Pulse current generating device and pulse current generating method

Abstract

To separate a material of a laminate efficiently.SOLUTION: A pulse current generating device is connected to a thin film and separates the thin film and a binding layer bonded to the thin film by applying a pulse current to the thin film, and the pulse current generating device cuts the pulse current at a timing where a temperature of an adhesive that bonds the thin film and the binding layer reaches its melting point.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pulse current generating device and a pulse current generating method. [Background technology]

[0002] In order to efficiently recover resources, there is a need to recover useful substances from laminates such as lithium-ion batteries. A method of applying high voltage pulses is known as a method for separating materials from laminates (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-106024 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a current with damped oscillation is passed through the object, it may not be possible to efficiently separate the materials of the laminate. An object of the present invention is to provide a pulse current generating device and a pulse current generating method that efficiently separate materials in a laminate. [Means for solving the problem]

[0005] One aspect of the present invention is a pulse current generator that is connected to a thin film and separates the thin film from an adhesive layer adhered to the thin film by applying a pulse current to the thin film, and that cuts off the pulse current when the temperature of the adhesive that adheres the thin film to the adhesive layer reaches its melting point. [Effects of the Invention]

[0006] According to the present invention, the materials of the stack can be separated efficiently. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 10 is a diagram showing a pulse current generator connected to a laminate; [Figure 2] FIG. 2 is a schematic top view of a state in which electrodes sandwich and contact a laminate. [Figure 3] FIG. 10 is another diagram showing a pulse current generator connected to the stack. [Figure 4] FIG. 10 is a diagram illustrating an example of a simulation result of heat conduction. [Figure 5] FIG. 10 is a diagram showing a current passed through a thin film by a pulse current generator. [Figure 6A] FIG. 10 is a diagram showing experimental results. [Figure 6B] FIG. 10 is a diagram showing experimental results. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a pulse current generator 30 connected to a laminate. In FIG. 1, the laminate 1 is composed of a thin film 11, a binder layer 12, and an adhesive 13. The laminate 1 is, for example, the positive electrode of a lithium-ion battery. The thin film 11 is aluminum foil, the binder layer 12 is a positive electrode active material (PEAM), and the adhesive 13 is PVDF. The ends of the 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 top view schematic diagram showing the electrodes sandwiching and contacting the laminate 1. In FIGS. 1 and 2, both the positive and negative electrodes are in contact with the laminate 1 on their respective faces. These electrodes are connected to an output terminal 300 of the pulse current generator 30 via cables 31 and 32. The pulse current generator 30 outputs a pulse current from the output terminal 300, causing the pulse current to flow through the laminate 1. The circuit configuration of the pulse current generator 30 is not limited as long as it can output a desired pulse current.

[0009] FIG. 3 is another diagram showing a pulse current generator 30 connected to the laminate. In FIG. 3, electrodes 22 and 23 are in "point" contact with thin film 11. In FIG. 3, laminate 1 is sandwiched and fixed by fixtures 40a, 40b, 41a, and 41b. High-voltage pulse generator 30 applies a pulse current to thin film 11 by electrodes in contact with laminate 1 at the surface shown in FIG. 1 or at the point shown in FIG. 3. Electrodes 22 and 23 may be in contact with binder layer 12 to apply a current to binder layer 12.

[0010] When a pulse current flows through the thin film 11, the thin film 11 generates heat, and the heat is also conducted to the binder layer 12 and adhesive 13. The heat conduction from the thin film 11 to the binder layer 12 and adhesive 13 can be simulated by creating a heat conduction simulation model.

[0011] The following describes the formula for heat conduction when the thin film 11 is aluminum foil and the bonding layer 12 is PEAM. In the following equation, T' represents the temperature, T represents the temperature at the previous step, c represents the specific heat, m represents the mass, ρ represents the density, k represents the thermal conductivity, dt represents the time resolution, and dx represents the thickness resolution. T', T, c, m, ρ, and k are distinguished by subscripts. The subscript Al indicates that the parameter is for the aluminum foil. The subscript PE indicates that the parameter is for PEAM. The subscript PE indicates that the parameter is for PEAM. The subscript int indicates that the parameter is for the interface of the adhesive 13 of PEAM. The subscript mid indicates that the parameter is for the middle layer of PEAM. The subscript sur indicates that the parameter is for the surface of PEAM opposite the adhesive 13. The subscript Bou indicates that the parameter is for the adhesive 13.

