Battery cell stack

Abstract

The present disclosure provides a battery cell stack having a rectangular parallelepiped shape in which a plurality of rectangular battery cells are stacked, and each of the plurality of rectangular battery cells includes a terminal provided in an end face thereof in a longitudinal direction. The cell stack includes a plate-shaped bus bar configured to electrically connect terminals of adjacent rectangular cells to each other. The bus bar includes: a first slit extending in a stacking direction of the rectangular battery cells such that at least a portion of the first slit overlaps a region spanning a pair of welded portions welded to respective terminals of adjacent rectangular battery cells; and a second slit extending parallel to the first slit beyond a region across the pair of welded portions. The width of the first slit is larger than that of the second slit.

Description

Technical Field

[0001] The present disclosure relates to a battery cell stack. Background Art

[0002] In a battery cell stack according to the related art, a terminal is provided on the upper surface of each rectangular battery cell in the (hereinafter, stacked) rectangular battery cell stack. In recent years, as disclosed in Patent Document 1, a battery cell stack has been developed in which each rectangular battery cell in the stack is provided with a terminal on its longitudinal end face.

[0003] Patent Document 1: U.S. Patent Application Publication No. 2022 / 0302533. Summary of the Invention

[0004] The inventors have discovered the following problem in a battery cell stack in which each rectangular battery cell is provided with a terminal on its longitudinal end face. In this battery cell stack, a flat busbar is welded to each of the terminals of adjacent rectangular battery cells, thereby electrically connecting the terminals of the adjacent rectangular battery cells. In a battery cell stack mounted on a vehicle, for example, stress is repeatedly applied to the welded portions of the busbar due to vertical movement of the vehicle.

[0005] The present disclosure has been made in view of the above circumstances, and provides a battery cell stack capable of relieving stress acting on a weld portion of a bus bar and improving fatigue life of the weld portion.

[0006] A battery cell stack according to one aspect of the present disclosure has a rectangular parallelepiped shape, a plurality of rectangular battery cells are stacked in the battery cell stack, and each of the plurality of rectangular battery cells includes a terminal provided in an end face in a longitudinal direction thereof, The battery cell stack includes a plate-shaped bus bar configured to electrically connect terminals of adjacent rectangular battery cells to each other. The busbar includes: a first slit extending in the stacking direction of the rectangular battery cells so that at least a portion of the first slit overlaps an area spanning a pair of welds welded to respective terminals of adjacent rectangular battery cells; and a second slit extending parallel to the first slit outside a region spanning the pair of welds, The width of the first slit is greater than the width of the second slit.

[0007] In the battery cell stack according to the present disclosure, the plate-shaped busbar electrically connecting the terminals of adjacent rectangular battery cells includes: a first slit extending in the stacking direction of the rectangular battery cells, such that at least a portion of the first slit overlaps an area spanning a pair of welds welded to the terminals of the adjacent rectangular battery cells; and a second slit extending parallel to the first slit outside the area spanning the pair of welds. Furthermore, the width of the first slit is greater than the width of the second slit. With the above structure, the stress acting on the welded portion of the busbar can be relieved, and the fatigue life of the welded portion can be improved.

[0008] The second slit may be longer than the first slit. Through the above structure, the stress acting on the welding portion of the busbar can be further relieved, and the fatigue life of the welding portion can be further improved.

[0009] The battery cell stack may further include a third slit, disposed opposite the second slit across the first slit and extending parallel to the first slit. The width of the third slit may be smaller than the width of the first slit. This structure reduces heat generated by the busbar when energized, further reduces stress on the busbar welds, and further improves fatigue strength of the welds.

[0010] The third slit may be longer than the first slit. Through the above structure, the stress acting on the welding portion of the busbar can be further relieved, and the fatigue strength of the welding portion can be further improved.

[0011] The width of the third slit may be the same as the width of the second slit. The above structure can easily form a slit in the busbar.

[0012] The busbar has a hat-shaped cross section and can protrude outward from between the pair of welded portions. Through the above structure, the stress acting on the welded portions of the busbar can be further relieved, and the fatigue life of the welded portions can be further improved.

