Separation method, electrode manufacturing method, and separation apparatus

Abstract

This allows for more efficient separation of the current collector and the electrode composite material. [Solution] The separation method includes a UV step of irradiating an electrode to be treated, which comprises a current collector and an electrode composite formed on the current collector, with ultraviolet light, and an ultrasonic step of performing ultrasonic treatment on the electrode to be treated after ultraviolet irradiation in treated water while sweeping the frequency of the ultrasonic waves to separate the current collector and the electrode composite. The separation device comprises a UV unit that irradiates an electrode to be treated, which comprises a current collector and an electrode composite formed on the current collector, an ultrasonic unit that performs ultrasonic treatment on the electrode to be treated after ultraviolet irradiation in treated water to separate the current collector and the electrode composite, and a control unit that controls the ultrasonic unit to perform ultrasonic treatment while sweeping the frequency of the ultrasonic waves.

Description

[Technical Field]

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

[0002] Conventionally, a method has been proposed for separating the current collector and electrode composite material during battery recycling by ultrasonic treatment while sweeping the ultrasonic frequency 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. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-102744 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, with the methods described above, separating the current collector from the electrode mixture can be time-consuming, especially when processing electrodes with thick or high-density electrode mixture layers. Therefore, a more efficient method for separating the current collector from the electrode mixture was desired.

[0005] This disclosure was made to solve these problems, and its main purpose is to more efficiently separate the current collector and the electrode mixture. [Means for solving the problem]

[0006] In order to achieve the above object, the inventors of the present invention found that when ultraviolet irradiation is performed on a processing target electrode including a current collector and an electrode mixture formed on the current collector, and then ultrasonic treatment is performed while sweeping the frequency of ultrasonic waves in the processing water, the current collector and the electrode mixture can be efficiently separated, and thus the present disclosure has been completed.

[0007] That is, the separation method of the present disclosure is a UV step of performing ultraviolet irradiation on a processing target electrode including a current collector and an electrode mixture formed on the current collector, an ultrasonic step of performing ultrasonic treatment while sweeping the frequency of ultrasonic waves in the processing water on the processing target electrode after the ultraviolet irradiation to separate the current collector and the electrode mixture, and includes these.

[0008] In addition, the method for manufacturing an electrode of the present disclosure includes an electrode manufacturing step of manufacturing a new electrode using at least one of the electrode mixture and the current collector obtained by the above-described separation method.

[0009] In addition, the separation device of the present disclosure includes a UV unit that performs ultraviolet irradiation on a processing target electrode including a current collector and an electrode mixture formed on the current collector, an ultrasonic unit that performs ultrasonic treatment on the processing target electrode after the ultraviolet irradiation in the processing water to separate the current collector and the electrode mixture, and a control unit that controls the ultrasonic unit so as to perform the ultrasonic treatment while sweeping the frequency of ultrasonic waves, and is provided with these.

Advantages of the Invention

[0010] 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, ultraviolet irradiation is performed prior to ultrasonic treatment in the treated water. This is presumed to increase the hydrophilicity of the electrode mixture, making it easier for the treated water to permeate, and allowing the cavitation effect to be suitably expressed in the electrode during ultrasonic treatment, thereby enabling more efficient separation of the current collector and the electrode mixture. [Brief explanation of the drawing]

[0011] [Figure 1] Diagram illustrating sweep and sweep cycle. [Figure 2] Diagram illustrating the sweep width. [Figure 3] An explanatory diagram showing the general configuration of the separation device 10. [Figure 4] An explanatory diagram showing the general configuration of the UV section 20. [Figure 5] An explanatory diagram showing the general configuration of the ultrasonic section 30. [Figure 6] A flowchart showing the procedures for Experimental Examples 1-35. [Modes for carrying out the invention]

[0012] [Separation method] The separation method of this disclosure includes a UV step of irradiating the electrode to be treated with ultraviolet light, and an ultrasonic step of performing ultrasonic treatment on the electrode after ultraviolet irradiation in treated water to separate the current collector and the electrode composite material.

