Power storage device

Abstract

To provide a power storage device which can suppress damage of a seal part for sealing a collector electrode of a capacitor cell by heat during joining, when a wiring cable is joined to the collector electrode of the capacitor cell.SOLUTION: A power storage device includes a first power storage element and a second power storage element which are aligned in a first direction X, and a detection line for detecting the states of the first power storage element and the second power storage element, wherein the first power storage element includes a first enclosure and a first tab part 222 projecting from the edge part of the first enclosure, the second power storage element includes a second tab part 221 which is superposed and connected to the first tab part, the edge part of the first enclosure includes a seal part for sealing the edge part and the first tab part, the detection line includes a joint part 361 which is joined to the first tab part at a position between the center of the projection length of the first tab part and the tip of the first tab part, and thermal conductivity of the first tab part is higher than thermal conductivity of the second tab part.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] Patent Document 1 discloses an electricity storage system in which a housing contains an electricity storage unit formed by assembling a plurality of capacitor cells on a frame. In this electricity storage system, a wiring cable is connected to a collector electrode connector connected to the collector electrode of the capacitor cell. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-110035 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, when the distribution cable is joined to the collector electrode of the capacitor cell, heat generated during joining is transferred to the capacitor cell, and there is a risk that the seal portion that seals the collector electrode of the capacitor cell may be damaged.

[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 that can suppress damage to the sealing portion. [Means for solving the problem]

[0006] A storage device according to one embodiment of the present invention comprises a first storage element and a second storage element arranged in a first direction, and a detection line for detecting the state of the first storage element and the second storage element, wherein the first storage element comprises a first outer casing and a first tab portion protruding from an edge of the first outer casing, the second storage element comprises a second tab portion overlapping and connected to the first tab portion, the edge of the first outer casing comprises a sealing portion sealing the edge and the first tab portion, the detection line comprises a joint portion joined to the first tab portion at a position between the center of the protruding length of the first tab portion and the tip of the first tab portion, and the thermal conductivity of the first tab portion is higher than the thermal conductivity of the second tab portion. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an electricity storage device that can suppress damage to the sealing portion. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing the appearance of a power storage device according to an embodiment. [Figure 2] FIG. 2 is an exploded perspective view showing each component of the electricity storage device according to the embodiment. [Figure 3] FIG. 3 is a perspective view showing a plurality of energy storage elements according to the embodiment in a separated state. [Figure 4] FIG. 4 is a perspective view showing a joining structure between a detection wire and a lead terminal according to the embodiment. [Figure 5] FIG. 5 is a plan view showing the positional relationship between the joint portion and the flat plate portion according to the embodiment. [Figure 6] FIG. 6 is a plan view showing a flat plate portion and a flat plate portion according to the first modification. [Figure 7] FIG. 7 is a plan view showing a flat plate portion and a flat plate portion according to the second modification. [Figure 8] FIG. 8 is a plan view showing a flat plate portion and a flat plate portion according to the third modification. [Figure 9] FIG. 9 is a side view showing a negative electrode lead terminal and a positive electrode lead terminal according to the fourth modification. [Figure 10] FIG. 10 is a side view showing a negative electrode lead terminal and a positive electrode lead terminal according to the fifth modification. DETAILED DESCRIPTION OF THE INVENTION

[0009] (1) A storage device according to one embodiment of the present invention comprises a first storage element and a second storage element aligned in a first direction, and a detection line for detecting the state of the first storage element and the second storage element, wherein the first storage element comprises a first outer casing and a first tab portion protruding from an edge of the first outer casing, the second storage element comprises a second tab portion overlapping and connected to the first tab portion, the edge of the first outer casing comprises a sealing portion sealing the edge and the first tab portion, the detection line comprises a joint portion joined to the first tab portion at a position between the center of the protruding length of the first tab portion and the tip of the first tab portion, and the thermal conductivity of the first tab portion is higher than the thermal conductivity of the second tab portion.

[0010] According to the energy storage device described in (1) above, the position between the center of the protruding length of the first tab portion and the tip end of the first tab portion is located away from the sealed portion. Since the joining portion of the detection line is joined to the first tab portion at this position, the heat transfer path to the sealed portion can be lengthened. Therefore, heat generated during joining is less likely to be transferred to the sealed portion, and damage to the sealed portion can be suppressed.

[0011] (2) In the energy storage device described in (1) above, the second tab portion may have a shape that does not overlap the joint portion when viewed from a direction in which the first tab portion and the second tab portion overlap.

[0012] According to the energy storage device described in (2) above, the second tab portion has a shape that does not overlap the joining portion when viewed from the direction in which the first tab portion and the second tab portion overlap, so the second tab portion is less likely to get in the way when joining the detection line, thereby improving the workability of the joining operation.

[0013] (3) In the energy storage device described in (1) or (2) above, the first tab portion may include a first bent portion bent toward the second energy storage element and a first flat portion facing a second direction intersecting the first direction, and the second tab portion may include a second bent portion bent toward the first energy storage element and a second flat portion facing the second direction.

[0014] According to the energy storage device described in (3) above, the first tab portion is bent toward the second energy storage element, and the second tab portion is bent toward the first energy storage element. Therefore, the first flat plate portion and the second flat plate portion face the second direction, so the dimension of the energy storage device in the second direction can be reduced. In other words, even when the first tab portion and the second tab portion are bent, there are few restrictions on the joining of the joint portion of the detection line to the first tab portion.

[0015] (4) In the electricity storage device described in (3) above, the joint portion may be disposed on the first flat plate portion.

