Method and device for dismantling laminated body

Abstract

To provide a method for dismantling a laminated body, which can separate a thin film and a bonded layer bonded to a surface of the thin film of a laminated body constituted of the thin film and the bonded layer, while suppressing the thin film and the bonded layer from mixing with each other.SOLUTION: A method for dismantling a laminated body includes: a step (a) of preparing a laminated body constituted of a thin film made of an electrical conductor and a bonded layer bonded to a surface of the film; a step (b) of contacting a positive electrode and a negative electrode with the laminated body; and a step (c) of applying high-voltage pulse to a space between the electrodes, where the high-voltage pulse generates, in the thin film, Joule heat enough to dissolve and melt substances bonding the thin film to the bonded layer, which exist in the vicinity of an interface between the thin film and the layer, and pulse power generated by application of the high-voltage pulse separates the thin film from the bonded layer, so that the laminated body is dismantled into the thin film and the bonded layer.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method and an apparatus for dismantling a laminate, and more particularly to a method and an apparatus for dismantling, for example, electrodes of a lithium ion battery so as to efficiently recover and reuse the materials that constitute them. [Background technology]

[0002] The importance of recovering and reusing useful resources from electronic devices such as home appliances and communication terminals has been increasing in recent years, and efficient methods for dismantling and dismantling items are essential for recovering and reusing resources. For example, the positive electrode material of lithium-ion batteries contains useful substances and elements such as cobalt, and since lithium-ion batteries are currently widely used and widely used as batteries, there is a strong demand for the establishment of efficient methods for recovering and reusing useful substances and elements after their disposal.

[0003] Some of the present inventors have previously proposed methods for separating and recovering cobalt from the positive electrode material of lithium-ion batteries. For example, they have proposed a method for recovering cobalt by combining heating and crushing (JP Patent Publication No. 2016-89209 (Patent Document 1)), and a method for separating cobalt and aluminum by combining low-temperature heating and physical sorting (JP Patent Publication No. 2017-37807 (Patent Document 2)). These methods can efficiently recover cobalt, but there is still a demand for methods that are more efficient and have a lower environmental impact. In particular, there is a demand for mechanical dismantling techniques that can separate with high accuracy the parts that contain useful substances and elements that are to be dismantled.

[0004] On the other hand, various proposals have been made to decompose and destroy objects by applying high voltage pulses. JP 2020-69454 A (Patent Document 3) discloses a method of applying a pulsed high voltage between electrodes to separate and dismantle an object into an insulator and a conductor by arc discharge, and a method of dismantling by wire explosion. However, this document does not disclose or suggest the use of Joule heat by applying a high voltage pulse to a thin film. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-89209 A [Patent Document 2] JP 2017-37807 A [Patent Document 3] JP 2020-69454 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors have now discovered that by applying a high voltage pulse to a laminate consisting of a thin film made of a conductor and a layer bonded to the surface of the thin film, it is possible to separate the thin film and the layer bonded to the surface of the thin film while minimizing contamination of the two. The present invention is based on this discovery.

[0007] Therefore, an object of the present invention is to provide a method for dismantling a laminate, which can separate a laminate consisting of a thin film and a layer attached to the surface of the thin film while suppressing mutual contamination of the thin film and the layer. [Means for solving the problem]

[0008] The method for dismantling a laminate according to the present invention comprises the steps of: (a) preparing a laminate comprising a thin film made of a conductor and an adhesive layer bonded to the surface of the thin film; (b) contacting the laminate with a positive electrode and a negative electrode; and (c) applying a high voltage pulse between the electrodes; comprising wherein the high voltage pulse generates Joule heat in the thin film sufficient to decompose and melt a substance that bonds the thin film and the layer and is present in the vicinity of the interface between the thin film and the layer; and The thin film and the layer are separated by pulse power generated by application of the high voltage pulse, and the laminate is decomposed into the thin film and the adhesive layer. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic diagram of one embodiment in which a positive electrode and a negative electrode are in surface contact with a laminate. [Diagram 2] FIG. 2 is a top view of the schematic diagram of FIG. [Diagram 3] FIG. 2 is a schematic diagram of one embodiment in which a positive electrode and a negative electrode are in point contact with a laminate. [Figure 4] 4 is a photograph of the state of an aluminum thin film from which a positive electrode active material layer has been peeled off due to decomposition in Example 1 (top of FIG. 4), and a photograph of the state of the positive electrode active material that has been decomposed and turned into powder (bottom of FIG. 4). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Laminated Structure and Its Disassembly The laminate to be dismantled by the method according to the present invention basically comprises a thin film made of a conductor and a binder layer attached to the surface of the thin film. The two are bonded together by the presence of a specific substance. In one embodiment of the present invention, the binder layer is bonded to the thin film by a substance that acts as an adhesive, and the disassembly method according to the present invention is preferably applied to a laminate having such a configuration. In this embodiment, the adhesive is not limited to one that actively bonds the thin film and the binder layer, but may be a substance that is contained to bond the thin film and the binder layer and at the same time, to maintain the shape of the binder layer as a layer, for example, and may be present near the interface of the thin film of the binder layer as a substance that bonds the binder layer to the thin film.

