bus bar

Abstract

A busbar is provided. The busbar includes a first joint portion that is joined to an output terminal of a first battery, a second joint portion that is joined to an output terminal of a second battery, and a protruding portion that is disposed between the first joint portion and the second joint portion and protrudes in a stacking direction of the battery and the busbar. The protruding portion includes a first inclined portion that extends from the first joint portion in a direction in which the battery is approached or distanced, and a second inclined portion that extends from the second joint portion in the direction in which the battery is approached or distanced. The first inclined portion and the second inclined portion are arranged with a given interval W being left therebetween, and the interval gradually widens from one end side toward the other end side.

Description

[0001] This application is a divisional application of the invention application filed on March 11, 2019, with the international filing date of 2019 and the national application number of 201980022149.0, entitled "Busbar and Battery Stack". Technical Field

[0002] This invention relates to busbars and battery stacks. Background Technology

[0003] For example, batteries used in vehicles and other applications requiring high output voltages are known to be battery stacks formed by electrically connecting multiple batteries. In the past, in such battery stacks, the output terminals of adjacent batteries were connected to each other using busbars.

[0004] Busbars with a structure having multiple stacked plates are known (see, for example, Patent Document 1). By achieving this stacked structure, the rigidity of the busbar can be suppressed. Consequently, the busbar can absorb the forces exerted on the connection between the busbar and the battery due to battery vibrations, etc. As a result, the reliability of the connection between the busbar and the battery can be improved.

[0005] Prior technology documents

[0006] Patent documents

[0007] Patent Document 1: JP 2012-18904 Summary of the Invention

[0008] In recent years, the trend towards higher battery capacity has led to an increase in battery expansion. Battery expansion results in significant dimensional changes, particularly in the stacking direction. Consequently, the load on the connection between the busbar and the battery tends to increase. To address this, a protrusion that bends relative to the battery in the direction of approach or distance from the busbar is considered. This increases the busbar's flexibility in the tensile direction, thus mitigating the increased load on the connection.

[0009] The inventors of this invention, through dedicated research into the results of providing protrusions in a plate-stacked busbar, recognized the following issues: When plates with protrusions of the same shape are stacked, gaps may form between the plates. These gaps can hinder the welding process. If welding becomes unstable due to these gaps, the resistance of the busbar increases, potentially leading to a decrease in the output characteristics of the battery stack. Furthermore, the size of the busbar in the plate-stacking direction may increase due to the gaps between the plates.

[0010] To stack the plates without gaps, protrusions of different sizes are needed on the outer side of the bend and the inner side of the bend. However, this requires preparing multiple molds corresponding to the shapes of the plates, which may increase the manufacturing cost of the busbar.

[0011] The present invention was made in view of the following situation, and its object is to provide a technique for suppressing the generation of gaps between plates and the increase in manufacturing costs, and for improving the flexibility of plate-laminated busbars.

[0012] One aspect of the present invention is a busbar. This busbar has a structure with multiple stacked plates, electrically connecting a first battery and a second battery, and includes: a first engagement portion engaging with the output terminal of the first battery; a second engagement portion engaging with the output terminal of the second battery; and a protrusion disposed between the first and second engagement portions and protruding in the stacking direction of the batteries and the busbar. The protrusion has: a first inclined portion extending from the first engagement portion in a direction approaching or away from the battery; and a second inclined portion extending from the second engagement portion in a direction approaching or away from the battery. The first and second inclined portions are arranged such that a given interval is left between the first and second engagement portions in the first direction in which they are arranged, and this interval gradually widens from one end of a second direction intersecting the first direction towards the other end when viewed from the stacking direction.

[0013] Another aspect of the present invention is a battery stack. This battery stack includes: the busbar of the above-described embodiment; and a plurality of batteries electrically connected to each other via the busbar.

[0014] According to the present invention, the generation of gaps between plates and the increase in manufacturing costs can be suppressed, and the flexibility of the plate-stacked busbar can be improved. Attached Figure Description

[0015] Figure 1 This is a perspective view showing the schematic structure of the battery stack involved in the embodiment.

[0016] Figure 2 It is a three-dimensional diagram showing the general structure of the busbar.

[0017] Figure 3 It is a top view showing the general structure of the busbar.

