Electrode slurry additive and solid battery

Abstract

The present invention relates to an electrode paste additive and a solid-state battery comprising the same, the electrode paste additive being an acrylic resin containing a structural unit having a linear alkyl group having 14 or more carbon atoms and a structural unit having a basic functional group, the electrode paste additive having a weight-average molecular weight of more than 50,000 and less than 200,000 and an amine value of 5 mgKOH / g to 33 mgKOH / g, and a solid-state battery comprising the electrode paste additive.

Description

Technical Field

[0001] The present disclosure relates to electrode slurry additives and solid batteries. Background Art

[0002] When manufacturing an electrode having an electrode layer containing an active material, a slurry containing the active material, etc. (hereinafter also referred to as "electrode slurry") is sometimes applied and dried to manufacture an electrode having an electrode layer. In the electrode slurry, additives (electrode slurry additives) are sometimes used to improve the dispersion stability of components in the slurry such as the active material.

[0003] Japanese Patent Application Publication No. 2011-014387 proposes an all-solid secondary battery having a positive electrode, a solid electrolyte layer, and a negative electrode, wherein at least one of the positive electrode, the solid electrolyte layer, and the negative electrode contains a graft polymer.

[0004] In International Publication No. 2022 / 085637, a composition containing an inorganic solid electrolyte is proposed, which is a composition containing an inorganic solid electrolyte having ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, a polymer binder, and a dispersion medium, wherein the polymer binder comprises a constituent component (X) containing a polymer chain, and a constituent component (A) having at least one functional group among the following functional group groups (a), and a polymer having a constituent component (N) containing a nitrogen atom at a content of less than 10 mol % in all the constituent components, and is dissolved in the above-mentioned dispersion medium. Summary of the invention

[0005] The graft polymer as the electrode slurry additive described in the Japanese Patent Publication No. 2011-014387 does not have an adsorption group (e.g., a basic functional group) for the active material, etc., and therefore has a tendency of poor dispersibility of the active material. In addition, the polymer binder as the electrode slurry additive described in the International Publication No. 2022 / 085637 has an acidic functional group, so when the electrode slurry contains a solid electrolyte, it sometimes has a tendency to easily cause the degradation of the solid electrolyte, lacking versatility.

[0006] In the present disclosure, an additive added to the electrode slurry in order to improve the dispersion stability of components (active material, etc.) used for preparing the electrode slurry is also referred to as an "electrode slurry additive."

[0007] An object of one embodiment of the present disclosure is to provide an electrode slurry additive that improves the dispersion stability of components in the slurry.

[0008] Another embodiment of the present disclosure aims to provide a solid battery including an electrode slurry additive that improves the dispersion stability of components in the slurry.

[0009] Means for solving the above-mentioned problems include the following means.

[0010] <1> An electrode slurry additive, which is an acrylic resin comprising a structural unit having a linear alkyl group having 14 or more carbon atoms and a structural unit having a basic functional group,

[0011] The weight average molecular weight is more than 50,000 and less than 200,000,

[0012] The amine value is 5 mgKOH / g or more and 33 mgKOH / g or less.

[0013] <2> The electrode slurry additive according to <1>, wherein the content ratio of the structural unit having a linear alkyl group having 14 or more carbon atoms is 30% by mass or more and 65% by mass or less based on the total structural units contained in the acrylic resin.

[0014] <3> The electrode slurry additive according to <1> or <2>, wherein the content ratio of the structural unit having a basic functional group is 0.5 mass % or more and 10 mass % or less based on the total amount of the structural units contained in the acrylic resin.

[0015] <4> The electrode slurry additive according to any one of <1> to <3>, which is a random polymer.

[0016] <5> An electrode slurry comprising the electrode slurry additive according to any one of <1> to <4>, an active material, a conductive additive, a solid electrolyte, and a solvent.

[0017] <6> The electrode slurry according to <5>, wherein the solvent is a solvent selected from the group consisting of butyl butyrate, dibutyl ether, anisole, mesitylene, diisobutyl ketone, methyl isobutyl ketone, cyclopentyl methyl ether, toluene, and heptane.

[0018] <7> An electrode comprising the electrode slurry additive according to any one of <1> to <4>.

[0019] <8> A solid battery comprising the electrode slurry additive according to any one of <1> to <4>.

[0020] According to one embodiment of the present disclosure, an electrode slurry additive is provided that improves the dispersion stability of components in the slurry.

[0021] According to another embodiment of the present disclosure, a solid battery including an electrode slurry additive that improves the dispersion stability of components in the slurry is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic cross-sectional view showing one embodiment of the battery disclosed herein. DETAILED DESCRIPTION

[0023] Hereinafter, an embodiment as an example of the present disclosure will be described. These descriptions and examples are exemplary embodiments and do not limit the scope of the invention.

[0024] The term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the intended effect of the process is achieved.

