Energy storage device

Abstract

This invention provides an energy storage device that can effectively utilize the space between the positive electrode and the negative electrode. [Solution] The energy storage device comprises a first energy storage element and a second energy storage element arranged in a first direction, and a busbar electrically connected to the first energy storage element and the second energy storage element. The first energy storage element comprises a first casing and a pair of first lead terminals that protrude from one edge of the first casing in a second direction intersecting the first direction and are arranged in a third direction intersecting the first and second directions. The second energy storage element comprises a second casing and a pair of second lead terminals that protrude from one edge of the second casing in a second direction and are arranged in a third direction. The busbar extends along the first direction, positioned between the pair of first lead terminals and between the pair of second lead terminals.

Description

Technical Field

[0001] The present invention relates to a power storage device.

Background Art

[0002] Patent Document 1 discloses a cell assembly in which a plurality of capacitor cells are stacked. At one end of each capacitor cell, a positive electrode current collector and a negative electrode current collector protrude.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, since there is a possibility that an excess space will occur between the positive electrode current collector and the negative electrode current collector, it is required to effectively utilize the space.

[0005] The present invention has been made by the inventors of the present application newly paying attention to the above problems, and an object thereof is to provide a power storage device capable of effectively utilizing the space between the positive electrode current collector and the negative electrode current collector.

Means for Solving the Problems

[0006] An energy storage device according to one aspect of the present invention comprises a first energy storage element and a second energy storage element arranged in a first direction, and a busbar electrically connected to the first energy storage element and the second energy storage element, wherein the first energy storage element comprises a first outer casing and a pair of first lead terminals that protrude from one edge of the first outer casing in a second direction intersecting the first direction and are arranged in a third direction intersecting the first and second directions, the second energy storage element comprises a second outer casing and a pair of second lead terminals that protrude from one edge of the second outer casing in the second direction and are arranged in the third direction, and the busbar extends along the first direction while being positioned between the pair of first lead terminals and between the pair of second lead terminals. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an energy storage device that can effectively utilize surplus space. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a perspective view showing the external appearance of an energy storage device according to an embodiment. [Figure 2] Figure 2 is an exploded perspective view showing the components of the energy storage device according to the embodiment when it is disassembled. [Figure 3] Figure 3 is a perspective view showing a part of the busbar according to the embodiment. [Figure 4] Figure 4 is a perspective view showing each of the multiple energy storage elements according to the embodiment separately. [Figure 5] Figure 5 is a plan view showing the positive lead terminal and negative lead terminal according to the embodiment before they are bent. [Figure 6] Figure 6 is a plan view of the energy storage unit according to the embodiment, viewed from the negative Y-axis direction. [Figure 7A] Figure 7A is an explanatory diagram showing the first lead terminal and the second lead terminal according to the modified example 1. [Figure 7B] Figure 7B is an explanatory diagram showing the first and second lead terminals according to the modified example 1. [Modes for carrying out the invention]

[0009] (1) An energy storage device according to one aspect of the present invention comprises a first energy storage element and a second energy storage element arranged in a first direction, and a busbar electrically connected to the first energy storage element and the second energy storage element, wherein the first energy storage element comprises a first outer casing and a pair of first lead terminals that protrude from one edge of the first outer casing in a second direction intersecting the first direction and are arranged in a third direction intersecting the first and second directions, the second energy storage element comprises a second outer casing and a pair of second lead terminals that protrude from one edge of the second outer casing in a second direction and are arranged in a third direction, and the busbar extends along the first direction while being positioned between the pair of first lead terminals and between the pair of second lead terminals.

[0010] According to the energy storage device described in (1) above, busbars extending in the first direction are arranged between a pair of first lead terminals and between a pair of second lead terminals, which may be surplus space. Therefore, the space between the pair of first lead terminals and between the pair of second lead terminals can be effectively utilized.

[0011] (2) In the energy storage device described in (1) above, a detection line may be provided for detecting the state of the first energy storage element and the second energy storage element, and the detection line may be supported by the busbar.

[0012] According to the energy storage device described in (2) above, the detection wire is supported by busbars positioned between a pair of first lead terminals and between a pair of second lead terminals, so no additional members are required to support the detection wire.

[0013] (3) In the power storage device according to (2) above, among the pair of the first lead terminals, one of the first lead terminals includes a first base portion and a first tip portion continuous with the first base portion. Among the pair of the second lead terminals, the second lead terminal corresponding to the one first lead terminal includes a second base portion and a second tip portion continuous with the second base portion. The first tip portion includes a joint portion joined to the second tip portion and a protruding portion protruding in a direction intersecting the first direction from the second tip portion. The detection line may be joined to the protruding portion.

[0014] According to the power storage device described in (3) above, in the first tip portion of the first lead terminal, a joint portion joined to the second tip portion of the second lead terminal and a protruding portion protruding from the joint portion are provided. In the case of a form without a protruding portion, a notch is provided in the joint portion and the detection line is joined in the notch. In this case, since the joint portion becomes small, the electrical resistance increases. In order to suppress the increase in resistance, if the notch is made small, it becomes difficult to easily join the detection line. On the other hand, in this embodiment, since the detection line is joined to the protruding portion, the joining area of the detection line can be secured without making the joint portion small. Therefore, the detection line can be easily joined while suppressing the increase in the resistance of the joint portion.

