Battery module and its manufacturing method

Abstract

This specification provides a technique for simultaneously cooling multiple electrode sheets. [Solution] The battery module comprises a plurality of electrode sheets, a plurality of separators stacked alternately with the plurality of electrode sheets, and an electrolyte sealed between the plurality of electrode sheets, wherein through holes are formed that penetrate the plurality of electrode sheets and the plurality of separators, and the through holes are in communication with the outside and isolated from the space in which the electrolyte is sealed.

Description

Technical Field

[0001] This specification relates to a battery module in which a plurality of electrode sheets are laminated.

Background Art

[0002] Patent Document 1 discloses a battery module in which a plurality of electrode sheets are laminated. A heat dissipation member is disposed between two battery modules.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technology of Patent Document 1, the heat of the battery module is transferred from the surface in contact with the heat dissipation member to the heat dissipation member. While the heat dissipation of the electrode sheet in contact with the heat dissipation member is promoted, the heat dissipation of the electrode sheet not in contact with the heat dissipation member is delayed. The progress of heat dissipation varies between each electrode sheet. This specification provides a technology for simultaneously cooling a plurality of electrode sheets.

Means for Solving the Problems

[0005] The battery module disclosed in this specification includes a plurality of electrode sheets, a plurality of separators alternately laminated with the plurality of electrode sheets, and an electrolyte sealed between the plurality of electrode sheets. Through holes are formed penetrating the plurality of electrode sheets and the plurality of separators. The through holes communicate with the outside and are isolated from the space where the electrolyte is sealed.

[0006] According to the above configuration, by passing a refrigerant through the through holes, each of the plurality of laminated electrode sheets can be cooled simultaneously.

[0007] Details of the technology disclosed herein and further improvements are described in the following "Modes for Carrying Out the Invention". [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of a battery module. [Figure 2] Figure 1 is an enlarged plan view of area II. [Figure 3] This is a cross-sectional view along the line III-III shown in Figure 2. [Figure 4] This diagram shows one step in the manufacturing process of a battery module. [Figure 5] This diagram shows another step in the manufacturing process of a battery module. [Modes for carrying out the invention]

[0009] (Configuration of battery module 2; Figures 1-3) The battery module 2 comprises a plurality of stacked electrode sheets 10 and an outer frame 30 that covers the periphery of the plurality of electrode sheets 10. An electrolyte 50 is injected between the plurality of electrode sheets 10, and the outer frame 30 seals the electrolyte 50 between the plurality of electrode sheets 10. Although this is just one example, the battery module 2 is a module for a lithium-ion battery. An XYZ coordinate system is defined in the figure. The Z axis corresponds to the stacking direction in which the plurality of electrode sheets 10 are stacked.

[0010] Multiple electrode sheets 10 have multiple through holes 101 to 105 that penetrate the multiple electrode sheets 10 along the stacking direction. The multiple through holes 101 to 105 are located in the central region R1 of the battery module 2 when viewed along the stacking direction. The central region R1 is the set of points P1 on an arbitrary straight line L1 that extends radially from the center C1 of the battery module 2 toward the outer edge E1 of the electrode sheets 10, where the distance D1 to the center C1 is shorter than the distance D2 to the outer edge E1. Through hole 101 is located at the center C1 within the central region R1. Through holes 102 and 104 are located on the straight line L1 that extends along the Y-axis within the central region R1. Through holes 103 and 105 are located on the straight line L1 that extends along the X-axis within the central region R1. Note that the positions of through holes 100 to 105 in Figure 1 are just examples. Furthermore, the number of through holes is not limited to five; it may be four or fewer, or six or more.

[0011] Figure 2 is an enlarged plan view of the area around the through-hole 101. Figure 3 is a cross-sectional view of the area around the through-hole 101. As shown in Figure 3, the battery module 2 comprises a plurality of electrode sheets 10 and a plurality of separators 20 stacked alternately with the plurality of electrode sheets 10. The plurality of electrode sheets 10 and the plurality of separators 20 constitute a plurality of secondary battery cells connected in series.

