Method for processing electrodes and method for manufacturing electrodes

Abstract

To provide a processing method of a novel electrode capable of easily executing a recycle, and a manufacturing method of the electrode.SOLUTION: A processing method of an electrode comprises a separation step of immersing a treatment object positive electrode 10 having a positive mixture material 14 containing a positive electrode active material 16 and a binding material into a treatment agent 20 containing an aromatic hydrocarbon compound in a reduction state, a metal ion, and a treatment agent solvent as an ether system chemical compound, to separate the positive electrode active material 16 from the treatment object positive electrode 10, to thereby maintain a crystal structure of the positive electrode active material 16 before and after the separation step. Besides, a manufacturing method of an electrode comprises a positive electrode manufacturing step of manufacturing a new positive electrode using the positive electrode active material 16 that is separated from the treatment object positive electrode 10 in the above processing method of the electrode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This specification discloses methods for processing electrodes and methods for manufacturing electrodes. [Background technology]

[0002] Conventionally, methods for recycling electrodes have been proposed, for example, to decompose used cathode material with acid, extract it as hydroxide, and regenerate it back into oxide using lithium carbonate (see, for example, Non-Patent Document 1). Furthermore, methods have been proposed for adding mobile Li to the active material of deactivated LiCoO2 cathodes by hydrothermal synthesis using a LiOH / Li2SO4 aqueous solution, solid-phase synthesis using Li2CO3, or calcination (see, for example, Non-Patent Document 2). Also, Li in deactivated LiNiCoMnO2 cathodes... + A method has been proposed for imparting mobile Li to an active material using a molten salt containing (see, for example, Non-Patent Document 3). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Green Chem., 2013, 15, 1183-1191 [Non-Patent Document 2] Green Chem., 2018, 20, 851-862 [Non-Patent Document 3] Adv.Energy Mater.2019,9,1900454 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, Non-Patent Document 1 mentioned above required a multi-step process because it involved disassembling the electrode and then decomposing the positive electrode into its raw materials for resynthesis. Furthermore, Non-Patent Document 2 mentioned above required processing at high temperatures exceeding 800°C for hydrothermal synthesis and solid-phase synthesis. Additionally, Non-Patent Document 3 mentioned above required disassembling the electrode and processing the molten salt at high temperatures, which presented challenges in terms of energy consumption.

[0005] This disclosure has been made in view of these challenges and primarily aims to provide a novel electrode processing method and electrode manufacturing method that can facilitate recycling. [Means for solving the problem]

[0006] Through diligent research to achieve the above-mentioned objectives, the present inventors discovered that by immersing an electrode in a predetermined treatment agent for a predetermined time, the electrode active material can be separated from the electrode, and that the crystalline structure of the electrode active material is maintained before and after immersion, thus completing this disclosure.

[0007] That is, the electrode processing method disclosed herein is The process includes a separation step in which an electrode to be treated, comprising an electrode composite containing an electrode active material and a binder, is immersed in a treatment agent containing a treatment solvent which is a reduced aromatic hydrocarbon compound, metal ions, and an ether-based compound, thereby separating the electrode active material from the electrode to be treated, wherein the crystalline structure of the electrode active material is maintained before and after the separation step. It is.

[0008] The method for manufacturing electrodes disclosed herein is: The process includes an electrode fabrication step of fabricating a new electrode using the electrode active material separated from the electrode to be processed by the electrode processing method described above, It is. [Effects of the Invention]

[0009] The electrode processing method and electrode manufacturing method of this disclosure enable easier recycling. The reason for this effect is presumed to be as follows. For example, a processing agent containing a reduced aromatic hydrocarbon compound, metal ions, and a processing agent solvent which is an ether-based compound, donates electrons to a binder such as a fluorine-containing polymer, thereby promoting the carbonization of the binder and simultaneously reducing its binding properties. This allows for easy separation of the electrode active material from the electrode being processed. Furthermore, by adjusting the processing conditions with the processing agent, side reactions can be suppressed, and the electrode active material can be separated from the electrode being processed without destroying the crystal structure of the active material. Thus, in this disclosure, since the active material can be easily separated from the electrode being processed without destroying the crystal structure of the active material, there is no need to resynthesize the active material, and recycling can be made easier. [Brief explanation of the drawing]