[0013] (Electrode to be processed) The electrode to be processed includes a current collector and an electrode mixture formed on the current collector. The electrode to be processed is an electrode of a storage device such as an ion secondary battery like a lithium ion secondary battery, an electric double layer capacitor, a hybrid capacitor, a pseudocapacitor, etc., and may be taken from a used or deteriorated storage device. The electrode to be processed may be a positive electrode, a negative electrode, or a bipolar electrode with a positive electrode mixture formed on one surface and a negative electrode mixture formed on the other surface. The electrode to be processed may be left as it is taken out from the storage device without being shredded, for example, with an area of 3 cm 2 or more or 5 cm 2 or more, 10 cm 2 or more.

[0014] 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.

[0015] The electrode mixture may include an electrode active material, a binder, and a conductive material etc. as required. The electrode mixture may be, for example, formed by mixing an electrode active material, a conductive material, and a binder, adding an appropriate solvent to make it paste-like, applying it to the surface of the current collector and drying it, and compressing it as required to increase the electrode density. The electrode mixture may be formed on one side or both sides of the current collector.

[0016] Examples of the electrode active material contained in the electrode mixture include transition metal sulfides such as TiS2, TiS3, MoS3, FeS2, etc., lithium manganese composite oxides with a basic composition formula of Li (1-x) MnO2 (0 < x < 1, etc., the same below) or Li (1-x) Mn2O4, etc., and lithium-based materials with a basic composition formula of Li (1-x)Lithium cobalt composite oxides such as CoO2, with a basic composition formula of Li (1-x) Lithium nickel composite oxides such as NiO2, with a basic composition formula of Li (1-x) Ni a Co b Mn c Lithium nickel cobalt manganese composite oxides such as O2(a + b + c = 1), lithium vanadium composite oxides with a basic composition formula of LiV2O3, transition metal oxides with a basic composition formula of V2O5, lithium iron phosphate, etc., and active materials used for the positive electrode of a lithium-ion secondary battery are mentioned. The electrode active material may include a layered rock salt type active material such as a lithium nickel cobalt manganese composite oxide among these. Note that the "basic composition formula" means that it may contain other elements such as Al and Mg. Also, as the electrode active material, for example, active materials used for the positive electrode and / or negative electrode of a capacitor or a lithium-ion capacitor such as activated carbons, cokes, glassy carbons, graphites, non-graphitizable carbons, pyrolytic carbons, carbon fibers, carbon nanotubes, polyacenes, etc. are mentioned. Further, as the electrode active material, for example, active materials used for the negative electrode of a lithium-ion secondary battery such as lithium alloys, inorganic compounds such as tin compounds, carbonaceous materials capable of occluding and releasing lithium ions, composite oxides containing a plurality of elements, conductive polymers, etc. are mentioned. Examples of the carbonaceous material include cokes, glassy carbons, graphites, non-graphitizable carbons, pyrolytic carbons, carbon fibers, etc. Examples of the composite oxide include lithium titanium composite oxides and lithium vanadium composite oxides, etc. Examples of the conductive material contained in the electrode composite include graphites such as natural graphite (scaly graphite, flaky graphite) and artificial graphite, acetylene black, carbon black, ketjen black, carbon whiskers, needle coke, carbon fibers, metals (copper, nickel, aluminum, silver, gold, etc.), etc.

[0017] 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.

[0018] The basis weight of the electrode composite layer is, for example, 5 mg / cm³. 2 The above is also acceptable: 10 mg / cm³ 2 The above is also acceptable: 20 mg / cm³ 2The above may also be used. Furthermore, the thickness of the electrode composite layer may be, for example, 20 μm or more, 40 μm or more, or 60 μm or more. Furthermore, the density of the electrode composite layer may be, for example, 2 g / cm³. 3 The above is also acceptable, 2.5 g / cm³ 3 The above is also acceptable: 3 g / cm³ 3 The above may also be used. When the electrode mixture layer has a high basis weight, is thick, or has a high density, the treated water does not easily seep into the electrode mixture layer, and the separation of the current collector and the electrode mixture tends to take time, so there is a high significance in applying this disclosure.

