (the direction from the positive electrode terminal 250 to the negative electrode terminal 260 is the opposite direction), the first energy storage element 200a and the second energy storage element 200b have a relationship rotated by 180 degrees. As a result, the energy storage element 200 having the same configuration can be utilized as the first energy storage element 200a and the second energy storage element 200b, and therefore a configuration that suppresses damage to the energy storage element 200 can be easily realized.

[0070] In the first energy storage element 200a, when the first container 210a has a first long side surface (first long side surface portion 221a) on one side in the first direction and a second long side surface (second long side surface portion 222a) on the other side in the first direction, the joint 240 on the first long side surface side is easily damaged. In contrast, the second long side surface presses against the long side surface of the container 210 of the adjacent energy storage element 200, so that the joint 240 on the second long side surface side is not easily damaged. For this reason, by arranging the first joint 241a on the first long side surface side of the first container 210a and the second joint 242a on the second long side surface side of the first container 210a, the joint strength of the first joint 241a, which is relatively easily damaged, is made higher than the joint strength of the second joint 242a, which is relatively less easily damaged. This makes it possible to effectively prevent the energy storage element 200 from being damaged.

[0071] In the first container 210a of the first energy storage element 200a, the first bonding portion 241a is welded to a greater depth than the second bonding portions 242a, 243a, or 244a, so that the bonding strength of the first bonding portion 241a can be easily made higher than the bonding strength of the second bonding portions 242a, 243a, or 244a. This makes it possible to easily prevent the energy storage element 200 from being damaged.

[0072] [5. Explanation of Variations] (Variation 1) Next, a first modification of the above embodiment will be described. Fig. 5 is a plan view showing a configuration in which a plurality of energy storage elements 200 according to the first modification of the present embodiment are housed in exterior body 110 of exterior body 100. Specifically, Fig. 5 is a view corresponding to Fig. 4.

[0073] 5, in this modification, the multiple (eight) energy storage elements 200 housed in the exterior body 110 are all arranged so as to be connected in series. That is, the eight energy storage elements 200 are arranged alternately in a position rotated 180° around the Z axis (a position in which the direction from the positive electrode terminal 250 to the negative electrode terminal 260 is reversed). The rest of the configuration is the same as in the above embodiment, and therefore detailed description will be omitted.

[0074] As described above, the energy storage device according to this modification can achieve the same effects as those of the above embodiment. In this manner, the energy storage elements 200 other than the first energy storage element 200a and the second energy storage element 200b may be arranged in any posture. In other words, as long as the postures of the first energy storage element 200a and the second energy storage element 200b are maintained, the connection form (parallel connection, series connection) of the multiple energy storage elements 200 may be any.

[0075] (Variation 2) Next, a second modification of the above embodiment will be described. Fig. 6 is a plan view showing a configuration in which a plurality of energy storage elements 201 according to the second modification of the present embodiment are housed in exterior body 110 of exterior body 100. Specifically, Fig. 6 is a view corresponding to Fig. 4.

[0076] As shown in Fig. 6, in this modification, an energy storage element 201 is arranged instead of the energy storage element 200 in the above embodiment. The energy storage element 201 has a joint 240 formed on a surface of the container 210 in the positive direction of the Z axis. That is, the container lid 230 is housed in the container body 220, and, for example, a laser beam is irradiated from the positive direction of the Z axis of the container 210 to join the container body 220 and the container lid 230 by laser welding, thereby forming the joint 240. The other configurations are similar to those of the above embodiment, and therefore detailed description thereof will be omitted.

[0077] As described above, the energy storage device according to this modification can achieve the same effects as those of the above embodiment. In this manner, the same configuration as that of the above embodiment can be applied to the energy storage element 201 in which the joint 240 is formed on the surface of the container 210 in the positive direction of the Z axis.

[0078] (Variation 3) Next, a third modification of the above embodiment will be described. Fig. 7 is a perspective view showing a configuration of an energy storage element 202 according to the third modification of the present embodiment. Specifically, Fig. 7 corresponds to Fig. 3.

[0079] 7, in this modification, the energy storage element 202 has a joint 245 and two joints 246 disposed on both sides in the Y-axis direction of the joint 245, instead of the joint 241 of the energy storage element 200 in the above embodiment. Since the other configurations are similar to those of the above embodiment, detailed description thereof will be omitted.

[0080] The joint 245 is disposed including a central portion in the Y-axis direction of the joint 240 in the positive X-axis direction of the container 210, and extends over a length of at least half the width of the container 210 in the Y-axis direction. The first joint 241a is more preferably extended over a length of at least ⅔ of the width of the container 210, and further preferably extended over a length of at least ¾ of the width of the container 210. The joint 245 is formed to have a higher bonding strength than the joints 240 (joints 242-244 and 246) other than the joint 245, like the joint 241 in the above embodiment. The joint 246 has a bonding strength equivalent to that of the joints 242-244.