[0010] [Figure 1] An explanatory diagram showing an example of the separation process. [Figure 2] Reaction equation for the reduction of the binder. [Figure 3] XRD patterns of the powders obtained in the separation steps of Experimental Examples 1-5. [Figure 4] XRD pattern of the powder obtained in the separation step of Experimental Example 7. [Modes for carrying out the invention]

[0011] The electrode treatment method and electrode manufacturing method of the present disclosure relate to electrodes for energy storage devices. Examples of energy storage devices include hybrid capacitors, pseudo electric double layer capacitors, alkali metal secondary batteries such as lithium and sodium, alkali metal ion batteries, air batteries, and the like. Metal ions as carrier ions include, for example, alkali metal ions such as Li, Na, K, and Group 2 ions (alkaline earth metal ions) such as Mg, Ca, Sr, etc., among which lithium ions are preferred. Among these, as the energy storage device, a lithium secondary battery, particularly a lithium ion secondary battery is preferred. Here, it will be mainly described on the assumption that the energy storage device is a lithium secondary battery. The energy storage device may include, for example, a positive electrode having a positive electrode active material that occludes and releases lithium ions, a negative electrode having a negative electrode active material that occludes and releases lithium ions, and an electrolytic solution that intervenes between the positive electrode and the negative electrode and conducts lithium ions. This energy storage device may also include a separator between the positive electrode and the negative electrode.

[0012] The positive electrode may include a positive electrode mixture containing a positive electrode active material and a binder. The positive electrode mixture may be formed on the surface of the current collector. The positive electrode mixture may include, in addition to the positive electrode active material and the binder, a conductive material and the like. For example, the positive electrode is formed by mixing a positive electrode active material, a binder, and, if necessary, a conductive material, adding an appropriate solvent to form a paste-like positive electrode mixture, applying and drying it on the surface of the current collector, and compressing it if necessary to increase the electrode density. Examples of the positive electrode active material include compounds containing lithium and transition metal elements, and oxides containing lithium and transition metal elements are preferred. The positive electrode active material has, for example, a basic composition formula of Li (1-x) MnO2 (0 < x < 1, etc., the same below), Li (1-x) Mn2O4 and other lithium manganese composite oxides, a basic composition formula of Li (1-x) CoO2 and other lithium cobalt composite oxides, a basic composition formula of Li (1-x) NiO2 and other lithium nickel composite oxides, a basic composition formula of Li (1-x) Ni a Co b Mn cLithium nickel cobalt manganese composite oxides such as O2 (a + b + c = 1) can be used. Alternatively, the cathode active material may be lithium iron phosphate. Note that the "basic composition formula" means that other elements may be included.

[0013] The binder serves to bind the active material particles and the conductive material particles. For example, fluorine-containing resins 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, natural butyl rubber (NBR), etc. can be used alone or as a mixture of two or more. Also, aqueous binders such as water dispersions of cellulose-based carboxymethyl cellulose (CMC), styrene-butadiene copolymer (SBR), polyvinyl alcohol, etc. can be used.

[0014] The conductive material is not particularly limited as long as it is an electron-conductive material that does not adversely affect battery performance. For example, graphite such as natural graphite (scaly graphite, flaky graphite) or artificial graphite, carbon materials such as acetylene black, carbon black, ketjen black, carbon whiskers, needle coke, carbon fibers, and one or more of metals (such as copper, nickel, aluminum, silver, gold, etc.) can be mixed and used. As the solvent for dispersing the positive electrode active material, conductive material, and binder, for example, organic solvents such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, N,N-dimethylaminopropylamine, ethylene oxide, and tetrahydrofuran can be used. Also, a dispersant, thickener, etc. can be added to water, and the active material can be slurried with a latex such as SBR. As the thickener, for example, polysaccharides such as carboxymethyl cellulose and methyl cellulose can be used alone or as a mixture of two or more. As the coating method, for example, roller coating such as an applicator roll, screen coating, doctor blade method, spin coating, bar coater, etc. can be mentioned, and any thickness and shape can be obtained using any of these. As the current collector, in addition to aluminum, titanium, stainless steel, nickel, iron, fired carbon, conductive polymer, conductive glass, etc., for the purpose of improving adhesion, conductivity, and oxidation resistance, those with the surface of aluminum, copper, etc. treated with carbon, nickel, titanium, silver, etc. can be used. For these, it is also possible to perform an oxidation treatment on the surface. Regarding the shape of the current collector, examples include foil-like, film-like, sheet-like, net-like, punched or expanded ones, lath bodies, porous bodies, foams, and formed bodies of fiber groups. The thickness of the current collector is, for example, 1 to 500 μm.