[0013] According to the present disclosure, a battery cell stack capable of relieving stress acting on a weld portion of a bus bar and improving fatigue life of the weld portion can be provided. The above and other objects, features and advantages of the present disclosure will be more fully understood from the detailed description and accompanying drawings given below. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a perspective view showing a battery cell stack according to a first embodiment; Figure 2 is a perspective view showing a battery cell stack according to a first embodiment; Figure 3 is the plan view of busbar B1; Figure 4 It is along Figure 3 A cross-sectional view taken along the cutting line IV-IV; Figure 5 is a plan view of a busbar B101 according to a comparative example; Figure 6 is a plan view of a busbar B1 according to a first modified example; Figure 7 is a plan view of a busbar B1 according to a second modified example; and Figure 8 is a plan view of a busbar B1 according to a third modified example. DETAILED DESCRIPTION

[0015] The following will describe in detail specific embodiments of the present disclosure with reference to the accompanying drawings. However, the present disclosure is not limited to the following embodiments. Further, for the sake of clarity, the following description and drawings will be appropriately simplified.

[0016] (First embodiment) <Battery Cell Stack Structure> First, refer to Figure 1 and Figure 2 The structure of the battery cell stack according to the first embodiment will be described. Figure 1 and Figure 2 Each of them is a perspective view showing a battery cell stack according to the first embodiment. It is worth noting that, undoubtedly, Figure 1 and Figure 2 The right-handed XYZ rectangular coordinate system shown in the other figures is only for the convenience of explaining the positional relationship between the components. Figure 1 、 Figure 2 In the figure, the positive direction of the Z axis is the vertical upward direction, and the XY plane is the horizontal plane, and the direction and plane are the same throughout the entire figure.

[0017] like Figure 1 and Figure 2 As shown, the battery cell stack CS according to the present embodiment includes rectangular battery cells C1 to C6 and bus bars B1 to B5 . The battery cell stack CS according to this embodiment is used, for example, in a vehicle battery. The vehicle in which the battery cell stack CS according to this embodiment is mounted is not limited to a specific type of vehicle; for example, the vehicle is a vehicle capable of being driven by the power supplied by the battery cell stack CS, such as a pure electric vehicle, a hybrid electric vehicle, and a fuel cell electric vehicle.

[0018] like Figure 1 and Figure 2As shown, rectangular battery cells C1 to C6 are cuboid-shaped battery cells extending in the Y-axis direction. Rectangular battery cells C1 to C6 are stacked in the thickness direction (X-axis direction) to form a battery cell stack CS. Rectangular battery cells C1 to C6 are, for example, secondary batteries such as lithium-ion batteries and nickel-metal hydride batteries.

[0019] It is worth noting that in Figure 1 and Figure 2 In FIG, the battery cell stack CS is shown in a simplified manner. Figure 1 and Figure 2 The illustrated battery cell stack CS is formed of six rectangular battery cells C1 to C6, but is typically formed of a larger number of rectangular battery cells. In practice, the number of rectangular battery cells forming the battery cell stack CS is not limited to any specific number and can be any number greater than two. Furthermore, thermal insulation plates, spacers for adjusting spacing, and the like (not shown) may be inserted between adjacent rectangular battery cells.

[0020] like Figure 1 As shown, the rectangular battery cell C1 is provided with a positive terminal PT1 on one end face in the longitudinal direction thereof (the end face on the negative side of the Y axis). Figure 1 The positive terminal PT1 shown in FIG has a rectangular shape in the XZ plane view and is provided to protrude outward from the end surface of the rectangular battery cell C1. However, the present disclosure is not particularly limited thereto. Further, a positive terminal PT1 is provided on the upper side (positive side of the Z axis) of the end surface of the rectangular battery cell C1. Figure 1 The positive terminal PT1 is shown. The positive terminal PT1 is made of, for example, a metal material having excellent electrical conductivity such as copper.