[0012] Figure 3 shows a cross-section of a bipolar electrode sheet 10 among several electrode sheets 10. The bipolar electrode sheet 10 is constructed by laminating a negative electrode film 12 containing a negative electrode active material, a current collector foil 14, and a positive electrode film 16 containing a positive electrode active material. The negative electrode film 12 is provided on one side of the current collector foil 14, and the positive electrode film 16 is provided on the other side of the current collector foil 14. The current collector foil 14 may be, for example, a laminate of aluminum foil and copper foil. Various positive electrode active materials and negative electrode active materials for lithium-ion batteries can be appropriately used for the positive electrode active material and negative electrode active material.

[0013] Although not shown in Figure 3, the multiple electrode sheets 10 comprise a unipolar positive electrode sheet 10 and a unipolar negative electrode sheet 10. The unipolar positive electrode sheet 10 is composed of a positive electrode film 16 and a current collector foil 14 such as copper foil, and the unipolar negative electrode sheet 10 is composed of a negative electrode film 12 and a current collector foil 14 such as aluminum foil. The unipolar positive electrode sheet 10 is laminated at one end in the stacking direction of the multiple bipolar electrode sheets 10, and the unipolar negative electrode sheet 10 is laminated at the other end in the stacking direction of the multiple bipolar electrode sheets 10.

[0014] As shown in Figure 3, the through-hole 101 penetrates multiple electrode sheets 10 and multiple separators 20. The through-hole 101 passes through an opening 12A formed in the negative electrode film 12, an opening 14A formed in the current collector foil 14, an opening 16A formed in the positive electrode film 16, and an opening 20A formed in the separator 20. The openings 14A formed in the current collector foil 14 are connected to each other by an adhesive layer 24 that extends along the lamination direction. The adhesive layer 24 is made of, for example, a thermosetting resin. The adhesive layer 24 isolates the through-hole 101 from the space S1 between two adjacent electrode sheets 10, where the electrolyte 50 is sealed.

[0015] As shown in Figure 2, the openings 12A, 14A, 16A, and 20A are circular. The diameter A1 of the opening 12A of the negative electrode film 12 and the diameter A2 of the opening 16A of the positive electrode film 16 are larger than the diameter A3 of the opening 14A of the current collector foil 14. Also, the diameter A1 of the opening 12A of the negative electrode film 12 is smaller than the diameter A2 of the opening 16A of the positive electrode film 16. Furthermore, the diameter A4 of the opening 20A of the separator 20 is smaller than diameters A1 and A2, and larger than diameter A3. Note that the shapes of the openings 12A, 14A, 16A, and 20A may be other shapes, such as ellipses, oblongs, or polygons. In any case, it is preferable that the opening 12A of the negative electrode film 12 and the opening 16A of the positive electrode film 16 are larger than the opening 14A of the current collector foil 14. Furthermore, the aperture 12A of the negative electrode film 12 is preferably smaller than the aperture 16A of the positive electrode film 16.

[0016] Electrolysis can occur on the negative electrode membrane 12. By making the diameter A1 of the opening 12A of the negative electrode membrane 12 smaller than the diameter A2 of the opening 16A of the positive electrode membrane 16, the amount of electrolysis generated can be reduced.

[0017] The configurations of the other through-holes 102 to 105 are the same as that of the through-hole 101. All of the through-holes 101 to 105 communicate with the outside of the battery module 2. For example, outside air passes through each of the through-holes 101 to 105. The electrodes sheets 10 can be cooled by the air. A fan for sending air into each of the through-holes 101 to 105 may be installed outside. Also, a refrigerant other than air, for example, water, may pass through each of the through-holes 101 to 105, and a pump for supplying the refrigerant into each of the through-holes 101 to 105 may be installed outside.

[0018] Also, each of the through-holes 101 to 105 penetrates through a plurality of electrode sheets 10. By passing a refrigerant through each of the through-holes 101 to 105, a plurality of electrode sheets 10 can be cooled simultaneously.

[0019] Also, as the electrode sheet 10 increases in size, heat dissipation in the central region R1 is slower than that in the periphery of the central region R1. Here, "large size" means, for example, a size of 1 meter or more × 1 meter or more. When heat dissipation in the central region R1 is slow, the temperature of the central region R1 becomes higher than that in the periphery of the central region R1. According to the configuration of this embodiment, each of the through-holes 101 to 105 is located within the central region R1. By promoting heat dissipation in the central region R1 by each of the through-holes 101 to 105, it is possible to reduce the expansion of the temperature difference between the central region R1 and the periphery of the central region R1.

