Battery pack

Abstract

The present invention relates to a battery pack using bus bars, and is characterized in that, in a bus bar connecting a first positive terminal of a first adjacent battery and a second negative terminal of a second adjacent battery, a first conducting member of the bus bar has a first joint portion engaged with the first positive terminal and a first extension portion extending from the first joint portion, a second conducting member of the bus bar has a second joint portion engaged with the second negative terminal and a second extension portion extending from the second joint portion, the first conducting member and the second conducting member are made of different materials from each other and are connected at a third joint portion, the third joint portion is formed at an overlapping portion of the first extension portion and the second extension portion, and one of a distance from the first joint portion and a distance from the second joint portion is closer than the other.

Description

Technical Field

[0001] This invention relates to busbars for battery packs and battery packs. Background Technology

[0002] In battery packs containing multiple lithium-ion batteries or other secondary batteries, metal connecting components called busbars are used to connect the positive and negative electrodes of adjacent secondary batteries. Busbars are flat plate-shaped components made of metals such as aluminum, copper, or iron, and are joined to the positive and negative electrodes of the secondary batteries by laser welding, ultrasonic welding, or other fasteners.

[0003] Sometimes, vibrations during assembly or handling can cause the relative distances between individual cells in a battery pack to become undesirable. Furthermore, the relative distances between cells can change due to energization and the expansion and contraction of the cells. Therefore, stress may be generated in the busbars or the positive / negative electrodes of the cells, leading to fatigue failure.

[0004] To alleviate stress generated in busbars or secondary batteries, one known method is to form a stress-relieving section protruding into a U-shape by stamping a flat plate perpendicular to its thickness direction at the middle of the busbar's length. In this configuration, when the busbar undergoes thermal expansion, the stress-relieving section deforms, thereby reducing the load transmitted to the positive and negative electrodes of the secondary battery. Alternatively, in such configurations, the U-shaped stress-relieving section can be formed as a twisted section twisted approximately 90° relative to the thickness direction of the flat plate (see, for example, Patent Document 1). However, this method has almost no effect on stress relief for loads applied perpendicular to the thickness direction. Even when the stress-relieving section is formed as a twisted section twisted approximately 90° relative to the thickness direction of the flat plate, the high rigidity of the twisted section means that, essentially the same as with busbars without a twisted section, no stress-relieving effect can be expected for loads applied perpendicular to the thickness direction.

[0005] In contrast, Patent Document 2 discloses a busbar for a battery pack that serves as a stress-relieving busbar. The first mounting surface 11 and the second mounting surface 12 are arranged parallel to the XY plane; the first upright surface 13 and the second upright surface 14 are arranged parallel to or inclined relative to the YZ plane; the connecting surface 15 is arranged parallel to or inclined relative to the XZ plane; the second upright surface is arranged parallel to or inclined relative to the YZ plane from a side portion of the second mounting surface on the same side as the first mounting surface in the X direction; the connecting surface has a U-shaped concave portion that bends in a direction intersecting the Y direction; a first curved portion or inclined portion is formed between the first mounting surface and the first upright surface; and a second curved portion or inclined portion is formed between the second mounting surface and the second upright surface.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2007-73266

[0009] Patent Document 2: Japanese Patent Application Publication No. 2017-73398 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] This invention relates to a busbar manufactured using USW (Ultrasonic Welding) in a joining method that involves stacking and joining multiple metal plates in the thickness direction, and to a battery pack using the busbar. USW joining allows for the production of USW-jointed busbars at a lower cost compared to press-fitting or FSW (Friction Stir Welding), as it does not require large-scale equipment. However, as mentioned above, these joining methods require a joint in the overlapping area of ​​the multiple plates, thus limiting the upper limit of the joint strength due to the influence of the overlapping area in the planar direction of the plates.

[0012] Busbars are configured to be installed between the positive and negative electrode terminals of adjacent batteries. Typically, the shape of a busbar is a roughly flat plate that connects the positive and negative electrode terminals. However, when USW busbars are made into a roughly flat plate shape, especially when the straight-line distance between the terminals is short, the overlapping area in the planar direction between the plates becomes narrow, which can easily lead to problems with the bonding strength.