[0021] Similarly, if Figure 1 As shown, the rectangular battery cell C2 adjacent to the rectangular battery cell C1 is provided with a negative terminal NT2 on one end face in the longitudinal direction (the end face on the negative side of the Y axis). The rectangular battery cell C3 adjacent to the rectangular battery cell C2 is provided with a positive terminal PT3 on one end face in the longitudinal direction (the end face on the negative side of the Y axis). The rectangular battery cell C4 adjacent to the rectangular battery cell C3 is provided with a negative terminal NT4 on one end face in the longitudinal direction (the end face on the negative side of the Y axis). The rectangular battery cell C5 adjacent to the rectangular battery cell C4 is provided with a positive terminal PT5 on one end face in the longitudinal direction (the end face on the negative side of the Y axis). The rectangular battery cell C6 adjacent to the rectangular battery cell C5 is provided with a negative terminal NT6 on one end face in the longitudinal direction (the end face on the negative side of the Y axis).

[0022] like Figure 1As shown, each of the negative terminal NT2 of the rectangular battery cell C2, the positive terminal PT3 of the rectangular battery cell C3, the negative terminal NT4 of the rectangular battery cell C4, the positive terminal PT5 of the rectangular battery cell C5, and the negative terminal NT6 of the rectangular battery cell C6 has a shape similar to the positive terminal PT1 of the rectangular battery cell C1 and is arranged in a manner similar to the manner in which the positive terminal PT1 of the rectangular battery cell C1 is arranged.

[0023] Furthermore, if Figure 1 As shown, the positive terminal PT1 of the rectangular battery cell C1 and the negative terminal NT2 of the rectangular battery cell C2, which are arranged adjacent to each other, are electrically connected to each other via a plate bus bar B1. Similarly, the positive terminal PT3 of the rectangular battery cell C3 and the negative terminal NT4 of the rectangular battery cell C4, which are arranged adjacent to each other, are electrically connected to each other via a plate bus bar B3. Similarly, the positive terminal PT5 of the rectangular battery cell C5 and the negative terminal NT6 of the rectangular battery cell C6, which are arranged adjacent to each other, are electrically connected to each other via a plate bus bar B5.

[0024] At the same time, if Figure 2 As shown, the rectangular battery cell C1 is provided with a negative terminal NT1 on the other end face in the longitudinal direction thereof (the end face on the positive side of the Y axis). Figure 1 As shown in the positive terminal PT1, Figure 2 The negative terminal NT1 shown has a rectangular shape in the XZ plane view and is provided to protrude outward from the end surface of the rectangular battery cell C1. However, the present disclosure is not particularly limited thereto. Further, as Figure 1 As shown in the figure, the positive terminal PT1 is provided on the upper side (Z-axis positive side) of the end face of the rectangular battery cell C1. Figure 2 The negative terminal NT1 is shown. Like the positive terminal PT1, the negative terminal NT1 is made of a metal material having excellent electrical conductivity such as copper.

[0025] Similarly, if Figure 2 As shown, the rectangular battery cell C2 adjacent to the rectangular battery cell C1 is provided with a positive terminal PT2 on its other end face in the longitudinal direction (the end face on the positive side of the Y axis). The rectangular battery cell C3 adjacent to the rectangular battery cell C2 is provided with a negative terminal NT3 on its other end face in the longitudinal direction (the end face on the positive side of the Y axis). The rectangular battery cell C4 adjacent to the rectangular battery cell C3 is provided with a positive terminal PT4 on its other end face in the longitudinal direction (the end face on the positive side of the Y axis). The rectangular battery cell C5 adjacent to the rectangular battery cell C4 is provided with a negative terminal NT5 on its other end face in the longitudinal direction (the end face on the positive side of the Y axis). The rectangular battery cell C6 adjacent to the rectangular battery cell C5 is provided with a positive terminal PT6 on its other end face in the longitudinal direction (the end face on the positive side of the Y axis).

[0026] like Figure 2 As shown, each of the positive terminal PT2 of the rectangular battery cell C2, the negative terminal NT3 of the rectangular battery cell C3, the positive terminal PT4 of the rectangular battery cell C4, the negative terminal NT5 of the rectangular battery cell C5, and the positive terminal PT6 of the rectangular battery cell C6 has a shape similar to the negative terminal NT1 of the rectangular battery cell C1 and is arranged in a manner similar to the manner in which the negative terminal NT1 of the rectangular battery cell C1 is arranged.

