Separation method and separation device

Abstract

To efficiently and highly accurately separate a current collector from an electrode mixture.SOLUTION: A separation method includes a separation step of performing ultrasonic treatment on a treatment object electrode 50 having a current collector 52 and an electrode mixture 54 while sweeping frequencies of the ultrasonic wave in water (treatment liquid 32) and separating the current collector 52 from the electrode mixture 54. The separation device 10 includes: a separation unit 60 which performs the ultrasonic treatment underwater on the treatment object electrode 50 and separates the current collector 52 from the electrode mixture 54; and a control unit 15 which controls the separation unit 60 so as to perform the ultrasonic treatment while sweeping the frequencies of the ultrasonic wave.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a separation method and a separation device. [Background technology]

[0002] Conventional methods for separating the current collector and the electrode composite in battery recycling include, for example, immersing small pieces of the battery in a polar solvent such as water, alcohol, or ketone, and mechanically agitating them by stirring or ultrasonic treatment for about 30 minutes to about 5 hours (Patent Document 1), or using an ultrasonic electrode with a power density of 50 W / cm on the front surface. 2 Proposed methods include ultrasonically treating an electrode sheet under the above conditions (Patent Document 2), immersing the positive electrode in NMP at 50°C for 6 hours followed by ultrasonic treatment and scraping (Non-Patent Document 1), using NMP as a cleaning solution for the positive electrode and ultrasonically treating it for 90 minutes at 70°C and 240 W (Non-Patent Document 2), and crushing the electrode into pieces of 2 to 12 mm and ultrasonically treating it at 40 Hz and 100 W (Non-Patent Document 3). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6828214 [Patent Document 2] International Publication No. 2021 / 152302 Brochure [Non-patent literature]

[0004] [Non-Patent Document 1] H. Gao et al., ACS Appl. Mater. Interfaces 12, 2020, 51546-51554. [Non-patent document 2] L.-P. He et al., Waste Management 46, 2015, 523-528. [Non-patent document 3] J. Li et al., Chemosphere 77, 2009, 1132-1136. Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the above-described methods, even if the electrode mixture can be removed from the current collector, the current collector may be damaged, or even if damage to the current collector is suppressed, the electrode mixture may remain on the current collector. As a result, current collector components may be mixed into the separated electrode mixture, or electrode mixture components may be mixed into the separated current collector. Furthermore, these methods require long processing times or pretreatment such as crushing, resulting in low processing efficiency.

[0006] The present disclosure has been made to solve such problems, and a main object of the present disclosure is to separate the current collector and the electrode mixture efficiently and with high precision. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the inventors discovered that when an electrode is subjected to ultrasonic treatment in water while sweeping the frequency of ultrasonic waves, the current collector and the electrode composite can be separated efficiently and with high precision, and have completed the present disclosure.

[0008] That is, the separation method of the present disclosure includes: The method includes a separation step in which an electrode to be treated, which comprises a current collector and an electrode composite formed on the current collector, is subjected to ultrasonic treatment in water while sweeping the frequency of ultrasonic waves, thereby separating the current collector from the electrode composite.

[0009] The separation device of the present disclosure also includes: a separation unit that performs ultrasonic treatment in water on a treatment target electrode including a current collector and an electrode composite material formed on the current collector to separate the current collector and the electrode composite material; a control unit that controls the separation unit so that the ultrasonic processing is performed while sweeping the frequency of the ultrasonic waves; It is equipped with the following. [Effects of the Invention]

[0010] The separation method and separation device disclosed herein can efficiently and accurately separate the current collector and electrode composite. The reason for this effect is presumed to be as follows: This separation method and separation device utilizes the physical action of ultrasonic cavitation rather than the chemical action of an organic solvent or aqueous solution. Therefore, the current collector and electrode composite can be separated using water without using an organic solvent. Furthermore, water has a high surface tension and is more likely to generate a cavitation effect than organic solvents such as NMP, allowing for efficient separation of the current collector and electrode composite. Furthermore, ultrasonic treatment is performed in water while sweeping the ultrasonic frequency, resulting in a favorable energy distribution, which reduces damage to the current collector and residual electrode composite, allowing for highly accurate separation of the current collector and electrode composite. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is an explanatory diagram of a sweep and a sweep cycle. [Figure 2] An explanatory diagram of sweep width. [Figure 3] FIG. 1 is an explanatory diagram showing an outline of the configuration of a separation device 10. [Figure 4] FIG. 2 is an explanatory diagram showing the state of the ultrasonic device 20 before ultrasonic treatment. [Figure 5] FIG. 10 is an explanatory diagram showing the state of the ultrasonic device 20 after ultrasonic processing. [Figure 6] Photograph of the appearance of the electrode (collecting foil) after ultrasonic treatment. [Figure 7] Photograph of the appearance of the electrode (collecting foil) after ultrasonic treatment. [Figure 8] 10 is a flowchart showing an example of a separation method. [Figure 9] Photographs of the appearance of the electrode after ultrasonic treatment after each waiting time. [Figure 10] 10 is a graph showing the relationship between waiting time and mix removal rate. [Figure 11] 1 is a graph showing the relationship between the pH of water after ultrasonic treatment and the mixture removal rate. [Figure 12] 1 is a graph showing the relationship between the amount of eluted Li and the composite removal rate. [Figure 13] 1 is a graph showing the relationship between the amount of Al elution and the composite removal rate. [Figure 14] 1 is a graph showing the relationship between the mixture removal rate and the amount of Al in the mixture powder. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Separation method] The separation method of the present disclosure includes a separation step of subjecting the electrode to ultrasonic treatment to separate the current collector and the electrode mixture.

[0013] (electrode to be treated) The electrode to be treated comprises a current collector and an electrode composite formed on the current collector. The electrode to be treated is an electrode of an electricity storage device such as an ion secondary battery such as a lithium ion secondary battery, an electric double layer capacitor, a hybrid capacitor, or a pseudo-electric double layer capacitor, and may be removed from a used electricity storage device or a deteriorated electricity storage device. The electrode to be treated may be a positive electrode, a negative electrode, or a bipolar electrode with a positive electrode composite formed on one side and a negative electrode composite formed on the other side. The electrode to be treated may be an unshredded electrode removed from the electricity storage device, for example, an electrode having an area of ​​10 cm. 2 It can be more than 30cm 2 The above may also be used.

[0014] Examples of materials for the current collector include aluminum, copper, titanium, stainless steel, nickel, iron, baked carbon, conductive polymers, and conductive glass. When the electrode to be treated is a positive electrode, the current collector preferably contains aluminum. Examples of the shape of the current collector include foil, film, sheet, net, punched or expanded, lath, porous, foamed, and fibrous formed bodies. The thickness of the current collector is, for example, 1 to 500 μm.

