Electrode manufacturing method

Abstract

To provide a manufacturing method of an electrode, in which a gelatinization of a mixture containing a vinylidene fluoride polymer.SOLUTION: The present invention relates to a manufacturing method of an electrode, that a vinylidene fluoride polymer containing 50 mol% or more in a vinylidene fluoride unit and an electrode mixture containing an Oxime and an active material are coated to a collector body, the electrode mixture is dried to obtain an electrode mixture layer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing an electrode, an electrode, and a non-aqueous electrolyte secondary battery. [Background technology]

[0002] Vinylidene fluoride polymers, which mainly contain repeating units derived from vinylidene fluoride, are widely used as binder resins for batteries such as lithium-ion secondary batteries. Binder resins are used to adhere active materials to current collectors.

[0003] To increase the capacity of batteries, batteries using ternary positive electrode active materials with a high nickel ratio are being considered. However, because ternary positive electrode active materials contain a large amount of base, they tend to accelerate the deterioration of binder compositions containing vinylidene fluoride polymers. This deterioration causes the slurry-like electrode mixture (hereinafter also referred to as electrode mixture slurry) to thicken and eventually gel. It is difficult to apply the gelled electrode mixture slurry to a current collector. Therefore, in batteries using ternary positive electrode active materials, the electrode mixture is required to have higher gelation resistance.

[0004] For example, Patent Document 1 describes a binder composition containing a copolymer having a first constituent unit derived from vinylidene fluoride and an isocyanate group or a structural unit having a structure that generates an isocyanate group when heated. It also describes that the binder composition is resistant to gelation even when stored for a long period of time.

[0005] Patent Document 2 describes a conductive paste for a lithium-ion battery positive electrode, which contains a dispersion resin, polyvinylidene fluoride, conductive carbon, a solvent, and a polymerization inhibitor. It also describes that the paste has high viscosity and is inhibited from gelling. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-160675 [Patent Document 2] Japanese Patent Application Publication No. 2017-228412 Summary of the Invention [Problem to be solved by the invention]

[0007] However, even the binder compositions and conductive pastes described in Patent Documents 1 and 2 do not provide sufficient resistance to gelation of the electrode mixture, and there is a need to develop a binder that suppresses gelation of the electrode mixture.

[0008] The present invention has been made in view of the problems of the prior art described above, and has an object to provide a binder that suppresses gelation of an electrode mixture more effectively than conventional binders. [Means for solving the problem]

[0009] As a result of extensive research to solve the above-mentioned problems, the present inventors have unexpectedly found that gelation of an electrode mixture can be suppressed by using a binder containing a vinylidene fluoride polymer and an oxime in the electrode mixture, and have thus arrived at the present invention.

[0010] That is, a binder according to one embodiment of the present invention contains a vinylidene fluoride polymer containing 50 mol % or more of vinylidene fluoride units and an oxime. [Effects of the Invention]

[0011] According to one aspect of the present invention, it is possible to provide a binder that suppresses gelation of an electrode mixture. DETAILED DESCRIPTION OF THE INVENTION

[0012] (binder) The binder according to this embodiment contains a vinylidene fluoride polymer and an oxime, and is used as a binder for binding the electrode active material onto the current collector.

[0013] The binder of this embodiment contains an oxime, which can suppress gelation of the electrode mixture. That is, the binder of this embodiment has high gelation resistance. For example, when the viscosity of the electrode mixture increases compared to the viscosity immediately after preparation, it can be determined that gelation is progressing.

[0014] (vinylidene fluoride polymer) In this specification, the term "vinylidene fluoride polymer" includes both a homopolymer of vinylidene fluoride and a copolymer of vinylidene fluoride and a monomer copolymerizable with vinylidene fluoride. The monomer copolymerizable with vinylidene fluoride can be appropriately selected from known monomers, for example. When vinylidene fluoride is copolymerized, the copolymer contains vinylidene fluoride as the main constituent. Specifically, the copolymer contains 50 mol% or more of vinylidene fluoride units, preferably 80 mol% or more of vinylidene fluoride units, and more preferably 90 mol% or more of vinylidene fluoride units.

[0015] When the vinylidene fluoride polymer is a copolymer, it is preferably a vinylidene fluoride polymer containing vinylidene fluoride as a main constituent component and containing a structural unit represented by the following formula (3). [ka]

[0016] In formula (3), R4 is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a carboxyl group substituted with an alkyl group having 1 to 5 carbon atoms, and R5 and R6 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. From the viewpoint of the polymerization reaction, it is particularly desirable that R4 and R5 are substituents with little steric hindrance, and hydrogen or an alkyl group having 1 to 3 carbon atoms is preferred, and hydrogen or a methyl group is more preferred.

[0017] In formula (3), X is a single bond or an atomic group whose main chain has 1 to 20 atoms and a molecular weight of 500 or less. The molecular weight of the atomic group is preferably 200 or less. There is no particular lower limit to the molecular weight of the atomic group, but it is usually 15. When the molecular weight of the atomic group is within the above range, gelation of the electrode mixture slurry can be suitably suppressed. Here, the "number of atoms in the main chain" refers to the number of atoms in the skeleton part of the chain connecting the carboxyl group described to the right of X in formula (3) and the group (R4R5C=CR6-) described to the left of X with the fewest number of atoms. X may be branched by including a functional group as a side chain. X may include one or more side chains. When X is a single bond, the compound in formula (3) has a structure in which the carboxyl group is directly bonded to the carbon atom bonded to R6.

[0018] Examples of compounds having the structural unit represented by formula (3) include acrylic acid (AA), methacrylic acid, 2-carboxyethyl acrylate (CEA), 2-carboxyethyl methacrylate, maleic acid monomethyl ester, acryloyloxyethyl succinate (AES), acryloyloxypropyl succinate (APS), methacryloyloxyethyl succinate, and methacryloyloxypropyl succinate.

[0019] The vinylidene fluoride polymer may have, as a structural unit, a component of a compound other than vinylidene fluoride and the structural unit represented by formula (3). Examples of such other compounds include vinyl fluoride, trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene (HFP), and perfluoroalkyl vinyl ethers, such as perfluoromethyl vinyl ether; and (meth)acrylate monomers not having a COOH group at the terminal, such as glycidyl (meth)acrylate and methyl (meth)acrylate.