[0025] The “acrylic resin” in the present disclosure includes both a resin having an acrylic monomer unit containing an acryloyl group and a resin having a methacrylic monomer unit containing a methacryloyl group.

[0026] <Electrode slurry additives>

[0027] The electrode slurry additive disclosed herein is an acrylic resin containing a structural unit having a linear alkyl group with 14 or more carbon atoms and a structural unit having a basic functional group, having a weight average molecular weight of more than 50,000 and less than 200,000, and an amine value of more than 5 mgKOH / g and less than 33 mgKOH / g.

[0028] The electrode slurry additive according to the present disclosure can improve the dispersion stability of the components in the slurry by the above-mentioned configuration. The reason for this is presumably as follows.

[0029] By including a structural unit having a basic functional group, the amine value is made 5 mgKOH / g or more and 33 mgKOH / g or less, so that the components (active materials, etc.) in the slurry are efficiently adsorbed. In addition, by making the weight average molecular weight in the range of more than 50,000 and less than 200,000, the adsorption stability is improved. Furthermore, by including a structural unit having a straight-chain alkyl group with more than 14 carbon atoms, the dispersion stability of the components in the slurry is improved.

[0030] In summary, the electrode slurry additive disclosed herein can improve the dispersion stability of the components in the slurry.

[0031] (structure)

[0032] The electrode slurry additive disclosed herein is an acrylic resin comprising a structural unit having a linear alkyl group with a carbon number of 14 or more and a structural unit having a basic functional group. The structural unit having a linear alkyl group with a carbon number of 14 or more is preferably a structural unit derived from a polymerizable unsaturated monomer having a linear alkyl group with a carbon number of 14 or more. In addition, the structural unit having a basic functional group is preferably a structural unit derived from a polymerizable unsaturated monomer having a basic functional group.

[0033] The electrode slurry additive according to the present disclosure, which is an acrylic resin, is preferably a copolymer, and may be either a random copolymer or a block copolymer, and is preferably a random copolymer.

[0034] Among acrylic resins, poly(meth)acrylate is preferred from the viewpoint of dispersibility of the electrode slurry.

[0035] -Structural unit having a linear alkyl group having 14 or more carbon atoms-

[0036] The electrode slurry additive disclosed herein has a structural unit containing a linear alkyl group having 14 or more carbon atoms. From the viewpoint of the dispersibility of the conductive aid, the number of carbon atoms of the linear alkyl group is preferably 16 or more carbon atoms, more preferably 18 or more carbon atoms. More preferably, it is 16 or more and 24 or less, more preferably 18 or more and 22 or less. The structural unit having a linear alkyl group having 14 or more carbon atoms can be used alone or in combination of two or more.

[0037] Specific examples of the linear alkyl group having 14 or more carbon atoms include tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl (stearyl), nonadecyl, eicosyl, and behenyl groups, with octadecyl (stearyl) and behenyl groups being more preferred.

[0038] Examples of the structural unit having a linear alkyl group having 14 or more carbon atoms include a structural unit represented by the following formula (1).

[0039]

[0040] In the above formula (1), R 1 is a hydrogen atom or a methyl group, R 2 It is a straight-chain alkyl group having 14 or more carbon atoms.

[0041] R 1 Preferred is methyl.

[0042] As R 2 Specific examples of the linear alkyl group having 14 or more carbon atoms are as described above, and the preferred embodiments are also the same.

[0043] As the content ratio of the structural unit having a straight-chain alkyl group with a carbon number of 14 or more, from the viewpoint of the dispersibility of the components in the slurry, it is preferably 30% by mass or more and 65% by mass or less, more preferably 35% by mass or more and 60% by mass or less, and further preferably 40% by mass or more and 55% by mass or less relative to the overall structural unit contained in the acrylic resin. If the content ratio of the structural unit having a straight-chain alkyl group with a carbon number of 14 or more is 30% by mass or more, the dispersibility of the conductive aid becomes better. If the content ratio of the structural unit having a straight-chain alkyl group with a carbon number of 14 or more is 65% by mass or less, the dispersibility of the active material and the solid electrolyte is more excellent.

[0044] Examples of the structural unit having a linear alkyl group having 14 or more carbon atoms include structural units derived from a polymerizable unsaturated monomer having a linear alkyl group having 14 or more carbon atoms.

[0045] Specific examples of the polymerizable unsaturated monomer having a linear alkyl group having 14 or more carbon atoms include tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, heneicosyl (meth)acrylate, behenyl (meth)acrylate, tricosyl (meth)acrylate, and tetracosyl (meth)acrylate. These may be used alone or in combination of two or more.

[0046] -Structural unit having a basic functional group-

[0047] The electrode slurry additive disclosed herein comprises a structural unit having a basic functional group.

[0048] The basic functional group refers to a functional group that exhibits Bronsted basicity in an aqueous solution.