[0020] The battery module 2 is mounted on a vehicle such as an electric vehicle or a hybrid vehicle, for example. Two or more battery modules 2 may be mounted on the vehicle. In this case, two or more battery modules 2 may be stacked. Thereby, between two adjacent battery modules 2, their through-holes 101 to 105 can be coaxially arranged and communicated with each other. In addition, in one modification, between two adjacent battery modules 2, their through-holes 101 to 105 do not necessarily need to be coaxially arranged. Further, in another modification, two or more battery modules 2 may be stacked via a cooling plate (not shown). In this case, the through-holes 101 to 105 of each battery module 2 may be communicated with a refrigerant flow path provided in the cooling plate.

[0021] (Method for manufacturing battery module 2; FIGS. 4 and 5) Referring to FIGS. 4 and 5, the method for manufacturing the battery module 2 will be described. In the first step, a negative electrode self-supporting film 42 containing a negative electrode active material and a positive electrode self-supporting film 46 containing a positive electrode active material are prepared. The negative electrode self-supporting film 42 is a member that becomes the basis of a plurality of negative electrode films 12. By cutting the negative electrode self-supporting film 42, the negative electrode film 12 is formed. The positive electrode self-supporting film 46 is a member that becomes the basis of a plurality of positive electrode films 16. By cutting the positive electrode self-supporting film 46, the positive electrode film 16 is formed. Here, the negative electrode self-supporting film 42 and the positive electrode self-supporting film 46 mean films that are supported by themselves without requiring a support such as a current collector foil 14. The negative electrode self-supporting film 42 and the positive electrode self-supporting film 46 contain a binder for self-supporting. The binder is, for example, a resin such as cellulose and is preferably fibrillated by prior kneading.

[0022] In the second step, an opening 12A is formed in the negative electrode self-supporting film 42, and an opening 16A is formed in the positive electrode self-supporting film 46. For the formation of the openings 12A and 16A, for example, laser processing is used. The negative electrode self-supporting film 42 and the positive electrode self-supporting film 46 in which the openings 12A and 16A are formed are wound around a roll for the next step.

[0023] Figure 5 shows the third step. In the third step, first, a long foil 44, which is the original material for multiple current collector foils 14, is prepared. The long foil 44 is wound on a roll. Next, the negative electrode self-supporting film 42 is bonded to one side of the foil 44. As shown in Figure 5, a pressure bonding method using rollers is used for bonding. Furthermore, the positive electrode self-supporting film 46 is also bonded to the other side of the foil 44 by a pressure bonding method similar to that in Figure 5. Here, the negative electrode self-supporting film 42 and the positive electrode self-supporting film 46 are bonded to the foil 44 such that the opening 12A of the negative electrode self-supporting film 42 faces the opening 16A of the positive electrode self-supporting film 46 through the foil 44. This prepares the original material for the bipolar electrode sheet 10. The original material for the unipolar positive electrode sheet 10 and negative electrode sheet 10 is also manufactured by a pressure bonding method similar to that in Figure 5.

[0024] In the fourth step, the material that will form the electrode sheets 10 is cut to the size of each electrode sheet 10.

[0025] In the fifth step, an opening 14A is formed in each electrode sheet 10 on the current collector foil 14 exposed within the opening 12A of the negative electrode film 12, i.e., the negative electrode film 12. In the case of a unipolar positive electrode sheet 10, an opening 14A is formed on the current collector foil 14 exposed within the opening 16A of the positive electrode film 16.

[0026] In the sixth step, a separator 20 with an opening 20A formed therein is prepared.

[0027] In the seventh step, multiple electrode sheets 10 and multiple separators 20 are stacked alternately so that the openings 12A, 14A, 16A, and 20A are aligned in a line.

[0028] In the eighth step, the openings 14A of two adjacent current collector foils 14 are connected to each other by an adhesive layer 24. This defines the through holes 101 to 105.

[0029] In the ninth step, an electrolyte solution is injected between the electrode sheets 10, and the periphery of the multiple electrode sheets 10 and the multiple separators 20 is covered by the outer frame 30.