[0020] When the vinylidene fluoride polymer is a copolymer, the modification amount (structural unit represented by formula (3) in the vinylidene fluoride polymer) is preferably 0.01 to 10 mol%, more preferably 0.1 to 5 mol%, and even more preferably 0.2 to 1 mol%. Furthermore, the vinylidene fluoride polymer preferably contains 90 to 99.99 mol%, more preferably 95 to 99.90 mol%, even more preferably 99.00 to 99.80 mol%, and particularly preferably 99.50 to 99.80 mol% of vinylidene fluoride-derived structural units. By having the structural unit represented by formula (3) in the above range, the change in viscosity of the electrode mixture after storage relative to the viscosity of the electrode mixture immediately after preparation is small, and an electrode mixture with a stable viscosity can be obtained.

[0021] The amount of vinylidene fluoride units in the vinylidene fluoride polymer and the amount of the structural unit represented by formula (3) are 1 H NMR spectrum or 19 It can be determined by F NMR spectroscopy or neutralization titration.

[0022] (Example of vinylidene fluoride polymer) Commercially available vinylidene fluoride polymers can be used, such as KF#7300, KF#9100, KF#9700, KF#7500, and KF#9400 manufactured by Kureha Corporation.

[0023] (Inherent viscosity (ηi) of vinylidene fluoride polymer) The inherent viscosity of the vinylidene fluoride polymer used in this embodiment is not particularly limited, but is preferably 0.5 to 5.0 dL / g, more preferably 1.0 dL / g or more and 4.5 dL / g or less, and even more preferably 1.5 dL / g or more and 4.0 dL / g or less. If the inherent viscosity is in the above range, it is preferable in that it does not cause unevenness in the thickness of the electrode when the electrode mixture slurry is applied, and electrode production can be easily performed.

[0024] The inherent viscosity (ηi) is calculated, for example, as follows. A polymer solution is prepared by dissolving 80 mg of vinylidene fluoride polymer in 20 mL of N,N-dimethylformamide. The viscosity η of the prepared polymer solution is measured using an Ubbelohde viscometer in a thermostatic bath at 30°C. The inherent viscosity (ηi) is then calculated from the following formula: i ) is calculated. η i =(1 / C)·ln(η / η0) In the above formula, η0 is the viscosity of the solvent N,N-dimethylformamide, and C is the concentration of vinylidene fluoride polymer in the prepared polymer solution (0.4 g / dL).

[0025] (Polymerization method for vinylidene fluoride polymer) The polymerization method for vinylidene fluoride polymers is not particularly limited, and any conventionally known polymerization method can be used. Examples of the polymerization method include suspension polymerization, emulsion polymerization, solution polymerization, etc. Among these, aqueous suspension polymerization or emulsion polymerization is preferred from the viewpoint of ease of post-treatment, and aqueous suspension polymerization is particularly preferred.

[0026] (oxime) The oxime contained in the binder of this embodiment is a compound in which the oxygen atom of the carbonyl group of an aldehyde or ketone is substituted with a hydroxyimino group (=NOH). That is, there are aldehyde-derived oximes (RCH=NOH) and ketone-derived oximes (R'RC=NOH).

[0027] An example of an oxime is a compound represented by formula (1). [ka]

[0028] In formula (1), R1 and R2 are each independently selected from a hydrogen atom, an aldehyde group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, an aryl group having 6 to 18 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, or a heterocyclic group having 3 to 13 carbon atoms, and some or all of the hydrogen atoms in these groups may be substituted with a substituent selected from an alkyl group having 1 to 10 carbon atoms, an aryl group, a hydroxyl group, and an amino group, and R1 and R2 may be bonded to each other to form a ring together with the carbon atoms to which R1 and R2 are bonded.

[0029] In formula (1), the alkyl group has 1 to 10 carbon atoms, preferably 1 to 5, and more preferably 1 to 2. The alkenyl group has 2 to 10 carbon atoms, preferably 2 to 6, and more preferably 2 to 4. The alkynyl group has 2 to 10 carbon atoms, preferably 2 to 6, and more preferably 2 to 4. The cycloalkyl group has 3 to 10 carbon atoms, preferably 3 to 7, and more preferably 5 to 7. The aryl group has 6 to 18 carbon atoms, preferably 6 to 10, and more preferably 6 to 8. The aralkyl group has 7 to 14 carbon atoms, preferably 7 to 11, and more preferably 7 to 9. The heterocyclic group has 3 to 13 carbon atoms, preferably 3 to 10, and more preferably 3 to 8.

[0030] In formula (1), when R1 and R2 are bonded to each other to form a ring together with the carbon atom to which R1 and R2 are bonded, the ring may be an aromatic ring or a non-aromatic ring. Furthermore, the compound represented by formula (1) may be a conjugated compound. The ring may be a 3- to 12-membered ring, preferably a 3- to 8-membered ring. When such a ring is formed, a compound represented by HO-N=R3 is preferred, where R3 is a cycloalkyl group having 3 to 8 carbon atoms. The hydrogen atom of the cycloalkyl group may be substituted with an alkyl group having 1 to 10 carbon atoms.

[0031] Compounds represented by formula (1) include acetone oxime (acetoxime), 2-butanone oxime (methyl ethyl ketone oxime), methyl isopropyl ketone oxime, methyl tertiary butyl ketone oxime, ditertiary butyl ketone oxime, 2-pentanone oxime, 3-pentanone oxime, 1-cyclohexyl-1-propanone oxime, acetaldoxime (acetaldehyde oxime), benzaloxime (benzaldehyde oxime), acetophenone oxime, benzophenone oxime, and 4-hydroxyacetophenone oxime. oxime, cyclopropanone oxime, cyclobutanone oxime, cyclopentanone oxime, cyclohexanone oxime, cycloheptanone oxime, cyclooctanone oxime, cyclononanone oxime, cyclodecanone oxime, cyclododecanone oxime, benzoquinone dioxime, benzoquinone monooxime, 2,3-butanedione monooxime, acetamide oxime, 3-hydroxy-3-methyl-2-butanone oxime, α-benzoin oxime, 1,3-dihydroxyacetone oxime, and 2-isonitrosopropiophenone.