[0019] (UV process) In the UV process, the electrode to be treated is irradiated with ultraviolet light (hereinafter also referred to as UV treatment). From the viewpoint of improving the asphalt detachment rate by ultrasonic treatment (hereinafter simply referred to as asphalt detachment rate), a shorter wavelength of ultraviolet light is preferable. For example, 350 nm or less is preferable, 300 nm or less is more preferable, and 260 nm or less is even preferable. The wavelength of ultraviolet light can be appropriately adjusted according to the irradiance of the ultraviolet light and the thickness of the electrode asphalt layer. For example, it may be 200 nm or less, 180 nm or less, or 100 nm or more, 150 nm or more, or 180 nm or more. The ultraviolet light may have two or more different wavelength components. For example, the ultraviolet light may have a wavelength of 172 nm, or a combination of wavelengths 185 nm and 254 nm. From the viewpoint of improving the asphalt detachment rate, it is preferable to perform the ultraviolet irradiation under conditions that result in a smaller contact angle between the electrode asphalt surface and the treated water. The contact angle is preferably 100° or less, more preferably 90° or less, and even more preferably 80° or less. When the electrode composite layer is thick (e.g., 50 μm or more), the contact angle is preferably 70° or less, and more preferably 50° or less. The contact angle may also be, for example, 10° or more. When the electrode composite layer is thin (e.g., 30 μm or less), a contact angle of, for example, 50° or more or 70° or more can achieve a composite peel rate of 95% or more. The treated water used for measuring the contact angle is the same as the treated water used for ultrasonic treatment (before ultrasonic treatment). From the viewpoint of improving the composite peel rate, a longer UV irradiation time is preferable, for example, 1 minute or more is preferable, 2 minutes or more is more preferable, and 3 minutes or more is even preferable. When the electrode composite layer is thick (e.g., 50 μm or more), a longer UV irradiation time is preferable, for example, 5 minutes or more is preferable, 10 minutes or more is more preferable, and 20 minutes or more is even preferable. From the viewpoint of shortening the UV process time, a shorter UV irradiation time is preferable, for example, 1 hour or less is preferable, 45 minutes or less is more preferable, and 30 minutes or less is even preferable. When the thickness of the electrode composite layer is thin (e.g., 30 μm or less), a composite peel rate of 95% or more can be achieved with UV irradiation times of, for example, 20 minutes or less, 10 minutes or less, or 5 minutes or less. From the viewpoint of improving the composite peel rate with short UV irradiation times, a higher UV intensity is preferable, for example, 5 mW / cm². 2 The above is preferable, and 10 mW / cm²2 The above is more preferable: 20 mW / cm² 2 The above is even more preferable. From the viewpoint of energy consumption, a lower ultraviolet irradiance is preferable, preferably 200 mW / cm². 2 The following is also acceptable: 100 mW / cm² 2 The following is also acceptable: 50 mW / cm² 2 The following may also be used: UV irradiance [mW / cm²] 2 ] × Irradiation time [seconds] = Total light intensity [mJ / cm] 2 The integrated light intensity represented by [ ] is preferably high from the viewpoint of improving the asphalt detachment rate, for example, 10 mJ / cm². 2 The above is preferable, and 100 mJ / cm² is preferred. 2 The above is more preferable, specifically 200 mJ / cm². 2 The above is even more preferable. From the viewpoint of energy saving, a lower cumulative light intensity is preferable, for example, 5000 mJ / cm². 2 The following is preferable: 2000 mJ / cm² 2 The following is more preferable: 1000 mJ / cm² 2 The following are even more preferable.

[0020] Ultraviolet irradiation is preferably carried out in an oxygen-containing atmosphere, such as an atmospheric atmosphere. This is because ultraviolet light acts on oxygen molecules to generate ozone, which generates oxygen radicals. These oxygen radicals react with the surface of the asphalt mixture, and oxidative functional groups are imparted to the surface of the asphalt mixture, thereby promoting hydrophilization of the electrode mixture and improving the asphalt mixture peel rate. However, if the oxygen content in the atmosphere is too high, the ultraviolet light may be absorbed by the oxygen, reducing the effect of improving the asphalt mixture peel rate. Therefore, the oxygen content in the atmosphere is preferably 30% or less, more preferably 25% or less, and even more preferably 21% or less. The oxygen content in the atmosphere may be 0.01% or more, 0.05% or more, or 0.1% or more. From the viewpoint of generating ozone, it is preferable that the ultraviolet light contains wavelength components of 200 nm or less. Furthermore, from the viewpoint of activating ozone, it is preferable that the ultraviolet light contains wavelength components of 240 nm to 340 nm. When irradiating with ultraviolet light, it is preferable to keep the distance from the light source, such as a lamp, to the electrode being treated (irradiation distance) short in order to suppress light attenuation and enhance the effect of improving the asphalt peel rate. The irradiation distance is preferably 25 mm or less, more preferably 10 mm or less, and even more preferably 5 mm or less. The irradiation distance may also be, for example, 1 mm or more.