[0018] Figure 4 (A) is a three-dimensional diagram showing the schematic structure of the plate-laminated body formed during the manufacturing process of the busbar. Figure 4 (B) is a side view showing the schematic structure of the plate laminate. Detailed Implementation

[0019] The present invention will now be described with reference to suitable embodiments and the accompanying drawings. These embodiments are not intended to limit the invention but are illustrative; all features and combinations thereof described in the embodiments are not necessarily limited to the essential content of the invention. Identical or equivalent constituent elements, components, and processes shown in the various drawings are labeled with the same reference numerals, and repeated descriptions are omitted where appropriate. Furthermore, the scales and shapes of the parts shown in the various drawings are set for ease of explanation and are not intended to be limiting unless specifically mentioned. Additionally, even for the same components, there may be some differences in scale and other parameters between the various drawings. Furthermore, the use of terms such as "first," "second," etc., in this specification or claims does not indicate any order or importance unless specifically mentioned, but is used to distinguish one structure from others.

[0020] Figure 1 This is a perspective view showing the schematic structure of the battery stack according to the embodiment. The battery stack 1 includes a plurality of busbars 2 and a plurality of batteries 4 electrically connected to each other through the busbars 2.

[0021] Each battery 4 is, for example, a rechargeable secondary battery such as a lithium-ion battery, a nickel-metal hydride battery, or a nickel-cadmium battery. Battery 4 is a so-called square battery, having a flat, rectangular outer casing. A roughly rectangular opening is provided on one side of the outer casing, through which electrodes, electrolyte, etc., are contained. A sealing plate 6 is provided at the opening of the outer casing to seal it.

[0022] On the sealing plate 6, a positive output terminal 8 is provided at one end near the long side, and a negative output terminal 8 is provided at the other end. Hereinafter, the positive output terminal 8 will be referred to as positive terminal 8a, and the negative output terminal 8 as negative terminal 8b. Alternatively, when it is not necessary to distinguish the polarity of the output terminals 8, positive terminal 8a and negative terminal 8b will be collectively referred to as output terminal 8. The outer can, sealing plate 6, and output terminals 8 are conductive materials, for example, made of metal. Furthermore, a safety valve (not shown) is provided on the sealing plate 6 between the pair of output terminals 8. The safety valve is configured to open when the internal pressure of the outer can rises above a given value, thereby releasing the internal gas.

[0023] In this embodiment, the side with the output terminal 8 is designated as the upper surface of the battery 4, and the opposite side is designated as the bottom surface of the battery 4. Furthermore, the battery 4 has two main surfaces connecting the upper and bottom surfaces. These main surfaces are the largest of the six surfaces of the battery 4. The remaining two surfaces besides the upper surface, bottom surface, and two main surfaces are designated as the side surfaces of the battery 4. Additionally, the upper surface of the battery 4 is designated as the upper surface of the battery stack 1, the bottom surface of the battery 4 is designated as the bottom surface of the battery stack 1, and the side surfaces of the battery 4 are designated as the side surfaces of the battery stack 1. For convenience, the upper surface of the battery stack 1 is positioned vertically upwards, and the bottom surface of the battery stack 1 is positioned vertically downwards.

[0024] Multiple batteries 4 are stacked with their main surfaces facing each other at a given interval. "Stacking" refers to arranging multiple components in any direction. Therefore, the stacking of batteries 4 also includes arranging multiple batteries 4 horizontally. Furthermore, each battery 4 is configured so that its output terminals 8 face the same direction. Here, for convenience, the output terminals 8 are oriented vertically upwards. Two adjacent batteries 4 are stacked such that the positive terminal 8a of one side and the negative terminal 8b of the other side are adjacent. The positive terminal 8a and the negative terminal 8b are electrically connected via a busbar 2. Additionally, there are cases where the output terminals of adjacent batteries 4 of the same polarity are connected to each other using a busbar.

[0025] Busbar 2 is a roughly strip-shaped metal component. Busbar 2 is electrically connected to the output terminals 8 of each battery 4, for example, by welding. The structure of busbar 2 will be described in detail later.

[0026] The battery stack 1 has multiple separators (not shown). Separators, also referred to as insulating spacers, are, for example, made of insulating resin. Separators are disposed between each battery 4 and between the battery 4 and the end plate 10 (described later). Thus, the outer casings of adjacent batteries 4 are insulated from each other. Furthermore, the outer casings of the battery 4 and the end plate 10 are insulated.

