Battery pack and cell series connection element thereof

Abstract

To provide a cell series connection element.SOLUTION: A cell series connection element includes a multi-layer structure and two fixing members. The multi-layer structure includes a plurality of metal sheets arranged in a stack, with a gap between any two adjacent metal sheets. The two fixing members are used to clamp and fix both ends of the multi-layer structure, and are electrically connected to the electrode terminals of the cells, respectively.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a battery pack and its cell series connection elements. [Background technology]

[0002] In the past, multiple cells in a battery pack were connected in series using a flat metal plate. When the battery pack was in operation, not only did the cells heat up, but the flat metal plate also heated up due to the flow of current. This could further increase the temperature of the cells, posing a safety concern. Summary of the Invention [Problem to be solved by the invention]

[0003] In view of this, an object of the present disclosure is to propose an improved battery pack and cell series-connection element to solve the above-mentioned problems of the prior art. [Means for solving the problem]

[0004] According to some embodiments of the present disclosure, a cell series connection element includes a multilayer structure including a plurality of stacked first metal sheets with a gap between any two adjacent first metal sheets, and two fixing members for fixing and clamping both ends of the multilayer structure and electrically connecting each to an electrode terminal of a cell.

[0005] In one or more embodiments of the present disclosure, the fixing member includes a second metal sheet, the second metal sheet being folded to form a recess, and an end of the first metal sheet being inserted into the recess.

[0006] In one or more embodiments of the present disclosure, the thickness of the second metal sheet is greater than the thickness of each of the first metal sheets.

[0007] In one or more embodiments of the present disclosure, the hardness of the material of the second metal sheet is greater than the hardness of the material of each of the first metal sheets.

[0008] In one or more embodiments of the present disclosure, each first metal sheet includes a first planar segment, a second planar segment, and an intermediate segment. The first planar segment and the second planar segment are separated from each other, the intermediate segment is located between the first planar segment and the second planar segment, and the first planar segment and the second planar segment have different heights. Two fixing members clamp the first planar segment and the second planar segment, respectively.

[0009] In one or more embodiments of the present disclosure, each first metal sheet further includes a first beveled segment and a second beveled segment, the first beveled segment being connected between the first flat segment and the intermediate segment, and the second beveled segment being connected between the second flat segment and the intermediate segment. The first metal sheets are bent one by one at the first beveled segment and the second beveled segment so as to form a gap in the intermediate segments of any two adjacent first metal sheets.

[0010] In one or more embodiments of the present disclosure, the first metal sheet includes adjacent third and fourth metal sheets, the third metal sheet including an intermediate segment, and the fourth metal sheet having a notch and a folding edge extending from an edge of the notch, the folding edge being folded toward the third metal sheet and abutting against the intermediate segment of the third metal sheet.

[0011] In one or more embodiments of the present disclosure, the first metal sheet includes adjacent third and fourth metal sheets, the third metal sheet including a planar region, and the fourth metal sheet including a bent portion, the bent portion protruding toward the third metal sheet and abutting the planar region of the third metal sheet.

[0012] In one or more embodiments of the present disclosure, the first metal sheet includes adjacent third and fourth metal sheets, the third metal sheet is positioned below the fourth metal sheet, the ends of the third and fourth metal sheets are overlapped, and the length of the third metal sheet is shorter than the length of the fourth metal sheet.

[0013] According to some embodiments of the present disclosure, a battery pack includes: a housing; a plurality of cells provided within the housing, each including a positive terminal and a negative terminal, and arranged in at least one row along one direction, such that in the direction in which the cells are arranged, the positive terminals of cells located in the same row are aligned with each other and the negative terminals of cells located in the same row are aligned with each other; and a plurality of cell series-connection elements each including a multilayer structure and two fixing members, wherein the multilayer structure includes a plurality of first metal sheets arranged in a stack, with a gap between any two adjacent first metal sheets, and the two fixing members fix and sandwich both ends of the multilayer structure, and the plurality of cell series-connection elements are electrically connected to the positive terminals and the negative terminals of two adjacent cells, respectively.