[0015] (4) In the power storage device according to any one of (1) to (3) above, the area of the surface of the bus bar facing the third direction may be smaller than the area of the surface of the bus bar facing the second direction.

[0016] According to the power storage device described in (4) above, since the area of the surface of the bus bar facing the third direction is smaller than the area of the surface of the bus bar facing the second direction, heat from the bus bar is less likely to be transmitted to the first lead terminal and the second lead terminal. Therefore, an increase in the electrical resistance due to a temperature rise of the first lead terminal and the second lead terminal can be suppressed, and an increase in the electrical resistance of the power storage element can be suppressed.

[0017] (Embodiment) The following description of an energy storage device according to an embodiment (including its modifications) of the present invention will be given with reference to the drawings. The embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement positions of components, and connection configurations shown in the following embodiments are examples and are not intended to limit the present invention. Dimensions, etc., are not strictly illustrated in each figure. In each figure, the same or similar components are denoted by the same reference numeral. The names of each component (each component) in this embodiment are those of this embodiment and may differ from the names of each component (each component) in the background art.

[0018] In the following description and drawings, the direction in which the main body and cover of the casing of the energy storage device are aligned, or the direction in which the multiple energy storage elements provided in the energy storage device are aligned, is defined as the X-axis direction. The direction in which each lead terminal of the energy storage element protrudes is defined as the Y-axis direction. The direction in which a pair of lead terminals provided in the energy storage element are aligned, or the vertical direction, is defined as the Z-axis direction. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in the following embodiments and their modifications). The X-axis direction is an example of a first direction, the Y-axis direction is an example of a second direction, and the Z-axis direction is an example of a third direction. Depending on the usage, the Z-axis direction may not be vertical, but for the sake of explanation, the Z-axis direction will be described as vertical in the following description. In the following description, the X-axis positive direction refers to the direction of the arrow on the X-axis, and the X-axis negative direction refers to the opposite side from the X-axis positive direction. The same applies to the Y-axis and Z-axis directions. Furthermore, expressions indicating relative directions or orientations, such as parallel and orthogonal, include cases where they are not strictly those directions or orientations. When two directions are orthogonal, it means not only that the two directions are perfectly orthogonal, but also that they are substantially orthogonal, that is, that they contain a difference of a few percent. In the following explanation, when we use the term "insulation," we mean "electrical insulation." Insulating materials have a volume resistivity of 1 × 10⁻⁶. 6 Ωm or greater, more preferably 1 × 10⁻⁶ 7 Ωm or greater, more preferably 1 × 10⁻⁶ 10It is preferably formed from a material of Ωm or more.

[0019] [General description of the power storage device] First, a general description of the power storage device 1 according to the embodiment will be given with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing the appearance of the power storage device 1 according to the embodiment. FIG. 2 is an exploded perspective view showing each component when the power storage device 1 according to the embodiment is disassembled.

[0020] The power storage device 1 is a device that can charge electricity from the outside and discharge electricity to the outside. In this embodiment, it has a rectangular parallelepiped shape. A rectangular parallelepiped is a hexahedron in which all faces are composed of rectangles or squares. The power storage device 1 is a battery module (battery pack) used for power storage applications or power supply applications, etc. Specifically, the power storage device 1 is used for driving or engine starting of moving bodies such as automobiles, motorcycles, watercraft, ships, snowmobiles, agricultural machinery, construction machinery, automatic guided vehicles (AGV: Automatic Guided Vehicle), or railway vehicles for electric railways. Examples of the above-mentioned automobiles include electric vehicles (EV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), and fossil fuel (gasoline, light oil, liquefied natural gas, etc.) vehicles. Examples of the above-mentioned railway vehicles for electric railways include trains, monorails, linear motor cars, and hybrid trains equipped with both a diesel engine and an electric motor. The power storage device 1 may be used for stationary batteries used for household or business use, etc.

[0021] As shown in FIGS. 1 and 2, the power storage device 1 includes a power storage unit 20 and an exterior body 10 that houses the power storage unit 20. The exterior body 10 includes an exterior body main body 11 that houses the power storage unit 20 and an exterior body lid 12 that closes the exterior body main body 11.

[0022] The outer casing 10 is a rectangular (box-shaped) container (module case) that constitutes the outer casing of the energy storage device 1. In other words, the outer casing 10 is a component that fixes the energy storage unit 20 and other components in a predetermined position and protects these components from impacts and other damage.

[0023] The outer casing body 11 is a bottomed rectangular cylindrical member with an open end in the X-axis positive direction, and its open portion is an opening 111. The opening 111 is rectangular in shape when viewed from above (in the X-axis direction). Inside the opening 111 of the outer casing body 11, in addition to the energy storage unit 20, a plurality of busbars (not shown) and fuses (not shown) held by the energy storage unit 20 are housed.

