Deactivating agents and deactivation methods

Abstract

To provide a novel deactivator and a novel deactivation method capable of deactivating a nonaqueous secondary battery.SOLUTION: A deactivator for deactivating a nonaqueous secondary battery contains: a redox shuttle agent whose redox potential is higher than that of a negative electrode active material of the nonaqueous secondary battery and lower than that of a positive electrode active material of the nonaqueous secondary battery, at an Li reference potential; and a nonaqueous solvent that contains a carboxylic acid ester compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to deactivating agents and deactivation methods. [Background technology]

[0002] Conventionally, when recycling or disposing of nonaqueous secondary batteries, inactivation treatment is performed to inactivate the recovered batteries. For example, one possible treatment is to connect the recovered batteries to a charge / discharge device and discharge them to 0 V. However, this can take a long time to discharge. Furthermore, if the recovered batteries have a current interrupt device (CID), they cannot be discharged at all. Therefore, it has been proposed to add a redox shuttle agent (e.g., ferrocene) that exhibits a redox potential in the range of 3.0 to 4.5 V relative to the redox potential of lithium to the recovered batteries (see Patent Document 1). This allows the battery voltage of nonaqueous secondary batteries to be safely and quickly reduced to 0 V without using a charge / discharge device. Furthermore, a method has been proposed in the past for removing carbon from the copper foil surface of a negative electrode sheet of a lithium-ion battery using an aqueous release agent (see, for example, Patent Documents 2 and 3). This method claims to significantly reduce recycling costs by recovering the copper foil and carbon using the release agent. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-137137 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-26566 [Patent Document 3] Japanese Patent Application Laid-Open No. 2007-179774 Summary of the Invention [Problem to be solved by the invention]

[0004] However, while the deactivator of Patent Document 1 can deactivate nonaqueous secondary batteries, in consideration of simplification of processes such as deactivation and disposal of nonaqueous secondary batteries, as well as safety, the types of solvents that dissolve the redox shuttle agent have not yet been sufficiently studied, and a new, better deactivator has been desired.

[0005] The present disclosure has been made to solve such problems, and a main object of the present disclosure is to provide a novel deactivating agent and deactivation method for deactivating non-aqueous secondary batteries. [Means for solving the problem]

[0006] As a result of intensive research to achieve the above-mentioned object, the present inventors have found that a nonaqueous secondary battery can be inactivated by using a carboxylic acid ester compound as a nonaqueous solvent of a deactivator, and have thus completed the invention of the present disclosure.

[0007] That is, the deactivating agent of the present disclosure is A deactivator for deactivating a non-aqueous secondary battery, a redox shuttle agent having an oxidation-reduction potential, relative to a Li reference potential, higher than that of a negative electrode active material of the nonaqueous secondary battery and lower than that of a positive electrode active material of the nonaqueous secondary battery; a non-aqueous solvent containing a carboxylic acid ester compound; It includes:

[0008] The inactivation method of the present disclosure also includes: A method for deactivating a non-aqueous secondary battery, comprising: The method includes adding the above-mentioned deactivator for non-aqueous secondary batteries to the inside of the non-aqueous secondary battery. [Effects of the Invention]

[0009] This deactivator and deactivation method can deactivate nonaqueous secondary batteries. The reason for this effect is presumed to be as follows: When a redox shuttle agent with a redox potential lower than the positive electrode potential and higher than the negative electrode potential is added to a charged nonaqueous secondary battery, the potential difference between each electrode and the redox shuttle agent serves as a driving force to discharge the battery, thereby deactivating the battery. Furthermore, the use of a nonaqueous solvent containing a carboxylic acid ester compound can, for example, act on the electrode binder and promote separation between the current collector and the electrode mixture. Furthermore, the use of a nonaqueous solvent containing a carboxylic acid ester compound can, for example, increase the flash point of the electrolyte used in the nonaqueous secondary battery, thereby further improving safety during disposal of the nonaqueous secondary battery. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing the outline of the configuration of a nonaqueous secondary battery 20. FIG. [Figure 2] FIG. 2 is an explanatory diagram showing the mechanism by which a nonaqueous secondary battery is deactivated. [Figure 3] Discharge behavior after adding the passivating agents of Experimental Examples 1 and 2 to a fully charged evaluation cell. [Figure 4] Photographs showing examples of the peeled state of electrode mixtures in Experimental Examples 3 to 5. [Figure 5] Photographs showing the peeled state of the electrode mixture after ultrasonic treatment in Experimental Examples 6 to 8. DETAILED DESCRIPTION OF THE INVENTION

[0011] (deactivating agent) The non-aqueous secondary battery deactivator of the present disclosure comprises a redox shuttle agent and a non-aqueous solvent. The redox shuttle agent is a compound whose oxidation-reduction potential, relative to the Li reference potential, is higher than that of the negative electrode active material of the non-aqueous secondary battery and lower than that of the positive electrode active material of the non-aqueous secondary battery. In this specification, the redox shuttle agent refers to a compound that can be oxidized and reduced and that can repeatedly transport charge between the positive electrode and the negative electrode. The non-aqueous solvent comprises a carboxylic acid ester compound.

[0012] [Non-aqueous secondary battery] First, the non-aqueous secondary battery to be deactivated will be described. The non-aqueous secondary battery includes a positive electrode having a positive electrode active material, a negative electrode having a negative electrode active material, and a non-aqueous ion conductive medium interposed between the positive electrode and the negative electrode and conducting carrier ions. Examples of the carrier ions include Group 1 element ions and Group 2 element ions. Examples of the Group 1 element ions include lithium ions, sodium ions, and potassium ions. Examples of the Group 2 element ions include magnesium ions and calcium ions. Hereinafter, for the sake of convenience of explanation, the case where the non-aqueous secondary battery is a lithium ion secondary battery with a carbon material as the negative electrode active material will be mainly described.