[0014] In one or more embodiments of the present disclosure, the housing has a first side opening and a second side opening, the first side opening and the second side opening being provided on opposite sides of the housing and facing the cell series-connected element. [Effects of the Invention]

[0015] As described above, the present disclosure provides a cell series connection element for connecting multiple cells in series in a battery pack, the cell series connection element having a multi-layer structure including multiple stacked metal sheets with a gap between any two adjacent metal sheets. The multi-layer structure can prevent overheating of the cell series connection element itself, and can also serve as a heat sink coupled to the cells of the cell series connection element to help cool the heated cells. [Brief explanation of the drawings]

[0016] To make the above and other objects, features, advantages and embodiments of the present disclosure more clearly and comprehensibly, the accompanying drawings are described as follows: [Figure 1] FIG. 1 is a perspective view of an energy storage cabinet according to one embodiment of the present disclosure. [Figure 2] FIG. 2 is a perspective view of one battery pack of the energy storage cabinet shown in FIG. 1. [Figure 3] 3 is a plan view of the battery pack shown in FIG. 2, with the battery pack in a state where the cell series-connected element is removed. [Figure 4] FIG. 3 is an enlarged view of a cell series-connected element of the battery pack shown in FIG. 2. [Figure 5] FIG. 5 is a partially enlarged side view of the cell series-connected element shown in FIG. [Figure 6] FIG. 3 is an enlarged view of the cell series-connected elements and cells of the portion of the battery pack shown in FIG. 2. [Figure 7] FIG. 10 is a perspective view of a cell series-connected element according to another embodiment of the present disclosure. [Figure 8] FIG. 10 is a perspective view of a cell series-connected element according to another embodiment of the present disclosure. [Figure 9] FIG. 10 is a side schematic view of a cell series-connected element according to another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0017] For a more detailed and complete description of the present disclosure, reference can be made to the accompanying drawings and various embodiments described below. Each element in the drawings is not drawn to scale and is provided only to explain the present disclosure. In the following, many practical details are described to provide a complete understanding of the present disclosure, but these details are not used to limit the present disclosure, because it should be understood that a person skilled in the art can practice the present disclosure without one or more practical details.

[0018] Please refer to FIG. 1. FIG. 1 is a perspective view of an energy storage cabinet 20 according to one embodiment of the present disclosure. The energy storage cabinet 20 includes a bracket 22 and one or more battery packs 21 mounted on the bracket 22. The bracket 22 is used to mount the battery packs 21. The bracket 22 has one or more slots, each of which is used to accommodate one battery pack 21. The battery packs 21 are removably mounted in the slots of the bracket 22, i.e., the battery packs 21 can be inserted into the slots and removed from the slots as needed (e.g., when repair or maintenance is required). The battery packs 21 are connected to a slide rail structure (not shown) of the bracket 22 so that they can slide into and out of the slots.

[0019] As shown in FIG. 1 , multiple battery packs 21 are stacked vertically. The multiple battery packs 21 can be divided into multiple floor assemblies 23, and battery packs 21 located on the same horizontal floor belong to the same floor assembly 23. In the illustrated embodiment, the energy storage cabinet 20 includes nine floor assemblies 23, with one floor assembly 23 indicated by a dashed frame in the figure. The multiple battery packs 21 in each floor assembly 23 are connected in series so that the voltages of the multiple battery packs 21 in the floor assembly 23 can be added together to output a larger voltage. Each floor assembly 23 may include one common anode and one common negative electrode.

[0020] 1, the energy storage cabinet 20 further includes a junction device 26, which is mounted on the bracket 22 and located on one side of the energy storage cabinet 20, and is connected to the common positive and negative electrodes (not shown) of each layer assembly 23. The junction device 26 includes a DC junction unit, an AC auxiliary unit, and one or more control units (or one or more switch units).

[0021] 1 , the energy storage cabinet 20 further includes a cooling device 28, which is mounted on the bracket 22 and located on the other side of the energy storage cabinet 20. The cooling device 28 is used to output cool air to help cool the battery pack 21. The cooling device 28 is, for example, an air conditioning system. In some embodiments, the connection device 26 and the cooling device 28 are provided on opposite sides of the battery pack 21.

