Bus bar and power storage unit

Abstract

To relieve stress applied to a joint between a bus bar and a terminal.SOLUTION: A bus bar 1 disclosed herein includes a first bonding region 10 bonded to a terminal portion 144 of a first power storage device 100A, a second bonding region 20 bonded to a terminal portion 144 of a second power storage device 100B different from the first power storage device 100A, and a bridging region 30 connecting the first bonding region 10 and the second bonding region 20. At least one of the first bonding region 10 and the second bonding region 20 is provided with buffer portions 12, 22 that absorb stress S caused by fluctuations in the gap G between the first bonding region 10 and the second bonding region 20. The bus bar 1 configured in this manner can reduce stress on bonding portions W1, W2 between the bus bar 1 and the terminal portion 144.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a busbar and a power storage unit. [Background technology]

[0002] Energy storage devices such as lithium-ion secondary batteries are used as power sources for various electrical appliances. In this case, a power storage unit may be constructed by connecting multiple energy storage devices with a bus bar. An example of this bus bar is disclosed in Patent Document 1 (JP Patent Publication No. 2020-021628). The bus bar described in Patent Document 1 is a conductive member that connects multiple terminals. This bus bar is formed by stacking multiple conductive plates, and has a curved portion that is curved in the stacking direction of the conductive plates between multiple connection parts that are connected to multiple terminals. A bus bar with such a configuration can follow the variation in the distance between the terminals due to the expansion and contraction of the single battery (energy storage device) because the curved portion deforms when stress is applied. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2020-021628 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, busbars are joined to the terminals of the power storage device by laser welding, resistance welding, or the like. When the distance between the terminals varies due to expansion and contraction of the power storage device, stress may be applied not only to the busbar body but also to the joints between the busbar and the terminals. As described above, the busbar described in Patent Document 1 can reduce stress applied to the busbar body by using the curved portion between the two joints. However, with a busbar having such a configuration, it is difficult to reduce stress applied to the joints between the busbar and the terminals. [Means for solving the problem]

[0005] In order to solve the above problems, a bus bar having the following configuration is provided.

[0006] The busbar disclosed herein has a first joint region joined to a terminal portion of a first power storage device, a second joint region joined to a terminal portion of a second power storage device different from the first power storage device, and a bridging region connecting the first and second joint regions. In this busbar, at least one of the first and second joint regions is provided with a buffer portion that absorbs stress caused by fluctuations in the distance between the first and second joint regions.

[0007] In the busbar having the above configuration, at least one of the first and second joint regions is provided with a buffer portion that absorbs stress caused by variation in the distance between the first and second joint regions, thereby making it possible to prevent stress caused by variation in the distance between the two joint regions from being applied to the joint between the busbar and the terminal portion. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view illustrating a bus bar according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view that illustrates a schematic connection between the bus bar illustrated in FIG. 1 and a terminal portion of an electricity storage device. [Diagram 3] FIG. 3 is a perspective view illustrating a schematic configuration of the electricity storage unit according to the first embodiment. [Figure 4] FIG. 4 is a perspective view that illustrates a schematic diagram of the electricity storage device in FIG. [Diagram 5] FIG. 5 is an enlarged cross-sectional view that illustrates a schematic structure of the vicinity of a terminal mounting hole of the electricity storage device illustrated in FIG. [Figure 6] FIG. 6 is an enlarged cross-sectional view illustrating a procedure for producing the insulating material in FIG. [Figure 7] FIG. 7 is an enlarged cross-sectional view that illustrates a connection structure of the electricity storage unit illustrated in FIG. [Figure 8] FIG. 8 is a cross-sectional view that illustrates a schematic connection between a bus bar according to another embodiment and a terminal portion of an electricity storage device. [Figure 9] FIG. 9 is a plan view of a bus bar according to another embodiment. [Figure 10] FIG. 10 is a plan view of a bus bar according to another embodiment. [Figure 11] FIG. 11 is a plan view of a bus bar according to another embodiment. [Figure 12] FIG. 12 is an enlarged cross-sectional view illustrating a schematic structure in the vicinity of a terminal mounting hole of an electricity storage device of an electricity storage unit according to another embodiment. [Figure 13] FIG. 13 is an enlarged cross-sectional view illustrating a schematic structure in the vicinity of a terminal mounting hole of an electricity storage device of an electricity storage unit according to another embodiment. [Figure 14] FIG. 14 is an enlarged cross-sectional view illustrating a schematic structure in the vicinity of a terminal mounting hole of an electricity storage device of an electricity storage unit according to another embodiment. [Figure 15] FIG. 15 is an enlarged cross-sectional view illustrating a connection structure of an electricity storage unit according to another embodiment. [Figure 16] FIG. 16 is an enlarged cross-sectional view illustrating a connection structure of an electricity storage unit according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments of the technology disclosed herein will be described with reference to the drawings. Note that matters other than those specifically mentioned in this specification and necessary for implementing the technology disclosed herein (such as the detailed configuration of the electrode body) can be understood as design matters for a person skilled in the art based on the conventional technology in the field. The technology disclosed here can be implemented based on the contents disclosed in this specification and the technical common sense in the field. In addition, the expression "A to B" indicating a range in this specification includes the meaning of "greater than A" and "smaller than B" as well as the meaning of A or more and B or less.

[0010] In this specification, the term "electricity storage device" refers to a concept that includes a device in which a charge / discharge reaction occurs by the movement of charge carriers between a pair of electrodes (positive and negative electrodes). That is, the electricity storage device in the technology disclosed herein includes secondary batteries such as lithium ion secondary batteries, nickel hydrogen batteries, and nickel cadmium batteries, as well as capacitors such as lithium ion capacitors and electric double layer capacitors.

[0011] <First embodiment> 1. Busbar configuration Hereinafter, an embodiment of the busbar disclosed herein will be described with reference to FIG. 1 and FIG. 2. FIG. 1 is a perspective view that shows a busbar according to a first embodiment. FIG. 2 is a cross-sectional view that shows a schematic connection between the busbar shown in FIG. 1 and a terminal portion of an electricity storage device. In addition, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom, respectively. In addition, the symbols X, Y, and Z in the drawings represent the width direction, depth direction, and height direction of the busbar, respectively. However, these are merely directions defined for convenience of explanation, and do not limit the use mode of the busbar disclosed herein. In addition, for convenience of explanation, in FIG. 2, only the terminal portion 144 is shown for the first electricity storage device 100A and the second electricity storage device 100B, and other portions are omitted.

[0012] 1 and 2, the busbar 1 according to this embodiment has a first joint region 10 joined to a terminal portion 144 of a first power storage device 100A, a second joint region 20 joined to a terminal portion 144 of a second power storage device 100B different from the first power storage device 100A, and a bridging region 30 connecting the first joint region 10 and the second joint region 20. In this busbar 1, buffer portions 12, 22 are provided in the first joint region 10 and the second joint region 20 to absorb stress S caused by a change in the gap G between the first joint region 10 and the second joint region 20. This makes it possible to reduce stress on joint portions W1, W2 between the busbar 1 and the terminal portion 144. Hereinafter, the busbar 1 having such a configuration will be specifically described.