[0027] Additionally, the battery stack 1 has a pair of end plates 10. The end plates 10 may include, for example, metal plates. Multiple stacked batteries 4 and multiple separators are sandwiched between the pair of end plates 10. The pair of end plates 10 are arranged adjacent to each other in the stacking direction of the batteries 4 (hereinafter referred to as battery stacking direction X), sandwiching the outermost battery 4 and the separators. Furthermore, the outermost busbar 2 in the battery stacking direction X also functions as an external connection terminal.

[0028] Additionally, the battery stack 1 has a pair of binding members 12. The stacked batteries 4, separators, and end plates 10 are bound by the pair of binding members 12. The pair of binding members 12 are also referred to as straps. The pair of binding members 12 are positioned in the horizontal direction Y (orthogonal to the battery stacking direction X). Figure 1The direction indicated by arrow Y is the center. The horizontal direction Y is the direction in which the output terminals 8 in each battery 4 are arranged. Each restraining member 12 has: a rectangular flat portion 12a parallel to the side of the battery 4; and an eave portion 12b protruding from the end of each side of the flat portion 12a toward the battery 4. The restraining member 12 can be formed, for example, by bending each side of a rectangular metal plate.

[0029] Two opposing eaves 12b and a pair of end plates 10 in the battery stacking direction X are fixed by screw clamps or the like. Thus, multiple batteries 4 and multiple separators are fastened by the pair of end plates 10 and the pair of binding members 12. Multiple batteries 4 are clamped in the battery stacking direction X by the binding members 12, and are positioned in the battery stacking direction X. Furthermore, multiple batteries 4 are positioned vertically by having their bottom surfaces abut against the lower eaves 12b of the binding member 12 through an insulator, and their upper surfaces abut against the upper eaves 12b of the binding member 12 through an insulator. Additionally, a portion of the separator can be used as an insulator between the bottom surface and / or the upper surface and the eaves 12b. In this state, the battery stack 1 is obtained by electrically connecting the busbar 2 to the output terminals 8 of each battery 4.

[0030] Next, the busbar 2 involved in this embodiment will be described in detail. Figure 2 It is a three-dimensional diagram showing the general structure of the busbar. Figure 3 This is a top view showing the schematic structure of the busbar. The busbar 2 has a structure with multiple stacked plates 14. Each plate 14 is strip-shaped and extends in the battery stacking direction X. Each plate 14 contains metals such as copper and aluminum, and has a thickness of, for example, 0.1 to 0.5 mm.

[0031] The busbar 2 includes a first joint 16, a second joint 18, and a protrusion 20. Each plate 14 has a region that forms part of the first joint 16, the second joint 18, and the protrusion 20. The first joint 16, the second joint 18, and the protrusion 20 are formed by stacking multiple plates 14. Therefore, the first joint 16, the second joint 18, and the protrusion 20 have approximately the same thickness.

[0032] The first joint 16 engages with the output terminal 8 of the first battery 4a (reference). Figure 1 The second joint 18 engages with the output terminal 8 of the second battery 4b (see reference). Figure 1 This electrically connects the first battery 4a and the second battery 4b. The first joint 16 is located at one end of the busbar 2, and the second joint 18 is located at the other end of the busbar 2. The first joint 16 and the second joint 18 are flat.

[0033] The protrusion 20 is disposed between the first joint 16 and the second joint 18, protruding in the stacking direction of the battery 4 and the busbar 2 (hereinafter referred to as the busbar stacking direction Z). In this embodiment, for convenience, the busbar stacking direction Z is set to a vertical direction. In other words, the protrusion 20 protrudes in the stacking direction of the plate 14.

[0034] The protrusion 20 has a first inclined portion 22 and a second inclined portion 24. The first inclined portion 22 extends from the first joint 16 in a direction approaching or away from the battery 4. That is, the first inclined portion 22 extends in a direction intersecting the plane direction (XY plane direction) parallel to the first joint 16. The first inclined portion 22 is a surface inclined at a given angle relative to the first joint 16. The second inclined portion 24 extends from the second joint 18 in a direction approaching or away from the battery 4. That is, the second inclined portion 24 extends in a direction intersecting the plane direction (XY plane direction) parallel to the second joint 18. The second inclined portion 24 is a surface inclined at a given angle relative to the second joint 18.

[0035] In the first inclined portion 22 and the second inclined portion 24, if one extends close to the battery 4, the other also extends close to the battery 4; if one extends away from the battery 4, the other also extends away from the battery 4. In this embodiment, the first inclined portion 22 and the second inclined portion 24 extend away from the battery 4. Therefore, the protrusion 20 has a cross-sectional shape approximately U-shaped in the planar direction (XZ plane direction) including the battery stacking direction X and the busbar stacking direction Z.