[0022] Please refer to Figure 2. Figure 2 is a perspective view of one battery pack 21 of the energy storage cabinet 20 shown in Figure 1. In Figure 2, the top cover of the battery pack 21 has been removed to illustrate the elements. The battery pack 21 includes a housing 29 and a plurality of cells 12 provided in the housing 29. The cells 12 are, for example, lithium batteries. The cells 12 may be prismatic cells or pouch-type cells. The cells 12 are arranged in at least one row along direction D, and in the embodiment shown, the battery pack 21 includes 48 cells 12 arranged in four rows of 12 cells per row.

[0023] As shown in FIG. 2 , each cell 12 includes two electrode terminals 15 arranged in parallel, including one positive terminal 13 and one negative terminal 14. The battery pack 21 further includes a plurality of first cell series-connection elements 30, also called busbar elements, which are provided within a housing 29 and configured to be connected in series to the cells 12. Specifically, the first cell series-connection element 30 is electrically connected to the positive terminals 13 and negative terminals 14 of two adjacent cells 12 located in the same row. In some embodiments, the battery pack 21 further includes at least one second cell series-connection element 40, which is provided within the housing 29 and electrically connected to the electrode terminals 15 of the cells 12 in two adjacent rows.

[0024] In the embodiment shown, the electrode terminal 15 of the cell 12 is located at the top of the cell 12, and the first cell series connection element 30 and the second cell series connection element 40 are provided above the cell 12 and are in contact with the electrode terminal 15 of the cell 12. The first cell series connection element 30 and the second cell series connection element 40 may be made of a conductive material, such as copper or a copper alloy. The first cell series connection element 30 and the second cell series connection element 40 may be fixed to the electrode terminal 15 of the cell 12 by, for example, laser welding or screwing. In some embodiments, the length of the second cell series connection element 40 is shorter than the length of the first cell series connection element 30.

[0025] As shown in FIG. 2 , each first cell series-connection element 30 includes a multilayer structure 31 and two fixing members 32. The multilayer structure 31 has one or more gaps, and the two fixing members 32 clamp and secure both ends of the multilayer structure 31, electrically connecting them to the electrode terminals 15 of two different cells 12. One fixing member 32 of the first cell series-connection element 30 is connected to the positive terminal 13 of one cell 12, and the other fixing member 32 is connected to the negative terminal 14 of the other cell 12. The multilayer structure 31 not only allows current to flow through the cells 12 but also has a heat dissipation function. Specifically, the multilayer design of the multilayer structure 31 provides an increased surface area, allowing for rapid dissipation of thermal energy. The installation of the multilayer structure 31 not only prevents overheating of the first cell series-connection element 30 itself, but also serves as a heat sink coupled to the cells 12 of the first cell series-connection element 30, helping to cool the heated cells 12. In some embodiments, the second cell series-connected element 40 also includes a multi-layer structure and two fixing members, and its structure is similar to the multi-layer structure 31 and two fixing members 32 of the first cell series-connected element 30.

[0026] As shown in FIG. 2 , the housing 29 of the battery pack 21 has at least one first side opening 41 and at least one second side opening 42. The first side opening 41 and the second side opening 42 are provided on opposite sides of the housing 29 and face the first cell series-connected element 30. In some embodiments, the housing 29 includes two opposing side walls, and the first side opening 41 and the second side opening 42 are opened in the two opposing side walls of the housing 29, respectively. The upper edges of the first side opening 41 and the second side opening 42 are located on the top surfaces of the cells 12 (i.e., the surfaces of the cells 12 on which the electrode terminals 15 are installed). The first side opening 41 and the second side opening 42 can be used to allow airflow (e.g., cool air generated by the cooling device 28 shown in FIG. 1 ) to pass through. That is, the heights of the first side opening 41 and the second side opening 42 are close to the height of the first cell series-connected element 30. For example, airflow can enter the housing 29 through the first side opening 41, pass over the cells 12, pass through the multilayer structure 31 of the first cell series-connected element 30, and leave the housing 29 through the second side opening 42, thereby improving heat dissipation efficiency through convection.