[0024] The outer casing cover 12 is a member that closes the opening 111 of the outer casing body 11, and is joined to the outer casing body 11 in a state where the opening 111 of the outer casing body 11 is closed from the X-axis positive direction. A circuit board 35 is positioned outside the opening 111 at a location corresponding to the outer casing cover 12. In other words, the circuit board 35 is housed between the outer casing body 11 and the outer casing cover 12. The outer casing cover 12 is equipped with a pair (positive and negative) of external terminals 81. The external terminals 81 are electrically connected to a plurality of energy storage elements 21 included in the energy storage unit 20 via each busbar, fuse, 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 material made of metal such as copper, copper alloy, aluminum, aluminum alloy, nickel, or a combination thereof, or a conductive material other than metal.

[0025] Here, each busbar is a plate-shaped member that electrically connects the external terminal 81 and the energy storage element 21. Each busbar is formed from a conductive material made of metal such as copper, copper alloy, aluminum, aluminum alloy, or nickel, or a combination thereof, or from a conductive material other than metal.

[0026] A fuse is a component that protects the circuit board 35 and multiple energy storage elements 21, etc., from high currents exceeding the rated value. When a current exceeding the rated value flows through the fuse, the fuse melts, thereby interrupting the flow of current.

[0027] The circuit board 35 is equipped with multiple electrical components (not shown), and these multiple electrical components form a detection circuit for detecting the state (temperature, voltage, current, etc.) of each energy storage element 21, as well as a control circuit for controlling charging and discharging.

[0028] The outer casing body 11 and outer casing cover 12 of the outer casing 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), polyetheretherketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polyamide (PA), ABS resin, or composite materials thereof, or from metal with an insulating coating. The outer casing 10 thereby prevents the energy storage element 21, etc. from coming into contact with external metal components. The outer casing 10 may be formed from a conductive material such as metal, as long as the electrical insulation of the energy storage element 21, etc. is maintained. The outer casing body 11 and the outer casing cover 12 may be made of the same material or of different materials.

[0029] [Energy storage unit] The energy storage unit 20 comprises a plurality of energy storage elements 21 and a holding member 22.

[0030] 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 in line along the X-axis. The plurality of energy storage elements 21 are arranged in a position where their main surfaces face each other. The size and shape of the energy storage element 21 are not limited as long as it is a pouch-type energy storage element. 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 fixed electrolyte. The energy storage element 21 may be a primary battery instead of a secondary battery. Multiple energy storage elements 21 are arranged in the X-axis direction, and adjacent energy storage elements 21 may or may not be joined together by adhesive or double-sided tape. Details of the energy storage elements 21 will be described later.

[0031] The holding member 22 is a member that holds a plurality of energy storage elements 21. The holding member 22 comprises a first holding member 23 and a second holding member 24 that holds the plurality of 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 plurality of energy storage elements 21 and is joined to the energy storage elements 21 located at the ends in the negative X-axis direction of the plurality of energy storage elements 21 by adhesive or double-sided tape. The second holding member 24 is arranged in the positive X-axis direction of the plurality of energy storage elements 21 and is joined to the energy storage elements 21 located at the ends in the positive X-axis direction of the plurality of energy storage elements 21 by adhesive or double-sided tape. As a result, the first holding member 23 and the second holding member 24 hold the plurality of energy storage elements 21 by sandwiching them in the X-axis direction. At least one of the first holding member 23 and the second holding member 24 does not have to be joined to the energy storage elements 21. In other words, both the first holding member 23 and the second holding member 24 do not have to be joined to the energy storage elements 21.

[0032] The first retaining member 23 and the second retaining member 24 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), polyetheretherketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), polyamide (PA), ABS resin, or composite materials thereof, or from metal with an insulating coating. As a result, the first retaining member 23 and the second retaining member 24 suppress electrical contact between the multiple energy storage elements 21 and conductive materials such as external metal members. However, if such contact is not necessary, the first retaining member 23 and the second retaining member 24 may be formed from conductive materials such as metal. The first retaining member 23 and the second retaining member 24 may be made of the same material or of different materials.

[0033] The first holding member 23 is a flat plate-shaped member that overlaps the energy storage element 21 at the end in the negative X-axis direction.

[0034] The second retaining member 24 includes a substrate support portion 27 that overlaps the energy storage element 21 at its end in the positive X-axis direction, and an annular enclosure wall 29 that protrudes from the substrate support portion 27 in the positive X-axis direction. The substrate support portion 27 supports the circuit board 35, and this circuit board 35 is surrounded by the enclosure wall 29. The substrate support portion 27 supports a plurality of busbars and fuses. At the end of the second retaining member 24 in the negative Y-axis direction, one of the plurality of busbars, a busbar 28, extends in the negative X-axis direction from the central part in the Z-axis direction. The busbar 28 is L-shaped when viewed in the Y-axis direction.