[0013] Methods for solving problems

[0014] To address the aforementioned problems, this invention utilizes a busbar with a shape that increases the overlap area of ​​the metal plates to be joined in one direction. According to a first aspect of the invention, as a method to provide the busbar with a stress-mitigating three-dimensional structure while ensuring the joint strength of the joint surfaces, a first component and a second component are overlapped, and the overlap is joined by ultrasonic bonding to obtain a joint area, thereby increasing the reliability of the joint strength. This reduces the risk of fatigue failure of the busbar disposed within the battery pack.

[0015] Specifically, the present invention uses a battery pack comprising: a plurality of stacked individual cells, each individual cell having a positive terminal and a negative terminal; and a busbar connecting the positive terminal of a first individual cell to the negative terminal of a second individual cell. The busbar includes: a positive-side conductive member engaging with the positive terminal of the first individual cell; and a negative-side conductive member engaging with the negative terminal of the second individual cell located adjacent to the first individual cell. The positive terminal and the positive-side conductive member are made of a different material than the negative terminal and the negative-side conductive member. The positive-side conductive member has a first engagement portion engaging with the positive terminal and a first extension portion extending from the first engagement portion. The negative-side conductive member has a connection with the negative terminal. The second joint of the terminal engagement and the second extension extending from the second joint and extending to the same side as the first extension relative to the virtual line passing through the first joint and the second joint, have a third joint formed by the engagement of the first extension and the second extension. Viewed from the direction in which the busbar overlaps with the single cell, the end of the positive electrode conducting member is configured to be far from the end of the negative electrode conducting member opposite to the positive electrode conducting member relative to the virtual line connecting the first joint and the second joint. The third joint is formed in the overlapping portion obtained by the overlap of the first extension and the second extension, and the area in which the third joint is located satisfies the condition that the distance of the third joint from one of the first joint and the second joint is closer than the other.

[0016] Invention Effects

[0017] By using the busbar of the present invention, it can deform three-dimensionally in different directions, thus providing stress relief for loads from any direction. Furthermore, it features a large joint area in the planar direction of the overlapping plates, thereby significantly improving the stress resistance of the joint surface. Therefore, it is possible to manufacture a battery pack with a low risk of fatigue failure of the busbar. Attached Figure Description

[0018] Figure 1 This is an exploded perspective view of the battery pack of the present invention.

[0019] Figure 2This is a perspective view of the busbar in Example 1.

[0020] Figure 3 This is an exploded perspective view of the busbar in Example 1.

[0021] Figure 4 This is a three-dimensional view of the busbar for the comparative example.

[0022] Figure 5 This is a perspective view of the busbar in Example 2.

[0023] Figure 6 This is an exploded perspective view of the busbar in Example 2.

[0024] Figure 7 This is a perspective view of the busbar in Example 3.

[0025] Figure 8 This is an exploded perspective view of the busbar in Example 3.

[0026] Figure 9 This is a perspective view of the busbar in Example 4.

[0027] Figure 10 This is a perspective view of the busbar in Example 5.

[0028] Figure 11 This is a perspective view of the busbar in Example 6.

[0029] Figure 12 This is a perspective view of the busbar in Example 7.

[0030] Figure 13 This is a perspective view of the busbar in Example 8.

[0031] Figure 14 This is a perspective view of the busbar in Example 9.

[0032] Figure 15 This is a perspective view of the busbar in Example 10. Detailed Implementation

[0033] The following is related to the appendix. Figure 1 Examples illustrating the battery pack busbar and battery pack of the present invention are provided. Figure 1 This is an exploded perspective view showing an example of a battery pack in which the present invention is applied. For example... Figure 1 As shown, the battery pack 1 has a structure in which a large number of individual cells 2 are fixed by a pair of end plates 4 and a pair of side plates 5. The individual cells 2 are, for example, square secondary cells such as lithium-ion secondary batteries.

[0034] The square single battery 2 is a cuboid shape with a top surface, a bottom surface, a pair of large-area flat surfaces, and a pair of small-area side surfaces. The size of the single battery 2 is, for example, 12cm on the long side, 1.2cm on the short side, and 6.5cm in height; this is just an example, and the single battery can take various sizes. The single batteries 2 are arranged in a row with their large-area flat surfaces facing each other. A retainer 3 is provided between each single battery 2, in front of the first single battery 2 in the row, and behind the last single battery 2 in the row.