[0027] Furthermore, if Figure 2 As shown, the positive terminal PT2 of the rectangular battery cell C2 and the negative terminal NT3 of the rectangular battery cell C3, which are arranged adjacent to each other, are electrically connected to each other through the plate bus bar B2. Similarly, the positive terminal PT4 of the rectangular battery cell C4 and the negative terminal NT5 of the rectangular battery cell C5, which are arranged adjacent to each other, are electrically connected to each other through the plate bus bar B4. As described above, Figure 1 and Figure 2 In the illustrated battery cell stack CS, rectangular battery cells C1 to C6 are connected in series with one another via bus bars B1 to B5 .

[0028] It is worth noting that Figure 2 The negative terminal NT1 of the rectangular battery cell C1 shown is connected to the positive terminal of another battery cell stack through, for example, a bus bar (not shown). However, the present disclosure is not particularly limited thereto. Further, Figure 2 The positive terminal PT6 of the rectangular battery cell C6 is connected to the negative terminal of another battery cell stack via a bus bar (not shown). However, the present disclosure is not particularly limited thereto. With the above structure, for example, multiple battery cell stacks can be connected in series.

[0029] because Figure 1 and Figure 2 The illustrated bus bars B1 to B5 have similar structures to one another, and thus the bus bar B1 will be described. like Figure 1 As shown, bus bar B1 is a plate-shaped member that electrically connects the positive terminal PT1 of rectangular battery cell C1 and the negative terminal NT2 of rectangular battery cell C2 disposed adjacent to each other. Bus bar B1 is made of, for example, a metal material having excellent conductivity such as copper.

[0030] like Figure 1As shown, busbar B1 includes a pair of welds WP1 and WP2, which are welded to the positive terminal PT1 of the adjacent rectangular battery cell C1 and the negative terminal NT2 of the rectangular battery cell C2, respectively. Busbar B1 includes a first slit S1 and a second slit S2. The first slit S1 extends in the stacking direction (X-axis direction) so that it overlaps the region spanning the pair of welds WP1 and WP2. The second slit S2 extends parallel to the first slit S1 outside the region spanning the pair of welds WP1 and WP2. Notably, the width of the first slit S1 is greater than the width of the second slit S2.

[0031] As described above, in the battery cell stack CS according to this embodiment, the width of the first slit S1 formed to overlap the region spanning the pair of welds WP1 and WP2 is greater than the width of the second slit S2 formed outside the region spanning the pair of welds WP1 and WP2. Therefore, the stress acting on the welds WP1 and WP2 of the busbar B1 is relieved, and the fatigue life of the welds WP1 and WP2 is improved.

[0032] <Detailed structure of busbar> The following will refer to Figure 3 and Figure 4 The detailed structure of busbar B1 is described. Figure 3 is the plan view of busbar B1. Figure 4 It is along Figure 3 A cross-sectional view taken along cutting line IV-IV. It is worth noting that Figure 3 and Figure 4 Also shown are the positive terminal PT1 of the rectangular battery cell C1 and the negative terminal NT2 of the rectangular battery cell C2. Figure 3 Although it is a plan view, the busbar B1 is represented by a dot pattern for easier understanding.

[0033] like Figure 3 As shown, busbar B1 is a plate-like member having a rectangular shape in an XZ plane view. Busbar B1 is provided to substantially cover the entire positive terminal PT1 of the rectangular battery cell C1 and the entire negative terminal NT2 of the rectangular battery cell C2. As described above, busbar B1 includes a pair of welded portions WP1 and WP2, which are respectively welded to the positive terminal PT1 of the rectangular battery cell C1 and the negative terminal NT2 of the rectangular battery cell C2, which are arranged adjacent to each other.

[0034] It is worth noting that Figure 3 and Figure 4Welding portions WP1 and WP2 before welding are shown. For example, by irradiating welding portion WP1 with a laser beam from the negative side of the Y axis, busbar B1 is welded to the positive terminal PT1 of rectangular battery cell C1 in welding portion WP1. However, the present disclosure is not particularly limited to this. Similarly, by irradiating welding portion WP2 with a laser beam from the negative side of the Y axis, busbar B1 is welded to the negative terminal NT2 of rectangular battery cell C2 in welding portion WP2.

