Battery pack manufacturing method and battery pack

Abstract

To provide a manufacturing method of a battery pack capable of manufacturing a high-quality battery pack by suppressing occurrence of a weld defect of a bus bar to terminals of cells, and the battery pack.SOLUTION: The present invention relates to a manufacturing method of a battery pack 10 in which a stack 15 configured by stacking a plurality of cells 11 to which a resin frame 14 is mounted is stored in a box-shaped battery case 12 and a bus bar 13 is welded and bonded to terminals 31 and 32 of the cells 11. The manufacturing method includes: a storage step of storing the stack 15, which is configured by stacking the plurality of cells 11, in the battery case 12; an alignment step of aligning the plurality of cells 11 by pushing them to a reference face 22A consisting of one side face of the battery case 12 in parallel with a stacking direction of the cells 11; and a bonding step of welding and bonding the bus bar 13 to the terminals 31 and 32 of the cells 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a battery pack and a battery pack. [Background technology]

[0002] For example, a battery pack mounted on an electric vehicle, a hybrid vehicle, or the like is configured by housing a stack of a plurality of cells, such as lithium ion secondary batteries, in a box-shaped battery case.

[0003] Patent Document 1 discloses a technology for manufacturing a battery pack in which a stack is pressed in the stacking direction to be constrained and inserted into a battery case, a shim is inserted into the space between the end face of the stack in the stacking direction and the inner wall surface of the battery case, and resin is injected into the bag-shaped member of the shim, thereby constraining the stack by the battery case and the shim. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-87704 Summary of the Invention [Problem to be solved by the invention]

[0005] In a battery pack, after the stack is housed in the battery case, a bus bar module is assembled on top of the stack, and the bus bars provided on this bus bar module are welded and joined to the terminals of each cell by laser welding or the like.

[0006] For this reason, as shown in Figure 10, the resin frame 3 holding each cell 1 is abutted against a positioning reference surface 4 to align the terminals 2 of each cell 1 in a row, forming a stack 5, and as shown in Figure 11, the stack 5 is housed in a battery case 6 while being pressed in the thickness direction of the cells 1.

[0007] However, the width of the battery case 6 that houses the stack 5 is designed to be larger than the width of the cells 1. Therefore, after being housed in the battery case 6, each cell 1 may move in the width direction, causing variations in the positions of the terminals 2 of each cell 1. Also, as shown in Figure 12, the thickness of the cells 1 varies in the width direction within the tolerance range.

[0008] For this reason, when the cells 1 are stacked and housed in a battery case 6, the arrangement of the terminals 2 of each cell 1 may not be linear but may be curved or wavy, as shown in Fig. 13. This makes it difficult to smoothly weld the bus bars 8 of the bus bar module 7 to the terminals 2 of the cells 1, as shown in Fig. 14, which may result in poor welding.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a battery pack manufacturing method and a battery pack that are capable of manufacturing high-quality battery packs by suppressing the occurrence of poor welding of bus bars to cell terminals. [Means for solving the problem]

[0010] In order to achieve the above object, the manufacturing method of the battery pack of the present invention includes the steps of: A method for manufacturing a battery pack in which a stack of cells, each having a resin frame attached thereto, is housed in a box-shaped battery case, and bus bars are welded and joined to terminals of the cells, a housing step of housing the stack, in which a plurality of the cells are stacked, in the battery case; an alignment step of aligning the plurality of cells by pressing them against one side surface of the battery case that is parallel to the stacking direction of the cells; a joining step of welding the bus bar to a terminal of the cell; Includes:

[0011] According to this battery pack manufacturing method, before welding the bus bars to the cell terminals, the cells housed in the battery case are pressed against one side of the battery case parallel to the stacking direction to align them. This reduces variation in the terminal positions of the cells and reduces poor welding of the bus bars to the cell terminals. This allows for the manufacturing of high-quality battery packs.

[0012] In the method for manufacturing a battery pack of the present invention, in the aligning step, the cells may be urged and pressed toward one side surface of the battery case by an urging portion provided on the resin frame.

[0013] According to the manufacturing method of the battery pack having this configuration, the cells are urged and pressed toward one side of the battery case by the urging portion of the resin frame, so that multiple cells can be easily aligned inside the battery case.

[0014] In the method for manufacturing a battery pack of the present invention, in the aligning step, the cells may be pressed against one side surface of the battery case by a jig.

[0015] According to the manufacturing method of the battery pack having this configuration, by pressing the cells against one side of the battery case with a jig, it is possible to easily align the multiple cells inside the battery case.

[0016] The battery pack of the present invention further comprises: A plurality of cells each having a resin frame attached thereto; a box-shaped battery case that houses a stack of the plurality of cells; a bus bar welded to the terminal of the cell; Equipped with A plurality of the cells are aligned and pressed against one side of the battery case that is parallel to the stacking direction of the cells.