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

[0016] Examples of the electrode active material contained in the electrode composite material include transition metal sulfides such as TiS2, TiS3, MoS3, FeS2, and lithium manganese composite oxides with a basic composition formula of Li (1-x) MnO2 (0 < x < 1, etc., the same below), Li (1-x) Mn2O4, etc., lithium cobalt composite oxides with a basic composition formula of Li (1-x) CoO2, etc., lithium nickel composite oxides with a basic composition formula of Li (1-x) NiO2, etc., and a basic composition formula of Li (1-x) Ni a Co b Mn cExamples of active materials used in the positive electrodes of lithium-ion secondary batteries include lithium-nickel-cobalt-manganese composite oxides with a basic formula such as LiV2O3, transition metal oxides with a basic formula such as V2O5, and lithium iron phosphate. The term "basic formula" refers to materials that may contain other elements such as Al and Mg. Examples of electrode active materials include active materials used in the positive and / or negative electrodes of capacitors and lithium-ion capacitors, such as activated carbons, cokes, glassy carbons, graphites, non-graphitizable carbons, pyrolytic carbons, carbon fibers, carbon nanotubes, and polyacenes. Examples of electrode active materials include inorganic compounds such as lithium alloys and tin compounds, carbonaceous materials capable of absorbing and releasing lithium ions, composite oxides containing multiple elements, and conductive polymers. 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 contained in the electrode mixture 54 include graphite such as natural graphite (scale graphite, flake graphite) and artificial graphite, acetylene black, carbon black, ketjen black, carbon whiskers, needle coke, carbon fibers, and metals (copper, nickel, aluminum, silver, gold, etc.).

[0017] The binder contained in the electrode mixture serves to bind the active material particles and the conductive material particles together. It may be an organic binder dissolved in an organic solvent, an aqueous binder dissolved in an aqueous solvent, or a mixture of these. Examples of organic binders include fluorine-containing resins such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluororubber; thermoplastic resins such as polypropylene and polyethylene; ethylene propylene diene monomer (EPDM) rubber; sulfonated EPDM rubber; and natural butyl rubber (NBR). Examples of aqueous binders include polyvinyl alcohol (PVA), styrene butadiene copolymer (SBR), and polyethylene oxide (PEO), and may also contain carboxymethyl cellulose (CMC). 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. Examples of aqueous solvents include water and various aqueous solutions. The conductive material contained in the electrode mixture can be, for example, one or a mixture of two or more of graphite, such as natural graphite (scale graphite, flake graphite) and artificial graphite, acetylene black, carbon black, ketjen black, carbon whisker, needle coke, carbon fiber, and metals (copper, nickel, aluminum, silver, gold, etc.). Among these, carbon black and acetylene black are preferred as the conductive material from the viewpoints of electronic conductivity and coatability.

[0018] (separation process) In the separation process, the electrode to be treated is subjected to ultrasonic treatment in water (i.e., the electrode to be treated is immersed in water) while sweeping the ultrasonic frequency to separate the current collector and the electrode composite. Sweeping the frequency means, for example, periodically changing the frequency as shown in Figures 1 and 2.

[0019] In the separation process, the frequency of the ultrasonic waves may be periodically changed so as to reciprocate between a maximum frequency Fmax and a minimum frequency Fmin, centered on a fundamental frequency F0 (see FIGS. 1 and 2). The fundamental frequency F0 is preferably 40 kHz or more and 240 kHz or less, and more preferably 80 kHz or more and 200 kHz or less.

[0020] In the separation process, when the sweep width is defined as the frequency fluctuation range centered on the fundamental frequency F0 (see FIG. 2), the sweep width may be set to within ±5 kHz. That is, Fmax-F0≦+5 kHz, Fmin-F0≧−5 kHz. The sweep width may be set to within ±3 kHz or ±1 kHz.

[0021] In the separation process, 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 (or 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) (see FIG. 1), and the number of sweep cycles per second is defined as the sweep rate. The sweep rate may be 500 sweep cycles / second or more, 700 sweep cycles / second or more, or 1000 sweep cycles / second or more, or 2000 sweep cycles / second or less.

[0022] In the separation step, ultrasonic treatment is preferably carried out for 30 minutes or less, more preferably for 10 minutes or less, even more preferably for 300 seconds or less, and even more preferably for 180 seconds or less. In the separation step, ultrasonic treatment may be carried out for 1 second or more, 5 seconds or more, or 15 seconds or more.

[0023] In the separation process, the contact area between the current collector and the electrode mixture is A [cm] 2 When the ultrasonic output (oscillator output) is B [W], the output density (power density) expressed as B / A is 30 W / cm 2It is preferable to perform ultrasonic treatment so that the power density B / A is 10 W / cm 2 It is preferable that the power consumption is 5 W / cm or less. 2 The power density B / A may be 0.1 W / cm or less. 2 More than 0.5W / cm 2 It may be more than that.

[0024] In the separation step, ultrasonic treatment is preferably performed in a non-heated environment. For example, ultrasonic treatment may be performed in a temperature range of 0°C to 30°C, or in a temperature range of 15°C to 25°C.

[0025] By carrying out the separation process 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 water or precipitates. Thus, after the ultrasonic treatment, the current collector and the electrode mixture are separated, and the current collector and mixture-containing water containing the electrode mixture are obtained.

[0026] The proportion of the current collector component (current collector component) contained in the electrode mixture separated in the separation step is preferably less than 0.18%, preferably less than 0.15%, and more preferably less than 0.1%. Furthermore, the proportion of the electrode mixture component (electrode mixture component) contained in the current collector separated in the separation step is preferably less than 0.36%, preferably less than 0.3%, and more preferably less than 0.2%. The "proportion of the current collector component contained in the electrode mixture" may be a value determined, for example, as follows: First, water is removed from the mixture-containing water obtained in the separation step to obtain an electrode mixture. The weight of the current collector component in the obtained electrode mixture is analyzed by inductively coupled plasma atomic emission spectroscopy (ICP). Then, the weight ratio of the current collector component to the weight of the electrode mixture analyzed is determined, and this weight ratio is defined as the proportion of the current collector component contained in the electrode mixture. The "proportion of the electrode mixture component contained in the current collector" may be a value determined, for example, as follows: First, the electrode (current collector) after ultrasonic treatment is removed, rinsed, and dried. The electrode mixture components of the rinsed and dried electrode are analyzed by ICP to determine the weight ratio of the electrode mixture components to the weight of the analyzed electrode, and this weight ratio is used as the ratio of the electrode mixture components contained in the current collector. Alternatively, the electrode mixture components of the rinsed and dried electrode are analyzed by the fundamental parameter method (FP method) of X-ray fluorescence analysis (XRF), and this weight ratio is used as the ratio of the electrode mixture components contained in the current collector. Note that the ratio of the electrode mixture components contained in the current collector may be the ratio of the active material components contained in the current collector, or, if the active material contains a transition metal, the ratio of the transition metal contained in the current collector (provided that the transition metal is contained in the active material). Transition metals may form alloys with the current collector components when the current collector (e.g., Al) is remelted, so it is desirable for as little of them to remain on the current collector.