[0049] As the basic functional group, for example, primary amino group, secondary amino group, tertiary amino group, quaternary ammonium salt group, imino group, hydrazine group, pyridyl group, pyrimidyl group, pyrazinyl group, imidazole group, triazole group, amide group, etc. can be mentioned. These basic functional groups can have only one kind or two or more kinds. Among them, from the viewpoint of dispersibility of the electrode slurry, the basic functional group is preferably at least one basic functional group selected from the group consisting of secondary amino group, tertiary amino group, imino group and amide group.

[0050] Examples of the structural unit having a basic functional group include a structural unit represented by the following formula (2).

[0051]

[0052] In the above formula (2), R 1 R in the above formula (1) 1 Same meaning, R 3 and R 4 Each independently represents a hydrogen atom or an alkyl group having 1 or more carbon atoms.

[0053] R 1 Preferred is methyl.

[0054] R 3 and R 4 An alkyl group having 1 to 6 carbon atoms is preferred, an alkyl group having 1 to 3 carbon atoms is more preferred, and a methyl group is further preferred.

[0055] As the content ratio of the structural unit having a basic functional group, from the viewpoint of adsorption of the components in the slurry, it is preferably 0.5% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 8% by mass or less, and further preferably 1.5% by mass or more and 6% by mass or less relative to the overall structural unit contained in the acrylic resin. If the content ratio of the structural unit having a basic functional group is 0.5% by mass or more, the dispersibility of the conductive aid and the active material becomes better. If the content ratio of the structural unit having a basic functional group is 10% by mass or less, the dispersibility of the solid electrolyte is excellent.

[0056] Examples of the structural unit having a basic functional group include structural units derived from a polymerizable unsaturated monomer having a basic functional group. The polymerizable unsaturated monomer having a basic functional group can be used without particular limitation as long as it has a basic functional group.

[0057] Specific examples of the polymerizable unsaturated monomer having a basic functional group include (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-butyl(meth)acrylamide, N-tert-butyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dimethylaminoethyl(meth)acrylate, N,N-diethylaminoethyl(meth)acrylate, N,N-dimethylaminopropyl(meth)acrylamide, and adducts of glycidyl(meth)acrylate and amines. These may be used alone or in combination of two or more.

[0058] -Other structural units-

[0059] The electrode slurry additive according to the present disclosure may include other structural units in addition to the structural unit having a linear alkyl group having 14 or more carbon atoms and the structural unit having a basic functional group.

[0060] Specific examples of the other structural units include structural units derived from the following polymerizable unsaturated monomers.

[0061] Examples of the polymerizable unsaturated monomer include (meth)acrylate esters containing a linear, branched or cyclic alkyl group, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, lauryl (meth)acrylate, isostearyl acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and tridecyl (meth)acrylate; polymerizable unsaturated monomers containing a monocyclic aromatic hydrocarbon, such as styrene, phenyl (meth)acrylate, phenylalkyl (meth)acrylate, and vinyltoluene; and vinylnaphthalene, naphthyl (meth)acrylate, naphthylalkyl (meth)acrylate, vinylanthracene, anthracenyl (meth)acrylate, anthracenylalkyl (meth)acrylate, vinylpyrene, pyrenyl (meth)acrylate, pyrenylalkyl (meth)acrylate, and vinyl Polymerizable unsaturated monomers having polycyclic aromatic hydrocarbons such as vinyl tetracene, vinyl pentacene, and derivatives thereof; monoesters of (meth)acrylic acid and a divalent alcohol having 2 to 8 carbon atoms such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate, ε-caprolactone-modified monoesters of (meth)acrylic acid and a divalent alcohol having 2 to 8 carbon atoms, N-hydroxymethyl (meth)acrylamide, N,N-bis(2-hydroxymethyl)acrylamide, N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]acrylamide, N-hydroxyethyl (meth)acrylamide, N,N-bis(2-hydroxyethyl) (meth)acrylamide, N-hydroxypropyl (meth)acrylamide, N,N-bis(2-hydroxypropyl)acrylamide, N-(1,1-dimethyl-3-hydroxybutyl)acrylamide, allyl alcohol, (meth)acrylates having a polyoxyalkylene chain with a hydroxyl group at the molecular end; (meth)acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate and other polymerizable unsaturated monomers containing a carboxyl group; polymerizable unsaturated monomers having a urethane bond such as a reaction product of a polymerizable unsaturated monomer containing an isocyanate group and a hydroxyl group-containing compound or a reaction product of a polymerizable unsaturated monomer containing a hydroxyl group and an isocyanate group-containing compound; glycidyl (meth)acrylate, β- Epoxy group-containing polymerizable unsaturated monomers such as methyl glycidyl (meth)acrylate, 3,4-epoxycyclohexyl methyl (meth)acrylate, 3,4-epoxycyclohexyl ethyl (meth)acrylate, 3,4-epoxycyclohexyl propyl (meth)acrylate, and allyl glycidyl ether; (meth)acrylates having a polyoxyethylene chain with an alkoxy group at the molecular end; polymerizable unsaturated monomers having a sulfonic acid group such as 2-acrylamide-2-methylpropane sulfonic acid, 2-sulfoethyl (meth)acrylate, allyl sulfonic acid, 4-styrene sulfonic acid, and the sodium salts and ammonium salts of these sulfonic acids; 2-(meth)acryloyloxyethyl acid phosphate, 2-(meth)acryloyloxypropyl acid phosphate, and the like; polymerizable unsaturated monomers; polymerizable unsaturated monomers having alkoxysilyl groups, such as vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tri(2-methoxyethoxy)silane, γ-(meth)acryloxypropyl trimethoxysilane, γ-(meth)acryloxypropyl triethoxysilane; perfluoroalkyl (meth)acrylates, such as perfluorobutyl ethyl (meth)acrylate and perfluorooctyl ethyl (meth)acrylate; polymerizable unsaturated monomers having fluoroalkyl groups, such as fluoroolefins; polymerizable unsaturated monomers having photopolymerizable functional groups, such as maleimide groups; alkoxy (meth)acrylates, such as methoxy (meth)acrylate, ethoxy (meth)acrylate and butoxy (meth)acrylate;Allyl (meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tetra(meth)acrylate, glycerol di(meth)acrylate, 1,1,1-trihydroxymethylethane di(meth)acrylate, 1,1,1-trihydroxymethylethane tri(meth)acrylate, 1,1,1-trihydroxymethylpropane tri(meth)acrylate, triallyl isocyanurate, diallyl terephthalate, divinylbenzene and other polymerizable unsaturated monomers having two or more unsaturated groups; etc.;