[0016] According to the energy storage device described in (4) above, since the joint portion is disposed on the first flat plate portion, the detection line and the first tab portion can be joined on the second direction side, and therefore the first energy storage element and the second energy storage element aligned in the first direction can be stably joined without interfering with the joining operation.

[0017] (5) In the energy storage device described in (3) or (4) above, the second flat plate portion may be disposed further outward in the second direction than the first flat plate portion when viewed from the first direction.

[0018] According to the electric storage device described in (5) above, the second flat plate portion is disposed further outward in the second direction than the first flat plate portion when viewed from the first direction, so that the amount of protrusion of the detection line and the joint portion in the second direction can be reduced, which means that the dimension of the electric storage device in the second direction can be further reduced.

[0019] (6) In the energy storage device described in any one of (1) to (5) above, the detection line may extend in the first direction, pass through the joint, and then be folded back to reach the joint.

[0020] According to the energy storage device described in (6) above, the detection wire extends in the first direction, passes through the joint, and is folded back to reach the joint. This results in an excess length of the detection wire. Because the first direction is the direction in which the first and second storage elements are aligned, the lengths of the first and second storage elements in the first direction are likely to vary during manufacturing. Furthermore, the first and second storage elements may expand in the first direction during use. That is, the lengths of the first and second storage elements in the first direction may become larger or smaller than a set value during manufacturing or use. In particular, if the lengths of the first and second storage elements in the first direction become larger or smaller than a set value, the detection wire may be pulled in the first direction, potentially damaging the joint. Therefore, providing an excess length of the detection wire makes it easier to position the detection wire during joining, thereby improving the workability of the joining operation. Furthermore, even if the detection wire is pulled, the excess length of the detection wire deforms, thereby reducing damage to the joint.

[0021] (Embodiment) Hereinafter, with reference to the drawings, a description will be given of an energy storage device according to an embodiment of the present invention (including modifications thereof). Note that the embodiments described below all show comprehensive or specific examples. The numerical values, shapes, materials, components, component placement positions and connection forms shown in the following embodiments are examples and are not intended to limit the present invention. In each drawing, dimensions and the like are not strictly illustrated. In each drawing, the same reference numerals are used for identical or similar components. The names of the components (each component) in this embodiment are those used in this embodiment and may differ from the names of the components (each component) in the background art.

[0022] In the following description and drawings, the X-axis direction is defined as the arrangement direction of the exterior body and exterior body lid in the exterior body of the energy storage device, or the arrangement direction of multiple energy storage elements included in the energy storage device. The Y-axis direction is defined as the protruding direction of each lead terminal of an energy storage element. The Z-axis direction is defined as the arrangement direction of a pair of lead terminals included in an energy storage element, or the up-down direction. The X-axis direction, Y-axis direction, and Z-axis direction intersect with each other (orthogonal in the following embodiments and their modifications). The X-axis direction is an example of a first direction, and the Y-axis direction is an example of a second direction. 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 as the up-down direction below. In the following description, the positive X-axis direction refers to the direction of the arrow on the X-axis, and the negative X-axis direction refers to the opposite side of the positive X-axis direction. The same applies to the Y-axis direction and the Z-axis direction. Furthermore, expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the directions or attitudes are not strictly those. "Two directions are perpendicular" does not only mean that the two directions are completely perpendicular, but also that they are substantially perpendicular, that is, that there is a difference of a few percent. In the following explanation, when the term "insulation" is used, it means "electrical insulation." An insulating material has a volume resistivity of 1×10 6 Ωm or more, more preferably 1×10 7 Ωm or more, more preferably 1×10 10 It is preferable that the material be made of a material with a resistance of Ωm or more.

[0023] [General explanation of the power storage device] First, an overall description of a power storage device 1 according to an embodiment will be given with reference to Figures 1 and 2. Figure 1 is a perspective view showing the appearance of the power storage device 1 according to an embodiment. Figure 2 is an exploded perspective view showing each component of the power storage device 1 according to an embodiment.

[0024] The power storage device 1 is a device capable of charging with electricity from an external source and discharging electricity to the outside, and in this embodiment, has a rectangular parallelepiped shape. A rectangular parallelepiped is a hexahedron with all faces formed of rectangles or squares. The power storage device 1 is a battery module (battery assembly) used for power storage, power supply, etc. 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 may be used as a stationary battery for home or business use.

[0025] 1 and 2, the energy storage device 1 includes an energy storage unit 20 and an exterior body 10 that houses the energy storage unit 20. The exterior body 10 includes an exterior body main body 11 that houses the energy storage unit 20, and an exterior body lid body 12 that covers the exterior body main body 11.

[0026] The exterior body 10 is a rectangular (box-shaped) container (module case) that constitutes the exterior body of the energy storage device 1. In other words, the exterior body 10 is a member that fixes the energy storage unit 20 and the like in predetermined positions and protects these elements from impacts and the like.

[0027] The exterior body main body 11 is a rectangular cylindrical member with a bottom that is open in the positive direction of the X axis, and the open portion is an opening 111. The opening 111 has a quadrangular shape in a plan view (as viewed in the X axis direction). In addition to the power storage unit 20, the opening 111 of the exterior body main body 11 accommodates a plurality of bus bars (not shown) and fuses (not shown) held by the power storage unit 20.