[0027] In the separation step, it is preferable to increase the removal rate of the electrode composite from the current collector (also referred to as composite removal rate). This composite removal rate is, for example, preferably 90% or more, more preferably 97% or more, and even more preferably 99% or more. In the separation step, it is preferable to reduce the pH of the water after ultrasonic treatment. Components of the electrode to be treated may leach into the water, increasing the pH of the water. The smaller this increase, the higher the composite removal rate. This pH is, for example, preferably 11.5 or less, more preferably less than 11.4, and even more preferably less than 11.2. This pH may be, for example, 6 or more, 7 or more, or 10 or more. In the separation step, it is preferable to reduce the concentration of alkali metal components contained in the water after ultrasonic treatment. If alkali metal components are contained in the active material of the electrode to be treated, the alkali metal components may leach into the water after ultrasonic treatment. The lower the concentration of such alkali metal components, the higher the composite removal rate. The concentration of this alkali metal component is preferably 37.5 mg / L or less, more preferably less than 33 mg / L, and even more preferably less than 32 mg / L. In this separation step, it is preferable to reduce the amount of dissolution in water per weight of the current collector. The lower the amount of dissolution of the current collector in water, the higher the composite removal rate. The amount of dissolution of the current collector in water is preferably 1.1% or less, more preferably less than 1.0%, and even more preferably less than 0.9%. In the separation step, it is preferable to shorten the waiting time for placing the electrode to be treated in water before ultrasonic treatment. The shorter the waiting time, the more suppressed the elution of components contained in the electrode to be treated into water, thereby suppressing reactions between the eluted components and the electrode composite or current collector, and thereby increasing the composite removal rate. This waiting time is, for example, preferably 30 minutes or less, more preferably less than 5 minutes, and even more preferably less than 3 minutes.

[0028] In the separation step, it is preferable to reduce the weight ratio of the current collector component contained in the separated electrode mixture. This weight ratio is, for example, preferably 0.18% or less, more preferably 0.15% or less, and even less than 0.1%. moreoverIt is preferable. Note that the higher the composite removal rate described above, the smaller this weight ratio tends to be. Therefore, also from the viewpoint of reducing this weight ratio, in the separation step, it is preferable to reduce the pH described above, it is preferable to reduce the concentration of alkali metal components contained in the water after the ultrasonic treatment described above, it is preferable to reduce the amount of the current collector dissolved in water described above, and it is preferable to shorten the waiting time described above.

[0029] Before the separation step, a removal step of removing the electrode from the electricity storage device may be performed. The electrode removed in the removal step may be left as is without being shredded, or may be cut into pieces with an area of ​​10 cm. 2 or more, area 30cm 2 It may be cut into the above-mentioned shapes and used as the electrode to be treated.

[0030] After the separation step, a current collector treatment step may be performed in which the current collector separated in the separation step is rinsed and dried. The current collector may be rinsed while a rinse liquid is flowing, or by immersing the current collector in the rinse liquid. The rinse liquid is preferably water. The current collector may be dried by blow drying, heat drying, vacuum drying, barrel drying, spin drying, suction drying, infrared drying, or a combination of these methods.

[0031] After the separation step, a composite treatment step may be performed in which the electrode composite is filtered from the composite-containing water obtained in the separation step and dried. In the composite treatment step, the electrode composite may be rinsed during or after filtration. The rinsing liquid is preferably water. The electrode composite may be dried by blow drying, heat drying, vacuum drying, barrel drying, spin drying, suction drying, infrared drying, or a combination thereof. In the composite treatment step, instead of filtering the electrode composite, the electrode composite may be separated from the composite-containing water by a solid-liquid separation method such as centrifugation or evaporation to dryness.

[0032] The separation step, current collector treatment step, and composite treatment step may be performed in a batch system or a continuous system. When the separation step or current collector treatment step is performed in a continuous system, a roll-to-roll system may be adopted. When the separation step is performed in a roll-to-roll system, the electrodes removed in the removal step may be sequentially wound into a roll, and this may be used as the electrode to be treated.

[0033] In addition, since a current collector and an electrode mixture are obtained by this separation method, this separation method is also a method for producing a current collector and a method for producing an electrode mixture.

[0034] [Separation device] The separation device of the present disclosure includes a separation unit that ultrasonically treats an electrode to be treated to separate it into a current collector and an electrode composite, and a control unit that controls the separation unit. This separation device may perform the separation method described above, and the configurations and conditions described for the separation method may be applied. This separation device includes a carry-in unit that carries the electrode to be treated into the separation unit, and an unloading unit that unloads at least one of the current collector and the electrode composite separated in the separation unit from the separation unit, and the control unit may control the separation unit, the carry-in unit, and the unloading unit so that the ultrasonic treatment is performed batchwise or continuously.

[0035] Hereinafter, a separation device 10 will be described as an example of a separation device. FIG. 3 is an explanatory diagram showing an outline of the configuration of the separation device 10. The separation device 10 includes a separation section 60, a carry-in section 70, a current collector discharge section 80 and a composite discharge section 90 as discharge sections, and a control section 15. The separation device 10 performs ultrasonic treatment on a treatment target electrode 50 including a current collector 52 and an electrode composite 54, thereby separating the current collector 52 from the electrode composite 54. The treatment target electrode 50, the current collector 52, and the electrode composite 54 may be the same as the treatment target electrode, the current collector, and the electrode composite described in the separation method, respectively.

[0036] The separation unit 60 includes an ultrasonic device 20 and a pipe 62 that supplies water as the processing liquid 32 to the processing container 22 of the ultrasonic device 20. The pipe 62 is provided with a valve 62a, which allows adjustment of whether or not the processing liquid 32 is supplied to the processing container 22 and the amount of the supply.

[0037] The ultrasonic device 20 performs ultrasonic treatment on the electrode 50 to be treated in water. Figures 4 and 5 show the ultrasonic device 20 before and after ultrasonic treatment. The ultrasonic device 20 includes a treatment container 22 that contains the electrode 50 to be treated and the treatment liquid 32, a vibrator 28 that is arranged to be in contact with the treatment container 22, and an oscillator 30 that supplies an electric signal to the vibrator 28 to cause the vibrator 28 to oscillate. Water is used as the treatment liquid 32. The water may be tap water, distilled water, ion-exchanged water, or the like. The ultrasonic device 20 contains water as the treatment liquid 32 in the treatment container 22, and the electrode 50 to be treated is immersed in the treatment liquid 32 (see Figure 4). 30 From the oscillator 28 Power is supplied to the transducer 28 The ultrasonic wave is oscillated to perform ultrasonic treatment on the electrode 50 to be treated. This ultrasonic treatment separates the current collector 52 and the electrode composite 54 of the electrode 50 to be treated, and a composite-containing treatment liquid 33 (composite-containing water) containing the current collector 52 and the electrode composite 54 is obtained (see FIG. 5 ). Note that the treatment container 22 here includes an inner tank 24 in which the electrode 50 to be treated is accommodated, a mounting stand 25 on which the inner tank 24 is placed, and an outer tank 26 in which the inner tank 24 and the mounting stand 25 are accommodated. The inner tank 24 accommodates the treatment liquid 32, and the outer tank 26 accommodates an ultrasonic propagation medium 36. The ultrasonic propagation medium 36 is, for example, water, and serves to propagate ultrasonic waves together with the treatment liquid 32.

[0038] The oscillator 30 of the ultrasonic device 20 has a sweep function. The sweep function is a function of periodically changing the frequency, as shown in Figures 1 and 2, for example. The ultrasonic device 20 is configured so that, by using the sweep function of the oscillator 30, the frequency of the ultrasonic waves generated from the transducer 28 can be swept (periodically changed).