[0035] Figure 3 The illustrated welded portions WP1 and WP2 are provided at respective ends of the busbar B1 on the lower side in the X-axis direction (the negative side in the Z-axis direction). However, the present disclosure is not particularly limited thereto. Figure 3 and Figure 4 Each of the illustrated welding portions WP1 and WP2 has a circular shape in an XZ plane view and includes a through hole at the center thereof. However, the present disclosure is not particularly limited thereto. Further, as Figure 4 As shown, each of the welded portions WP1 and WP2 is counterbored, and its plate thickness is smaller than that of other regions of the busbar B1.

[0036] It is worth noting that Figure 3 As shown, the first slit S1 extends in the stacking direction (X-axis direction) within the region spanning the pair of welded portions WP1 and WP2. Furthermore, the second slit S2 extends parallel to the first slit S1 outside the region spanning the pair of welded portions WP1 and WP2. It is noteworthy that the width of the first slit S1 is greater than that of the second slit S2.

[0037] It is worth noting that in Figure 3 In the figure, the region spanning the pair of welds WP1 and WP2 is the region enclosed by a circle defining the outer edges of the pair of welds WP1 and WP2 and a pair of dashed lines connecting the circles. The first slit S1 is not limited to being formed within the region spanning the pair of welds WP1 and WP2; at least a portion of the first slit S1 may overlap the region spanning the pair of welds WP1 and WP2.

[0038] On the other hand, Figure 3 As shown, the second slit S2 is formed so as not to overlap with a region spanning the pair of welding portions WP1 and WP2. Note that the sizes of the pair of welding portions WP1 and WP2 may be different, and the welding portions WP1 and WP2 may be formed so that their respective positions are shifted relative to each other when viewed from the X-axis direction.

[0039] Figure 5 FIG is a plan view of a busbar B101 according to a comparative example. Figure 5As shown, the bus bar B101 according to the comparative example includes a pair of welding portions WP1 and WP2 and five slits S11 to S15 . Figure 5 The first slit S11 shown is Figure 3 The illustrated first slit S1 corresponds to and extends in the stacking direction (X-axis direction) in a region spanning the pair of welding portions WP1 and WP2. Figure 5 The second slit S12 is shown extending parallel to the first slit S11 outside the region spanning the pair of weld portions WP1 and WP2.

[0040] Furthermore, the busbar B101 according to the comparative example includes a third slit S13, which is disposed opposite the second slit S12 across the first slit S11 and extends parallel to the first slit S11. Furthermore, the busbar B101 according to the comparative example includes a fourth slit S14 and a fifth slit S15, which are disposed opposite the first slit S11 across the second slit S12 and extend parallel to the second slit S12.

[0041] like Figure 5 As shown, the five slits S11 to S15 formed on the bus bar B101 according to the comparative example have the same length and width. Therefore, although the bus bar B101 according to the comparative example includes a plurality of slits extending in the stacking direction (X-axis direction) and having the same width, stress acting on the pair of welded portions WP1 and WP2 cannot be sufficiently relieved.

[0042] On the other hand, in the battery cell stack CS according to the present embodiment, as Figure 3 As shown, the width of the first slit S1 formed to overlap the region spanning the pair of welding parts WP1 and WP2 is greater than the width of the second slit S2 formed outside the region spanning the pair of welding parts WP1 and WP2. Figure 3 The width of the first slit S1 is larger than that of the Figure 5 The width of the first slit S11 in the busbar B101 of the comparative example is shown.

[0043] With the above-described structure, in the battery cell stack CS according to the present embodiment, the stress acting on the welded portions WP1 and WP2 of the bus bar B1 is greater than that acting on the battery cell stack CS according to the embodiment. Figure 5 The stress of the welded portions WP1 and WP2 of the busbar B101 of the comparative example shown is more relaxed, and the fatigue life of the welded portions WP1 and WP2 is longer than that of the busbar B101 according to the comparative example. Figure 5 The fatigue life of the welded portion of the busbar B101 of the comparative example shown is further improved. It is worth noting that Figure 3 The first slit S1 shown is larger than the Figure 5The first slit S11 in the bus bar B101 of the illustrated comparative example is long.