[0021] It is preferable to perform ultraviolet irradiation without heating by a heater or the like. Although ultraviolet irradiation may raise the temperature of the electrode or stage being treated to, for example, around 50°C, this temperature rise due to ultraviolet irradiation is not included in the heating referred to here.

[0022] (Ultrasonic process) In the ultrasonic process, the electrode to be treated after UV treatment is subjected to ultrasonic treatment while immersed in treatment water (with the electrode submerged in the treatment water), with the ultrasonic frequency being swept. 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.

[0023] In ultrasonic treatment, the ultrasonic frequency may be periodically varied 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 at its minimum frequency Fmin to the falling edge of the wave at its maximum frequency Fmax (see Figure 1). 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. Alternatively, 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 at its minimum frequency Fmin to the rising edge of the next wave at its minimum frequency Fmin.

[0024] 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 material peeling 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.

[0025] Ultrasonic treatment reduces the contact area between the current collector and the electrode composite material by A [cm²]. 2When 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: 30W / cm² 2 The following is also acceptable: Power density B / A is 10 W / cm². 2 The above is also acceptable: 50W / cm² 2 You may leave it at that.

[0026] 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.

[0027] The treated water used in ultrasonic treatment 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 become hydrophilic due to UV treatment, allowing the cavitation effect of ultrasound to be efficiently realized. Furthermore, since the treated water does not require organic solvents, it is preferable from the viewpoint of reducing environmental impact.

[0028] 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.

[0029] 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.

[0030] 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 this separation method yields current collectors and electrode mixtures, this separation method is also a method for manufacturing current collectors and electrode mixtures.

[0031] Before the UV process, an extraction process may be performed to remove electrodes from the energy storage device. The electrodes removed in the extraction process can be used as is, without being shredded, or in a 1cm² area. 2 The electrodes may be cut into pieces as described above and used as electrodes to be processed. Furthermore, a removal treatment may be performed before the UV process to remove organic solvents contained in the electrodes (for example, organic solvents originating from the electrolyte of an energy storage device). This removal treatment may be performed by heating under an inert atmosphere.

[0032] [Separation device] The separation apparatus of this disclosure comprises a UV unit that irradiates the electrode to be processed with ultraviolet light, an ultrasonic unit that performs ultrasonic treatment on the electrode after ultraviolet irradiation in treated water to separate the current collector and the electrode composite material, and a control unit that controls the ultrasonic unit. This separation apparatus may perform the separation method described above, or it may apply the configuration and conditions described in the separation method described above.

[0033] Hereinafter, a separation device 10 will be described as an example of the separation device of this disclosure. Figure 3 shows an explanatory diagram illustrating the general configuration of the separation device 10. As shown in Figure 3, the separation device 10 includes a UV unit 20, an ultrasonic unit 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 UV unit 20. Figure 5 shows an explanatory diagram illustrating the general configuration of the ultrasonic unit 30. Figure 5A is an explanatory diagram illustrating the general configuration of the ultrasonic unit 30 before ultrasonic treatment. Figure 5B is an explanatory diagram illustrating the general configuration of the ultrasonic unit 30 after ultrasonic treatment. In this separation device 10, a target electrode 50 comprising a current collector 52 and an electrode mixture 54 is processed 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.

[0034] The UV unit 20 is configured as an ultraviolet irradiation device that irradiates the surface of the electrode mixture 54 of the electrode 50 to be processed with ultraviolet light. As shown in Figure 4, the UV unit 20 has a processing chamber 22 equipped with a lamp 21, which is an ultraviolet light source. Suitable lamps for the lamp 21 include, for example, an excimer lamp, a low-pressure mercury lamp, or an LED lamp. It is believed that at least a portion of the electrode mixture 54 of the electrode 50 to be processed becomes hydrophilic due to ultraviolet irradiation in the UV unit 20. As a result, the electrode 50 to be processed becomes an electrode 50A (Figure 5) equipped with the electrode mixture 54A after ultraviolet irradiation. The ultraviolet irradiation in the UV unit 20 may be performed as a batch-type fixed irradiation with the electrode 50 to be processed fixed, or as a continuous-type scan irradiation while the electrode 50 to be processed is transported.