[0013] The positive electrode may be formed by, for example, mixing a positive electrode active material, a conductive material, and a binder, adding an appropriate solvent to form a paste-like positive electrode mixture, applying and drying it on the surface of a current collector, and compressing it as necessary to increase the electrode density. The positive electrode active material may have an oxidation-reduction potential based on Li higher than that of the redox shuttle agent contained in the deactivator, and may have an oxidation-reduction potential exceeding 3.0 V based on the Li standard potential, preferably 3.5 V or more, more preferably 3.8 V or more, and even more preferably 4.0 V or more. As the positive electrode active material, sulfides containing transition metal elements, oxides containing lithium and transition metal elements, etc. can be used. Specifically, transition metal sulfides such as TiS2, TiS3, MoS3, FeS2, Li (1-x) MnO2 (0 < x < 1, etc., the same hereinafter), Li (1-x) lithium manganese composite oxides such as Mn2O4, Li (1-x) lithium cobalt composite oxides such as CoO2, Li (1-x) lithium nickel composite oxides such as NiO2, Li (1-x) Ni a Mn b O2 (a + b = 1) or Li (1-x) Ni a Mn b lithium nickel manganese composite oxides such as O4 (a + b = 2), Li (1-x) Nia Co b Mn c Lithium nickel cobalt manganese composite oxides such as O2 (a+b+c=1), lithium vanadium composite oxides such as LiV2O3, and transition metal oxides such as V2O5 can be used. (1-x) Olivine-type lithium manganese phosphate compounds such as MnPO4, Li (1-x) Olivine-type lithium cobalt phosphate compounds such as CoPO4, Li (1-x) Olivine-type lithium nickel phosphate compounds such as NiPO4 can be used. (1-x) Inverse spinel lithium manganese vanadate compounds such as MnVO4, Li (1-x) Inverse spinel lithium cobalt vanadate compounds such as CoPO4, Li (1-x) Inverse spinel lithium vanadate nickel compounds such as NiPO4 can be used. The positive electrode active material is preferably an oxide containing one or more of nickel, manganese, and cobalt, such as LiCoO2, LiNiO2, LiMnO2, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and the like are preferred.

[0014] Examples of conductive materials that can be used for the positive electrode include graphite, such as natural graphite (scale graphite, flake graphite) and artificial graphite, acetylene black, carbon black, ketjen black, carbon whiskers, needle coke, carbon fiber, and metals (copper, nickel, aluminum, silver, gold, etc.). Examples of binders that can be used include fluorine-containing resins such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), and fluorine-containing rubber, thermoplastic resins such as polypropylene and polyethylene, ethylene propylene diene rubber (EPDM), sulfonated EPDM rubber, and natural butyl rubber (NBR). Additionally, aqueous binders such as aqueous dispersions of cellulose-based materials like carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR) can also be used. Examples of solvents that can be used include organic solvents such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, N,N-dimethylaminopropylamine, ethylene oxide, and tetrahydrofuran. Alternatively, dispersants, thickeners, etc. can be added to water, and the active material can be slurried with a latex such as SBR. Examples of thickeners include polysaccharides such as carboxymethyl cellulose and methyl cellulose, either alone or in combination. Application methods include roller coating (e.g., applicator roll), screen coating, doctor blade coating, spin coating, and bar coating. Any of these can be used to achieve any desired thickness and shape. Examples of current collectors include aluminum, titanium, stainless steel, nickel, iron, calcined carbon, conductive polymers, and conductive glass. For the purpose of improving adhesion, conductivity, and oxidation resistance, aluminum and copper surfaces treated with carbon, nickel, titanium, or silver can also be used. These surfaces can also be subjected to oxidation treatment. The current collector may be in the form of a foil, film, sheet, net, punched or expanded, lath, porous, foamed, fiber group formed, etc. The thickness of the current collector is, for example, 1 to 500 μm.

[0015] The negative electrode may be formed, for example, by mixing a negative electrode active material, a conductive material, and a binder, adding an appropriate solvent to form a paste-like negative electrode mixture, applying it to the surface of a current collector, drying it, and compressing it to increase electrode density as needed. Alternatively, the negative electrode may be formed by closely adhering the negative electrode active material to the current collector. The redox potential of the negative electrode active material is preferably 3.0 V or less, more preferably 2.0 V or less, and even more preferably 1.0 V or less, relative to the Li reference potential. Examples of negative electrode active materials include inorganic compounds such as lithium, 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 Li4Ti5O 12 Examples of the negative electrode active material include lithium titanium composite oxides such as LiV2O3 and lithium vanadium composite oxides such as LiV2O3. Of these, carbonaceous materials such as graphite are preferred as the negative electrode active material. The conductive materials, binders, solvents, etc. used in the negative electrode can be the same as those exemplified for the positive electrode. For the negative electrode current collector, copper, nickel, stainless steel, titanium, aluminum, baked carbon, conductive polymers, conductive glass, Al-Cd alloys, etc. can be used. For the purpose of improving adhesion, conductivity, and reduction resistance, copper or other materials whose surfaces have been treated with carbon, nickel, titanium, silver, etc. can also be used. The surfaces of these materials can also be oxidized. The shape of the current collector can be the same as that of the positive electrode.

[0016] At least one of the positive and negative electrodes preferably contains at least SBR as a binder. When the electrode contains SBR as a binder, the electrode mixture can be peeled from the current collector by adding a deactivator, due to the relationship with the nonaqueous solvent of the deactivator. Nonaqueous secondary batteries are disassembled and discarded after being deactivated, but the use of this deactivator and electrode simplifies the disassembly process because the process of peeling the electrode mixture can be omitted.