[0027] In some embodiments, the energy storage cabinet 20 has a fire-fighting mechanism to respond to situations in which a cell 12 fails, causing a temperature outburst or fire. The energy storage cabinet 20 is configured to inject a cooling liquid (e.g., pure water) into the housing 29 of the battery pack 21 when it measures overheating of the battery pack 21. At least one of the first side opening 41 and the second side opening 42 can serve as an outlet for excess cooling liquid. As shown in FIG. 2 , in some embodiments, the lower edge of at least one of the first side opening 41 and the second side opening 42 is lower than the electrode terminals 15 of the cells 12. In this way, when the cooling liquid is injected into the housing 29, the maximum liquid level of the cooling liquid is lower than the electrode terminals 15 of the cells 12, preventing the cooling liquid from contacting the electrode terminals 15.

[0028] Please refer to FIG. 3. FIG. 3 is a plan view of the battery pack 21 shown in FIG. 2, showing the battery pack 21 in a state where the first cell series-connection element 30 has been removed. Please also refer to FIGS. 2 and 3. In the direction D in which the cells 12 are arranged, the positive terminals 13 of the cells 12 located in the same column are aligned with each other, and the negative terminals 14 of the cells 12 located in the same column are aligned with each other. That is, the same electrodes of the cells 12 in the same column are located on the same side. As described above, the first cell series-connection element 30 shown in FIG. 2 is connected to the positive terminal 13 of one cell 12 and the negative terminal 14 of the other cell 12. Therefore, each first cell series-connection element 30 extends at an incline in the direction D in which the cells 12 are arranged, and the first cell series-connection elements 30 located in the same column are inclined in the same direction. This arrangement allows the first cell series-connection elements 30 to be installed automatically and can be installed more quickly, improving production efficiency. For example, a robot arm can be used to place the first cell series-connected elements 30 on the cells 12, and the positive and negative terminals 13, 14 of the cells 12 have the above-described aligned characteristics, and the orientation of the first cell series-connected elements 30 located in the same column is the same, so the robot arm can continuously place the first cell series-connected elements 30 in the same column without having to rotate to change direction. The arrangement of the cells 12 shown in Figure 3 can reduce errors that may occur in conventional battery packs due to the need to alternate cell electrodes during manufacturing, and can improve production efficiency.

[0029] Please refer to Figure 4. Figure 4 is an enlarged view of the first cell series-connected element 30 of the battery pack 21 shown in Figure 2. The multi-layer structure 31 of the first cell series-connected element 30 includes a plurality of first metal sheets 60 stacked one on top of the other, with a gap 35 between any two adjacent first metal sheets 60, which can be used for airflow. Two fixing members 32 clamp and fix both ends of the first metal sheets 60 to join the plurality of first metal sheets 60 together. In some embodiments, the fixing member 32 is a sheet metal member folded in half.

[0030] 4, each first metal sheet 60 has an intermediate segment 65 located between two fixing members 32. The intermediate segments 65 of any two adjacent first metal sheets 60 are separated from each other to form a gap 35. The fixing members 32 have openings 33, which may be in the form of, for example, round holes. The provision of the openings 33 facilitates welding or screwing the fixing members 32 to the corresponding electrode terminals 15.

[0031] See Figure 5. Figure 5 is a side view of the first cell series-connected element 30 shown in Figure 4. In some embodiments, the fixing member 32 includes a second metal sheet, which is folded to form a recess 34, an end of the first metal sheet 60 is inserted into the recess 34, and the first metal sheet 60 and the fixing member 32 are fixed together by ultrasonic welding. In some embodiments, the thickness of the second metal sheet is greater than the thickness of each of the first metal sheets 60. In some embodiments, the hardness of the material of the second metal sheet is greater than the hardness of the material of each of the first metal sheets 60. In some embodiments, the first metal sheet 60 and the second metal sheet include copper alloys with different hardnesses.