[0035] Each single cell 2 has a positive electrode 2a and a negative electrode 2b on its upper side, both having the same size, shape, and structure. Adjacent single cells 2 have their positive electrodes 2a and negative electrodes 2b facing each other; in other words, the positive and negative planes are arranged alternately. The positive electrode 2a is formed, for example, of an aluminum-based metal such as aluminum or an aluminum alloy, and the negative electrode 2b is formed, for example, of a copper-based metal such as copper or a copper alloy.

[0036] End plates 4 are arranged in front of the retainer 3 at the beginning of the column and behind the retainer 3 at the end of the column. Each pair of end plates 4 is made of metal, is approximately rectangular in shape, and has openings 4a at each of the four corners for bolts 6 to pass through. A pair of side plates 5 are arranged on the sides of the single cells 2 arranged in a row. Each side plate 5 is a rectangular frame including a horizontal beam portion spaced apart vertically and a connecting portion connecting the horizontal beam portion. Openings 5a are formed at each corner of the frame corresponding to the openings 4a of the end plates 4.

[0037] The battery pack 1 is formed by placing the end plates 4 at the beginning and rear of the column inside the front and rear connecting parts of each side plate 5, and fixing them by inserting bolts 6 into the openings 5a of the side plates 5 and the openings 4a of the end plates 4. The bolts 6 are screwed into threaded holes (not shown) formed in the retainer 3, or are fastened by placing nuts (not shown) on the back side of the end plates 4. Rivets can also be used instead of bolts 6 for fastening.

[0038] An insulating cover 7 is provided on the upper side of each individual cell 2, surrounding the positive / negative electrodes 2a and 2b of the cells 2 arranged in a row. The positive electrodes 2a and negative electrodes 2b of adjacent cells 2 are connected by busbars 10. All cells 2 are connected in series by busbars 10. End busbars 8 are connected to the positive electrode 2a1 of the cell 2 at the beginning of the row and the negative electrode 2b1 of the cell 2 at the end of the row. The busbars 10 or the end busbars 8 are joined to the positive / negative electrodes 2a and 2b by welding such as laser welding or ultrasonic welding. Alternatively, a structure in which the connection is made by threaded fastening without welding can also be used.

[0039] The busbars 10 disposed at one of the series of insulating covers 7 have substantially the same shape and structure. The busbars 10 disposed at the other of the series of insulating covers are substantially mirror-symmetrical in shape to the busbars 10 disposed at one of the insulating covers 7. The end busbars 8 have a mounting surface that connects to one of the positive / negative electrodes 2a, 2b of the single cell 2, and a through hole for screw fastening is provided at the end opposite to the mounting surface. The invention is characterized by the structure of the busbars 10, and one embodiment of the busbars 10 will be described below.

[0040] (Example 1)

[0041] Figure 2 yes Figure 1 The diagram shows a perspective view of the external appearance of the busbar 10 for the battery pack in Embodiment 1. Figure 3 This is an exploded perspective view. The busbar 10 includes a first plate 11 and a second plate 12. The first plate 11 is formed by stamping a metal sheet composed of aluminum or aluminum alloys, copper or copper alloys, iron, or other metals. The second plate 12 is made of a different material than the first plate 11 and is formed by stamping a metal sheet composed of aluminum or aluminum alloys, copper or copper alloys, iron, or other metals. In the following description, the X direction, the Y direction perpendicular to the X direction, and the Z direction perpendicular to both the X and Y directions are as follows: Figure 3 As shown.

[0042] The busbar 10 includes a first plate 11 and a second plate 12. The first plate 11 is a positive-side conductive member that engages with the positive terminal 2a of the first single cell, and the second plate 12 is a negative-side conductive member that engages with the negative terminal 2b of the second single cell located adjacent to the first single cell. The first plate 11, as a positive-side conductive member, has a first engagement portion 111 that engages with the positive terminal 2a, and a first extension portion 112 that extends from the first engagement portion 111.

[0043] On the other hand, the second plate 12, which is a negative electrode side conduction component, has a second joint portion 121 that engages with the negative electrode 2b, and a second extension portion 122 that extends from the second joint portion 121 and extends to the same side as the first extension portion 112 relative to the virtual line passing through the first joint portion 111 and the second joint portion 121.