[0017] Examples of the ion-conducting medium include a nonaqueous electrolyte solution containing a supporting salt and a nonaqueous gel electrolyte solution. Examples of solvents for nonaqueous electrolyte solutions include carbonate compounds, ester compounds, ether compounds, nitrile compounds, amide compounds, furan compounds, sulfolane compounds, and dioxolane compounds, which can be used alone or in combination. Specific examples of carbonate compounds include cyclic carbonate compounds such as ethylene carbonate (EC), propylene carbonate, vinylene carbonate, butylene carbonate, and chloroethylene carbonate, and chain carbonate compounds such as dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethyl-n-butyl carbonate, methyl-t-butyl carbonate, di-i-propyl carbonate, and t-butyl-i-propyl carbonate. Examples of ester compounds include cyclic ester compounds such as γ-butyllactone and γ-valerolactone, and chain ester compounds such as methyl formate, methyl acetate, ethyl acetate, and methyl butyrate. Examples of ether compounds include dimethoxyethane, ethoxymethoxyethane, and diethoxyethane. Examples of nitrile compounds include acetonitrile and benzonitrile. Examples of amide compounds include dimethylacetamide (DMA) and dimethylformamide. Examples of furan compounds include tetrahydrofuran and methyltetrahydrofuran. Examples of sulfolane compounds include sulfolane and tetramethylsulfolane. Examples of oxolane compounds include 1,3-dioxolane and methyldioxolane. These compounds can be used alone or in combination. Among these, a mixture of a cyclic carbonate compound and a chain carbonate compound, such as DMC-EC, DEC-EC, or DMC-EMC-EC, is preferred as the solvent for the nonaqueous electrolyte. Examples of supporting salts include inorganic salts such as LiPF6, LiBF4, LiAsF6, and LiClO4, and organic salts such as LiCF3SO3, LiN(CF3SO2)2, and LiC(CF3SO2)3, and these can be used alone or in combination.The concentration of the supporting salt in the electrolyte is preferably 0.1 mol / L to 5 mol / L, more preferably 0.5 mol / L to 2 mol / L. As the ion-conducting medium, an 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 by an organic binder can be used instead of a liquid ion-conducting medium.

[0018] This nonaqueous secondary battery may include a separator between the positive electrode and the negative electrode. The separator is not particularly limited as long as it has a composition that can withstand the range of use of the nonaqueous secondary battery, but examples thereof include polymer nonwoven fabrics such as polypropylene nonwoven fabrics and thin microporous films of olefin resins such as polyethylene. These may be used alone or in combination.

[0019] The shape of this nonaqueous secondary battery is not particularly limited, and examples thereof include coin, button, sheet, laminate, cylindrical, flat, and prismatic types. Large-sized batteries for use in electric vehicles and the like may also be used. An example of a nonaqueous secondary battery is shown in FIG. 1. FIG. 1 is a cross-sectional view showing the schematic configuration of a coin-type nonaqueous secondary battery 20. As shown in FIG. 1, the nonaqueous secondary battery 20 includes a cup-shaped battery case 21, a positive electrode 22 having a positive electrode active material and disposed at the bottom of the battery case 21, a negative electrode 23 having a negative electrode active material and disposed opposite the positive electrode 22 with a separator 24 interposed therebetween, a gasket 25 formed of an insulating material, and a sealing plate 26 disposed at the opening of the battery case 21 and sealing the battery case 21 via the gasket 25. The nonaqueous secondary battery 20 includes an ion-conducting medium 27 containing a lithium salt dissolved in the space between the positive electrode 22 and the negative electrode 23. In addition, it is preferable that either the positive electrode 22 or the negative electrode 23 of this nonaqueous secondary battery 20 contains SBR as a binder.

[0020] [Deactivating agent] Next, the deactivator will be described. The deactivator includes a redox shuttle agent and a non-aqueous solvent. The non-aqueous solvent included in the deactivator includes a carboxylic acid ester compound. The carboxylic acid ester compound may be, for example, one represented by formula (1). In formula (1), R 1 , R 2 are hydrocarbon groups which may be the same or different and may have a substituent. The hydrocarbon group may have, for example, a straight chain or a cyclic skeleton and may further have a substituent. The hydrocarbon group preferably has 20 or fewer carbon atoms, more preferably 15 or fewer, and may be 12 or fewer. Specific examples of the hydrocarbon group include alkyl groups and aryl groups. The alkyl group may have 1 to 8 carbon atoms, may be straight or branched, or may be a halogenated alkyl group in which some or all of the hydrogen atoms are substituted with halogen. Examples of the alkyl group include a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, and a trifluoromethyl group. The aryl group may have 6 to 12 carbon atoms. Examples of the aryl group include a phenyl group, a tolyl group, a xylyl group, a mesityl group, and a naphthyl group. Examples of the substituent include one or more of an alkyl group, an aryl group, a hydroxyl group, a sulfone group, a nitro group, an amino group, and a halogen.

[0021] [ka]

[0022] The carboxylic acid ester compound is preferably one or more of an acetic acid ester compound, a benzoic acid ester compound, and a butyric acid ester compound. Specific examples of the carboxylic acid ester compound include those represented by formulas (2) to (12). Examples of the acetic acid ester compound include octyl acetate (formula (2)), phenyl acetate (formula (3)), menthyl acetate (formula (4)), benzyl acetate (formula (5)), amyl acetate (formula (6)), hexyl acetate (formula (7)), butyl acetate (formula (8)), and derivatives thereof. Examples of the benzoic acid ester compound include ethyl benzoate (formula (9)), butyl benzoate (formula (10)), benzyl benzoate (formula (11)), and derivatives thereof. Examples of the butyric acid ester compound include butyl butyrate (formula (12)) and derivatives thereof. Of these, octyl acetate and phenyl acetate are preferred from the viewpoint of the solubility of the redox shuttle agent and the increase in the flash point.

[0023] [ka]

[0024] Furthermore, the non-aqueous solvent of the deactivator is preferably one that, when added to the electrolyte of a non-aqueous secondary battery, increases the flash point of the electrolyte. A solvent that further increases the flash point is preferable because it can further enhance safety when deactivating a non-aqueous secondary battery. For example, the carboxylic acid ester compound preferably has a higher flash point, such as 25°C or higher, more preferably 40°C or higher, even more preferably 50°C or higher, and particularly preferably 80°C or higher. The flash point of the carboxylic acid ester compound may be, for example, 200°C or lower or 150°C or lower. Furthermore, the non-aqueous solvent of the deactivator preferably increases the flash point when added to the electrolyte of a non-aqueous secondary battery, preferably by a greater degree, such as 10°C or higher, more preferably 20°C or higher, and even more preferably 30°C or higher. This degree of increase in flash point refers to the temperature difference between the flash point of the mixture of the electrolyte and the deactivator and the flash point of the electrolyte. The flash points (°C) of the formulas (2) to (12) are shown.

