Separation method, treatment method, electrode manufacturing method, separation device, and treatment device

Abstract

A separation method comprises: a hydrophilization step for subjecting an electrode being treated, which is provided with a current collector and an electrode mixture that is formed on the current collector, to a hydrophilization treatment; and an ultrasonic step for subjecting the electrode being treated, which was subjected to the hydrophilization treatment, to an ultrasonic treatment while sweeping the frequency of ultrasonic waves in treatment water, thereby separating the current collector and the electrode mixture. A treatment method comprises a plasma unit that performs a plasma treatment on an electrode mixture containing polyvinylidene fluoride so that the ratio of fluorine derived from the polyvinylidene fluoride, obtained through XPS analysis, satisfies at least one condition from among being reduced to 5 at% or less or being no more than 0.4 times the ratio before the plasma treatment.

Description

Separation method, processing method, electrode manufacturing method, separation apparatus and processing apparatus

[0001] This disclosure relates to a separation method, a processing method, a method for manufacturing electrodes, a separation apparatus, and a processing apparatus.

[0002] Conventionally, as a method for separating the current collector and electrode composite material during battery recycling, a method of ultrasonic treatment has been proposed in which ultrasonic waves are swept over the electrodes in water (for example, Patent Document 1). This method utilizes a physical action using the cavitation effect of ultrasound, rather than the chemical action of organic solvents or aqueous solutions. It is claimed that by using water and sweeping the ultrasonic frequency, the current collector and electrode composite material can be separated efficiently and with high precision. In addition, a method of pulverizing a mixture of particles consisting of lithium-ion battery positive electrode material by plasma treatment has been proposed (for example, Patent Document 2), and a method of removing polyvinylidene fluoride (PVdF) with O2 gas plasma has been proposed (for example, Non-Patent Document 1).

[0003] Japanese Patent Publication No. 2023-102744, International Publication No. 2022 / 109453A1, Pamphlet

[0004] ACS Appl. Mater. Interfaces 2024, 16, 24, 31076-31084

[0005] However, in the method described in Patent Document 1, the separation of the current collector and the electrode mixture can take a long time when processing electrodes with a thick electrode mixture layer or electrodes with high density, and there was a need for a more efficient method of separating the current collector and the electrode mixture. In addition, the methods in Patent Document 2 and Non-Patent Document 1 sometimes had low efficiency in decomposing and removing the binder.

[0006] This disclosure was made to solve these problems, and its main purpose is to more efficiently separate the current collector and the electrode composite material, or to efficiently disassemble and remove the binder.

[0007] To achieve the above-mentioned objectives, the inventors have discovered that by performing a hydrophilization treatment on an electrode to be treated, which comprises a current collector and an electrode mixture formed on the current collector, and then performing ultrasonic treatment while sweeping the ultrasonic frequency in the treated water, the current collector and the electrode mixture can be efficiently separated, thus completing this disclosure. Furthermore, they have discovered that by performing plasma treatment on an electrode mixture containing polyvinylidene fluoride as a binder under predetermined conditions, the polyvinylidene fluoride can be efficiently decomposed and removed.

[0008] That is, the separation method of the present disclosure includes a hydrophilization step of performing a hydrophilization treatment on an electrode to be treated, which comprises a current collector and an electrode mixture formed on the current collector, and an ultrasonic step of performing ultrasonic treatment on the electrode to be treated after the hydrophilization treatment while sweeping the frequency of ultrasonic waves in treated water to separate the current collector and the electrode mixture.

[0009] Furthermore, the processing method of the present disclosure includes a plasma step of performing plasma treatment on an electrode mixture containing polyvinylidene fluoride so that one or more of the following conditions (7) and (8) are met: (7) The proportion of fluorine derived from polyvinylidene fluoride as determined by XPS analysis is reduced to 5 at% or less. (8) The proportion of fluorine derived from polyvinylidene fluoride as determined by XPS analysis is 0.4 times or less than that before the plasma treatment.

[0010] Furthermore, the electrode manufacturing method of this disclosure includes an electrode manufacturing step of manufacturing a new electrode using at least one of the electrode composite material and the current collector obtained by the separation method described above.

[0011] Alternatively, the electrode manufacturing method of the present disclosure includes an electrode manufacturing step of manufacturing a new electrode using the electrode composite material processed by the processing method described above.

[0012] Furthermore, the separation device of this disclosure comprises: a hydrophilization unit that performs hydrophilization treatment on an electrode to be treated, which comprises a current collector and an electrode mixture formed on the current collector; an ultrasonic unit that performs ultrasonic treatment on the electrode to be treated after the hydrophilization treatment in treated water to separate the current collector and the electrode mixture; and a control unit that controls the ultrasonic unit to perform the ultrasonic treatment while sweeping the frequency of the ultrasonic waves.

[0013] Furthermore, the apparatus of this disclosure includes a plasma section that performs plasma treatment on an electrode mixture containing polyvinylidene fluoride so that one or more of the following conditions (7) and (8) are met: (7) The proportion of fluorine derived from polyvinylidene fluoride, as determined by XPS analysis, is reduced to 5 at% or less. (8) The proportion of fluorine derived from polyvinylidene fluoride, as determined by XPS analysis, is 0.4 times or less than that before the plasma treatment.

[0014] The separation method and apparatus of this disclosure can separate the current collector and the electrode mixture more efficiently. Furthermore, the electrode manufacturing method of this disclosure, which uses at least one of the electrode mixture and current collector obtained by this separation method to produce a new electrode, can efficiently produce a new electrode from the electrode to be processed. The reason for these effects is presumed to be, for example, as follows: In this separation method, separation apparatus and electrode manufacturing method, a hydrophilization treatment is performed prior to ultrasonic treatment in the treated water. This increases the hydrophilicity of the electrode mixture, making it easier for the treated water to permeate, and it is presumed that the cavitation effect is suitably expressed in the electrode during ultrasonic treatment, allowing for more efficient separation of the current collector and the electrode mixture. Furthermore, the processing method and apparatus of this disclosure can efficiently decompose and remove the binder contained in the electrode mixture, and the electrode manufacturing method of this disclosure, which uses the electrode mixture processed by this method to produce a new electrode, can efficiently produce a new electrode.

[0015] Diagrams illustrating the sweep and sweep cycle. Diagram illustrating the sweep width. Diagram illustrating the general configuration of the separation device 10. Diagram illustrating the general configuration of the plasma section 20, which is an example of a hydrophilic section. Diagram illustrating the general configuration of the ultrasonic section 30. Flowcharts illustrating the procedures for experimental examples 1 to 55. Graphs showing the relationship between plasma treatment time and asphalt detachment rate for experimental examples 56 to 61. XPS analysis results for experimental examples 56 to 59. XPS analysis results for experimental examples 56, 58, 60 to 61. TOF-SIMS analysis results for experimental examples 56 to 59. TOF-SIMS analysis results for experimental examples 56, 58, 60 to 61. Graphs showing the relationship between plasma treatment time and asphalt detachment rate.

[0016] 1. First Embodiment [Separation Method] The separation method of the present disclosure includes a hydrophilization step of performing a hydrophilization treatment on the electrode to be treated, and an ultrasonic step of performing ultrasonic treatment on the electrode to be treated after the hydrophilization treatment in treated water to separate the current collector and the electrode composite material.

[0017] (Electrode to be processed) The electrode to be processed comprises a current collector and an electrode composite formed on the current collector. The electrode to be processed is an electrode in an ion secondary battery such as a lithium-ion secondary battery, or in an energy storage device such as an electric double-layer capacitor, hybrid capacitor, or pseudo-electric double-layer capacitor, and may be taken from a used or degraded energy storage device. The electrode to be processed may be a positive electrode, a negative electrode, or a bipolar electrode in which a positive electrode composite is formed on one side and a negative electrode composite is formed on the other side. The electrode to be processed may be one that has been taken from an energy storage device and has not been shredded, for example, with an area of ​​3 cm². 2 More than 5 cm 2 , 10cm 2 The above may also be used.

[0018] Examples of the material of the current collector include aluminum, copper, titanium, stainless steel, nickel, iron, fired carbon, conductive polymer, conductive glass, etc. Among these, when the electrode to be processed is a positive electrode, it is preferable that the current collector contains aluminum. Examples of the shape of the current collector include foil shape, film shape, sheet shape, net shape, punched or expanded shape, lath body, porous body, foam body, formed body of fiber group, etc. The thickness of the current collector is, for example, 1 to 500 μm.

[0019] The electrode mixture may include an electrode active material, a binder, and a conductive material, etc. as needed. For example, the electrode mixture may be formed by mixing an electrode active material, a conductive material, and a binder, adding an appropriate solvent to make it into a paste shape, applying and drying it on the surface of the current collector, and compressing it as needed to increase the electrode density. The electrode mixture may be formed on one side or both sides of the current collector.

[0020] Examples of the electrode active material included in the electrode mixture include transition metal sulfides such as TiS2, TiS3, MoS3, FeS2, etc., lithium manganese composite oxides with the basic composition formula of Li (1-x) MnO2 (0 < x < 1, etc., the same below) and Li (1-x) Mn2O4, etc., lithium cobalt composite oxides with the basic composition formula of Li (1-x) CoO2, etc., lithium nickel composite oxides with the basic composition formula of Li (1-x) NiO2, etc., lithium nickel cobalt manganese composite oxides with the basic composition formula of Li (1-x) Ni a Co b Mn cExamples of active materials used in the positive electrode of lithium-ion secondary batteries include lithium nickel cobalt manganese composite oxide with a basic composition formula such as O2 (a + b + c = 1), lithium vanadium composite oxide with a basic composition formula such as LiV2O3, transition metal oxides with a basic composition formula such as V2O5, and lithium iron phosphate. The electrode active material may also include layered rock salt type active materials such as lithium nickel cobalt manganese composite oxide. Note that "basic composition formula" means that other elements such as Al and Mg may also be included. Examples of electrode active materials include activated carbon, coke, glassy carbon, graphite, non-graphitizable carbon, pyrolytic carbon, carbon fibers, carbon nanotubes, and polyacenes, which are used in the positive and / or negative electrodes of capacitors and lithium-ion capacitors. Furthermore, examples of electrode active materials include inorganic compounds such as lithium alloys and tin compounds, carbonaceous materials capable of intercalating and releasing lithium ions, composite oxides containing multiple elements, and conductive polymers, which are used as active materials for the negative electrode of lithium-ion secondary batteries. Examples of carbonaceous materials include cokes, glassy carbons, graphites, non-graphitizable carbons, pyrolytic carbons, and carbon fibers. Examples of composite oxides include lithium titanium composite oxide and lithium vanadium composite oxide. Examples of conductive materials included in electrode composites include graphite such as natural graphite (scaly graphite, flake graphite) and artificial graphite, acetylene black, carbon black, Ketjenblack, carbon whiskers, needle coke, carbon fibers, and metals (copper, nickel, aluminum, silver, gold, etc.).