[0032] In the binder of this embodiment, in terms of high gelation resistance and the like, it is preferable that R1 and R2 in the compound represented by formula (1) are each independently selected from a hydrogen atom, an aryl group having 6 to 18 carbon atoms, an aldehyde group, or an alkyl group having 1 to 10 carbon atoms. Some or all of the hydrogen atoms in these groups may be substituted with a substituent selected from an alkyl group having 1 to 10 carbon atoms, an aryl group, a hydroxyl group, and an amino group. Furthermore, when R1 and R2 are alkyl groups, R1 and R2 may be bonded to each other to form a ring together with the carbon atoms to which R1 and R2 are bonded. Examples of preferred compounds represented by formula (1) include acetoxime, 2-butanone oxime, cyclohexanone oxime, acetaldehyde oxime, benzaldehyde oxime, and 2,3-butanedione monooxime.

[0033] In the binder of this embodiment, from the viewpoint of high gelation resistance and the like, it is more preferable that R1 and R2 in the compound represented by formula (1) are each independently selected from alkyl groups having 1 to 10 carbon atoms. Some or all of the hydrogen atoms in these groups may be substituted with substituents selected from alkyl groups having 1 to 10 carbon atoms, aryl groups, hydroxyl groups, and amino groups. Furthermore, when R1 and R2 are alkyl groups, R1 and R2 may be bonded to each other to form a ring together with the carbon atoms to which R1 and R2 are bonded. Examples of more preferable embodiments of the compound represented by formula (1) include acetoxime, 2-butanone oxime, and cyclohexanone oxime.

[0034] An example of an oxime is a compound represented by formula (2). [ka]

[0035] In formula (2), R7 and R8 are each independently selected from a hydrogen atom, an aldehyde group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, an aryl group having 6 to 18 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, or a heterocyclic group having 3 to 13 carbon atoms, and some or all of the hydrogen atoms in these groups may be substituted with a substituent selected from an alkyl group having 1 to 10 carbon atoms, an aryl group, a hydroxyl group, and an amino group, and R7 and R8 may be bonded to each other to form a ring together with the carbon atom to which R7 is bonded and the carbon atom to which R8 is bonded.

[0036] Examples of the compound represented by formula (2) include dimethylglyoxime, methylethylglyoxime, diethylglyoxime, and diphenylglyoxime.

[0037] Preferred embodiments of the substituents (R7 and R8) in formula (2) are the same as the preferred embodiments of the substituents (R1 and R2) in formula (1). Preferred examples of the compound represented by formula (2) include dimethylglyoxime.

[0038] Examples of oximes include polymers containing hydroxyimino groups (hereinafter sometimes referred to as "oxime polymers") and oligomers containing hydroxyimino groups (hereinafter sometimes referred to as "oxime oligomers"). Oxime polymers and oxime oligomers have low volatility, which allows the binder to be stored for a long period of time compared to when low-molecular-weight oximes are used.

[0039] Oxime polymers or oxime oligomers can be synthesized by polymerizing a monomer or oligomer containing a hydroxyimino group, or by reacting a polymer or oligomer having a ketone group in the backbone with hydroxyamine. Examples of polymers having a ketone group in the backbone include poly(methyl vinyl ketone), polyketone (PK), polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), polyether ether ketone ketone (PEEKK), and polyether ketone ether ketone ketone (PEKEKK).

[0040] Examples of oxime polymers or oxime oligomers include poly(methylvinyloxime).

[0041] The above oximes may be used alone or in combination of two or more.

[0042] The binder preferably contains 0.005 to 5 mmol of oxime per 1 g of vinylidene fluoride polymer, more preferably 0.1 to 5 mmol, and even more preferably 0.25 to 5 mmol. The binder also preferably contains 0.005 to 5 mmol of hydroxyimino groups of the oxime per 1 g of vinylidene fluoride polymer, more preferably 0.1 to 5 mmol, and even more preferably 0.25 to 5 mmol.

[0043] The form of the binder in this embodiment is not particularly limited and may be powder or liquid. The binder may also contain a solvent. The solvent may be a non-aqueous solvent or water. Examples of non-aqueous solvents include N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoamide, dioxane, tetrahydrofuran, tetramethylurea, triethyl phosphate, trimethyl phosphate, acetone, ethyl acetate, n-butyl acetate, n-butanol, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and cyclohexanone. Two or more of these solvents may be mixed and used.

[0044] [Electrode mixture] The electrode mixture of this embodiment contains the binder and an active material. The electrode mixture may also contain a conductive aid, a non-aqueous solvent, a pigment dispersant, a dispersion stabilizer, and the like.

[0045] The electrode mixture can be used as an electrode mixture for a positive electrode or a negative electrode by changing the type of active material etc. depending on the type of current collector to be coated etc. Since vinylidene fluoride polymers generally have excellent oxidation resistance, the electrode mixture of this embodiment is preferably used as an electrode mixture for a positive electrode.

[0046] (active material) Lithium metal oxide is typically used as the positive electrode active material. The positive electrode active material may contain, in addition to lithium metal oxide, impurities, additives, etc. The types of impurities, additives, etc. contained in the positive electrode active material are not particularly limited.

[0047] Examples of lithium metal oxides include LiMnO2, LiMn2O4, LiCoO2, LiNiO2, and LiNi x Co 1-x O2(0 <x<1)、LiNi x Co y Mn 1-x-yO2(0 < x < 1, 0 < y < 1), LiNi x Co y Al 1-x-y Examples thereof include O2(0 < x < 1, 0 < y < 1), LiFePO4, etc.

[0048] It is preferable that the lithium metal oxide contains Ni in that it can increase the capacity density of the secondary battery, thereby increasing its capacity. Further, it is preferable that the lithium metal oxide contains Co in addition to Ni in that it exhibits stable cycle characteristics due to suppression of crystal structure changes during charge and discharge processes.

