Current collector for bipolar electrodes

Abstract

The present invention relates to a current collector for a bipolar electrode. The current collector for a bipolar electrode includes an Al foil provided on one surface, and a Cu foil provided on the other surface and joined to the Al foil. 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.

Description

Technical Field

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

[0002] Japanese Unexamined Patent Application Publication No. 2022-075283 (JP 2022-075283 A) discloses a current collector for a bipolar electrode, which uses an Al foil on the cathode side and a Cu foil on the anode side. Summary of the Invention

[0003] As disclosed in JP 2022-075283 A, the current collector in which Al foil and Cu foil are laminated together requires cutting the ends after foil formation to obtain a specified size. However, when the ends of the Al foil and Cu foil are cut simultaneously, foreign matter composed of Cu (hereinafter referred to as "Cu foreign matter") may adhere to the Al foil. When Cu foreign matter adheres to the Al foil, Cu elution may lead to Li deposition, which may result in self-discharge failure.

[0004] In view of the foregoing, this disclosure has been made, and the purpose of this disclosure is to provide a current collector for a bipolar electrode that can suppress the generation of Cu foreign matter during cutting.

[0005] The current collector for a bipolar electrode according to this disclosure includes: an Al foil disposed on one surface; and a Cu foil disposed on another surface and bonded to the Al foil. The area S1 of the Al foil and the area S2 of the Cu foil are related as S1 > S2. The Al foil protrudes from the end of the Cu foil.

[0006] According to this disclosure, when cutting the current collector to a specified size, only the Al foil protruding from the end of the Cu foil can be cut, without cutting the Cu foil itself. Therefore, the generation of Cu foreign matter can be suppressed. Attached Figure Description

[0007] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, in which the same symbols denote the same elements, and wherein: Figure 1 This is a diagram illustrating the configuration of a current collector for a bipolar electrode according to an embodiment, wherein part (a) is a cross-sectional view and part (b) is a plan view; Figure 2 This is a plan view showing an example of a sealing member disposed on a protrusion of an Al foil in a current collector for a bipolar electrode according to an embodiment; and Figure 3It is a diagram showing the configuration of a current collector for a bipolar electrode according to the related art, wherein part (a) is a cross-sectional view and part (b) is a plan view. Detailed Implementation

[0008] The following description, with reference to the accompanying drawings, describes a current collector for a bipolar electrode according to embodiments of the present disclosure. The components in the following embodiments include those that are replaceable and readily available to those skilled in the art, or substantially the same components.

[0009] Reference Figure 1 and Figure 2 This describes a current collector for bipolar electrodes according to an embodiment. The current collector for bipolar electrodes according to the embodiment is, for example, a component constituting an energy storage module to be installed in a vehicle. Examples of vehicles to which an energy storage module is to be installed include hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs).

[0010] Figure 1 This is a diagram illustrating the configuration of a current collector 1 for a bipolar electrode according to an embodiment, wherein part (a) is a cross-sectional view of the current collector 1 from the side, and part (b) is a plan view of the current collector 1 from the top. The current collector 1 includes an Al foil 11, a Cu foil 12, and an adhesive layer 13.

[0011] The Al foil 11 is made of aluminum. The Al foil 11 is disposed on one surface of the current collector 1. The Cu foil 12 is made of copper. The Cu foil 12 is disposed on another surface of the current collector 1 opposite to the first surface. The Cu foil 12 is bonded to the Al foil 11 via an adhesive layer 13.

[0012] The adhesive layer 13 is made, for example, of a conductive adhesive comprising an adhesive and a conductive component. The components of the adhesive are not particularly limited, but may be curable resins, such as olefin resins or acrylic resins. The conductive component is not particularly limited, as long as its conductivity is higher than that of the adhesive. Examples of conductive components include metal particles, alloy particles such as aluminum-magnesium alloy particles, metal oxide particles or metal particles coated with precious metals, non-conductive particles coated with precious metals, non-conductive particles plated with metal, and carbon particles.

