Current collector for bipolar electrodes and recycling method for current collector for bipolar electrodes

Abstract

To provide a current collector for bipolar electrodes and a method for recycling a current collector for bipolar electrodes that facilitates the separation of dissimilar metals constituting the current collector and improves recyclability. [Solution] The current collector for the bipolar electrode comprises a first metal foil provided on one side, a second metal foil of a different type from the first metal foil provided on the other side, and a conductive adhesive layer interposed between the first and second metal foils to bond them together, wherein the outer edge of the conductive adhesive layer is a dehydrating adhesive layer that undergoes a dehydration reaction when heated to 100°C or higher.

Description

Technical Field

[0006] , , , ,

[0001] The present disclosure relates to a current collector for a bipolar electrode and a method for recycling the current collector for a bipolar electrode.

Background Art

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

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, when recycling a current collector in which dissimilar metals are bonded together as disclosed in Patent Document 1, it is necessary to peel and separate these dissimilar metals. However, since the dissimilar metals constituting the current collector are configured with the same area, there is no gripping margin for peeling both of them, and separation may be difficult in some cases.

[0005] The present disclosure has been made in view of the above, and an object thereof is to provide a current collector for a bipolar electrode and a method for recycling the current collector for a bipolar electrode that can facilitate the separation of dissimilar metals constituting the current collector and improve the recyclability. [[ID=4i]]

Means for Solving the Problems

[0006] The current collector for a bipolar electrode according to this disclosure comprises a first metal foil provided on one side, a second metal foil of a different type from the first metal foil provided on the other side, and a conductive adhesive layer interposed between the first metal foil and the second metal foil to bond them together, wherein the outer edge of the conductive adhesive layer is a dehydrating adhesive layer that undergoes a dehydration reaction when heated to 100°C or higher.

[0007] The method for recycling a current collector for a bipolar electrode according to this disclosure involves heating the current collector for the bipolar electrode to 100°C or higher, thereby vaporizing or expanding the dehydrating adhesive layer provided on the outer edge of the conductive adhesive layer interposed between the first metal foil and the second metal foil, and creating a gap between the first metal foil and the second metal foil. [Effects of the Invention]

[0008] According to this disclosure, it is possible to facilitate the separation of dissimilar metals that constitute the current collector and improve recyclability. [Brief explanation of the drawing]

[0009] [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 cross-sectional view illustrating a recycling method for a current collector for a bipolar electrode according to an 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]

[0010] A current collector for a bipolar electrode and a recycling method for 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 replaceable or substantially identical to those that are replaceable by those skilled in the art.

[0011] (Current collector for bipolar electrodes) A current collector for a bipolar electrode according to the embodiment will be described with reference to Figures 1 and 3. 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).

[0012] Figure 1(a) is a cross-sectional view of the current collector 1 for a bipolar electrode according to the embodiment, viewed from the side. Figure 1(b) is a plan view of the conductive adhesive layer 13 of the current collector 1, viewed from position AA in Figure 1(a). The current collector 1 comprises an Al foil 11, a Cu foil 12, and a conductive adhesive layer 13.

[0013] 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, which is the side opposite to the one side. The Cu foil 12 is bonded to the Al foil 11 via a conductive adhesive layer 13.

[0014] The conductive adhesive layer 13 is interposed between the Al foil 11 and the Cu foil 12, bonding them together. The conductive 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, particles coated with precious metals on non-conductive particles, particles plated with metal on non-conductive particles, and carbon particles.

[0015] Thus, the current collector 1 is composed of an Al foil 11 which is a first metal foil, a Cu foil 12 which is a second metal foil of a different type from the first metal foil, and a conductive adhesive layer 13 that bonds the two.

[0016] Here, FIG. 3 is a diagram showing the configuration of a conventional current collector 101. (a) of FIG. 3 is a cross-sectional view of the current collector 101 seen from the side. Further, (b) of FIG. 3 is a plan view of the conductive adhesive layer 113 of the current collector 101 seen from the position A-A of (a) of FIG. 3. The current collector 101 includes an Al foil 11, a Cu foil 12, and a conductive adhesive layer 113.

[0017] In the current collector 101, as shown in (a) of FIG. 3, the Al foil 11 and the Cu foil 12 are configured with the same area. Therefore, there is no gripping margin for peeling the Al foil 11 and the Cu foil 12 during the recycling of the current collector 101, and there is a problem of poor recyclability.

[0018] Therefore, in the current collector 1 according to the embodiment, as shown in FIG. 1, a part of the conductive adhesive layer 13 is composed of a dehydrating adhesive layer 132 in which a dehydration reaction occurs by heating at 100° C. or higher. Hereinafter, the specific configuration of the conductive adhesive layer 13 will be described.