[0025] The deactivator may further contain a carbonate compound in addition to the carboxylic acid ester compound. When the deactivator contains a carbonate compound, for example, it may be possible to adjust the redox power of the redox shuttle agent. The carbonate compound may be the above-mentioned cyclic carbonate compound or a chain carbonate compound. When the total of the carboxylic acid ester compound and the carbonate compound is taken as 100, the carbonate compound is preferably contained in a smaller amount, preferably 50% by volume or less, more preferably 25% by volume or less, and even more preferably 10% by volume or less.

[0026] The redox shuttle agent is not particularly limited as long as it is an oxidizable and reducible compound capable of repeatedly transporting charge between a positive electrode and a negative electrode. Examples of the redox shuttle agent include one or more of ferrocene-based compounds, TEMPO-based compounds, phenothiazine-based compounds, viologen-based compounds, and quinone-based compounds. The redox shuttle agent preferably has a redox potential of less than 3.0 V relative to the lithium potential. When the current collector is made of Cu or its alloy, a redox shuttle agent having a redox potential of less than 3.0 V relative to the lithium potential is preferred because it can further suppress Cu elution. Depending on the materials of the components of the nonaqueous secondary battery, the redox shuttle agent may have a redox potential of 3.0 V or more relative to the lithium potential.

[0027] Examples of ferrocene compounds include ferrocene and its derivatives, etc. Examples of TEMPO compounds include 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO), N-(3,3,5,5-tetramethyl-4-oxypiperidyl)pyrene-1-carboxyamide (Pyrene-TEMPO), 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl radical (MeO-TEMPO), 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxybenzoate (BzO-TEMPO), and 4-acetamido-2,2,6,6-tetramethyl-1-piperidinyloxy (Ac-TEMPO).

[0028] The phenothiazine-based compound may be phenothiazine or a derivative of phenothiazine. Phenothiazine is a heterocyclic compound formed by condensing a benzene ring to each end of a thiazine. The phenothiazine-based compound may be a phenothiazine having a substituent introduced therein. The phenothiazine-based compound may be, for example, one represented by formula (13). In formula (13), R 3 ~R 11are functional groups that may be the same or different. Examples of functional groups include one or more of hydrogen, alkyl groups, aryl groups, acyl groups, alkoxy groups, alkylsulfanyl groups, hydroxyl groups, sulfone groups, nitro groups, amino groups, carboxyl groups, and halogens. The alkyl groups may have from 1 to 6 carbon atoms, may be linear or branched, or may be halogenated alkyl groups in which some or all of the hydrogen atoms are substituted with halogens. Examples of alkyl groups include methyl groups, ethyl groups, isopropyl groups, tert-butyl groups, and trifluoromethyl groups. The aryl groups may have from 6 to 12 carbon atoms. Examples of aryl groups include phenyl groups, tolyl groups, xylyl groups, mesityl groups, and naphthyl groups. The acyl groups may have from 1 to 7 carbon atoms. Examples of acyl groups include formyl groups, acetyl groups, and benzoyl groups. The alkoxy groups may have from 1 to 6 carbon atoms. Examples of alkoxy groups include methoxy groups, ethoxy groups, and phenoxy groups. The alkylsulfanyl group may have 1 to 6 carbon atoms. Examples of the alkylsulfanyl group include a methylsulfanyl group and an ethylsulfanyl group. Examples of the halogen include fluorine, chlorine, and bromine. In formula (13), R 3 ~R 11 may each independently represent a hydrogen atom, an alkyl group, a phenyl group, an acetyl group, or a halogen atom. 3 ~R 11 six or more of R may be hydrogen; 3 ~R 11Examples of the phenothiazine-based compound include phenothiazine, 2-trifluoromethylphenothiazine, 2-methoxyphenothiazine, 10-methylphenothiazine, 2-ethylthiophenothiazine, 2-methylthiophenothiazine, 2-chlorophenothiazine, 2-acetylphenothiazine, 10-ethylphenothiazine, 10-isopropylphenothiazine, 10-tert-butylphenothiazine, 10-acetylphenothiazine, 10-phenylphenothiazine, 3,7-dichloro-10-ethylphenothiazine, 3,7-dibromo-10-ethylphenothiazine, and 3,7-bis(trifluoromethyl)-10-ethylphenothiazine.

[0029] [ka]

[0030] The viologen-based compound may be a viologen or a derivative of a viologen. The viologen-based compound is a compound having a structure in which a hydrocarbon group is bonded to each of the two nitrogen atoms of the pyridine ring of a 4,4'-bipyridine skeleton, and has, for example, a structure of formula (14). In formula (14), R 12 and R 13are hydrocarbon groups that may be the same or different. The hydrocarbon group is preferably a linear or branched chain hydrocarbon group or a cyclic hydrocarbon group. Examples of the linear hydrocarbon group include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decanyl, undecanyl, and dodecanyl, and alkenyl groups such as vinyl, propenyl, butenyl, pentenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, and dodecenyl. Examples of the cyclic hydrocarbon group include cycloalkyl groups such as cyclopropyl, cyclopentyl, cyclohexyl, and cycloheptyl, and aryl groups such as phenyl and naphthyl. These hydrocarbon groups may have a substituent such as a carboxyl group, an alkoxy group, a nitro group, an amino group, or a halogen atom (e.g., F, Cl, or Br). Among these, the hydrocarbon group is preferably a linear alkyl group, and preferably one having no substituent. Each hydrocarbon group preferably has 20 or fewer carbon atoms, more preferably 10 or fewer carbon atoms, and even more preferably 6 or fewer carbon atoms. The viologen-based compound may have a structure in which a hydrocarbon group, or a substituent such as a carboxyl group, an alkoxy group, a nitro group, an amino group, or a halogen atom is introduced into one or more of the carbon atoms of the 4,4'-bipyridine skeleton. Examples of the hydrocarbon group include one or more of the hydrocarbon groups exemplified above. When the viologen-based compound has multiple substituents, the substituents may be bonded to each other to form a ring. The viologens preferably have 30 or fewer carbon atoms, more preferably 20 or fewer carbon atoms, and even more preferably 14 or fewer carbon atoms. Specific examples of the viologen-based compound include methyl viologen, ethyl viologen, propyl viologen, butyl viologen, pentyl viologen, hexyl viologen, heptyl viologen, and octyl viologen. Examples of viologen compounds include 1,1'-dimethyl-3,3'-[methylenebis(oxy)]-4,4'-bipyridinium, phenyl viologen, and 1-(4-aminophenyl)-1'-methyl-4,4'-bipyridinium.