[0028] The exterior body lid 12 is a member that closes the opening 111 of the exterior body main body 11, and is joined to the exterior body main body 11 in a state in which the opening 111 of the exterior body main body 11 is closed from the positive direction of the X axis. A circuit board 35 is disposed outside the opening 111 at a position corresponding to the exterior body lid 12. In other words, the circuit board 35 is housed between the exterior body main body 11 and the exterior body lid 12. The exterior body lid 12 has a pair of external terminals 81 (positive and negative electrodes). The external terminals 81 are electrically connected to the multiple energy storage elements 21 included in the energy storage unit 20 via the bus bars, fuses, and circuit board 35. The energy storage device 1 charges with electricity from the outside and discharges electricity to the outside via these external terminals 81. The external terminals 81 are formed of a conductive member made of a metal such as copper, a copper alloy, aluminum, an aluminum alloy, or nickel, or a combination thereof, or a conductive member other than a metal.

[0029] Here, each bus bar is a plate-like member that electrically connects external terminals 81 and energy storage elements 21. Each bus bar is formed of a conductive member made of metal such as copper, copper alloy, aluminum, aluminum alloy, or nickel, or a combination thereof, or a conductive member other than metal.

[0030] The fuse is a component that protects circuit board 35, power storage elements 21, etc. from a current greater than the rated current. When a current greater than the rated current flows, the fuse melts to interrupt the flow of current.

[0031] The circuit board 35 has multiple electrical components (not shown), and these multiple electrical components form a detection circuit that detects the state (temperature, voltage, current, etc.) of each storage element 21, and a control circuit that controls charging and discharging.

[0032] The exterior body 11 and exterior body lid 12 of the exterior body 10 are formed from insulating materials such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), 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), polyethersulfone (PES), polyamide (PA), ABS resin, or composite materials thereof, or from metals or the like with an insulating coating. This prevents the energy storage elements 21 and the like from coming into contact with external metal members or the like. Note that the exterior body 10 may be formed from a conductive material such as metal as long as the electrical insulation of the energy storage elements 21 and the like is maintained. Exterior body 11 and exterior body lid 12 may be made of the same material or different materials.

[0033] [Energy storage unit] The electricity storage unit 20 includes a plurality of electricity storage elements 21 and a holding member 22.

[0034] The energy storage element 21 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. In this embodiment, the energy storage element 21 is a pouch-type energy storage element having a flat shape, and a plurality of (four in this embodiment) pouch-type energy storage elements 21 are arranged side by side in the X-axis direction. The energy storage element 21 is not limited to a pouch-type energy storage element, and may be an energy storage element having a flat rectangular parallelepiped (square shape), a polygonal prism shape other than a rectangular parallelepiped, a cylindrical shape, an elongated cylindrical shape, or an elliptical cylindrical shape, and the size and shape thereof are not limited. The number of energy storage elements 21 arranged is also not particularly limited. The energy storage element 21 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than a non-aqueous electrolyte secondary battery, a capacitor, or a battery using a solid electrolyte. The energy storage element 21 may be a primary battery instead of a secondary battery. The plurality of energy storage elements 21 are arranged in the X-axis direction, and adjacent energy storage elements 21 may or may not be joined together with an adhesive or double-sided tape. Details of energy storage elements 21 will be described later.

[0035] The holding member 22 is a member that holds the multiple energy storage elements 21. The holding member 22 includes a first holding member 23 and a second holding member 24 that holds the multiple energy storage elements 21 together with the first holding member 23. Specifically, the first holding member 23 is arranged in the negative X-axis direction of the multiple energy storage elements 21 and is bonded to an energy storage element 21 that is arranged at an end of the multiple energy storage elements 21 in the negative X-axis direction with an adhesive or double-sided tape. The second holding member 24 is arranged in the positive X-axis direction of the multiple energy storage elements 21 and is bonded to an energy storage element 21 that is arranged at an end of the multiple energy storage elements 21 in the positive X-axis direction with an adhesive or double-sided tape. As a result, the first holding member 23 and the second holding member 24 hold the multiple energy storage elements 21 while sandwiching them in the X-axis direction. Note that at least one of the first holding member 23 and the second holding member 24 does not have to be bonded to the energy storage element 21. In other words, both first holding member 23 and second holding member 24 do not have to be joined to energy storage element 21.

[0036] The first holding member 23 and the second holding member 24 are formed from an insulating material such as polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene (PS), 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), polyethersulfone (PES), polyamide (PA), ABS resin, or a composite material thereof, or from a metal or the like with an insulating coating. As a result, the first holding member 23 and the second holding member 24 prevent the plurality of energy storage elements 21 from becoming electrically conductive with external conductive members such as metal members. However, if such conduction is not necessary, the first holding member 23 and the second holding member 24 may be formed from an electrically conductive member such as a metal. The first holding member 23 and the second holding member 24 may be made of the same material or different materials.

[0037] First holding member 23 includes a flat overlapping portion 25 that overlaps energy storage element 21 at the end in the negative X-axis direction, and bus bar support portion 26 that extends in the positive X-axis direction from overlapping portion 25. Bus bar support portion 26 extends in the positive X-axis direction from corners of overlapping portion 25 that are in the negative Y-axis and negative Z-axis directions, and supports a bus bar (not shown).

[0038] The second holding member 24 includes a board support portion 27 that overlaps the energy storage element 21 at its end in the positive direction of the X-axis. The board support portion 27 supports a circuit board 35 and includes a surrounding wall 29 that surrounds the circuit board 35. The board support portion 27 supports a bus bar and a fuse (not shown). At the end of the second holding member 24 in the negative direction of the Y-axis, a detection line holding member 28 extends in the negative direction of the X-axis. The second holding member 24 includes the detection line holding members 28 continuously. The detection line holding member 28 is a portion that holds a plurality of detection lines 36 connected to the circuit board 35 in order to detect the state (temperature, voltage, current, etc.) of each energy storage element 21.