[0019] The conductive adhesive layer 13 is composed of a non-dehydrating adhesive layer 131 and a dehydrating adhesive layer 132. The non-dehydrating adhesive layer 131 is provided in a portion other than the outer edge portion of the conductive adhesive layer 13. Further, the non-dehydrating adhesive layer 131 is composed of an adhesive in which a dehydration reaction does not occur by heating at 100° C. or higher.

[0020] The dehydrating adhesive layer 132 is provided at the outer edge portion of the conductive adhesive layer 13. Further, as shown in (b) of FIG. 1, the dehydrating adhesive layer 132 is provided only on one side of the four sides of the outer edge portion of the conductive adhesive layer 13. Also, the width W of the dehydrating adhesive layer 132 is preferably at least 5 mm or more, and more preferably 10 mm or more.

[0021] Further, the dehydration adhesive layer 132 is composed of an adhesive (e.g., an aqueous adhesive) that undergoes a dehydration reaction by heating at 100°C or higher. Examples of the aqueous adhesive include aqueous curable resins such as water-dispersed olefin resins.

[0022] (Recycling method for current collector of bipolar electrode) A recycling method for the current collector of the bipolar electrode according to the embodiment will be described while referring to FIG. 2.

[0023] In the recycling method of the current collector 1, for example, as shown in (a) of FIG. 2, the dehydration adhesive layer 132 provided at the outer edge of the conductive adhesive layer 13 interposed between the Al foil 11 (first metal foil) and the Cu foil 12 (second metal foil) is heated to 100°C or higher. At that time, only the dehydration adhesive layer 132 may be targeted for heating, or the entire current collector 1 may be heated as necessary.

[0024] By heating the dehydration adhesive layer 132 in this way, the dehydration adhesive layer 132 is vaporized or expanded. Then, by vaporizing or expanding the dehydration adhesive layer 132, as shown in (b) of FIG. 2, for example, the space between the Al foil 11 and the Cu foil 12 is peeled off to generate a gap.

[0025] In the recycling method of the current collector 1, by the dehydration reaction during heating as shown in (a) of FIG. 2, only one side of the four sides of the current collector 1 is vaporized or expanded, and a gap is generated between the Al foil 11 and the Cu foil 12, thereby forming a gripping margin when peeling them off. Then, in the recycling method of the current collector 1, the Al foil 11 and the Cu foil 12 are separated based on the gap of the dehydration adhesive layer 132.

[0026] In the recycling method for the current collector 1, it is sufficient to heat it to 100°C or higher, where a dehydration reaction and water vaporization occur. Therefore, compared to conventional recycling methods that involve heating and decomposing the conductive adhesive layer at high temperatures of, for example, 400°C or higher, costs can be reduced. Furthermore, in the recycling method for the current collector 1, by providing the dehydrating adhesive layer 132 that causes dehydration only on one side of the outer edge of the conductive adhesive layer 13, the impact can be minimized even if dehydration occurs during the operation of the energy storage module, for example.

[0027] The current collector for bipolar electrodes according to the embodiment described above facilitates the separation of dissimilar metals constituting the current collector 1, thereby improving recyclability. Furthermore, according to the recycling method for the current collector for bipolar electrodes according to the embodiment, by heating the current collector 1 to 100°C or higher, a dehydration reaction causes only the dehydration adhesive layer 132 provided on one side of the current collector 1 to vaporize or expand, forming a gap between the dissimilar metals (Al foil 11, Cu foil 12). This creates a gripping surface when peeling off the Al foil 11 and Cu foil 12, making their separation easier and improving recyclability.

[0028] Further effects and modifications can be readily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents. [Explanation of symbols]

[0029] 1,101 Current collector 11 Al foil 12 Cu foil 13,113 Conductive adhesive layer 131 Non-dehydrated adhesive layer 132 Dehydration adhesive layer

Claims

1. A first metal foil provided on one side, A second metal foil of a different type from the first metal foil is provided on the other side, A conductive adhesive layer is interposed between the first metal foil and the second metal foil to bond them together, Equipped with, The outer edge of the conductive adhesive layer is a dehydrated adhesive layer that undergoes a dehydration reaction when heated to 100°C or higher. A current collector for bipolar electrodes.

2. A method for recycling a current collector for a bipolar electrode, comprising heating the current collector for a bipolar electrode according to claim 1 to 100°C or higher, thereby vaporizing or expanding a dehydrating adhesive layer provided on the outer edge of a conductive adhesive layer interposed between a first metal foil and a second metal foil, and creating a gap between the first metal foil and the second metal foil.

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