[0035] The ultrasonic unit 30 is configured as an ultrasonic treatment apparatus that performs ultrasonic treatment on the electrode 50A to be treated after ultraviolet irradiation 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 the 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.

[0036] 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 lamp 21 of the UV 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 lamp 21 of the UV unit 20 so that the lamp 21 generates ultraviolet light under predetermined conditions (ultraviolet wavelength, ultraviolet irradiance, ultraviolet irradiation time, integrated light amount, etc.). The conditions for ultraviolet irradiation 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.

[0037] An example of the operation of the separation device 10 will be described. First, the control unit 15 controls the lamp 21 of the UV unit 20 so that the lamp 21 generates ultraviolet light under predetermined conditions, and irradiates the surface of the electrode mixture 54A with ultraviolet light. The wavelength of the ultraviolet light is, for example, 260 nm or less. The irradiance of the ultraviolet light is, for example, 50 mV / cm 2 The following applies: The UV irradiation time shall be, for example, 30 minutes or less. It is believed that such UV irradiation will cause at least a portion of the electrode mixture 54 of the electrode 50 to be treated to become hydrophilic (its hydrophilicity will increase). As a result, the electrode 50 to be treated becomes the electrode 50A equipped with the electrode mixture 54A after UV irradiation.

[0038] Next, treated water 42 is placed in the treatment container 32, and the electrode 50A to be treated after UV irradiation 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 and controls the oscillator 40 to sweep the frequency 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.

[0039] 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 as follows: In this separation method and apparatus, ultrasonic treatment is performed in the treated water. At that time, the ultrasonic treatment is performed while sweeping the ultrasonic frequency, so 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, ultraviolet irradiation is performed on the electrode to be treated. This is presumed to increase the hydrophilicity of the electrode mixture, making it easier for the treated water to permeate, and allowing the cavitation effect to be favorably expressed in the electrode during ultrasonic treatment, thereby enabling 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. It is presumed that the hydrophilicity of the asphalt mixture due to UV irradiation occurs because UV light acts on oxygen molecules in the treatment atmosphere, generating ozone and oxygen radicals. These oxygen radicals then react with the surface of the asphalt mixture, imparting oxidative functional groups. Alternatively, it is presumed that UV light acts on the binder, causing it to decompose and become hydrophilic.

[0040] Furthermore, since electrode composites and current collectors can be obtained using the separation methods and apparatus described above, new electrodes can be manufactured 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 manufacture 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.

[0041] It goes without saying that this disclosure is not limited in any way to the embodiments described above, and can be implemented in various forms as long as they fall within the technical scope of this disclosure.

[0042] For example, in the embodiment described above, the separation device 10 performs UV treatment and ultrasonic treatment in a batch manner, but it may also perform UV treatment and ultrasonic treatment in a continuous manner.

[0043] This disclosure may be any of the following [1] to

[10] . [1] A separation method comprising: a UV step of irradiating an electrode to be treated, which comprises a current collector and an electrode composite formed on the current collector, with ultraviolet light; and an ultrasonic step of performing ultrasonic treatment on the electrode to be treated after the ultraviolet light irradiation in treatment water while sweeping the frequency of ultrasonic waves to separate the current collector and the electrode composite. [2] The separation method according to [1], wherein the UV step is performed by irradiating with ultraviolet light with a wavelength of 260 nm or less. [3] The separation method according to [1] or [2], wherein the UV step is performed under conditions that the contact angle between the electrode mixture surface and the treated water is 90° or less. [4] The separation method according to any one of [1] to [3], wherein the UV step is performed for a period of 30 minutes or less. [5] In the UV process, the illuminance was 50 mV / cm 2 The separation method according to any one of [1] to [4], wherein the ultraviolet irradiation is performed with the following ultraviolet light. [6] The separation method according to any one of [1] to [5], wherein the ultrasonic step is performed with a sweep centered on a fundamental frequency of 80 kHz or more and 200 kHz or with a sweep width of ±3 kHz or less centered on the fundamental frequency. [7] The separation method according to any one of [1] to [6], wherein the ultrasonic process is performed within a range of 10 minutes or less. [8] The separation method according to any one of [1] to [7], wherein the electrode to be processed includes a solvent-based binder. 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 [1] to [8].