[0013] (1) Overall structure As shown in FIG. 2, the busbar 1 according to this embodiment is a conductive member that connects the terminal portions 144 of two power storage devices (the first power storage device 100A and the second power storage device 100B). The material of the busbar 1 only needs to have a certain level of conductivity, and any conventionally known conductive material can be used without any particular restrictions. Examples of the material of the busbar 1 include metal materials such as aluminum, copper, iron, zinc, silver, and nickel. The material of the busbar 1 may also be an alloy of these metals. The busbar 1 may also be a clad material in which a plurality of layers made of different metal materials are laminated. In addition, in consideration of the bondability with the terminal portion 144 of the power storage device, the busbar 1 is preferably made of the same type of metal material as the terminal portion 144. For example, aluminum or the like is used for the terminal portion 144 on the positive electrode side of the power storage device. In this case, the busbar 1 is preferably made of aluminum or an aluminum alloy.

[0014] The busbar 1 according to this embodiment has a first joint region 10, a second joint region 20, and a bridging region 30. Specifically, the busbar 1 shown in Fig. 1 is a long plate-like member extending along the width direction X. In this busbar 1, the first joint region 10, the bridging region 30, and the second joint region 20 are arranged in this order from the left L to the right R in the width direction X. Each region will be described below.

[0015] (2) First joining area 10 The first joining region 10 is a region to be joined to the terminal portion 144 of the first power storage device 100A. As shown in FIG. 1, the first joining region 10 is formed at one end (left side L) in the width direction X of the busbar 1. Then, as shown in FIG. 2, a part of the first joining region 10 (a contact portion 14 described later) is joined to the terminal portion 144 of the first power storage device 100A. A conventionally known joining process (laser welding, resistance welding, ultrasonic joining, etc.) is used to join the first joining region 10 and the terminal portion 144. As a result, a joining portion W1 is formed that straddles the first joining region 10 (the contact portion 14) and the terminal portion 144. Although not shown in the drawings, the joining portion W1 is an annular joining portion in a plan view.

[0016] In the busbar 1 according to this embodiment, the first joint region 10 is provided with a buffer portion 12 that absorbs stress S caused by variation in the gap G between the first joint region 10 and the second joint region 20. This makes it possible to suppress the stress S applied to the joint W1. An example of the structure of the buffer portion 12 will be described below.

[0017] First, the first joining region 10 has a plate-shaped joining base portion. Hereinafter, the joining base portion in the first joining region 10 is referred to as the "first base portion 11". In this embodiment, the buffer portion 12 is configured as a step protruding from the first base portion 11. Specifically, the step-shaped buffer portion 12 protrudes from the first base portion 11 toward the terminal portion 144 of the first electricity storage device 100A (i.e., downward D in the height direction Z). This step-shaped buffer portion 12 deforms when a stress S along the width direction X is applied, and therefore, the stress S can be prevented from being directly applied to the joining portion W1.

[0018] More specifically, the stepped buffer section 12 has a protruding section 13 protruding downward D from the first base section 11, and a contact section 14 provided at a tip (lower end) 13a of the protruding section 13 and contacting the terminal section 144. The contact section 14 is a plate-like member extending along a planar direction (width direction X and depth direction Y). The bond section W1 on the first bond region 10 side extends in the height direction Z so as to straddle the contact section 14 and the terminal section 144. The protruding section 13 also extends in the height direction Z so as to connect the contact section 14 and the first base section 11. The buffer section 12 having such a configuration can particularly suitably relieve the stress S on the bond section W1. Specifically, it is as follows. First, when the first electricity storage device 100A or the second electricity storage device 100B expands and contracts, the interval G between the first bond region 10 and the second bond region 20 changes. As a result, stress S is applied to the first joint region 10 in the planar directions (width direction X and depth direction Y). However, the buffer section 12 according to this embodiment has a protrusion 13 extending in the height direction Z. This protrusion 13 deforms preferentially when stress S is applied in the planar direction, and is therefore able to absorb the stress S. This makes it possible to prevent stress S in the width direction X from being applied to the joint W1 extending in the height direction Z.

[0019] In addition, the thickness t1 of the protrusion 13 (the dimension of the protrusion 13 in the width direction X) is preferably smaller than the thickness t2 of the contact portion 14 (the dimension of the contact portion 14 in the height direction Z). This allows the protrusion 13 to be deformed more preferentially, so that the stress S on the joint W1 can be more suitably alleviated. Specifically, when the thickness t2 of the contact portion 14 is 100%, the thickness t1 of the protrusion 13 is preferably 90% or less, more preferably 85% or less, even more preferably 80% or less, and particularly preferably 75% or less. This allows the protrusion 13 to be deformed more easily by the stress S along the width direction X. On the other hand, the thickness t1 of the protrusion 13 relative to the thickness t2 of the contact portion 14 is preferably 45% or more, more preferably 50% or more, even more preferably 55% or more, and particularly preferably 60% or more. This allows the strength of the protrusion 13 to be sufficiently ensured.

[0020] The specific value of the thickness t2 of the contact portion 14 is preferably 0.1 mm or more, more preferably 0.2 mm or more, even more preferably 0.3 mm or more, and particularly preferably 0.5 mm or more. This allows the strength of the contact portion 14 to be sufficiently ensured. Meanwhile, the thickness t2 of the contact portion 14 is preferably 3.5 mm or less, more preferably 3.0 mm or less, even more preferably 2.5 mm or less, and particularly preferably 2.0 mm or less. This allows the joint portion W1 spanning the contact portion 14 and the terminal portion 144 to be easily formed.

[0021] Moreover, the height h1 of the protrusion 13 is preferably 1.0 mm or more, more preferably 1.5 mm or more, and particularly preferably 2.0 mm or more. This makes the protrusion 13 more likely to deform in response to the stress S in the planar direction, and therefore the stress S on the joint W1 can be more suitably alleviated. On the other hand, from the viewpoint of reducing the total height of the electricity storage unit 500 (see FIG. 3) when the busbar 1 is attached, the height h1 of the protrusion 13 is preferably 3.0 mm or less, and more preferably 2.0 mm or less. This can improve the loading efficiency when the electricity storage unit is mounted on an electrical product (such as an electric vehicle).

[0022] As shown in Fig. 1, the buffer section 12 in this embodiment is a recess having a substantially circular planar shape. Specifically, the buffer section 12 shown in Fig. 1 has a cylindrical protrusion 13 protruding downward D from the first base section 11. The contact section 14 shown in Fig. 1 is a disk-shaped member that closes the opening of the cylindrical protrusion 13 at the lower part D. The buffer section 12 having such a substantially circular planar shape can deform the protrusion 13 in various directions in the planar direction, and therefore can more appropriately relieve the stress S on the joint W1.

[0023] Moreover, the inner diameter d1 of the cylindrical protrusion 13 is preferably 10 mm or more, more preferably 15 mm or more, and particularly preferably 20 mm or more. This ensures a sufficient welding area, thereby increasing the reliability of the joint W1. On the other hand, from the viewpoint of reducing the size of the busbar 1 and the weight of the electricity storage device, the inner diameter d1 of the protrusion 13 is preferably 25 mm or less, and more preferably 20 mm or less.

[0024] (2)Second bonding area 20 The second joint region 20 is a region that is joined to a terminal portion 144 of a second power storage device 100B that is different from the first power storage device 100A. This second joint region 20 is formed at the other end (right side R) in the width direction X of the busbar 1. Similarly to the first joint region 10, a joint portion W2 that straddles the second joint region 20 and the terminal portion 144 is formed in a part (contact portion 24) of the second joint region 20.