[0032] As shown in FIG. 5 , each first metal sheet 60 further includes a first planar segment 61 and a second planar segment 62. The first planar segment 61 and the second planar segment 62 are separated from each other, and the intermediate segment 65 is located between the first planar segment 61 and the second planar segment 62. The first planar segment 61 and the second planar segment 62 have different heights. Two fixing members 32 sandwich the first planar segment 61 and the second planar segment 62 of the first metal sheet 60, respectively. One end of each of the first metal sheets 60 is received in the recess 34 of the fixing member 32 after being overlapped with the first planar segment 61, and the other end of each of the first metal sheets 60 is received in the recess 34 of the other fixing member 32 after being overlapped with the second planar segment 62. The intermediate segment 65 is substantially parallel to the first planar segment 61 and the second planar segment 62.

[0033] 5 , each first metal sheet 60 further includes a first beveled segment 63 and a second beveled segment 64. The first beveled segment 63 is connected between the first flat segment 61 and the middle segment 65, and the second beveled segment 64 is connected between the second flat segment 62 and the middle segment 65. The first metal sheets 60 are bent one by one at the first beveled segments 63 so that any two adjacent first metal sheets 60 form a gap 35 at the middle segment 65. Similarly, the first metal sheets 60 are bent one by one at the second beveled segments 64 so that any two adjacent first metal sheets 60 form a gap 35 at the middle segment 65.

[0034] In some embodiments, a manufacturing method of the first cell series-connected element 30 includes folding two oblique surfaces of a plurality of planar metal sheets to form a plurality of first metal sheets 60, overlapping the plurality of first metal sheets 60, clamping first planar segments 61 and second planar segments 62 at both ends of the first metal sheets 60 using two fixing members 32, and ultrasonically welding the two fixing members 32 and the first planar segments 61 and second planar segments 62 at both ends of the first metal sheets 60. After welding, the first cell series-connected element 30 and each of the first metal sheets 60 do not contact each other at the intermediate segments 65, forming gaps 35.

[0035] Please refer to Figure 6. Figure 6 is an enlarged view of the first cell series-connected element 30 and the cell 12 of a portion of the battery pack 21 shown in Figure 2. In some embodiments, the middle segment 65 of the lowest (i.e., closest to the cell 12) first metal sheet 60 is higher than the electrode terminal 15 of the cell 12 and the top surface 17 of the cell 12, thereby forming an air flow path 19 between the lowest first metal sheet 60 and the top surface 17 of the cell 12, which helps to dissipate heat from the cell 12.

[0036] Please refer to FIG. 7. FIG. 7 is a perspective view of a first cell series-connected element 30A according to another embodiment of the present disclosure. The first cell series-connected element 30A of this embodiment includes a plurality of first metal sheets 70. The difference between the first metal sheets 70 and the first metal sheet 60 is that at least one of the plurality of first metal sheets 70 includes at least one folded portion 77, which can provide support for the first metal sheet 70. In some embodiments, the first metal sheet 70 includes adjacent metal sheets M1 and M2. The middle segment 75 of the metal sheet M1 includes a flat region 76, and the middle segment 75 of the metal sheet M2 includes a folded portion 77, which protrudes toward the metal sheet M1 and abuts against the flat region 76 of the metal sheet M1. In some embodiments, the metal sheet M1 is located below the metal sheet M2, and the folded portion 77 of the metal sheet M2 protrudes downward and abuts against the metal sheet M1. In some embodiments, the bottom first metal sheet 70 does not include a fold 77 .

[0037] Please refer to FIG. 8. FIG. 8 is a perspective view of a first cell series-connected element 30B according to another embodiment of the present disclosure. The first cell series-connected element 30B of this embodiment includes a plurality of first metal sheets 80. The difference between the first metal sheets 80 and the first metal sheet 60 is that at least one of the plurality of first metal sheets 80 includes at least one folded edge 87, which can provide support for the first metal sheet 80. In some embodiments, the first metal sheet 80 includes adjacent metal sheets M1 and M2. The middle segment 85 of the metal sheet M2 has a notch 86 and a folded edge 87 extending from the edge of the notch 86, and the folded edge 87 is folded toward the metal sheet M1 and abuts against the middle segment 85 of the metal sheet M1. In some embodiments, the metal sheet M1 is located below the metal sheet M2, and the folded edge 87 of the metal sheet M2 is folded downward and abuts against the metal sheet M1. In some embodiments, the bottom first metal sheet 80 does not include a folded edge 87 .