[0044] Furthermore, if Figure 3 As shown, the second slit S2 is longer than the first slit S1, and the second slit S2 is formed to overlap with the welding parts WP1 and WP2 when viewed from the Z-axis direction. Figure 3 The second slit S2 shown is larger than the Figure 5 The second slit S12 in the busbar B101 of the comparative example shown is long. Figure 3 In the busbar B1 shown in FIG, the stress acting on the welds WP1 and WP2 of the busbar B1 is greater than that acting on the welds WP1 and WP2 according to FIG. Figure 5 The stress of the welded portions WP1 and WP2 of the busbar B101 of the comparative example shown can be more greatly relieved.

[0045] Further, in Figure 3 In the busbar B1 shown, the number of slits required is less than that according to Figure 5 The number of slits required in the busbar B101 of the comparative example shown is smaller than that in the busbar B1 occupied by the first slit S1 and the second slit S2. Figure 5 The area occupied by the slits S11 to S15 in the busbar B101 of the comparative example shown in FIG. Figure 3 In the busbar B1 shown, according to Figure 5 Compared with the bus bar B101 of the comparative example shown, the increase in resistance due to the formation of the slits can be reduced, and the heat generated when the bus bar B1 is energized can be suppressed.

[0046] In addition, if Figure 4 As shown, the busbar B1 according to this embodiment has a hat shape in the XY cross section and protrudes outward (on the negative side of the Y axis) from between the pair of welded portions WP1 and WP2. Therefore, the stress acting on the welded portions WP1 and WP2 of the busbar B1 having a hat shape can be more alleviated than when the busbar B1 has a simple flat plate shape. Note that the cross-sectional shape of the bus bar B1 is not limited to a hat shape, and may be, for example, a simple flat plate shape.

[0047] As described above, in the battery cell stack CS according to this embodiment, the width of the first slit S1 formed to overlap the region spanning the pair of welds WP1 and WP2 is greater than the width of the second slit S2 formed outside the region spanning the pair of welds WP1 and WP2. Therefore, the stress acting on the welds WP1 and WP2 of the busbar B1 is relieved, and the fatigue life of the welds WP1 and WP2 is improved.

[0048] (First modification example) Next, we will refer to Figure 6 A busbar B1 according to a first modified example will be described. Figure 6 is a plan view of a busbar B1 according to a first modification example.

[0049] like Figure 6 As shown, Figure 3 Compared with the busbar B1 shown in FIG. 1 , the busbar B1 according to the first modified example further includes a third slit S3 . The third slit S3 is disposed to face the second slit S2 across the first slit S1 and extends parallel to the first slit S1 .

[0050] Figure 6 The third slit S3 shown is consistent with the Figure 5 The third slit S13 in the busbar B101 of the comparative example shown corresponds to the third slit S13. Figure 6 The third slit S3 shown is larger than the Figure 5 The third slit S13 in the bus bar B101 of the illustrated comparative example is long.

[0051] Figure 6 The third slit S3 is shown formed between a pair of welds WP1 and WP2, however, the present disclosure is not particularly limited thereto. Notably, the width of the third slit S3 is the same as that of the second slit S2 and smaller than that of the first slit S1. By providing a third slit S3 with a width smaller than that of the first slit S1, the stress acting on the welds WP1 and WP2 of the busbar B1 can be further alleviated while suppressing heat generation due to increased resistance. Furthermore, by making the width of the third slit S3 the same as that of the second slit S2, it becomes easier to form the slit in the busbar B1.

[0052] Furthermore, if Figure 6 As shown, by making the third slit S3 longer than the first slit S1 , the stress acting on the welded portions WP1 and WP2 of the busbar B1 can be further alleviated. It is worth noting that Figure 6 As shown, the first slit S1 may be formed to protrude from a region spanning the pair of welding portions WP1 and WP2 .

[0053] As described above, the busbar B1 according to the first modified example includes the third slit S3 having a width smaller than that of the first slit S1. Therefore, the stress acting on the welded portions WP1 and WP2 of the busbar B1 can be reduced compared to the stress acting on the welded portions WP2. Figure 3 The stress of the welded portions WP1 and WP2 of the busbar B1 is shown to be more relieved while suppressing the heat generation due to the increase in electrical resistance. Structures other than the above Figure 3 and Figure 4 The structure of the bus bar B1 shown is similar, so its description will be omitted.