[0015] The negative electrode may comprise a negative electrode composite material containing a negative electrode active material and a binder. The negative electrode composite material may be formed on the surface of the current collector. In addition to the negative electrode active material and binder, the negative electrode composite material may also contain conductive materials. The negative electrode may be formed, for example, by mixing the negative electrode active material, binder, and conductive material as needed, adding a suitable solvent to form a paste-like negative electrode composite material, coating and drying it on the surface of the current collector, and compressing it to increase the electrode density as needed. Examples of negative electrode active materials include inorganic compounds such as lithium, lithium alloys, and tin compounds, carbon materials capable of intercalating and deintercalating lithium ions, composite oxides containing multiple elements, and conductive polymers. Examples of carbon 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. For the negative electrode binder, conductive material, solvent, coating method, and current collector, one or more of those exemplified for the positive electrode can be used.

[0016] The electrolyte can be, for example, an electrolyte in which a supporting salt is dissolved. Examples of supporting salts include lithium salts such as LiPF6 and LiBF4. Examples of solvents for the electrolyte include carbonates, esters, ethers, nitriles, furans, sulforanes, and dioxolanes, which can be used individually or in mixtures. Specifically, examples of carbonates include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), butylene carbonate, and chloroethylene carbonate, as well as linear carbonates such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate, ethyl-n-butyl carbonate, methyl-t-butyl carbonate, di-i-propyl carbonate, and t-butyl-i-propyl carbonate. Furthermore, the electrolyte can be a solid ion-conducting polymer, an inorganic solid electrolyte, a mixed material of an organic polymer electrolyte and an inorganic solid electrolyte, or an inorganic solid powder bound together by an organic binder.

[0017] [Electrode Processing Method] The electrode processing method of this disclosure includes a separation step of immersing an electrode to be processed, which is equipped with an electrode mixture containing an electrode active material and a binder, in a processing agent to separate the electrode active material from the electrode to be processed. In this electrode processing method, the crystalline structure of the electrode active material is maintained before and after the separation step.

[0018] (Electrode to be processed) The electrode to be treated may be the positive or negative electrode of the energy storage device described above, but it is preferable that it be the positive electrode. The electrode to be treated is preferably an oxide containing the same type of metal ions as those contained in the treatment agent described later, preferably a lithium transition metal composite oxide, and more preferably a composite oxide containing lithium, nickel, manganese, and cobalt. Furthermore, the binder contained in the electrode to be treated preferably contains a fluorine-containing polymer (fluororesin) such as polyvinylidene fluoride. The electrode to be treated may be new, such as leftover scraps from the electrode manufacturing process, or it may be a used product. In this electrode to be treated, the electrode active material is preferably in a state where it can intercept and release carrier ions, and is preferably not deactivated.

[0019] (Treatment agent) The treatment agent comprises a reduced aromatic hydrocarbon compound, a metal ion, and a treatment agent solvent which is an ether-based compound. The metal ion is preferably of the same type as the carrier ions in the energy storage device. Furthermore, the treatment agent solvent is preferably different from the electrolyte solvent used in the energy storage device. Additionally, the treatment agent is preferably a solution that does not contain the electrolyte solvent used in the energy storage device. This treatment agent may be dark green in color.