[0025] In the busbar 1 according to the present embodiment, the second joint region 20 is also provided with a buffer section 22. The buffer section 22 in the second joint region 20 has a structure substantially equivalent to that of the buffer section 12 in the first joint region 10 described above. Specifically, the second joint region 20 has a plate-shaped joint base section (second base section 21). The buffer section 22 in the second joint region 20 is also configured with a step protruding from the second base section 21 toward the downward direction D. More specifically, the buffer section 22 has a protruding section 23 protruding from the second base section 21 toward the downward direction D, and a contact section 24 provided at a lower end 23a of the protruding section 23 and brought into contact with the terminal section 144. The buffer section 22 having such a configuration can suitably absorb the stress S in the planar direction, and can thus alleviate the stress S on the joint section W2 in the second joint region 20.

[0026] As described above, the buffer section 22 of the second bonding region 20 has a structure substantially equivalent to that of the buffer section 12 of the first bonding region 10. Therefore, the dimensions of each member constituting the buffer section 22 of the second bonding region 20 can be appropriately set from the same viewpoint as the buffer section 12 of the first bonding region 10 described above. Therefore, in this specification, overlapping descriptions will be omitted. However, the dimensions of each of the buffer sections 12, 22 are appropriately changed depending on the shape of the terminal section 144 to be bonded, and do not need to be completely the same. In other words, the buffer section 22 of the second bonding region 20 may have dimensions different from those of the buffer section 12 of the first bonding region 10.

[0027] (3) Crosslinked region The bridging region 30 is a region that connects the first bonding region 10 and the second bonding region 20. The bridging region 30 bridges the first bonding region 10 and the second bonding region 20, thereby electrically connecting the first electricity storage device 100A and the second electricity storage device 100B.

[0028] Moreover, the bridging region 30 in this embodiment has a fluctuation absorbing portion 32 that absorbs fluctuations in the gap G between the first joining region 10 and the second joining region 20. This can alleviate stress applied to the busbar 1 itself. Specifically, the bridging region 30 in this embodiment has a plate-shaped bridging base portion 31. The fluctuation absorbing portion 32 is configured as a step protruding from the bridging base portion 31. More specifically, the fluctuation absorbing portion 32 has a protruding portion 33 that protrudes upward U from the bridging base portion 31 and a flat-plate-shaped connecting portion 34 provided at an upper end 33a of the protruding portion 33. The fluctuation absorbing portion 32 having such a configuration can preferentially deform the protruding portion 33 when the gap G between the first joining region 10 and the second joining region 20 varies, and can therefore alleviate stress applied to the busbar 1 itself.

[0029] In addition, the thickness (dimension in the width direction X) t3 of the protruding portion 33 of the bridging region 30 is preferably smaller than the thickness (dimension in the height direction Z) t4 of the connecting portion 34. This makes the protruding portion 33 of the bridging region 30 more easily deformable. Specifically, when the thickness t4 of the connecting portion 34 is taken as 100%, the thickness t3 of the protruding portion 33 is preferably 90% or less, more preferably 85% or less, even more preferably 80% or less, and particularly preferably 75% or less. On the other hand, the ratio of the thickness t3 of the protruding portion 33 to the thickness t4 of the connecting portion 34 is preferably 50% or more, more preferably 55% or more, and particularly preferably 60% or more. This makes it possible to ensure sufficient strength of the protruding portion 33.

[0030] Specifically, the thickness t4 of the connecting portion 34 is preferably 0.1 mm or more, more preferably 0.25 mm or more, and particularly preferably 0.5 mm or more. This ensures sufficient strength of the connecting portion 34. On the other hand, the upper limit of the thickness t4 of the connecting portion 34 is preferably 3.0 mm or less, more preferably 2.5 mm or less, and particularly preferably 2.0 mm or less. This makes the bridging region 30 (the protrusion 33, the connecting portion 34) more easily deformable, and therefore the stress S applied to the first bonding region 10 and the second bonding region 20 can be reduced.

[0031] Furthermore, the height h2 of the protruding portion 33 of the bridging region 30 is preferably 1.0 mm or more, more preferably 1.5 mm or more, even more preferably 2.0 mm or more, and particularly preferably 2.5 mm or more. This makes the protruding portion 33 of the bridging region 30 more likely to deform. Meanwhile, the height h2 of the protruding portion 33 of the bridging region 30 is preferably 5.0 mm or less, more preferably 4.0 mm or less, and particularly preferably 3.0 mm or less. This makes it possible to reduce the total height of the electricity storage unit 500 (see FIG. 3), thereby improving the loading efficiency when the electricity storage unit 500 is mounted on an electrical product (such as an electric vehicle).

[0032] As shown in FIG. 1, the fluctuation absorbing portion 32 in this embodiment is a band-shaped step formed over the entire area of ​​the cross-linked region 30 in the depth direction Y. In other words, the fluctuation absorbing portion 32 has a pair of protruding portions 33 that protrude upward U from the entire area of ​​the cross-linked base portion 31 in the depth direction Y. The pair of protruding portions 33 face each other in the width direction X. A connecting portion 34, which is a substantially rectangular plate-shaped member, is provided to connect the upper ends 33a of the pair of protruding portions 33. The fluctuation absorbing portion 32 having such a configuration can sufficiently absorb large stress along the width direction X, and therefore can suppress the stress from being applied to the first bonding region 10 and the second bonding region 20.

[0033] Furthermore, the width dimension W1 of the connecting portion 34 is not particularly limited and can be appropriately adjusted in consideration of the dimensions and installation positions of the first electricity storage device 100A and the second electricity storage device 100B. For example, the lower limit of the width dimension W1 of the connecting portion 34 may be 10 mm or more, 15 mm or more, or 20 mm or more. On the other hand, the upper limit of the width dimension w1 of the connecting portion 34 may be 70 mm or less, 60 mm or less, or 50 mm or less.

[0034] The structure of the busbar 1 according to this embodiment has been described above. As described above, the busbar 1 having such a configuration includes buffer portions 12, 22 that absorb stress S caused by fluctuations in the gap G between the first joint region 10 and the second joint region 20. This makes it possible to prevent stress S from being applied to joint portions W1, W2 between the busbar 1 and the terminal portion 144.

[0035] 2. Configuration of the Energy Storage Unit Next, an energy storage unit 500 using the bus bar 1 having the above configuration will be described. FIG. 3 is a perspective view that typically shows an energy storage unit according to a first embodiment. FIG. 4 is a perspective view that typically shows an energy storage device in FIG. 3. FIG. 5 is an enlarged cross-sectional view that typically shows a structure in the vicinity of a terminal mounting hole of the energy storage device shown in FIG. 4. FIG. 6 is an enlarged cross-sectional view that typically shows a procedure for producing the insulating material in FIG. 5. FIG. 7 is an enlarged cross-sectional view that typically shows a connection structure of the energy storage unit shown in FIG. 3.

[0036] (1) Electricity storage device 100 3 includes a plurality of power storage devices 100. Specifically, flat rectangular power storage devices 100 are used in this power storage unit 500. The plurality of power storage devices 100 are arranged along the width direction X with their flat surfaces facing each other. The number of power storage devices 100 included in the power storage unit 500 is not particularly specified, and may be changed as appropriate depending on the purpose of the power storage unit 500 (such as the required power and specifications of electrical appliances to be used).

[0037] 4 and 5, the electricity storage device 100 includes an electrode body 110, a case 120, an insulating material 130, and a current collector 140. An example of the structure of the electricity storage device 100 will be described below.