[0011] According to the method of the present invention, the thin film and the binder layer of such a laminate can be separated while preventing mutual contamination at the interface between them. The effect of preventing mutual contamination between the materials constituting the thin film and the materials constituting the binder layer during this separation is extremely advantageous because it allows the material components of the thin film or the binder layer of the laminate to be efficiently recovered and reused. Both the thin film and the binder layer constituting the laminate separated by the method of the present invention may be subject to recovery. According to one embodiment, the adhesive is an organic substance.

[0012] The above-mentioned separation is possible in the present invention due to the following mechanism. That is, when a high voltage pulse is applied to the laminate, Joule heat is generated in the thin film. This Joule heat decomposes or melts the substance that exists near the interface between the adhesive layer and the thin film and binds them, such as the above-mentioned adhesive. As a result, the adhesive force between the thin film and the adhesive layer is loosened. Furthermore, the instantaneous and explosive physical force caused by the so-called pulse power caused by the application of the high voltage pulse cleanly peels off the thin film and the adhesive layer whose adhesive force has been loosened. It is considered that this allows the laminate to be dismantled without the material of the thin film and the material of the adhesive layer being mixed with each other. Here, the physical force caused by the pulse power means a composite force such as the sudden volume expansion of the high-temperature material caused by the plasma generated by the high voltage and the shock waves accompanying it.

[0013] In the present invention, the thin film constituting the laminate must be a conductor and must be thin enough to generate Joule heat required for dismantling the laminate by application of a high-voltage pulse. The specific thickness of the thin film depends on the conditions of the applied high-voltage pulse energy, the material (specific heat) of the thin film, and the area, and is preferably about 10 μm to 30 μm in thickness to raise the temperature to a level that deactivates the binding force of a typical laminate.

[0014] A specific example of a laminate to be dismantled by the method according to the present invention is a positive electrode or a negative electrode of a lithium ion battery.

[0015] According to one aspect of the present invention, the method according to the present invention is preferably applied to the positive electrode of a lithium ion battery. The positive electrode of a lithium ion battery is generally configured as a layer structure having a positive electrode active material layer on both sides of an aluminum thin film. The positive electrode active material layer contains a cobalt-based compound, specifically, lithium nickel oxide, lithium cobalt oxide, lithium manganate, lithium iron phosphate, and a ternary active material in which part of lithium cobalt oxide is replaced with nickel and manganese, and further contains carbon as a conductive assistant. Furthermore, the positive electrode active material layer contains these compounds in the form of a layer and a binder for binding to the aluminum thin film, and this binder is usually an organic substance, and polyvinylidene fluoride is often used.

[0016] In the method according to the present invention, when the positive electrode of the lithium ion battery is dismantled, the binder such as polyvinylidene fluoride is decomposed explosively by Joule heat, and the aluminum thin film and the positive electrode active material layer are separated at the interface without being mixed with each other. Here, according to a preferred embodiment of the present invention, the aluminum layer is separated while maintaining the shape of the thin film, that is, while maintaining the shape of the thin film, by appropriately controlling the applied high voltage pulse, and the mixing of small fragments of the aluminum layer into the positive electrode active material layer is suppressed. Since the positive electrode active material layer contains a binder not only at the interface with the aluminum layer but also inside the layer, the binder inside the layer is decomposed explosively by Joule heat, and the positive electrode active material layer does not maintain its shape as a layer but loses it, and is usually in the form of particles or powder. Then, useful metal resources such as cobalt can be efficiently recovered from the positive electrode active material obtained by dismantling.

[0017] Furthermore, the method according to the present invention can also be used to dismantle a laminate in which adhesive layers are provided on both sides of a thin film, such as the positive electrode of a lithium ion battery.

[0018] According to another aspect of the present invention, the negative electrode of a lithium ion battery can be dismantled in the same manner as the positive electrode. The negative electrode of a lithium ion battery is generally constructed as a layered structure having a layer in which an active material, a conductive additive carbon, and a binder such as styrene butadiene rubber are mixed on a thin copper film. As in the case of the positive electrode, when a high voltage pulse is applied to such a structure, the binder styrene butadiene rubber is explosively decomposed due to the instantaneous generation of Joule heat in the thin copper film, and the impact force such as the resulting shock wave can separate the layer of the active material from the thin copper film without mutual contamination.

[0019] Disassembly method The disassembly method according to the present invention comprises at least the following steps (a) to (c).