[0039] [Energy storage element] Next, the energy storage elements 21 will be described in detail. Fig. 3 is a perspective view showing a plurality of energy storage elements 21 according to the embodiment separated from one another. The plurality of energy storage elements 21 have the same basic structure, but their outer shapes are partially different. Specifically, the odd-numbered energy storage elements 21 counted from the negative X-axis direction have partially different outer shapes from the even-numbered energy storage elements 21 counted from the negative X-axis direction. In other words, the odd-numbered energy storage elements 21 have the same outer shape, and the even-numbered energy storage elements 21 have the same outer shape.

[0040] First, a description will be given of the basic structure of the energy storage element 21. The energy storage element 21 includes an exterior film 210 and a pair of lead terminals 220 (positive and negative electrodes), and an electrode body 211 and an electrolyte (non-aqueous electrolyte: not shown) are housed inside the exterior film 210. There are no particular restrictions on the type of electrolyte as long as it does not impair the performance of the energy storage element 21, and any known material can be used as appropriate.

[0041] The exterior film 210 is a sheet-like exterior body made of laminate film, and houses the electrode assembly 211, an electrolyte solution, etc., sealed under reduced pressure. The exterior film 210 is configured by stacking two rectangular laminate films in the X-axis direction. The two laminate films are joined and sealed by heat welding, adhesive, etc., sandwiching a pair of lead terminals 220 between them. The two laminate films are joined and sealed by heat welding, adhesive, etc., at locations of the two laminate films that do not correspond to the pair of lead terminals 220. The laminate film is a flexible film made of multiple layers including a metal layer such as aluminum and a resin layer such as polypropylene (PP) or polyethylene (PE), and the resin layer is disposed at the joining location (sealed portion). The exterior film 210 may also be configured by forming a single laminate film into a bag shape and joining the ends of the laminate film together by heat welding, adhesive, etc.

[0042] The lead terminals 220 are conductive plate-like members (lead plates) electrically connected to the electrode body 211, and are arranged so as to penetrate the exterior film 210 and be exposed from the exterior film 210. The lead terminals 220 are an example of tab portions protruding from the edge of the energy storage element 21. In this embodiment, a pair of lead terminals 220 aligned in the Z-axis direction are arranged so as to protrude in the negative Y-axis direction from the edge of the exterior film 210 in the negative Y-axis direction. As described above, the edge of the exterior film 210 in the negative Y-axis direction is formed with seal portions 223 that join the edge and each lead terminal 220 by thermal welding, adhesive, or the like.

[0043] Here, the positive electrode lead terminal 220 is a lead terminal electrically connected to the positive electrode plate of the electrode body 211, and the negative electrode lead terminal 220 is a lead terminal electrically connected to the negative electrode plate of the electrode body 211. In other words, the lead terminals 220 are metal terminals for guiding electricity stored in the electrode body 211 to the external space of the energy storage element 21 and for introducing electricity into the internal space of the energy storage element 21 to store electricity in the electrode body 211. The positive electrode lead terminal 220 is made of aluminum, an aluminum alloy, or the like, and the negative electrode lead terminal 220 is made of copper, a copper alloy, or the like. In other words, the thermal conductivity of the negative electrode lead terminal 220 is higher than that of the positive electrode lead terminal 220. As long as the thermal conductivity of the negative electrode lead terminal 220 is higher than that of the positive electrode lead terminal 220, the material of each lead terminal 220 may be any material. The thermal conductivity of the positive electrode lead terminal 220 and the negative electrode lead terminal 220 can be measured in accordance with JIS R1611:2010.

[0044] The electrode body 211 is an electricity storage element (power generation element) formed by stacking a positive electrode plate, a negative electrode plate, and a separator. The positive electrode plate is a current collector foil made of a metal such as aluminum or an aluminum alloy, on which a positive electrode active material layer is formed. The negative electrode plate is a current collector foil made of a metal such as copper or a copper alloy, on which a negative electrode active material layer is formed. 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 is capable of absorbing and releasing charge transport ions. The separator can be a microporous sheet or nonwoven fabric made of resin. In this embodiment, the electrode body 211 is formed by stacking electrode plates (positive electrode plate and negative electrode plate) in the X-axis direction. The electrode body 211 may be an electrode body of any shape, such as a wound type electrode body formed by winding electrode plates (positive electrode plates and negative electrode plates), a laminated type (stack type) electrode body formed by stacking multiple flat electrode plates, or a bellows type electrode body in which electrode plates are folded in a bellows shape.

[0045] Next, the difference between odd-numbered storage elements 21 and even-numbered storage elements 21 will be described.

[0046] The odd-numbered energy storage elements 21 and the even-numbered energy storage elements 21 share a common configuration in that the exterior film 210 includes a main film 212 overlapping the electrode body 211 and a frame portion 213 protruding outward from the entire periphery of the main film 212. The main film 212 overlaps each side surface of the electrode body 211. The frame portion 213 is a sheet-like portion formed into a rectangular shape when viewed from the X-axis direction. A pair of lead terminals 220 protrude in the negative Y-axis direction from a first side 214 of the frame portion 213, which is the edge in the negative Y-axis direction, and are bent in the X-axis direction so as to be in opposite directions. Each lead terminal 220 is bent near the first side 214 of the exterior film 210. The portions of each lead terminal 220 farther from the main film 212 relative to the bending position are flat plate portions 231 and 232 formed into a flat plate shape.