[0031] The viologen compound has a hexafluorophosphate anion (PF6 - ), tetrafluoroborate anion (BF4 - ), pentafluoroarsine anion (AsF6 - ), perchlorate anion (ClO4 - ), Br - , Cl - , F - Inorganic anions such as trifluoromethanesulfonate (CF3SO3 - ), bis(trifluoromethanesulfonyl)imide anion (N(CF3SO2)2 - , TFSI), tris(trifluoromethylsulfonyl)methide anion (C(CF3SO2)3 - The counter anion may be the same as or different from the anion of the supporting salt of the nonaqueous secondary battery to be deactivated.

[0032] A quinone compound is a compound having a structure in which the CH groups on two carbon atoms of an aromatic hydrocarbon skeleton are each replaced with a C=O group. The quinone compound may have a 4- to 7-membered aromatic hydrocarbon skeleton, and preferably has a 6-membered aromatic hydrocarbon skeleton (a benzoquinone structure). The quinone may have, for example, a p-benzoquinone structure of formula (15) or an o-benzoquinone structure of formula (16), and preferably has a p-benzoquinone structure of formula (15). In formulas (15) and (16), R 22 ~R 25are functional groups which may be the same or different. Examples of functional groups include one or more of hydrogen, alkyl groups, aryl groups, acyl groups, alkoxy groups, alkylsulfanyl groups, hydroxyl groups, sulfonic groups, nitro groups, amino groups, carboxyl groups, and halogens. When a quinone compound has multiple substituents, the substituents may be bonded to each other to form a ring. Examples of quinone compounds in which the substituents are bonded to each other to form a ring include naphthoquinone (1,4-naphthoquinone, 1,2-naphthoquinone, etc.), anthraquinone (9,10-anthraquinone, etc.), and derivatives thereof. The quinone compound preferably has 20 or less carbon atoms, more preferably 14 or less, and even more preferably 10 or less. Specific examples of quinone compounds include p-benzoquinone, methyl-p-benzoquinone, 2,5-dimethyl-1,4-benzoquinone, methoxybenzoquinone, 2,5-dihydroxy-1,4-benzoquinone, 1,4-naphthoquinone, 2-methyl-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, anthraquinone, 2-methylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 1,4-dihydroxyanthraquinone, and 1-nitroanthraquinone.

[0033] The concentration of the redox shuttle agent contained in the deactivator is preferably higher, preferably 1.0 mmol / L or higher, more preferably 2.0 mmol / L or higher, even more preferably 2.5 mmol / L or higher, and may be 3.0 mmol / L or higher. A higher concentration of the redox shuttle agent is preferable because it allows high-energy density batteries, such as those used in electric vehicles (EVs), to be discharged in a shorter time. The concentration of the redox shuttle agent contained in the deactivator may be below the solubility limit, or may be 5.0 mol / L or lower.

[0034] The deactivator may contain solutes other than the redox shuttle agent, but preferably does not contain any solutes. Even if the deactivator contains solutes other than the redox shuttle agent, the concentration is preferably less than 0.1 mmol / L or less than 0.01 mmol / L. The lower the solute content other than the redox shuttle agent in the deactivator, the lower the viscosity tends to be, leading to more rapid deactivation. Examples of solutes include the supporting salts described above. The supporting salt may be the same as or different from the supporting salt contained in the ionically conductive medium of the nonaqueous secondary battery to be deactivated.

[0035] [Inactivation method] Next, a method for deactivating the nonaqueous secondary battery using the deactivator described above will be described. This deactivation method includes an addition step of adding the deactivator to the interior of the nonaqueous secondary battery. Specifically, the deactivator is added so that the deactivator comes into contact with the positive and negative electrodes of the nonaqueous secondary battery. The method for adding the deactivator is not particularly limited. For example, the battery container may be opened once, the deactivator may be injected, and then resealed as needed. Alternatively, the deactivator may be injected from the outside of the battery container using a syringe and then sealed as needed. The addition step is preferably performed in an inert atmosphere such as an argon atmosphere.

[0036] In this addition step, the deactivator is preferably added in an amount of 0.1 mol / Ah or less relative to the capacity of the nonaqueous secondary battery. Because the internal space of a nonaqueous secondary battery is limited, a smaller amount of deactivator is preferred. This amount may be 0.01 mol / Ah or less, or 0.005 mol / Ah or less. The amount of redox shuttle agent relative to the capacity of the nonaqueous secondary battery may be 0.001 mol / Ah or more, 0.002 mol / Ah or more, or 0.003 mol / Ah or more. Adding an amount of 0.001 mol / Ah or more is preferable because it further shortens the time required for deactivation.

[0037] The amount of the deactivator added may be appropriately selected depending on the size of the nonaqueous secondary battery, and may be, for example, 0.01 mL to 10 mL, or 0.05 mL to 5.0 mL. The amount of the deactivator added may be, for example, 0.01% to 500% or 1% to 300% of the volume [mL] of the ion conductive medium contained in the nonaqueous secondary battery to be deactivated.

[0038] The nonaqueous secondary battery containing the added deactivator may be held stationary or may be held while being vibrated. The holding time may be empirically determined as the time required for deactivation to be completed, depending on the capacity of the nonaqueous secondary battery and the amount of deactivator added. The holding time may be, for example, 6 hours to 500 hours, 30 hours to 300 hours, or 50 hours to 200 hours, depending on the capacity of the nonaqueous secondary battery and the amount of deactivator added. Furthermore, the nonaqueous secondary battery containing the added deactivator may be subjected to ultrasonic treatment. Performing ultrasonic treatment can further shorten the time it takes for the electrode composite to peel off from the current collector, which is preferable. The ultrasonic treatment is preferably performed at a frequency of, for example, 10 kHz to 120 kHz, and more preferably 30 kHz to 80 kHz. The ultrasonic treatment time depends on the size of the nonaqueous secondary battery, but is preferably 10 seconds or more, more preferably 30 seconds or more, and may be 1 minute or more. The ultrasonic treatment time may be set to 1 hour or less.