[0013] Figure 3 This is a diagram illustrating the configuration of a current collector 101 in the related art, wherein part (a) is a cross-sectional view of the current collector 101 from the side, and part (b) is a plan view of the current collector 101 from the top. The current collector 101 includes an Al foil 11, a Cu foil 112, and an adhesive layer 113.

[0014] In current collector 101, such as Figure 3As shown in part (a), Al foil 11 and Cu foil 112 have equal areas. Therefore, when the right and left ends of Al foil 11 and Cu foil 112 are cut to the specified dimensions after the foils are formed, Cu foreign matter may adhere to Al foil 11, which may lead to self-discharge failure.

[0015] In the current collector 1 according to the embodiment, such as Figure 1 As shown in part (a), the area of ​​Cu foil 12 is smaller than the area of ​​Al foil 11. That is, when the area of ​​Al foil 11 is S1 and the area of ​​Cu foil 12 is S2, the relationship between areas S1 and S2 is "S1>S2". Therefore, Al foil 11 protrudes from the end of Cu foil 12.

[0016] Figure 1 The shape and area of ​​the Cu foil 12 shown are merely examples. The Cu foil 12 can have any configuration, as long as the positions of the two ends in the X direction are inside the cut position (see dashed line). The Al foil 11 has a configuration in which the positions of the two ends in the X direction protrude outward beyond the two ends of the Cu foil 12 and are outside the cut position (see dashed line).

[0017] exist Figure 1 In the current collector 1 shown, the adhesive layer 13 has 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 also protrudes from the end of the adhesive layer 13.

[0018] The protrusion 111 of the Al foil 11 extending from the end of the Cu foil 12 can be covered, for example, by a sealing member 14, such as... Figure 2 As shown. The sealing member 14 covers, for example, the entire protrusion 111 (top surface, side surface, and bottom surface) and the side surface of the adhesive layer 13. Considering the coverage by the sealing member 14, the amount by which the protrusion 111 protrudes from the end of the Cu foil 12 is preferably at least 20 mm or less, and more preferably 10 mm or less.

[0019] The composition of the sealing member 14 is not particularly limited, but it can be a thermoplastic resin, such as acid-modified polyethylene, acid-modified polypropylene, polyethylene, or polypropylene. By covering the protrusion 111 with the sealing member 14 in this manner, the Li alloying reaction of the Al foil 11 caused by charging and discharging can be suppressed. By covering the side surface of the adhesive layer 13 with the sealing member 14, for example when the adhesive layer 13 contains a water-based adhesive, the release of moisture from the adhesive layer 13 can be suppressed.

[0020] In the current collector for bipolar electrodes according to the above embodiment, when the current collector 1 is cut to a predetermined size, only the Al foil 11 protruding from the end of the Cu foil 12 can be cut, without cutting the Cu foil 12. Therefore, the generation of Cu foreign matter can be suppressed.

[0021] In the current collector for a bipolar electrode according to this embodiment, the Al foil 11 protruding from the end of the Cu foil 12 is covered by a sealing member 14, thereby suppressing the Li alloying reaction of the Al foil 11 caused by charging and discharging. In the current collector for a bipolar electrode according to this embodiment, the amount of Cu foil 12, which is more expensive than Al foil 11, can be reduced, and the waste remaining during cutting is only Al foil 11. Therefore, recyclability is improved.

[0022] Other effects and variations can be readily derived by those skilled in the art. Therefore, the broader aspects of the invention are not limited to the specific details and representative embodiments shown and described above. Consequently, various modifications can be made without departing from the spirit or scope of the general concept of the invention as defined by the appended claims and their equivalents.

Claims

1. A current collector for a bipolar electrode, the current collector comprising: Al foil, the Al foil being disposed on a surface; as well as Cu foil, which is disposed on another surface and bonded to 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 end of the Cu foil.

2. The current collector for a bipolar electrode according to claim 1, wherein The protrusion of the Al foil from the end of the Cu foil is covered by a sealing member.

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