[0049] Preferred lithium metal oxides include lithium metal oxides (ternary lithium metal oxides) represented by the following formula (4). Ternary lithium metal oxides are particularly preferably used as electrode active materials in this embodiment because they have a high charging potential and excellent cycle characteristics. LiNi x Co y M z O2 ···(4) (In the formula, M is Mn or Al, and 0 < x ≤ 1, 0 < y ≤ 1, 0 < z ≤ 1)

[0050] Specific examples of preferred lithium metal oxides include Li 1.00 Ni 0.5 Co 0.2 Mn 0.3 O2 (NCM523), Li 1.00 Ni 0.6 Co 0.2 Mn 0.2 O2 (NCM622), Li 1.00 Ni 0.83 Co 0.12 Mn 0.05 O2 (NCM811), and Li 1.00 Ni 0.85 Co 0.15 Al 0.05O2 (NCA811). These preferred lithium metal oxides have a pH of 10.5 or higher when extracted with water. The extraction is performed at room temperature (25°C) using the extraction method specified in JIS K 5101-16-2.

[0051] Specifically, the pH value is obtained by adding the electrode active material to ultrapure water in an amount 50 times the weight of the electrode active material, stirring the mixture with a magnetic stirrer at a rotation speed of 600 rpm for 10 minutes, and measuring the pH of the resulting solution using a pH meter Model F-21 manufactured by Horiba, Ltd.

[0052] An electrode mixture slurry containing a positive electrode active material in which the pH of the water is at least 10.5 or higher contains a large amount of base, and therefore the electrode mixture is prone to deterioration. As a result, the electrode mixture slurry is prone to thickening. To prevent the thickening of the electrode mixture slurry, it is necessary to remove the base by washing the positive electrode active material with water. However, since the electrode mixture of this embodiment contains an oxime, thickening of the electrode mixture slurry (gelling of the electrode mixture) is prevented even when a positive electrode active material containing a large amount of base is used. Therefore, since the electrode mixture of this embodiment contains an oxime, there is no need to wash the positive electrode active material with water.

[0053] The negative electrode active material can be any conventionally known material, including carbon materials, metal or alloy materials, metal oxides, etc. Among these, carbon materials are preferred from the viewpoint of further increasing the energy density of the battery, and examples of carbon materials include artificial graphite, natural graphite, non-graphitizable carbon, and easily graphitizable carbon.

[0054] In the electrode mixture, when the amount of the active material is taken as 100 parts by mass, the vinylidene fluoride polymer is preferably contained in an amount of 0.2 to 15 parts by mass, more preferably 0.5 to 10 parts by mass.

[0055] The electrode mixture preferably contains 0.01 to 10 mmol of oxime, more preferably 0.2 to 10 mmol, and even more preferably 0.5 to 10 mmol, per 100 g of active material, and preferably contains 0.01 to 10 mmol of hydroxyimino groups contained in the oxime, more preferably 0.2 to 10 mmol, and even more preferably 0.5 to 10 mmol, per 100 g of active material.

[0056] (Conductive additive) The conductive additive may be added to improve the conductivity of the electrode mixture layer when an active material with low electronic conductivity, such as LiCoO2, is used. Examples of the conductive additive include carbonaceous materials such as carbon black, carbon nanotubes, graphite fine powder, and graphite fiber, as well as metal fine powders or metal fibers such as nickel and aluminum.

[0057] (non-aqueous solvent) The non-aqueous solvent may be any of those exemplified as non-aqueous solvents that can be contained in the binder, such as N-methylpyrrolidone (NMP), etc. The non-aqueous solvent may be used alone or in combination of two or more.

[0058] (Other components of electrode mixture) The electrode mixture of this embodiment may contain other components in addition to the above-mentioned components, such as a pigment dispersant such as polyvinylpyrrolidone.

[0059] (Preparation of electrode mixture) The electrode mixture according to this embodiment may be prepared by, for example, mixing a binder containing a vinylidene fluoride polymer and an oxime with an active material to form a uniform slurry, and the order of mixing is not particularly limited. Furthermore, when a binder containing a solvent is used as the binder, the electrode active material and the like may be added before adding the solvent to the binder. For example, the electrode active material may be added to the binder, and then the solvent may be added, followed by stirring and mixing to obtain an electrode mixture. Alternatively, the electrode active material may be dispersed in a solvent, to which the binder is added, followed by stirring and mixing to obtain an electrode mixture. Alternatively, the electrode active material may be added to a binder containing a solvent as the binder, followed by stirring and mixing to obtain an electrode mixture.

[0060] Alternatively, the electrolyte can be prepared by mixing the oxime with the active material and then mixing the vinylidene fluoride polymer.

[0061] 〔electrode〕 The electrode according to this embodiment includes an electrode mixture layer formed from the electrode mixture on a current collector. Unless otherwise specified, the term "electrode" in this specification and the like refers to a battery electrode in which an electrode mixture layer formed from the electrode mixture of this embodiment is formed on a current collector.

[0062] (current collector) The current collector is the base material of the electrode and a terminal for extracting electricity. Examples of materials for the current collector include iron, stainless steel, steel, copper, aluminum, nickel, and titanium. The current collector is preferably in the form of a foil or mesh. When the electrode is a positive electrode, the current collector is preferably an aluminum foil. The thickness of the current collector is preferably 5 μm to 100 μm, and more preferably 5 to 20 μm.

[0063] (Electrode mixture layer) The electrode mixture layer is a layer obtained by applying the above-described electrode mixture to a current collector and drying it. The electrode mixture can be applied by any method known in the art, including methods using a bar coater, die coater, or comma coater. The drying temperature for forming the electrode mixture layer is preferably 50°C to 170°C, and more preferably 50°C to 150°C. The electrode mixture layer may be formed on both sides of the current collector, or on only one side.

[0064] The thickness of the electrode mixture layer is usually 20 to 600 μm per side, preferably 20 to 350 μm. The electrode mixture layer may be pressed to increase its density. The basis weight of the electrode mixture layer is usually 20 to 700 g / m 2 and preferably 30 to 500 g / m 2 is.

[0065] As described above, the electrode becomes a positive electrode when an electrode mixture layer is obtained using an electrode mixture for a positive electrode, and becomes a negative electrode when an electrode mixture layer is obtained using an electrode mixture for a negative electrode. The electrode according to this embodiment can be used as a positive electrode of a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery.