[0044] In addition, the busbar 10 also has a third extension 13, which extends from the end face of the extension 112 or 122 from at least one of the first extension 111 and the second extension 121. The third extension 13 extends substantially parallel to the overlapping direction of the single battery 2 and has a third joint 131, which is formed by ultrasonically joining the third extension 13 to at least a portion of the surface of the other extension 112 or 122. The third joint 13 is located at a position perpendicular to the virtual line connecting the first joint 111 and the second joint 121. Furthermore, the ends of the first plate 11, which serves as the positive electrode conducting member, and the ends of the second plate 12, which serves as the negative electrode conducting member, are located at a spaced-apart position. That is, the ends are not joined together. Furthermore, the third joint 131 is configured such that the distance between it and one of the first joint 111 and the second joint 121 is shorter than the distance between it and the other.

[0045] Reasons for using this shape of busbar 10 include the need for the portion of the busbar 10 disposed above the terminal to be flat. That is, if the portion of the busbar disposed above the terminal is not flat, there is a possibility of poor pressing during subsequent processes when joining the terminal to the busbar, leading to poor bonding. On the other hand, in the case of USW (Ultrasonic welding) bonding, the characteristic weld marks of USW bonding are produced. As a result, the upper and lower surfaces of the busbar become uneven. In this regard, the use of the busbar 10 of the present invention has the advantage of maintaining the flatness of the upper part of the terminal and increasing the area for joining the first plate 11 and the second plate 12. Therefore, the bonding strength between the first plate 11 and the second plate 12 can be improved.

[0046] That is, in a simple overlapping structure, when a third joint is used on the upper and lower surfaces connecting the positive and negative terminals, the required flatness necessitates a reduction in the joint area. This problem is solved by using the busbar 10 of the present invention. Using the busbar 10 of the present invention, joint marks do not extend into the upper surface of the terminals of the busbar 10, thus increasing the joint area.

[0047] The specific possible bonding area is calculated as follows. The area described here refers to the area in the planar direction of the plates. That is, let the width of the first plate 11 be A, the width of the second plate 12 be B, the distance between the first plate 11 and the second plate 12 be C, and the width of the third extension be D. In this case, the maximum area S1 capable of ultrasonic bonding in the busbar of the present invention can be expressed as S1 = (A + B + C) × D. Furthermore, as examples of A, B, C, and D, A = 1 cm, B = 1 cm, C = 5 mm, and D = 2 mm to 10 mm. Furthermore, as examples of the plate thickness of the first plate 11 and the second plate 12, it is, for example, 0.5 mm to 1.5 mm, more preferably about 0.6 mm to 0.8 mm.

[0048] However, the dimensions described above are merely examples. The widths of A, B, C, and D are not particularly limited; they can be any size as long as they can be installed in a battery module or battery pack. Furthermore, the mating surface only needs to be the area where the extension overlaps with the other plate; the effects of this invention can be achieved regardless of the area or position of the arrangement.

[0049] At this time, it is also possible to have a third extension 13 or a fourth extension extending from the end face of both the first extension 112 and the second extension 122. In this case, the maximum area S1 is also as follows. Figure 2 As shown. In addition, voltage detection lines can be installed in the portions of the first extension 112, the third extension 131, and the second extension 122 of the busbar 10 where the USW joint is not provided.

[0050] Nickel plating can also be applied to at least one of the first plate 11 and the second plate 12 in the busbar 10, on the surface where the first plate 11 and the second plate 12 are physically connected to each other. Nickel plating can also be applied to both the first plate 11 and the second plate 12. The surface to be nickel plated can be a part of the surface where the first plate 11 and the second plate 12 are physically connected to each other, or it can be the entire surface. Alternatively, nickel plating can be applied to only the surface where the first plate 11 and the second plate 12 are physically connected to each other, or it can be applied to other surfaces in the plate.

[0051] By applying nickel plating to the surfaces where the first plate 11 and the second plate 12 are physically connected, the process margin for bonding aluminum-based metals and copper-based metals can be increased, resulting in improved bonding strength. Furthermore, it is expected to inhibit corrosion of the aluminum-based metals. The thickness of the nickel plating is preferably 1 μm to 100 μm, more preferably 3 μm to 50 μm, and most preferably 4 μm to 10 μm. Increasing the thickness of the nickel plating also increases the process margin for USW bonding. The gloss level of the nickel plating includes matte, semi-gloss, and glossy plating; any gloss level can be selected depending on the bonding conditions.