[0047] Of the pair of lead terminals 220, one is a positive electrode lead terminal 221 and the other is a negative electrode lead terminal 222. A notch 235 is formed in a corner of a flat plate portion 231 of the positive electrode lead terminal 221 that is close to the center of the energy storage element 21 in the Z-axis direction. The flat plate portion 231 of the positive electrode lead terminal 221 protrudes in the negative X-axis direction, with its main surface facing the Y-axis direction. The flat plate portion 232 of the negative electrode lead terminal 222 protrudes in the positive X-axis direction, with its main surface facing the Y-axis direction.

[0048] Here, in the odd-numbered energy storage elements 21, the positive electrode lead terminal 221 is disposed in the positive direction of the Z axis, and the negative electrode lead terminal 222 is disposed in the negative direction of the Z axis. In contrast, in the even-numbered energy storage elements 21, the positive electrode lead terminal 221 is disposed in the negative direction of the Z axis, and the negative electrode lead terminal 222 is disposed in the positive direction of the Z axis.

[0049] The lead terminals 220 of each energy storage element 21 are joined to the lead terminals 220 or bus bars of the other energy storage elements 21. Specifically, the flat plate portion 231 of the positive electrode lead terminal 221 of the first energy storage element 21 is joined to a bus bar (not shown). The flat plate portions 232 and 231 of the negative electrode lead terminal 222 of the first energy storage element 21 and the positive electrode lead terminal 221 of the second energy storage element 21 are joined together. The flat plate portions 232 and 231 of the negative electrode lead terminal 222 of the second energy storage element 21 and the positive electrode lead terminal 221 of the third energy storage element 21 are joined together. The flat plate portions 232 and 231 of the negative electrode lead terminal 222 of the third energy storage element 21 and the positive electrode lead terminal 221 of the fourth energy storage element 21 are joined together. Negative electrode lead terminal 222 of fourth energy storage element 21 has flat plate portion 232 joined to another bus bar (not shown) by welding, adhesive, press-fitting, caulking, bolting, or the like.

[0050] [Detection Line] As shown in FIG. 2, five detection lines 36 are provided. Each detection line 36 is individually supported by a detection line holding member 28 of the second holding member 24. The detection line holding member 28 is formed with a plurality of walls 281 that separate each detection line 36. Each wall 281 protrudes from the main surface of the detection line holding member 28 in the negative Y-axis direction and extends in the X-axis direction. The multiple walls 281 are arranged at predetermined intervals in the Z-axis direction. Each wall 281 separates each detection line 36 individually.

[0051] Each detection wire 36 extends in the negative direction of the X axis from the substrate support portion 27 of the second holding member 24, and has a tip portion bent on the detection wire holding member 28 and joined to a bus bar or the lead terminal 220 of each energy storage element 21. Specifically, starting from the negative direction of the X axis, the tip portion of the first detection wire 36 protrudes from the detection wire holding member 28 in the positive direction of the Z axis and is joined to a bus bar connected to the positive lead terminal 221 of the first energy storage element 21. The tip portion of the second detection wire 36 protrudes from the detection wire holding member 28 in the negative direction of the Z axis and is joined to the negative lead terminal 222 of the second energy storage element 21. The tip portion of the third detection wire 36 protrudes from the detection wire holding member 28 in the positive direction of the Z axis and is joined to the negative lead terminal 222 of the third energy storage element 21. The tip of the fourth detection wire 36 protrudes from the detection wire holding member 28 in the negative direction of the Z axis and is joined to the negative electrode lead terminal 222 of the fourth storage element 21. The tip of the fifth detection wire 36 protrudes from the detection wire holding member 28 in the positive direction of the Z axis and is joined to a bus bar connected to the positive electrode lead terminal 221 of the fourth storage element 21.

[0052] Fig. 4 is a perspective view showing the joint structure between the detection wire 36 and the lead terminal 220 according to the embodiment. Fig. 4 shows the joint structure of the third detection wire 36. Here, the second energy storage element 21 is an example of a first energy storage element, and the exterior film 210, the electrode body 211 (see Fig. 3), and the negative electrode lead terminal 222 provided for the second energy storage element 21 are examples of a first exterior body, a first electrode body, and a first tab portion, respectively. In contrast, the third energy storage element 21 is an example of a second energy storage element, and the exterior film 210, the electrode body 211 (see Fig. 3), and the positive electrode lead terminal 221 provided for the third energy storage element 21 are examples of a second exterior body, a second electrode body, and a second tab portion, respectively.

[0053] As shown in FIG. 4 , the negative electrode lead terminal 222 of the second energy storage element 21 includes a bent portion 242, which is an example of a first bent portion, and a flat portion 232, which is an example of a first flat portion. The bent portion 242 is a portion that protrudes in the negative direction of the Y-axis from the first side 214 of the packaging film 210, and its tip portion is bent toward the third energy storage element 21. The flat portion 232 is continuous with the tip portion of the bent portion 242. The flat portion 232 protrudes in the positive direction of the X-axis, and its main surface faces the Y-axis direction. Specifically, the inner main surface of the flat portion 232 faces the positive direction of the Y-axis, and the outer main surface of the flat portion 232 faces the negative direction of the Y-axis.

[0054] The positive electrode lead terminal 221 of the third energy storage element 21 includes a bent portion 241, which is an example of a second bent portion, and a flat portion 231, which is an example of a second flat portion. The bent portion 241 is a portion that protrudes from the first side 214 of the exterior film 210 in the negative Y-axis direction, and its tip portion is bent toward the second energy storage element 21. The flat portion 231 is continuous with the tip portion of the bent portion 241. The flat portion 231 protrudes in the negative X-axis direction, and its main surface faces the Y-axis direction. Specifically, the inner main surface of the flat portion 231 faces the positive Y-axis direction, and the outer main surface of the flat portion 231 faces the negative Y-axis direction.