[0054] Other deformation examples Next, we will refer to Figure 7 and Figure 8 A busbar B1 according to another modified example will be described. Figure 7 is a plan view of a busbar B1 according to a second modification example. Figure 8 is a plan view of a busbar B1 according to a third modified example.

[0055] like Figure 7 As shown, according to Figure 6 Compared to the busbar B1 of the first modified example, the busbar B1 according to the second modified example further includes a fourth slit S4 disposed to face the first slit S1 with the second slit S2 interposed therebetween and extending in parallel with the second slit S2 .

[0056] It is worth noting that Figure 7 The fourth slit S4 shown is consistent with the Figure 5 This corresponds to the fourth slit S14 in the busbar B101 of the illustrated comparative example. Figure 7 The fourth slit S4 shown has the same Figure 5 The fourth slit S14 in the busbar B101 of the comparative example shown has the same shape. However, the present disclosure is not particularly limited thereto.

[0057] Furthermore, if Figure 8 As shown, according to Figure 6 Compared to the busbar B1 of the first modification example, the busbar B1 according to the third modification example further includes fourth and fifth slits S4 and S5 , which are arranged to face the first slit S1 with the second slit S2 interposed therebetween and extend parallel to the second slit S2 .

[0058] It is worth noting that Figure 8 The fourth slit S4 and the fifth slit S5 shown are the same as those according to Figure 5 The fourth slit S14 and the fifth slit S15 in the bus bar B101 of the illustrated comparative example correspond to each other. Figure 8 The shapes of the fourth slit S4 and the fifth slit S5 in the busbar B1 are similar to those of the Figure 5 The fourth slit S14 and the fifth slit S15 in the bus bar B101 of the illustrated comparative example have the same shape, however, the present disclosure is not particularly limited thereto.

[0059] like Figure 7 and Figure 8 As shown, according to Figure 6 The busbar B1 of the first modified example shown in FIG. 1 can further include slits. With this structure, the stress acting on the welded portions WP1 and WP2 of the busbar B1 can be reduced compared to the stress acting on the welded portions WP1 and WP2 of the busbar B1. Figure 6 The stress of the welded parts WP1 and WP2 of the busbar B1 of the first modified example shown is further relieved. At the same time, by further adding slits to the busbar B1, the resistance of the busbar B1 becomes greater than that according to the embodiment of the present invention. Figure 6 The busbar B1 of the first modified example shown is larger. Structures and bases other than the above Figure 6 The structure of the bus bar B1 of the illustrated first modified example is similar, and therefore description thereof will be omitted.

[0060] From the disclosure thus described, it is obvious that the embodiments of the present disclosure may be modified in various ways. Such variations are not to be regarded as departing from the spirit and scope of the present disclosure, and all such modifications obvious to those skilled in the art are intended to be included within the scope of the following claims.

Claims

1. A battery cell stack having a rectangular parallelepiped shape, in which a plurality of rectangular battery cells are stacked, and each of the plurality of rectangular battery cells includes a terminal provided in an end face in a longitudinal direction thereof, The battery cell stack includes a plate-shaped bus bar configured to electrically connect terminals of adjacent rectangular battery cells to each other, in, The busbar comprises: a first slit extending in the stacking direction of the rectangular battery cells so that at least a portion of the first slit overlaps a region spanning a pair of welds welded to respective terminals of the adjacent rectangular battery cells; and a second slit extending parallel to the first slit outside a region spanning the pair of welded portions, Wherein, the width of the first slit is greater than the width of the second slit.

2. The battery cell stack according to claim 1, wherein: The second slit is longer than the first slit.

3. The battery cell stack according to claim 1 or 2, further comprising a third slit, the third slit being arranged to face the second slit across the first slit and extending parallel to the first slit. in, The width of the third slit is smaller than the width of the first slit.

4. The battery cell stack according to claim 3, wherein: The third slit is longer than the first slit.

5. The battery cell stack according to claim 3, wherein: The width of the third slit is the same as the width of the second slit.

6. The battery cell stack according to claim 1 or 2, wherein: The bus bar has a hat-shaped cross section and protrudes outward from between the pair of welding portions.

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