[0062] Among the polymerizable unsaturated monomers, from the viewpoint of dispersibility of the conductive aid, it is particularly preferable to use a polymerizable unsaturated monomer having an alkyl group having 4 or more and less than 8 carbon atoms.

[0063] - Specific structure of electrode slurry additives -

[0064] The electrode slurry additive according to the present disclosure may be a random polymer or a block polymer, but is preferably a random polymer from the viewpoint of dispersion stability.

[0065] Furthermore, from the viewpoint of dispersion stability, the electrode slurry additive according to the present disclosure is preferably a poly(meth)acrylate.

[0066] Specific examples of acrylic resins as electrode slurry additives of the present disclosure are shown below. However, the electrode slurry additives of the present disclosure are not limited to these. In addition, the acrylic resins in Table 1 are all random polymers. In addition, the numerical value of "mass %" of each structural unit in Table 1 refers to the ratio of the mass of each structural unit to the total structural unit contained in the acrylic resin.

[0067] Table 1

[0068]

[0069] (Weight average molecular weight)

[0070] The weight average molecular weight of the electrode slurry additive of the present disclosure is more than 50,000 and less than 200,000, and is preferably 60,000 to 180,000, more preferably 70,000 to 170,000, further preferably 80,000 to 160,000, and also preferably 100,000 to 160,000 from the viewpoint of dispersion stability.

[0071] - Determination of weight average molecular weight -

[0072] The weight average molecular weight of the electrode slurry additive involved in the present disclosure is a value obtained by converting the retention time (retention capacity) measured using gel permeation chromatography (GPC) to the molecular weight of polystyrene by the retention time (retention capacity) of a standard polystyrene with a known molecular weight measured under the same conditions. For example, "HLC8120GPC" (trade name, manufactured by Tosoh Corporation) can be used as GPC, and "TSKgel G-4000HXL", "TSKgel G-3000HXL", "TSKgel G-2500HXL" and "TSKgel G-2000HXL" (trade name, all manufactured by Tosoh Corporation) are used as columns, and the mobile phase is tetrahydrofuran, the measurement temperature is 40°C, the flow rate is 1mL / min and the detector RI is measured.

[0073] (Amine value)

[0074] The amine value of the electrode slurry additive disclosed herein is 5 mgKOH / g to 33 mgKOH / g, and is preferably 6 mgKOH / g to 30 mgKOH / g, more preferably 6 mgKOH / g to 25 mgKOH / g, and also preferably 6 mgKOH / g to 15 mgKOH / g, from the viewpoint of dispersibility and conductivity of the electrode slurry.

[0075] ~Determination of amine value~

[0076] The amine value of the electrode slurry additive was measured in accordance with JIS K 7237 (1995).

