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] This disclosure relates to a stack of battery cells. Background Technology

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

[0003] Patent document 1: U.S. Patent Application No. 2022 / 0302533 published. Utility Model Content

[0004] The inventors have discovered the following problem in battery cell stacks where each rectangular battery cell has a terminal on its longitudinal end face. In these stacks, a flat busbar is welded to each terminal of adjacent rectangular battery cells, thereby electrically connecting the terminals of adjacent rectangular battery cells to each other. In, for example, in automotive battery cell stacks, stress is repeatedly applied to the welded portion of the busbar due to the vertical movement of the vehicle.

[0005] This disclosure is made in view of the above circumstances, and provides a battery cell stack that can alleviate the stress acting on the welded portion of the busbar and improve the fatigue life of the welded portion.

[0006] According to one aspect of this disclosure, a battery cell stack has a cuboid shape, with a plurality of rectangular battery cells stacked in the battery cell stack, and each of the plurality of rectangular battery cells includes a terminal disposed in an end face in its longitudinal direction.

[0007] The battery cell stack includes a plate-shaped busbar configured to electrically connect the terminals of adjacent rectangular battery cells to each other.

[0008] The busbars include:

[0009] A first slit extending in the stacking direction of the rectangular battery cells such that at least a portion of the first slit overlaps with an area spanning a pair of welded portions welded to the respective terminals of adjacent rectangular battery cells; and

[0010] The second slit extends parallel to the first slit outside the area spanning the welded joint.

[0011] The width of the first slit is greater than the width of the second slit.

[0012] In the battery cell stack according to this disclosure, the plate-shaped busbar electrically connecting the terminals of adjacent rectangular battery cells to each other 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 with a region spanning a pair of welded portions welded to the respective terminals of the adjacent rectangular battery cells; and a second slit extending parallel to the first slit outside the region spanning the pair of welded portions. Further, the width of the first slit is greater than the width of the second slit.

[0013] With the above structure, the stress acting on the welded part of the busbar can be relieved, and the fatigue life of the welded part can be improved.

[0014] The second slit can be longer than the first slit. With the above structure, the stress acting on the welded part of the busbar can be further relieved, and the fatigue life of the welded part can be further improved.

[0015] The battery cell stack may also include a third slit, which is configured to face the second slit across the first slit and extend parallel to the first slit, wherein the width of the third slit may be smaller than the width of the first slit. With the above structure, while suppressing the heat generated when the busbar is energized, the stress acting on the welded portion of the busbar can be further alleviated, and the fatigue strength of the welded portion can be further improved.

[0016] The third slit can be longer than the first slit. With the above structure, the stress acting on the welded part of the busbar can be further relieved, and the fatigue strength of the welded part can be further improved.

[0017] The width of the third slit can be the same as the width of the second slit. The above structure can easily form slits in the busbar.

[0018] The busbar has a cap-shaped cross-section and can protrude outward from between the pair of welded parts. With the above structure, the stress acting on the welded parts of the busbar can be further relieved, and the fatigue life of the welded parts can be further improved.

[0019] According to this disclosure, a battery cell stack can be provided that can alleviate the stress acting on the welded portion of the busbar and improve the fatigue life of the welded portion.

[0020] The above and other objects, features and advantages of this disclosure will be more fully understood from the detailed description and accompanying drawings given below. Attached Figure Description

[0021] Figure 1 This is a perspective view showing a battery cell stack according to the first embodiment;

[0022] Figure 2This is a perspective view showing a battery cell stack according to the first embodiment;

[0023] Figure 3 This is a plan view of busbar B1;

[0024] Figure 4 It is along Figure 3 A cross-sectional view taken by cutting line IV-IV;

[0025] Figure 5 It is a plan view based on busbar B101 in the comparative example;

[0026] Figure 6 It is a plan view based on the generatrix B1 of the first variant example;

[0027] Figure 7 It is a plan view based on the second modified example of generatrix B1; and

[0028] Figure 8 It is a plan view of the generatrix B1 based on the third variation example. Detailed Implementation

[0029] Specific embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. However, the present disclosure is not limited to the following embodiments. Furthermore, for clarity, the following description and drawings will be appropriately simplified.

[0030] (First Embodiment)

[0031] <Structure of Battery Cell Stack>

[0032] 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 these is a perspective view showing a battery cell stack according to the first embodiment.