[0066] [Nonaqueous electrolyte secondary battery] The nonaqueous electrolyte secondary battery of this embodiment includes the above-described electrode. Other components in the nonaqueous electrolyte secondary battery are not particularly limited, and for example, conventionally used components can be used.

[0067] A method for manufacturing a nonaqueous electrolyte secondary battery includes, for example, stacking a negative electrode layer and a positive electrode layer with a separator interposed therebetween, placing the stacked negative electrode layer and positive electrode layer in a battery container, injecting an electrolyte solution into the battery container, and sealing the battery container. In this manufacturing method, by hot pressing after injecting the electrode solution, at least a portion of the vinylidene fluoride polymer contained in the electrode mixture is melted and adhered to the separator.

[0068] 〔summary〕 The binder according to this embodiment contains a vinylidene fluoride polymer containing 50 mol % or more of vinylidene fluoride units and an oxime.

[0069] In the binder according to the present embodiment, the oxime is preferably at least one oxime selected from a compound represented by the following formula (1), a compound represented by the following formula (2), and a polymer or oligomer having a hydroxyimino group: [ka] [ka] In the formula (1), R1 and R2 are each independently selected from a hydrogen atom, an aldehyde group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, an aryl group having 6 to 18 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, or a heterocyclic group having 3 to 13 carbon atoms, and some or all of the hydrogen atoms of these groups may be substituted with a substituent selected from an alkyl group having 1 to 10 carbon atoms, an aryl group, a hydroxyl group, and an amino group, and R1 and R2 may be bonded to each other to form a ring together with the carbon atom to which R1 and R2 are bonded, and wherein R7 and R8 are each independently selected from a hydrogen atom, an aldehyde group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, an aryl group having 6 to 18 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, or a heterocyclic group having 3 to 13 carbon atoms, wherein some or all of the hydrogen atoms of these groups may be substituted with a substituent selected from an alkyl group having 1 to 10 carbon atoms, an aryl group, a hydroxyl group, and an amino group, and R7 and R8 may be bonded to each other to form a ring together with the carbon atom to which R7 is bonded and the carbon atom to which R8 is bonded.

[0070] In the binder according to the present embodiment, in the formula (1), R1 and R2 are each independently selected from a hydrogen atom, an aryl group having 6 to 18 carbon atoms, an aldehyde group, or an alkyl group having 1 to 10 carbon atoms, and some or all of the hydrogen atoms of these groups may be substituted with a substituent selected from an alkyl group having 1 to 10 carbon atoms, an aryl group, a hydroxyl group, and an amino group. When R1 and R2 are alkyl groups, R1 and R2 are bonded to each other to form a ring together with the carbon atoms to which R1 and R2 are bonded. In the formula (2), R7 and R8 are each independently selected from a hydrogen atom, an aryl group having 6 to 18 carbon atoms, an aldehyde group, or an alkyl group having 1 to 10 carbon atoms, and some or all of the hydrogen atoms in these groups may be substituted with a substituent selected from an alkyl group having 1 to 10 carbon atoms, an aryl group, a hydroxyl group, and an amino group. When R7 and R8 are alkyl groups, R7 and R8 may be bonded to each other to form a ring together with the carbon atom to which R7 is bonded and the carbon atom to which R8 is bonded.

[0071] Furthermore, in the binder according to the present embodiment, in the formula (1), R1 and R2 are each independently selected from alkyl groups having 1 to 10 carbon atoms, and when R1 and R2 are alkyl groups, R1 and R2 may be bonded to each other to form a ring together with the carbon atoms to which R1 and R2 are bonded; and in the formula (2), R7 and R8 are each independently selected from hydrogen atoms or alkyl groups having 1 to 10 carbon atoms, and when R7 and R8 are alkyl groups, R7 and R8 may be bonded to each other to form a ring together with the carbon atoms to which R7 and R8 are bonded.

[0072] In the binder according to this embodiment, the vinylidene fluoride polymer may be a vinylidene fluoride polymer containing a structural unit derived from a compound represented by the following formula (3). [ka] In formula (3), R4 is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a carboxyl group substituted with an alkyl group having 1 to 5 carbon atoms; R5 and R6 are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; and X is a single bond or an atomic group having a main chain consisting of 1 to 20 atoms and a molecular weight of 500 or less.

[0073] In addition, in the electrode mixture according to this embodiment, it is preferable that the active material is a lithium metal oxide represented by the following formula (4), and that when the lithium metal oxide is extracted with water, the pH of the water is 10.5 or higher. LiNi x Co y M z O2···(4) (In formula (4), M is Mn or Al, and 0 <x≦1、0<y≦1、0<z≦1である)

[0074] In the electrode mixture according to this embodiment, the content of the oxime is preferably 0.01 to 10 mmol per 100 g of the active material.

[0075] The electrode according to this embodiment includes an electrode mixture layer formed from the electrode mixture on a current collector.

[0076] The nonaqueous electrolyte secondary battery according to this embodiment includes the electrode.

[0077] The following examples are provided to further explain the embodiments of the present invention. It goes without saying that the present invention is not limited to the following examples, and various modifications are possible in detail. Furthermore, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed herein are also included in the technical scope of the present invention. Furthermore, all of the documents cited in this specification are incorporated by reference. [Example]

[0078] [Preparation Example 1] Preparation of VDF / APS copolymer A 2-L autoclave was charged with 1096 g of ion-exchanged water, 0.2 g of Metrose 90SH-100 (Shin-Etsu Chemical Co., Ltd.), 2.2 g of a 50 wt% diisopropyl peroxydicarbonate-Flon 225cb solution, 426 g of vinylidene fluoride, and an initial amount of 0.2 g of acryloyloxypropyl succinic acid (APS). The temperature was raised to 26°C over 1 hour, and then a 6 wt% aqueous APS solution was added slowly at a rate of 0.5 g / min while maintaining the temperature at 26°C. The resulting polymer slurry was dehydrated and dried to obtain a vinylidene fluoride copolymer containing polar groups (VDF / APS copolymer). A total of 4.0 g of APS was added, including the initial amount.

