Battery module

Abstract

To obtain a battery module capable of improving an accommodation efficiency of a plurality of battery cells to a module case.SOLUTION: A battery module 11 comprises a plurality of battery cells 20 in which a plate-like electrode body 40 constructing a positive electrode and a negative electrode is coated with a laminate film 22, and an electrode lead 26 is projected from one end and the other sides in a width direction W. The plurality of battery cells 20 are laminated in a thickness direction D, and is housed in a module case 16. At least some of the plurality of battery cells 20 are continuously connected via a connection part 70 connecting both of the electrode leads 26, and laminated so as to be folded in a cornice shape at a position of the connection part 70 and thereby electrically connected.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a battery module.

Background Art

[0002] Patent Document 1 below describes a cell module in which a plurality of double-tab type cells each having a sheet-like positive electrode terminal and a negative electrode terminal extending in opposite directions from the outer peripheral edge of the cell body are arranged in parallel, and a pair of substantially plate-like bus bars are arranged in the terminal extension direction to connect the same-pole terminals among the respective terminals. A plurality of cell modules are stacked and arranged such that bus bars having different polarities face each other.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the cell module described in Patent Document 1, the connection between the double-tab type cells facing each other in the stacking direction is performed via a pair of bus bars and a conductive columnar member that connects the pair of bus bars. For this reason, a space for accommodating the pair of bus bars and the conductive columnar member is required between the double-tab type cells facing each other in the stacking direction, and the accommodation efficiency of the double-tab type cells in the module case decreases.

[0005] In consideration of the above facts, an object of the present invention is to obtain a battery module capable of improving the accommodation efficiency of a plurality of battery cells in a module case.

Means for Solving the Problems

[0006] The battery module according to the first aspect includes a plurality of battery cells in which plate-shaped electrode bodies constituting a positive electrode and a negative electrode are externally covered with a laminate film and electrode leads protrude from one side and the other side in the width direction, and the plurality of battery cells are stacked in the thickness direction and housed in a module case. At least a part of the plurality of battery cells are electrically connected by being continuously connected via a connection portion that connects the electrode leads to each other and being folded in a bellows shape and stacked at the position of the connection portion.

[0007] The battery module according to the first aspect includes a plurality of battery cells in which plate-shaped electrode bodies constituting a positive electrode and a negative electrode are externally covered with a laminate film and electrode leads protrude from one side and the other side in the width direction. Further, in the battery module, the plurality of battery cells are stacked in the thickness direction and housed in a module case. Here, at least a part of the plurality of battery cells are electrically connected by being continuously connected via a connection portion that connects the electrode leads to each other and being folded in a bellows shape and stacked at the position of the connection portion. In this way, by directly connecting the electrode leads to each other, the number of bus bars for electrically connecting between the battery cells can be reduced, and miniaturization can be achieved. As a result, the housing efficiency of the plurality of battery cells in the module case can be improved.

Advantages of the Invention

[0008] As described above, in the battery module according to the present invention, the housing efficiency of the plurality of battery cells in the module case can be improved.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0010] Hereinafter, with reference to FIGS. 1 to 3, an embodiment of the present invention will be described. In each of FIGS. 1 to 3, the direction indicated by arrow W is the width direction of the battery cell 20, the direction indicated by arrow H is the height direction (vertical direction) of the battery cell 20, and the direction indicated by arrow D is the thickness direction of the battery cell 20. The width direction W of the battery cell 20 coincides with the width direction of the electrode sheet 50 and the separator 60 described later.

[0011] (Battery Cell) FIG. 1 is a schematic view of a single battery cell seen from the thickness direction D. As shown in FIG. 1, the battery cell 20 is formed in a flat and long rectangular plate shape with the width direction W as the longitudinal direction, and constitutes a secondary battery capable of charging and discharging.

