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

Abstract

The present invention relates to a current collector for a bipolar electrode and a recycling method of a current collector for a bipolar electrode. The current collector for a bipolar electrode includes a first metal foil disposed on one face, a second metal foil different in kind from the first metal foil and disposed on the other face, and a conductive adhesive layer interposed between the first metal foil and the second metal foil so as to bind both the first metal foil and the second metal foil together, wherein an outer edge of the conductive adhesive layer is a dehydration adhesive layer that undergoes a dehydration reaction when heated to 100°C or higher.

Description

Technical Field

[0001] This disclosure relates to a current collector for a bipolar electrode and a method for recycling the 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] When recycling current collectors that are bonded to different types of metals, as disclosed in JP 2022-075283 A, it is necessary to peel and separate these different types of metals. However, the different types of metals constituting the current collector are configured to have the same area, and there is no clamping allowance for peeling the two pieces apart, which may make separation difficult.

[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 and a method for recycling a current collector for a bipolar electrode, the current collector for a bipolar electrode being able to facilitate the separation of different types of metals constituting the current collector and improve recyclability.

[0005] According to the present disclosure, a current collector for a bipolar electrode includes a first metal foil disposed on one side, a second metal foil of a different type disposed on the other side, and a conductive adhesive layer disposed between the first metal foil and the second metal foil to bond the first metal foil and the second metal foil together, wherein 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.

[0006] The method for recycling a current collector for a bipolar electrode according to this disclosure includes: heating the current collector to 100°C or higher, causing the dehydrated adhesive layer disposed on the outer edge of a conductive adhesive layer between a first metal foil and a second metal foil to evaporate or expand, thereby creating a gap between the first metal foil and the second metal foil.

[0007] According to this disclosure, the separation of different types of metals constituting the current collector is facilitated, and recyclability can be improved. Attached Figure Description

[0008] 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 reference numerals denote the same elements, and wherein: Figure 1AThis is a cross-sectional view showing the configuration of the current collector for the bipolar electrode according to an embodiment; Figure 1B This is a plan view showing the configuration of the current collector for the bipolar electrode according to an embodiment; Figure 2A This is a cross-sectional view used to describe a method for recycling a current collector for a bipolar electrode according to an embodiment; Figure 2B This is a cross-sectional view used to describe a method for recycling a current collector for a bipolar electrode according to an embodiment; Figure 3A This is a cross-sectional view showing the conventional configuration of a current collector for a bipolar electrode; and Figure 3B This is a plan view showing the configuration of a conventional current collector for a bipolar electrode. Detailed Implementation

[0009] A current collector for a bipolar electrode and a method for recycling a current collector for a bipolar electrode according to embodiments of the present disclosure will be described with reference to the accompanying drawings. Note that the components in the following embodiments include components that are readily available and replaceable or substantially the same as those skilled in the art.

[0010] Current collector for bipolar electrodes

[0011] Reference Figure 1A , Figure 1B , Figure 3A and Figure 3B This describes a current collector for bipolar electrodes according to an embodiment. The current collector for bipolar electrodes according to the embodiment is a component constituting an energy storage module installed, for example, in a vehicle. Vehicles equipped with this energy storage module include, for example, hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), etc.

[0012] Figure 1A This is a cross-sectional view of the current collector 1 for a bipolar electrode according to an embodiment, viewed from the side. Furthermore, Figure 1B From Figure 1A The image shows a plan view of the conductive adhesive layer 13 of the current collector 1, observed from position AA. The current collector 1 includes an Al foil 11, a Cu foil 12, and a conductive adhesive layer 13.

[0013] The Al foil 11 is made of aluminum. Furthermore, the Al foil 11 is disposed on one side of the current collector 1. The Cu foil 12 is made of copper. Furthermore, the Cu foil 12 is disposed on the other side of the current collector 1, which is the side opposite to the first side of the current collector 1. In addition, the Cu foil 12 is bonded to the Al foil 11 via a conductive adhesive layer 13.

[0014] A conductive adhesive layer 13 is situated between the Al foil 11 and the Cu foil 12 to bond the two together. The conductive adhesive layer 13 is, for example, made of a conductive adhesive comprising an adhesive and a conductive component. The adhesive is not particularly limited in its composition, but can be made, for example, from a curable resin such as an olefin-based resin, an acrylic-based resin, etc. 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 alloys, particles obtained by coating metal oxide particles or metal particles with a noble metal, particles obtained by coating non-conductive particles with a noble metal, particles obtained by plating non-conductive particles with a metal, carbon particles, etc.

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

[0016] Now, Figure 3A and Figure 3B This is a diagram showing the configuration of the current collector 101 according to conventional technology. Figure 3A This is a cross-sectional view of the current collector 101 viewed from the side. Furthermore, Figure 3B From Figure 3A The image shows a plan view of the conductive adhesive layer 113 of the current collector 101 as observed from position AA. The current collector 101 includes an Al foil 11, a Cu foil 12, and a conductive adhesive layer 113.