[0033] It is worth noting, without a doubt, Figure 1 and Figure 2 The right-handed XYZ Cartesian coordinate system shown in the other accompanying figures is merely for the convenience of explaining the positional relationships between components. Typically, in... Figure 1 , Figure 2 In the diagram, the positive Z-axis is the vertical upward direction, and the XY plane is the horizontal plane, with the direction and plane running through the entire diagram being the same.

[0034] like Figure 1 and Figure 2 As shown, the battery cell stack CS according to this embodiment includes rectangular battery cells C1 to C6 and busbars B1 to B5.

[0035] The battery cell stack CS according to this embodiment is used, for example, in an on-board battery. The vehicle on 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 that can be driven by electricity supplied from the battery cell stack CS, such as a pure electric vehicle, a hybrid electric vehicle, and a fuel cell electric vehicle.

[0036] like Figure 1 and Figure 2 As shown, rectangular battery cells C1 to C6 are cuboid rectangular 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.

[0037] It is worth noting that, in Figure 1 and Figure 2 In the diagram, the battery cell stack CS is shown in a simplified manner. Although Figure 1 and Figure 2 The battery cell stack CS shown is formed by six rectangular battery cells C1 to C6, but it is usually formed by more rectangular battery cells. In fact, the number of rectangular battery cells forming the battery cell stack CS is not limited to any specific number, and can be any number of more than two. Furthermore, heat insulation plates, spacers for adjusting the spacing, etc. (not shown) can be inserted between adjacent rectangular battery cells.

[0038] like Figure 1 As shown, the rectangular battery cell C1 has a positive terminal PT1 on one end face in the longitudinal direction (the end face on the negative side of the Y-axis). Figure 1 The positive terminal PT1 shown has a rectangular shape in the XZ plane and is designed to protrude outward from the end face of the rectangular battery cell C1. However, this disclosure is not particularly limited to this. Furthermore, a [missing information - likely a typology or feature] is provided on the upper side (positive Z-axis side) of the end face of the rectangular battery cell C1. Figure 1 The positive terminal PT1 is shown. The positive terminal PT1 is made of, for example, a metallic material with excellent electrical conductivity, such as copper.

[0039] Similarly, such as Figure 1As shown, rectangular battery cell C2, adjacent to rectangular battery cell C1, has a negative terminal NT2 on one end face in the longitudinal direction (the end face on the negative Y-axis). Rectangular battery cell C3, adjacent to rectangular battery cell C2, has a positive terminal PT3 on one end face in the longitudinal direction (the end face on the negative Y-axis). Rectangular battery cell C4, adjacent to rectangular battery cell C3, has a negative terminal NT4 on one end face in the longitudinal direction (the end face on the negative Y-axis). Rectangular battery cell C5, adjacent to rectangular battery cell C4, has a positive terminal PT5 on one end face in the longitudinal direction (the end face on the negative Y-axis). Rectangular battery cell C6, adjacent to rectangular battery cell C5, has a negative terminal NT6 on one end face in the longitudinal direction (the end face on the negative Y-axis).

[0040] like Figure 1 As shown, each of the negative terminal NT2 of rectangular battery cell C2, the positive terminal PT3 of rectangular battery cell C3, the negative terminal NT4 of rectangular battery cell C4, the positive terminal PT5 of rectangular battery cell C5, and the negative terminal NT6 of rectangular battery cell C6 has a shape similar to that of the positive terminal PT1 of rectangular battery cell C1, and is arranged in a manner similar to that of the positive terminal PT1 of rectangular battery cell C1.

[0041] Furthermore, such as Figure 1 As shown, the positive terminal PT1 of rectangular battery cell C1 and the negative terminal NT2 of rectangular battery cell C2, which are arranged adjacent to each other, are electrically connected to each other via a plate-shaped busbar B1. Similarly, the positive terminal PT3 of rectangular battery cell C3 and the negative terminal NT4 of rectangular battery cell C4, which are arranged adjacent to each other, are electrically connected to each other via a plate-shaped busbar B3. Similarly, the positive terminal PT5 of rectangular battery cell C5 and the negative terminal NT6 of rectangular battery cell C6, which are arranged adjacent to each other, are electrically connected via a plate-shaped busbar B5.