[0012] Equation (1) is the temperature T' of the aluminum foil. Al Equation (2) shows the temperature rise dT of the aluminum foil caused by the application of a pulse current.Al This is the formula that shows R Al indicates the resistance of the aluminum foil. I indicates the magnitude of the pulse current flowing through the aluminum foil.

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[0013] Equation (3) is the temperature T' of the adhesive 13. Bou is the formula.

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[0014] Equation (4) is the temperature T' of the interface of the adhesive 13 of the PEAM. int is the formula.

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[0015] Equation (5) is the temperature T' of the intermediate layer of the PEAM. mid is the formula.

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[0016] Equation (6) is the temperature T' of the surface of the PEAM opposite to the adhesive 13. sur is the formula.

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[0017] Equations (1) through (6) can be used to simulate the temperatures of the film 11, tie layer 12, and adhesive 13.

[0018] The pulse current generator 30 cuts off the pulse current flowing through the thin film 11 at the timing when the temperature of the adhesive 13 reaches its melting point. The temperature of the adhesive 13 is calculated, for example, by simulation using equation (3), and the timing when the temperature of the adhesive 13 reaches its melting point can be obtained by simulation. By cutting off the pulse current flowing through the thin film 11 at the timing when the temperature of the adhesive 13 reaches its melting point, the pulse current generator 30 can prevent energy from being applied to the thin film 11 after that timing. In order to separate the thin film 11 and the binder layer 12, it is necessary to deactivate the adhesive 13 by raising the temperature of the adhesive 13 to a temperature equal to or higher than the melting point. However, if the temperature of the thin film 11 is increased, particles originating from the thin film 11 will be mixed as impurities into the binder layer 12, and therefore, it is desirable to keep the temperature of the thin film 11 low in order to separate the thin film 11 and the binder layer 12. Therefore, the pulse current generator 30 can deactivate the adhesive 13 while preventing particles originating from the thin film 11 from mixing into the binder layer 12 by cutting off the pulse current when the temperature of the adhesive 13 reaches the melting point.

[0019] Fig. 4 is a diagram showing an example of the results of a heat conduction simulation. The temperature of adhesive 13 rises and reaches its melting point at time T1. In the heat conduction simulation shown in Fig. 4, no pulse current is passed through thin film 11 after time T1.

[0020] 5 is a diagram showing the current that the pulse current generator 30 passes through the thin film 11. The pulse current generator 30 passes a pulse current through the thin film 11, but cuts off the pulse current at time T1 when the temperature of the adhesive 13 reaches its melting point. This allows the temperature change shown in FIG. 4 to occur in the adhesive 13 and the thin film 11.

[0021] 6A and 6B show experimental results. Fig. 6A shows the aluminum foil when the pulse current generator 30 cut off the pulse current when the temperature of the adhesive 13 reached its melting point. Fig. 6B shows the aluminum foil when the pulse current continued to flow even after the temperature of the adhesive 13 reached its melting point. The aluminum foil shown in FIG. 6A has a separated adhesive layer 12, but the aluminum foil shown in FIG. 6B contains a large amount of adhesive layer 12, making it difficult to separate.

[0022] Other Embodiments One embodiment of the present invention has been described in detail above with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes and the like are possible within the scope that does not deviate from the gist of the present invention. [Explanation of symbols]

[0023] 1 laminate to be decomposed, 11 thin film, 12 bonding layer, 13 adhesive, 20a, 20b, 21a, 21b electrodes in surface contact with the laminate, 22, 23 electrodes in point contact with the laminate, 30 pulse current generator, 300 output terminal, 301 current source, 302 switching element, 303 capacitor, 304 diode, 305 inductor, 31, 32 cable, 40a, 40b, 41a, 41b fixing device

Claims

1. A pulse current generator connected to a thin film, which applies a pulse current to the thin film to separate the thin film from an adhesive layer adhered to the thin film, The pulse current is interrupted when the temperature of the adhesive that bonds the thin film and the bonding layer reaches its melting point. Pulse current generator.

2. The timing at which the temperature of the adhesive reaches the melting point is calculated by simulating the heat conduction of the thin film, the bonding layer, and the adhesive.

2. The pulse current generator according to claim 1.

3. A pulse current generating method for separating a thin film from an adhesive layer adhered to the thin film by applying a pulse current to the thin film, comprising: The pulse current is interrupted when the temperature of the adhesive that bonds the thin film and the bonding layer reaches its melting point. Pulse current generation method.

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