[0055] The flat plate portion 231 is joined to the flat plate portion 232 in the negative Y-axis direction. Specifically, the inner main surface of the flat plate portion 231 and the outer main surface of the flat plate portion 232 are joined to each other in an overlapping manner. The flat plate portions 231 and 232 are disposed generally parallel to the XZ plane. The notch 235 of the flat plate portion 231 is formed in a diagonal line extending from the positive X-axis direction to the negative Z-axis direction. The detection line 36 has a joint 361 joined to the flat plate portion 232 at a position corresponding to the notch 235. The joint 361 is a portion where the detection line 36 and the flat plate portion 232 are joined by thermal joining such as welding, soldering, or thermal caulking.

[0056] The detection wire 36 is formed in a shape that extends in the negative X-axis direction, passes through the joint portion 361, and is folded back to reach the joint portion 361. This provides an excess length for the detection wire 36. The folded-back point of the detection wire 36 is located further in the negative X-axis direction than the first edge 214 of the exterior film 210 of the second energy storage element 21. This allows the excess length of the detection wire 36 to be longer. A wall 281 is located between the main portion 362 of the detection wire 36, which is located closer to the base end than the folded-back point, and the joint portion 361. The wall 281 blocks heat generated when the detection wire 36 and the flat plate portion 232 are joined, thereby suppressing the thermal effect on the main portion 362.

[0057] Next, a detailed description will be given of the positional relationship between the joint 361 and the flat plate portion 232. Fig. 5 is a plan view showing the positional relationship between the joint 361 and the flat plate portion 232 according to the embodiment. In Fig. 5, portions of the detection line 36 other than the joint 361 are not shown.

[0058] 5, the joint portion 361 is disposed at a position facing the notch 235 of the flat plate portion 231, and is disposed at a position away from the notch 235. In other words, the positive electrode lead terminal 221, which is an example of a second tab portion, is shaped so as not to overlap the joint portion 361 when viewed from the Y-axis direction.

[0059] Here, the negative electrode lead terminal 222, which is an example of a first tab portion, protrudes by a protrusion length L10 from the first side 214 of the exterior film 210 as a base point (see FIG. 4). In FIG. 5, the center of the protrusion length L10 of the negative electrode lead terminal 222 is indicated by a first center line L1. The joint portion 361 is disposed at a position between the first center line L1 and the tip end of the negative electrode lead terminal 222. In other words, the length from the joint portion 361 to the seal portion 223 can be made longer compared to when the joint portion 361 is disposed in the negative X-axis direction relative to the first center line L1 (two-dot chain line Q in FIG. 5). This makes it difficult for heat generated when forming the joint portion 361 to be transmitted to the seal portion 223.

[0060] This joining structure is applicable to a portion where the lead terminals 220 of two adjacent energy storage elements 21 are joined together. That is, it is also applicable when a second detection wire 36 is joined to the negative electrode lead terminal 222 of the first energy storage element 21 and the positive electrode lead terminal 221 of the second energy storage element 21. It is also applicable when a fourth detection wire 36 is joined to the negative electrode lead terminal 222 of the third energy storage element 21 and the positive electrode lead terminal 221 of the fourth energy storage element 21.

[0061] [Effects, etc.] As described above, according to the present embodiment, the position between the center (first center line L1) of the protrusion length L10 of the negative electrode lead terminal 222 (first tab portion) of the second energy storage element 21 and the tip end of the negative electrode lead terminal 222 is a position away from the seal portion 223. Since the joint portion 361 of the detection wire 36 is joined to the negative electrode lead terminal 222 at this position, the heat transfer path to the seal portion 223 can be lengthened. Therefore, heat generated during joining is less likely to be transferred to the seal portion 223, and damage to the seal portion 223 can be suppressed.

[0062] Here, from the viewpoint of lengthening the heat transfer path, it is preferable that at least a portion of the joint 361 is disposed between the first center line L1 and the tip end of the flat plate portion 232. It is more preferable that the joint 361 does not overlap the first center line L1. It is even more preferable that at least a portion of the joint 361 is disposed between the tip end and the center (second center line L2) between the tip end of the flat plate portion 232 and the first center line L1. It is most preferable that the joint 361 does not overlap the second center line L2.

[0063] The positive electrode lead terminal 221 has a shape that does not overlap the joint portion 361 when viewed from the direction in which the negative electrode lead terminal 222 and the positive electrode lead terminal 221 overlap (the Y-axis direction), and therefore the positive electrode lead terminal 221 is unlikely to get in the way when joining the detection wire 36. This improves the workability of the joining operation.

[0064] The negative electrode lead terminal 222 of the second energy storage element 21 is bent toward the third energy storage element 21, and the positive electrode lead terminal 221 of the third energy storage element 21 is bent toward the second energy storage element 21. Therefore, the flat portion 232 of the negative electrode lead terminal 222 and the flat portion 231 of the positive electrode lead terminal 221 face in the Y-axis direction, which makes it possible to reduce the dimension of the energy storage device 1 in the Y-axis direction. In other words, even when the negative electrode lead terminal 222 and the positive electrode lead terminal 221 are bent, there are few restrictions on joining the joint portion 361 of the detection wire 36 to the negative electrode lead terminal 222 of the second energy storage element 21.