[0042] At the same time, such as Figure 2 As shown, the rectangular battery cell C1 has a negative terminal NT1 on its other end face (the end face on the positive side of the Y-axis) in the longitudinal direction. Like Figure 1 As shown in the diagram, the positive terminal PT1, Figure 2 The negative terminal NT1 shown has a rectangular shape in the XZ plane diagram and is configured to protrude outward from the end face of the rectangular battery cell C1. However, this disclosure is not particularly limited to this. Further, like... Figure 1 As shown in the diagram, the positive terminal PT1 has a [missing information - likely a component or part] on the upper side (positive Z-axis 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 metallic material such as copper, which has excellent electrical conductivity.

[0043] Similarly, such as Figure 2 As shown, rectangular battery cell C2, adjacent to rectangular battery cell C1, has a positive terminal PT2 on its other end face (the end face on the positive Y-axis side) in the longitudinal direction. Rectangular battery cell C3, adjacent to rectangular battery cell C2, has a negative terminal NT3 on its other end face (the end face on the positive Y-axis side) in the longitudinal direction. Rectangular battery cell C4, adjacent to rectangular battery cell C3, has a positive terminal PT4 on its other end face (the end face on the positive Y-axis side) in the longitudinal direction. Rectangular battery cell C5, adjacent to rectangular battery cell C4, has a negative terminal NT5 on its other end face (the end face on the positive Y-axis side) in the longitudinal direction. Rectangular battery cell C6, adjacent to rectangular battery cell C5, has a positive terminal PT6 on its other end face (the end face on the positive Y-axis side) in the longitudinal direction.

[0044] like Figure 2 As shown, each of the positive terminal PT2 of rectangular battery cell C2, the negative terminal NT3 of rectangular battery cell C3, the positive terminal PT4 of rectangular battery cell C4, the negative terminal NT5 of rectangular battery cell C5, and the positive terminal PT6 of rectangular battery cell C6 has a shape similar to that of the negative terminal NT1 of rectangular battery cell C1, and is arranged in a similar manner to that of the negative terminal NT1 of rectangular battery cell C1.

[0045] Furthermore, such as Figure 2 As shown, the positive terminal PT2 of rectangular battery cell C2 and the negative terminal NT3 of rectangular battery cell C3, which are arranged adjacent to each other, are electrically connected to each other via a plate-shaped busbar B2. Similarly, the positive terminal PT4 of rectangular battery cell C4 and the negative terminal NT5 of rectangular battery cell C5, which are arranged adjacent to each other, are electrically connected to each other via a plate-shaped busbar B4. As described above, in Figure 1 and Figure 2 In the battery cell stack CS shown, rectangular battery cells C1 to C6 are connected in series with each other via busbars B1 to B5.

[0046] 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 via, for example, a bus (not shown). However, this disclosure is not particularly limited to this. Further, Figure 2 The positive terminal PT6 of the rectangular battery cell C6 shown is connected to the negative terminal of another battery cell stack via, for example, a bus (not shown). However, this disclosure is not particularly limited to this. With the above structure, for example, multiple battery cell stacks can be connected in series with each other.

[0047] because Figure 1 and Figure 2The busbars B1 to B5 shown have similar structures to each other, so busbar B1 will be described.

[0048] like Figure 1 As shown, busbar B1 is a plate-like component that electrically connects the positive terminal PT1 of rectangular battery cell C1, which is positioned adjacent to each other, to the negative terminal NT2 of rectangular battery cell C2. Busbar B1 is made of, for example, a metallic material with excellent conductivity, such as copper.

[0049] like Figure 1 As shown, busbar B1 includes a pair of welded portions WP1 and WP2, which are welded to the positive terminal PT1 of rectangular battery cell C1 and the negative terminal NT2 of rectangular battery cell C2, respectively, which are arranged adjacent to each other. Busbar B1 includes a first slit S1 and a second slit S2. The first slit S1 extends in the stacking direction (X-axis direction) to overlap with the area spanning the pair of welded portions WP1 and WP2. The second slit S2 extends parallel to the first slit S1 outside the area spanning the pair of welded portions WP1 and WP2. Notably, the width of the first slit S1 is greater than the width of the second slit S2.

[0050] As described above, in the battery cell stack CS according to this embodiment, the width of the first slit S1, which overlaps with the region spanning the pair of welded portions WP1 and WP2, is greater than the width of the second slit S2, which is formed outside the region spanning the pair of welded portions WP1 and WP2. Therefore, the stress acting on the welded portions WP1 and WP2 of the busbar B1 is relieved, and the fatigue life of the welded portions WP1 and WP2 is improved.