[0017] In a battery pack with this configuration, the bus bars are welded and joined to the terminals of the cells that are aligned and pressed against one side of the battery case that is parallel to the stacking direction, resulting in a high-quality battery pack with no defective welding of the bus bars to the cell terminals.

[0018] In the battery pack of the present invention, the resin frame may include a biasing portion that biases the cell toward one side surface of the battery case.

[0019] In a battery pack with this configuration, the cells are biased toward one side of the battery case by the biasing portion of the resin frame, aligning them, resulting in a high-quality battery pack with no poor welding of the bus bars to the cell terminals. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a battery pack manufacturing method and a battery pack that can manufacture a high-quality battery pack by suppressing the occurrence of defective welding of bus bars to cell terminals. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a schematic plan view of the battery pack according to the embodiment. [Figure 2] FIG. 2 is a schematic plan view of a battery case housing a stack of stacked cells. [Figure 3] 3 is a cross-sectional view taken along the line AA in FIG. 2. [Figure 4] FIG. 2 is a schematic plan view of a busbar module including a busbar. [Figure 5] 3 is a cross-sectional view taken along the line AA in FIG. 2, showing a modified example of the biasing portion provided in the resin frame. FIG. [Figure 6] 3 is a cross-sectional view taken along the line AA in FIG. 2, showing a modified example of the biasing portion provided in the resin frame. FIG. [Figure 7] 3 is a cross-sectional view taken along the line AA in FIG. 2, showing a modified example of the biasing portion provided in the resin frame. FIG. [Figure 8]FIG. 10 is a schematic plan view of a battery case containing a stack of stacked cells, illustrating a method for manufacturing a battery pack according to another embodiment. [Figure 9] 9 is a cross-sectional view of FIG. 8 taken along line BB. [Figure 10] FIG. 1 is a schematic perspective view illustrating a conventional example of a cell alignment process. [Figure 11] FIG. 10 is a schematic perspective view illustrating a conventional example of a process for accommodating a stack in a battery case. [Figure 12] FIG. 1 is a schematic diagram of a stack illustrating the disorder in alignment when cells are stacked. [Figure 13] FIG. 2 is a schematic plan view of a battery case housing a stack of stacked cells. [Figure 14] FIG. 2 is a schematic plan view of a battery case with a bus bar module assembled thereto. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 is a schematic plan view of a battery pack according to this embodiment. Fig. 2 is a schematic plan view of a battery case that houses a stack of stacked cells. Fig. 3 is a cross-sectional view taken along line AA in Fig. 2. Fig. 4 is a schematic plan view of a busbar module equipped with a busbar.

[0023] 1, a battery pack 10 according to this embodiment includes a plurality of cells 11, a battery case 12, and a bus bar 13. The battery pack 10 is mounted on, for example, an electric vehicle or a hybrid vehicle.

[0024] As shown in Figures 2 and 3, a resin frame 14 is attached to the cell 11, and multiple cells 11 with the resin frames 14 attached are stacked to form a stack 15 and housed in the battery case 12.

[0025] The battery case 12, which houses the stack 15 made up of multiple cells 11, is formed in a box shape having a bottom plate 21, a pair of side plates 22, and a pair of end plates 23. The inner surface of one of the side plates 22 of the battery case 12 is set as a reference surface 22A.

[0026] The cell 11 is, for example, a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. The cell 11 is formed in a flat rectangular parallelepiped shape, and a positive electrode terminal 31 is provided near one end of the upper portion thereof, and a negative electrode terminal 32 is provided near the other end thereof.

[0027] The resin frame 14 attached to the cell 11 is molded from an insulating resin material and includes a plate-shaped portion 41, side plate portions 42 provided on both side edges of the plate-shaped portion 41, a bottom plate portion 43 provided on the lower edge of the plate-shaped portion 41, and locking pieces 44 provided on both end portions of the upper edge of the plate-shaped portion 41. The resin frame 14 is attached to the cell 11 from one side of the cell 11. With the resin frame 14 attached, one side of the cell 11 is covered by the plate-shaped portion 41, both side surfaces are covered by the side plate portions 42, and the bottom surface is covered by the bottom plate portion 43. Furthermore, the upper portions of the cell 11 at both ends are locked by the locking pieces 44 of the resin frame 14. The resin frame 14 also has a biasing portion 45 on one side plate portion 42. The biasing portion 45 is molded integrally with the resin frame 14, and is formed in a plate shape with both ends connected to one side plate portion 42 of the resin frame 14 and bulging outward.