[0079] [Preparation Example 2] Preparation of VDF / HFP / APS copolymer A 2-L autoclave was charged with 1048 g of ion-exchanged water, 0.62 g of Metrolose SM-100 (Shin-Etsu Chemical Co., Ltd.), 3.95 g of a 50 wt% diisopropyl peroxydicarbonate-Flon 225cb solution, 374 g of vinylidene fluoride, 40 g of hexafluoropropylene (HFP), and an initial amount of 0.37 g of APS, and heated to 29 °C. A 2 wt% aqueous APS solution was continuously fed into the reactor while maintaining a constant pressure during polymerization. The resulting polymer slurry was dehydrated and dried to obtain a vinylidene fluoride copolymer (VDF / HFP / APS copolymer). A total of 3.66 g of APS was added, including the initial amount.

[0080] [Preparation Example 3] Preparation of VDF / AA copolymer A 2-liter autoclave was charged with 900 g of ion-exchanged water, 0.4 g of Metrose 90SH-100 (Shin-Etsu Chemical Co., Ltd.), 4 g of a 50 wt% perbutyl perpivalate-Flon 225cb solution, 396 g of vinylidene fluoride, and an initial amount of 0.2 g of acrylic acid (AA) and heated to 50°C. A 3 wt% aqueous AA solution was continuously fed into the reactor while maintaining a constant pressure during polymerization. The resulting polymer slurry was dehydrated and dried to obtain vinylidene fluoride copolymer (VDF / AA). A total of 1.96 g of AA was added, including the initial amount.

[0081] [Preparation Example 4] Preparation of VDF / MMM copolymer A 2-liter autoclave was charged with 1,040 g of ion-exchanged water, 0.8 g of Metrose 90SH-100 (Shin-Etsu Chemical Co., Ltd.), 2 g of diisopropyl peroxydicarbonate, 396 g of vinylidene fluoride, and 4 g of monomethyl maleate, and suspension polymerization was carried out at 28° C. The resulting polymer slurry was dehydrated and dried to obtain a vinylidene fluoride copolymer (VDF / MMM).

[0082] [Preparation Example 5] Synthesis of poly(methylvinyloxime) A 200 mL three-neck flask was purged with nitrogen and charged with 10 g (143 mmol) of methyl vinyl ketone, 1 g (6 mmol) of 2,2'-azobis(isobutyronitrile), and 40 mL of toluene (prepared with nitrogen for 20 minutes) and stirred at 70 °C for 3.5 hours. The stirred reaction solution was added to a large amount of hexane, and the precipitated crude product containing poly(methyl vinyl ketone) was recovered. The entire crude product, 12.8 g (78 mmol) of hydroxylamine sulfate, and 60 mL of pyridine were then added to a 200 mL three-neck flask and stirred at 80 °C for 4 hours. The stirred reaction solution was added to a large amount of purified water, and the precipitate was filtered off to obtain 6.8 g of the desired oxime polymer, poly(methyl vinyl oxime), in a 56% yield.

[0083] [Example 1] Preparation of electrode mixture NCA811 was used as the electrode active material. Carbon black (SP: SuperP (registered trademark) manufactured by Timcal Japan, average particle diameter: 40 nm, specific surface area: 60 m) was added to NCA811 as a conductive additive. 2 / g) was added and powder mixing was carried out.

[0084] The VDF / APS copolymer obtained in Preparation Example 1 and acetoxime were dissolved in N-methyl-2-pyrrolidone (hereinafter referred to as "NMP") to prepare a binder solution. The binder solution contained 6 wt% vinylidene fluoride polymer and 0.34 mmol of acetoxime per 1 g of vinylidene fluoride polymer. The amount of hydroxyimino groups in the acetoxime per 1 g of vinylidene fluoride polymer was 0.34 mmol.

[0085] The binder solution was added to the mixture of NCA811 and carbon black in two portions and kneaded. Specifically, the binder solution was added so that the solids concentration was 81.5 wt%, and the first kneading was performed at 2000 rpm for 2.5 minutes. Next, the remaining binder solution was added to make the solids concentration 75 wt%, and the second kneading was performed at 2000 rpm for 3 minutes to obtain an electrode mixture. The weight ratio of the electrode active material, carbon black, and VDF / APS copolymer (electrode active material:carbon black:VDF / APS copolymer) in the obtained electrode mixture was 100:2:2.

[0086] [Example 2] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 1, except that the amount of acetoxime in the binder solution was 0.17 mmol per 1 g of vinylidene fluoride polymer. At this time, the amount of hydroxyimino groups possessed by acetoxime per 1 g of vinylidene fluoride polymer was 0.17 mmol.

[0087] [Example 3] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 1, except that the amount of acetoxime in the binder solution was 0.84 mmol per 1 g of vinylidene fluoride polymer. At this time, the amount of hydroxyimino groups possessed by acetoxime per 1 g of vinylidene fluoride polymer was 0.84 mmol.

[0088] [Example 4] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 1, except that the amount of acetoxime in the binder solution was 0.09 mmol per 1 g of vinylidene fluoride polymer. At this time, the amount of hydroxyimino groups possessed by acetoxime per 1 g of vinylidene fluoride polymer was 0.09 mmol.

[0089] [Example 5] Preparation of electrode mixture Except for changing acetoxime to 2-butanone oxime, an electrode mixture was prepared in the same manner as in Example 1. At this time, the amount of hydroxyimino groups possessed by 2-butanone oxime per 1 g of vinylidene fluoride polymer was 0.34 mmol.

[0090] [Example 6] Preparation of electrode mixture Except for changing acetoxime to cyclohexanone oxime, an electrode mixture was prepared in the same manner as in Example 1. At this time, the amount of hydroxyimino groups possessed by cyclohexanone oxime per 1 g of vinylidene fluoride polymer was 0.34 mmol.

[0091] [Example 7] Preparation of electrode mixture Except for changing acetoxime to acetaldehyde oxime, an electrode mixture was prepared in the same manner as in Example 1. At this time, the amount of hydroxyimino groups possessed by acetaldehyde oxime per 1 g of vinylidene fluoride polymer was 0.34 mmol.