[0081] That is, in this modification, in the first container 210a, the joint 245 corresponds to the first joint 241a in the above embodiment, and in the second container 210b, the joint 245 corresponds to the third joint 241b in the above embodiment. Thus, in this modification, the first joint 241a is arranged to extend over a length that is half or more of the width in the Y-axis direction (second direction) of the first container 210a and less than the entire length. Also, in this modification, the first joint 241a is arranged to extend including the center in the Y-axis direction (second direction) of the joint 240 located in the X-axis positive direction (one side in the first direction) of the first container 210a. The same applies to the third joint 241b.

[0082] As described above, the energy storage device according to this modification can achieve the same effects as those of the above embodiment. In this manner, the first bonding portion 241a or the third bonding portion 241b does not have to be formed over the entire width of the container 210 in the Y-axis direction.

[0083] (Variation 4) Next, a fourth modification of the above embodiment will be described. Fig. 8 is a plan view showing a configuration in which a plurality of energy storage elements 203 according to the fourth modification of the present embodiment are housed in exterior body 110 of exterior body 100. Specifically, Fig. 8 is a view corresponding to Fig. 4.

[0084] As shown in FIG. 8, in this modification, unlike the energy storage element 200 in the above embodiment, the energy storage element 203 is arranged side by side in the X-axis direction so that the short side surfaces of the container 210 of adjacent energy storage elements 203 face each other. As a result, the positive electrode terminal 250 and the negative electrode terminal 260 of the energy storage element 203 are arranged side by side in the X-axis direction. That is, the energy storage element 203 has a configuration in which the long side surface portions 221 and 222 and the short side surface portions 223 and 224 of the container 210 in the above embodiment are interchanged. Specifically, in the energy storage element 203, the joint portions 241 and 242 are provided on the short side surface portions 223 and 224 sides of the container 210, and the joint portions 243 and 244 are provided on the long side surface portions 221 and 222 sides of the container 210.

[0085] That is, in the first energy storage element 203a, the first joint portion 241a is arranged on the first short side surface (first short side surface portion 223a) of the first container 210a, and the second joint portion 242a is arranged on the second short side surface (second short side surface portion 224a) of the first container 210a. The second joint portions 243a and 244a are arranged on the first long side surface (first long side surface portion 221a) and second long side surface (second long side surface portion 222a) of the first container 210a. In the second energy storage element 203b, the third joint portion 241b is arranged on the third short side surface (third short side surface portion 223b) of the second container 210b, and the fourth joint portion 242b is arranged on the fourth short side surface (fourth short side surface portion 224b) of the second container 210b. The fourth bonding portions 243b and 244b are disposed on the third long side surface (third long side surface portion 221b) and the fourth long side surface (fourth long side surface portion 222b) of the second container 210b.

[0086] The second storage element 203b is disposed in a position rotated 180° around the Z axis from the first storage element 203a. That is, the first storage element 203a and the second storage element 203b each have a positive terminal 250 and a negative terminal 260, and the first storage element 203a and the second storage element 203b are opposite in direction from the positive terminal 250 to the negative terminal 260. In this modification, the direction from the positive terminal 250 to the negative terminal 260 of the first storage element 203a is the negative direction of the X axis, and the direction from the positive terminal 250 to the negative terminal 260 of the second storage element 203b is the positive direction of the X axis. The other configurations are the same as those of the above embodiment, and therefore detailed description thereof will be omitted.

[0087] As described above, according to the energy storage device of this modification, it is possible to obtain the same effects as those of the above-described embodiment. In this manner, the first bonding portion 241a and the third bonding portion 241b may be disposed on the short side surface of the container 210.

[0088] (Other variations) Although the power storage device according to the present embodiment (including its modified examples) has been described above, the present invention is not limited to the above-described embodiment. In other words, the embodiment disclosed herein is illustrative and not restrictive in all respects, and the scope of the present invention includes all modifications within the meaning and scope equivalent to the claims.

[0089] For example, in the above embodiment, the joint 240 is a joint formed by laser welding. However, the joint 240 may be a joint formed by a means other than laser welding, such as resistance welding, ultrasonic bonding, heat welding, adhesion, bolt fastening, crimping, etc. In this case, the joint strength is not limited to being increased by deepening the penetration depth by welding, and the joint strength may be increased by any means.

[0090] In the above embodiment, the joint 241 (or 245) extends over a length equal to or greater than half the width in the second direction (Y-axis direction) of the container 210. However, the joint 241 (or 245) may extend over a length less than half the width in the second direction (Y-axis direction) of the container 210.

[0091] In the above embodiment, the joint 241 (or 245) is arranged at a position including the center in the second direction (Y-axis direction) of the joint 240. However, the joint 241 (or 245) may be arranged at a position slightly deviated from the center.