[0052] Glossiness can be measured using a gloss meter. Specifically, in a measurement using a gloss meter, the intensity I of incident light from directly above the surface of the plate is measured. in The intensity I of the reflected light reflected at a 45-degree angle relative to the incident light. out log(I) of the reciprocal of the ratio in / I out When the gloss level is specified, it is preferably 0.2 to 2.5, more preferably 0.3 to 2.5, and most preferably 0.6 to 2.5. By setting the gloss level within this range, the process margin for USW bonding can also be increased.

[0053] A specific example of the combination in Embodiment 1 is given. The first plate 11 can be made of pure aluminum, the second plate 12 can be made of oxygen-free copper, and the surface of the second plate 12 is coated with a nickel-plated material. The nickel plating thickness can be 5 μm, and the gloss level can be 2.0. Electroplating and electroless electroplating are methods for nickel plating. Any method can be used as long as USW bonding is possible, but electroplating is preferred.

[0054] Figure 4 This is a perspective view showing a comparative example of busbar 10. Figure 4 In this structure, the first plate 11 and the second plate 12, both flat, are joined at their end faces. This structure will be referred to below as a flat composite material. Figure 4 In this configuration, the first plate 11 and the second plate are joined at the joint surface 30. Centered on the joint surface 30, a width w in the planar direction of the plates forms a mixed region 31 of the materials constituting the first plate 11 and the second plate. The width w is, for example, 1 mm. Figure 4 The structure shown does not exhibit indentations caused by USW, thus ensuring reliable connection of the positive or negative electrode. However, Figure 4 Flat composite materials have the problem of high cost.

[0055] (Example 2)

[0056] Figure 5 This is a perspective view of Embodiment 2. Compared with Embodiment 1, Embodiment 2 is configured such that, in addition to the third extension 13, a protrusion 113 for mounting a voltage detection line is provided on the end face of the extension 112 extending from the first plate 11. Figure 6 yes Figure 5An exploded perspective view. The structure is otherwise identical to that of Embodiment 1. Furthermore, although not shown here, a protrusion 113 for mounting a voltage detection line may be provided in the extension 122 extending from the second plate 12. Similarly, in this case, the maximum area S2 in the planar direction of the plate in the busbar of the present invention capable of ultrasonic bonding is S2 = (A + B + C) × D, thus increasing the bonding area.

[0057] (Example 3)

[0058] Figure 7 This is a perspective view of Example 3. Figure 7 Compared to the structure of Embodiment 1, the first extension 112 and the second extension 122 located on the first plate 11 and the second plate 12 are bent to have a third extension 13 extending from both the extensions 112 and 122. Figure 8 yes Figure 7 An exploded perspective view is provided. The structure is otherwise identical to that of Embodiment 1. Similarly, in the busbar 10 of Embodiment 3, the maximum area S3 in the planar direction of the plate capable of ultrasonic bonding is S3 = (A + B + C) × D, resulting in a large area. In this case, the bending angle can be arbitrary, as long as it can be installed in a battery module or battery pack. This embodiment shows a 45-degree angle, but even with a 90-degree angle, the maximum area capable of ultrasonic bonding will not change. Furthermore, in the first extension 112 and the second extension 122 of the busbar 10, voltage detection lines can be installed at locations where USW bonding portions are not provided.

[0059] (Example 4)

[0060] Figure 9 This is a perspective view of Example 4. Figure 9 In Embodiment 3, a protrusion 114 for mounting a voltage detection line is added to the first plate 11 in the direction opposite to the first extension. The structure is otherwise the same as in Embodiment 3. Similarly, in Embodiment 4, the maximum area S4 in the planar direction of the busbar capable of ultrasonic bonding according to the present invention can be expressed as S4 = (A + B + C) × D, thus increasing the bonding area.

[0061] (Example 5)

[0062] Figure 10 This is a perspective view of Example 5. Figure 10In Embodiment 3, the first extension 112 and the second extension 122 located on the first plate 11 and the second plate 12 are bent to form a third extension 13 extending from one of the extensions 112 or 122. The third extension 13 is provided with an arched structure (arch bridge structure) 14 for stress mitigation. In Embodiment 5, the bending angle of the third extension relative to the first and second extensions is set to 90 degrees, but other angles can also achieve the same effect. The structure is otherwise the same as in Embodiment 3. In this case, if the length of the arched structure 14 is E, the maximum area S5 in the plane direction of the busbar 10 capable of ultrasonic bonding can be expressed as S5 = (A + CE) × D or S5 = (B + CE) × D, thus increasing the bonding area.