[0038] See FIG. 9 , which is a schematic side view of a first cell series-connected element 30C according to another embodiment of the present disclosure. The first cell series-connected element 30C of this embodiment includes a plurality of first metal sheets 90. The difference between the first metal sheets 90 and the first metal sheet 60 is that at least two of the plurality of first metal sheets 90 have different lengths. When the ends of the first metal sheets 90 of different lengths are aligned, the middle segment 65 of the long first metal sheet 90 warps, forming a gap 35 between the two first metal sheets 90. In some embodiments, the first metal sheets 90 include adjacent metal sheets M1 and M2, with the metal sheet M1 located below the metal sheet M2. The ends of the metal sheet M1 and the metal sheet M2 are overlapped (e.g., the first planar segment 61 of the metal sheet M1 and the first planar segment 61 of the metal sheet M2 are overlapped, and the second planar segment 62 of the metal sheet M1 and the second planar segment 62 of the metal sheet M2 are overlapped), and the length of the metal sheet M1 is smaller than the length of the metal sheet M2.

[0039] 9, in some embodiments, the outer edges of the first planar segments 61 of the metal sheets M1, M2 may be aligned with one another, and the outer edges of the second planar segments 62 of the metal sheets M1, M2 may also be aligned with one another. The first beveled segments 63 of the metal sheets M1, M2 may be separated from one another as shown or may contact one another. Similarly, the second beveled segments 64 of the metal sheets M1, M2 may be separated from one another as shown or may contact one another. In some embodiments, the lengths of all of the first metal sheets 90 of the first cell series-connected element 30C are different.

[0040] As described above, the present disclosure provides a cell series connection element for connecting multiple cells in series in a battery pack, the cell series connection element having a multi-layer structure including multiple stacked metal sheets with a gap between any two adjacent metal sheets. The multi-layer structure can prevent overheating of the cell series connection element itself, and can also serve as a heat sink coupled to the cells of the cell series connection element to help cool the heated cells.

[0041] Although the present disclosure has been disclosed in the above embodiments, the above embodiments are not used to limit the present disclosure, and anyone skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on what is defined in the appended claims. [Explanation of symbols]

[0042] 12: Cell 13: Positive terminal 14: Negative terminal 15: Electrode terminal 17:Top surface 19: Air flow path 20: Energy storage cabinet 21: Battery pack 22: Bracket 23: Layer assembly 26: Connection device 28: Cooling device 29: Housing 30, 30A, 30B, 30C: first cell series-connected elements 31:Multilayer structure 32: Fixing member 33:Aperture 34: Recess 35: Gap 40: Second cell series-connected element 41: First side opening 42: Second side opening 60, 70, 80, 90: First metal sheet 61: First planar segment 62: Second planar segment 63: First slope segment 64: Second slope segment 65, 75, 85: Middle segment 76: Planar area 77: Bending part 86: Notch 87: Folded edge D: Direction M1, M2: Metal sheets

Claims

1. A cell series connection element, a multi-layer structure including a plurality of first metal sheets arranged in a stack, the multi-layer structure having a gap between any two adjacent ones of the plurality of first metal sheets; two fixing members for clamping and fixing both ends of the multilayer structure and electrically connecting the two fixing members to electrode terminals of a cell; A cell series connection element comprising:

2. 2. The cell series connection element of claim 1, wherein the two fixing members include a second metal sheet, the second metal sheet is folded to form a recess, and ends of the plurality of first metal sheets are inserted into the recess.

3. The cell series-connected element of claim 2 , wherein a thickness of the second metal sheet is greater than a thickness of each of the plurality of first metal sheets.

4. The cell series-connected element of claim 2 , wherein a hardness of the material of the second metal sheet is greater than a hardness of a material of each of the plurality of first metal sheets.