[0039] The mechanism by which this inactivation method inactivates a non-aqueous secondary battery is presumed to be as follows. Figure 2 is an explanatory diagram showing the mechanism by which a non-aqueous secondary battery is inactivated. When a redox shuttle agent (RS in the figure) that exhibits an oxidation-reduction potential lower than the positive electrode potential and higher than the negative electrode potential is added to the battery, the potential difference between the positive electrode or negative electrode and the redox shuttle agent serves as the driving force for electron transfer from the negative electrode to the redox shuttle agent and from the redox shuttle agent to the positive electrode, causing the battery to discharge. Specifically, the reduced form of the redox shuttle agent (RS in the figure) (red) ) donates electrons to the positive electrode to form the oxidized(ox) ), and the oxidized form of the redox shuttle agent receives electrons from the negative electrode to become the reduced form. This process repeats, resulting in the battery discharging. When the positive electrode potential or negative electrode potential becomes equal to the redox shuttle agent's oxidation-reduction potential, the discharge of that electrode stops. Therefore, the positive electrode potential and negative electrode potential eventually become equal to the potential of the redox shuttle agent, completing the deactivation process. Note that "deactivation is complete" may also refer to the nonaqueous secondary battery being discharged until its SOC reaches 0%. Discharging to 0% SOC prevents the negative electrode potential from being too low, for example, between 1.5 V and 3.0 V relative to the Li reference potential. This reduces the risk of gas generation due to decomposition of the electrolyte, which serves as an ion-conducting medium, and ensures the safety of the electrode itself. Therefore, recycling and disposal after deactivation can be carried out safely. A lower battery voltage after deactivation is preferable because it reduces the risk of sparks. For example, a voltage of 3.0 V or less is acceptable, with 1.2 V or less, 1.0 V or less, or 0.5 V or less being more preferred.

[0040] Furthermore, for example, when a nonaqueous secondary battery has an electrode using styrene butadiene rubber (SBR) as a binder, this deactivator can achieve peeling between the electrode composite and the current collector. The structure of styrene butadiene rubber (SBR) is shown in formula (17). As shown in formula (17), SBR is presumed to have high solubility in solvents containing linear alkyl or phenyl groups. Furthermore, the carboxylic acid ester used as the nonaqueous solvent of the deactivator is a solvent containing linear alkyl or phenyl groups, such as octyl acetate (formula (2)) or phenyl acetate (formula (3)), which is presumed to affect the binding strength of SBR. It is presumed that the SBR dissolves in the nonaqueous solution of the deactivator, weakening the binding strength of the electrode composite, resulting in the delamination of the electrode composite from the current collector.

[0041] [ka]

[0042] The deactivator and deactivation method described above can deactivate nonaqueous secondary batteries. The reason for this effect is presumed to be as follows: When a redox shuttle agent with a redox potential lower than the positive electrode potential and higher than the negative electrode potential is added to a charged nonaqueous secondary battery, the potential difference between each electrode and the redox shuttle agent serves as a driving force to discharge the battery, thereby deactivating the battery. In this case, the carboxylic acid ester compound sufficiently dissolves the redox shuttle agent and is chemically stable, allowing the redox shuttle agent to function more reliably. Furthermore, by using a nonaqueous solvent containing a carboxylic acid ester compound, it can act on, for example, the electrode binder (e.g., SBR) and promote the separation of the current collector from the electrode composite. Therefore, when disassembling the electrode components during disposal of a nonaqueous secondary battery, a separate solution can be prepared, eliminating the need for a separation process for the electrode composite, further simplifying the process. Furthermore, by using a non-aqueous solvent containing a carboxylic acid ester compound, for example, it is possible to increase the flash point of the electrolyte solution used in the non-aqueous secondary battery, thereby further improving safety when disposing of the non-aqueous secondary battery.

[0043] It goes without saying that the present disclosure is not limited to the above-described embodiments, and can be implemented in various forms as long as they fall within the technical scope of the present disclosure.

[0044] For example, in the above-described embodiment, the nonaqueous secondary battery to be deactivated has been described as a lithium ion secondary battery, but is not particularly limited thereto, and may be a hybrid capacitor, a pseudo-electric double layer capacitor, a lithium or sodium alkali metal secondary battery, an alkali metal ion battery, or the like. [Example]

[0045] Below, examples in which the deactivator and deactivation method for nonaqueous secondary batteries of the present disclosure were specifically examined are described as experimental examples. Experimental Examples 1, 4, 5, 7, and 8 correspond to examples of the present disclosure, and Experimental Examples 2, 3, and 6 correspond to comparative examples.

[0046] (Experimental Example 1) The deactivator was prepared by dissolving the redox shuttle agent phenothiazine in the solvent octyl acetate (formula (2)) at a concentration of 0.05 mol / L. The deactivation behavior of the battery due to the addition of the deactivator was evaluated. The evaluation cells were made of a negative electrode with graphite as the negative electrode active material and a LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 A lithium-ion battery was fabricated consisting of a positive electrode with O2 as the positive electrode active material. The negative electrode was made by coating a copper foil with a slurry mixture of graphite, flake graphite, carboxymethyl cellulose (CMC), and styrene butadiene rubber (SBR) in a mass ratio of 93.1:4.9:1:1 and then vacuum drying at 120°C. The positive electrode was made of LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 A slurry mixture of O2, acetylene black, and polyvinylidene fluoride (PVdF) in a mass ratio of 93:4:3 was coated on aluminum foil and vacuum dried at 120°C. The nonaqueous electrolyte solution was a 1 mol / L solution of lithium hexafluorophosphate (LiPF6) in a mixed solvent of ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) (volume ratio: 3:4:3). A polyethylene single-layer microporous membrane was used as the separator. The positive and negative electrodes were arranged facing each other with a separator impregnated with the electrolyte interposed between them and sealed in a laminate film to form an evaluation cell. This cell was subjected to two charge-discharge cycles at 20°C over a voltage range of 3.0 to 4.1 V, and then charged to 4.1 V to reach a fully charged state. The battery capacity of this evaluation cell was 17 mAh. 1.2 mL of the prepared deactivator was injected into this evaluation cell at room temperature (25°C) in an inert atmosphere (Ar) and the injection hole was sealed. The evaluation cell was placed in a thermostatic chamber at 20°C while the positive electrode composite, separator, and negative electrode composite were kept in close contact, and deactivation was performed while recording the change in voltage over time.