[0063] (Example 6)

[0064] Figure 11 This is a perspective view of Example 6. Figure 11 In Embodiment 1, the structure includes a third extension 13 extending in a second direction from one of the first extension 112 and the second extension 122 located on the first plate 11 and the second plate 12, when viewed from above. The structure is otherwise identical to Embodiment 1. Similarly, in Embodiment 6, the maximum area S6 in the planar direction of the busbar 10 capable of ultrasonic bonding can be expressed as S6 = A × D or S6 = B × D, thus increasing the bonding area.

[0065] (Example 7)

[0066] Figure 12 This is a perspective view of Example 7. Figure 12 In the structure of Embodiment 1, the first extension 112 and the second extension 122 located on the first plate 11 and the second plate 12 are bent to form a third extension 13 extending from one of the extensions, and an arched structure 14 is provided in a portion of the third extension 13. The structure is otherwise the same as in Embodiment 1. In this case, the maximum area S7 in the planar direction of the plate in the busbar of the present invention, which is capable of ultrasonic bonding, can be expressed as S7 = (A + CE) × D or S7 = (B + CE) × D, thereby increasing the bonding area.

[0067] (Example 8)

[0068] Figure 13 This is a perspective view of Example 8. Figure 13In Embodiment 3, the structure is formed by bending the first extension 112 and the second extension 122 located on the first plate 11 and the second plate 12, resulting in a third extension 13 extending from one of these extensions. In Embodiment 8, the bending angle is set to 90 degrees, but the same effect can be obtained by using other angles. The structure is otherwise the same as in Embodiment 3. Similarly, in Embodiment 8, the maximum area S8 in the plane direction of the busbar 10 capable of ultrasonic bonding can be expressed as S8 = A × D or S8 = B × D, thereby increasing the bonding area.

[0069] (Example 9)

[0070] Figure 14 This is a perspective view of Example 9. Figure 14 A protrusion 114 for mounting voltage detection is provided on one of the first plate 11 and the second plate 12; otherwise, the structure is the same as in Embodiment 5. In Embodiment 9, the bending angle of the third extension 13 relative to the first extension 112 or the second extension 122 is set to 90 degrees, but the same effect can be obtained by using other angles. In this case, if the length of the arched structure 14 is E, the maximum area S9 in the plane direction of the busbar in the present invention that can be ultrasonically bonded can be expressed as S9 = (A + CE) × D or S9 = (B + CE) × D, which can increase the bonding area.

[0071] (Example 10)

[0072] Figure 15 This is a perspective view of Example 10. Figure 15 The structure involves bending the first extension 112 and the second extension 122 located on the first plate 11 and the second plate 12, respectively, to form a third extension 13 extending from one of the extensions 112 or 122. The extension 13 is the opposite of the structure in Embodiment 8. Furthermore, the orientation of the USW welding head and the anvil can be such that the welding head is on the side of the first plate 11 and the anvil is on the side of the second plate 12, or the welding head is on the side of the second plate 12 and the anvil is on the side of the first plate 11. Either way, the effects of the present invention can be achieved. In Embodiment 10, the bending angle is set to 90 degrees, but the same effect can be obtained by using other angles. The structure is otherwise the same as in Embodiment 3. Similarly, in Embodiment 10, the busbar 10, which allows for ultrasonic bonding, has a maximum area S3 in the planar direction of the plate that can be represented as S3 = (A + B + C) × D, thus increasing the bonding area.

[0073] Furthermore, the above embodiments are merely examples. For instance, the effects of the present invention can be obtained even when the thicknesses of the first plate 11 and the second plate 12 are changed. The position and area of ​​the connecting surfaces in the busbar 10 can be varied according to the length of each extension 3. In addition, curved portions, bends, inclined portions, or stepped portions can be appropriately added to the flat portions of each extension. Furthermore, the structures shown in the above embodiments can be combined.

[0074] The installation method for the busbar and voltage detection line in this invention is not particularly limited; for example, ultrasonic bonding, laser welding, thread fastening, riveting, etc., can be used. Furthermore, regarding the structure provided on the busbar for leading out the voltage detection line, it can be placed at the required location on the busbar as long as it does not interfere with other components of the battery pack. And its shape can also be varied.