[0092] [Example 8] Preparation of electrode mixture Except for changing acetoxime to benzaldehyde oxime, an electrode mixture was prepared in the same manner as in Example 1. At this time, the amount of hydroxyimino groups possessed by benzaldehyde oxime per 1 g of vinylidene fluoride polymer was 0.34 mmol.

[0093] [Example 9] Preparation of electrode mixture Except for changing acetoxime to 2,3-butanedione monoxime, an electrode mixture was prepared in the same manner as in Example 1. At this time, the amount of hydroxyimino groups possessed by 2,3-butanedione monoxime per 1 g of vinylidene fluoride polymer was 0.34 mmol.

[0094] [Example 10] Preparation of electrode mixture Except for changing acetoxime to dimethylglyoxime, an electrode mixture was prepared in the same manner as in Example 1. At this time, the amount of hydroxyimino groups possessed by dimethylglyoxime per 1 g of vinylidene fluoride polymer was 0.67 mol.

[0095] [Example 11] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 1, except that the VDF / APS copolymer obtained in Preparation Example 1 was replaced with a homopolymer, KF#7300 (manufactured by Kureha Corporation).

[0096] [Example 12] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 3, except that the VDF / APS copolymer obtained in Preparation Example 1 was replaced with the VDF / HFP / APS copolymer obtained in Preparation Example 2.

[0097] [Example 13] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 1, except that the VDF / APS copolymer obtained in Preparation Example 1 was replaced with the VDF / MMM copolymer obtained in Preparation Example 4.

[0098] [Example 14] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 1, except that the VDF / APS copolymer obtained in Preparation Example 1 was replaced with the VDF / AA copolymer obtained in Preparation Example 3.

[0099] [Example 15] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 11, except that acetoxime was changed to poly(methylvinyloxime) and the amount of poly(methylvinyloxime) contained in the binder solution was adjusted so that the amount of hydroxyimino groups in the poly(methylvinyloxime) was 0.34 mmol per 1 g of vinylidene fluoride polymer.

[0100] [Comparative Example 1] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 1, except that acetoxime was not added to the binder solution.

[0101] [Comparative Example 2] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 11, except that acetoxime was not added to the binder solution.

[0102] [Comparative Example 3] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 1, except that acetoxime was changed to hydroquinone.

[0103] [Comparative Example 4] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 1, except that acetoxime was changed to 3,5-dimethylpyrazole.

[0104] [Comparative Example 5] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 1, except that acetoxime was replaced with an isocyanate compound MOI-BP (manufactured by Showa Denko K.K.). MOI-BP is 2-[0-(1'-methylpropylideneamino)carboxyamino]ethyl methacrylate.

[0105] [Comparative Example 6] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 12, except that acetoxime was not added to the binder solution.

[0106] [Comparative Example 7] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 13, except that acetoxime was not added to the binder solution.

[0107] [Comparative Example 8] Preparation of electrode mixture An electrode mixture was prepared in the same manner as in Example 14, except that acetoxime was not added to the binder solution.

[0108] [Evaluation Example 1] pH measurement of electrode active material The pH of the electrode active material (NCA811) was determined as the pH of water when the electrode active material was extracted with water at room temperature (25°C). Extraction of the electrode active material into water was performed using the extraction method specified in JIS K 5101-16-2. Specifically, the electrode active material was placed in ultrapure water in an amount 50 times the weight of the electrode active material, stirred with a magnetic stirrer at 600 rpm for 10 minutes, and the pH of the solution was measured using a pH meter model F-21 manufactured by Horiba, Ltd. The pH after extraction of NCA811 with water was 11.5.

[0109] [Evaluation Example 2] Inherent viscosity (η i ) measurement A polymer solution was prepared by dissolving 80 mg of vinylidene fluoride polymer in 20 mL of N,N-dimethylformamide. The viscosity η of the prepared polymer solution was measured using an Ubbelohde viscometer in a thermostatic bath at 30°C. The inherent viscosity (η) was calculated from the following equation: i ) was calculated. η i =(1 / C)·ln(η / η0) In the above formula, η0 is the viscosity of the solvent N,N-dimethylformamide, and C is the concentration of vinylidene fluoride polymer in the prepared polymer solution (0.4 g / dL).

[0110] [Evaluation Example 3] Measurement of the amount of constituent units of vinylidene fluoride and comonomer Polymer powder 1 The 1 H NMR spectrum was measured under the following conditions: AVANCE AC 400FT NMR spectrometer (manufactured by Bruker) was used as the instrument. <Measurement conditions> Frequency: 400MHz Measurement solvent: DMSO-d6 Measurement temperature: 25℃

[0111] The amount of structural units derived from vinylidene fluoride in the polymer and the amount of structural units derived from the comonomer, 1 The H NMR spectrum was calculated based on the integrated intensity of the signals mainly attributable to the comonomer and the signals mainly attributable to vinylidene fluoride observed at 2.24 ppm and 2.87 ppm.

[0112] When a comonomer having a structure derived from acrylic acid was used as the comonomer, the amount of structural units containing the structure derived from acrylic acid in the polymer was determined by neutralization titration using 0.03 mol / L aqueous sodium hydroxide solution. More specifically, 0.3 g of the polymer was dissolved in 9.7 g of acetone at approximately 80°C, and then 3 g of pure water was added to prepare a titration solution. Using phenolphthalein as an indicator, neutralization titration was performed at room temperature using 0.03 mol / L aqueous sodium hydroxide solution.

[0113] [Evaluation Example 4] Measurement of electrode mixture slurry viscosity The electrode mixtures obtained in the examples and comparative examples were stored at 40°C under a nitrogen atmosphere for a predetermined time (24 hours or 168 hours). Then, the electrode mixtures were measured using an E-type viscometer at 25°C and a shear rate of 2 s -1 The measurement was carried out at 100°C. The viscosity was measured by waiting 60 seconds after loading the slurry (electrode mixture) into the measuring device and then rotating the rotor. The value 300 seconds after the start of rotor rotation was taken as the slurry viscosity. The slurry viscosity of the electrode mixture immediately after preparation was taken as the initial slurry viscosity.