[0038] (1-1) Electrode body 110 The electrode body 110 is a power generating element of the power storage device 100. The power storage device 100 shown in FIG. 5 includes one electrode body 110. However, the number of electrode bodies is not particularly limited and may be more than one. Although detailed illustration is omitted, the electrode body 110 includes a positive electrode plate, a negative electrode plate, and a separator. The positive electrode plate includes a positive electrode core body that is a conductive metal foil (such as aluminum foil) and a positive electrode active material layer applied to the surface of the positive electrode core body. On the other hand, the negative electrode plate includes a negative electrode core body that is a conductive metal foil (such as copper foil) and a negative electrode active material layer applied to the surface of the negative electrode core body. The separator is an insulating sheet interposed between the positive electrode plate and the negative electrode plate. Note that the materials of each member (positive electrode plate, negative electrode plate, separator, etc.) constituting the electrode body 110 can be materials that can be used in general power storage devices without particular restrictions, and detailed explanations are omitted because they do not limit the technology disclosed herein.

[0039] The specific structure of the electrode body 110 is not particularly limited. For example, the electrode body 110 may be a wound electrode body in which a laminate including a positive electrode plate, a negative electrode plate, and a separator is wound. The electrode body 110 may be a laminated electrode body in which a plurality of positive electrode plates, a plurality of negative electrode plates, and a plurality of separators are laminated. However, regardless of which structure is adopted, connection tabs 112 are formed on both side edges of the electrode body 110 in the depth direction Y. One of the connection tabs 112 is a positive electrode tab electrically connected to the positive electrode plate. This positive electrode tab is formed, for example, by bundling positive electrode core bodies on which a positive electrode active material layer is not applied. The other connection tab 112 is a negative electrode tab electrically connected to the negative electrode plate. This negative electrode tab is formed by bundling negative electrode core bodies on which a negative electrode active material layer is not applied. As will be described in detail later, these connection tabs 112 are electrically connected to the current collector 140.

[0040] (1-2) Case 120 The case 120 is a container that houses the electrode body 110 and has a terminal mounting hole 125. Specifically, the case 120 is a flat box-shaped container having an internal space. The electrode body 110 is housed in the internal space of the case 120. Although not shown in the drawings, an electrolyte is also housed inside the case 120. The electrolyte can be any electrolyte that can be used in a general electricity storage device without any particular restrictions, and detailed description thereof will be omitted as it does not limit the technology disclosed herein.

[0041] The case 120 also includes a case body 122 and a sealing plate 124. The case body 122 is a box-shaped body having an upper opening. As shown in FIG. 4, the case body 122 includes a bottom 122b that is a long rectangular plate-shaped member, a pair of first side walls 122c that extend upward D from a long side (side along the depth direction Y) of the bottom 122b, and a pair of second side walls 122d that extend upward D from a short side (side along the width direction X) of the bottom 122b. An upper opening surrounded by the upper ends of the first side wall 122c and the second side wall 122d is formed on the upper surface of the case body 122. On the other hand, the sealing plate 124 is a rectangular plate-shaped member that closes the upper opening of the case body 122. Specifically, as shown in FIG. 5, the sealing plate 124 is fitted into the upper opening of the case body 122. The boundary between case body 122 and sealing plate 124 is joined by laser welding or the like. Case 120 (case body 122 and sealing plate 124) is preferably a metal member having a certain level of strength or higher. Examples of materials for case 120 include metal materials such as aluminum and aluminum alloys.

[0042] As described above, the case 120 is formed with a terminal mounting hole 125. The terminal mounting hole 125 is a through hole penetrating the case 120. The terminal mounting hole 125 is an opening for forming a conductive path from the electrode body 110 inside the case 120 to the outside of the case 120. As shown in FIG. 4, the terminal mounting hole 125 is a circular opening in a plan view. However, the planar shape of the terminal mounting hole is not particularly limited and may be rectangular. In addition, in the power storage device 100 shown in FIG. 4, two terminal mounting holes 125 are formed in the sealing plate 124 of the case 120. Specifically, the terminal mounting holes 125 are formed at both ends of the sealing plate 124 in the depth direction Y. One of the terminal mounting holes 125 is a positive electrode terminal mounting hole 125P that forms a conductive path with the positive electrode of the electrode body 110. Moreover, the other terminal mounting hole 125 becomes a negative electrode terminal mounting hole 125N that forms a conductive path with the negative electrode of the electrode body 110. In the following, the structure around the negative electrode terminal mounting hole 125N will be described as an example.

[0043] (1-3) Insulation material 130 The insulating material 130 covers the peripheral wall 125a of the terminal mounting hole 125 and the peripheral parts 120a1 and 120b1 of the terminal mounting hole 125 continuously in the circumferential direction, and is joined to the peripheral parts 120a1 and 120b1 of the terminal mounting hole 125. This insulating material 130 is a member for preventing conduction to the case 120. Specifically, a current collector 140 that forms a conductive path from the electrode body 110 to the outside of the case 120 is attached inside the case 120. In addition, as shown in FIG. 3, a bus bar 1 is attached to the outside of the case 120. Conduction to the case 120 can be prevented by interposing the insulating material 130 between these conductive members and the case 120. The insulating material 130 is made of insulating resin such as polypropylene resin, polyphenylene sulfide resin, polyamide resin, polyacetal resin, and polyimide resin. Moreover, the insulating material 130 has an opening 138 penetrating the insulating material 130. The insulating material 130 is formed so that the opening 138 and the terminal mounting hole 125 overlap. In other words, the insulating material 130 is disposed so as not to block the terminal mounting hole 125 of the case 120.

[0044] The insulating material 130 shown in FIG. 5 is produced by insert molding. In this insert molding, first, as shown in FIG. 6, the current collector 140 and the mold M are attached to the sealing plate 124. At this time, the positional relationship of each member is adjusted so that a cavity S1 having a shape corresponding to the insulating material 130 to be produced is generated. Next, a resin material is filled into the inside of the cavity S1 through the injection hole M1 of the mold M. Then, the resin material is hardened to produce the insulating material 130 having a shape corresponding to the cavity S1. When the insulating material 130 is produced by insert molding in this manner, the sealing plate 124 and the current collector 140 are integrated through the insulating material 130. As a result, the insulating material 130 covers the peripheral wall 125a of the terminal mounting hole 125 and the peripheral parts 120a1 and 120b1 of the terminal mounting hole 125 continuously in the circumferential direction, and is joined to the peripheral parts 120a1 and 120b1 of the terminal mounting hole 125. After insert molding, the insulating material 130 has an outer insulating portion 132, an inner insulating portion 134, and an inner-hole insulating portion 136. The specific shape of each portion will be described below.

[0045] The insulating material 130 includes an external insulating portion 132 joined to a peripheral portion 120a1 of the terminal mounting hole 125 in the outer surface 120a of the case 120. The external insulating portion 132 is a member that prevents electrical conduction between the bus bar 1 and the case 120. Specifically, the external insulating portion 132 is a plate-shaped portion that is arranged along the outer surface 120a of the case 120 (the upper surface 124a of the sealing plate 124). The lower surface 132a of the external insulating portion 132 is joined to the outer surface 120a of the case 120 by insert molding. As shown in FIG. 7, the provision of the external insulating portion 132 can prevent the bus bar 1 from contacting the case 120 (the sealing plate 124). The thickness of the external insulating portion 132 is preferably 0.5 mm or more, more preferably 1.0 mm or more, and particularly preferably 2.0 mm or more. This can more suitably prevent electrical conduction between the bus bar 1 and the case 120. On the other hand, the thickness of the external insulating part 132 is preferably 4.0 mm or less, and more preferably 3.0 mm or less, which allows the height dimension of the electricity storage device 100 to be further reduced, thereby further improving the loading efficiency of the electricity storage device in an electrical product.