[0047] (Experimental Example 2) The passivation agent was prepared by dissolving 4-methoxy-2,2,6,6-tetramethylpiperidine 1-oxyl (MeO-TEMPO), a redox shuttle agent, at a concentration of 0.1 mmol / L in a solvent prepared by mixing ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a volume ratio of 3:4:3. As in Experimental Example 1, the passivation agent of Experimental Example 2 was injected into the evaluation cell, and the evaluation cell was placed in a thermostatic bath at 20°C while maintaining the positive electrode composite, separator, and negative electrode composite in close contact, and passivation was performed while recording the change in voltage over time.

[0048] (peel test) A peeling test of the negative electrode composite was conducted using the negative electrode of the evaluation cell described above and a passivator. A test specimen was prepared by sandwiching a polyethylene separator between a pair of negative electrodes and cut into a 20 mm x 5 mm piece. The test specimen was immersed in a test solution such as a passivator and left to stand for 72 hours, or after 72 hours, ultrasonic treatment was performed for 30 seconds, and the state of peeling between the current collector and the negative electrode composite layer was visually confirmed. Ultrasonic treatment was performed using a USK-3R ultrasonic wave blaster manufactured by AS ONE Corporation at a frequency of 40 kHz.

[0049] (Experimental Examples 3 and 6) The test specimen was immersed in a solution (Solution 1) prepared by dissolving 1 mol / L LiPF6 in a solvent containing EC, DMC, and EMC in a volume ratio of 3:4:3, and allowed to stand, which was used for Experimental Example 3. After the immersion and standing of Experimental Example 3, ultrasonic treatment was performed for 30 seconds, which was used for Experimental Example 6.

[0050] (Experimental Examples 4 and 7) The test specimen was immersed in a solution in which octyl acetate and Solution 1 were mixed in a volume ratio of 1:1 and allowed to stand, which was used as Experimental Example 4. After the immersion and standing of Experimental Example 4, the test specimen was subjected to ultrasonic treatment for 30 seconds, which was used as Experimental Example 7.

[0051] (Experimental Examples 5 and 8) The test specimen was immersed in a solution in which phenyl acetate and Solution 1 were mixed in a volume ratio of 1:1 and allowed to stand, which was used as Experimental Example 5. After the immersion and standing of Experimental Example 5, the test specimen was subjected to ultrasonic treatment for 30 seconds, which was used as Experimental Example 8.

[0052] (Flash point calculation) The flash point was calculated by the following procedure. 1. The vapor pressures of DMC and octyl acetate at their flash points were calculated using the Antoine equation. 2. The partial vapor pressures of DMC and octyl acetate were calculated at various temperatures by changing the molar ratio of DMC to octyl acetate. 3. The partial vapor pressure of DMC for each composition calculated below the flash point of octyl acetate was compared with the vapor pressure at the flash point of DMC to calculate the composition with the equivalent vapor pressure, and this was used as the flash point for that composition.

[0053] (Results and Discussion) Figure 3 shows the discharge behavior after adding the passivators of Experimental Examples 1 and 2 to a fully charged evaluation cell. Figure 4 is a photograph showing an example of the peeling state of the electrode composite in Experimental Examples 3 to 5. Figure 5 is a photograph showing the peeling state of the electrode composite after ultrasonic treatment in Experimental Examples 6 to 8. As shown in Figure 3, in Experimental Example 2, the voltage remained above 4 V even after the passage of time, indicating that passivation had hardly progressed. In contrast, in Experimental Example 1, the voltage reached 0 V, indicating that passivation had progressed sufficiently. Also, as shown in Figure 4, in Experimental Example 3, even after 72 hours of standing, a black electrode composite was formed on the copper foil, indicating that the electrode composite had not peeled off. On the other hand, in Experimental Examples 4 and 5, the black electrode composite was observed in the solution, indicating that the electrode composite had peeled off. Also, as shown in Figure 5, in Experimental Example 6, the electrode composite did not peel off even after ultrasonic treatment after standing. On the other hand, in Experimental Examples 7 and 8, the electrode composite peeling was further promoted by ultrasonic treatment after standing. In this way, it was found that the use of a deactivator containing a redox shuttle agent and a carboxylic acid ester compound can deactivate the secondary battery and accelerate the peeling of the electrode mixture.

[0054] Considering the delamination of the electrode composite, as shown in equations (2), (3), and (17), the molecular structures of SBR, octyl acetate, and phenyl acetate suggest that SBR has high solubility in solvents containing linear alkyl or phenyl groups. Therefore, it is presumed that the SBR dissolves in the solution, weakening the binding strength of the active material, resulting in delamination. In a lithium-ion battery constructed using a similar negative electrode composite, the negative electrode composite faces the positive electrode composite across the separator, forming a tightly packed state. Therefore, it is presumed that it takes longer for the added solution to penetrate and mix with the electrolyte present before deactivation to form a homogeneous solution. However, once mixed, the state is similar to that in this delamination experiment, and therefore it is presumed that the same delamination effect can be obtained. In addition, carboxylic acid ester compounds such as acetic acid-based solvents include those that have linear chains of different lengths, such as ethyl acetate and amyl acetate, and those that have cyclic carbon chains, such as menthyl acetate. It was presumed that a similar peeling effect would be obtained when these solvents were used as solvents for the deactivator (Equations (2) to (12)).