[0028] When the cells 11 are stacked and housed in the battery case 12 as a stack 15, the biasing portion 45 of the resin frame 14 abuts against one inner surface 22B of the battery case 12, which is opposite to one inner surface serving as the reference surface 22A, and elastically deforms. As a result, the restoring force of the elastically deformed biasing portion 45 is applied to each cell 11 as a biasing force, and the cell 11 is pressed against the reference surface 22A of the battery case 12. As a result, the cells 12 housed in the battery case 12 are aligned along the reference surface 22A of the battery case 12. As a result, the terminals 31, 32 of each cell 11 are linearly arranged in the stacking direction of the cells 11 (see the dashed dotted line in FIG. 2 ).

[0029] As shown in FIG. 4 , the busbar 13 has a U-shape in plan view and includes a pair of connection pieces 51 and a connecting piece 52 connecting the ends of the connection pieces 51. The busbar 13 is formed from a conductive metal plate such as copper or a copper alloy. The busbar 13 is supported by connecting pieces 52 connected to a support plate 54 made of a flexible printed wiring board via connecting members 53. These busbars 13 are supported by the support plate 54 to form a busbar module 55. A plurality of busbars 13 are arranged on both sides of the support plate 54 with their connection pieces 51 facing outward. The connection pieces 51 have connection portions 51 a that are connected to the terminals 31 and 32 of the cells 11, respectively. The connection portions 51 a of the connection pieces 51 of the busbars 13 arranged on both sides of the support plate 54 are arranged in a straight line (see the dashed dotted line in FIG. 4 ).

[0030] A voltage detection line 56 and a temperature detection line 57 each made of a conductor pattern are provided on a support plate 54 made of a flexible printed wiring board. The voltage detection line 56 is connected to each bus bar 13, and the temperature detection line 57 is connected to a thermistor provided on a specific bus bar 13.

[0031] As shown in FIG. 1 , a busbar module 55, in which busbars 13 are supported on a support plate 54, is disposed on top of a stack 15 made up of a plurality of cells 11 housed in a battery case 12. The busbars 13 of the busbar module 55 are connected by welding the connection portions 51 a of their connection pieces 51 to the terminals 31, 32 of each cell 11. This connects the cells 11, each having the busbar 13 connected to the terminals 31, 32, in series. Furthermore, a voltage detection wire 56 and a temperature detection wire 57 of the support plate 54 are connected to a battery monitor (not shown). This allows the battery monitor to detect the voltage and temperature of the cell 11.

[0032] Next, a method for manufacturing the battery pack 10 having the above configuration will be described. As shown in Figures 2 and 3, to manufacture the battery pack 10, first, multiple cells 11 held in a resin frame 14 are stacked to form a stack 15, and this stack 15 is then housed inside the battery case 12 (housing process).

[0033] When the stack 15 is housed inside the battery case 12, the cells 11 are elastically deformed as the biasing portions 45 provided on the resin frame 14 come into contact with the inner surface 22B of the battery case 12. As a result, each cell 11 is pressed against the reference surface 22A, which is one side surface of the battery case 12 that is parallel to the stacking direction of the cells 11, by the biasing force formed by the restoring force of the elastically deformed biasing portions 45, and aligned (alignment step). As a result, the terminals 31, 32 of each cell 11 are aligned linearly along the stacking direction of the cells 11 (see the dashed line in FIG. 2).

[0034] Next, the busbar module 55, in which the busbars 13 are supported on the support plates 54, is placed on top of the stack 15 made up of a plurality of cells 11 housed in the battery case 12, and the connection portions 51a of the connection pieces 51 of each busbar 13 are positioned on the terminals 31, 32 of each cell 11. In this state, a laser is irradiated onto the connection portions 51a of the connection pieces 51 of the busbar 13, and the connection portions 51a are laser-welded to the terminals 31, 32 to join them (joining process).

[0035] As a result, a battery pack 10 is obtained in which a plurality of cells 11 are stacked and housed in the battery case 12, and the bus bars 13 are welded and joined to each cell 11.

[0036] As described above, according to the manufacturing method of the battery pack 10 of this embodiment, before welding the bus bar 13 to the terminals 31, 32 of the cells 11, the cells 11 housed in the battery case 12 are pressed against the reference surface 22A, which is one side surface of the battery case 12 that is parallel to the stacking direction, to align them. This reduces variation in the terminal positions of the cells 11 and suppresses the occurrence of defective welding of the bus bar 13 to the terminals 31, 32 of the cells 11. Therefore, the battery pack 10 manufactured by this manufacturing method can be a high-quality battery pack without defective welding of the bus bar 13 to the terminals 31, 32 of the cells 11.

[0037] In addition, by providing a biasing portion 45 on the resin frame 14 and biasing and pressing the cells 11 toward the reference surface 22A of the battery case 12 by the biasing portion 45 of the resin frame 14, multiple cells 11 can be easily aligned within the battery case 12.