[0020] The treatment agent contains an aromatic hydrocarbon compound in a reduced state and a metal ion. This treatment agent may contain one or more aromatic hydrocarbon compounds from the following formulas (1) and (2). Alternatively, the treatment agent may be obtained from one or more of the following formulas (3) and (4). That is, an aromatic hydrocarbon compound may be reacted with a metal to contain an aromatic hydrocarbon compound in a reduced state and a metal ion. The metal is preferably highly reactive to react with the aromatic hydrocarbon compound, and alkali metals or metals of group 2 are preferred. This treatment agent may contain one or more aromatic hydrocarbon compounds from among naphthalene, biphenyl, ortho-terphenyl, anthracene, and para-terphenyl. Naphthalene and biphenyl are preferred as aromatic hydrocarbon compounds. The treatment agent may also contain one or more metal ions from among lithium ions, sodium ions, and potassium ions. Of these metal ions, lithium ions are more preferred.

[0021] Furthermore, the treatment agent contains an ether-based compound as the treatment agent solvent. This treatment agent solvent may be, for example, a cyclic ether-based compound or a chain-like ether-based compound. Examples of this treatment agent solvent include one or more of tetrahydrofuran (THF), dioxolane (DOL), dioxane (DOX), diethyl ether (DEE), dimethoxyethane (DME), diglyme (G2), triglyme (G3), and tetraglyme (G4), of which DME and THF are more preferred, and DME is even more preferred. For example, as shown in formulas (5) to (7), it is preferable to use a treatment agent solvent of DME and to react Li metal with either naphthalene, biphenyl, or orthoterphenyl. Using such a treatment agent makes it easier to separate the electrode active material from the electrode, and at that time, it is easier to maintain the crystalline structure of the electrode active material.

[0022] In this treatment agent, the concentration of the reduced aromatic hydrocarbon compound relative to the total treatment agent is preferably greater than 0.1 mol / L, more preferably 0.2 mol / L or higher, and even more preferably 0.25 mol / L or higher. Furthermore, this concentration is preferably 3 mol / L or lower, more preferably 2 mol / L or lower, and even more preferably 1 mol / L or lower. When the treatment agent solvent is THF, this concentration is even more preferably 0.5 mol / L or lower. The higher this concentration, the easier it is to separate the electrode active material from the electrode, for example, allowing for separation in a shorter time.

[0023] [ka]

[0024] [ka]

[0025] [ka]

[0026] (separation process) In the separation step, the electrode to be treated is immersed in the treatment agent. The temperature (also called the treatment temperature) is not particularly limited and may be in the range of 10°C to 60°C or 20°C to 40°C. A treatment temperature near room temperature (20°C to 25°C) is preferable. The immersion time of the electrode to be treated should be set appropriately so that the electrode active material can be separated from the electrode and the crystalline structure of the electrode active material is maintained before and after the separation step. For example, 5 minutes to less than 1 hour is preferable, 10 minutes to 45 minutes is more preferable, and 15 minutes to 30 minutes is even more preferable. The shorter the treatment time, the less likely the treatment agent is to reach the electrode active material, and the easier it is to maintain the crystalline structure of the electrode active material. Therefore, it is presumed that in the separation step, for example, by using a reducing agent with a relatively high concentration of reduced hydrocarbon compounds and shortening the treatment time, the electrode active material can be separated from the electrode more reliably, and the crystalline structure of the electrode active material can be maintained before and after the separation step. In this separation step, the treatment agent after immersion may be filtered to separate the powder containing the electrode active material. Alternatively, the filtered powder may be washed with water or an organic solvent.

[0027] In this separation process, the electrode active material can be separated from the electrode by simply immersing the electrode to be treated, which is equipped with an electrode composite containing electrode active material and a binder, in a treatment agent solution containing a reduced aromatic hydrocarbon compound, metal ions, and a treatment agent solvent which is an ether-based compound. For example, as shown in Figure 1, when the positive electrode 10 is immersed in the treatment agent 20, the reaction shown in Figure 2 proceeds, the binding properties of the binder contained in the positive electrode composite 14 decrease, and the positive electrode 10 decomposes into a current collector 12, positive electrode active material 16, and composite material component 18. The composite material component 18 contains conductive materials other than the positive electrode active material, as well as binder components. In this way, the electrode active material can be separated from the electrode in this separation process. Furthermore, in this separation process, the crystalline structure of the electrode active material can be maintained before and after the separation process by adjusting the processing conditions in the treatment agent.