[0035] Figure 3 is a perspective view showing a part of a busbar 28 according to an embodiment. As shown in Figure 3, the busbar 28 is a flat conductive member with its thickness direction oriented along the Y-axis. Therefore, the area of ​​the first busbar surface 28a facing the negative Z-axis direction is smaller than the area of ​​the second busbar surface 28b facing the negative Y-axis direction. In other words, the projected area of ​​the busbar 28 viewed from the Z-axis direction is smaller than the projected area of ​​the busbar 28 viewed from the Y-axis direction.

[0036] The busbar 28 comprises a long side portion 281 extending in the negative X-axis direction from the second holding member 24, and a short side portion 282 extending in the positive Z-axis direction from the X-axis negative end of the long side portion 281. The long side portion 281 is the part 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. The short side portion 282 is the part that is electrically connected to the positive lead terminal 221 (see Figure 4) provided on the energy storage element 21 at the X-axis negative end.

[0037] [Energy storage element] Next, the details of the energy storage elements 21 will be described. Figure 4 is a perspective view showing each of the multiple energy storage elements 21 according to the embodiment separately. Although the multiple energy storage elements 21 have similar basic structures, their external shapes differ in some respects. Specifically, the external shapes of the odd-numbered energy storage elements 21 and the even-numbered energy storage elements 21 differ in some respects, starting from the negative X-axis direction. In other words, the external shapes of the odd-numbered energy storage elements 21 are identical, and the external shapes of the even-numbered energy storage elements 21 are identical.

[0038] First, the basic structure of the energy storage element 21 will be described. The energy storage element 21 comprises an outer film 210 and a pair of lead terminals 220 (positive and negative electrodes). Inside the outer film 210 are an electrode body 211 and an electrolyte (non-aqueous electrolyte: not shown). As for the electrolyte, there are no particular restrictions on its type as long as it does not impair the performance of the energy storage element 21, and any known material can be used as appropriate.

[0039] The outer film 210 is a sheet-like outer casing made of laminate film, which contains the electrode body 211 and electrolyte solution sealed inside under reduced pressure. The outer film 210 is composed of two rectangular laminate films overlapping in the X-axis direction. The two laminate films are joined and sealed by heat welding or adhesive, sandwiching a pair of lead terminals 220. In areas of the two laminate films that do not correspond to the pair of lead terminals 220, the two laminate films are joined and sealed together by heat welding or adhesive. The laminate film is a flexible film consisting of multiple layers, including a metal layer such as aluminum and a resin layer such as polypropylene (PP) or polyethylene (PE), with the resin layer positioned at the joining points (sealed areas). The outer film 210 may also be constructed by forming a single laminate film into a bag shape and joining the ends of the laminate films together by heat welding or adhesive.

[0040] The lead terminals 220 are conductive plate-shaped members (lead plates) electrically connected to the electrode body 211, and are positioned exposed from the outer film 210, penetrating through it. 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 positioned protruding in the Y-axis negative direction from the Y-axis negative edge of the outer film 210. As described above, a seal portion 223 is formed on the Y-axis negative edge of the outer film 210, joining the edge and each lead terminal 220 by heat welding or adhesive.

[0041] Here, the positive lead terminal 220 is a lead terminal electrically connected to the positive electrode plate of the electrode body 211, and the negative lead terminal 220 is a lead terminal electrically connected to the negative electrode plate of the electrode body 211. In other words, the lead terminal 220 is a metal terminal that guides the electricity stored in the electrode body 211 to the external space of the energy storage element 21, and also introduces electricity into the internal space of the energy storage element 21 in order to store electricity in the electrode body 211. The positive lead terminal 220 is made of aluminum, an aluminum alloy, etc., and the negative lead terminal 220 is made of copper, a copper alloy, etc.

[0042] The electrode body 211 is an energy storage element (power generation element) formed by laminating 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, with a positive electrode active material layer formed on top. The negative electrode plate is a current collector foil made of a metal such as copper or a copper alloy, with a negative electrode active material layer formed on top. As for 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 intercepting 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 laminating electrode plates (positive electrode plate and negative electrode plate) in the X-axis direction. The electrode body 211 may be any form of electrode body, such as a wound electrode body formed by winding electrode plates (positive electrode plate and negative electrode plate), a stacked electrode body formed by stacking multiple flat electrode plates, or a bellows-type electrode body in which electrode plates are folded in a bellows-like manner.

[0043] Next, we will explain the difference between the odd-numbered energy storage elements 21 and the even-numbered energy storage elements 21.

[0044] As a common configuration for odd-numbered and even-numbered energy storage elements 21, the outer film 210 comprises a main film 212 that overlaps the electrode body 211 and a frame portion 213 that protrudes outward from the entire periphery of the main film 212. The main film 212 overlaps each side of the electrode body 211. The frame portion 213 is a sheet-like portion and is formed in a rectangular shape when viewed from the X-axis direction. From the first side 214 of the frame portion 213, which is the edge in the negative Y-axis direction, a pair of lead terminals 220 protrude in the negative Y-axis direction and are bent in the X-axis direction so that they are in opposite directions. Each lead terminal 220 is bent near the first side 214 of the outer film 210. Of the pair of lead terminals 220, one is the positive electrode lead terminal 221 and the other is the negative electrode lead terminal 222.