[0021] The binder included in the electrode mixture plays the role of binding the active material particles and conductive material particles together. It may be a solvent-based binder used by dissolving it in an organic solvent, a water-based binder used by dissolving it in water or various aqueous solutions, or a mixture thereof. Examples of solvent-based binders include fluororesins such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), and fluororubber, or thermoplastic resins such as polypropylene and polyethylene, ethylene propylene diene monomer (EPDM) rubber, sulfonated EPDM rubber, and natural butyl rubber (NBR). The solvent-based binder may be a hydrophobic binder. Examples of water-based binders include polyvinyl alcohol (PVA), styrene-butadiene copolymer (SBR), and polyethylene oxide (PEO), and may also contain carboxymethylcellulose (CMC). The water-based binder may be a hydrophilic binder. Examples of organic solvents include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, N,N-dimethylaminopropylamine, ethylene oxide, and tetrahydrofuran. The binder is preferably a solvent-based binder. Solvent-based binders are generally hydrophobic, which suppresses the penetration of treated water into the electrode mixture and contributes to the time required for separation of the current collector and the electrode mixture. Therefore, applying this disclosure is particularly meaningful when the binder is a solvent-based binder. The conductive material included in the electrode mixture can be, for example, a mixture of one or more of the following: graphite such as natural graphite (scaly graphite, flake graphite) or artificial graphite, acetylene black, carbon black, Ketjenblack, carbon whiskers, needle coke, carbon fiber, or metals (copper, nickel, aluminum, silver, gold, etc.). Among these, carbon black and acetylene black are preferred as conductive materials from the viewpoint of electronic conductivity and coating properties.

[0022] The basis weight of the electrode composite layer is, for example, 5 mg / cm². 2 The above is also acceptable: 10 mg / cm³ 2 The above is also acceptable: 20 mg / cm³ 2The above may be adopted. Also, the thickness of the electrode mixture layer may be, for example, 20 μm or more, 40 μm or more, or 60 μm or more. Further, the density of the electrode mixture layer may be, for example, 2 g / cm 3 or more, 2.5 g / cm 3 or more, 3 g / cm 3 or more. When the basis weight of the electrode mixture layer is large, the thickness is large, the density is high, etc., the treated water is less likely to penetrate into the electrode mixture layer, and it tends to take time to separate the current collector and the electrode mixture. Therefore, the significance of applying the present disclosure is high.

[0023] (Hydrophilic treatment step) In the hydrophilic treatment step, a hydrophilic treatment is performed on the target electrode to be treated. The hydrophilic treatment is a treatment for enhancing the hydrophilicity of the electrode mixture. The hydrophilic treatment may be a treatment for reducing the contact angle between the surface of the electrode mixture and the treated water described later. From the viewpoint of improving the mixture peeling rate, the smaller the contact angle is, the better. For example, 100° or less is preferable, 50° or less is more preferable, and 10° or less is even more preferable. The hydrophilic treatment is not particularly limited as long as it can enhance the hydrophilicity of the electrode mixture. For example, it may be a plasma treatment using plasma.

[0024] The plasma treatment is preferably a low-temperature plasma treatment. Low-temperature plasma is a non-equilibrium (non-thermal equilibrium) plasma in which the electron temperature is higher than the gas temperature. The plasma temperature may be, for example, 200°C or less, or 100°C or less. The plasma temperature may be, for example, 0°C or more, or 20°C or more. Examples of the gas (reaction gas or purge gas) used for the plasma treatment include those containing one or more of oxygen (O2), nitrogen (N₂), and argon (Ar). Those containing oxygen (oxygen-containing gas) are preferable, and air may also be used. The flow rate of the gas used for the plasma treatment is based on the surface area of the electrode mixture layer of 10 cm 2It may be 1 mL / min or more, 2 mL / min or more, 5 mL / min or more, or it may be 50 mL / min or less, 20 mL / min or less, 15 mL / min or less. The plasma treatment may be carried out under reduced pressure (or vacuum) or under atmospheric pressure. From the viewpoint of improving the composite material peeling rate, reduced pressure (or vacuum) is preferable, and from the viewpoint of improving workability, such as when processing a large amount, atmospheric pressure is preferable. The reduced pressure (or vacuum) may be, for example, 150 Pa or less, 100 Pa or less, or 50 Pa or less. The plasma treatment may be, for example, high-frequency plasma treatment using high-frequency discharge of 1 MHz or more and 1 GHz or less. Among these, it may be capacitively coupled plasma treatment (parallel plate type) or inductively coupled plasma treatment (coil type). From the viewpoint of improving the composite material peeling rate, a larger high-frequency output is preferable. For example, per 10 cm 2 of the surface area of the electrode composite material layer (or per 200 mg of the electrode composite material), 50 W or more is preferable, 100 W or more is more preferable, and 150 W or more is even more preferable. The high-frequency output may be, for example, 300 W or less, per surface area of 2 the electrode composite material layer of 10 cm (or per 200 mg of the electrode composite material), 250 W or less, or 200 W or less. The plasma treatment may be one using, for example, corona discharge, dielectric barrier discharge, microwave discharge, etc.

[0025] From the viewpoint of shortening the plasma treatment time, it is preferable to carry out the plasma treatment in a short time, preferably 3 minutes or less, more preferably 2 minutes or less, and it may be 1 minute or less. From the viewpoint of improving the composite material peeling rate, a longer time is preferable, preferably 2 seconds or more, more preferably 5 seconds or more, and even more preferably 10 seconds or more.In the case of performing plasma treatment using an oxygen-containing gas, if the plasma treatment is carried out for, for example, 30 seconds or more or 60 seconds or more, the composite material peeling rate increases more preferably. On the other hand, in the case of performing plasma treatment using argon gas or nitrogen gas, if the plasma treatment is carried out in the range of, for example, less than 60 seconds or 45 seconds or less, the composite material peeling rate increases more preferably.

[0026] Plasma treatment is preferably performed under conditions where the contact angle between the electrode mixture surface and the treated water (described later) is 10° or less. A contact angle of 8° or less or 6° or less is more preferable. As the contact angle tends to decrease with longer plasma treatment times, from the viewpoint of shortening the plasma treatment time, a contact angle of 2° or more is preferable, 3° or more is more preferable, and 4° or more is even preferable.

[0027] (Ultrasonic Process) In the ultrasonic process, the electrode to be treated after hydrophilization is subjected to ultrasonic treatment while immersed in the treatment water (while the electrode is submerged in the treatment water), by sweeping the ultrasonic frequency. Sweeping the frequency means periodically changing the frequency, for example, as shown in Figures 1 and 2. The ultrasonic treatment may be performed using an ultrasonic probe, but it is preferable to perform it in an ultrasonic bath.

[0028] In ultrasonic treatment, the ultrasonic frequency may be periodically changed so as to oscillate between the maximum frequency Fmax and the minimum frequency Fmin, centered around the fundamental frequency F0 (see Figures 1 and 2). From the viewpoint of suppressing damage to the current collector, a higher fundamental frequency F0 is preferable, for example, 40 kHz or higher is preferable, and 80 kHz or higher is more preferable. From the viewpoint of improving the asphalt peeling rate, a lower fundamental frequency F0 is preferable, for example, 240 kHz or lower is preferable, and 200 kHz or lower is more preferable. In ultrasonic treatment, when the range of frequency fluctuation centered on the fundamental frequency F0 is defined as the sweep range (see Figure 2), the sweep range may be within ±5 kHz. That is, Fmax - F0 ≤ +5 kHz and Fmin - F0 ≥ -5 kHz. The sweep range may be within ±3 kHz or within ±1 kHz. In ultrasonic processing, one sweep cycle is defined as the period from the rising edge of the wave with the minimum frequency Fmin to the falling edge of the wave with the maximum frequency Fmax (see Figure 1). When the number of sweep cycles per second is defined as the sweep rate, the sweep rate may be 500 sweep cycles / second or more. The sweep rate may also be 700 sweep cycles / second or more, or 1000 sweep cycles / second or more. Furthermore, the sweep rate may be 2000 sweep cycles / second or less. Note that one sweep cycle may be half the period from the rising edge of the wave with the minimum frequency Fmin to the rising edge of the next wave with the minimum frequency Fmin.

[0029] From the viewpoint of reducing the ultrasonic treatment time, a shorter duration is preferable. For example, it is preferable to perform the ultrasonic treatment within a range of 60 minutes or less, more preferably within a range of 30 minutes or less, even more preferably within a range of 10 minutes or less, and even more preferably within a range of 5 minutes or less. From the viewpoint of improving the asphalt detachment rate, a longer duration is preferable. For example, it may be performed for 1 second or more, 30 seconds or more, or 1 minute or more.

[0030] Ultrasonic treatment reduces the contact area between the current collector and the electrode composite material by A [cm²]. 2 When the ultrasonic output (oscillator output) is B [W], the power density (power density) expressed as B / A is 150 W / cm².2 It is preferable to perform ultrasonic treatment as follows: The power density B / A is 50 W / cm². 2 The following is also acceptable: 30 W / cm² 2 The following is also acceptable: Power density B / A is 10 W / cm². 2 The above is also acceptable, at 50W / cm². 2 You may leave it at that.

[0031] Ultrasonic treatment is preferably performed in a non-heated environment. For example, ultrasonic treatment may be performed within a temperature range of 0°C to 30°C, or within a temperature range of 15°C to 25°C.