[0114] Table 1 shows the materials used in preparing the electrode mixtures of the examples and comparative examples. In Table 1, "VDF / comonomer" indicates the weight ratio of VDF to the weight ratio of comonomer in the vinylidene fluoride polymer. Example 12 and Comparative Example 6 indicate the weight ratio of VDF to the weight ratio of HFP (comonomer) to the weight ratio of APS (comonomer) in the vinylidene fluoride polymer. MMM indicates monomethyl maleate. The isocyanate compound in Comparative Example 5 is 2-[0-(1'-methylpropylideneamino)carboxyamino]ethyl methacrylate. The amount of hydroxyimino groups is the amount of hydroxyimino groups in the oxime per 1 g of vinylidene fluoride polymer in the binder (mmol / g vinylidene fluoride polymer).

[0115] [Table 1]

[0116] The evaluation results of the electrode mixtures of Examples and Comparative Examples are shown in Table 2. For the electrode mixtures of Examples 12 to 14 and Comparative Examples 1 to 8, the slurry viscosity was not measured after storage for 168 hours.

[0117] [Table 2]

[0118] As can be seen from Tables 1 and 2, the electrode mixtures of Examples 1 to 15, which used a binder containing an oxime, had a slurry viscosity lower than the initial slurry viscosity after 24 hours of storage. On the other hand, the electrode mixtures of Comparative Examples 1 to 8, which used a binder not containing an oxime, had a slurry viscosity higher than the initial slurry viscosity after 24 hours of storage. This indicates that the electrode mixtures of Examples 1 to 15 have high gelation resistance. In particular, the electrode mixtures of Examples 1, 3, 5, 6, 10, and 11 had a slurry viscosity lower than the initial slurry viscosity after 168 hours of storage, indicating that they have excellent gelation resistance. [Industrial Applicability]

[0119] The present invention can be used in lithium ion secondary batteries.

Claims

1. an electrode mixture containing a vinylidene fluoride polymer containing 50 mol % or more of vinylidene fluoride units, an oxime, and an active material is applied onto a current collector; The electrode mixture is dried to obtain an electrode mixture layer. Electrode manufacturing method.

2. 2. The method for producing an electrode according to claim 1, wherein the oxime is at least one oxime selected from a compound represented by the following formula (1), a compound represented by the following formula (2), and a polymer or oligomer having a hydroxyimino group: 【Chemistry 1】 【Chemistry 2】 In formula (1), R １ and R ２ are each independently selected from a hydrogen atom, an aldehyde group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, an aryl group having 6 to 18 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, and a heterocyclic group having 3 to 13 carbon atoms, and some or all of the hydrogen atoms of these groups may be substituted with a substituent selected from an alkyl group having 1 to 10 carbon atoms, an aryl group, a hydroxyl group, and an amino group; R １ and R ２ are bonded to each other to form R １ and R ２ may form a ring together with the carbon atom to which it is attached, In formula (2), R ７ and R ８ are each independently selected from a hydrogen atom, an aldehyde group, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a cycloalkenyl group having 3 to 10 carbon atoms, an aryl group having 6 to 18 carbon atoms, an aralkyl group having 7 to 14 carbon atoms, and a heterocyclic group having 3 to 13 carbon atoms, and some or all of the hydrogen atoms of these groups may be substituted with a substituent selected from an alkyl group having 1 to 10 carbon atoms, an aryl group, a hydroxyl group, and an amino group; R 7 and R ８ are bonded to each other to form R ７ and the carbon atom to which R ８ may form a ring together with the carbon atom to which it is attached.

3. In the formula (1), R １ and R ２ are each independently selected from a hydrogen atom, an aryl group having 6 to 18 carbon atoms, an aldehyde group, or an alkyl group having 1 to 10 carbon atoms, and some or all of the hydrogen atoms of these groups may be substituted with a substituent selected from an alkyl group having 1 to 10 carbon atoms, an aryl group, a hydroxyl group, and an amino group; R １ and R ２ is an alkyl group, R １ and R ２ are bonded to each other to form R １ and R ２ may form a ring together with the carbon atom to which it is attached, In the formula (2), R ７ and R ８ are each independently selected from a hydrogen atom, an aryl group having 6 to 18 carbon atoms, an aldehyde group, or an alkyl group having 1 to 10 carbon atoms, and some or all of the hydrogen atoms of these groups may be substituted with a substituent selected from an alkyl group having 1 to 10 carbon atoms, an aryl group, a hydroxyl group, and an amino group; R ７ and R ８ is an alkyl group, R ７ and R ８ are bonded to each other to form R ７ and the carbon atom to which R ８ may form a ring together with the carbon atom to which it is attached, The method for manufacturing the electrode according to claim 2 .

4. In the formula (1), R １ and R ２ are each independently selected from alkyl groups having 1 to 10 carbon atoms; R １ and R ２ is an alkyl group, R １ and R ２ are bonded to each other to form R １ and R ２ may form a ring together with the carbon atom to which it is attached, In the formula (2), R ７ and R ８ are each independently selected from a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, R ７ and R ８ is an alkyl group, R ７ and R ８ are bonded to each other to form R ７ and the carbon atom to which R ８ may form a ring together with the carbon atom to which it is attached, The method for manufacturing the electrode according to claim 2 .

5. The method for producing an electrode according to any one of claims 1 to 4, wherein the vinylidene fluoride polymer is a vinylidene fluoride polymer containing a structural unit derived from a compound represented by the following formula (3): 【Transformation 3】 In formula (3), R ４ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a carboxyl group substituted with an alkyl group having 1 to 5 carbon atoms, R ５ and R ６ are each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, X is a single bond or an atomic group having a main chain composed of 1 to 20 atoms and a molecular weight of 500 or less.

6. The method for producing an electrode according to any one of claims 1 to 5, wherein the active material is a lithium metal oxide represented by the following formula (4), and when the lithium metal oxide is extracted with water, the pH of the water is 10.5 or higher: L)) ｘ Co ｙ M ｚ O ２ ・・・(4) (In formula (4), M is Mn or Al, and 0<x≦1, 0<y≦1, and 0<z≦1.)

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