[10] A separation device comprising: a UV unit that irradiates an electrode to be treated, which comprises a current collector and an electrode mixture formed on the current collector, with ultraviolet light; an ultrasonic unit that performs ultrasonic treatment on the electrode to be treated after ultraviolet light irradiation in treatment 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. [Examples]

[0044] The following describes examples of implementing the separation method of this disclosure. Experimental Examples 2-20, 22-28, 30, and 32-35 correspond to the embodiments of this disclosure, while Experimental Examples 1, 21, 29, and 31 correspond to comparative examples.

[0045] Experimental examples 1 to 35 were carried out according to the procedure shown in Figure 6.

[0046] 1. Preparation of the electrode to be processed and measurement of its mass. Positive electrode A and positive electrode B were prepared according to the following procedure. Mass measurements were performed on each electrode to be processed. (A) Positive electrode A (thick film, high density) LiNi 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 × 50 mm. (B) Positive electrode B (thin film, low density) LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 A positive electrode composite material containing 92% by mass of O2(NCM) (manufactured by Toda Kogyo), 5% by mass of acetylene black (manufactured by Denka) as a conductive material, and 3% 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 5 mg / cm². 2The thickness was 20 μm and the area was 20 mm × 50 mm.

[0047] 2. UV treatment (ultraviolet irradiation) The electrodes were placed in each UV treatment device so that UV light was irradiated onto the electrode composite surface of the electrodes to be treated under one of the following conditions A to C, and UV irradiation was performed for 1 to 30 minutes. Alternatively, no UV treatment was performed. (A) Condition A / Wavelength: 172nm, UV illuminance: 10mV / cm 2 Lamp: Excimer, UV treatment device: Ushio Inc. Mini-Excimer (B) Condition B / Wavelength: 185nm+254nm, UV illuminance: 28mV / cm 2 Lamp: Low-pressure mercury, UV treatment device: Filgen UV ozone cleaner (C) Condition C / Wavelength: 365nm, UV illuminance: 200mV / cm 2 Lamp: LED, UV treatment device: CCS UV irradiation device (D) No UV treatment

[0048] 3. Contact angle measurement The contact angle of the electrode composite surface was measured for the treated electrode after UV treatment. The contact angle was measured using a Kyowa Interface Chemical automatic contact angle meter DM-501, with pure water, a liquid volume of 1 μl, a time of 1 second, a temperature of 25°C, using the droplet method and the θ / 2 method. Five measurements were taken, and the average value was calculated.

[0049] 4. Ultrasonic treatment For electrodes treated with UV light, 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), 10mL 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 were then immersed in the device and ultrasonic treatment was performed at a temperature of 20°C while sweeping, under one of the following conditions A to D. In all cases, the sweep conditions were: sweep width: ±1kHz, sweep speed: 1000 sweep cycles / second. (A) Condition A Frequency: 80kHz, Processing time: 1 minute, Output: 500W (B) Condition B Frequency: 120kHz, Processing time: 3 minutes, Output: 500W (C) Condition C Frequency: 170kHz, Processing time: 1 minute, Output: 250W (D) Condition D Frequency: 120kHz, Processing time: 1 minute, Output: 100W

[0050] 5. Mass measurement and measurement of asphalt material delamination rate Mass measurements were performed on the electrodes after ultrasonic treatment. The asphalt detachment rate [%] was calculated by determining the amount of asphalt detachment [mg] from the mass difference of the electrodes 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 detachment rate = Amount of asphalt detachment / Initial amount of asphalt × 100 ... Equation (1)