[0065] Since the joint portion 361 is disposed on the flat plate portion 232 of the negative electrode lead terminal 222, the detection wire 36 and the flat plate portion 232 can be joined on the negative Y-axis side. Therefore, the second and third storage elements 21 aligned in the X-axis direction can be stably joined without interfering with the joining operation.

[0066] When viewed from the X-axis direction, the flat plate portion 231 is disposed further outward in the Y-axis direction (negative Y-axis direction) than the flat plate portion 232, so that the amount of protrusion of the detection line 36 and the joint portion 361 in the negative Y-axis direction can be reduced. In other words, the dimension of the energy storage device 1 in the Y-axis direction can be further reduced.

[0067] The detection line 36 extends in the X-axis direction, passes through the joint 361, and then folds back to reach the joint 361. This results in an excess length of the detection line 36. Because the X-axis direction is the direction in which the second and third storage elements 21 are aligned, the lengths of the second and third storage elements 21 in the X-axis direction are likely to vary during manufacturing. Furthermore, the second and third storage elements 21 may expand in the X-axis direction during use. That is, the lengths of the second and third storage elements 21 in the X-axis direction may become larger or smaller than the set value during manufacturing or use. In particular, if the lengths of the second and third storage elements 21 in the X-axis direction become larger than the set value, the detection line 36 may be pulled in the X-axis direction, potentially damaging the joint 361. Therefore, by providing an excess length to the detection wire 36, it becomes easier to arrange the detection wire 36 during joining, and the workability of the joining work can be improved. Furthermore, even if the detection wire 36 is pulled, the excess length of the detection wire 36 deforms, so damage to the joint 361 can be suppressed.

[0068] Since the flat plate portion 231 has the notch 235 formed therein so as not to overlap the joint portion 361, the notch 235 can prevent the cross-sectional area of ​​the flat plate portion 231 from decreasing. Therefore, the resistance of the electricity storage device 1 can be prevented from increasing.

[0069] [Description of Modifications] The following describes various modifications of the above embodiment. In the following description, the same parts as those in the above embodiment or other modifications are designated by the same reference numerals, and the description thereof may be omitted.

[0070] (Variation 1) Fig. 6 is a plan view showing the flat plate portion 231a and the flat plate portion 232 according to Modification 1. Fig. 6 is a view corresponding to Fig. 5. As shown in Fig. 6, the flat plate portion 231a has a rectangular notch 235a at the middle of both ends in the Z-axis direction. The end of the notch 235a facing the positive X-axis direction is positioned further in the positive X-axis direction than the first center line L1. Within this notch 235a, a joint portion 361a is positioned further in the positive X-axis direction than the first center line L1, and is joined to the flat plate portion 232.

[0071] Modification 1 can achieve the same effects as the above-described embodiment. In particular, in Modification 1, since the joint portion 361a is disposed within the rectangular cutout 235a, by disposing the joint portion 361a between the first center line L1 and the edge of the cutout 235a in the positive X-axis direction, the joint portion 361a can be easily disposed at a position in the positive X-axis direction relative to the first center line L1.

[0072] (Variation 2) FIG. 7 is a plan view showing the flat plate portion 231b and the flat plate portion 232 according to Modification 2. FIG. 7 is a view corresponding to FIG. 5. As shown in FIG. 7, the flat plate portion 231b does not have a notch and is formed in a rectangular shape. The length of the flat plate portion 231b in the Z-axis direction is shorter than the length of the flat plate portion 232 in the Z-axis direction. Therefore, the flat plate portion 231b has a shape that does not overlap with the joint portion 361 when viewed from the Y-axis direction. Within the flat plate portion 232, the joint portion 361 is disposed in a position that is further in the negative Z-axis direction than the end of the flat plate portion 231b in the negative Z-axis direction and further in the positive X-axis direction than the first center line L1, and is joined to the flat plate portion 232.

[0073] According to Modification 2, it is possible to achieve the same effects as the above-described embodiment. In particular, in Modification 2, the flat plate portion 231b does not have a notch, and therefore, it is possible to achieve a simple structure.

[0074] (Variation 3) FIG. 8 is a plan view showing the flat plate portion 231c and the flat plate portion 232 according to Modification 3. FIG. 8 is a view corresponding to FIG. 5. As shown in FIG. 8, the flat plate portion 231c does not have a notch and is formed in a rectangular shape. The length of the flat plate portion 231c in the Z-axis direction is equal to the length of the flat plate portion 232 in the Z-axis direction. The flat plate portion 232 is superimposed on the main surface of the flat plate portion 231c in the negative Y-axis direction. In other words, the main surface of the flat plate portion 232 in the negative Y-axis direction is entirely exposed. A joint portion 361 is disposed within the main surface of the flat plate portion 232 in the negative Y-axis direction, at a position in the positive X-axis direction relative to the first center line L1, and is joined to the flat plate portion 232. In this way, the flat plate portion 231c may have a shape that overlaps the joint portion 361 when viewed in the Y-axis direction.

[0075] According to Modification 3, it is possible to achieve the same effects as the above-described embodiment. In particular, in Modification 3, the flat plate portion 231c does not have a notch, and therefore, it is possible to achieve a simple structure.

[0076] (Variation 4) In the above embodiment, the case where the center (first center line L1) of the protruding length L10 of the negative electrode lead terminal 222 is contained within the flat plate portion 232 has been exemplified. In this fourth modification, a case where the center of the protruding length of the negative electrode lead terminal is not contained within the flat plate portion will be described.