[0039] The carry-in section 70 is equipped with a conveyor 72 that transports the target electrode 50 to the separation section 60. The carry-in section 70 may also be equipped with an unloading section (not shown) that disassembles the battery and unloads the electrode that will become the target electrode 50. The unloading section may also be equipped with a discharging section that discharges the battery before disassembling it. The discharging section may forcibly discharge the battery using an external power source. The unloading section may also be equipped with an inactivation section that inactivates the battery. The inactivation section may inactivate the battery by heat treatment, or may inactivate the battery by supplying an inactivating agent to the inside of the battery. The carry-in section 70 may also be equipped with a pre-treatment section (not shown) that processes the electrode unloaded in the unloading section so that it is suitable for ultrasonic treatment in the separation section 60. The pre-treatment section may wash or dry the electrode unloaded in the unloading section. The pre-treatment section may also be equipped with a pre-treatment section that processes the electrode unloaded in the unloading section into a 10 cm area. 2 More than 30cm 2 The electrodes may be cut as described above, or the electrodes removed in the removal unit may be sequentially wound into a roll. Note that the carry-in unit 70 only needs to be configured to be able to carry the target electrodes 50 into the separation unit 60, and may be equipped with, for example, a transport means other than the conveyor 72. The removal unit and the pre-treatment unit may also be provided separately from the carry-in unit 70.

[0040] The current collector discharge unit 80 includes a robot arm 82 that removes the current collector 52 separated in the separation unit 60 from the treatment vessel 22, and a conveyor 84 that transports the current collector 52 removed by the robot arm 82. The current collector discharge unit 80 also includes a rinsing device 86 that rinses the current collector 52 transported by the conveyor 84, and a drying device 88 that dries the current collector 52 transported by the conveyor 84. The rinsing device 86 may be configured to perform rinsing while a rinsing liquid is flowing as shown in FIG. 3, or may be configured to perform rinsing by immersion in the rinsing liquid. The rinsing liquid is preferably water. The drying device 88 may be configured to perform drying by blow drying, heat drying, vacuum drying, barrel drying, spin drying, suction drying, infrared drying, or a combination of these. It should be noted that the current collector discharge section 80 only needs to be configured to be able to discharge the current collector 52 from the separation section 60, and for example, either one of the robot arm 82 or the conveyor 84 may be omitted, or a transport means other than the robot arm 82 or the conveyor 84 may be provided. Furthermore, the rinsing device 86 and the drying device 88 may be provided separately from the current collector discharge section 80, or may be omitted.

[0041] The composite discharge section 90 includes a pipe 92 for discharging the composite-containing treatment liquid 33 obtained in the separation section 60 from the treatment vessel 22, a filtration device 94 for filtering the electrode mixture 54 from the composite-containing treatment liquid 33, a conveyor 96 for transporting the electrode mixture 54 filtered by the filtration device 94, and a drying device 98 for drying the electrode mixture 54 filtered by the filtration device 94. The pipe 92 is connected near the bottom of the treatment vessel 22. A valve 92a is provided in the pipe 92 so that the storage and discharge of the treatment liquid 32 and the composite-containing treatment liquid 33 in the treatment vessel 22 can be adjusted. The drying device 98 may be configured to perform drying by blow drying, heat drying, vacuum drying, barrel drying, spin drying, suction drying, infrared drying, or a combination of these. The composite discharge section 90 may also include a rinsing device for rinsing the electrode mixture 54. The rinsing device may be configured to supply a rinsing liquid to the filtration device 94 to perform rinsing while filtering, or may be configured to separately rinse the electrode mixture 54 after filtering using the rinsing liquid. The rinsing liquid is preferably water. The composite material discharge unit 90 may be configured to be able to discharge the electrode mixture 54 from the separation unit 60, and either one of the piping 92 and the conveyor 96 may be omitted, or a transport means other than the piping 92 or the conveyor 96 may be provided. The filtration device 94, the drying device 98, the rinsing device, etc. may be provided separately from the composite material discharge unit 90, or may be omitted. The filtration device 94 may be replaced with a solid-liquid separation device such as a centrifugal separator or an evaporator-to-dryness device.

[0042] The control unit 15 is configured as a microprocessor centered on a CPU, and in addition to the CPU, includes a storage device, an input / output port, and the like (not shown). The control unit 15 is connected to the separation unit 60 (specifically, the oscillator 30 and the valve 62a of the piping 62), the carry-in unit 70 (specifically, the conveyor 72), the current collector discharge unit 80 (specifically, the robot arm 82, the conveyor 84, the rinsing device 86, and the drying device 88), and the composite discharge unit 90 (specifically, the valve 92a of the piping 92, the filtering device 94, the conveyor 96, and the drying device 98). The control unit 15 performs ultrasonic treatment while sweeping the frequency of the ultrasonic waves, and controls the separation unit 60, the carry-in unit 70, the current collector discharge unit 80, and the composite discharge unit 90 so that the ultrasonic treatment is performed batchwise. The ultrasonic treatment conditions may be the same as those of the separation method described above (particularly, the separation step). For convenience of illustration, FIG. 3 shows only the connection between the control unit 15 and the oscillator 30, and does not show other connections.

[0043] An example of the operation of the separation device 10 will be described. When a command to start the separation process is input to the control unit 15, the control unit 15 first controls the conveyor 72 to transport the target electrode 50 placed on the conveyor 72 into the treatment container 22 of the separation unit 60, and controls the valve 62a of the pipe 62 to supply a predetermined amount of water as the treatment liquid 32 to the treatment container 22. After the target electrode 50 has been transported and the treatment liquid 32 has been supplied, the control unit 15 controls the oscillator 30 to supply an electrical signal to the vibrator 28, causing the vibrator 28 to oscillate. This results in ultrasonic treatment of the target electrode 50 in the treatment liquid 32. During ultrasonic treatment, the control unit 15 uses the sweep function of the oscillator 30 to control the oscillator 30 to sweep the frequency under the following conditions: a fundamental frequency F0 of 40 kHz or more and 240 kHz or less, a sweep width of ±5 kHz or less, and a sweep rate of 500 sweep cycles / second or more. Furthermore, the control unit 15 may set the output density B / A to 30 W / cm 2The control unit 15 controls the oscillator 30 to output a power equal to or less than the value specified by the ultrasonic treatment. The control unit 15 also controls the oscillator 30 to perform the ultrasonic treatment for a predetermined time, for example, in a range of 1 second to 30 minutes. This ultrasonic treatment separates the current collector 52 and the electrode composite 54 of the electrode 50 to obtain a composite-containing treatment solution 33 containing the current collector 52 and the electrode composite 54. The control unit 15 then controls the robot arm 82 to remove the current collector 52 from the treatment container 22 and place it on the conveyor 84, and controls the conveyor 84 to transport the current collector 52. While the current collector 52 is being transported, the control unit 15 controls the rinsing device 86 to rinse the current collector 52, and then controls the drying device 88 to dry the current collector 52. In parallel with the removal of the current collector 52, the control unit 15 controls the valve 92a of the pipe 92 to discharge the composite-containing treatment liquid 33 from the treatment container 22 and supply it to the filtration device 94, which then filters the electrode mixture 54 from the composite-containing treatment liquid 33. After the electrode mixture 54 has been filtered out, the control unit 15 controls the filtration device 94 to discharge the electrode mixture 54 onto the conveyor 96, and controls the conveyor 96 to transport the electrode mixture 54. While the electrode mixture 54 is being transported, the control unit 15 controls the drying device 98 to dry the electrode mixture 54. This completes the separation of the current collector 52 and the electrode mixture 54 of the electrode 50 to be treated. In the separation device 10, the ultrasonic treatment is performed batchwise by repeating this series of operations.