[0051] [Experimental Example 1] The electrode to be treated was positive electrode A, no UV treatment was performed, and ultrasonic treatment was performed under condition A. [Experimental Examples 2-8] The electrode to be treated was positive electrode A, UV treatment was performed under condition A, and ultrasonic treatment was performed under condition A. [Experimental Examples 9-14] The electrode to be treated was positive electrode A, UV treatment was performed under condition B, and ultrasonic treatment was performed under condition A. [Experimental Examples 15-20] The electrode to be treated was positive electrode A, UV treatment was performed under condition C, and ultrasonic treatment was performed under condition A. [Experimental Example 21] The electrode to be treated was positive electrode A, with no UV treatment and ultrasonic treatment under condition B. [Experimental Examples 22-28] The electrode to be treated was positive electrode A, UV treatment was performed under condition B, and ultrasonic treatment was also performed under condition B. [Experimental Example 29] The electrode to be treated was positive electrode B, no UV treatment was performed, and ultrasonic treatment was performed under condition C. [Experimental Example 30] The electrode to be treated was positive electrode B, UV treatment was performed under condition A, and ultrasonic treatment was performed under condition C. [Experimental Example 31] The electrode to be treated was positive electrode B, UV treatment was not performed, and ultrasonic treatment was performed under condition D. [Experimental Examples 32-35] The electrode to be treated was positive electrode B, UV treatment was performed under condition B, and ultrasonic treatment was performed under condition D.

[0052] [Results and Discussion] Tables 1 and 2 summarize the electrodes to be treated, UV treatment conditions, contact angle, ultrasonic treatment conditions, and asphalt peeling rate. First, we examined Experimental Examples 1 to 28 using positive electrode A. In the experimental examples without UV treatment (Experimental Examples 1 and 21), the contact angle of the electrode asphalt surface before ultrasonic treatment was 128.7°, suggesting that the surface was hydrophobic. In the experimental examples where ultrasonic treatment was performed without UV treatment, the asphalt peeling rate was 11.2% in Experimental Example 1 and 9.2% in Experimental Example 21. In the experimental examples with UV treatment (Experimental Examples 2 to 20 and 22 to 28), the contact angle of the electrode asphalt surface before ultrasonic treatment was smaller than 128.7° for the no-UV treatment example, and it decreased with longer UV treatment times, suggesting that the electrode asphalt became hydrophilic due to UV treatment. In the experimental cases where ultrasonic treatment was performed after UV treatment, the asphalt detachment rate was higher in experimental cases 2-20, which were ultrasonically treated under the same conditions as experimental case 1, than in experimental case 1 (11.2%), and higher in experimental cases 22-28, which were ultrasonically treated under the same conditions as experimental case 21, than in experimental case 21 (9.2%). Furthermore, a tendency was observed for the asphalt detachment rate to increase with decreasing contact angle. From this, it was inferred that the electrode asphalt became hydrophilic due to UV treatment, leading to an increase in the asphalt detachment rate.

[0053] In experimental examples 2-8, where UV treatment was performed at a wavelength of 172 nm, and experimental examples 9-14, where UV treatment was performed at wavelengths of 184.9 nm + 253.7 nm, a tendency for higher peeling effect was observed compared to experimental examples 15-20, where UV treatment was performed at a wavelength of 365 nm. In particular, experimental examples 9-14, where UV treatment was performed at wavelengths of 184.9 nm + 253.7 nm, showed a tendency for even higher peeling effect. The 184.9 nm + 253.7 nm wavelength resulted in a higher asphalt peeling rate with shorter irradiation times than the 172 nm wavelength, which was presumed to be due to the higher UV intensity. Since shorter wavelengths have greater light energy and generate oxygen radicals more easily, it was presumed that hydrophilization and improved peeling efficiency were achieved at a wavelength of 172 nm even with low UV intensity and low integrated light amount.