[0045] In this configuration, for odd-numbered energy storage elements 21, the positive lead terminal 221 is positioned in the positive Z-axis direction, and the negative lead terminal 222 is positioned in the negative Z-axis direction. In contrast, for even-numbered energy storage elements 21, the positive lead terminal 221 is positioned in the negative Z-axis direction, and the negative lead terminal 222 is positioned in the positive Z-axis direction.

[0046] Figure 5 is a plan view showing the positive lead terminal 221 and negative lead terminal 222 of the embodiment before they are bent. Figure 5 shows the positive lead terminal 221 and negative lead terminal 222 provided on the first energy storage element 21.

[0047] In its pre-bending state, the positive lead terminal 221 is rectangular in plan view and protrudes from the first side 214 of the frame portion 213 in the negative Y-axis direction. The positive lead terminal 221 comprises a base portion 221a and a tip portion 221b continuous with the base portion 221a, which are aligned in the Y-axis direction. In Figure 5, the boundary between the base portion 221a and the tip portion 221b is shown by a dashed line V1. The base portion 221a is closer to the frame portion 213 than the tip portion 221b.

[0048] In its pre-bending state, the negative lead terminal 222 is L-shaped in plan view and protrudes from the first side 214 of the frame portion 213 in the negative Y-axis direction. The negative lead terminal 222 comprises a base portion 222a and a tip portion 222b continuous with the base portion 222a, which are aligned in the Y-axis direction. In Figure 5, the boundary between the base portion 222a and the tip portion 222b is shown by a dashed line V2. The base portion 222a is closer to the frame portion 213 than the tip portion 222b. The tip portion 222b protrudes from the base portion 222a in the negative Z-axis direction. Thus, in the Z-axis direction, the length L1 of the tip portion 222b is longer than the length L2 of the base portion 222a.

[0049] As shown in Figure 4, the positive lead terminal 221 protrudes in the negative X-axis direction due to the bending of the base portion 221a near the root. As a result, the tip portion 221b of the positive lead terminal 221 is positioned so that its main surface faces the Y-axis direction. On the other hand, the negative lead terminal 222 protrudes in the positive X-axis direction due to the bending of the base portion 222a near the root. As a result, the tip portion 222b of the negative lead terminal 222 is positioned so that its main surface faces the Y-axis direction.

[0050] Figure 6 is a plan view of the energy storage unit 20 according to the embodiment, viewed from the negative Y-axis direction. As shown in Figure 6, the lead terminals 220 of each energy storage element 21 are connected to the lead terminals 220 of other energy storage elements 21 or to the busbar 28. Specifically, the tip portion 221b of the positive lead terminal 221 of the first energy storage element 21 is connected to the short side portion 282 of the busbar 28. The tip portions 221b and 222b of the negative lead terminal 222 of the first energy storage element 21 and the tip portions 221b and 221b of the positive lead terminal 221 of the second energy storage element 21 are connected to each other. The tip portions 222b and 221b of the negative lead terminal 222 of the second energy storage element 21 and the tip portions 222b and 221b of the positive lead terminal 221 of the third energy storage element 21 are connected to each other. The negative lead terminal 222 of the third energy storage element 21 and the positive lead terminal 221 of the fourth energy storage element 21 are joined at their tips 221b and 222b. The negative lead terminal 222 of the fourth energy storage element 21 is joined at its tip 222b to another busbar (not shown). The joining method may be welding, bonding, press-fitting, crimping, or bolting.

[0051] Here, at the joint between the tip portion 221b and the tip portion 222b, a part of the tip portion 222b protrudes from the tip portion 221b. For this reason, the tip portion 222b can be said to have a joint portion 222c that is joined to the tip portion 221b and a protruding portion 222d that protrudes from the tip portion 221b in the Z-axis direction. The protruding portion 222d of each energy storage element 21 protrudes from the tip portion 221b in a direction away from the center in the Z-axis direction of each energy storage element 21.

[0052] Here, the first energy storage element 21 is considered an example of a first energy storage element, and the second energy storage element 21 is considered an example of a second energy storage element. In this case, the outer film 210 and the pair of lead terminals 220 of the first energy storage element 21 are examples of a first outer casing and a pair of first lead terminals, respectively. On the other hand, the outer film 210 and the pair of lead terminals 220 of the second energy storage element 21 are examples of a second outer casing and a pair of second lead terminals, respectively.

[0053] Similarly, the second energy storage element 21 is considered an example of the first energy storage element, and the third energy storage element 21 is considered an example of the second energy storage element. In this case, the outer film 210 and the pair of lead terminals 220 of the second energy storage element 21 are examples of the first outer casing and the pair of first lead terminals, respectively. On the other hand, the outer film 210 and the pair of lead terminals 220 of the third energy storage element 21 are examples of the second outer casing and the pair of second lead terminals, respectively.