[0032] The treated water may be water, or an aqueous solution obtained by dissolving a solute such as an acid or base in water. The water may be tap water, distilled water, or deionized water. The aqueous solution may be an acid solution or a buffer solution. Because the treated water contains water, it easily permeates the electrode composite layer which has been made hydrophilic by the hydrophilization treatment, allowing the ultrasonic cavitation effect to be efficiently realized. Furthermore, since the treated water does not require organic solvents, it is preferable from the viewpoint of reducing environmental impact.

[0033] In the separation method described above, the electrode mixture is removed from the current collector, and the electrode mixture removed from the current collector is dissolved and / or dispersed in the treated water, or precipitated. Thus, after ultrasonic treatment, the current collector and the electrode mixture are separated, and the current collector and treated water containing the electrode mixture are obtained. The treated water containing the electrode mixture may be separated into a solid phase containing the electrode mixture and a liquid phase by solid-liquid separation methods such as filtration or centrifugation.

[0034] The electrode material removal rate (peeling rate) obtained by removing the electrode material from the current collector using this separation method is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more.

[0035] This separation method may be carried out in a batch or continuous manner. When this separation method is carried out continuously, a roll-to-roll method may be used. Furthermore, since current collectors and electrode mixtures are obtained by this separation method, this separation method is also a method for manufacturing current collectors and electrode mixtures.

[0036] Before the hydrophilization process, an extraction process may be performed to remove the electrodes from the energy storage device. The electrodes removed in the extraction process can be used as is, or in a 1 cm² area, without being shredded. 2 The electrodes may be cut into the above shapes and used as the electrodes to be processed. Alternatively, a removal treatment may be performed before the hydrophilization process to remove organic solvents contained in the electrodes (for example, organic solvents originating from the electrolyte of the energy storage device). This removal treatment may be performed by heating in an inert atmosphere.

[0037] [Separation device] The separation device of this disclosure comprises a hydrophilization unit that performs hydrophilization treatment on the electrode to be treated, an ultrasonic unit that performs ultrasonic treatment on the electrode to be treated after hydrophilization treatment in treated water to separate the current collector and the electrode mixture, and a control unit that controls the ultrasonic unit. This separation device may perform the separation method described above, or it may apply the configuration and conditions described in the separation method described above.

[0038] Hereinafter, a separation device 10 will be described as an example of the separation device of this disclosure. The separation device 10 performs plasma treatment as a hydrophilization treatment. Figure 3 shows an explanatory diagram illustrating the general configuration of the separation device 10. As shown in Figure 3, the separation device 10 comprises a plasma section 20 as a hydrophilization section, an ultrasonic section 30, and a control unit 15 that controls the entire separation device 10. Figure 4 shows an explanatory diagram illustrating the general configuration of the plasma section 20. Figure 5 shows an explanatory diagram illustrating the general configuration of the ultrasonic section 30. Figure 5A is an explanatory diagram illustrating the general configuration of the ultrasonic section 30 before ultrasonic treatment. Figure 5B is an explanatory diagram illustrating the general configuration of the ultrasonic section 30 after ultrasonic treatment. In this separation device 10, a target electrode 50 comprising a current collector 52 and an electrode mixture 54 is treated to separate the current collector 52 and the electrode mixture 54. The target electrode 50, the current collector 52, and the electrode mixture 54 may be the same as the target electrode, current collector, and electrode mixture described in the separation method described above.

[0039] The plasma unit 20 is configured as a plasma processing apparatus that performs plasma processing on the electrode mixture 54 of the electrode 50 to be processed. As shown in Figure 4, the plasma unit 20 comprises a chamber 22 and a pair of flat plate electrodes 24a and 24b arranged parallel to each other and spaced apart within the chamber. The chamber 22 is provided with gas piping (not shown) that allows for depressurization of the chamber and introduction and discharge of gas into and out of the chamber. One of the flat plate electrodes 24a is grounded. The other flat plate electrode 24b is connected to a high-frequency power supply 28 via a capacitor 26. The electrode 50 to be processed is positioned on this flat plate electrode 24b such that the electrode mixture 54 faces the flat plate electrode 24a. The plasma unit 20 is configured such that when the chamber 22 is in a predetermined depressurized atmosphere and high frequency is applied from the high-frequency power supply 28, plasma is generated between the flat plate electrodes 24a and 24b, and this plasma makes the electrode mixture 54 of the electrode 50 to be processed hydrophilic. As a result, the electrode 50 to be processed becomes the electrode 50A (Figure 5) equipped with the electrode composite material 54A after plasma treatment. In this example, the plasma unit 20 is a capacitively coupled plasma apparatus using parallel plate electrodes, but the plasma unit 20 may also use corona discharge, dielectric barrier discharge, microwave discharge, etc.

[0040] The ultrasonic unit 30 is configured as an ultrasonic treatment apparatus that performs ultrasonic treatment on the electrode 50A to be treated after plasma treatment in treated water 42. As shown in Figure 5, the ultrasonic unit 30 comprises a treatment container 32, a transducer 38, and an oscillator 40. The treatment container 32 contains the electrode 50A to be treated and the treated water 42. The treatment container 32 comprises an inner tank 34 in which the electrode 50A to be treated is housed, a mounting base 35 on which the inner tank 34 is placed, and an outer tank 36 in which the inner tank 34 and the mounting base 35 are housed. The inner tank 34 contains the treated water 42, and the outer tank 36 contains an ultrasonic propagation medium 46. For example, water is used as the treated water 42. The treated water 42 may be tap water, distilled water, or ion-exchanged water. The ultrasonic propagation medium 46 is, for example, water, and plays the role of propagating ultrasound together with the treated water 42. The processing container 32 is equipped with piping and valves (not shown) that allow for adjustment of whether or not treated water 42 is supplied to the processing container 32 and the amount supplied. The transducer 38 is positioned to be in contact with the processing container 32. The oscillator 40 supplies power to the transducer 38 and causes it to oscillate. The oscillator 40 has a sweep function. The sweep function is a function that periodically changes the frequency, for example, as shown in Figures 1 and 2. The ultrasonic unit 30 is configured to sweep (periodically change) the frequency of the ultrasonic waves generated from the transducer 38 by using the sweep function of the oscillator 40.

[0041] The control unit 15 is configured as a microprocessor centered on a CPU, and in addition to the CPU, it is equipped with a memory device and input / output ports (not shown). The control unit 15 is electrically connected to the high-frequency power supply 28 of the plasma unit 20 and the oscillator 40 of the ultrasonic unit 30, and outputs a signal to one of them and receives a signal from one of them. The control unit 15 is configured to control the high-frequency power supply 28 of the plasma unit 20 so that it outputs a high frequency under predetermined conditions (frequency, output, processing time, etc.). The control unit 15 is also connected to valves and pumps provided in the piping of the chamber 22 (not shown), and is configured to control the chamber 22 so that it satisfies predetermined conditions (pressure, gas type, gas flow rate, etc.). The conditions for plasma processing may be the same as those for the separation method described above. The control unit 15 is also configured to control the oscillator 40 of the ultrasonic unit 30 so that ultrasonic processing is performed while sweeping the ultrasonic frequency. The conditions for ultrasonic processing may be the same as those for the separation method described above.

[0042] An example of the operation of the separation device 10 will be described. First, the control unit 15 controls valves, pumps, etc., provided in the piping of the chamber 22 to create a predetermined reduced-pressure atmosphere inside the chamber. Next, the control unit 15 controls the high-frequency power supply 28 to output high frequency and generate plasma between the pair of flat plate electrodes 24a and 24b. It is believed that at least a portion of the electrode mixture 54 of the electrode to be processed 50 is plasma-treated by the plasma generated in this way, making it hydrophilic (increasing its hydrophilicity). As a result, the electrode to be processed 50 becomes the electrode to be processed 50A equipped with the electrode mixture 54A after plasma treatment.

[0043] Next, the treated water 42 is placed in the treatment container 32, and the electrode 50A to be treated after plasma treatment is immersed in the treated water 42. The treated water 42 can be any of the methods described above for separation. After the electrode 50A to be treated is immersed in the treated water 42, the control unit 15 controls the oscillator 40 to supply power to the transducer 38, causing the transducer 38 to oscillate. This performs ultrasonic treatment on the electrode 50A in the treated water 42. For ultrasonic treatment, the control unit 15 uses the sweep function of the oscillator 40 to control the oscillator 40 so that the frequency is swept under conditions such as a fundamental frequency F0 of 80 kHz or more and 200 kHz or less, a sweep width of ±3 kHz or less, and a sweep rate of 500 sweep cycles / second or more. The control unit 15 also controls the output density B / A to be 150 W / cm², for example. 2 The oscillator 40 is controlled to output the following power. The control unit 15 also controls the oscillator 40 to perform ultrasonic treatment for a predetermined time, for example, within a range of 10 minutes or less. Through this ultrasonic treatment, the current collector 52 and the electrode mixture 54A of the electrode 50A to be treated are separated, and treated water 43 containing the mixture, which includes the current collector 52 and the electrode mixture 54A, is obtained.

[0044] The separation method and apparatus described above can separate the current collector and the electrode mixture more efficiently. The reason for this effect is presumed to be, for example, as follows: In this separation method and apparatus, ultrasonic treatment is performed in the treated water. At that time, since the ultrasonic treatment is performed while sweeping the ultrasonic frequency, the energy distribution becomes favorable, and the current collector and the electrode mixture can be efficiently separated. In addition, prior to the ultrasonic treatment in the treated water, a hydrophilization treatment such as plasma treatment is performed on the electrode to be treated. This increases the hydrophilicity of the electrode mixture, making it easier for the treated water to permeate, and it is presumed that the cavitation effect is favorably expressed in the electrode during ultrasonic treatment, allowing for more efficient separation of the current collector and the electrode mixture. As a result, for example, even when using an electrode to be treated with a thick film such as an electrode mixture layer of 50 μm or more, the current collector and the electrode mixture can be efficiently separated without crushing the electrode or otherwise maintaining the electrode shape. Furthermore, the reason why plasma treatment makes the asphalt mixture hydrophilic is thought to be that electrons, ions, and radicals from the plasma generated by the plasma treatment collide with the surface of the asphalt mixture, react with the surface to form hydrophilic functional groups, activate the surface, and improve hydrophilicity. Alternatively, it is thought that the hydrophobic binder decomposes, improving hydrophilicity.