[0077] (Synthesis method of electrode slurry additive)

[0078] The electrode slurry additives disclosed herein can be synthesized by copolymerizing a polymerizable unsaturated monomer having a straight-chain alkyl group with more than 14 carbon atoms, a polymerizable unsaturated monomer having a basic functional group, and other polymerizable unsaturated monomers as required. The synthesis can use a conventionally known method. For example, it can be manufactured by solution polymerization of a polymerizable unsaturated monomer in an organic solvent. However, it is not limited thereto. For example, it can be bulk polymerization, emulsion polymerization, suspension polymerization, etc. In the case of solution polymerization, it can be continuous polymerization or batch polymerization. The polymerizable unsaturated monomers can be added together, separately, or continuously or intermittently.

[0079] -Polymerizable unsaturated monomer-

[0080] The details of the polymerizable unsaturated monomer having a linear alkyl group having 14 or more carbon atoms, the polymerizable unsaturated monomer having a basic functional group, and other polymerizable unsaturated monomers used in the synthesis of the electrode slurry additive according to the present disclosure have been described above, and thus description thereof is omitted here.

[0081] -Free Radical Polymerization Initiator-

[0082] The free radical polymerization initiator used for polymerization can use a conventionally known substance. As the free radical polymerization initiator, for example, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, 1,1-bis(tert-butylperoxide)-3,3,5-trimethylcyclohexane, 1,1-bis(tert-butylperoxide)cyclohexane, n-butyl-4,4-bis(tert-butylperoxide)valerate, isopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,3-bis(tert-butylperoxide-m-isopropyl)benzene, 2,5-dimethyl-2,5-di(tert-butylperoxide)hexane, diisopropylbenzene peroxide, tert-butylcumyl peroxide, decanoyl peroxide, lauroyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, di-tert-amyl peroxide, dihydroperoxide, ...2,5-dihydroperoxide, 2,5-dihydroperoxide, 2,5-dihydroperoxide, 2,5-dihydroperoxide, 2,5-dihydroperoxide, 2,5-dihydroperoxide, 2,5-dihydroperoxide, 2,5-dihydroperoxide, 2,5-dihydroperoxide, 2,5-dihydroperoxide, 2 Peroxide polymerization initiators such as (tert-butylcyclohexyl) peroxydicarbonate, tert-butyl peroxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, and tert-butyl peroxy-2-ethylhexanoate; azo polymerization initiators such as 2,2'-azobis(isobutyronitrile), 1,1-azobis(cyclohexane-1-carbonitrile), azoisopropylbenzene, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(dimethylvaleronitrile), 4,4'-azobis(4-cyanovaleric acid), 2-(tert-butylazo)-2-cyanopropane, 2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane), and dimethyl 2,2'-azobis(2-methylpropionate). The radical polymerization initiators may be used alone or in combination of two or more.

[0083] -Solvents-

[0084] The solvent used for the polymerization and / or dilution is not particularly limited, and examples thereof include water, an organic solvent, and a mixture thereof.

[0085] Examples of the organic solvent include conventionally known solvents. Examples of the organic solvent include hydrocarbon solvents such as n-butane, n-hexane, n-heptane, n-octane, cyclopentane, cyclohexane, and cyclobutane; aromatic solvents such as toluene, xylene, mesitylene, and tetralin; n-butyl ether, dimethicone, and tetralin; Ether solvents such as oxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, and diethylene glycol; ester solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, butyl butyrate, ethylene glycol monomethyl ether acetate, and butyl carbitol acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and diisobutyl ketone; alcohol solvents such as ethanol, isopropanol, n-butanol, sec-butanol, and isobutanol; amide solvents such as Ecoamide (trade name, manufactured by Idemitsu Kosan Co., Ltd.), N,N-dimethylformamide, N,N-dimethylacetamide, N-methylformamide, N-methylacetamide, N-methylpropionamide, and N-methyl-2-pyrrolidone.

[0086] The solvent may be used alone or in combination of two or more.

[0087] The solvent used for polymerization and / or dilution is mixed in the electrode slurry additive without being removed in the desolvation step, and therefore, polymerization and / or dilution are preferably performed using a solvent used in the preparation of the electrode slurry described below.

[0088] In the case of solution polymerization in an organic solvent, the following methods are used: a method in which a free radical polymerization initiator, a polymerizable unsaturated monomer, and an organic solvent are mixed and heated while stirring; a method in which an organic solvent is added to a reaction tank in order to suppress a temperature rise of the system caused by the heat of reaction, an inert gas such as nitrogen or argon is blown into the reaction tank at a temperature of 60° C. to 200° C. while stirring, and the polymerizable unsaturated monomer and the free radical polymerization initiator are mixed and added dropwise or separately and added dropwise for a prescribed period of time; etc.

[0089] The polymerization can be generally carried out for about 1 to 10 hours. After each stage of the polymerization, a catalyst addition step of heating the reaction vessel while dropping a radical polymerization initiator may be provided as necessary.

[0090] <Battery>

[0091] The battery of the present disclosure includes the electrode slurry additive of the present disclosure as described above.