[0012] The battery cell 20 has a rectangular plate-shaped electrode body 40 (see FIG. 2) and a laminate film 22 that externally packages (seals) the electrode body 40. The electrode body 40 is connected to electrode leads 26 that protrude in the width direction W at one end and the other end in the width direction W. The electrode leads 26 have a first electrode lead 26A that is connected to the positive electrode of the electrode body 40 on one side in the width direction W and a second electrode lead 26B that is connected to the negative electrode of the electrode body 40 on the other side in the width direction W. The first electrode lead 26A and the second electrode lead 26B are formed in a rectangular plate shape with the width direction W as the longitudinal direction. The laminate film 22 is embossed on at least one side in the thickness direction. By performing the embossing process, a concave accommodating portion 221 (see FIG. 2) in which the electrode body 40 is accommodated is formed on the side surface.

[0013] FIG. 2 is a schematic diagram for explaining the internal structure of the battery cell 20, and shows a state as viewed from the height direction H with the battery cell 20 disassembled. As shown in FIG. 2, the laminate film 22 has a first laminate film 22A disposed on one side in the thickness direction D of the electrode body 40 and a second laminate film 22B disposed on the other side in the thickness direction D of the electrode body 40. The first laminate film 22A and the second laminate film 22B are overlapped in the thickness direction D on both sides of the electrode body 40, and the outer peripheral portions are heat-sealed to form an accommodation space for the electrode body 40. In the present embodiment, embossing is performed on one side of the second laminate film 22B to form an accommodation portion 221. The laminate film 22 can adopt both a single cup embossing structure with one embossing and a double cup embossing structure with two embossings. In the present embodiment, a single cup embossing structure in which an accommodation portion 221 having a drawing depth of about 8 mm to 10 mm is formed on one side of the second laminate film 22B is adopted.

[0014] On one side in the width direction W of the battery cell 20, one end of the first electrode lead 26A protrudes in the width direction W from the end of the laminate film 22. On the other side in the width direction W of the battery cell 20, one end of the second electrode lead 26B protrudes in the width direction W from the end of the laminate film 22.

[0015] The length CW1 of the battery cell 20 in the vehicle width direction is, for example, 530 mm to 600 mm, 600 mm to 700 mm, 700 mm to 800 mm, 800 to 900 mm, 1000 mm or more, and the length CW2 of the region in which the electrode body is accommodated is, for example, 500 mm to 520 mm, 600 mm to 700 mm, 700 mm to 800 mm, 800 to 900 mm, 1000 mm or more. The height CH of the battery cell 20 is, for example, 80 mm to 110 mm, 110 mm to 140 mm. Further, the thickness of the battery cell 20 is 5.0 mm to 7.0 mm, 7.0 mm to 9.0 mm, 9.0 mm to 11.0 mm, and the height TH of the electrode lead (terminal) 26 is 40 mm to 50 mm, 50 mm to 60 mm, 60 mm to 70 mm.

[0016] (Electrode body) The electrode body 40 is configured by alternately laminating a plurality of electrode sheets 50 and separators 60. The plurality of electrode sheets 50 include a plurality of positive electrode sheets 52 and a plurality of negative electrode sheets 54. In the electrode body 40, the positive electrode sheets 52 and the negative electrode sheets 54 are alternately laminated via the separators 60.

[0017] The positive electrode sheet 52 is, for example, a sheet-like positive electrode current collector formed of aluminum foil with a positive electrode active material coated on both sides. The positive electrode active material is a material capable of occluding and releasing ions. In the case of a lithium-ion secondary battery, for example, it can be composed of a lithium nickel-based oxide, a lithium cobalt-based oxide (e.g., LiCoO2, etc.), and a lithium manganese-based oxide (e.g., LiMn2O4).