[0054] Next, we examined experimental examples 29-35 using positive electrode B. In the experimental examples without UV treatment (experimental examples 29 and 31), the contact angle of the electrode composite surface before ultrasonic treatment was 114.8°, suggesting that it was a hydrophobic surface. In the experimental examples where ultrasonic treatment was performed without UV treatment, the adhesion rate of the electrode composite was 54.6% in experimental example 29 and 30.9% in experimental example 31. In the experimental examples with UV treatment (experimental examples 30 and 32-35), the contact angle of the electrode composite before ultrasonic treatment was smaller than 114.8° for the example without UV treatment, and it decreased with longer UV treatment time, suggesting that the electrode composite became hydrophilic due to UV treatment. In the experimental examples where ultrasonic treatment was performed after UV treatment, the adhesion rate of the electrode composite was higher in experimental example 30, which was ultrasonically treated under the same conditions as experimental example 29, than in experimental example 29 (54.6%), and higher in experimental examples 32-35, which were ultrasonically treated under the same conditions as experimental example 31, than in experimental example 31 (30.9%). Furthermore, it was observed that the smaller the contact angle, the higher the asphalt mixture peeling rate tended to be. From this, it was inferred that, similar to the case of positive electrode B, the electrode asphalt mixture became hydrophilic due to UV treatment, resulting in a higher asphalt mixture peeling rate.

[0055] Positive electrode B became hydrophilic in a shorter time than positive electrode A, and the asphalt mixture could be peeled off at high frequency and low power. This was presumed to be because, with positive electrode B, the asphalt mixture layer was thinner, and UV light caused hydrophilicization not only on the outermost surface of the asphalt mixture layer but also inside the asphalt mixture.

[0056] In experimental examples 2-8 and 30, where UV treatment was performed at a wavelength of 172 nm, and experimental examples 9-14, 22-28, and 32-35, where UV treatment was performed at wavelengths of 184.9 nm + 253.7 nm, the asphalt delamination rate was 30% or more when UV irradiation was 3 minutes or more, 50% when UV irradiation was 5 minutes or more, 80% or more when UV irradiation was 10 minutes or more, and 90% or more when UV irradiation was 20 minutes or more, indicating that the asphalt delamination rate can be increased by increasing the UV irradiation time. Furthermore, the asphalt delamination rate was 30% or more when the contact angle was 100° or less, 50% or more when the contact angle was 90° or less, 80% or more when the contact angle was 80° or less, and 90% or more when the contact angle was 60° or less, indicating that the asphalt delamination rate can be increased by decreasing the contact angle (increasing hydrophilicity).

[0057] [Table 1]

[0058] [Table 2] [Industrial applicability]

[0059] This disclosure is applicable to the field of the battery industry. [Explanation of symbols]

[0060] 10 Separation device, 15 Control unit, 20 UV unit, 21 Lamp, 22 Processing chamber, 30 Ultrasonic unit, 32 Processing container, 34 Inner tank, 35 Mounting platform, 36 Outer tank, 38 Transducer, 40 Oscillator, 42 Treated water, 43 Treated water containing composite material, 46 Ultrasonic propagation medium, 50, 50A Electrode to be treated, 52 Current collector, 54, 54A Electrode composite material.

Claims

1. A UV step is performed by irradiating an electrode to be treated, which comprises a current collector and an electrode composite material formed on the current collector, with ultraviolet light. An ultrasonic process is performed on the electrode to be treated after ultraviolet irradiation, while sweeping the ultrasonic frequency in the treatment water, to separate the current collector and the electrode composite material. A separation method that includes [this].

2. The separation method according to claim 1, wherein the UV step is performed by irradiating with ultraviolet light with a wavelength of 260 nm or less.

3. The separation method according to claim 1 or 2, wherein the UV step is performed under conditions that the contact angle between the electrode mixture surface and the treated water is 90° or less.

4. The separation method according to claim 1 or 2, wherein the UV step is performed for a period of 30 minutes or less.

5. In the aforementioned UV process, the illuminance was 50 mW / cm². 2 The separation method according to claim 1 or 2, wherein the ultraviolet irradiation is performed with the following ultraviolet light.

6. The separation method according to claim 1 or 2, wherein the ultrasonic step 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 claim 1 or 2, wherein the ultrasonic process is performed within a range of 10 minutes or less.

8. The separation method according to claim 1 or 2, wherein the electrode to be processed includes a solvent-based binder.

9. 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 claim 1 or 2.

10. A UV unit that irradiates an electrode to be treated, which comprises a current collector and an electrode composite material formed on the current collector, An ultrasonic unit that performs ultrasonic treatment on the electrode to be treated after ultraviolet irradiation in treated water to separate the current collector and the electrode composite material, A control unit that controls the ultrasonic unit to perform the ultrasonic processing while sweeping the ultrasonic frequency, A separation device equipped with this device.

Images