[0054] Furthermore, the third energy storage element 21 is considered an example of the first energy storage element, and the fourth energy storage element 21 is considered an example of the second energy storage element. In this case, the outer film 210 and the pair of lead terminals 220 of the third energy storage element 21 are examples of the first outer casing and the pair of first lead terminals, respectively. On the other hand, the outer film 210 and the pair of lead terminals 220 of the fourth energy storage element 21 are examples of the second outer casing and the pair of second lead terminals, respectively.

[0055] In either case, the busbar 28 is positioned between the pair of first lead terminals and between the pair of second lead terminals.

[0056] [Detection line] There are four detection wires 36. Each detection wire 36 is supported by the long side portion 281 of the busbar 28. Each detection wire 36 may be fixed to the long side portion 281 by adhesive, welding, mechanical fixing structure, etc.

[0057] Each detection wire 36 extends in the negative X-axis direction from the substrate support portion 27 of the second holding member 24, is bent on the long side portion 281, and is joined to the short side portion 282 or the protruding portion 222d of each energy storage element 21.

[0058] Specifically, starting from the positive Z-axis direction, the first detection wire 36 is bent in the positive Z-axis direction from its long side portion 281, and then further bent in the negative X-axis direction. The first detection wire 36 is positioned to bypass the positive lead terminal 221 of the third energy storage element 21 from the positive X-axis direction. The tip of the first detection wire 36 is joined to the protruding portion 222d of the second energy storage element 21.

[0059] The second detection wire 36 is bent in the positive Z-axis direction from the long side portion 281, and then further bent in the negative X-axis direction. The second detection wire 36 is positioned to bypass the positive lead terminal 221 of the first energy storage element 21 from the positive X-axis direction. The tip of the second detection wire 36 is joined to the short side portion 282 of the busbar 28 at a position in the positive Z-axis direction relative to the positive lead terminal 221.

[0060] The third detection wire 36 is bent in the negative Z-axis direction from its long side portion 281, and then further bent in the positive X-axis direction. The third detection wire 36 is positioned to bypass the positive lead terminal 221 of the second energy storage element 21 from the negative X-axis direction. The tip of the third detection wire 36 is joined to the protrusion 222d of the first energy storage element 21.

[0061] The fourth detection wire 36 is bent in the negative Z-axis direction from its long side 281, and then further bent in the positive X-axis direction. The fourth detection wire 36 is positioned to bypass the positive lead terminal 221 of the fourth energy storage element 21 from the negative X-axis direction. The tip of the fourth detection wire 36 is joined to the protrusion 222d of the third energy storage element 21.

[0062] Thus, the joining targets (protruding portion 222d and short side portion 282) at the tip of the detection wire 36 protrude in the Z-axis direction from the tip portion 221b of the positive lead terminal 221. Therefore, even without making a notch in the tip portion 221b to reduce its size, sufficient area (joining area) for joining the detection wire 36 can be secured.

[0063] Here, when welding the tip of the detection wire 36 to the object to be joined, the welding is performed after sandwiching the object to be joined and the tip of the detection wire 36 between the welding fixture (horn and anvil). In other words, before welding, it is necessary to move the welding fixture to a welding position that sandwiches the object to be joined and the tip of the detection wire 36. If this movement distance is too long, the possibility of damage to the welding fixture increases. This is particularly noticeable in ultrasonic welding.

[0064] In this embodiment, the welding position is located outside the positive lead terminal 221. In other words, since the welding position is located close to the outer edge of each energy storage element 21, the travel distance of the welding jig can be reduced, and damage to the welding jig can be suppressed.

[0065] [Effects, etc.] As described above, according to this embodiment, a busbar 28 extending in the X-axis direction is positioned between the pair of lead terminals 220 provided on each energy storage element 21, which may otherwise be surplus space. This allows for effective use of the space between the pair of lead terminals 220 of each energy storage element 21. As a result, the space consumed by the busbar 28 can be reduced, and the device itself can be made smaller.

[0066] The tip portion 222b (first tip portion) of the negative lead terminal 222 is provided with a connecting portion 222c that connects to the tip portion 221b (second tip portion) of the positive lead terminal 221, and a protruding portion 222d that extends from the tip portion 221b. Since the detection wire 36 is connected to this protruding portion 222d, the connection area for the detection wire 36 can be secured without reducing the size of the connecting portion 222c. Therefore, the detection wire 36 can be easily connected while suppressing an increase in the resistance of the connecting portion 222c.

[0067] In particular, when joining the detection wire 36 to the protruding portion 222d, ultrasonic welding can be easily performed because the joining area of ​​the detection wire 36 is secured. If the detection wire 36 can be joined by ultrasonic welding, mass production is easier to achieve compared to joining by soldering.