[0045] Furthermore, since electrode composites and current collectors can be obtained using the separation methods and apparatus described above, new electrodes can also be fabricated using at least one of these (electrode manufacturing method of this disclosure). The electrode composites and current collectors separated by the separation methods and apparatus described above may be used as is for the fabrication of electrodes, or the active material and conductive material may be separated from the electrode composite and used, or specific components may be separated from the active material and conductive material and used.

[0046] 2. Second Embodiment [Processing Method] The processing method of the present disclosure includes a plasma step of performing plasma processing on an electrode mixture containing polyvinylidene fluoride (PVdF). If the electrode mixture is formed on a current collector, this processing method may include a post-processing step of separating the current collector and the electrode mixture after the plasma step. Furthermore, this processing method may include a pre-processing step of recovering the electrode mixture in powder form prior to the plasma step.

[0047] (Electrode mixture) The electrode mixture may contain PVdF as a binder, and may be formed on the current collector, or it may be separated from the current collector beforehand. The electrode mixture and current collector may be those described in the first embodiment (provided that the binder is PVdF) as appropriate.

[0048] (Plasma Process) In the plasma process, the electrode mixture is subjected to plasma treatment so that the proportion of fluorine derived from PVdF, as determined by XPS (X-ray Photoelectron Spectroscopy) analysis, is reduced to 5 at% or less, or to 0.4 times or less than the amount before plasma treatment, satisfying one or more of these conditions. In the plasma process, the conditions for plasma treatment of the first embodiment can be appropriately adopted without departing from this. The plasma process of the second embodiment may be performed as the hydrophilization treatment process of the first embodiment. Since a reduction in the proportion of fluorine derived from PVdF is considered to indicate the decomposition or disappearance of PVdF, it is preferable to perform plasma treatment so that the proportion of fluorine derived from PVdF becomes even smaller. This proportion of fluorine derived from PVdF may be 4 at% or less, 3 at% or less, 1 at% or more, or 1.5 at% or more. This proportion of fluorine derived from PVdF may be 0.3 times or less, 0.2 times or less than the amount before plasma treatment, or 0.1 times or more, or 0.12 times or more. In the plasma process, the plasma treatment may be performed so that the proportion of fluorine derived from LiF, as determined by XPS, in the electrode mixture satisfies one or more of the following conditions: 5 at% or more, or 5 times or more than before the plasma treatment. An increase in the proportion of fluorine derived from LiF is considered to indicate that LiF was formed as a decomposition product by the decomposition of PVdF, so it is preferable to perform the plasma treatment to increase the proportion of fluorine derived from LiF. This proportion of fluorine derived from LiF may be 15 at% or more, 17 at% or more, or 30 at% or less, or 25 at% or less. This proportion of fluorine derived from LiF may be 15 times or more, 17 times or more, or 30 times or less, or 25 times or less than before the plasma treatment. An increase in the proportion of fluorine derived from LiF is considered to indicate the decomposition or disappearance of PVdF. In the plasma process, the electrode mixture may be subjected to plasma treatment such that the proportion of oxygen derived from metal oxide MO (MO is an abbreviation for Metal Oxide), as determined by XPS, is 20 at% or less, or 25 times or less the proportion of fluorine derived from PVdF, or 2.5 times or less the proportion of fluorine derived from LiF.Since the generation of MO is thought to inhibit the delamination of the electrode mixture, it is preferable to perform plasma treatment in a way that minimizes the increase in MO. The proportion of oxygen derived from MO may be 10 at% or less, 7 at% or less, or 1 at% or more, or 2 at% or more. The proportion of oxygen derived from MO may be 5 times or less, 4 times or less, or 0.5 times or more, or 1 time or more, of the proportion of fluorine derived from PVdF. The proportion of oxygen derived from MO may be 0.5 times or less, 0.3 times or less, or 0.05 times or more, or 1.0 time or more, of the proportion of fluorine derived from LiF. The proportion of fluorine derived from PVdF and LiF can be determined using the F1s peak obtained by XPS analysis. The proportion of oxygen derived from MO can be determined using the O1s peak obtained by XPS analysis. Specifically, the proportions of PVdF, LiF, and MO obtained by XPS are determined as follows: First, a qualitative spectrum is obtained by XPS, and narrow spectra of all detected elements are obtained. The peak area of ​​each narrow spectrum is determined by subtracting the background, and after dividing by the relative sensitivity coefficient specific to the XPS instrument, the elemental composition ratio (including F and O) is calculated so that the sum of all elements is 100 at% (F: x / 100, O: y / 100). Next, the F1s narrow spectrum is waveform-separated into three components (l, m, n, l+m+n=1), and the proportion of LiF (l) and PVdF (n) in the total fluorine amount is determined. From these proportions and the total fluorine amount of the elemental composition ratio determined earlier, the amount of fluorine derived from LiF (x × l / 100 [at%]) and the amount of fluorine derived from PVdF (x × n / 100 [at%]) are calculated. In addition, the O1s narrow spectrum is waveform-separated into three components (a, b, c, a+b+c=1), and the proportion of MO in the total oxygen amount (a) is determined. From this ratio and the total amount of oxygen in the previously determined elemental composition ratio, the amount of oxygen originating from MO (y × a / 100 [at%]) is calculated.

[0049] In the plasma process, the electrode mixture is subjected to plasma treatment such that the peak intensities of the mass-to-charge ratio m / z 113 and 133 in the positive ion spectrum, as determined by TOF-SIMS (Time-of-Flight Secondary Ion Mass Spectrometry), become 1 / 100 or less of the pre-plasma treatment peak (including cases where the peak disappears). The 113 peak is C3HF4 + This indicates the presence of C3H2F5, and the 133 peaks are C3H2F5 + These peaks indicate the presence of PVdF, all of which originate from PVdF. The disappearance of these peaks suggests that PVdF has been decomposed or removed.

[0050] In the plasma process, when plasma treatment is performed on an electrode to be treated, in which the electrode composite material is formed on a current collector, it is preferable to perform the plasma treatment on the electrode to be treated so that the cutting strength of the electrode composite material, as determined by SAICAS (Surface And Interfacial Cutting Analysis System; SAICAS is a registered trademark of Daipla Wintes Co., Ltd.), is 70% or less (preferably 60% or less) of the strength before plasma treatment. A decrease in cutting strength is thought to indicate the decomposition or removal of PVdF. This cutting strength may be 10% or more of the strength before plasma treatment. In the plasma process, plasma treatment may be performed on the electrode to be treated so that the cutting strength of the electrode composite material, as determined by SAICAS analysis, is 0.2 kN / m or less (preferably 0.15 kN / m or less). This cutting strength may be 0.01 kN / m or more.

[0051] In the plasma process, it is preferable to perform oxygen plasma treatment on the electrode mixture for a period of 10 seconds to less than 180 seconds, and more preferably for a period of 30 seconds to 120 seconds. Plasma treatment conditions such as gas type, gas flow rate, high-frequency output, and treatment time can be appropriately determined based on quantitative indicators such as the results of the XPS analysis, TOF-SIMS analysis, and SAICAS analysis described above.

[0052] (Post-processing step) In the post-processing step, the electrode after the plasma process may be physically separated from the current collector and the electrode mixture by crushing, ultrasonic treatment, etc. The post-processing step may be performed without heating. For ultrasonic treatment, for example, the conditions for ultrasonic treatment described in the first embodiment can be appropriately adopted. The electrode mixture obtained in the post-processing step may be reused as a regenerated electrode.

[0053] (Pre-treatment process) In the pre-treatment process, the powdered electrode mixture to be used in the plasma process may be recovered by methods such as heating, mechanical crushing, and sorting. In this case, for example, the electrode mixture may be separated and recovered from the electrode on which the electrode mixture has been formed on the current collector. In the pre-treatment process, the positive electrode mixture may be recovered alone, or the negative electrode mixture may be recovered alone. In this case, after plasma treatment, the powdered electrode mixture may be used as is in the manufacture of regenerated electrodes. Alternatively, in the pre-treatment process, the electrode mixture may be recovered as a mixed powder of the positive electrode mixture and the negative electrode mixture. In this case, after plasma treatment, the positive electrode mixture and the negative electrode mixture may be separated by physical sorting using differences in particle specific gravity, hydrophilic / hydrophobicity, magnetic force, electrostatic force, etc.

[0054] [Processing Apparatus] The processing apparatus of the present disclosure includes a plasma section that performs plasma processing on an electrode mixture containing PVdF so that the proportion of fluorine derived from PVdF, as determined by XPS analysis, is reduced to 5 at% or less, or is 0.4 times or less than the amount before plasma processing, satisfying one or more of these conditions. This processing apparatus may perform the processing method described above, or it may apply the configuration and conditions described in the processing method described above. For example, plasma processing may be performed so that the values ​​obtained by XPS analysis, TOF-SIMS analysis, or SAICAS analysis fall within the numerical ranges described in the processing method described above. As this processing apparatus, for example, the separation apparatus 10 described in the first embodiment may be used. When the separation apparatus 10 is used as the processing apparatus of the second embodiment, the plasma section 20 only needs to be configured to perform plasma processing so that the proportion of fluorine derived from PVdF, as determined by XPS analysis, is reduced to 5 at% or less, or is 0.4 times or less than the amount before plasma processing, satisfying one or more of these conditions, and it is preferable that it is configured to perform plasma processing that matches the conditions described in the plasma process of the second embodiment. When the separation device 10 is used as the processing device of the second embodiment, the ultrasonic unit 30 and related components may be omitted.

[0055] The processing method and apparatus described above can efficiently decompose and remove binders contained in electrode composite materials. This processing method and apparatus can be applied to electrode plates in a plasma state, followed by ultrasonic treatment or crushing to improve separation from current collectors (such as aluminum foil). It can also be used in processing processes that apply plasma treatment to composite powder to remove binder components, and then perform physical sorting using differences in particle specific gravity, hydrophilic / hydrophobicity, magnetic force, and electrostatic force. This processing method and apparatus also has the advantage of being environmentally friendly because it can decompose and remove binders contained in electrode composite materials by low-temperature, dry plasma treatment.