[0018] One end of the positive electrode sheet 52 in the width direction W is a protruding end portion 52A that protrudes from one end of the separator in the width direction. This protruding end portion 52A has no positive electrode active material coated thereon and the positive electrode current collector is exposed. The protruding end portions 52A of the positive electrode sheets 52 are integrated at a predetermined position in the stacking direction (thickness direction D in FIG. 2) of the electrode body 40 together with the protruding end portions 52A of the other positive electrode sheets 52, forming a current collecting portion on the positive electrode side. In the present embodiment, the protruding end portions 52A of the plurality of positive electrode sheets 52 are integrated on the side of the first laminate film 22A, forming a current collecting portion on the positive electrode side, and a first electrode lead 26A is disposed between the current collecting portion and the first laminate film 22A. Thereby, the first electrode lead 26A is connected to the positive electrode of the electrode body 40.

[0019] The negative electrode sheet 54 is, for example, a sheet-like negative electrode current collector formed of copper foil with a negative electrode active material coated on both sides. The negative electrode active material is a material capable of occluding and releasing ions. In the case of a lithium-ion secondary battery, for example, it can be composed of a carbon material, a fluororesin (e.g., polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, etc.), polyvinyl acetate, etc.

[0020] The separator 60 is an insulating layer that maintains the distance between the positive electrode sheet 52 and the negative electrode sheet 54 to prevent the occurrence of a short circuit due to contact, and holds the non-aqueous electrolyte. The separator 60 is composed of, for example, a porous resin flat plate. In the present embodiment, the battery cell 20 has a plurality of separators 60 cut out in a sheet shape, and one separator 60 is disposed between the positive electrode sheet 52 and the negative electrode sheet 54.

[0021] The other end portion in the width direction W of the negative electrode sheet 54 is a protruding end portion 54A that protrudes from the other end portion in the width direction of the separator. This protruding end portion 54A has no negative electrode active material applied thereon and the negative electrode current collector is exposed. The protruding end portions 54A of the protruding end portions 54A of the other negative electrode sheets 54 are integrated on the first laminate film 22A side to form a current collecting portion on the negative electrode side. In the present embodiment, the protruding end portions 54A of the plurality of negative electrode sheets 54 are integrated on the first laminate film 22A side to form a current collecting portion on the negative electrode side, and a second electrode lead 26B is disposed between the current collecting portion and the first laminate film 22A. Thereby, the second electrode lead 26B is connected to the negative electrode of the electrode body 40.

[0022] (Battery module) FIG. 3 is a plan view schematically showing a battery module 11 composed of a plurality of battery cells 20. In FIG. 3, the connection portions between two series-connected cell groups 20DC composed of a plurality of battery cells 20 are shown.

[0023] As shown in FIG. 3, the battery module 11 is configured by stacking and housing a plurality of battery cells 20 in the thickness direction D in a module case 16 that forms a box-shaped accommodation space. At least a part of the plurality of battery cells 20 has two series-connected cell groups 20DC that are electrically connected in parallel.

[0024] The series-connected cell group 20DC is composed of a plurality of battery cells 20 connected in series through a connection portion 70 that connects electrode leads 26 to each other. The series-connected cell group 20DC has a plurality of battery cells 20 connected in series folded in a bellows shape at the position of the connection portion 70 and stacked. Therefore, in the series-connected cell group 20DC, the connection portions 70 between the electrode leads 26 are alternately provided on one side and the other side in the width direction W. The number of battery cells 20 constituting the series-connected cell group 20DC is not particularly limited, and two or more are sufficient. In an example of this embodiment, the series-connected cell group 20DC is composed of three battery cells 20 connected in series.

[0025] Each connection portion 70 connects electrode leads with different electrical polarities to each other. That is, it connects the first electrode lead 26A and the second electrode lead 26B. Therefore, the plurality of battery cells 20 constituting the series-connected cell group 20DC are electrically connected in series through the connection portion 70. The connection portion 70 is, for example, a welded portion such as spot welding.

[0026] Two series-connected cell groups 20DC are electrically connected in parallel through a bus bar 30. Inside the module case 16, a pair of electrode leads 26 with the same electrical polarity face each other in the stacking direction (thickness direction D). The pair of electrode leads 26 protrude from the two series-connected cell groups 20DC respectively and are drawn out toward the bus bar 30 arranged on the side of the battery cell 20.