[0036] Furthermore, the first inclined portion 22 and the second inclined portion 24 are arranged with a given interval W between them in the first direction in which the first joint portion 16 and the second joint portion 18 are arranged. Additionally, the first inclined portion 22 and the second inclined portion 24 are arranged such that the interval W gradually increases from one end of a second direction intersecting the first direction towards the other end, viewed from the busbar stacking direction Z. In this embodiment, the first direction is the battery stacking direction X, and the second direction is the horizontal direction Y. That is, in the first inclined portion 22, one end 22a in the horizontal direction Y is located closer to the second joint portion 18 than the other end 22b, and the other end 22b is located closer to the first joint portion 16 than one end 22a. Similarly, in the second inclined portion 24, one end 24a in the horizontal direction Y is located closer to the first joint portion 16 than the other end 24b, and the other end 24b is located closer to the second joint portion 18 than one end 24a.

[0037] The connection angle θ1 between the first inclined portion 22 and the first joint portion 16 is the same from one end 22a to the other end 22b. Similarly, the connection angle θ2 between the second inclined portion 24 and the second joint portion 18 is the same from one end 24a to the other end 24b. That is, the angular changes of the connection between the first joint portion 16 and the first inclined portion 22, and the connection between the second joint portion 18 and the second inclined portion 24, from the first joint portion 16 side toward the second joint portion 18 side, are the same in all second-direction positions.

[0038] Additionally, the protrusion 20 has a flat portion 26 between the first inclined portion 22 and the second inclined portion 24. The flat portion 26 extends parallel to the first joint portion 16 and the second joint portion 18. The flat portion 26 and the first joint portion 16 are connected by the first inclined portion 22, and the flat portion 26 and the second joint portion 18 are connected by the second inclined portion 24. Therefore, the flat portion 26, the first joint portion 16, and the second joint portion 18 are offset from the height of the first inclined portion 22 and the second inclined portion 24 (the length of the busbar stacking direction Z) by a corresponding amount in the busbar stacking direction Z. Furthermore, the flat portion 26 is trapezoidal. More specifically, the flat portion 26 is an isosceles trapezoid with the side connected to the first inclined portion 22 as one leg and the side connected to the second inclined portion 24 as the other leg.

[0039] Busbar 2 is manufactured, for example, as follows. Figure 4 (A) is a three-dimensional diagram showing the schematic structure of the plate-laminated body formed during the manufacturing process of the busbar. Figure 4 (B) is a side view showing the schematic structure of the plate laminate.

[0040] First, multiple plates 14 are manufactured, each having a first joint 16, a second joint 18, and a protrusion 20. For example, a strip-shaped flat plate is bent using a pressing process to create two steps with a gap W along its long side, thus obtaining the plate 14. One step forms the first inclined portion 22, and the other step forms the second inclined portion 24. The portion sandwiched between the two steps forms the flat portion 26. The remaining portion forms the first joint 16 and the second joint 18. Each plate 14 is formed using the same mold, therefore having the same shape.

[0041] Next, the obtained plates 14 are stacked to form a plate stack 28. For example... Figure 4 (A) and Figure 4As shown in (B), in the plate stack 28, each plate 14 overlaps in a staggered manner in the horizontal direction Y. Thus, two adjacent plates 14 overlap with the narrow and wide portions of the interval W between the first inclined portion 22 and the second inclined portion 24. Specifically, in the protrusion direction of the protrusion 20, the outer plate located on the front end side and the inner plate located on the root side overlap with the wide portion of the interval W in the outer plate and the narrow portion of the interval W in the inner plate.

[0042] The gap W between the first inclined portion 22 and the second inclined portion 24 includes a gap between their outer surfaces (hereinafter appropriately referred to as outer gap WO) and a gap between their inner surfaces (hereinafter appropriately referred to as inner surface gap WI). In the first inclined portion 22, the outer surface is the surface facing the first joint portion 16, and the inner surface is the surface facing the second inclined portion 24. In the second inclined portion 24, the outer surface is the surface facing the second joint portion 18, and the inner surface is the surface facing the first inclined portion 22. In each plate 14, the outer gap WO and the inner surface gap WI have a difference corresponding to the thickness of the plate 14.