[0068] Even in a configuration where the negative lead terminal 222 and the positive lead terminal 221 are bent and the tip portions 222b and 221b are joined, the protruding portion 222d protrudes from the tip portion 221b along the Z-axis direction, thus ensuring a sufficient contact area for the detection line 36. Because the negative lead terminal 222 and the positive lead terminal 221 are bent, the amount of protrusion of the negative lead terminal 222 and the positive lead terminal 221 in the Y-axis direction can be reduced, enabling miniaturization in the Y-axis direction.

[0069] Since the protrusion 222d extends from the tip portion 221b in a direction away from the center in the Z-axis direction of the energy storage element 21, the protrusion 222d is positioned close to the outer edge of the outer film 210. In other words, the travel distance of the welding jig can be reduced, thus suppressing damage to the welding jig.

[0070] As in this embodiment, when the negative lead terminal 222 and positive lead terminal 221 are bent, the Y-axis dimension of the energy storage unit 20 is reduced, which restricts the installation space for the welding jig. In other words, there is a concern that the welding jig may come into contact with the outer film 210 or damage surrounding components. In particular, vibrations when the welding jig moves can be a cause. To alleviate these concerns, it is conceivable to suppress the movement speed of the welding jig, but this increases the movement time, making it difficult to perform welding work smoothly. Therefore, when the protrusion 222d is positioned close to the edge of the outer film 210, as in this embodiment, damage to the outer film 210 and other components can be suppressed even when there are restrictions on the installation space for the welding jig, and welding work can be performed smoothly.

[0071] Since the detection wire 36 is supported by a busbar 28 positioned between a pair of lead terminals 220 on each energy storage element 21, a separate member for supporting the detection wire is not required. This reduces the number of parts and allows for miniaturization of the device itself.

[0072] In the busbar 28, the area of ​​the first busbar surface 28a facing the negative Z-axis direction is smaller than the area of ​​the second busbar surface 28b facing the negative Y-axis direction. Therefore, heat from the busbar 28 is less likely to be transferred to each lead terminal 220. As a result, the increase in electrical resistance due to temperature rise at each lead terminal 220 can be suppressed, and thus the increase in electrical resistance of the energy storage element 21 can be suppressed.

[0073] [Explanation of variations] The following describes various modifications of the above embodiments. In the following description, parts identical to those in the above embodiments or other modifications may be denoted by the same reference numerals and their descriptions may be omitted.

[0074] (Variation 1) In the above embodiment, the case in which the first and second lead terminals are bent is illustrated, but the lead terminals do not have to be bent. Modification 1 describes the case in which the first and second lead terminals are not bent.

[0075] Figures 7A and 7B are explanatory diagrams showing the first lead terminal 312 and the second lead terminal 322 according to Modification 1. Figure 7A illustrates the first energy storage element 31 and the second energy storage element 32 arranged in the X-axis direction. Figure 7B is a plan view showing an enlarged view of the area enclosed by the dashed circle in Figure 7A. Here, the first energy storage element 31 is positioned in the negative X-axis direction relative to the second energy storage element 32.

[0076] The first energy storage element 31 comprises a first outer casing 311 and a first lead terminal 312 protruding in the negative Y-axis direction from the edge of the first outer casing 311 in the negative Y-axis direction. The first energy storage element 31 may also be provided with other lead terminals having a different polarity from the first lead terminal 312. The other lead terminals may protrude from the edge of the first outer casing 311 in the negative Y-axis direction, from the edge of the first outer casing 311 in the positive Y-axis direction, or from an edge in a direction other than the Y-axis direction.

[0077] The first lead terminal 312 is formed in a rectangular shape in plan view, extending in the negative direction of the Y-axis. In the first lead terminal 312, the end closest to the first outer casing 311 is the first base portion 312a, and the portion continuous with the first base portion 312a and beyond the first base portion 312a is the first tip portion 312b.

[0078] The second energy storage element 32 comprises a second casing 321 and a second lead terminal 322 protruding in the negative Y-axis direction from the edge of the second casing 321 in the negative Y-axis direction. The second energy storage element 32 may also be provided with other lead terminals having a different polarity from the second lead terminal 322. The other lead terminals may protrude from the edge of the second casing 321 in the negative Y-axis direction, from the edge of the second casing 321 in the positive Y-axis direction, or from an edge in a direction other than the Y-axis direction.

[0079] The second lead terminal 322 is formed in a rectangular shape in plan view, extending in the negative Y-axis direction. In the second lead terminal 322, the end closest to the second outer casing 321 is the second base portion 322a, and the portion continuous with the second base portion 322a and beyond it is the second tip portion 322b. The length of the second lead terminal 322 in the protruding direction (Y-axis direction) is shorter than the length of the first lead terminal 312 in the protruding direction.

[0080] When the first lead terminal 312 and the second lead terminal 322 are joined, the first base portion 312a and the second base portion 322a curve so that they move closer to each other, and the first tip portion 312b and the second tip portion 322b overlap and are joined together. The first tip portion 312b includes a joining portion 312c that overlaps and is joined to the second tip portion 322b, and a protruding portion 312d that protrudes from the second tip portion 322b in the negative Y-axis direction. The tip of the detection line 36 is joined to this protruding portion 312d.