[0051] <Detailed Structure of the Busbar>

[0052] The following will refer to Figure 3 and Figure 4 Describe the detailed structure of busbar B1. Figure 3 This is a plan view of busbar B1. Figure 4 It is along Figure 3 The cross-sectional view taken by the cutting line IV-IV.

[0053] It is worth noting that, Figure 3 and Figure 4 The positive terminal PT1 of rectangular battery cell C1 and the negative terminal NT2 of rectangular battery cell C2 are also shown. Furthermore, Figure 3 Although it is a plan view, the busbar B1 is represented by a dotted pattern for easier understanding.

[0054] like Figure 3As shown, busbar B1 is a plate-like member with a rectangular shape in the XZ plan view. Busbar B1 is configured to substantially cover the entire positive terminal PT1 of rectangular battery cell C1 and the entire negative terminal NT2 of 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 rectangular battery cell C1 and the negative terminal NT2 of rectangular battery cell C2, which are arranged adjacent to each other.

[0055] It is worth noting that, Figure 3 and Figure 4 The welding portions WP1 and WP2 before welding are shown. For example, by irradiating the welding portion WP1 with a laser beam from the negative Y-axis side, the busbar B1 is welded to the positive terminal PT1 of the rectangular battery cell C1 in the welding portion WP1. However, this disclosure is not particularly limited to this. Similarly, by irradiating the welding portion WP2 with a laser beam from the negative Y-axis side, the busbar B1 is welded to the negative terminal NT2 of the rectangular battery cell C2 in the welding portion WP2.

[0056] Figure 3 The welded portions WP1 and WP2 shown are located at each end of the busbar B1 on its lower side (negative side of the Z-axis) in the X-axis direction. However, this disclosure is not particularly limited thereto. Figure 3 and Figure 4 Each of the welded portions WP1 and WP2 shown has a circular shape in the XZ plane view and includes a through hole in its center. However, this disclosure is not particularly limited thereto. Further, as Figure 4 As shown, each of the welded sections WP1 and WP2 is counterbored, and its plate thickness is less than that of other areas of busbar B1.

[0057] It is worth noting that, such as Figure 3 As shown, the first slit S1 extends in the stacking direction (X-axis direction) within the region spanning a 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 the width of the second slit S2.

[0058] It is worth noting that, in Figure 3 In the diagram, the region spanning the welded portions WP1 and WP2 is the area enclosed by a circle defining the outer edges of the welded portions WP1 and WP2 and a pair of dashed lines connecting the circles. The first slit S1 is not limited to being formed in the region spanning the welded portions WP1 and WP2, but may also be formed such that at least a portion of the first slit S1 overlaps with the region spanning the welded portions WP1 and WP2.

[0059] On the other hand, such as Figure 3As shown, the second slit S2 is formed so as not to overlap with the area spanning the pair of welded portions WP1 and WP2.

[0060] It is worth noting that the dimensions of the welded parts WP1 and WP2 can be different, and the welded parts WP1 and WP2 can be configured such that their respective positions are offset relative to each other when viewed from the X-axis direction.

[0061] Figure 5 This is based on the plan view of busbar B101 in the comparative example. For example... Figure 5 As shown, the busbar B101 according to the comparative example includes a pair of welded sections WP1 and WP2 and five slits S11 to S15. Figure 5 The first slit S11 shown is... Figure 3 The first slit S1 shown corresponds to and extends in the stacking direction (X-axis direction) in the region spanning the pair of welded portions WP1 and WP2. Figure 5 The second slit S12 shown extends parallel to the first slit S11 outside the area spanning the welded portions WP1 and WP2.

[0062] Furthermore, according to the comparative example, busbar B101 includes a third slit S13, which is configured to face the second slit S12 across the first slit S11 and extend parallel to the first slit S11. Furthermore, according to the comparative example, busbar B101 includes a fourth slit S14 and a fifth slit S15, which are configured to face the first slit S11 across the second slit S12 and extend parallel to the second slit S12.

[0063] like Figure 5 As shown, the five slits S11 to S15 formed on the busbar B101 according to the comparative example have the same length and width.

[0064] Therefore, although the busbar B101 according to the comparative example includes multiple slits extending in the stacking direction (X-axis direction) and having the same width, the stress acting on the welded portions WP1 and WP2 cannot be adequately relieved.