5. 2. The cell series-connection element according to claim 1, wherein each of the plurality of first metal sheets includes a first planar segment, a second planar segment, and an intermediate segment, the first planar segment and the second planar segment being separated from each other, the intermediate segment being located between the first planar segment and the second planar segment, and the first planar segment and the second planar segment having different heights, and the two fixing members respectively sandwich the first planar segment and the second planar segment.

6. 6. The cell series-connected element of claim 5, wherein each of the plurality of first metal sheets further includes a first sloping segment and a second sloping segment, the first sloping segment being connected between the first planar segment and the intermediate segment, and the second sloping segment being connected between the second planar segment and the intermediate segment, and the plurality of first metal sheets are folded one by one at the first sloping segment and the second sloping segment such that the intermediate segments of any two adjacent ones of the plurality of first metal sheets form the gap.

7. 2. The cell series connection element of claim 1, wherein the plurality of first metal sheets include adjacent third and fourth metal sheets, the third metal sheet including an intermediate segment, the fourth metal sheet having a notch and a folded edge extending from an edge of the notch, the folded edge being folded toward the third metal sheet and abutting the intermediate segment of the third metal sheet.

8. 2. The cell series connection element of claim 1, wherein the plurality of first metal sheets include adjacent third and fourth metal sheets, the third metal sheet including a planar region, and the fourth metal sheet including a bent portion, the bent portion protruding toward the third metal sheet and abutting the planar region of the third metal sheet.

9. 2. The cell series connection element of claim 1, wherein the plurality of first metal sheets include adjacent third and fourth metal sheets, the third metal sheet is located below the fourth metal sheet, an end of the third metal sheet and an end of the fourth metal sheet are overlapped, and a length of the third metal sheet is smaller than a length of the fourth metal sheet.

10. A battery pack comprising: Housing and a plurality of cells disposed within the housing, each including a positive terminal and a negative terminal, arranged in at least one row along one direction, such that in the direction, the positive terminals of the cells located in the same row among the plurality of cells are aligned with one another, and the negative terminals of the cells located in the same row among the plurality of cells are aligned with one another; a plurality of cell series-connected elements each including a multi-layer structure and two fixing members, the multi-layer structure including a plurality of first metal sheets arranged in a stacked manner, with a gap between any two adjacent ones of the plurality of first metal sheets, the two fixing members fixing and sandwiching both ends of the multi-layer structure, and each electrically connected to the positive electrode terminal and the negative electrode terminal of two adjacent ones of the plurality of cells; Including the battery pack.

11. 11. The battery pack of claim 10, wherein the housing has a first side opening and a second side opening, the first side opening and the second side opening being provided on opposite sides of the housing and facing the plurality of cell series-connected elements.

12. 11. The battery pack of claim 10, wherein the two fixing members include a second metal sheet, the second metal sheet is folded in half to form a recess, ends of the plurality of first metal sheets are inserted into the recess, and a thickness of the second metal sheet is greater than a thickness of each of the plurality of first metal sheets, or a hardness of the second metal sheet is greater than a hardness of each of the plurality of first metal sheets.

13. 11. The battery pack of claim 10, wherein the plurality of first metal sheets include adjacent third and fourth metal sheets, the third metal sheet including an intermediate segment, the fourth metal sheet having a notch and a folding edge extending from an edge of the notch, the folding edge being folded toward the third metal sheet and abutting the intermediate segment of the third metal sheet.

14. 11. The battery pack of claim 10, wherein the plurality of first metal sheets include adjacent third and fourth metal sheets, the third metal sheet including a planar region, and the fourth metal sheet including a bent portion, the bent portion protruding toward the third metal sheet and abutting the planar region of the third metal sheet.

15. 11. The battery pack of claim 10, wherein the plurality of first metal sheets include a third metal sheet and a fourth metal sheet adjacent to each other, the third metal sheet is located below the fourth metal sheet, an end of the third metal sheet and an end of the fourth metal sheet are overlapped, and a length of the third metal sheet is smaller than a length of the fourth metal sheet.

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