[0092] The battery involved in the present disclosure preferably has a positive electrode, a negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode, and is preferably a solid battery having a solid electrolyte layer as an electrolyte. The positive electrode preferably has a positive electrode layer and a positive electrode collector, and the negative electrode preferably has a negative electrode layer and a negative electrode collector. The laminated structure of the solid battery involved in the present disclosure can include, for example, positive electrode collector / positive electrode layer / electrolyte layer / negative electrode layer / negative electrode collector. The solid battery involved in the present disclosure can be a structure in which the electrode slurry additive involved in the present disclosure is included in at least one selected from the positive electrode layer, the electrolyte layer and the negative electrode layer.

[0093] Solid batteries include so-called all-solid batteries using solid electrolytes as electrolytes, and the solid electrolyte may contain an electrolyte solution in an amount of less than 10% by mass relative to the total amount of the electrolyte. In addition, the solid electrolyte may be a composite solid electrolyte comprising an inorganic solid electrolyte and a polymer electrolyte.

[0094] (positive electrode)

[0095] The positive electrode preferably has a positive electrode layer and a positive electrode current collector. The positive electrode layer contains a positive electrode active material and a solid electrolyte, and may contain the electrode slurry additive, conductive additive, binder, and other components according to the present disclosure as needed.

[0096] - Positive electrode layer -

[0097] The positive electrode active material preferably contains a lithium composite oxide. The lithium composite oxide may contain at least one selected from F, Cl, N, S, Br and I.

[0098] The solid electrolyte preferably contains at least one solid electrolyte type selected from the group consisting of a sulfide solid electrolyte, an oxide solid electrolyte, and a halide solid electrolyte, and more preferably contains a sulfide solid electrolyte.

[0099] As the sulfide solid electrolyte, it is preferred to contain sulfur (S) as the main component of the anion element, and it is further preferred to contain, for example, Li element, A element, and S element. The A element is at least one selected from P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In. The sulfide solid electrolyte may further contain at least one of O and a halogen element.

[0100] Examples of the conductive auxiliary agent include carbon materials, metal materials, and conductive polymer materials.

[0101] Examples of the binder include vinyl halide resins, rubbers, and polyolefin resins.

[0102] Examples of other components include oxide solid electrolytes, halide solid electrolytes, thickeners, surfactants, dispersants, wetting agents, defoaming agents, and solvents.

[0103] As a solvent, the same solvent as the organic solvent that can be used in the synthesis of the electrode slurry additive of the present disclosure can be cited. In the present disclosure, as a solvent, preferably an ester, ether, ketone, and hydrocarbon solvent, wherein, more preferably a solvent selected from butyl butyrate, dibutyl ether, anisole, mesitylene, diisobutyl ketone, methyl isobutyl ketone, cyclopentyl methyl ether, toluene, and heptane, and more preferably a solvent selected from anisole, mesitylene, diisobutyl ketone, and methyl isobutyl ketone. In the case of a slurry for modulating an electrode or an electrolyte layer, it is difficult to stably disperse the three kinds of conductive aids, electrolytes (especially solid electrolytes), and active materials at the same time. In the present disclosure, since the above-mentioned electrode slurry additive is included, the reactivity with the electrolyte (especially solid electrolyte) can be kept low, and the dispersion of the mixed system containing the three kinds of conductive aids, electrolytes (especially solid electrolytes) and active materials can be stably performed.

[0104] -Positive electrode collector-

[0105] Examples of the positive electrode current collector include stainless steel, aluminum, nickel, iron, titanium, carbon, etc., and preferably aluminum alloy foil or aluminum foil. The shape of the positive electrode current collector is, for example, foil or mesh.

[0106] (negative electrode)

[0107] The negative electrode preferably has a negative electrode layer and a negative electrode current collector. The negative electrode layer contains a negative electrode active material and a solid electrolyte, and may contain the electrode slurry additive, conductive additive, binder, and other components according to the present disclosure as needed.

[0108] - Negative electrode layer -

[0109] Examples of the negative electrode active material include Li-based active materials such as metallic lithium, carbon-based active materials such as graphite, oxide-based active materials such as lithium titanate, and Si-based active materials such as simple Si.

[0110] The solid electrolyte, conductive aid, binder and other components may be the same as those already described.

[0111] -Negative electrode collector-

[0112] The negative electrode current collector collects current from the negative electrode layer. Examples of the negative electrode current collector include stainless steel, aluminum, copper, nickel, iron, titanium, carbon, etc., preferably copper. The shape of the negative electrode current collector is, for example, foil or mesh.