[0056] Furthermore, the processing method and apparatus described above can efficiently decompose and remove the binder contained in the electrode mixture, and a new electrode can be made using it (electrode manufacturing method of this disclosure). In addition, it is possible to manufacture a high-purity active material by utilizing the effect of decomposing and removing the binder contained in the electrode mixture (method of manufacturing active material), and an electrode may be made using the obtained active material. In addition, it is possible to efficiently separate and recover the electrode mixture from the current collector by utilizing the effect of decomposing and removing the binder contained in the electrode mixture (method of manufacturing electrode mixture), and a new electrode may be made using the obtained electrode mixture. The electrode mixture processed by the processing method and apparatus described above may be used as is for the manufacture of electrodes, or the active material and conductive material may be separated from the electrode mixture and used, or specific components may be separated from the active material and conductive material and used.

[0057] It should be noted that this disclosure is not limited in any way to the first and second embodiments described above, and can be implemented in various forms as long as they fall within the technical scope of this disclosure.

[0058] For example, in the first and second embodiments described above, the separation device 10 performs plasma processing or ultrasonic processing in a batch manner, but it may also perform plasma processing or ultrasonic processing in a continuous manner.

[0059] This disclosure may be as shown in any of the following [1] to

[20] . [1] A separation method comprising: a hydrophilization step of performing a hydrophilization treatment on an electrode to be treated, which comprises a current collector and an electrode mixture formed on the current collector; and an ultrasonic step of performing ultrasonic treatment on the electrode to be treated after the hydrophilization treatment while sweeping the frequency of ultrasonic waves in treated water to separate the current collector and the electrode mixture. [2] The separation method according to [1], wherein the hydrophilization step is performed by plasma treatment. [3] The separation method according to [2], wherein the hydrophilization step is performed by using an oxygen-containing gas to perform the plasma treatment. [4] The separation method according to [2] or [3], wherein the hydrophilization step is performed under conditions that the contact angle between the surface of the electrode mixture and the treated water is 10° or less. [5] The separation method according to any one of [2] to [4], wherein the hydrophilization step is performed by performing the plasma treatment under conditions that satisfy one or more of the following (1) to (6). (1) The plasma treatment shall be performed within a range of 3 minutes or less. (2) The plasma treatment shall be performed in a gas containing one or more of oxygen, nitrogen, and argon. (3) The plasma treatment shall be performed on a surface area of ​​10 cm² of the electrode mixture. 2 (4) The plasma treatment is performed under a gas flow rate of 1 mL / min to 50 mL / min per unit area. (5) The plasma treatment is performed at a plasma temperature of 0°C to 200°C. 2The process is carried out at a power of 50W or more and 300W or less per unit. (6) The plasma treatment is carried out under reduced pressure or atmospheric pressure. [6] The separation method according to any one of [1] to [5], wherein the ultrasonic process is carried out by performing the sweep around a fundamental frequency of 80kHz or more and 200kHz or by performing the sweep with a sweep width of ±3kHz or less around the fundamental frequency. [7] The separation method according to any one of [1] to [6], wherein the ultrasonic process is carried out by performing the ultrasonic treatment for a period of 10 minutes or less. [8] The separation method according to any one of [1] to [7], wherein the electrode to be treated includes a solvent-based binder. [9] A processing method comprising a plasma process, wherein the electrode mixture containing polyvinylidene fluoride is subjected to plasma treatment so as to satisfy one or more of the following conditions (7) and (8). (7) The proportion of fluorine derived from polyvinylidene fluoride determined by XPS analysis is reduced to 5 at% or less. (8) The proportion of fluorine derived from polyvinylidene fluoride determined by XPS analysis is 0.4 times or less than that before the plasma treatment.

[10] The plasma treatment method according to [9], wherein the plasma treatment is performed on the electrode mixture so that one or more of the following conditions (9) and (10) are met. (9) The proportion of fluorine derived from LiF determined by XPS analysis is 15 at% or more. (10) The proportion of fluorine derived from LiF determined by XPS analysis is 15 times or more than that before the plasma treatment.

[11] The plasma treatment method according to [9] or

[10] , wherein the plasma treatment is performed on the electrode mixture so that one or more of the following conditions (11) to (13) are met. (11) The proportion of oxygen derived from metal oxide determined by XPS analysis is 10 at% or less. (12) The proportion of oxygen derived from metal oxide determined by XPS analysis is 5 times or less than the proportion of fluorine derived from polyvinylidene fluoride determined by XPS analysis. (13) The proportion of oxygen derived from metal oxides determined by XPS analysis is 0.5 times or less the proportion of fluorine derived from LiF determined by XPS analysis.

[12] The processing method according to any one of [9] to

[11] , wherein in the plasma step, the plasma treatment is performed on the electrode mixture such that the peak intensities of mass charge ratio m / z 113 and 133 in the positive ion spectrum obtained by TOF-SIMS analysis are each 1 / 100 or less of the peak intensities before the plasma treatment.

[13] The processing method according to any one of [9] to

[12] , wherein in the plasma step, oxygen plasma treatment is performed on the electrode mixture for a range of 10 seconds or more and less than 180 seconds.

[14] The processing method according to any one of [9] to

[13] , wherein the electrode mixture is formed on a current collector, and in the plasma step, the plasma treatment is performed such that the cutting strength of the electrode mixture by SAICAS is 70% or less of the peak intensities before the plasma treatment.

[15] The processing method according to any one of [9] to

[14] , wherein the electrode mixture is formed on a current collector, and includes a post-processing step of separating the current collector and the electrode mixture after the plasma step.

[16] A processing method according to any one of [9] to

[15] , comprising a pre-processing step of recovering the powdered electrode mixture prior to the plasma process.

[17] A method for manufacturing an electrode, comprising an electrode manufacturing step of manufacturing a new electrode using at least one of the electrode mixture and a current collector obtained by the separation method according to any one of [1] to [8].

[18] A method for manufacturing an electrode, comprising an electrode manufacturing step of manufacturing a new electrode using the electrode mixture processed by the processing method according to any one of [9] to

[16] .

[19] A separation device comprising: a hydrophilization unit that performs hydrophilization processing on an electrode to be processed, which comprises a current collector and an electrode mixture formed on the current collector; an ultrasonic unit that performs ultrasonic processing on the electrode to be processed after the hydrophilization processing in processing water to separate the current collector and the electrode mixture; and a control unit that controls the ultrasonic unit to perform the ultrasonic processing while sweeping the frequency of the ultrasonic waves.

[20] An apparatus comprising a plasma section that performs plasma treatment on an electrode mixture containing polyvinylidene fluoride so that one or more of the following conditions (7) and (8) are met. (7) The proportion of fluorine derived from polyvinylidene fluoride, as determined by XPS analysis, is reduced to 5 at% or less.(8) The proportion of fluorine derived from polyvinylidene fluoride, as determined by XPS analysis, is 0.4 times or less than that before the plasma treatment.

[0060] The following describes examples of implementing the separation method of this disclosure. Experimental Examples 2-7, 9-14, and 16-45 correspond to embodiments of the first embodiment, experimental Examples 1, 8, and 15 correspond to comparative examples, and experimental Examples 46-55 correspond to reference examples. Furthermore, experimental Examples 57-61 correspond to embodiments of the second embodiment, and experimental Example 56 corresponds to a comparative example.

[0061] Experimental examples 1 to 55 relating to the first embodiment were carried out according to the procedure shown in Figure 6.

[0062] 1. Preparation and Mass Measurement of Electrodes to be Treated The positive electrode was prepared according to the following procedure. The mass was measured for each electrode to be treated. LiNi was used as the positive electrode active material. 0.5 Co 0.2 Mn 0.3 A positive electrode composite material containing 95% by mass of O2 (NCM) (manufactured by Toda Kogyo), 3% by mass of acetylene black (manufactured by Denka) as a conductive material, and 2% by mass of polyvinylidene fluoride (PVdF) (manufactured by Kureha) as a binder was coated onto one side of a 20 μm thick aluminum current collector foil to form the positive electrode. The basis weight of the positive electrode composite layer was 20 mg / cm². 2 The thickness was 60 μm and the area was 20 mm x 50 mm.

[0063] 2. Plasma Treatment Low-temperature plasma treatment was performed on the electrodes to be treated using a Yamato Material plasma cleaner miniature plasma device PIPI. For the low-temperature plasma treatment, electrodes were placed in a chamber so that the electrode composite surface of the electrodes to be treated would be plasma-treated. After evacuating the chamber, a reaction gas was charged, the plasma mode was RIE (Reactive Ion Etching), the electrode-to-electrode distance was 80 mm, and a high-frequency voltage was applied between the parallel plate electrodes to generate plasma. The gas type, gas flow rate, high-frequency output, and treatment time were each one of the following: Gas: O2, N2, Ar (100% each) Gas flow rate: 10, 15 ml / min High-frequency output: 50, 100, 200 W Treatment time (holding time after reaching each output): 2 to 120 seconds (3 seconds to reach 200 W)

[0064] 3. Contact Angle Measurement The contact angle of the electrode composite surface was measured for the treated electrode after plasma treatment. The contact angle was measured using a Kyowa Interface Chemical automatic contact angle meter DM-501, with pure water, liquid volume: 1 μl, elapsed time: 1 second, temperature: 25°C, droplet method, θ / 2 method, at 5 points, and the average value was calculated.