[0028] [Method for manufacturing electrodes] The electrode manufacturing method of this disclosure includes an electrode manufacturing step of manufacturing a new electrode using electrode active material separated from the electrode to be processed by the electrode processing method described above. In the electrode manufacturing step, the electrode may be manufactured by applying an electrode composite material, obtained by mixing the electrode active material with a binder and a conductive material as needed, to a current collector. In this electrode manufacturing method, one or more of those exemplified for the positive electrode can be used as the binder, conductive material, solvent, coating method, and current collector, respectively.

[0029] The electrode processing method and electrode manufacturing method of this embodiment described above allow for easier recycling. The reason for this effect is presumed to be as follows. For example, a processing agent containing a reduced aromatic hydrocarbon compound, metal ions, and a processing agent solvent which is an ether-based compound, donates electrons to a binder such as a fluorine-containing polymer, thereby promoting the carbonization of the binder and simultaneously reducing its binding properties. This allows for easy separation of the electrode active material from the electrode being processed. Furthermore, by adjusting the processing conditions with the processing agent, side reactions are suppressed, and the electrode active material can be separated from the electrode being processed without destroying the crystal structure of the active material. Thus, in this disclosure, since the active material can be easily separated from the electrode being processed without destroying the crystal structure of the active material, there is no need to resynthesize the active material, and recycling can be made easier.

[0030] It should be noted 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. For example, in the embodiments described above, if used materials are used as electrodes to be processed, an introduction step may be performed to introduce metal ions that will serve as carrier ions into the electrode active material before the separation step, after the separation step, or after the electrode fabrication step.

[0031] This disclosure may be any of the following [1] to

[10] . [1] A method for treating an electrode, comprising a separation step of immersing an electrode to be treated, which is an electrode composite containing an electrode active material and a binder, in a treatment agent containing a treatment agent solvent which is an aromatic hydrocarbon compound in a reduced state, a metal ion and an ether compound, thereby separating the electrode active material from the electrode to be treated, wherein the crystalline structure of the electrode active material is maintained before and after the separation step. [2] The electrode treatment method according to [1], wherein in the separation step, the treatment time for immersing the electrode to be treated in the treatment agent is 5 minutes or more and less than 1 hour. [3] The electrode treatment method according to [1] or [2], wherein in the separation step, the treatment time for immersing the electrode to be treated in the treatment agent is 15 minutes or more and 30 minutes or less. [4] The electrode treatment method according to any one of [1] to [3], wherein the separation step uses the treatment agent containing the reduced aromatic hydrocarbon compound at a concentration exceeding 0.1 mol / L. [5] The electrode treatment method according to any one of [1] to [4], wherein the separation step uses the treatment agent containing the reduced aromatic hydrocarbon compound at a concentration of 0.25 mol / L or more and 1 mol / L or less. [6] The method for treating an electrode according to any one of [1] to [5], wherein the binder comprises a fluorine-containing polymer. [7] The electrode processing method according to any one of [1] to [6], wherein the electrode active material is an oxide containing the metal ions. [8] The method for treating an electrode according to any one of [1] to [7], wherein the aromatic hydrocarbon compound is one or more compounds from formulas (1) to (2). [C1] [9] The method for treating an electrode according to any one of [1] to [8], wherein the treatment solvent comprises one or more of the following: dimethoxyethane (DME), tetrahydrofuran (THF), diethyl ether (DEE), diglyme (G2), triglyme (G3), and tetraglyme (G4). A method for manufacturing an electrode, comprising an electrode manufacturing step of manufacturing a new electrode using the electrode active material separated from the electrode to be processed by the electrode processing method described in any one of [1], [1], to [9]. [Examples]

[0032] The following describes experimental examples that specifically examine the electrode processing method of this disclosure. Experimental Examples 1 to 5 correspond to embodiments of this disclosure, and Experimental Examples 6 to 7 correspond to comparative examples.