[0044] The separator 10 may be equipped with a pH detector that measures the pH of the water in the treatment vessel 22 and configured to perform the separation process so that the pH of the water does not exceed a predetermined value (e.g., 11.5). The separator 10 may be equipped with an alkali metal component detector that detects alkali metal components contained in the water in the treatment vessel 22 and configured to perform the separation process so that the concentration of alkali metal components contained in the water does not exceed a predetermined value (e.g., 37.5 mg / L). The separator 10 may be equipped with a current collector component detector that detects current collector components contained in the water in the treatment vessel 22 and configured to perform the separation process so that the amount of current collector components contained in the water does not exceed a predetermined value (e.g., 1.1%) per weight of the current collector. The separator 10 may be equipped with a standby time measurement unit that measures the above-mentioned standby time and configured to start the ultrasonic treatment within the predetermined standby time (e.g., within 30 minutes).

[0045] The separation method and separation device described above can efficiently and accurately separate the current collector and the electrode composite. The reason for this effect is presumed to be as follows: The separation method and separation device described above utilize a physical action utilizing the cavitation effect of ultrasound to separate the current collector and the electrode composite, allowing the current collector and the electrode composite to be separated using water. Furthermore, water has a high surface tension and is more likely to generate a cavitation effect than organic solvents, allowing the current collector and the electrode composite to be separated efficiently. Furthermore, ultrasonic treatment is performed in water while sweeping the ultrasonic frequency, resulting in a favorable energy distribution, suppressing damage to the current collector and the remaining electrode composite, and allowing the current collector and the electrode composite to be separated with high accuracy. Furthermore, the separation method and separation device described above utilize a physical action utilizing the cavitation effect of ultrasound, allowing the current collector and the electrode composite to be separated using water, regardless of whether the binder contained in the electrode composite is aqueous or organic. In addition, because water is used as the treatment liquid, the treatment liquid is relatively inexpensive, the treatment liquid can be easily removed from the separated current collector and electrode composite, and waste liquid is easily treated, resulting in a small environmental impact.Furthermore, because the current collector and electrode composite can be separated efficiently, the current collector and electrode composite can be separated with high precision even at high frequencies (low energy) such as 40 to 240 kHz (preferably 80 to 200 kHz), even when the electrode to be treated is relatively large, and even in a non-heated environment.

[0046] It goes without saying that the present disclosure is not limited to the above-described embodiments, and can be embodied in various forms as long as they fall within the technical scope of the present disclosure.

[0047] For example, in the above-described embodiment, the separation device 10 includes the separation unit 60, the carry-in unit 70, the current collector carry-out unit 80, and the composite material carry-out unit 90, but one or more of the carry-in unit 70, the current collector carry-out unit 80, and the composite material carry-out unit 90 may be omitted. Also, the separation unit 60 includes the ultrasonic device 20 and the piping 62, but the piping 62 may be omitted if the separation unit 60 is configured to perform ultrasonic treatment on the target electrode 50 in water.

[0048] In the above-described embodiment, the separation device 10 performs ultrasonic treatment in a batch manner, but ultrasonic treatment may also be performed in a continuous manner. In this case, the transport means of the carry-in unit 70 may be replaced by a delivery device that delivers the target electrode 50 wound in a roll. Furthermore, the transport means of the current collector discharge unit 80 may be replaced by a winding device that winds up the current collector 52, instead of the robot arm 82 and conveyor 84.

[0049] The present disclosure may be any of the following [1] to

[14] . [1] A separation method comprising: a separation step of subjecting a target electrode, which comprises a current collector and an electrode composite formed on the current collector, to ultrasonic treatment in water while sweeping ultrasonic frequencies to separate the current collector from the electrode composite. [2] The separation method according to [1], wherein in the separation step, the ultrasonic treatment is performed on the electrode to be treated, which includes the electrode mixture containing at least one of an organic binder and an aqueous binder. [3] The separation method according to [1] or [2], wherein in the separation step, the sweep is performed centered on a fundamental frequency of 80 kHz or more and 200 kHz or less. [4] The separation method according to any one of [1] to [3], wherein in the separation step, the sweep is performed with a sweep width within ±3 kHz around the fundamental frequency. [5] The separation method according to any one of [1] to [4], wherein in the separation step, the sweep is performed at a sweep rate of 500 sweep cycles / second or more. [6] The separation method according to any one of [1] to [5], wherein the ultrasonic treatment is carried out for 10 minutes or less in the separation step. [7] In the separation step, the contact area between the current collector and the electrode mixture is set to A [cm 2 ], and the output of the ultrasonic wave is B [W], the output density expressed as B / A is 10 W / cm 2The separation method according to any one of [1] to [6], wherein the ultrasonic treatment is carried out so that: [8] The separation method according to any one of [1] to [7], wherein a ratio of the current collector component in the electrode mixture separated in the separation step is less than 0.1%, and a ratio of the electrode mixture component in the current collector separated in the separation step is less than 0.2%. [9] The separation method according to any one of [1] to [8], wherein the ultrasonic treatment is carried out in a non-heated environment in the separation step.

[10] The separation method according to any one of [1] to [9], wherein the ultrasonic treatment is carried out in a batch system or a continuous system.

[11] The separation method according to any one of [1] to

[10] , a removal step of removing the electrode from the electricity storage device, In the separating step, the electrode removed in the removing step is used as the processing target electrode without being shredded, and the ultrasonic treatment is performed on the electrode.

[12] The separation method according to any one of [1] to

[11] , comprising at least one of a current collector treatment step of rinsing and drying the current collector separated in the separation step, and a composite treatment step of separating the electrode composite from composite-containing water containing the electrode composite separated in the separation step and drying the electrode composite.

[13] The separation method according to any one of [1] to

[12] , wherein the separation step is carried out so as to satisfy at least one of (1) to (6). (1) In the separation step, the pH of the water after the ultrasonic treatment is adjusted to 11.5 or less. (2) In the separation step, the concentration of alkali metal components contained in the water after the ultrasonic treatment is set to 37.5 mg / L or less. (3) In the separation step, the amount of the current collector dissolved in the water is set to 1.1% or less per weight of the current collector. (4) In the separation step, the waiting time for placing the electrode to be treated in the water before the ultrasonic treatment is set to 30 minutes or less. (5) In the separation step, the weight ratio of the current collector component contained in the separated electrode mixture is set to 0.18% or less. (6) In the separation step, the electrode mixture is removed from the current collector at a removal rate of 90% or more.

[14] a separation unit that performs ultrasonic treatment in water on a treatment target electrode including a current collector and an electrode composite material formed on the current collector to separate the current collector and the electrode composite material; a control unit that controls the separation unit so that the ultrasonic processing is performed while sweeping the frequency of the ultrasonic waves; A separation device comprising: [Example]

[0050] Examples of carrying out the separation method of the present disclosure are described below. Experimental Examples 1 to 14 and Experimental Example 19 correspond to Examples, Experimental Examples 15 to 18 correspond to Comparative Examples, and Experimental Examples 20 to 28 correspond to Examples.

[0051] 1. Experimental Examples 1-19 [Preparing the electrode to be treated] As electrodes to be treated, positive electrodes A to C and negative electrodes A to B shown below were prepared (see Table 1).