[0092] In the above embodiment, all of the multiple energy storage elements 200 have the same configuration, but any of the energy storage elements 200 may not have the above configuration. For example, the energy storage elements 200 other than the first energy storage element 200a and the second energy storage element 200b may not have the above configuration, and the second energy storage element 200b may not have the above configuration.

[0093] In the above embodiment, the first energy storage element 200a and the second energy storage element 200b are arranged in opposite directions from the positive electrode terminal 250 to the negative electrode terminal 260. However, the first energy storage element 200a and the second energy storage element 200b may be arranged in the same direction from the positive electrode terminal 250 to the negative electrode terminal 260.

[0094] In the above-described embodiment, the power storage device does not need to include all of the components. For example, the power storage device does not need to include the exterior body 100 or the bus bar frame 300.

[0095] Any combination of the components included in the above-described embodiment and its modified examples is also included within the scope of the present invention.

[0096] The present invention can be realized not only as such an electricity storage device, but also as a plurality of electricity storage elements. [Industrial Applicability]

[0097] The present invention can be applied to an electricity storage device including an electricity storage element such as a lithium ion secondary battery. [Explanation of symbols]

[0098] 10. Energy storage device 100 Exterior body 110 Exterior body 111, 112 Short side wall 113, 114 Long side wall 120 Exterior body cover 200, 201, 202, 203 Energy storage element 200a, 203a First storage element 200b, 203b Second storage element 210 Container 210a First container 210b Second container 220 Container body 221, 222 Long side part 221a First long side part 221b Third long side part 222a Second long side part 222b Fourth long side part 230 Container lid 240, 241, 242, 243, 244, 245, 246 joint 241a First joint 241b Third joint 242a, 243a, 244a Second joint 242b, 243b, 244b Fourth joint 250 Positive terminal 260 negative terminal 270 Upper Gasket 300 Busbar Frame 400, 410, 420, 430 Busbars

Claims

1. A power storage device including a plurality of power storage elements arranged in a first direction, a first energy storage element located at an end on one side of the first direction among the plurality of energy storage elements includes a first container having a container body and a lid body joined to form a joint portion, the joint portion of the first container has a first joint portion arranged on one side of the first direction to extend in a second direction intersecting the first direction, and a second joint portion arranged on both the one side and the other side of the second direction, The first bonded portion has a higher bond strength than the second bonded portion. Energy storage device.

2. A power storage device including a plurality of power storage elements arranged in a first direction, a first energy storage element located at an end on one side of the first direction among the plurality of energy storage elements includes a first container having a container body and a lid body joined to form a joint portion, the joint portion of the first container has a first joint portion arranged on one side of the first direction to extend in a second direction intersecting the first direction, and a second joint portion arranged on a side in a direction different from the one side of the first direction, The first bonding portion has a bonding strength higher than that of the second bonding portion, a second energy storage element located at an end portion on the other side in the first direction among the plurality of energy storage elements includes a second container having a container body and a lid body joined to form a joint portion, the joint portion of the second container has a third joint portion arranged on the other side of the first direction to extend in the second direction, and a fourth joint portion arranged on a side in a direction different from the other side of the first direction, The third bonded portion has a bond strength higher than that of the fourth bonded portion. Energy storage device.

3. Each of the first storage element and the second storage element has a positive terminal and a negative terminal, The first storage element and the second storage element are arranged in opposite directions from the positive terminal to the negative terminal. The power storage device according to claim 2 .

4. A power storage device including a plurality of power storage elements arranged in a first direction, a first energy storage element located at an end on one side of the first direction among the plurality of energy storage elements includes a first container having a container body and a lid body joined to form a joint portion, the joint portion of the first container has a first joint portion arranged on one side of the first direction to extend in a second direction intersecting the first direction, and a second joint portion arranged on a side in a direction different from the one side of the first direction, The first bonding portion extends over the entire length of the first container in the second direction and has a bonding strength higher than that of the second bonding portion. Energy storage device.

5. A power storage device including a plurality of power storage elements arranged in a first direction, a first energy storage element located at an end on one side of the first direction among the plurality of energy storage elements includes a first container having a container body and a lid body joined to form a joint portion, the joint portion of the first container has a first joint portion arranged on one side of the first direction to extend in a second direction intersecting the first direction, and a second joint portion arranged on a side in a direction different from the one side of the first direction, The first bonding portion has a bonding strength higher than that of the second bonding portion, Among the plurality of storage elements, a storage element located on the other side of the first storage element in the first direction has a different configuration from the first storage element. Energy storage device.

6. The first joint portion is disposed so as to extend over a length equal to or greater than half of the width of the first container in the second direction. The power storage device according to any one of claims 1 to 3 and 5.

7. The first joint portion is disposed to extend to include a central portion in the second direction of a joint portion located on one side of the first container in the first direction. The power storage device according to any one of claims 1 to 3, 5 and 6.

8. The first joint has a greater penetration depth by welding than the second joint. The power storage device according to any one of claims 1 to 7.

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