[0017] like Figure 3A As shown, the current collector 101 is made of Al foil 11 and Cu foil 12 configured to have the same area. Therefore, when the current collector 101 is recycled, there is no clamping allowance for peeling the Al foil 11 and Cu foil 12 apart, which leads to poor recyclability.

[0018] Therefore, as Figure 1A and Figure 1B As shown, in the current collector 1 according to the embodiment, a portion of the conductive adhesive layer 13 is configured as a dehydrated adhesive layer 132, which undergoes a dehydration reaction when heated to 100°C or higher. The specific configuration of the conductive adhesive layer 13 is described below.

[0019] The conductive adhesive layer 13 is composed of a non-dehydrated adhesive layer 131 and a dehydrated adhesive layer 132. The non-dehydrated adhesive layer 131 is disposed on the conductive adhesive layer 13 except for its outer edge portion. Moreover, the non-dehydrated adhesive layer 131 is made of an adhesive that does not undergo a dehydration reaction when heated to 100°C or higher.

[0020] The dehydrated adhesive layer 132 is disposed on the outer edge of the conductive adhesive layer 13. Furthermore, as... Figure 1BAs shown, the dehydrated adhesive layer 132 is disposed on only one of the four sides of the outer edge of the conductive adhesive layer 13. Moreover, the width W of the dehydrated adhesive layer 132 is preferably at least 5 mm or more, and more preferably 10 mm or more.

[0021] Furthermore, the dehydrated adhesive layer 132 is made of an adhesive (e.g., a water-based adhesive) that undergoes a dehydration reaction when heated to 100°C or higher. Examples of water-based adhesives include water-based curable resins, such as water-dispersible olefin-based resins, etc.

[0022] Method for recovering current collectors for bipolar electrodes

[0023] Reference Figure 2A and Figure 2B A method for recycling a current collector for a bipolar electrode is described according to an embodiment.

[0024] In the method for recovering current collector 1, for example, such as Figure 2A As shown, the dehydrated adhesive layer 132 disposed on the outer edge of the conductive adhesive layer 13 between the Al foil 11 (first metal foil) and the Cu foil 12 (second metal foil) is heated to 100°C or higher. At this time, heating can be performed by targeting only the dehydrated adhesive layer 132, or the entire current collector 1 can be heated as needed.

[0025] Heating the dehydrated adhesive layer 132 in this manner causes it to evaporate or expand. The evaporation or expansion of the dehydrated adhesive layer 132 then causes the Al foil 11 and Cu foil 12 to peel apart from each other, thereby creating a gap therebetween, for example, as... Figure 2B As shown.

[0026] In the recycling method used for current collector 1, such as Figure 2A As shown, a dehydration reaction occurs during heating, causing only one of the four sides of the current collector 1 to evaporate or expand, thereby creating a gap between the Al foil 11 and the Cu foil 12, and thus forming a clamping allowance for peeling the two apart. In the recycling method for the current collector 1, the Al foil 11 and the Cu foil 12 are separated from each other, starting from the gap in the dehydrated adhesive layer 132.

[0027] In the recycling method for current collector 1, the current collector only needs to be heated to 100°C or higher, at which point a dehydration reaction and water evaporation occur. This reduces costs compared to conventional recycling methods, such as heating the conductive adhesive layer to 400°C or higher for decomposition. Furthermore, in the recycling method for current collector 1, providing a dehydrated adhesive layer 132 that has undergone dehydration on only one side of the outer edge of the conductive adhesive layer 13 minimizes the effects even if dehydration occurs, for example, during the operation of the energy storage module.

[0028] According to the current collector for bipolar electrodes of the above embodiment, different types of metals constituting the current collector 1 can be easily separated, thereby improving recyclability. Furthermore, according to the recycling method for the current collector for bipolar electrodes of this embodiment, heating the current collector 1 to 100°C or higher only causes the dehydrated adhesive layer 132 disposed on one side of the current collector 1 to evaporate or expand due to a dehydration reaction, thereby creating a gap between different types of metals (Al foil 11 and Cu foil 12). This allows for the formation of a clamping allowance when peeling off the Al foil 11 and Cu foil 12, thereby promoting their separation and improving recyclability.

[0029] Those skilled in the art can readily derive further effects and variations. Therefore, the broader aspects of the invention are not limited to the specific details and representative embodiments expressed 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: A first metal foil, the first metal foil being disposed on a surface; A second metal foil, which is of a different type than the first metal foil, and which is disposed on another side; as well as A conductive adhesive layer is provided between the first metal foil and the second metal foil to bond the two metal foils together. The outer edge of the conductive adhesive layer is a dehydrated adhesive layer, which undergoes a dehydration reaction when heated to 100°C or higher.

2. A method for recycling a current collector for a bipolar electrode, the recycling method comprising: The current collector according to claim 1 is heated to 100°C or higher, causing the dehydrated adhesive layer disposed on the outer edge of the conductive adhesive layer between the first metal foil and the second metal foil to evaporate or expand, thereby creating a gap between the first metal foil and the second metal foil.

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