[0065] 4. For the electrodes to be treated after ultrasonic treatment and plasma treatment, an ultrasonic device (Branson GCX-M-3FQ12, maximum output 500W, outer tank capacity 20L) was used. Water was placed in the washing tank (outer tank), 10 mL of water was placed in the glass container of the inner tank, and ultrasonic waves were applied from the transducer at the bottom of the outer tank. The electrodes to be treated were immersed in the device and ultrasonic treatment was performed at a temperature of 20°C while sweeping. The sweep conditions were the same for all tests: sweep width: ±1 kHz, sweep speed: 1000 sweep cycles / second. The ultrasonic frequency, treatment time, and output were one of the following: Frequency: 80, 120 kHz; Treatment time: 1 minute, 3 minutes; Output: 500W

[0066] 5. Mass Measurement and Asphalt Peeling Rate Measurement The mass of the treated electrode after ultrasonic treatment was measured. The asphalt peeling rate [%] was calculated by determining the amount of asphalt peeled off [mg] from the mass difference of the electrode before and after ultrasonic treatment, and the initial amount of asphalt [mg] from the basis weight and area of ​​the electrode asphalt layer in the initial electrode, and then using the following formula (1): Asphalt Peeling Rate = Amount of Asphalt Peeled / Initial Amount of Asphalt × 100 ...Formula (1)

[0067] [Experimental Example 1] No plasma treatment was performed, and ultrasonic treatment was performed at a frequency of 80 kHz, output of 500 W, and a processing time of 3 minutes. [Experimental Examples 2-7] For plasma treatment, gas was O2, gas flow rate was 10 ml / min, high-frequency output was 100 W, and time was 2-90 seconds. For ultrasonic treatment, frequency was 80 kHz, output of 500 W, and processing time was 3 minutes. [Experimental Example 8] No plasma treatment was performed, and ultrasonic treatment was performed at a frequency of 80 kHz, output of 500 W, and processing time was 1 minute. [Experimental Examples 9-14] For plasma treatment, gas was O2, gas flow rate was 15 ml / min, high-frequency output was 200 W, and time was 2-120 seconds. For ultrasonic treatment, frequency was 80 kHz, output of 500 W, and processing time was 1 minute. [Experimental Example 15] No plasma treatment was performed, and ultrasonic treatment was performed at a frequency of 120 kHz, output of 500 W, and processing time was 1 minute. [Experimental Examples 16-21] For plasma treatment, the gas was O2, the gas flow rate was 15 ml / min, the high-frequency output was 200 W, and the time was 2-120 seconds. For ultrasonic treatment, the frequency was 120 kHz, the output was 500 W, and the processing time was 1 minute. [Experimental Examples 22-27] For plasma treatment, the gas was N2, the gas flow rate was 15 ml / min, the high-frequency output was 200 W, and the time was 2-120 seconds. For ultrasonic treatment, the frequency was 80 kHz, the output was 500 W, and the processing time was 1 minute. [Experimental Examples 28-33] For plasma treatment, the gas was N2, the gas flow rate was 15 ml / min, the high-frequency output was 200 W, and the time was 2-120 seconds. For ultrasonic treatment, the frequency was 120 kHz, the output was 500 W, and the processing time was 1 minute. [Experimental Examples 34-39] For plasma treatment, the gas was Ar, the gas flow rate was 15 ml / min, the high-frequency output was 200 W, and the time was 2-120 seconds. For ultrasonic treatment, the frequency was 80 kHz, the output was 500 W, and the treatment time was 1 minute. [Experimental Examples 40-45] For plasma treatment, the gas was N2, the gas flow rate was 15 ml / min, the high-frequency output was 200 W, and the time was 2-120 seconds. For ultrasonic treatment, the frequency was 120 kHz, the output was 500 W, and the treatment time was 1 minute. [Experimental Examples 46-55] In Experimental Examples 46-55, ultrasonic treatment was not performed, and the differences in contact angle were confirmed by changing the conditions of the plasma treatment.

[0068] [Results and Discussion] Tables 1 and 2 summarize the plasma treatment conditions, contact angle, ultrasonic treatment conditions, and asphalt peeling rate for experimental examples 1 to 45. Table 3 summarizes the plasma treatment conditions and contact angle for experimental examples 46 to 55. Comparing the experimental examples where ultrasonic treatment was performed under the same conditions, the asphalt peeling rate was higher in the experimental examples where plasma treatment was performed than in the experimental examples where plasma treatment was not performed. In addition, the contact angle was smaller in the experimental examples where plasma treatment was performed than in the experimental examples where plasma treatment was not performed. From this, it was inferred that performing plasma treatment before ultrasonic treatment increased the hydrophilicity of the asphalt layer, thereby increasing the asphalt peeling rate.

[0069] In Experiments 2-21 using O2 gas for plasma treatment, the contact angle decreased more quickly in Experiments 9-14 and 16-21 (15 ml / min - 200 W) than in Experiments 2-7 (10 ml / min - 100 W). For example, in a plasma treatment of 10 ml / min - 100 W for 30 seconds, the asphalt detachment rate was 58.4% with ultrasonic treatment at 80 kHz for 3 minutes (Experiment 5), while in a plasma treatment of 15 ml / min - 200 W for 30 seconds, the asphalt detachment rate was 94.7% with ultrasonic treatment at 80 kHz for 1 minute (Experiment 12). The shorter the plasma treatment time, the greater the decrease in contact angle, and the faster the ultrasonic treatment time was needed to detach the asphalt. As shown in Table 3, it was confirmed that the contact angle decreases more quickly with higher flow rates and higher power outputs. From the perspective of improving the asphalt detachment effect, it was inferred that it is desirable to increase the hydrophilicity not only on the surface of the asphalt but also more deeply into its interior. It was hypothesized that the higher the gas flow rate, the higher the output, and the shorter the plasma treatment time, the lower the contact angle, which in turn increased the hydrophilicity of the asphalt mixture, even within the mixture. In all of the above 30-second plasma treatments, the contact angle was low, around 5°. However, for the reasons mentioned above, it was hypothesized that the hydrophilicity of the asphalt mixture was higher within the mixture when using 15 ml / min-200W than when using 10 ml / min-100W, resulting in a higher asphalt mixture peel rate. The time lag between the time the contact angle decreased to around 5° and the time the asphalt mixture peel rate increased was thought to be related to the depth of hydrophilization. In the 15 ml / min-200W plasma treatment with O2 gas, both the 80 kHz, 1 minute ultrasonic treatment and the 120 kHz, 1 minute ultrasonic treatment were highly effective in improving the asphalt mixture peel rate.

[0070] In experimental examples 22-33 using N2 gas for plasma treatment, and experimental examples 34-45 using Ar gas, the contact angle decreased to approximately 10° or less after 2 seconds of plasma treatment, similar to experimental examples 9-21 using O2 gas. However, when Ar gas was used, the effect of improving the asphalt detachment rate was small in both 80 kHz, 1 minute ultrasonic treatment and 120 kHz, 1 minute ultrasonic treatment. When N2 gas was used, the effect of improving the asphalt detachment rate was greater than when Ar gas was used, but it was inferior to when O2 gas was used. Since O2 showed the greatest effect in improving the asphalt detachment rate among the gas types, and N2 also showed a relatively high effect, it was inferred that even a mixed gas of O2 and N2 or air would have a relatively large effect in improving the asphalt detachment rate as a reaction gas.

[0071] With O2, N2, and Ar, a 10-second plasma treatment reduced the contact angle to approximately 5° or less (hydrophilization). However, the effectiveness in improving the asphalt detachment rate was highest with O2, followed by N2 and then Ar, with Ar showing the lowest improvement. The reason for this is discussed below. It was inferred that in the plasma treatment using O2 gas, hydrophilic oxidative functional groups were directly formed by a reaction with the asphalt surface. On the other hand, it was inferred that even in the case of plasma treatment using oxygen-free gases such as N2 and Ar, radicals were generated on the surface, and when the material was removed from the chamber, they reacted with oxygen molecules upon contact with air, forming oxidative functional groups on the surface. This was inferred from reference 1 (Fumio Ide, Journal of the Textile Machinery Society, Vol. 38, No. 4 (1985)), etc. From the above, it was inferred that when N2 or Ar gas was used, oxidative functional groups were formed only on the very surface of the electrode mixture layer, whereas when O2 gas was used, oxidative functional groups were formed deeper into the electrode mixture layer, resulting in sufficient hydrophilization of the mixture and a high effect in improving the mixture peel rate.

[0072] The contact angle is information about the outermost surface of the asphalt mixture. To enhance the effectiveness of improving the delamination rate of the asphalt mixture, it is desirable to hydrophilize not only the outermost surface of the electrode asphalt layer but also the interior. While a low contact angle alone can improve the delamination rate to some extent, it was inferred that to further enhance the delamination rate, it is desirable to hydrophilize the interior by increasing the plasma treatment time, increasing the output, or increasing the gas flow rate.

[0073] Plasmas are broadly classified into non-equilibrium plasmas (low-temperature plasmas) where the electron temperature is higher than the gas temperature, and plasmas in thermal equilibrium (thermal plasmas). Generally, low-temperature plasmas consist of highly reactive particles (electrons, ions, radicals, light) generated in a vacuum by ionization and dissociation resulting from collisions between high-speed electrons and gas. This point is shown in Reference 2 (Masaru Hori, Applied Physics, Vol. 89, No. 12 (2020)). In this experimental example, the electrode to be treated with plasma was at a low temperature of less than 50°C. From this, it was inferred that the apparatus used for plasma treatment should preferably be one that generates low-temperature plasma. The type of plasma method is not limited to the apparatus used in this experimental example; it was inferred that similar effects can be obtained with corona discharge, dielectric barrier discharge, microwave discharge, etc.

[0074]

[0075]

[0076]

[0077] Experimental examples 56 to 61 relating to the second embodiment were conducted as follows.

[0078] 1. Preparation and Mass Measurement of Electrodes to be Treated The positive electrode was prepared according to the following procedure. The mass was measured for each electrode to be treated. LiNi was used as the positive electrode active material. 0.5 Co 0.2 Mn 0.3 A positive electrode composite material containing 95% by mass of O2 (NCM) (manufactured by Toda Kogyo), 3% by mass of acetylene black (manufactured by Denka) as a conductive material, and 2% by mass of polyvinylidene fluoride (PVdF) (manufactured by Kureha) as a binder was coated onto one side of a 20 μm thick aluminum current collector foil to form the positive electrode. The basis weight of the positive electrode composite layer was 20 mg / cm².2 The thickness was 80 μm and the area was 20 mm x 50 mm.