[0052] Positive electrode A is LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 A positive electrode composite containing 92 wt% O2 (NCM, manufactured by Toda Kogyo Kogyo), 5 wt% acetylene black (manufactured by Denka Co., Ltd.), and 3 wt% polyvinylidene fluoride (PVDF, manufactured by Kureha) was made into a paste using N-methylpyrrolidone (NMP), and this was applied to both sides of a 20 μm thick aluminum current collector foil.

[0053] Positive electrode B is LiNi 0.8 Co 0.15 Al 0.05A positive electrode composite containing 92 wt% O2 (NCA, manufactured by Toda Kogyo Co., Ltd.), 5 wt% acetylene black (manufactured by Denka Co., Ltd.), and 3 wt% polyvinylidene fluoride (PVDF, manufactured by Kureha) was made into a paste using NMP and coated on both sides of a 20 μm thick aluminum current collector foil.

[0054] Positive electrode C was prepared by forming a paste of a positive electrode composite containing 92 wt% LiFePO4 (a proprietary compound), 5 wt% acetylene black (manufactured by Denka Co., Ltd.), and 3 wt% polyvinylidene fluoride (PVDF, manufactured by Kureha) using NMP, and applying the paste to both sides of a 20 μm thick aluminum current collector foil.

[0055] Negative electrode A was prepared by mixing a negative electrode composite containing 98 wt% graphite (OMAC1.5s, manufactured by Osaka Gas Chemicals), 1 wt% carboxymethyl cellulose (CMC, manufactured by Daicel), and 1 wt% styrene-butadiene copolymer (SBR, manufactured by JSR) in water to form a paste, which was then applied to both sides of a 10 μm-thick copper current collector foil.

[0056] Negative electrode B was prepared by mixing a negative electrode composite containing 98 wt% graphite (SCMG-XR-s, manufactured by Showa Denko), 1 wt% carboxymethyl cellulose (CMC, manufactured by Daicel), and 1 wt% styrene-butadiene copolymer (SBR, manufactured by JSR) in water to form a paste, which was then applied to both sides of a 10 μm-thick copper current collector foil.

[0057] [Ultrasonic treatment] An ultrasonic device (Branson GCX-M-3FQ12, output power 500 W, outer tank capacity 20 L) was used for the ultrasonic treatments in Experimental Examples 1 to 19. Specifically, as shown in FIG. 4, water was placed in outer tank 26, 40 mL of treatment solution 32 was placed in glass container (inner tank 24), and electrode 50 to be treated was immersed therein. Ultrasonic waves were applied from transducer 28 below outer tank 26. When using the ultrasonic frequency sweep function, the sweep speed was set to 1000 sweep cycles / second. The power density was calculated by dividing the output power (500 W) of the ultrasonic device by the contact area between the current collecting foil and the electrode composite layer (here, electrode area × 2). The power density was adjusted by adjusting the electrode area.

[0058] In Experimental Example 1, a 40 mm × 100 mm positive electrode A was used as the electrode to be treated. The treatment liquid was water, the ultrasonic frequency (fundamental frequency F0) was 170 kHz, the sweep conditions (sweep width) were ±1 kHz, the treatment time was 60 seconds, and the power density was 6.3 W / cm. 2 It was decided.

[0059] In Experimental Example 2, a 40 mm × 100 mm negative electrode A was used as the electrode to be treated. The treatment liquid was water, the ultrasonic frequency was 170 kHz, the sweep conditions were ±1 kHz, the treatment time was 30 seconds, and the power density was 6.3 W / cm. 2 It was decided.

[0060] Experimental Example 3 was the same as Experimental Example 1 except that the ultrasonic frequency was 120 kHz. Experimental Example 4 was the same as Experimental Example 3 except that the treatment time was 30 seconds. Experimental Example 5 was the same as Experimental Example 3 except that the electrode size was 40 mm × 200 mm, and the power density was 3.1 W / cm 2 Experimental Example 6 was the same as Experimental Example 3 except that the electrode to be treated was positive electrode B. Experimental Example 7 was the same as Experimental Example 3 except that the electrode to be treated was positive electrode C.

[0061] Experimental Example 8 was the same as Experimental Example 2 except that the ultrasonic frequency was 120 kHz. Experimental Example 9 was the same as Experimental Example 8 except that the treatment time was 10 seconds. Experimental Example 10 was the same as Experimental Example 8 except that the electrode size was 40 mm × 200 m, and the power density was 3.1 W / cm 2 In Experimental Example 11, the treatment time was set to 60 seconds, and the electrode size was set to 40 mm × 715 mm, resulting in a power density of 0.9 W / cm 2 Experimental Example 12 was the same as Experimental Example 8 except that the electrode to be treated was negative electrode B.

[0062] Experimental Example 13 was the same as Experimental Example 1 except that the ultrasonic frequency was 80 kHz. Experimental Example 14 was the same as Experimental Example 2 except that the ultrasonic frequency was 80 kHz.

[0063] Experimental Example 15 was the same as Experimental Example 3 except that the sweep condition was changed to no sweep. Experimental Example 16 was the same as Experimental Example 8 except that the sweep condition was changed to no sweep.

[0064] Experimental Example 17 was the same as Experimental Example 3 except that the treatment liquid was NMP. Experimental Example 18 was the same as Experimental Example 17 except that the ultrasonic frequency was 40 kHz and the treatment time was 30 seconds.

[0065] Experimental Example 19 was the same as Experimental Example 1 except that the ultrasonic frequency was 40 kHz.

[0066] [Analysis of the ratio of current collecting foil components in the composite] For Experimental Examples 1 to 19, the proportion of the current collecting foil components in the composite was determined by inductively coupled plasma atomic emission spectroscopy (ICP). Specifically, first, the solution containing the composite powder after ultrasonic treatment (composite-containing treatment solution) was pressure filtered using a membrane filter (Merck Millpore JGWP 0.45 μm) while washing with pure water, and then dried at 50°C for 1 hour to obtain a composite powder. The weight of the current collecting foil components (aluminum or copper) in the composite powder was analyzed by ICP to determine the weight ratio of the current collecting foil components to the total weight of the composite powder. This was defined as the proportion of the current collecting foil components in the composite. A ratio of less than 0.1% was evaluated as "A (Excellent)," 0.1% to less than 0.18% as "B (Good)," and 0.18% or more as "F (Unacceptable)."

[0067] [Analysis of the proportion of composite components in current collecting foil] For Experimental Examples 1, 3 to 7, 13, 15, and 17 to 19 (positive electrodes), the proportion of composite components in the current collecting foil was determined by inductively coupled plasma atomic emission spectroscopy (ICP). Specifically, the electrodes were first removed from the ultrasonic treatment, rinsed with water, and then air-dried. For these electrodes, the weight of the composite components (transition metal components in the composite; Ni, Co, and Mn for positive electrode A) was determined by ICP, and the weight ratio of the composite components to the total electrode weight was calculated. This was defined as the proportion of the composite components in the current collecting foil. For Experimental Examples 2, 8 to 12, 14, and 16 (negative electrodes), the proportion of the composite components in the current collecting foil was determined by the fundamental parameter method (FP method) of X-ray fluorescence analysis (XRF). Specifically, the electrodes were first removed from the ultrasonic treatment, rinsed with water, and then air-dried. For these electrodes, the carbon content (weight ratio) was determined within a φ30 mm analysis range by the FP method of XRF. In the XRF FP method, the quantitative value is calculated by normalizing all detected elements to 100%. The amount of C on one side and in the surface layer is also calibrated. The amount of C determined in this way was used as the percentage of the composite component in the current collector foil. Less than 0.2% was then rated as "A (Excellent)," 0.2% to 0.36% as "B (Good)," and 0.36% or more as "F (Fail)."