[0043] In contrast, adjacent outer and inner plates are stacked with their spacing corresponding to the difference between the outer spacing WO and the inner spacing WI offset in the horizontal direction Y. Thus, the protrusions 20 of the outer and inner plates overlap in portions where the inner spacing WI in the outer plate and the outer spacing WO in the inner plate are approximately the same. If the outer spacing WO or the inner spacing WI are compared, the wider portion of the spacing W in the outer plate overlaps with the narrower portion of the spacing W in the inner plate.

[0044] As a result, at least in each planar region of the first joint 16, the first inclined portion 22, the flat portion 26, the second joint 18, and the second inclined portion 24, the outer surface of the inner plate and the inner surface of the outer plate can abut without gap. The so-called planar region is the region excluding the region of the buckled shape that connects the first joint 16 and the first inclined portion 22, the first inclined portion 22 and the flat portion 26, the second joint 18 and the second inclined portion 24, and the second inclined portion 24 and the flat portion 26, respectively.

[0045] Next, the multiple plates 14 are joined by welding or the like. Preferably, the joining of the multiple plates 14 is only performed in the planar regions of the first joint 16 and the second joint 18. That is, it is preferable not to provide joints of the multiple plates 14 in the protrusion 20 of the busbar 2. This ensures the flexibility of the protrusion 20 more reliably. Then, the two ends in the horizontal Y direction are cut off, leaving only the area where all the plates 14 overlap in the plate stack 28. This results in... Figures 1-3The busbar 2 is shown. Furthermore, if both ends of the plate laminate 28 in the horizontal Y direction are cut off, multiple plates 14 are joined at the center of the plate 14 in the width direction (horizontal Y direction). In this case, through welding is used, for example, in joining the multiple plates 14.

[0046] As explained above, the busbar 2 according to this embodiment has a structure of stacked multiple plates 14, and is a busbar that electrically connects the first battery 4a and the second battery 4b. The busbar 2 has: a first engagement portion 16 that engages with the output terminal 8 of the first battery 4a; a second engagement portion 18 that engages with the output terminal 8 of the second battery 4b; and a protrusion 20 disposed between the first engagement portion 16 and the second engagement portion 18. The protrusion 20 protrudes in the busbar stacking direction Z.

[0047] The protrusion 20 has: a first inclined portion 22 extending from the first joint 16 in a direction approaching or away from the battery 4; and a second inclined portion 24 extending from the second joint 18 in a direction approaching or away from the battery 4. The first inclined portion 22 and the second inclined portion 24 are arranged with a given interval W between them in the first direction in which the first joint 16 and the second joint 18 are arranged. In addition, the relative orientations of the first inclined portion 22 and the second inclined portion 24 are determined such that, viewed from the busbar stacking direction Z, the interval W gradually increases from one end of a second direction intersecting the first direction toward the other end. In other words, the interval W gradually changes from one end of the busbar 2 in the width direction toward the other end.

[0048] Therefore, the stacked plates 14 can be offset in the second direction, so that the narrower portion of the protrusion 20 of one plate 14 coincides with the wider portion of the protrusion 20 of the other plate 14. As a result, even when each plate 14 has protrusions 20 of the same shape, gaps between the plates 14 can be avoided. For this purpose, multiple plates 14 can be manufactured using the same mold.

[0049] Therefore, according to this embodiment, the generation of gaps between the plates 14 and the increase in manufacturing cost of the busbar 2 can be suppressed, and a protrusion 20 is provided in the plate-stacked busbar 2. Furthermore, by providing the protrusion 20, the flexibility of the busbar 2 in the battery stacking direction X can be improved. Moreover, since the displacement of the battery 4 can be absorbed by the deformation of the protrusion 20, the load on the connection between the busbar 2 and the output terminal 8 can be reduced more reliably. Therefore, a stable electrical connection between the batteries 4 via the busbar 2 can be achieved. In addition, by providing the busbar 2 of this embodiment in the battery stack 1, the performance of the battery stack 1 can be improved.

[0050] Furthermore, the connection angle θ1 between the first inclined portion 22 and the first joint portion 16, and the connection angle θ2 between the second inclined portion 24 and the second joint portion 18, are the same from one end to the other in the second direction. In other words, the connection angles θ1 and θ2 are the same from one end to the other in the width direction of the busbar 2. This can suppress the stacked plates 14 from being misaligned with each other in the battery stacking direction X. If the misalignment in the battery stacking direction X is permissible, the connection angles θ1 and θ2 may also be different from one end to the other in the width direction of the busbar 2.