[0079] 2. Low-temperature plasma treatment was performed on the electrodes to be treated using a Yamato Material plasma cleaner miniature plasma device PIPI. The low-temperature plasma treatment involved placing the electrodes in a chamber so that the electrode composite surface of the electrodes to be treated would be plasma-treated. After evacuating the chamber, a reaction gas was charged, the plasma mode was set to RIE (Reactive Ion Etching), the electrode-to-electrode distance was 80 mm, and a high-frequency voltage was applied between the parallel plate electrodes to generate plasma. The gas type, gas flow rate, high-frequency output, and treatment time were each one of the following: Gas: O2, N2, Ar (100% each) Gas flow rate: 15 ml / min High-frequency output: 200 W Treatment time (holding time after reaching each output): 10-180 seconds (3 seconds to reach 200 W)

[0080] 3. For the electrodes to be treated after ultrasonic treatment and plasma treatment, an ultrasonic device (Branson GCX-M-3FQ12, maximum output 500W, outer tank capacity 20L) was used. Water was placed in the washing tank (outer tank), 10 mL of water was placed in the glass container of the inner tank, and ultrasonic waves were applied from the transducer at the bottom of the outer tank. The electrodes to be treated were immersed in the device and ultrasonic treatment was performed at a temperature of 20°C while sweeping. The sweep conditions were the same for all tests: sweep width: ±1 kHz, sweep speed: 1000 sweep cycles / second. The ultrasonic frequency, treatment time, and output were as follows: Frequency: 80 kHz, Treatment time: 1 minute, Output: 500 W

[0081] 4. Mass Measurement and Asphalt Peeling Rate Measurement The mass of the treated electrode after ultrasonic treatment was measured. The asphalt peeling rate [%] was calculated by determining the amount of asphalt peeled off [mg] from the mass difference of the electrode before and after ultrasonic treatment, and determining the initial amount of asphalt [mg] from the basis weight and area of ​​the electrode asphalt layer in the initial electrode, and then calculating it using the following formula (1): Asphalt Peeling Rate = Amount of Asphalt Peeled / Initial Amount of Asphalt × 100 ...Formula (1)

[0082] 5. Surface analysis of the electrodes before and after XPS analysis was performed by XPS analysis. A PHI-550MC manufactured by ULVAC PHI was used for the analysis. The analysis conditions were as follows: X-ray source was Mg Kα (1253.6 eV), take-off angle was 45°, and the X-ray irradiation area was approximately 800 μmφ. The F1s spectrum of the XPS was waveform-separated into three components. The peak energy of LiF was set to 684.81 eV and PVdF to 687.5 eV, and the amount of each component was estimated using a half-width of 2.22 eV for both. In addition, the O1s spectrum was waveform-separated into three components and the amount of MO was estimated. The peak energies were set to 529.2 eV for 0s and 10s, 529.13 eV for 60s, and 529.43 eV for 180s. The full width at half maximum was set to 1.7 eV for 0s, 60s, and 180s, and 2.22 eV for 10s. XPS analysis involves irradiating a solid surface with X-rays and measuring the energy of the emitted photoelectrons. This allows for the analysis of elemental composition, chemical bonds, and surface functional groups within a few nanometers of the surface, and offers excellent quantitative analysis capabilities.

[0083] 6. TOF-SIMS Analysis Surface analysis was performed on the treated electrodes before and after plasma treatment using TOF-SIMS analysis. An IONTOF TOF-SIMS5 was used for the analysis, with the following conditions: primary ion Bi3++, analysis area 500 × 500 μm, 256 × 256 pixels, 1 shot / pixel, and 16 cumulative passes. In TOF-SIMS analysis, a primary ion beam is irradiated onto the sample surface, and the emitted secondary ions are analyzed by mass spectrometry. This allows for the analysis of the surface composition and molecular structure, and enables observation of elemental and molecular distribution at the nanoscale.

[0084] 7. SAICAS Analysis The cutting strength of the composite material was measured using SAICAS on the electrodes to be treated before and after plasma treatment. For the analysis, a SAICAS surface and interface physical property analysis system manufactured by Daipla Wintes was used. Cutting was performed from the electrode surface with a cutting edge with a blade width of 1 mm at a horizontal speed of 2 μm / sec and a vertical speed of 0.2 μm / sec, and the cutting strength was measured at a depth of 20 μm from the surface over a length of 500 μm. SAICAS analysis measures the mechanical properties of the surface and interface of the material. Cutting at an extremely shallow angle allows for continuous analysis of changes from the surface to the interface, and the shear strength and peel strength for each layer and depth can be determined.

[0085] [Experimental Example 56] Plasma treatment was not performed, and ultrasonic treatment was performed with a frequency of 80 kHz, an output of 500 W, and a processing time of 1 minute.

[0086] [Experimental Examples 57-59] For plasma treatment, the gas was O2, the gas flow rate was 15 ml / min, the high-frequency output was 200 W, and the time was 0-180 seconds. For ultrasonic treatment, the frequency was 80 kHz, the output was 500 W, and the processing time was 1 minute.

[0087] [Experimental Example 60] For plasma treatment, the gas was Ar, the gas flow rate was 15 ml / min, the high-frequency output was 200 W, and the time was 60 seconds. For ultrasonic treatment, the frequency was 80 kHz, the output was 500 W, and the processing time was 1 minute.

[0088] [Experimental Example 61] For plasma treatment, the gas was N2, the gas flow rate was 15 ml / min, the high-frequency output was 200 W, and the time was 60 seconds. For ultrasonic treatment, the frequency was 80 kHz, the output was 500 W, and the processing time was 1 minute.

[0089] [Results and Discussion] Table 4 summarizes the plasma treatment conditions, TOF-SIMS analysis results, XPS analysis results, SAICAS analysis results (cutting strength measurement results), and asphalt delamination rate for experimental examples 56 to 62. Figure 7 shows the relationship between plasma treatment time and asphalt delamination rate after underwater ultrasonic treatment in experimental examples 56 to 61. Figure 8 shows the XPS analysis results after plasma treatment in experimental examples 56 to 59. Figure 8A shows the F1s spectrum, and Figure 8B shows the O1s spectrum. Figure 9 shows the XPS analysis results after plasma treatment in experimental examples 56, 58, and 60 to 61. Figure 9A shows the F1s spectrum, and Figure 9B shows the O1s spectrum. Figure 10 shows the TOF-SIMS analysis results (positive ion spectra) after plasma treatment in experimental examples 56 to 59. Figure 10B shows a magnified view of Figure 10A around m / z = 113, and Figure 10C shows a magnified view of Figure 10A around m / z = 133. Figure 11 shows the TOF-SIMS analysis results (positive ion spectra) after plasma treatment in experimental examples 56, 58, and 60-61. Figure 11B shows a magnified view of Figure 11A around m / z = 113, and Figure 11C shows a magnified view of Figure 11A around m / z = 133. Figure 12 shows the relationship between plasma treatment time and the asphalt detachment rate after underwater ultrasonic treatment when the plasma treatment conditions and ultrasonic treatment conditions are changed.

[0090] As shown in Figure 8, the XPS analysis results confirmed that a reaction involving F, such as PVdF → LiF, progressed as the oxygen plasma treatment time increased (Figure 8A). It was inferred that the decomposition of PVdF progressed, the active material was exposed, and LiF was formed as a decomposition product from F• (fluorine radical) formed by the decomposition of PVdF and Li. In experimental examples 57 to 59, where oxygen plasma treatment was performed for 10 to 180 seconds, the PVdF peak in the F1s decreased with treatment time. As the oxygen plasma treatment time progressed, it was confirmed that the above reaction involving F progressed, and at the same time, the formation of metal oxide MO progressed as an O-related reaction (Figure 8B). Since the metal oxide layer acts as an insulating and inert barrier layer, it was inferred that it inhibits separation during physical sorting after plasma treatment. In Experiment 59, where oxygen plasma treatment was performed for 180 seconds, the rate of asphalt detachment by underwater ultrasonic delamination was lower than in Experiment 57, where oxygen plasma treatment was performed for 10 seconds, and in Experiment 58, where oxygen plasma treatment was performed for 60 seconds. This was presumed to be the reason for this decrease. At the same time, it was presumed that the formation of metal oxides may increase the resistance of the active material and cause structural instability. Compared to the untreated oxygen plasma sample, LiF tended to increase as the treatment time increased to 10s, 60s, and 180s, which was presumed to indicate that the decomposition of PVdF was progressing. Simultaneously, MO increased with increasing treatment time, and it was presumed that LiF relatively decreased, especially at a treatment time of 180s, due to the formation of MO. From the above, it was found that the peeling rate of the electrode mixture can be further increased by performing plasma treatment under conditions that suitably decompose PVdF in the electrode mixture, for example, by satisfying one or more of the following conditions: the proportion of fluorine derived from PVdF as determined by XPS analysis decreases to 5 at% or less, or is 0.4 times or less than before plasma treatment. Furthermore, it was found that the peeling rate of the electrode mixture can be further increased by performing plasma treatment under conditions that allow a suitable amount of LiF to be formed when PVdF decomposes, for example, by satisfying one or more of the following conditions: the proportion of fluorine derived from LiF as determined by XPS analysis is 15 at% or more, or is 15 times or more than before plasma treatment.Furthermore, it was found that the aggregate peeling rate can be further increased by performing plasma treatment under conditions that do not allow excessive metal oxide formation, for example, by satisfying one or more of the following: the proportion of oxygen derived from metal oxides determined by XPS analysis is 10 at% or less, the proportion of fluorine derived from polyvinylidene fluoride determined by XPS analysis is 5 times or less, or the proportion of fluorine derived from LiF determined by XPS analysis is 0.5 times or less. It was also inferred that the oxygen plasma treatment should preferably be performed within a range where PVdF is removed, LiF is formed, and the generation of metal oxides does not become excessive, preferably within a range of more than 10 seconds but less than 180 seconds, and more preferably within a range of 30 seconds to 120 seconds.