[0113] (Electrolyte layer)

[0114] The electrolyte layer may be a layer containing a solid electrolyte. In the case of a layer containing a solid electrolyte (solid electrolyte layer), the solid electrolyte layer preferably contains one selected from a sulfide solid electrolyte, an oxide solid electrolyte, and a halide solid electrolyte. The solid electrolyte layer may contain the electrode slurry additive and a binder involved in the present disclosure, or may not contain a binder. As a binder that can be contained in the solid electrolyte layer, the same substance as the binder already described is applied.

[0115] Figure 1 It is a schematic cross-sectional view showing one embodiment of the battery according to the present disclosure. Figure 1 The battery 10 in the embodiment includes a positive electrode layer 1 containing a positive electrode active material, a negative electrode layer 2 containing a negative electrode active material, an electrolyte layer 3 disposed between the positive electrode layer 1 and the negative electrode layer 2, a positive electrode collector 4 for collecting current from the positive electrode layer 1, a negative electrode collector 5 for collecting current from the negative electrode layer 2, and an outer casing 6 for housing these components. The battery 10 may be configured such that the electrode slurry additive of the present disclosure is contained in at least one selected from the positive electrode layer 1, the electrolyte layer 3, and the negative electrode layer 2.

[0116] <Method for manufacturing solid state battery>

[0117] The method for producing a solid battery according to the present disclosure includes a step of preparing a positive electrode, a negative electrode, and an electrolyte layer or a separator (preparation step), and a step of sequentially stacking the positive electrode, the electrolyte layer or the separator, and the negative electrode (stacking step).

[0118] (Preparation process)

[0119] The preparation step is a step of preparing a positive electrode, a negative electrode, and an electrolyte layer or a separator.

[0120] The method for preparing the positive electrode, negative electrode and electrolyte layer is not particularly limited, but is preferably a method having the following steps: after mixing the components that may be contained in the positive electrode layer, negative electrode layer and electrolyte layer and a solvent to obtain a slurry, the obtained slurry is applied to a substrate, dried to obtain a dry film, and the obtained dry film is pressed.

[0121] As the electrode slurry used for the production of the positive electrode and the negative electrode, for example, a slurry containing the electrode slurry additive, active material, conductive aid, solid electrolyte, and solvent (and preferably a binder) involved in the present disclosure is suitable. As the above-mentioned solvent, the case of containing at least one of the solvents selected from ester, ether, ketone, and hydrocarbon is effective in the stabilization of dispersion. Further, the case of containing a solvent selected from butyl butyrate, dibutyl ether, anisole, mesitylene, diisobutyl ketone, methyl isobutyl ketone, cyclopentyl methyl ether, toluene, and heptane is more effective in the stabilization of dispersion, and the case of containing a solvent selected from anisole, mesitylene, diisobutyl ketone, and methyl isobutyl ketone is further effective in the stabilization of dispersion. That is, in the case of using the above-mentioned solvent to modulate a slurry containing an active material, a conductive aid, and a solid electrolyte, the active material, the conductive aid, and the solid electrolyte can be dispersed simultaneously and stably, and as a result, the battery performance can be improved.

[0122] Examples of a method for pressing the dry film include roll pressing and cold isostatic pressing (CIP).

[0123] (Lamination process)

[0124] The lamination step is a step of laminating the positive electrode, the electrolyte layer or the separator, and the negative electrode in this order.

[0125] In the lamination step, the positive electrode, the electrolyte layer or the separator, and the negative electrode prepared in the preparation step are preferably laminated in this order and pressed as necessary to obtain a laminated body (electrode body).

[0126] The solid battery according to the present disclosure is preferably manufactured through the above steps.

[0127] Example

[0128] Hereinafter, examples are shown for embodiments of the electrode slurry additive and the like according to the present disclosure. However, the present invention is not limited to these examples. In the following description, "parts" and "%" are all based on mass unless otherwise specified.

[0129] The synthesis process of the electrode slurry additive and the production process of the all-solid-state battery are described below. The structures of polymers 1 to 8 (electrode slurry additives according to the present disclosure) are the same as polymers 1 to 8 shown in Table 1 described above.

[0130] <Example 1>

[0131] (Synthesis of Electrode Slurry Additives)

[0132] 40 parts of diisobutyl ketone were placed in a reaction container equipped with a stirring and heating device and a cooling tube, and after nitrogen substitution, the temperature was kept at 80° C. The following monomer mixture was added dropwise over 6 hours.

[0133] <Monomer mixture>

[0134] ·Stearyl methacrylate···40 parts

[0135] (Polymerizable unsaturated monomer that forms a structural unit having a linear alkyl group having 14 or more carbon atoms)

[0136] ·N,N-dimethylaminoethyl methacrylate···2 parts

[0137] (Polymerizable unsaturated monomer forming a structural unit having a basic functional group)

[0138] ·Isobutyl acrylate (other polymerizable unsaturated monomer)···40 parts

[0139] ·Isobutyl methacrylate (other polymerizable unsaturated monomer)···18 parts

[0140] ·2,2'-azobis(isobutyronitrile)···0.3 parts

[0141] (Free Radical Polymerization Initiator)

[0142] After 1 hour from the time when the addition was completed, a solution of 0.5 parts of 2,2'-azobis(isobutyronitrile) (not in the amount in Table 1) dissolved in 10 parts of propylene glycol monomethyl ether was added dropwise thereto over 1 hour. Furthermore, the temperature was further maintained at 80°C for 1 hour. Then, diisobutyl ketone was added so that the solid content became 5%, thereby obtaining a solution of an acrylic resin (a-1; electrode slurry additive).