[0055] The above mechanism can be considered using the Hansen Solubility Parameter (HSP), which quantifies molecular similarity. HSP is a parameter used as an indicator of the solubility of a compound. The dispersion force δD, polarization force δP, and hydrogen bonding force δH are determined experimentally or by calculation for each core substance, and the solubility is estimated or determined based on the distance between compounds in Hansen space, a three-dimensional orthogonal space with δD, δP, and δH as its axes. The HSP of a mixed solvent is also represented by the volume average of each solvent being mixed. The HSP of SBR, for example, is δD = 18.0 MPa, as described in Reference 1 (Polym.Test., 81, (2020), 106253.). 1 / 2 , δP=2.9MPa 1 / 2 , δH=2.3MPa 1 / 2 On the other hand, for carbonate-based solvents used in lithium-ion secondary batteries, the DMC is δD = 15.5 MPa, according to reference 2 (Solubility Science; Principles and Practice, Version 1.0.2.1a, March 2021, Steven Abbott.).1 / 2 , δP=8.6MPa 1 / 2 , δH=9.7MPa 1 / 2 and EC is δD = 18.0 MPa. 1 / 2 , δP=21.7MPa 1 / 2 , δH=5.1MPa 1 / 2 Considering the solubility and dissociation of lithium salts, this solvent has higher δP and δH than SBR. On the other hand, octyl acetate has δD = 15.8 MPa 1 / 2 , δP=2.9MPa 1 / 2 , δH=5.1MPa 1 / 2 It was inferred that adding a deactivator to the electrolyte solution would lower both δP and δH. In this way, it was inferred that adding a deactivator to the electrolyte solution would bring the HSP of the SBR and the mixed solution closer together in the Hansen space, causing the SBR to swell or dissolve, weakening the binding strength of the electrode composite. In addition, phenyl acetate has a δD of 19.8 MPa. 1 / 2 , δP=5.2MPa 1 / 2 , δH=6.4MPa 1 / 2 It was speculated that the same effect as that of octyl acetate could be expected.

[0056] Table 1 shows the molecular weight of DMC (90 g / mol, density 1.07 g / cm 3 ) and octyl acetate (molecular weight 172.3 g / mol, density 0.87 g / cm 3The calculated flash points of mixed solvents of DMC and octyl acetate are summarized below. The flash point of octyl acetate is 86°C, and in mixed solvents of DMC and octyl acetate at temperatures below 60°C in Table 1, the flash point was always higher than that of DMC. Furthermore, regardless of the mixing ratio, the flash point increased monotonically with decreasing DMC content. When DMC and octyl acetate were mixed in equal volumetric ratios, the flash point was expected to increase by approximately 10°C compared to the flash point of DMC (16°C). This is comparable to the approximately 10°C difference in the flash point of DMC reported in Reference 3 (J. Electrochem. Soc. 162 A3084.) between that of a 1:1 volumetric mixture of DMC and EC, and is therefore reasonable. Furthermore, for example, if a solvent containing a 3:4:3 mixture of EC, DMC, and EMC is used as the electrolyte, and an equal amount of deactivator is added to the electrolyte present inside the battery, the volume ratio of DMC, which has the lowest flash point among the solutions present inside the battery, will be 20% or less or 15% or less, and the flash point will be estimated to be 30°C or higher or 40°C or higher.

[0057] From the above, it was found that using a carboxylic acid ester compound as the nonaqueous solvent of the deactivator can more reliably deactivate nonaqueous secondary batteries, further promoting the exfoliation of the electrode composite, and increasing the flash point of the electrolyte, thereby improving safety. It was inferred that the electrode composite is preferably exfoliated using electrodes containing styrene butadiene rubber (SBR) as a binder, and that ultrasonic treatment of the nonaqueous secondary battery is preferable. It was also inferred that similar effects can be achieved with carboxylic acid ester compounds, such as benzoic acid ester compounds and butyric acid ester compounds, in addition to acetate ester compounds. The redox shuttle agent is not particularly limited, and it was inferred that similar effects can be achieved with phenothiazine-based compounds, ferrocene-based compounds, TEMPO-based compounds, viologen-based compounds, and quinone-based compounds. It was also inferred that the deactivator may further contain a carbonate compound in addition to the carboxylic acid ester compound.

[0058] [Table 1]

[0059] It goes without saying that the present disclosure is not limited to the above-described embodiments, and can be implemented in various forms as long as they fall within the technical scope of the present disclosure. [Industrial Applicability]

[0060] The present invention is applicable to the field of the battery industry. [Explanation of symbols]

[0061] 20 non-aqueous secondary battery, 21 battery case, 22 positive electrode, 23 negative electrode, 24 separator, 25 gasket, 26 sealing plate, 27 ion conductive medium.

Claims

1. A deactivator for deactivating a non-aqueous secondary battery, a redox shuttle agent having an oxidation-reduction potential, relative to a Li reference potential, higher than that of a negative electrode active material of the nonaqueous secondary battery and lower than that of a positive electrode active material of the nonaqueous secondary battery; a non-aqueous solvent containing a carboxylic acid ester compound; The carboxylic acid ester compound is a deactivating agent represented by any one of formulas (1) to (11). 【Chemistry 1】

2. The deactivator according to claim 1 , wherein the non-aqueous solvent increases the flash point of the electrolyte solution of the non-aqueous secondary battery when added to the electrolyte solution.

3. The deactivator according to claim 1 or 2, wherein the redox shuttle agent is one or more of a ferrocene-based compound, a TEMPO-based compound, a phenothiazine-based compound, a viologen-based compound, and a quinone-based compound.

4. The deactivating agent according to any one of claims 1 to 3, further comprising a carbonate compound in addition to the carboxylic acid ester compound.

5. A method for deactivating a non-aqueous secondary battery, comprising: an addition step of adding the deactivator for a non-aqueous secondary battery according to any one of claims 1 to 4 to the inside of the non-aqueous secondary battery; An inactivation method comprising:

6. The deactivation method according to claim 5 , wherein the adding step adds the deactivator to the nonaqueous secondary battery having electrodes containing styrene-butadiene rubber as a binder.

7. The deactivation method according to claim 5 or 6, wherein the adding step comprises subjecting the nonaqueous secondary battery to an ultrasonic treatment.

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