[0051] Furthermore, the protrusion 20 has a flat portion 26 between the first inclined portion 22 and the second inclined portion 24. This reduces the protrusion height of the protrusion 20. Therefore, the increase in the size of the busbar 2 caused by the protrusion 20 can be suppressed. In addition, compared with the case where the protrusion 20 is integrally curved from the first joint 16 side to the second joint 18 side, the size management of the busbar 2 is easier. Furthermore, the flat portion 26 can also be used as a connection portion for voltage detection lines.

[0052] This invention is not limited to the embodiments described above. Various design changes and modifications can be made based on the knowledge of those skilled in the art, and the modified embodiments are also included within the scope of this invention. New embodiments resulting from adding modifications to the above embodiments combine the effects of both combined embodiments and individual modifications.

[0053] In the above embodiment, the battery 4 is a square battery, but the shape of the battery 4 is not particularly limited, and it can also be cylindrical or the like. Furthermore, the total number of batteries 4 included in the battery stack 1 is not particularly limited. Additionally, the outer casing of the battery 4 can be covered with an insulating sheet such as a shrink tubing. Furthermore, the number of plates 14 constituting the busbar 2 is not particularly limited. The number of plates 14 can be appropriately set according to the required thickness of the busbar 2.

[0054] In this embodiment, the interval W between the first inclined portion 22 and the second inclined portion 24 continuously increases from one end to the other in the horizontal direction Y, but it can also increase in stages. Additionally, the protrusion 20 protrudes in a direction away from the battery 4, but it can also protrude in a direction closer to the battery 4. Furthermore, the protrusion 20 may not have the flat portion 26, and for example, it may be a shape that is integrally curved from the first joint portion 16 side to the second joint portion 18 side.

[0055] In this embodiment, a structure is shown in which both ends in the horizontal direction Y are cut off, leaving only the area where all the plates 14 overlap in the plate laminate 28, but this structure is not particularly limited. For example, only one end in the horizontal direction Y may be cut off, or neither end may be cut off. Alternatively, only a portion of the ends of the plate laminate 28 may be cut off.

[0056] When the stepped portion of the plate 14 remains on the busbar 2, the plates 14 can be joined together by brazing, plating, or other processes on the stepped portion. This allows for reliable joining between the plates 14. Furthermore, when the stepped portion remains in the area corresponding to the first joint 16 and the second joint 18, the first joint 16 and the second joint 18 can be joined to the output terminal 8 using the stepped portion. For example, the stepped portion and the output terminal 8 can be joined by brazing or the like. This allows for more reliable joining between the busbar 2 and the output terminal 8.

[0057] Any combination of the above-mentioned constituent elements, whether varied among methods, apparatuses, systems, etc., is also valid as a manifestation of the present invention.

[0058] Explanation of reference numerals in the attached figures

[0059] 1 Battery stack

[0060] 2 busbars

[0061] 4 batteries

[0062] 4a First Battery

[0063] 4b Second Battery

[0064] 8 output terminals

[0065] 14 plates

[0066] 16 First joint

[0067] 18 Second joint

[0068] 20 protrusions

[0069] 22 First inclined section

[0070] 24 Second inclined section

[0071] 26. Flat area.

Claims

1. A busbar electrically connecting a first battery and a second battery, The bus bar has the following features: The first engagement portion engages with the output terminal of the first battery; The second engagement portion engages with the output terminal of the second battery; A first inclined portion is disposed between the first joint and the second joint and extends from the first joint in a direction toward or away from the battery; and A second inclined portion is disposed between the first joint and the second joint and extends from the second joint in a direction toward or away from the battery. When the busbar is viewed from the direction in which the busbar and the batteries are arranged, the first inclined portion and the first connecting portion are adjacent to each other in the direction in which the first battery and the second battery are arranged, and the second inclined portion and the second connecting portion are adjacent to each other in the direction in which the first battery and the second battery are arranged. When the busbar is viewed from the direction in which the busbar and the batteries are arranged, the first boundary of the first joint and the first inclined portion intersects with the direction in which the first battery and the second battery are arranged; similarly, the second boundary of the second joint and the second inclined portion intersects with the direction in which the first battery and the second battery are arranged. When the busbar is viewed from the direction in which the busbar and the batteries are arranged, the distance between the first boundary and the second boundary in the direction in which the first battery and the second battery are arranged increases or decreases along a direction orthogonal to the direction in which the first battery and the second battery are arranged.

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