[0046] The insulating material 130 also includes an internal insulating portion 134 joined to a peripheral portion 120b1 of the terminal mounting hole 125 on the inner surface 120b of the case 120. The internal insulating portion 134 is a member that prevents electrical conduction between the current collector 140 (described later) and the case 120. Specifically, the internal insulating portion 134 is a plate-shaped portion that is interposed between the inner surface 120b of the case 120 (the lower surface 124b of the sealing plate 124) and the joint portion 142 of the current collector 140. The upper surface 134a of the internal insulating portion 134 is joined to the inner surface 120b of the case 120 by insert molding. The thickness of the internal insulating portion 134 is preferably 0.1 mm or more, more preferably 0.3 mm or more, and particularly preferably 0.5 mm or more. This makes it possible to more suitably prevent electrical conduction between the current collector 140 and the sealing plate 124. On the other hand, the thickness of the internal insulating portion 134 is preferably 2.0 mm or less, and more preferably 1.0 mm or less. This increases the space for accommodating the electrode assembly 110 within the case 120, which can contribute to improving the performance of the electricity storage device 100.

[0047] The insulating material 130 includes an in-hole insulating portion 136 joined to the peripheral wall 125a of the terminal mounting hole 125. As will be described in detail later, in the power storage unit 500, the buffer portions 12, 22 of the busbar 1 are inserted into the terminal mounting hole 125, and the contact portions 14, 24 of the busbar 1 are joined to the terminal portion 144. The in-hole insulating portion 136 prevents the buffer portions 12, 22 inserted into the terminal mounting hole 125 from directly contacting the case 120 (sealing plate 124). Specifically, the in-hole insulating portion 136 is a cylindrical portion extending along the height direction Z. The in-hole insulating portion 136 is disposed inside the terminal mounting hole 125 of the case 120. The outer periphery 136a of the in-hole insulating portion 136 is joined to the peripheral wall 125a of the terminal mounting hole 125. In addition, in this insulating material 130, the external insulating part 132 and the internal insulating part 134 are continuous via the internal insulating part 136. In other words, the external insulating part 132, the internal insulating part 134, and the internal insulating part 136 are integrally molded. The thickness of the internal insulating part 136 is preferably 0.5 mm or more, more preferably 1.0 mm or more, and particularly preferably 2.0 mm or more. This can prevent the internal insulating part 136 from being damaged by friction or heat when inserting the buffer parts 12 and 22. On the other hand, the thickness of the internal insulating part 136 is preferably 4.0 mm or less, and more preferably 3.0 mm or less. This can ensure a sufficient size of the terminal mounting hole 125, making it easy to insert the buffer parts 12 and 22.

[0048] Moreover, the insulating material 130 has a protruding portion 134c that protrudes downward D from a part of the internal insulating portion 134 (the inner portion in the depth direction Y). This can regulate the vertical movement of the electrode body 110 in the case 120. As a result, it is possible to prevent the electrode body 110 from contacting the sealing plate 124 and the connection tab 112 from being damaged. The thickness (protruding amount) of the protruding portion 134c is preferably 2.0 mm or more, and more preferably 3.0 mm or more. This can more suitably regulate the vertical movement of the electrode body 110. Meanwhile, the thickness of the protruding portion 134c is preferably 5.0 mm or less, and more preferably 4.0 mm or less. This can ensure a sufficient storage space for the electrode body 110 in the case 120.

[0049] Although not shown, it is preferable that the surfaces of the metal members (sealing plate 124, current collector 140) that come into contact with the insulating material 130 are roughened. Specifically, the parts that are roughened are the peripheral portion 120a1 of the terminal mounting hole 125 on the outer surface 120a of the case 120, the peripheral portion 120b1 of the terminal mounting hole 125 on the inner surface 120b of the case 120, the peripheral wall 125a of the terminal mounting hole 125, and the surface of the current collector 140 that is joined to the insulating material 130 (the upper surface 142a of the joint portion 142). This allows the resin material to penetrate into the unevenness of the surfaces of each metal member when insert molding is performed. As a result, an anchor effect is generated, and the insulating material 130 and the metal member can be joined more firmly. Note that the roughening may be applied to at least one of the above-mentioned surfaces. Even in this case, the joining strength between the insulating material 130 and the metal member can be suitably improved. Furthermore, this surface roughening does not limit the technology disclosed herein. That is, even if the surface roughening is not performed, the insulating material 130 and the metal member can be sufficiently integrated by insert molding.

[0050] (1-4) Current collector 140 The current collector 140 is a conductive member electrically connected to the electrode body 110 inside the case 120. Specifically, the current collector 140 includes an internal current collecting portion 146 extending along the height direction Z. This internal current collecting portion 146 is a plate-shaped portion connected to the connection tab 112 of the electrode body 110. The internal current collecting portion 146 is preferably made of the same metal material as the connection tab 112 to be connected. For example, as described above, the negative electrode tab is made of a negative electrode core body that is copper foil. In this case, the internal current collecting portion 146 is preferably made of a copper-based material (copper, copper alloy, etc.). This allows the current collector 140 and the electrode body 110 to be connected firmly with low resistance.

[0051] Moreover, current collector 140 is disposed so as to cover terminal mounting hole 125 via insulating material 130, and is joined to insulating material 130. Current collector 140 has a terminal portion 144 that is exposed to the outside of case 120 through terminal mounting hole 125 and can be electrically connected to bus bar 1. A current collector having such a configuration will be specifically described below.

[0052] First, the current collector 140 includes a joint portion 142 which is a plate-like member joined to the insulating material 130. The joint portion 142 is joined to the lower surface 134b of the internal insulating portion 134 so as to close the terminal mounting hole 125 inside the case 120. More specifically, the joint portion 142 is formed by bending the upper end of the internal current collecting portion 146 so as to face the sealing plate 124. As a result, the joint portion 142 faces the inner surface 120b of the case 120 with the internal insulating portion 134 sandwiched therebetween. Then, the upper surface 142a of the joint portion 142 is joined to the lower surface 134b of the internal insulating portion 134 by insert molding. As a result, the lower end of the terminal mounting hole 125 is closed by the joint portion 142.

[0053] The terminal portion 144 is exposed to the outside of the case 120 through the terminal mounting hole 125. This allows the busbar 1 and the terminal portion 144 to be electrically connected. Specifically, in the structure shown in FIG. 5, the upper end of the terminal mounting hole 125 is open. As a result, a part of the current collector 140 (terminal portion 144) is exposed to the outside of the case 120. This allows the buffer portions 12, 22 of the busbar 1 to be inserted into the terminal mounting hole 125 from the outside of the case 120 (see FIG. 7). Then, a joining process such as laser welding is performed with the contact portions 14, 24 of the busbar 1 in contact with the terminal portion 144. This forms joint portions W1, W2 that straddle the contact portions 14, 24 and the terminal portion 144, allowing the busbar 1 and the current collector 140 to be electrically connected.