[0065] On the other hand, in the battery cell stack CS according to this embodiment, such as Figure 3 As shown, the width of the first slit S1, which overlaps with the region spanning the welded portions WP1 and WP2, is greater than the width of the second slit S2, which is formed outside the region spanning the welded portions WP1 and WP2. That is, it makes... Figure 3 The width of the first slit S1 shown is greater than according to Figure 5 The width of the first slit S11 within busbar B101 in the comparative example shown.

[0066] With the above structure, in the battery cell stack CS according to this embodiment, the stress ratio acting on the welded portions WP1 and WP2 of the busbar B1 is equal to the stress acting on the battery cell stack CS according to this embodiment. Figure 5 In the comparative example shown, the stress at welds WP1 and WP2 of busbar B101 is greatly relieved, and the fatigue life of welds WP1 and WP2 is longer than that of the welds shown. Figure 5 The fatigue life of the welded portion of busbar B101 in the comparative example shown is further improved.

[0067] It is worth noting that, Figure 3 The first slit S1 shown is according to Figure 5 The length of the first slit S11 in the busbar B101 shown in the comparative example is [length missing].

[0068] Furthermore, such as 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 welded portions WP1 and WP2 when viewed from the Z-axis direction. That is, Figure 3 The second slit S2 shown is according to Figure 5 The second slit S12 in the busbar B101 of the comparative example shown is long. Through this structure, in... Figure 3 In the busbar B1 shown, the stress ratio acting on the welded portions WP1 and WP2 of busbar B1 is as follows: Figure 5 The stress at the welded portions WP1 and WP2 of busbar B101 in the comparative example shown can be greatly relieved.

[0069] Furthermore, in Figure 3 In the busbar B1 shown, the required number of slits is less than according to Figure 5 The comparison example shown illustrates the required number of slits in busbar B101, and the area occupied by the first slit S1 and the second slit S2 in busbar B1 is smaller than that according to... Figure 5 The comparative example shown illustrates the area occupied by slits S11 to S15 in busbar B101. Therefore, in Figure 3 In the busbar B1 shown, according to Figure 5 Compared to the busbar B101 in the comparative example shown, the increase in resistance due to the formation of the slit can be reduced, and the heat generated when the busbar B1 is energized can be suppressed.

[0070] In addition, such as Figure 4 As shown, according to this embodiment, the busbar B1 has a hat shape in the XY 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 with the hat shape can be greatly alleviated compared to the case where the busbar B1 has a simple flat plate shape.

[0071] It is worth noting that the cross-sectional shape of busbar B1 is not limited to a cap shape, and can be, for example, a simple flat plate shape.

[0072] As described above, in the battery cell stack CS according to this embodiment, the width of the first slit S1, which overlaps with the region spanning the pair of welded portions WP1 and WP2, is greater than the width of the second slit S2, which is formed outside the region spanning the pair of welded portions WP1 and WP2. Therefore, the stress acting on the welded portions WP1 and WP2 of the busbar B1 is relieved, and the fatigue life of the welded portions WP1 and WP2 is improved.

[0073] (Example of the first variation)

[0074] Next, we will refer to Figure 6 The busbar B1 according to the first variation example is described. Figure 6 It is a plan view of the busbar B1 based on the first variation example.

[0075] like Figure 6 As shown, with Figure 3 Compared to the busbar B1 shown, the busbar B1 according to the first modified example also includes a third slit S3, which is configured to face the second slit S2 across the first slit S1 and extend parallel to the first slit S1.

[0076] Figure 6 The third slit S3 shown is based on Figure 5 The third slit S13 in busbar B101 of the comparative example shown corresponds to this. It is worth noting that... Figure 6 The third slit S3 shown is according to Figure 5 The length of the third slit S13 in busbar B101 in the comparative example shown is [length missing].

[0077] Figure 6 The third slit S3 shown is formed between a pair of welded portions WP1 and WP2; however, this disclosure is not particularly limited thereto. It is noteworthy that the width of the third slit S3 is the same as the width of the second slit S2 and smaller than the width of the first slit S1. By providing a third slit S3 with a width smaller than the first slit S1, the stress acting on the welded portions WP1 and WP2 of busbar B1 can be further alleviated, while suppressing heat generated due to increased resistance. Furthermore, by making the width of the third slit S3 the same as the width of the second slit S2, it becomes easier to form a slit in busbar B1.