[0027] The bus bar 30 is formed, for example, in a plate shape with the width direction W of the battery cell 20 as the plate thickness direction, and extends along the stacking direction (thickness direction D) of the battery cell 20. In the module case 16, the bus bar 30 is disposed on one side in the width direction W of the battery cell 20. The pair of electrode leads 26 are inserted into slot-shaped through holes 32 that penetrate the bus bar 30 in the plate thickness direction, and the end portions protruding from the through holes 32 are folded back toward the bus bar 30 side and welded to the surface of the bus bar 30. In the present embodiment, the pair of first electrode leads 26A are overlapped on the surface of the bus bar 30 and joined by simultaneous welding. Thereby, two series-connected cell groups are electrically connected in parallel via the bus bar 30.

[0028] (Function and Effect) As described above, the battery module 11 according to the present embodiment includes a plurality of battery cells 20 in which a plate-shaped electrode body 40 constituting a positive electrode and a negative electrode is externally packaged with a laminate film 22, and the electrode leads 26 protrude from one side and the other side in the width direction W. Further, in the battery module 11, a plurality of battery cells 20 are stacked in the thickness direction and housed in the module case 16. Here, at least a part of the plurality of battery cells 20 are continuously connected via a connection portion 70 that connects the electrode leads 26 to each other, and are folded in a bellows shape and stacked at the position of the connection portion 70, thereby being electrically connected. In this way, by directly connecting the electrode leads 26 to each other, the number of bus bars 30 for electrically connecting between the battery cells 20 can be reduced, and miniaturization can be achieved. Thereby, the accommodation efficiency of the plurality of battery cells 20 in the module case 16 can be improved.

[0029] In addition, in the present embodiment, at least a part of the plurality of battery cells 20 housed in the module case 16 constitutes two series-connected cell groups 20DC in which the plurality of battery cells 20 are electrically connected in series via the connection part 70. Then, these two series-connected cell groups 20DC are electrically connected in parallel via the bus bar 30. In this way, by directly connecting the electrode leads 26 to each other between the battery cells 20 that are electrically connected in series, folding them in a bellows shape, and laminating them, it becomes easy to confirm the battery cell group that is electrically directly connected, and confusion with the parallel connection part via the bus bar 30 does not occur. Therefore, by reducing the bus bar 30, the accommodation efficiency of the battery cells 20 can be improved, and the assembly workability of the module can also be improved.

[0030] As described above, an embodiment of the present invention has been described, but the present invention is not limited to this. For example, in the above embodiment, the electrode leads 26 connected via the bus bar 30 may be connected by directly connecting the electrode leads 26 to each other in the same manner as the connection part 70. That is, the bus bar 30 may be omitted from the configuration of the above embodiment. Further, in the above embodiment, the electrode leads having different electrical polarities are electrically connected via the connection part 70, but the present invention is not limited to this. The electrode leads having the same electrical polarity may be electrically connected via the connection part 70. That is, when a plurality of battery cells are continuously connected via the connection part 70 to form a connected cell group, the connection part 70 may directly connect adjacent battery cells 20 to each other, or may connect them in parallel. These can be appropriately changed according to the design of the battery module.

Explanation of Reference Numerals

[0031] 11 Battery module 16 Module case 20 Battery cell 20DC Series-connected cell group 22 Laminate film 26 Electrode lead 30 Bus bar 40 Electrode body 70 Connection part W-width direction

Claims

【Claim 1】 A battery module comprising a plurality of battery cells in which plate-shaped electrode bodies constituting a positive electrode and a negative electrode are externally packaged with a laminate film, and electrode leads are projected from one side and the other side in the width direction, and the plurality of battery cells are stacked in the thickness direction and housed in a module case, At least a part of the plurality of battery cells Are electrically connected by being continuously connected via a connection portion that connects the electrode leads to each other, and being folded in a bellows shape and stacked at the position of the connection portion, Battery module.

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