[0020] Process (a) This is a step of preparing a laminate comprising a thin conductive film and an adhesive layer bonded to the surface thereof, that is, a step of preparing the laminate already described.

[0021] The laminate to be disassembled in the present invention is usually a member constituting a part mounted on an apparatus, electronic device, etc. Therefore, it is necessary to carry out an operation to remove the laminate from the apparatus, device, or its part in advance to an extent that the electrodes can be contacted in the step (b) described later. The laminate thus obtained is subjected to the following step (b).

[0022] Process (b) This is a step of contacting a positive electrode and a negative electrode with the laminate prepared in step (a). In the present invention, the shape of the electrodes and the manner of contact are not particularly limited as long as a high voltage pulse can be applied to the laminate. According to a preferred embodiment of the present invention, at least one of the positive electrode and the negative electrode is point or a surface of the laminate, and more preferably both the positive electrode and the negative electrode are point In order to cause decomposition by pulsed power at a wide interface between the thin film and the binder layer in the laminate to be decomposed, point Alternatively, it may be advantageous to contact the laminate with the surface.

[0023] Fig. 1 is a schematic diagram of an embodiment in which a positive electrode and a negative electrode are in contact with a laminate. In the figure, a laminate 1 is composed of a thin film 11 and an adhesive layer 12 attached and supported on the front and back surfaces thereof. The ends of this laminate 1 are sandwiched between electrodes 20a, 20b, 21a, and 21b, and these electrodes are in contact with the laminate 1. Fig. 2 is a schematic top view of the state in which the electrodes sandwich and contact the laminate 1. In the embodiment of Figs. 1 and 2, both the positive electrode and the negative electrode are in contact with the laminate on their surfaces. These electrodes are connected to a high-voltage pulse generator 30 via high-voltage resistant cables 31 and 32.

[0024] Fig. 3 is a schematic diagram of an embodiment using electrodes that contact the laminate at points. In Fig. 3, electrodes 22 and 23 contact the laminate 1 at "points." In this figure, the laminate 1 is sandwiched and fixed by fixtures 40a, 40b, 41a, and 41b.

[0025] In the present invention, the electrodes may be in contact with the adhesive layer or directly with the thin film which is a conductor and generates Joule heat. Even if the adhesive layer is made of an insulator and the positive and negative electrodes are in physical contact with the adhesive layer but not in electrical contact with the thin film, a high voltage pulse can be applied by making it sufficient to cause dielectric breakdown of the adhesive layer and reach the thin film.

[0026] Process (c) This is a process in which a high voltage pulse is applied between the two electrodes in contact with the laminate. In the present invention, the high voltage pulse applied in this process is of a level that generates Joule heat in the thin film sufficient to decompose and melt the substance that binds the thin film and the binder layer and is present near the interface between the thin film and the binder layer. Furthermore, the thin film and the binder layer are separated by the pulse power generated by the application of the high voltage pulse, and the laminate is neatly dismantled while preventing the thin film and the binder layer from being mixed with each other.

[0027] The voltage and current of the high voltage pulse required to generate such Joule heat and pulse power may be determined taking into consideration the structure and materials of the laminate to be decomposed, particularly the type of organic matter and its melting point, etc., but in one embodiment of the present invention, to dismantle the positive electrode of a typical lithium ion battery, a voltage in the range of 4 kV to 30 kV and a current of 15 kA to 40 kA are applied as pulses depending on the capacitor capacity.

[0028] High-voltage pulse generators are known or well-known, and in the present invention, any device capable of generating the high-voltage pulse required to dismantle the laminated body may be used.

[0029] In the method according to the present invention, the application of the high voltage pulse may be carried out in air, or in water in order to effectively utilize the impulse force.

[0030] Recovery and reuse of useful substances and elements The recovery and reuse of useful substances and elements from the thin films and binder layers constituting the laminate may be carried out by a recovery and reuse method suitable for the materials and substances to be recovered.

[0031] According to the method of the present invention, when the positive electrode of a lithium ion battery is disassembled, the aluminum thin film constituting the thin film and the cobalt-based compound forming the positive electrode active material layer can be recovered while suppressing their mutual contamination. As a result, for example, when recovering cobalt, if the positive electrode is simply crushed and disassembled, the cobalt-based compound and small or fine pieces of aluminum must be separated, but in the method of the present invention, the aluminum thin film can be disassembled while maintaining the shape of the thin film, so that contamination of the cobalt-based compound is extremely small, and the efficiency of separation of cobalt is extremely high. EXAMPLES

[0032] The present invention will now be described in detail with reference to the following examples, but the present invention is not limited thereto.