[0081] Thus, even when the protruding portion 312d protrudes from the second tip portion 322b in the Y-axis direction (protruding direction), the detection wire 36 is joined to the protruding portion 312d, so the joining area of ​​the detection wire 36 can be secured without reducing the size of the joining portion 312c. Therefore, the detection wire 36 can be easily joined while suppressing an increase in resistance.

[0082] (others) Although an embodiment of the present invention, the energy storage device 1, has been described above, the present invention is not limited to the above-described embodiment. In other words, the embodiments disclosed herein are illustrative and not restrictive in all respects, and the scope of the present invention includes all modifications in the sense and scope equivalent to the claims.

[0083] In the above embodiment, a rectangular outer film 210 is shown as an example when viewed from the X-axis direction, but the outer shape of the outer film 210 can be anything. Other outer shapes of the outer film 210 include polygons other than rectangles, oval shapes, elliptical shapes, and circular shapes.

[0084] In the above embodiment, the example shown is that the protrusion 222d protrudes from the tip portion 221b in a direction away from the center in the Z-axis direction of the energy storage element 21, but the protrusion 222d may also protrude toward the center in the Z-axis direction of the energy storage element 21. The protrusion 222d may be provided on only one energy storage element 21, or not all energy storage elements 21 may be provided with the protrusion 222d.

[0085] In the above embodiment, an L-shaped busbar 28 was exemplified, but the shape of the busbar 28 can be anything as long as it extends along the first direction while being positioned between the pair of lead terminals 220 of the first energy storage element 21 and between the pair of lead terminals 220 of the second energy storage element 21. Other shapes of the busbar 28 include a straight shape, etc.

[0086] In the above embodiment, the case in which the busbar 28 supports all detection lines 36 was illustrated, but the busbar 28 may support only at least one detection line 36, or it may not support all detection lines 36.

[0087] In the above embodiment, the example given was that the area of ​​the first busbar surface 28a facing the negative Z-axis direction in the busbar 28 is smaller than the area of ​​the second busbar surface 28b facing the negative Y-axis direction. However, the area of ​​the first busbar surface 28a may be the same as the area of ​​the second busbar surface 28b, or the area of ​​the first busbar surface 28a may be larger than the area of ​​the second busbar surface 28b.

[0088] In the above embodiment, the energy storage element 21 is exemplified as a pouch-type energy storage element having a flat shape. However, the energy storage element 21 may be an energy storage element with a flat rectangular parallelepiped shape (square), cylindrical shape, oblong cylindrical shape, or elliptical cylindrical shape, rather than a pouch-type energy storage element.

[0089] The present invention also includes forms constructed by arbitrarily combining the components included in the embodiments and their modified examples. [Industrial applicability]

[0090] This invention can be applied to energy storage devices equipped with energy storage elements such as lithium-ion secondary batteries. [Explanation of Symbols]

[0091] 1. Energy storage device 10 Exterior 20 Energy storage units 21 Energy storage element 22 Retaining member 23 First retaining member 24 Second retaining member 27. Circuit board support section 28 Bus Bar 28a Busbar First Side 28b Busbar Second Side 31 First energy storage element 32 Second energy storage element 36 detection lines 210 Exterior film 220 Lead terminals 221 Positive lead terminal 221a Base (second base) 221b Tip (second tip) 222 Negative lead terminal 222a Base (first base) 222b Tip (first tip) 222c joint 222d Protrusion 311 First exterior body 312 First lead terminal 312a First base 312b First tip 312c joint 312d protrusion 321 Second exterior body 322 Second lead terminal 322a Second base 322b Second tip V1, V2 virtual lines

Claims

1. A first energy storage element and a second energy storage element are arranged in the first direction, The system comprises a busbar electrically connected to the first energy storage element and the second energy storage element, The first energy storage element is First outer casing, The first outer casing comprises a pair of first lead terminals that protrude from one edge of the first outer casing in a second direction intersecting the first direction, and are arranged in a third direction intersecting the first and second directions, The second energy storage element is The second outer casing, The second outer casing comprises a pair of second lead terminals that protrude in the second direction from one edge of the second outer casing and are aligned in the third direction, The busbar is positioned between the pair of first lead terminals and between the pair of second lead terminals, and extends along the first direction. Energy storage device.

2. Furthermore, it is equipped with detection lines for detecting the state of the first energy storage element and the second energy storage element, The detection line is supported by the busbar. The energy storage device according to claim 1.

3. Of the pair of first lead terminals, one of the first lead terminals comprises a first base and a first tip continuous with the first base. Of the pair of second lead terminals, the second lead terminal corresponding to one of the first lead terminals comprises a second base and a second tip continuous with the second base. The first tip portion comprises a joining portion that is joined to the second tip portion, and a protruding portion that extends from the second tip portion in a direction intersecting the first direction. The detection line is joined to the protruding portion. The energy storage device according to claim 2.

4. The area of ​​the surface of the busbar facing the third direction is smaller than the area of ​​the surface of the busbar facing the second direction. The energy storage device according to claim 1 or 2.

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