[0077] FIG. 9 is a side view showing a negative electrode lead terminal 222d and a positive electrode lead terminal 221d according to Modification 4. In FIG. 9, the negative electrode lead terminal 222d is indicated by a dashed line. As shown in FIG. 9, the flat plate portion 232d of the negative electrode lead terminal 222d and the flat plate portion 231d of the positive electrode lead terminal 221d are disposed further in the negative Y-axis direction than in the above embodiment. In this case, the center L4d of the protruding length L10d of the negative electrode lead terminal 222d is disposed outside the flat plate portion 232d of the negative electrode lead terminal 222d. Even in this case, it is sufficient that the joint portion 361d is disposed between the center L4d of the protruding length L10d of the negative electrode lead terminal 222d and the tip end of the negative electrode lead terminal 222d. In other words, as shown in FIG. 9, the joint portion 361d may be disposed at a position other than the flat plate portion 232d. As described above, even with the structure of Modification 4, the same effects as those of the above embodiment can be achieved.

[0078] (Variation 5) In the above embodiment, the positive electrode lead terminal 221 and the negative electrode lead terminal 222 are joined in a bent state. In this modification 5, a case where the positive electrode lead terminal and the negative electrode lead terminal are not bent will be described.

[0079] FIG. 10 is a side view showing a negative electrode lead terminal 222e and a positive electrode lead terminal 221e according to Modification 5. In FIG. 10, the negative electrode lead terminal 222e is indicated by a dashed line. As shown in FIG. 10, the negative electrode lead terminal 222e and the positive electrode lead terminal 221e are smoothly curved, and their tip ends are joined together. It can be said that the negative electrode lead terminal 222e and the positive electrode lead terminal 221e each extend generally along the Y-axis direction. In this manner, the negative electrode lead terminal 222e does not necessarily have to include a first bent portion or a first flat portion, and the positive electrode lead terminal 221e does not necessarily have to include a second bent portion or a second flat portion. Even in this case, the joint portion 361e is located between the center L4e of the protrusion length L10e of the negative electrode lead terminal 222e and the tip end of the negative electrode lead terminal 222e. As a result, the structure of Modification 5 can achieve the same effects as those of the above-described embodiment.

[0080] (others) Although the energy storage device 1 according to the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. In other words, the embodiment disclosed herein is illustrative in all respects and is not restrictive, and the scope of the present invention includes all modifications within the meaning and scope of the claims.

[0081] In the above embodiment, the exterior film 210 has a rectangular shape when viewed from the X-axis direction, but the exterior film 210 may have any shape. Other shapes of the exterior film 210 include polygonal shapes other than rectangular, oval shapes, elliptical shapes, and circles.

[0082] In the above embodiment, an example is shown in which the detection line 36 is folded back in a U-shape, but the detection line 36 may be folded back in any manner, or may be joined to the negative electrode lead terminal 222 without being folded back.

[0083] In the above embodiment, an example is given of a pair of lead terminals 220 protruding from the first side 214 of the exterior film 210, but one of the pair of lead terminals 220 may protrude from the first side 214 of the exterior film 210, and the other lead terminal 220 may protrude from a side other than the first side 214 of the exterior film 210.

[0084] Any combination of the components included in the embodiments and their modifications is also included within the scope of the present invention. [Industrial Applicability]

[0085] The present invention can be applied to an electricity storage device or the like that includes an electricity storage element such as a lithium ion secondary battery. [Explanation of symbols]

[0086] 1. Energy storage device 10. Exterior body 20 Energy storage unit 21 Storage element (first storage element, second storage element) 22 Retaining member 23 First retaining member 24 Second holding member 25 Superimposed section 26 Busbar support 36 Detection line 210 Exterior film (first exterior body, second exterior body) 211 Electrode body (first electrode body, second electrode body) 212 Main body film 213 Frame 214 First Side 220 Lead terminal 221, 221d, 221e Positive electrode lead terminal (second tab portion) 222, 222d, 222e Negative electrode lead terminal (first tab portion) 223 Seal part 231, 231a, 231b, 231c flat plate part (second flat plate part) 232, 232d flat plate part (first flat plate part) 235, 235a notch 241 Bending section (second bending section) 242 Bending section (first bending section) 281 Wall 361, 361a, 361d, 361e joints 362 Main part L1 First center line L2 Second center line L4d, L4e center L10, L10d, L10e protrusion length Q Two-dot chain line

Claims

1. a first storage element and a second storage element arranged in a first direction; a detection line for detecting a state of the first storage element and the second storage element, The first storage element is a first exterior body; a first tab portion protruding from an edge portion of the first exterior body, the second storage element includes a second tab portion overlapping and connected to the first tab portion, the edge portion of the first exterior body includes a seal portion that seals the edge portion and the first tab portion; the detection line includes a joining portion joined to the first tab portion at a position between the center of the protruding length of the first tab portion and the tip end of the first tab portion; The thermal conductivity of the first tab portion is higher than the thermal conductivity of the second tab portion. Energy storage device.

2. the second tab portion has a shape that does not overlap the joint portion when viewed from a direction in which the first tab portion and the second tab portion overlap; The power storage device according to claim 1 .

3. The first tab portion is a first bent portion bent toward the second energy storage element; a first flat plate portion facing a second direction intersecting the first direction, The second tab portion is a second bent portion bent toward the first energy storage element; a second flat plate portion facing the second direction, The electricity storage device according to claim 1 or 2.

4. The joint portion is disposed on the first flat plate portion. The power storage device according to claim 3 .

5. The second flat plate portion is disposed outward in the second direction from the first flat plate portion when viewed from the first direction. The power storage device according to claim 3 .

6. the detection line extends in the first direction, passes through the joint, and is folded back at a position where it reaches the joint; The electricity storage device according to claim 1 or 2.

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