[0033] [Experimental Example 1] (Electrode to be processed) The positive electrode of the following energy storage device was used as the electrode to be processed. The positive electrode of the energy storage device contained LiNi as the positive electrode active material. 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 Co., Ltd.) as a conductive material, and 3% by mass of polyvinylidene fluoride (manufactured by Kureha Corporation) as a binder, with a basis weight of 7 mg / cm³. 2 A material formed on one side of an aluminum current collector foil was used. Li metal was used for the negative electrode. The electrolyte was a mixed solvent containing 30% by volume of ethylene carbonate (EC), 40% by volume of dimethyl carbonate (DMC), and 30% by volume of ethyl methyl carbonate (EMC), in which LiPF6 was dissolved to a concentration of 1.1 M.

[0034] (Treatment agent) Under an inert atmosphere, naphthalene was dissolved in 1,2-dimethoxyethane (DME) solvent to a concentration of 1.0 mol / L. Then, lithium metal equivalent to 1.00 mol / L was added and the mixture was stirred to prepare a dark green anionic radical liquid composition with a lithium naphthalenide (Li-Naph) concentration of 1.00 mol / L by the reaction shown in formula (5) above. The prepared anionic radical liquid composition was used as a treatment agent.

[0035] (Separation process and evaluation) For 10 mL of the prepared treatment solution, add 10 cm to the electrode to be treated. 2The material was then immersed and stirred for 15 minutes. Afterward, filtration was performed using DME as the washing solvent. The presence or absence of filtration material was checked; if filtration material was present, the electrode mixture was considered detachable; if no filtration material was present, the electrode mixture was considered detachable. Furthermore, the obtained powdered filtration material was subjected to X-ray diffraction (XRD) measurement using an X-ray diffraction analyzer (Ultima IV, Rigaku) ​​to confirm its crystal structure. For the XRD measurement, CuKα (wavelength 1.54051 Å) was used, with an applied voltage of 40 kV, a current of 30 mA, a sampling width of 0.020° / min., and a scan speed of 5° min. -1 Measurements were taken within an angular range of 15° to 50° (2θ).

[0036] [Experimental Example 2] Experimental Example 2 was conducted in the same manner as Experimental Example 1, except that a further water wash was performed after the filtration process.

[0037] [Experimental Examples 3-6] Experimental Example 3 was conducted in the same manner as Experimental Example 1, except that tetrahydrofuran (THF) solvent was used instead of DME solvent as the solvent for the treatment agent. Experimental Example 4 was conducted in the same manner as Experimental Example 3, except that the concentration of Li-Naph in the treatment agent was 0.50 mol / L. Experimental Example 5 was conducted in the same manner as Experimental Example 3, except that the concentration of Li-Naph in the treatment agent was 0.25 mol / L. Experimental Example 6 was conducted in the same manner as Experimental Example 3, except that the concentration of Li-Naph in the treatment agent was 0.10 mol / L.

[0038] [Experimental Example 7] Experimental Example 7 was conducted in the same manner as Experimental Example 3, except that the immersion time of the electrode to be treated in the treatment agent was set to 1 hour.

[0039] [Results and Discussion] Table 1 summarizes the treatment agent composition, treatment time, post-treatment, feasibility of exfoliation, and whether the crystal structure was maintained for Experimental Examples 1-7. Figure 3 shows the XRD patterns of the powders obtained in the separation steps of Experimental Examples 1-5, and Figure 4 shows the XRD pattern of the powder obtained in the separation step of Experimental Example 7. For comparison, Figures 3 and 4 also show the XRD patterns of untreated electrodes that did not undergo the separation step. Note that the XRD patterns in Figure 4 were measured using a different XRD diffraction analyzer than that used in Figure 3, but it was confirmed that equivalent results were obtained from both methods based on the XRD patterns of the untreated electrodes.