[0038] The biasing portion 45 of the resin frame 14 attached to the cell 11 is not limited to the one exemplified in the above embodiment, as long as it biases the cell 11 toward the reference surface 22A. 5 to 7 are cross-sectional views taken along the line AA in FIG. 2, each showing a modified example of the biasing portion provided on the resin frame.

[0039] The urging portion 45A shown in FIG. 5 is formed in a plate shape with one end connected to one side plate portion 42 of the resin frame 14. The urging portion 45B shown in FIG. 6 is formed in a U-shape with both ends connected to one side plate portion 42 of the resin frame 14 and protruding outward. A plurality of these urging portions 45B are provided in the height direction of the cell 11. The urging portion 45C shown in FIG. 7 is formed in a U-shape with one end connected to one side plate portion 42 of the resin frame 14 and the other end protruding outward. A plurality of these urging portions 45C are provided in the height direction of the cell 11.

[0040] When the stack 15, in which the cells 11 are stacked, is housed inside the battery case 12, these biasing portions 45A, 45B, and 45C also come into contact with the inner surface 22B of the battery case 12 and elastically deform. As a result, each cell 11 is pressed against the reference surface 22A, which is one side surface of the battery case 12 that is parallel to the stacking direction of the cells 11, by the biasing force formed by the restoring force of the elastically deformed biasing portions 45A, 45B, and 45C, and is aligned.

[0041] Next, a method for manufacturing the battery pack 10 according to another embodiment will be described. The same components as those in the above embodiment are denoted by the same reference numerals and the description thereof will be omitted. Fig. 8 is a schematic plan view of a battery case accommodating a stack of stacked cells, illustrating a method for manufacturing a battery pack according to another embodiment. Fig. 9 is a cross-sectional view taken along line BB in Fig. 8.

[0042] As shown in FIGS. 8 and 9, in another embodiment, the cells 11 housed inside the battery case 12 are aligned using a jig 60.

[0043] The jig 60 is formed in a rod shape and has a pressing surface 61 and a tapered surface 62. The tapered surface 62 is inclined in a direction gradually separating from the pressing surface 61 toward the rear end, thereby giving the jig 60 a tapered shape that narrows toward the front end.

[0044] To align the cells 11 using the jig 60, the jig 60 is inserted from above between the cells 11 housed inside the battery case 12 and the inner surface 22B of the battery case 12. At this time, the pressing surface 61 of the jig 60 is positioned on the cell 11 side. Furthermore, a roller 63 is placed against the tapered surface 62 of the jig 60, and the jig 60 is pressed between the cells 11 and the inner surface 22B of the battery case 12. Then, the jig 60 is guided by the rotating roller 63 and inserted between the cells 11 and the inner surface 22B of the battery case 12, and the pressing surface 61 of the jig 60 presses the cells 11 against the reference surface 22A of the battery case 12. This aligns the cells 11 housed inside the battery case 12. In this state, the cells 11 aligned inside the battery case 12 are pressed in the stacking direction by a pressure means (not shown), maintaining the aligned state of the cells 11, and the jig 60 is removed.

[0045] Thereafter, the busbar module 55 is placed on top of the stack 15 made up of a plurality of cells 11 housed in the battery case 12, and the connection portions 51a of the connection pieces 51 of each busbar 13 are positioned on the terminals 31, 32 of each cell 11. Then, a laser is irradiated onto the connection portions 51a of the connection pieces 51 of the busbar 13, and the connection portions 51a are joined to the terminals 31, 32 by laser welding.

[0046] According to another embodiment of the manufacturing method of the battery pack 10, the cells 11 can be pressed toward the reference surface 22A of the battery case 12 using a jig 60, thereby easily aligning multiple cells 11 within the battery case 12. [Explanation of symbols]

[0047] 10 Battery pack 11 cells 12 Battery case 13 Busbar 14 Resin frame 15 stacks 22A Reference plane (one side) Terminals 31 and 32 45,45A,45B,45C Force section 60 Jig

Claims

1. A method for manufacturing a battery pack in which a stack of cells, each having a resin frame attached thereto, is housed in a box-shaped battery case, and bus bars are welded and joined to terminals of the cells, a housing step of housing the stack, in which a plurality of the cells are stacked, in the battery case; an alignment step of aligning the plurality of cells by pressing them against one side surface of the battery case that is parallel to the stacking direction of the cells; a joining step of welding the bus bar to a terminal of the cell; Including, Battery pack manufacturing method.

2. In the aligning step, the cells are urged and pressed toward one side surface of the battery case by an urging portion provided on the resin frame. The method for manufacturing the battery pack according to claim 1 .

3. In the alignment step, the cells are pressed against one side surface of the battery case using a jig. The method for manufacturing the battery pack according to claim 1 .

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