[0054] Also, the terminal portion 144 of the electricity storage device 100 shown in FIG. 5 is located inward from the outer surface 120a of the case 120. In other words, as shown in FIG. 5, the upper surface 144a of the terminal portion 144 is located on the lower D side from the outline L1 along the outer surface 120a of the case 120. This can prevent a part of the current collector 140 from protruding outside the case 120. In addition, in this electricity storage device 100, the terminal mounting hole 125 is sealed by the insulating material 130 and the current collector 140 (the joint portion 142 and the terminal portion 144). This can prevent the electrolyte from leaking out and foreign matter from entering. As described above, according to the electricity storage device 100 having the configuration shown in FIG. 5, it is possible to form a conductive path to the outside of the case 120 and to seal the inside of the case 120 without providing an external connection portion. That is, according to the configuration shown in FIG. 5, it is possible to eliminate the conductive member protruding outside the case 120, and therefore it is possible to reduce the height dimension of the electricity storage device 100. As a result, the loading efficiency of the electricity storage device 100 in the electrical appliance can be improved.

[0055] The terminal portion 144 shown in FIG. 5 is a convex terminal portion inserted into the terminal mounting hole 125 from the inside of the case 120. This raises the position of the upper surface 144a of the terminal portion 144 in the terminal mounting hole 125, facilitating the connection between the terminal portion 144 and the busbar 1 (i.e., the insertion of the buffer portions 12, 22 from above U). Furthermore, when the convex terminal portion 144 is inserted from the lower portion D of the terminal mounting hole 125, the movement of the current collector 140 in the horizontal direction (depth direction Y and width direction X) is restricted. This also makes it possible to suppress peeling of the bonding interface between the joint portion 142 and the internal insulating portion 134. Note that as the position of the upper surface 144a of the terminal portion 144 in the terminal mounting hole 125 is raised, the connection between the terminal portion 144 and the busbar 1 tends to become easier. From this viewpoint, distance H3 from outer surface 120a of case 120 to upper surface 144a of terminal portion 144 is preferably 2.0 mm or less, more preferably 1.0 mm or less, and even more preferably 0.5 mm or less. Upper surface 144a of terminal portion 144 may be at substantially the same height as outer surface 120a of case 120 (i.e., distance H3 is 0 mm). In this case, connection between terminal portion 144 and bus bar 1 becomes even easier.

[0056] As described above, the current collector 140 shown in FIG. 5 includes the joint 142, which is a plate-like member joined to the insulating material 130. In this case, the convex terminal portion 144 shown in FIG. 5 is a columnar member joined to the upper surface 142a of the joint 142. This ensures a sufficient thickness for the terminal portion 144. As a result, a suitable welding depth can be ensured when forming the joints W1 and W2. Furthermore, when such a configuration is adopted, the material of the terminal portion 144 can be freely selected without being affected by the materials of the other portions (the joint 142, the internal current collecting portion 146).

[0057] For example, as shown in FIG. 5, a clad material having a first layer 147 and a second layer 145 can be used as the terminal portion 144. The first layer 147 of the terminal portion 144 is joined to the upper surface 142a of the joint portion 142, and is a layer made of the same type of metal as the joint portion 142. This allows the terminal portion 144 and the joint portion 142 to be firmly joined. On the other hand, the second layer 145 is exposed to the outside of the case 120 through the terminal mounting hole 125, and is a layer made of a metal different from that of the first layer 147. This allows a metal that is easy to connect to the bus bar 1 to be disposed on the upper surface 144a of the terminal portion 144. For example, in the negative electrode side current collector 140, a copper-based material is used for the internal current collector 146 and the joint portion 142 in consideration of the connectivity with the negative electrode tab. On the other hand, in the positive electrode side current collector, an aluminum-based material is used in consideration of the connectivity with the positive electrode tab. At this time, the busbar 1 connecting the positive electrode side current collector and the negative electrode side current collector is often made of an aluminum-based material in consideration of the connectivity with the positive electrode side terminal portion 144. In this case, it is preferable that the negative electrode side current collector 140 has a first layer 147 of the terminal portion 144 made of copper and a second layer 145 made of aluminum. This makes it possible to form a copper-copper bonding interface between the terminal portion 144 and the joint portion 142, and also to form an aluminum-copper bonding interface between the terminal portion 144 and the busbar 1. As a result, a conductive path from the electrode body 110 to the busbar 1 can be formed with a strong and low resistance.

[0058] An example of the power storage device 100 used in the power storage unit 500 has been described above. As described above, the power storage device 100 having the configuration shown in FIG. 5 does not have a conductive member (terminal portion 144) protruding outside the case 120, and therefore the height dimension is reduced. This can improve the loading efficiency of the power storage device 100 in an electrical product. Note that in the power storage unit 500 according to this embodiment, all of the multiple power storage devices 100 do not need to have the above configuration. For example, when mounting the power storage unit in an electrical product, only some of the multiple power storage devices interfere with other components, and therefore it may be necessary to reduce the height dimension of the entire power storage unit. In such a case, it is advisable to adopt the above configuration only for the power storage device that interferes with other components. This can improve the loading efficiency of the power storage device.

[0059] (2) Restraint member Next, the energy storage unit 500 shown in Fig. 3 includes a restraining member that restrains a plurality of energy storage devices 100. Specifically, a pair of end plates 220 are arranged on both outer sides in the arrangement direction (width direction X) of the energy storage units 500. The pair of end plates 220 are bridged by a restraining beam member 230. This allows a restraining pressure along the arrangement direction to be applied to each of the energy storage devices 100. In addition, a resin buffer member 250 is arranged between each of the arranged energy storage devices 100. This allows the restraining pressure applied to the energy storage devices 100 to be uniform.

[0060] (3) Busbar The energy storage unit 500 according to this embodiment uses the bus bar 1 having the above-described configuration. This bus bar 1 electrically connects a plurality of energy storage devices 100. Specifically, in the energy storage unit 500 shown in Fig. 3, the plurality of energy storage devices 100 are arranged such that the positive electrode terminal mounting hole 125P of one energy storage device 100 and the negative electrode terminal mounting hole 125N of the other energy storage device 100 are adjacent to each other. The bus bar 1 is connected to the terminal portions 144 present inside each of a pair of adjacent terminal mounting holes 125.

[0061] Here, the busbar 1 in this embodiment has stepped buffer sections 12, 22 that protrude downward D (see FIGS. 1 and 2). As described above, these buffer sections 12, 22 are inserted into the terminal mounting holes 125 from the outside of the case 120. Then, the contact sections 14, 24, which are the bottom surfaces of the buffer sections 12, 22, are joined to the terminal section 144. This allows the terminal section 144 to be easily connected to the busbar 1 even when the terminal section 144 is disposed inward (downward D) from the outer surface 120a of the case 120.

[0062] When the buffer parts 12, 22 are inserted into the terminal mounting hole 125, it is preferable to set the inner dimensions of the terminal mounting hole 125 and the outer dimensions of the buffer parts 12, 22 to be approximately equal. This brings the outer peripheral walls of the protrusions 13, 23 into contact with the inner peripheral wall of the in-hole insulating part 136, so that movement (vibration, etc.) of the contact parts 14, 24 in the planar direction can be restricted. As a result, it is possible to more suitably prevent the stress S in the planar direction from being applied to the joint parts W1, W2 between the contact parts 14, 24 and the terminal part 144.

[0063] <Other embodiments> One embodiment of the technology disclosed herein has been described above. However, the technology disclosed herein is not limited to the above-described embodiment. Other embodiments of the technology disclosed herein will be described below.