[0078] Furthermore, such as 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 busbar B1 can be further relieved.

[0079] It is worth noting that, such as Figure 6 As shown, the first slit S1 can be formed to protrude from the area spanning the pair of welded portions WP1 and WP2.

[0080] As described above, according to the first modified example, busbar B1 includes a third slit S3 with a width smaller than that of the first slit S1. Therefore, the stress acting on the welded portions WP1 and WP2 of busbar B1 is greater than that acting on the welded portions of the first slit S1. Figure 3 The stress at the welded portions WP1 and WP2 of busbar B1 shown is greatly relieved, while the heat generated due to increased resistance is suppressed.

[0081] Other structures and Figure 3 and Figure 4 The structure of busbar B1 shown is similar, so its description will be omitted.

[0082] Other examples of deformation

[0083] Next, we will refer to Figure 7 and Figure 8 The busbar B1, based on other variations, is described. Figure 7 It is a plan view of the busbar B1 based on the second variation example. Figure 8 It is a plan view of the generatrix B1 based on the third variation example.

[0084] like Figure 7 As shown, and according to Figure 6 Compared to the first variant example shown, the second variant example of the busbar B1 further includes a fourth slit S4, which is configured to face the first slit S1 across the second slit S2 and extend parallel to the second slit S2.

[0085] It is worth noting that, Figure 7 The fourth slit S4 shown is based on Figure 5 The fourth slit S14 in busbar B101 of the comparative example shown corresponds to this. Figure 7 The fourth slit S4 shown has the same characteristics as according to Figure 5 The fourth slit S14 in the busbar B101 of the comparative example shown has the same shape. However, this disclosure is not particularly limited thereto.

[0086] Furthermore, such as Figure 8 As shown, and according to Figure 6 Compared to the first variant example shown, the third variant example of the busbar B1 further includes a fourth slit S4 and a fifth slit S5, which are configured to face the first slit S1 across the second slit S2 and extend parallel to the second slit S2.

[0087] It is worth noting that, Figure 8The fourth slit S4 and the fifth slit S5 shown are in accordance with... Figure 5 The fourth slit S14 and the fifth slit S15 in the busbar B101 of the comparative example shown correspond to each other. Figure 8 The shapes of the fourth slit S4 and the fifth slit S5 in the busbar B1 shown are according to... Figure 5 The fourth slit S14 and the fifth slit S15 in the busbar B101 of the comparative example shown have the same shape; however, this disclosure is not particularly limited thereto.

[0088] like Figure 7 and Figure 8 As shown, according to Figure 6 The slits can be further increased on busbar B1 in the first modified example shown. With this structure, the stress acting on the welded portions WP1 and WP2 of busbar B1 can be reduced compared to the stress acting on the welded portions according to the... Figure 6 In the first modified example shown, the stress at the welded portions WP1 and WP2 of busbar B1 is significantly reduced. Simultaneously, by further increasing the slits on busbar B1, the resistance of busbar B1 becomes greater than according to... Figure 6 The first variant example shown has a larger busbar B1.

[0089] Other structures and bases mentioned above Figure 6 The structure of the busbar B1 in the first variant example shown is similar, so its description will be omitted.

[0090] As will be apparent from the disclosure described herein, embodiments of this disclosure can be modified in a variety of ways. Such modifications should not be considered as departing from the spirit and scope of this disclosure, and all such modifications that will be apparent 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 cuboid shape, a plurality of rectangular battery cells stacked in the battery cell stack, and each of the plurality of rectangular battery cells including a terminal provided in an end surface in a longitudinal direction thereof, the battery cell stack including a plate-shaped busbar configured to electrically connect terminals of adjacent rectangular battery cells to each other, wherein the busbar including: a first slit extending in a stacking direction of the rectangular battery cells so that at least a portion of the first slit overlaps with a region across a pair of welds welded to respective terminals of the adjacent rectangular battery cells; and a second slit extending in parallel with the first slit outside the region across the pair of welds, wherein a width of the first slit is greater than a width of the second slit.

2. The battery cell stack of 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 provided to face the second slit across the first slit and extending in parallel with the first slit, wherein a width of the third slit is smaller than the width of the first slit.

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

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

6. The battery cell stack of claim 1 or 2, wherein, the busbar has a hat-shaped cross section and protrudes outward from between the pair of welds.

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