[0068] [Results and Discussion] The ratios of the current collecting foil components in the composite and the ratios of the composite components in the current collecting foil for Experimental Examples 1 to 19 are summarized in Table 2. Photographs of the appearance of the electrodes (current collecting foils) after ultrasonic treatment for Experimental Examples 8, 16, 3, and 15 are shown in FIG. 6. Photographs of the appearance of the electrode (current collecting foil) after ultrasonic treatment for Experimental Example 11 are shown in FIG. 7.

[0069] As shown in Table 2, in Experimental Examples 1 to 14 and Experimental Example 19, in which water was used as the treatment liquid and ultrasonic treatment was performed using the sweep function, the evaluations of the ratio of the current collecting foil components in the composite and the ratio of the composite components in the current collecting foil were both A or B, demonstrating that the composite and the current collecting foil can be separated with high precision. It was also found that the composite and the current collecting foil can be separated with high precision by ultrasonic treatment for a short time of 60 seconds or less. In addition, it was found that the composite and the current collecting foil can be separated with high precision by ultrasonic treatment for a short time of 60 seconds or less. 2It was found that the composite and current collecting foil could be separated with high precision at the following low power density: Furthermore, although the binder for the positive electrode (PVDF) is organic and the binder for the negative electrode (SBR) is water-based, it was found that the composite and current collecting foil could be separated with high precision using ultrasonic treatment with water regardless of which binder was used.

[0070] In contrast to this, in Experimental Examples 15 and 16, in which water was used as the treatment liquid and ultrasonic treatment was performed without using the sweep function, a large amount of the composite material remained on the current collecting foil.

[0071] Furthermore, in Experimental Examples 17 and 18, in which NMP was used as the treatment solution and ultrasonic treatment was performed using the sweep function, a large amount of composite material remained on the current collecting foil. Because organic binders dissolve in NMP, it was expected that more composite material would be removed in Experimental Examples 17 and 18, in which NMP was used as the treatment solution, than in Experimental Examples 3 and 19, in which water was used as the treatment solution. However, in fact, more composite material was removed in Experimental Examples 17 and 18, in which the treatment solution was NMP, the cavitation effect of ultrasound was weaker. Furthermore, among Experimental Examples 17 and 18, Experimental Example 18, in which the ultrasonic frequency was 40 kHz, not only increased the proportion of composite material components in the current collecting foil, but also increased the proportion of current collecting foil components in the composite, resulting in greater damage to the current collecting foil. In Experimental Example 19, the ultrasonic frequency was also 40 kHz, but damage to the current collecting foil was less severe than in Experimental Example 18, possibly due to the use of water as the treatment solution.

[0072] From the above, it was found that by using water as the treatment liquid and performing ultrasonic treatment using the sweep function, the current collector and the electrode mixture can be separated efficiently and with high precision.

[0073] [Table 1]

[0074] [Table 2]

[0075] 2. Experimental Examples 20-28 However, if the waiting time for immersing the electrode (especially the positive electrode) in water before the separation by ultrasonic treatment is long, separation of the composite layer may become difficult. The reason for this is presumed to be as follows: When the positive electrode is immersed in water, alkali metal components (e.g., lithium) contained in the positive electrode active material dissolve, causing the water to become alkaline. It is presumed that the change in water alkalinity causes current collector components (e.g., aluminum) to dissolve into the water, which in turn causes a compound to form between the composite and aluminum, inhibiting separation and resulting in the composite remaining on the current collector. Therefore, in the following, in a method for separating the positive electrode current collector and the positive electrode composite by ultrasonic treatment, we investigated ways to suppress a decrease in the removal rate of the composite layer by adjusting at least one of the following: the waiting time [min] for placing the electrode to be treated in water before ultrasonic treatment, the pH [-] of the water after ultrasonic treatment, the amount of Li elution [mg / L] (the concentration of alkali metal components contained in the water after ultrasonic treatment), and the amount of Al elution [%] (the amount dissolved in water per weight of the current collector). FIG. 8 is a flowchart showing an example of the separation method in this embodiment.

[0076] [Electrode to be treated] The electrode to be treated was the above-mentioned positive electrode A. The proportion of the composite material in the positive electrode was 74 wt %.

[0077] [Ultrasonic treatment] Using an ultrasonic device (Branson GCX-M-3FQ12, output power 500W, cleaning tank capacity 20L), water (pure water, pH 6) was placed in the cleaning tank (outer tank), and 50 ml of aqueous solution was placed in the glass container of the inner tank. A positive electrode with an area of ​​40 mm x 100 mm was placed in the solution and immersed for the specified time. Ultrasonic waves were then applied from the transducer below the outer tank. The ultrasonic treatment conditions were a frequency of 120 kHz, a sweep width of ±1 kHz, a sweep speed of 1000 sweep cycles / second, and a treatment time of 60 seconds.

[0078] [analysis] The pH of the treated water, the weight of the positive electrode, and ICP-OES analysis were performed at the timings shown in Figure 8. For the ICP-OES analysis, an inductively coupled plasma optical emission spectrometer (ICP-OES, Hitachi High-Tech Science PS3520UVDDIII II) was used to measure the Li concentration (mg / L) in the treated water, the Al concentration (mg / L) in the treated water, and the weight ratio (%) of aluminum in the composite powder. The measured Li concentration (mg / L) was used as the amount of Li elution. The amount of Al elution into water per weight of the current collector (Al) was calculated from the measured Al concentration (mg / L), and this was used as the amount of Al elution. The amount of Al in the composite was determined in the same manner as in the above-mentioned [Analysis of the ratio of current-collector foil components in the composite]. The composite removal rate was also calculated from the weight measurement results. The composite removal rate is the percentage obtained by dividing the weight loss rate of the positive electrode before and after the separation process by the weight rate of the composite in the positive electrode, which is 74%. If the Al foil is damaged and its weight is reduced, this amount is also included in the composite removal rate.

[0079] [Results and Discussion] Table 3 summarizes the results of the water immersion waiting time [min], pH after ultrasonic treatment, Li elution amount [mg / L], Al elution amount [%], Al content in the composite powder [%], composite removal rate [%], and composite removal rate evaluation for Experimental Examples 20 to 28. The composite removal rate evaluation criteria were as follows: 99% or more (A), 97% to less than 99% (B), 90% to less than 97% (C), 80% to less than 90% (D), and less than 80% (F). In Table 3, the immersion waiting time "immediately after" indicates that ultrasonic waves were applied immediately after the positive electrode was immersed. Experimental Example 20 is an experimental example that underwent the same treatment as Experimental Example 3. Regarding Experimental Examples 20 to 28, damage to the current collector was evaluated by visually observing holes or chips in the foil, rating it as "damaged," and observing no holes or chips, rating it as "no damage." All results were "no damage."