[0040] As shown in Table 1 and Figures 3 and 4, in Experimental Examples 1-5, where the lithium naphthalenide concentration was between 0.25 mol / L and 1.0 mol / L and the treatment time was 15 minutes, peaks similar to those of the untreated positive electrode were observed, indicating that the crystal structure was removed without being destroyed. On the other hand, in Experimental Example 6, where the lithium naphthalenide concentration was 0.1 mol / L and the treatment time was 15 minutes, no removal was observed. Furthermore, in Experimental Example 7, where the lithium naphthalenide concentration was 1.0 mol / L and the treatment time was 1 hour, the X-ray peak of the obtained powder disappeared, indicating that the crystal structure was destroyed by the prolonged immersion treatment. In Experimental Examples 3 and 4, where THF was used as the treatment solvent and the lithium naphthalenide concentrations were relatively high (1.00 mol / L and 0.50 mol / L), slight peaks were observed around 30° and 33°, which were not seen in Experimental Examples 1 and 2, where DME was used as the treatment solvent. These peaks were presumed to indicate the occurrence of some kind of abnormal phase. On the other hand, in Experimental Example 5, where the treatment solvent was THF and the lithium naphthalenide concentration was 0.25 mol / L, no such peaks were observed. Therefore, from the viewpoint of suppressing the generation of a different phase, it is preferable to use DME as the treatment solvent, and when using THF as the treatment solvent, it was found that a lithium naphthalenide concentration of, for example, less than 0.5 mol / L or 0.3 mol / L or less is preferable. It was also inferred that the feasibility of peeling and whether or not the crystal structure is maintained depends on the type of treatment solvent, the concentration of lithium naphthalenide, and the treatment conditions such as the treatment time, so it is desirable to adopt appropriately suitable treatment conditions. In Experimental Examples 1 to 7, electrodes obtained by forming the composite material on current collector foil were used as the electrodes to be treated, but it was inferred that similar results could be obtained if electrodes removed from energy storage devices or discarded electrodes were used as the electrodes to be treated.

[0041] [Table 1]

[0042] 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. [Industrial applicability]

[0043] This disclosure is applicable to the field of energy storage devices. [Explanation of symbols]

[0044] 10 Positive electrode, 12 Current collector, 14 Positive electrode composite material, 16 Positive electrode active material, 18 Composite material component, 20 Treatment agent.

Claims

1. The process includes a separation step in which an electrode to be treated, comprising an electrode composite containing an electrode active material and a binder, is immersed in a treatment agent containing a treatment solvent which is a reduced aromatic hydrocarbon compound, a metal ion, and an ether-based compound, thereby separating the electrode active material from the electrode to be treated, wherein the crystalline structure of the electrode active material is maintained before and after the separation step. The aforementioned aromatic hydrocarbon compound is one or more compounds from formulas (1) to (2), The aforementioned metal ion is one or more of lithium ions, sodium ions, and potassium ions. The aforementioned treatment agent solvent is one or more of the following: dimethoxyethane (DME), tetrahydrofuran (THF), diethyl ether (DEE), diglyme (G2), triglyme (G3), and tetraglyme (G4). In the separation step, the treatment agent containing the reduced aromatic hydrocarbon compound at a concentration exceeding 0.1 mol / L is used, and the treatment time for immersing the electrode to be treated in the treatment agent is 5 minutes or more and less than 1 hour. Method for processing electrodes. 【Chemistry 1】

2. The electrode treatment method according to claim 1, wherein in the separation step, the treatment time for immersing the electrode to be treated in the treatment agent is 15 minutes or more and 30 minutes or less.

3. The electrode treatment method according to claim 1 or 2, wherein the separation step uses the treatment agent containing the reduced aromatic hydrocarbon compound at a concentration of 0.25 mol / L or more and 1 mol / L or less.

4. The electrode treatment method according to claim 1 or 2, wherein the binder includes a fluorine-containing polymer.

5. The electrode processing method according to claim 1 or 2, wherein the electrode active material is an oxide containing the metal ions.

6. The electrode treatment method according to claim 1 or 2, wherein the aromatic hydrocarbon compound is one or more of naphthalene and biphenyl.

7. The electrode processing method according to claim 1 or 2, wherein the metal ion is a lithium ion.

8. The method for treating an electrode according to claim 1 or 2, wherein the treatment solvent is one or more of dimethoxyethane (DME) and tetrahydrofuran (THF).

9. A method for manufacturing an electrode, comprising an electrode manufacturing step of manufacturing a new electrode using the electrode active material separated from the electrode to be processed by the electrode processing method according to claim 1 or 2.

Images