[0064] 1. Buffer section with groove As shown in FIG. 2, the buffer parts 12, 22 in the first embodiment include contact parts 14, 24 with flat upper surfaces. However, as shown in FIG. 8, groove parts 14a, 24a may be formed on the upper surfaces of the contact parts 14, 24. The groove parts 14a, 24a are annular groove parts in a plan view. The parts where the groove parts 14a, 24a are formed are thinner than other areas, so that the joint parts W1, W2 penetrating the contact parts 14, 24 can be easily formed. Furthermore, when the groove parts 14a, 24a are formed, the joint parts W1, W2 can be easily formed even if other parts are made thick. This can also contribute to improving the overall strength of the busbar 1.

[0065] 2. Planar shape of the buffer section As shown in FIG. 1, in the first embodiment, the buffer parts 12 and 22 are provided with a planar shape that is substantially circular. However, the planar shape of the buffer parts is not particularly limited, and various shapes can be adopted. For example, as shown in FIG. 9, the busbar 1 may include the buffer parts 12 and 22 with a planar shape that is substantially rectangular. Even in this case, the stress along each of the width direction X and the depth direction Y can be appropriately alleviated. Moreover, as shown in FIG. 10, the busbar 1 may include the band-shaped buffer parts 12 and 22 that extend over the entire depth direction Y in a plan view. Even in this case, the stress along the width direction X can be alleviated. As described above, the stress S caused by the variation in the interval G between the first joining region 10 and the second joining region 20 is mainly a stress along the width direction X, so that the band-shaped buffer parts 12 and 22 shown in FIG. 10 can be sufficiently alleviated.

[0066] 3. Buffer sections other than those with step shapes In the above-described embodiments, the step-shaped buffer sections 12, 22 each including the protruding portion 13, 23 and the contact portion 14, 24 are formed (see FIGS. 1, 9, and 10). However, the buffer section is not limited to the step-shaped buffer section as long as it can absorb the stress caused by the variation in the distance between the first and second bonding regions. For example, the busbar 1 shown in FIG. 11 has a pair of openings 17, 27 extending in the depth direction Y. In this busbar 1, the bonding portions W1, W2 are formed between the pair of openings 17, 27. In the busbar 1 having such a configuration, when a stress S occurs along the width direction X, the busbar 1 is deformed so that the openings 17, 27 are crushed. This allows the stress S along the width direction X to be sufficiently absorbed. In other words, the buffer section in the busbar disclosed herein is not limited to the step-shaped buffer section described above, and may be formed of the openings 17, 27 as shown in FIG. 11.

[0067] 4. Number of bonding areas with buffers As shown in FIG. 1 and FIG. 2, in the busbar 1 according to the first embodiment, the buffer portions 12, 22 are provided in both the first joining region 10 and the second joining region 20. However, the buffer portions may be formed in only one of the first joining region and the second joining region. Even in this case, it is possible to prevent a large stress from being applied to the joining region where the buffer portions are formed. In particular, as shown in FIG. 3, the terminal portions 144 of the power storage devices 100 arranged at both ends in the arrangement direction (width direction X) are not connected to the adjacent power storage devices 100. Then, the open terminal portions 144 are connected to an external device (such as a motor) as a total positive terminal (or a total negative terminal). The busbar used for this connection portion only needs to have the buffer portions formed in the joining region that is joined to the total positive terminal (or the total negative terminal). This makes it possible to suppress the application of stress to the joining portion between the terminal portions and the busbar.

[0068] 5.Structure of the cross-linked region Furthermore, the busbar 1 according to the first embodiment has a fluctuation absorbing portion 32 provided in the bridging region 30 (see FIGS. 1 and 2). However, the busbar disclosed herein does not necessarily have to have a fluctuation absorbing portion provided in the bridging region. As described above, if the buffer portions 12, 22 are provided in at least one of the first joint region 10 and the second joint region 20, the stress on the joints W1, W2 between the terminal portion 144 and the busbar 1 can be reduced.

[0069] 6. Terminal structure of electricity storage device As described above, the power storage unit disclosed herein is not limited to the form in which the power storage device 100 shown in FIG. 4 and FIG. 5 is used. In particular, even if the structure shown in FIG. 4 and FIG. 5 is not adopted, the terminal portion can be arranged inside the case to improve the loading efficiency of the power storage device. For example, the terminal portion 144 of the power storage device 100 having the structure shown in FIG. 5 is a columnar clad material having a first layer 147 and a second layer 145. However, the terminal portion 144 is not limited to a columnar clad material. For example, the terminal portion 144 may be a columnar member made of a single metal material (see FIG. 12). Even if such a configuration is adopted, the loading efficiency of the power storage device 100 can be improved by arranging the upper surface 144a of the terminal portion 144 inside (lower D) than the outer surface 120a of the case 120.

[0070] Terminal portion 144 made of a single metal material can be particularly suitably used when joint portion 142 and bus bar 1 are made of the same material. For example, in the positive electrode side current collector 140, an aluminum-based material is used for internal current collecting portion 146 and joint portion 142 in consideration of connectivity with the positive electrode tab (aluminum foil). On the other hand, as described above, an aluminum-based material is also used for bus bar 1 when constructing power storage unit 500. In such a configuration, even if a clad material is not used for terminal portion 144, a conductive path from electrode body 110 to bus bar 1 can be constructed of an aluminum-based material, and therefore a strong, low-resistance conductive path can be formed.

[0071] In the first embodiment, the columnar terminal portion 144 is joined to the upper surface 142a of the joint portion 142 (see FIG. 5). However, the convex terminal portion 144 is not limited to this configuration. For example, when the joint portion 142 of the current collector 140 is a plate-shaped member, the convex terminal portion 144 can be formed by bending the joint portion 142 (see FIG. 13). This convex terminal portion 144 can be formed by performing a press process on the plate-shaped joint portion 142. Even when the terminal portion 144 having such a configuration is inserted into the terminal mounting hole 125, the connection between the terminal portion 144 and the bus bar 1 is facilitated, and the movement of the current collector 140 in the horizontal direction can be restricted. In addition, according to the present embodiment, the number of parts of the current collector 140 can be reduced, which contributes to reducing material costs.

[0072] In the first embodiment, the convex terminal portion 144 is inserted into the terminal mounting hole 125. However, the current collector of the electricity storage device does not have to have a convex terminal portion. For example, as shown in FIG. 14, the joint portion 142 and the terminal portion 144 may form a continuous flat surface. Even when such a configuration is adopted, the terminal mounting hole 125 can be sealed by the insulating material 130 and the terminal portion 144. Even when such a configuration is adopted, the terminal portion 144 is exposed to the outside of the case 120 through the terminal mounting hole 125, so that the bus bar 1 and the current collector 140 can be electrically connected. Also in this case, the terminal portion 144 is disposed inward (downward D) from the outer surface 120a of the case 120, so that the loading efficiency of the electricity storage device in the electrical product can be improved.

[0073] In addition, the energy storage unit 500 according to the first embodiment uses an energy storage device 100 in which a terminal portion 144 is disposed inside a case 120. In the first embodiment, the buffer portions 12 and 22 of the busbar 1 are inserted into the terminal mounting hole 125. However, the structure of the busbar disclosed herein is not influenced by the structure of the terminal portion of the energy storage device. In other words, the structure of the energy storage device 100 does not limit the technology disclosed herein. For example, as shown in FIG. 15, even when an energy storage device 100 having a terminal portion 144 protruding outside the case 120 is used, the buffer portions 12 and 22 of the busbar 1 and the terminal portion 144 can be appropriately joined. Even when such a configuration is adopted, the buffer portions 12 and 22 of the busbar 1 can absorb stress along the width direction X, and therefore stress on the joint portions W1 and W2 can be alleviated.