[0080] FIG. 9 shows photographs of the electrode after ultrasonic treatment at various waiting times. FIG. 10 is a graph showing the relationship between waiting time and composite removal rate. FIG. 11 is a graph showing the relationship between the pH of water after ultrasonic treatment and the composite removal rate. FIG. 12 is a graph showing the relationship between the amount of Li elution and the composite removal rate. FIG. 13 is a graph showing the relationship between the amount of Al elution and the composite removal rate. FIG. 14 is a graph showing the relationship between the composite removal rate and the amount of Al in the composite powder. As shown in Table 3 and FIGS. 9 to 14, in Experimental Examples 20 to 28, a high composite removal rate of 90% or more was achieved. As shown in FIG. 10, the shorter the waiting time, the higher the composite removal rate. A waiting time of 30 minutes or less resulted in a composite removal rate of 90% or more, a waiting time of less than 5 minutes resulted in a composite removal rate of 97% or more, and a waiting time of less than 3 minutes resulted in a composite removal rate of 99% or more, which is more preferable. Furthermore, as shown in Figure 11, the lower the pH of the water after ultrasonic treatment, the higher the composite removal rate. At a pH of 11.5 or less, the composite removal rate was 90% or higher. At a pH of less than 11.4, the composite removal rate was 96% or higher. At a pH of less than 11.2, the composite removal rate was 99% or higher, which is more preferable. Furthermore, as shown in Figure 12, the lower the amount of Li elution, the higher the composite removal rate. At a Li elution rate of 37.5 mg / L or less, the composite removal rate was 90% or higher. At a Li elution rate of less than 33 mg / L, the composite removal rate was 97% or higher. At a Li elution rate of less than 32 mg / L, the composite removal rate was 99% or higher, which is more preferable. Furthermore, as shown in Figure 13, the lower the amount of Al elution, the higher the composite removal rate. At an Al elution rate of 1.1% or less, the composite removal rate was 90% or higher. At an Al elution rate of less than 1.0%, the composite removal rate was 97% or higher. At an Al elution rate of less than 0.9%, the composite removal rate was 99% or higher, which is more preferable. Thus, it was found that the reduction in the removal rate of the composite layer can be suppressed by adjusting at least one of the waiting time, the pH of the water after ultrasonic treatment, the amount of Li elution [mg / L], and the amount of Al elution [%]. Furthermore, as shown in Figure 14, the higher the composite removal rate, the lower the amount of Al in the composite powder. It was found that when the composite removal rate is 90% or more, the amount of Al in the composite powder is 0.18% or less, and when the composite removal rate is 99% or more, the amount of Al in the composite powder is less than 0.10%, which is more preferable.

[0081] [Table 3] [Industrial Applicability]

[0082] The present disclosure is applicable to the field of the battery industry. [Explanation of symbols]

[0083] 10 Separation device, 15 Control unit, 20 Ultrasonic device, 22 Treatment container, 24 Inner tank, 25 Mounting table, 26 Outer tank, 28 Vibrator, 30 Oscillator, 32 Treatment liquid, 33 Composite-containing treatment liquid, 36 Ultrasonic propagation medium, 50 Treatment target electrode, 52 Current collector, 54 Electrode composite, 60 Separation unit, 62 Pipe, 62a Valve, 70 Inlet unit, 72 Conveyor, 80 Current collector discharge unit, 82 Robot arm, 84 Conveyor, 86 Rinse device, 88 Drying device, 90 Composite discharge unit, 92 Pipe, 92a Valve, 94 Filter, 96 Conveyor, 98 Drying device.

Claims

1. a separation step of subjecting a treatment target electrode, which includes a current collector and an electrode composite formed on the current collector, to ultrasonic treatment in water while sweeping ultrasonic frequencies, to separate the current collector from the electrode composite; In the separating step, the sweep is performed with a sweep width within ±3 kHz centered on the fundamental frequency.

2. a separation step of subjecting a treatment target electrode, which includes a current collector and an electrode composite formed on the current collector, to ultrasonic treatment in water while sweeping ultrasonic frequencies, to separate the current collector from the electrode composite; A separation method, wherein in the separation step, the sweep is performed centered on a fundamental frequency of 80 kHz or more and 200 kHz or less.

3. The separation method according to claim 1 , wherein in the separation step, the sweep is performed centered on a fundamental frequency of 80 kHz to 200 kHz.

4. The separation method according to any one of claims 1 to 3, wherein in the separation step, the ultrasonic treatment is performed on the electrode to be treated, which includes the electrode mixture containing at least one binder of an organic binder and an aqueous binder.

5. 4. The separation method according to claim 1, wherein in the separation step, the sweep is performed at a sweep rate of 500 sweep cycles / second or more.

6. The separation method according to any one of claims 1 to 3, wherein the ultrasonic treatment is carried out for 10 minutes or less in the separation step.

7. In the separation step, the contact area between the current collector and the electrode mixture is A [cm 2 ], and the output of the ultrasonic wave is B [W], the output density expressed by B / A is 10 W / cm 2 The separation method according to any one of claims 1 to 3, wherein the ultrasonic treatment is carried out so that:

8. The separation method according to any one of claims 1 to 3, wherein a ratio of the current collector component in the electrode mixture separated in the separation step is less than 0.1%, and a ratio of the electrode mixture component in the current collector separated in the separation step is less than 0.2%.

9. The separation method according to any one of claims 1 to 3, wherein the ultrasonic treatment is performed in a non-heated environment in the separation step.

10. The separation method according to any one of claims 1 to 3, wherein the ultrasonic treatment is carried out in a batch or continuous manner.

11. The separation method according to any one of claims 1 to 3, a removal step of removing the electrode from the electricity storage device, In the separating step, the electrode removed in the removing step is used as the processing target electrode without being shredded, and the ultrasonic treatment is performed on the electrode.

12. 4. The separation method according to claim 1, comprising at least one of a current collector treatment step of rinsing and drying the current collector separated in the separation step, and a composite treatment step of separating the electrode composite from composite-containing water containing the electrode composite separated in the separation step and drying the electrode composite.

13. The separation method according to any one of claims 1 to 3, wherein the separation step is carried out so as to satisfy one or more of the following (1) to (6): (1) In the separation step, the pH of the water after the ultrasonic treatment is adjusted to 11.5 or less. (2) In the separation step, the concentration of alkali metal components contained in the water after the ultrasonic treatment is set to 37.5 mg / L or less. (3) In the separation step, the amount of the current collector dissolved in water is set to 1.1% or less per weight of the current collector. (4) In the separation step, the waiting time for placing the electrode to be treated in the water before the ultrasonic treatment is set to 30 minutes or less. (5) In the separation step, the weight ratio of the current collector component contained in the separated electrode mixture is set to 0.18% or less. (6) In the separation step, the removal rate of the electrode mixture from the current collector is set to 90% or more.

14. a separation unit that performs ultrasonic treatment in water on a treatment target electrode including a current collector and an electrode composite material formed on the current collector to separate the current collector and the electrode composite material; a control unit that controls the separation unit so that the ultrasonic processing is performed while sweeping the frequency of the ultrasonic waves; Equipped with The control unit controls the separation unit so as to satisfy at least one of the following: performing the sweep with a sweep width of ±3 kHz around the fundamental frequency, or performing the sweep around a fundamental frequency of 80 kHz or more and 200 kHz or less.

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