[0033] Preparation of cathode material for lithium-ion batteries A cathode material sample was prepared as the laminate to be disassembled by cutting the cathode material of a lithium-ion battery for hybrid vehicles to a size of 30 mm x 80 mm. This cathode material had a structure in which a layer of cathode active material was provided on both sides of a thin aluminum film, the thin aluminum film was approximately 20 μm thick, and the thickness of the cathode active material layer on both sides was 30 μm.

[0034] Experimental example 1: Decomposition by surface contact electrodes In a manner similar to that shown in Fig. 1, the cathode material sample prepared above was sandwiched between electrodes connected to a high-voltage pulse generator, and a high-voltage pulse of 20 to 45 kv was applied to the electrodes. At 25 kV, the charging energy was 760 J. As a result, the aluminum thin film remained in almost the same thin film shape, while the cathode active material layer became powder, and the cathode sample was decomposed.

[0035] Experimental Example 2: Decomposition by Point Contact Electrodes In a manner similar to that shown in Fig. 3, the cathode material sample prepared above was sandwiched between electrodes connected to a high-voltage pulse generator, and a high-voltage pulse of 20 to 45 kV was applied to the electrodes. In this case, the charging energy was 1090 J. As a result, the aluminum thin film remained in almost the same thin film shape, while the cathode active material layer became powder, and the cathode sample was decomposed.

[0036] Recovery rate of cobalt from the recovered positive electrode active material layer and content of aluminum as an impurity The powders of the positive electrode active material layers obtained in Examples 1 and 2 were subjected to X-ray fluorescence analysis (XRF) to measure the contents (wt%) of cobalt, nickel, manganese, and aluminum. The results are shown in the following table. Table 1 shows the results for Example 1 at 25 kV and for Example 2 at 30 kV. The table also shows the contents of these elements in the entire positive electrode material before separation. [Table 1]

[0037] Furthermore, the recovery rate of cobalt (=weight of cobalt in peeled particles / weight of cobalt in the positive electrode active material layer before peeling) was calculated to be 94% in Example 1 and 84% in Example 2.

[0038] Aluminum thin film condition FIG. 4 shows a photograph (top of FIG. 4) of the aluminum thin film in Example 1 after the positive electrode active material layer has been peeled off by decomposition, and a photograph (bottom of FIG. 4) of the decomposed positive electrode active material in powder form. It can be seen from the photographs that the aluminum thin film is separated from the positive electrode active material without significant loss of its shape. The fact that the shape of the aluminum thin film is maintained means that there is little contamination of the separated positive electrode active material. Furthermore, such an aluminum thin film with a uniform shape is also advantageous for the recovery and reuse of aluminum. [Explanation of symbols]

[0039] 1...Laminate to be decomposed, 11...Thin film, 12...Binder layer, 20a, 20b, 21a, 21b...Electrodes in surface contact with the laminate, 22, 23...Electrodes in point contact with the laminate, 30...High voltage pulse generator, 31, 32...High voltage resistant cable, 40a, 40b, 41a, and 41b...Fixing device for the laminate

Claims

1. A method for dismantling a laminate, comprising the steps of: (a) preparing a laminate including a thin conductive film and an adhesive layer bonded to the surface of the thin conductive film; (b) contacting the laminate with a positive electrode and a negative electrode; and (c) applying a high voltage pulse between the electrodes; comprising wherein the high voltage pulse generates Joule heat in the thin film sufficient to decompose and melt a substance that binds the thin film and the binder layer and that is present in the vicinity of the interface between the thin film and the binder layer; and The method, characterized in that the thin film and the adhesive layer are separated by pulse power generated by application of the high voltage pulse, and the laminate is decomposed into the thin film and the adhesive layer.

2. The method of claim 1 , wherein the laminate is a positive electrode of a lithium ion battery.

3. 3. The method of claim 2, wherein the thin film is an aluminum thin film.

4. The method of claim 1 , wherein the laminate is a negative electrode of a lithium ion battery.

5. The method of claim 4 , wherein the thin film is a copper thin film.

6. The method according to any one of claims 1 to 5, wherein at least one of the positive electrode and the negative electrode contacts the laminate at a point or an area.

7. The method of claim 6 , wherein both the positive and negative electrodes contact the stack at a point or an area.

8. 8. The method of claim 1, wherein when the adhesive layer is made of an insulator and the positive electrode and / or the negative electrode are in physical contact with the adhesive layer and not in electrical contact with the thin film, the high voltage pulse is sufficient to cause an electrical breakdown of the adhesive layer and reach the thin film.

9. A method comprising a step of recovering useful substances or elements from the thin film and / or the adhesive layer obtained by dismantling the thin film and / or the adhesive layer obtained by the method according to any one of claims 1 to 8.

10. An apparatus for carrying out the method according to any one of claims 1 to 8, comprising: A positive electrode and a negative electrode are provided which are contactable with the laminate, The device further comprises an electric pulse unit that generates a high voltage pulse between the positive electrode and the negative electrode.

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