[0075] For example, as shown in the embodiment, it can be provided as an extension in a direction parallel to the surface of the busbar, or as a protrusion in a direction perpendicular to the surface of the busbar. The protrusion can be not only flat, but also a complex three-dimensional structure. A press-fit connector can also be installed on the protrusion to install a voltage detection line. The protrusion can be freely constructed in a three-dimensional manner according to the size of the press-fit connector and the operability of the connector within the battery pack.

[0076] This invention is not limited to the busbar 10 connecting lithium-ion secondary batteries, but can also be applied to busbars connecting secondary batteries that use water-soluble electrolytes, such as nickel-metal hydride batteries, nickel-cadmium batteries, and lead-acid batteries. Furthermore, this invention can also be applied to busbars connecting energy storage components such as lithium-ion capacitors and electrolytic double-layer capacitors.

[0077] Furthermore, the battery pack busbar 10 of the present invention can be applied after undergoing various modifications.

[0078] Explanation of reference numerals in the attached figures

[0079] 1…Battery pack

[0080] 2…Single battery

[0081] 2a…Positive electrode

[0082] 2b…Negative electrode

[0083] 3…cage

[0084] 4…End plate

[0085] 4a…Opening

[0086] 5…side panels

[0087] 5b…Opening

[0088] 6… Bolts

[0089] 7…Insulating cover

[0090] 8…End busbar

[0091] 10…busbars

[0092] 10… Display Panel

[0093] 11… First plate (positive side conductive component)

[0094] 12…Second plate (negative side conductive component)

[0095] 13… Third Extension

[0096] 14…Arch structure

[0097] 20…End of electrode terminal

[0098] 30…Matching surface

[0099] 31… Mixed Area

[0100] 111…First joint

[0101] 112…First Extension

[0102] 113…First protrusion

[0103] 114…Second protrusion

[0104] 121…Second joint

[0105] 122…Second Extension

[0106] 131… Third joint.

Claims

1. A battery pack, characterized in that: The first battery and the second battery are arranged in a second direction intersecting the first direction. In the first battery, the first positive terminal and the first negative terminal are arranged at a first interval in the first direction, and in the second battery, the second positive terminal and the second negative terminal are arranged at a second interval in the first direction. The first positive terminal and the second negative terminal are arranged adjacent to each other in the second direction, and are connected by a busbar, wherein... The first conductive component of the busbar has a first engagement portion that engages with the first positive terminal, and a first extension portion that extends from the first engagement portion in the first direction. The second conductive component of the busbar has a second engagement portion that engages with the second negative terminal, and a second extension portion extending from the second engagement portion in the first direction. The first conductive component and the second conductive component are made of different materials. The first conductive component and the second conductive component are connected at the third joint by ultrasonic welding. The ends of the first extension and the second extension are spaced apart from the line connecting the first joint and the second joint in the first direction. The third joint is formed at the overlap of the first extension and the second extension, and one of the distances between the third joint and the first joint and between the third joint and the second joint is closer than the other. The first extension also has a third extension extending in the second direction. The third joint is located at the overlap between the second extension and the third extension.

2. The battery pack as described in claim 1, characterized in that: The second extension also has a fourth extension extending in the second direction. The third joint is located at the overlap of the third extension and the fourth extension.

3. The battery pack as described in claim 1, characterized in that: The first conducting component or the second conducting component has a protrusion for voltage detection in the first direction when viewed from above.

4. The battery pack as described in claim 1 or 2, characterized in that: The surface on which the third joint is formed has an angle relative to the surfaces on which the first joint and the second joint are formed.

5. The battery pack as described in claim 1 or 2, characterized in that: The first extension and the second extension are joined by nickel or a nickel alloy.

6. The battery pack as described in claim 1, characterized in that: The third extension has an arched structure outside the area where the third joint is formed.

7. The battery pack as described in claim 2, characterized in that: The third extension or the fourth extension has an arched structure outside the area where the third joint is formed.

8. The battery pack as described in claim 1, characterized in that: The first battery and the second battery are cuboids. The first positive electrode and the first negative electrode of the first battery are formed on the same face of the cuboid, and the second positive electrode and the second negative electrode of the second battery are formed on the same face of the cuboid.

9. The battery pack as described in claim 1, characterized in that: Multiple groups of the first battery and the second battery are arranged in the second direction.

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