[0030] (Correspondence) Battery module 2 is an example of a "battery module". Multiple electrode sheets 10 and multiple separators 20 are examples of "multiple electrode sheets" and "multiple separators", respectively. Through holes 101 to 105 are an example of a "through hole". Electrolyte 50 and space S1 are examples of an "electrolyte" and "space", respectively. Negative electrode film 12, current collector foil 14, and positive electrode film 16 are examples of a "negative electrode film", "current collector foil", and "positive electrode film", respectively. Openings 12A, 14A, and 16A are examples of "openings". Central region R1, center C1, outer edge E1, and straight line L1 are examples of a "central region", "center", "outer edge", and "arbitrary straight line", respectively. Distances D1 and D2 are examples of "distances", and point P1 is an example of a "point". Negative electrode self-supporting film 42 and positive electrode self-supporting film 46 are examples of a "negative electrode self-supporting film" and "positive electrode self-supporting film", respectively. Openings 12A, 16A, and 14A are examples of the "first opening," "second opening," and "third opening," respectively.

[0031] The following points should be noted regarding the technology shown in the examples. The through holes 101, etc., may be located on the periphery of the central region R1, rather than in the central region R1.

[0032] There may be at least one bipolar electrode sheet 10. Multiple electrode sheets 10 may consist, for example, one unipolar positive electrode sheet 10, one bipolar electrode sheet 10, and one unipolar negative electrode sheet 10.

[0033] Furthermore, diameters A1 to A4 in Figure 2 are merely examples of diameters for openings 12A to 20A. For example, the diameter of opening 12A and the diameter of opening 16A may be the same. [Explanation of Symbols]

[0034] 2: Battery module, 10: Electrode sheet, 12: Negative electrode film, 12A: Aperture, 14: Current collector foil, 14A: Aperture, 16: Positive electrode film, 16A: Aperture, 20: Separator, 20A: Aperture, 24: Adhesive layer, 30: Outer frame, 42: Negative electrode self-supporting film, 44: Foil, 46: Positive electrode self-supporting film, 50: Electrolyte, 100~105: Through-hole, A1~A4: Diameter, C1: Center, D1, D2: Distance, E1: Outer edge, II: Range, L1: Linear, R1: Central region, S1: Space

Claims

1. Multiple electrode sheets, Multiple separators are stacked alternately with the aforementioned multiple electrode sheets, An electrolyte sealed between the plurality of electrode sheets, Equipped with, Through holes are formed that penetrate the plurality of electrode sheets and the plurality of separators. The aforementioned through-hole is in communication with the outside and is isolated from the space in which the electrolyte is sealed. Battery module.

2. The battery module according to claim 1, wherein the plurality of electrode sheets include at least one bipolar electrode sheet.

3. The bipolar electrode sheet comprises a current collector foil, a negative electrode film provided on one side of the current collector foil, and a positive electrode film provided on the other side of the current collector foil. Each of the current collector foil, the positive electrode film, and the negative electrode film has an opening through which the through hole passes. The openings of the negative electrode film and the positive electrode film are larger than the openings of the current collector foil. The battery module according to claim 2, wherein the opening of the negative electrode film is smaller than the opening of the positive electrode film.

4. When the battery module is viewed along the stacking direction of the plurality of electrode sheets, the through-hole is located in the central region of the battery module. The battery module according to any one of claims 1 to 3, wherein the central region is a set of points on any straight line extending radially from the center of the battery module toward the outer edge of the electrode sheet, where the distance to the center is shorter than the distance to the outer edge.

5. A method for manufacturing a battery module according to claim 3, The process includes preparing the aforementioned bipolar electrode sheet, The step of preparing the bipolar electrode sheet is as follows: A step of forming a first opening in a self-supporting negative electrode film containing a negative electrode active material, A step of forming a second opening larger than the first opening in a positive electrode self-supporting film containing positive electrode active material, The steps include: joining the negative electrode self-supporting film to one side of the current collector foil and joining the positive electrode self-supporting film to the other side of the current collector foil, such that the first opening of the negative electrode self-supporting film faces the second opening of the positive electrode self-supporting film via the current collector foil; The process includes forming a third opening smaller than the first opening in the current collector foil exposed within the second opening of the negative electrode self-supporting film. Manufacturing method.

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