Current collector for bipolar electrodes

Abstract

To provide a current collector for bipolar electrodes that can suppress the generation of copper foreign matter during cutting. [Solution] The current collector for the bipolar electrode comprises an Al foil provided on one side and a Cu foil provided on the other side and joined to the Al foil, wherein the relationship between the area S1 of the Al foil and the area S2 of the Cu foil is S1 > S2, and the Al foil protrudes from the edge of the Cu foil.

Description

Technical Field

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[0001] This disclosure relates to a current collector for a bipolar electrode.

Background Art

[0002] Patent Document 1 discloses a current collector for a bipolar electrode using an Al foil on the positive electrode side and a Cu foil on the negative electrode side.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] According to this disclosure, when cutting the current collector to a specified size, it is possible to cut only the Al foil protruding from the end of the Cu foil without cutting the Cu foil itself, thereby suppressing the generation of Cu foreign matter. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows the configuration of a current collector for a bipolar electrode according to an embodiment, where (a) is a cross-sectional view and (b) is a plan view. [Figure 2] Figure 2 is a plan view showing an example of a sealing member provided on a protruding portion of the Al foil in a current collector for a bipolar electrode according to the embodiment. [Figure 3] Figure 3 shows the configuration of a conventional current collector for bipolar electrodes, where (a) is a cross-sectional view and (b) is a plan view. [Modes for carrying out the invention]

[0009] A current collector for a bipolar electrode according to the embodiments of this disclosure will be described with reference to the drawings. Note that the components in the following embodiments include those that are easily substituted or substantially identical to those that are easily substituted by those skilled in the art.

[0010] A current collector for a bipolar electrode according to the embodiment will be described with reference to Figures 1 and 2. The current collector for a bipolar electrode according to the embodiment is, for example, a component of an energy storage module mounted on a vehicle. Examples of vehicles on which this energy storage module is mounted include hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs).

[0011] Figure 1 shows the configuration of a current collector 1 for a bipolar electrode according to an embodiment, where (a) is a cross-sectional view of the current collector 1 viewed from the side, and (b) is a plan view of the current collector 1 viewed from above. The current collector 1 comprises an Al foil 11, a Cu foil 12, and an adhesive layer 13.

[0012] The Al foil (aluminum foil) 11 is made of aluminum. The Al foil 11 is provided on one side of the current collector 1. The Cu foil (copper foil) 12 is made of copper. The Cu foil 12 is provided on the other side of the current collector 1, opposite to the one side. The Cu foil 12 is bonded to the Al foil 11 via an adhesive layer 13.

[0013] The adhesive layer 13 is composed of a conductive adhesive, for example, an adhesive and a conductive component. The components of the adhesive are not particularly limited, but can be composed of curable resins such as olefin resins and acrylic resins. The conductive component is not particularly limited as long as it has higher conductivity than the adhesive. Examples of conductive components include metal particles, alloy particles such as aluminum-magnesium alloys, metal oxide particles or particles coated with precious metals, non-conductive particles coated with precious metals, non-conductive particles plated with metal, and carbon particles.

[0014] Here, Figure 3 shows the configuration of a conventional current collector 101, where (a) is a cross-sectional view of the current collector 101 seen from the side, and (b) is a plan view of the current collector 101 seen from above. The current collector 101 comprises an Al foil 11, a Cu foil 112, and an adhesive layer 113.

[0015] In the current collector 101, as shown in Figure 3(a), the Al foil 11 and Cu foil 112 are composed of the same area. Therefore, if the left and right ends of the Al foil 11 and Cu foil 112 are cut to achieve the specified dimensions after foil formation, Cu foreign matter may adhere to the Al foil 11, potentially causing self-discharge failure.

[0016] Therefore, in the current collector 1 according to this embodiment, as shown in Figure 1(a), the area of ​​the Cu foil 12 is made smaller than the area of ​​the Al foil 11. That is, if the area of ​​the Al foil 11 is S1 and the area of ​​the Cu foil 12 is S2, the relationship between the areas S1 and S2 is "S1 > S2". As a result, the Al foil 11 protrudes from the end of the Cu foil 12.

[0017] Note that the shape and area of ​​the Cu foil 12 shown in Figure 1 are just examples. The Cu foil 12 only needs to be configured such that the positions of both ends in the X direction are inside the cutting position (see dashed line). In contrast, the Al foil 11 is configured such that the positions of both ends in the X direction protrude outward more than the ends of both ends of the Cu foil 12 and are outside the cutting position (see dashed line).

[0018] Furthermore, in the current collector 1 shown in Figure 1, the adhesive layer 13 is also constructed with the same shape and area as the Cu foil 12. That is, the area of ​​the adhesive layer 13 is smaller than the area of ​​the Al foil 11. Therefore, the Al foil 11 protrudes from the edges of the adhesive layer 13.

[0019] Here, the protruding portion 111 of the Al foil 11 that extends from the end of the Cu foil 12 may be covered by a sealing member 14, for example, as shown in Figure 2. The sealing member 14 covers, for example, the entire protruding portion 111 (top, side, and bottom surfaces), as well as the side surfaces of the adhesive layer 13. Considering that it will be covered by the sealing member 14, the amount of the protrusion 111 from the end of the Cu foil 12 is preferably at least 20 mm, and more preferably 10 mm or less.

[0020] The components of the seal member 14 are not particularly limited. For example, thermoplastic resins such as acid-modified polyethylene, acid-modified polypropylene, polyethylene, and polypropylene can be used. Thus, by covering the protruding portion 111 with the seal member 14, the Li alloying reaction of the Al foil 11 due to charge and discharge can be suppressed. Further, by covering the side surface of the adhesive layer 13 with the seal member 14, for example, when the adhesive layer 13 contains an aqueous adhesive, the release of moisture in the adhesive layer 13 can be suppressed.

[0021] According to the current collector for a bipolar electrode according to the embodiment described above, when cutting the current collector 1 to a specified size, only the Al foil 11 protruding from the end of the Cu foil 12 can be cut without cutting the Cu foil 12. Thereby, the generation of Cu foreign matter can be suppressed.

[0022] Further, according to the current collector for a bipolar electrode according to the embodiment, by covering the Al foil 11 protruding from the end of the Cu foil 12 with the seal member 14, the Li alloying reaction of the Al foil 11 due to charge and discharge can be suppressed. Furthermore, according to the current collector for a bipolar electrode according to the embodiment, the amount of use of the Cu foil 12, which is more expensive than the Al foil 11, can be reduced, and since the end material at the time of cutting is only the Al foil 11, the recyclability is improved.

[0023] Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various changes can be made without departing from the spirit or scope of the general inventive concept defined by the appended claims and their equivalents.

Explanation of Reference Numerals

[0024] 1, 101 Current collector 11 Al foil 111 Protruding portion 12, 112 Cu foil 13, 113 Adhesive layer 14. Sealing member

Claims

1. Al foil provided on one side, A Cu foil is provided on the other side and is bonded to the Al foil, Equipped with, The relationship between the area S1 of the Al foil and the area S2 of the Cu foil is S1 > S2. The Al foil protrudes from the end of the Cu foil. A current collector for bipolar electrodes.

2. The current collector for a bipolar electrode according to claim 1, wherein the protruding portion of the Al foil that protrudes from the end of the Cu foil is covered with a sealing member.

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