[0074] In the first embodiment, the outer walls of the protruding portions 13, 23 of the busbar 1 are in contact with the inner walls of the hole-inside insulating portion 136 of the insulating material 130 (see FIG. 7). This restricts the movement of the contact portions 14, 24 in the planar direction, and therefore the application of stress to the joint portions W1, W2 can be more suitably suppressed. However, the means for restricting the movement of the contact portions 14, 24 in the planar direction is not limited to the above-mentioned structure. For example, as shown in FIG. 16, when using an electricity storage device 100 having a terminal portion 144 protruding outside the case 120, a movement restricting portion 144a protruding upward U may be provided on the outer periphery of the terminal portion 144. Then, the busbar 1 and the terminal portion 144 are joined so that the outer walls of the protruding portions 13, 23 of the busbar 1 are in contact with the movement restricting portion 144a. This allows the movement of the contact portions 14, 24 in the planar direction to be appropriately restricted. That is, in order to restrict the movement of contact portions 14, 24 in the planar direction, outer walls of protrusions 13, 23 of busbar 1 may be brought into contact with parts of electricity accumulation device 500.

[0075] The technology disclosed herein has been described in detail above. However, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes to the specific examples exemplified above. In other words, the technology disclosed herein includes the embodiments described in items 1 to 9 below.

[0076] [Item 1] a first bonding region to be bonded to a terminal portion of the first power storage device; a second joining region joined to a terminal portion of a second power storage device different from the first power storage device; a bridging region connecting the first bonding region and the second bonding region; having A busbar, wherein at least one of the first joint region and the second joint region is provided with a buffer portion that absorbs stress caused by fluctuations in the distance between the first joint region and the second joint region.

[0077] [Item 2] At least one of the first bonding region and the second bonding region has a plate-shaped bonding base portion; 2. The busbar according to claim 1, wherein the buffer portion is configured with a step protruding from the joint base portion.

[0078] [Item 3] The buffer section is a protrusion protruding from the joint base; a contact portion provided at a tip of the protruding portion and adapted to come into contact with the terminal portion; 3. The busbar according to item 2, comprising:

[0079] [Item 4] Item 4. The busbar according to item 3, wherein a thickness of the protrusion portion is smaller than a thickness of the contact portion.

[0080] [Item 5] 5. The bus bar according to claim 4, wherein the thickness of the protruding portion is 50% to 90% of the thickness of the contact portion, which is taken as 100%.

[0081] [Item 6] 6. The bus bar according to claim 1, wherein the buffer portion is provided in both the first joint region and the second joint region.

[0082] [Item 7] 7. The busbar according to any one of items 1 to 6, wherein the bridging region has a fluctuation absorbing portion that absorbs fluctuations in the gap between the first joint region and the second joint region.

[0083] [Item 8] The bridging region has a plate-shaped base portion, 8. The bus bar according to item 7, wherein the fluctuation absorbing portion is configured with a step.

[0084] [Item 9] A plurality of power storage devices; a plurality of bus bars electrically connecting terminal portions of the plurality of power storage devices; Equipped with An electricity storage unit, wherein at least one of the plurality of bus bars is the bus bar according to any one of items 1 to 8.

[0085] [Item 10] At least one of the plurality of power storage devices is An electrode body; a case that houses the electrode body and has a terminal mounting hole; an insulating material that covers a peripheral wall and a peripheral edge portion of the terminal mounting hole continuously in a circumferential direction and is joined to the peripheral edge portion of the terminal mounting hole; a current collector electrically connected to the electrode body inside the case; Equipped with The current collector is The insulating material is disposed so as to close the terminal mounting hole, bonded to the insulating material; a terminal portion exposed to the outside of the case through the terminal mounting hole and electrically connectable to the bus bar; the terminal portion is located inward from an outer surface of the case, and the terminal mounting hole is sealed by the insulating material and the current collector; 10. The energy storage unit according to item 9, wherein the buffer portion of the bus bar is inserted into the terminal mounting hole from an external side of the case and connected to the terminal portion. [Explanation of symbols]

[0086] 1 Busbar 10 1st joint area 11 First base part 12 Buffer section 13 Protrusion 14 Contact part 17 Opening 20 Second joint area 21 Second base part 22 Buffer section 23 Protrusion 24 Contact part 30 Crosslinked area 31 Bridge base part 32 Fluctuation absorber 33 Protrusion 34 Connecting part 100 Energy storage device 110 Electrode body 120 cases 122 Case body 124 Sealing plate 125 Terminal mounting hole 130 Insulation Materials 140 Current collector 142 Joint 144 Terminal section 500 Energy Storage Unit

Claims

1. a first bonding region to be bonded to a terminal portion of the first power storage device; a second bonding region that is bonded to a terminal portion of a second power storage device different from the first power storage device; a bridging region connecting the first bonding region and the second bonding region; having A bus bar, comprising: a buffer portion provided in at least one of the first and second bonding regions, the buffer portion absorbing stress caused by fluctuations in the distance between the first and second bonding regions.

2. At least one of the first bonding region and the second bonding region has a plate-shaped bonding base portion; The busbar according to claim 1 , wherein the buffer portion is configured as a step protruding from the joint base portion.

3. The buffer section is a protrusion protruding from the joint base; a contact portion provided at a tip of the protruding portion and adapted to come into contact with the terminal portion; The busbar of claim 2 , further comprising:

4. The bus bar according to claim 3 , wherein a thickness of the protruding portion is smaller than a thickness of the contact portion.

5. 5. The bus bar according to claim 4, wherein a thickness of the protruding portion is 50% to 90% of a thickness of the contact portion that is 100%.

6. The bus bar according to claim 1 , wherein the buffer portion is provided in both the first joint region and the second joint region.

7. The bus bar according to claim 1 , wherein the bridging region has a fluctuation absorbing portion that absorbs fluctuations in the distance between the first bonding region and the second bonding region.

8. The bridging region has a plate-shaped bridging base portion, The bus bar according to claim 7 , wherein the fluctuation absorbing portion is configured as a step protruding from the bridge base portion.

9. A plurality of power storage devices; a plurality of bus bars electrically connecting terminal portions of the plurality of power storage devices; Equipped with The power storage unit, wherein at least one of the plurality of bus bars is the bus bar according to any one of claims 1 to 8.

10. At least one of the plurality of power storage devices is An electrode body; a case that houses the electrode body and has a terminal mounting hole; an insulating material that covers a peripheral wall and a peripheral edge portion of the terminal mounting hole continuously in a circumferential direction and is joined to the peripheral edge portion of the terminal mounting hole; a current collector electrically connected to the electrode body inside the case; Equipped with The current collector is The insulating material is disposed so as to close the terminal mounting hole, bonded to the insulating material; a terminal portion exposed to the outside of the case through the terminal mounting hole and electrically connectable to the bus bar; the terminal portion is located inward from an outer surface of the case, and the terminal mounting hole is sealed by the insulating material and the current collector; The energy storage unit according to claim 9 , wherein the buffer portion of the bus bar is inserted into the terminal mounting hole from an external side of the case and joined to the terminal portion.

Images