[0091] As shown in Figure 9, the XPS analysis results confirm that in both Ar and N2 plasmas, reactions involving F, such as PVdF → LiF, proceed as the plasma treatment time progresses, and the degree of this progression is O2 > Ar ≈ N2 (Figure 9A). Furthermore, in both Ar and N2 plasmas, the formation of metal oxides, involving O, progresses as the plasma treatment time progresses, and the degree of this progression is Ar > N2 > O2 (Figure 9B). In O2 plasma, unlike simple physical sputtering with Ar plasma, etc., or neutral excitation with N2 plasma, etc., strong oxidative radical species (O• and O2) are generated. - It was hypothesized that the C-F bond of PVdF is effectively cleaved and decomposition is promoted because a compound is generated. Furthermore, it was hypothesized that the oxide produced by the O2 plasma tends to form locally and uniformly on the surface, and is unlikely to form a thick barrier layer that hinders reactivity. It was hypothesized that PVdF is oxidized and decomposed by the oxygen plasma, for example as shown in equation (2) below, generating gases such as HF and CO2, while fluorine radicals (F•) and HF remain on the surface, which then become precursors to LiF. -[CH2-CF2] n -+O・→HF+CO / CO2+CF xRadical + H2O ...Equation (2) On the other hand, in Ar plasma, the sputtering effect is high, so the electrode surface is severely destroyed, exposing a fresh metal surface that rapidly oxidizes upon exposure to air, and it was inferred that the formation of metal oxides proceeds easily. In addition, in N2 plasma, the surface is easily activated by N radicals and excited species, creating a base for reaction with oxygen, and it was inferred that metal oxides are formed in excess. These metal oxides are chemically inert and have low reactivity with F radicals, so it was inferred that the decomposition products of PVdF (F• and HF, etc.) may recombine without forming LiF. From the above, comparing the gas species, it was inferred that O2 plasma had the highest decomposition effect of PVdF, less metal oxide formation, and achieved both binder removal and suppression of metal oxide formation, making it suitable for reuse of the composite material. Considering the results of underwater ultrasonic treatment after various plasma treatments shown in Figures 7 and 12, oxygen plasma treatment had the highest peeling effect in a short time plasma treatment.

[0092] As shown in Figures 10 and 11, in the electrodes of experimental examples 57 to 61 that underwent plasma treatment, TOF-SIMS analysis revealed a PVdF fragment (C3HF4, where the mass-to-charge ratio m / z originating from PVdF in the positive ion spectrum is located at 113). + C3H2F5 is located at the peak and 133. + The peak (of PVdF) disappeared. In the electrodes of experimental examples 57 to 61, the rate of material delamination by underwater ultrasonic delamination was higher than in experimental example 56, which was not treated with plasma, and it was inferred that the disappearance of the PVdF peak in TOF-SIMS is an indicator of a decrease in the bonding strength of the binder.

[0093] SAICAS analysis showed that the cutting strength of the electrode in experimental example 56, which was not treated with plasma, was 0.202 kN / m. In experimental examples 57, 58, and 59, which underwent oxygen plasma treatment, the cutting strength decreased as the plasma treatment time increased, confirming that plasma treatment reduced the mechanical bonding strength, which is evidence of PVdF decomposition. In example 60, which underwent Ar plasma treatment, and example 61, which underwent N2 plasma treatment, the cutting strength was also reduced compared to the untreated sample. SAICAS analysis revealed that the peeling rate of the asphalt mixture could be further increased by performing plasma treatment under conditions such that the cutting strength of the asphalt mixture after plasma treatment was 70% or less of the cutting strength of the asphalt mixture before plasma treatment. However, there was no correlation between lower bonding strength and higher peeling rate. From this, it was inferred that not only the reduction in bonding strength affects the peeling rate, but also that the inhibition of peeling by metal oxides (MO) as shown by XPS is involved.

[0094] From experimental examples 56 to 61, it was found that the plasma treatment in experimental examples 57 to 61 not only has a hydrophilic effect but also has the effect of decomposing the PVdF of the binder. By utilizing this, it is possible not only to separate the current collector and the electrode mixture but also to decompose and remove the binder contained in the electrode mixture. Furthermore, it was inferred that separation of the current collector and the electrode mixture, as well as decomposition and removal of the binder contained in the electrode mixture, would be possible even if the ultrasonic process were omitted.

[0095]

[0096] This application is based on the priority claim of Japanese Patent Application No. 2024-157979, filed on 12 September 2024, and Japanese Patent Application No. 2025-148250, filed on 8 September 2025, the entire contents of which are incorporated herein by reference.

[0097] This disclosure is applicable to the field of the battery industry.

[0098] 10 Separation device, 15 Control unit, 20 Plasma unit, 22 Chamber, 24a Flat plate electrode, 24b Flat plate electrode, 26 Capacitor, 28 High-frequency power supply, 30 Ultrasonic unit, 32 Processing container, 34 Inner tank, 35 Mounting platform, 36 Outer tank, 38 Transducer, 40 Oscillator, 42 Processed water, 43 Processed water containing composite material, 46 Ultrasonic propagation medium, 50, 50A Electrode to be processed, 52 Current collector, 54, 54A Electrode composite material.

Claims

1. A separation method comprising: a hydrophilization step of performing a hydrophilization treatment on an electrode to be treated, which comprises a current collector and an electrode mixture formed on the current collector; and an ultrasonic step of performing ultrasonic treatment on the electrode to be treated after the hydrophilization treatment while sweeping the frequency of ultrasonic waves in treated water to separate the current collector and the electrode mixture.

2. The separation method according to claim 1, wherein the hydrophilization step is performed by performing plasma treatment as the hydrophilization treatment.

3. The separation method according to claim 2, wherein the plasma treatment is performed using an oxygen-containing gas in the hydrophilization step.

4. The separation method according to claim 2 or 3, wherein in the hydrophilization step, the plasma treatment is performed under conditions that the contact angle between the electrode mixture surface and the treated water is 10° or less.

5. The separation method according to claim 2 or 3, wherein the hydrophilization step is performed under conditions that satisfy one or more of the following (1) to (6): (1) The plasma treatment is performed within a range of 3 minutes or less. (2) The plasma treatment is performed in a gas containing one or more of oxygen, nitrogen, and argon. (3) The plasma treatment is performed on a surface area of ​​10 cm² of the electrode mixture. 2 (4) The plasma treatment is performed under a gas flow rate of 1 mL / min to 50 mL / min per unit area. (5) The plasma treatment is performed at a plasma temperature of 0°C to 200°C. 2 (6) The plasma treatment shall be carried out under reduced pressure or atmospheric pressure.

6. The separation method according to any one of claims 1 to 3, wherein the ultrasonic process satisfies at least one of the following: the sweep is performed around a fundamental frequency of 80 kHz or more and 200 kHz or the sweep is performed with a sweep width of ±3 kHz or less around the fundamental frequency.

7. The separation method according to any one of claims 1 to 3, wherein the ultrasonic process is performed within a range of 10 minutes or less.

8. The separation method according to any one of claims 1 to 3, wherein the electrode to be processed includes a solvent-based binder.

9. A processing method comprising a plasma step of performing plasma treatment on an electrode mixture containing polyvinylidene fluoride so that one or more of the following conditions (7) and (8) are met: (7) The proportion of fluorine derived from polyvinylidene fluoride as determined by XPS analysis is reduced to 5 at% or less. (8) The proportion of fluorine derived from polyvinylidene fluoride as determined by XPS analysis is 0.4 times or less than that before the plasma treatment.

10. The processing method according to claim 9, wherein the plasma process is performed on the electrode mixture so that one or more of the following conditions (9) and (10) are met: (9) The proportion of fluorine derived from LiF as determined by XPS analysis is 15 at% or more. (10) The proportion of fluorine derived from LiF as determined by XPS analysis is 15 times or more than before the plasma processing.

11. The processing method according to claim 9 or 10, wherein the plasma process is performed on the electrode mixture so that one or more of the following conditions (11) to (13) are met: (11) The proportion of oxygen derived from metal oxides determined by XPS analysis is 10 at% or less. (12) The proportion of oxygen derived from metal oxides determined by XPS analysis is 5 times or less the proportion of fluorine derived from polyvinylidene fluoride determined by XPS analysis. (13) The proportion of oxygen derived from metal oxides determined by XPS analysis is 0.5 times or less the proportion of fluorine derived from LiF determined by XPS analysis.

12. The processing method according to claim 9 or 10, wherein in the plasma step, the plasma process is performed on the electrode mixture such that the peak intensities of the mass charge ratio m / z of 113 and 133 in the positive ion spectrum obtained by TOF-SIMS analysis are each 1 / 100 or less of the intensities before the plasma process.

13. The processing method according to claim 9 or 10, wherein the plasma step involves performing oxygen plasma treatment on the electrode mixture for a period of 10 seconds or more and less than 180 seconds.

14. The processing method according to claim 9 or 10, wherein the electrode mixture is formed on a current collector, and in the plasma process, the plasma process is performed such that the cutting strength of the electrode mixture by SAICAS is 70% or less of that before the plasma process.

15. A processing method according to claim 9 or 10, wherein the electrode mixture is formed on a current collector, and the processing method includes a post-processing step of separating the current collector and the electrode mixture after the plasma process.

16. A processing method according to claim 9 or 10, comprising a pre-processing step of recovering the powdered electrode mixture prior to the plasma step.

17. A method for manufacturing an electrode, comprising an electrode manufacturing step of manufacturing a new electrode using at least one of the electrode composite material and the current collector obtained by the separation method described in any one of claims 1 to 3.

18. A method for manufacturing an electrode, comprising an electrode manufacturing step of manufacturing a new electrode using the electrode composite material processed by the processing method described in claim 9 or 10.

19. A separation device comprising: a hydrophilization unit that performs hydrophilization treatment on an electrode to be treated, which comprises a current collector and an electrode mixture formed on the current collector; an ultrasonic unit that performs ultrasonic treatment on the electrode to be treated after the hydrophilization treatment in treated water to separate the current collector and the electrode mixture; and a control unit that controls the ultrasonic unit to perform the ultrasonic treatment while sweeping the frequency of the ultrasonic waves.

20. A processing apparatus equipped with a plasma section that performs plasma treatment on an electrode mixture containing polyvinylidene fluoride so that one or more of the following conditions (7) and (8) are met: (7) The proportion of fluorine derived from polyvinylidene fluoride, as determined by XPS analysis, is reduced to 5 at% or less. (8) The proportion of fluorine derived from polyvinylidene fluoride, as determined by XPS analysis, is 0.4 times or less than that before the plasma treatment.

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