[0143] The acrylic resin (a-1) is a random copolymer and has a weight average molecular weight of 110,000.

[0144] (Fabrication of all-solid-state batteries)

[0145] -Preparation process-

[0146] Preparation of positive electrode

[0147] In 1 g of butyl butyrate as a solvent, a solution of the acrylic resin (a-1; electrode slurry additive) and a positive electrode active material (LiNi 0.33 Co 0.33 Mn 0.33 O 2) 2 g, carbon material as a conductive additive (VGCF-H manufactured by Resonac Co., Ltd., VGCF is a registered trademark) 0.03 g, sulfide solid electrolyte (Li 2 SP 2 S 5 ) 0.3g, and 0.3g of diisobutyl ketone solution containing 5% by mass of poly(vinylidene fluoride-co-hexafluoropropylene) as a binder, were dispersed for 10 minutes with ultrasound at an amplitude of 40μm and a frequency of 20kHz to obtain a positive electrode slurry. The slurry was applied by a knife to an aluminum foil as a substrate (positive electrode collector) with a spacing of 100μm. It was dried at 100°C for 30 minutes to produce a positive electrode having a positive electrode layer on the positive electrode collector.

[0148] Preparation of negative electrode

[0149] In 2.7 g of diisobutyl ketone as a solvent, a solution of the acrylic resin (a-1; electrode slurry additive), 1 g of a negative electrode active material (Si simple substance), 0.13 g of a carbon material (VGCF-H, manufactured by Resonac Co., Ltd., VGCF is a registered trademark) as a conductive additive, and sulfide solid electrolyte (Li 2 SP 2 S 5 ) 1.2g, and 0.8g of diisobutyl ketone solution containing 5% by mass of poly(vinylidene fluoride-co-hexafluoropropylene) as a binder were dispersed for 10 minutes with ultrasound at an amplitude of 40μm and a frequency of 20kHz to obtain a negative electrode slurry. The slurry was applied by a knife to a nickel foil as a substrate (negative electrode collector) with a gap of 100μm. It was dried at 100°C for 30 minutes to produce a negative electrode having a negative electrode layer on the negative electrode collector.

[0150] Preparation of electrolyte layer

[0151] Li was added to 0.8 g of heptane as a solvent. 2 SP 2 S 5 (sulfide solid electrolyte) 0.4g, and 0.05g of a heptane solution containing 5% by mass of acrylonitrile-butadiene rubber (ABR) as a binder, were dispersed for 10 minutes with ultrasound at an amplitude of 40μm and a frequency of 20kHz to obtain an electrolyte slurry. The obtained slurry was applied by a knife to a stainless steel foil as a substrate with a spacing of 50μm. The coating was dried at 100°C for 30 minutes to prepare an electrolyte layer on the substrate.

[0152] (Lamination process)

[0153] The electrolyte layer was stacked on the negative electrode collector of the negative electrode, and the stainless steel foil as the substrate of the electrolyte layer was removed. The stack of the negative electrode and the electrolyte layer was roll-pressed at a line pressure of 3 t / cm and room temperature. The electrolyte layer was stacked on the positive electrode collector of the positive electrode, and the stainless steel foil as the substrate of the electrolyte layer was removed. The stack of the positive electrode and the electrolyte layer was roll-pressed at a line pressure of 4 t / cm and 170°C. The stack of the negative electrode and the electrolyte layer and the stack of the positive electrode and the electrolyte layer that were roll-pressed were respectively 1 cm 2 The punched-out laminate of the negative electrode and the electrolyte layer and the laminate of the positive electrode and the electrolyte layer are overlapped and joined so that the electrolyte layers are in contact with each other, thereby producing an all-solid-state battery.

[0154] <Examples 2 to 8 and Comparative Examples 1 to 8>

[0155] Except for changing the electrode slurry additives and the like as shown in the following Table 2 or Table 3, the electrode slurry was prepared in the same manner as in Example 1 to produce an all-solid-state battery.

[0156] (Synthesis of Electrode Slurry Additives)

[0157] -Synthesis of polymers (a-2) to (a-6) and polymer (a-8)-

[0158] Except having changed the compounding ratio of the polymerizable unsaturated monomer as shown in Table 2, it carried out similarly to the synthesis|combination of acrylic resin (a-1), and prepared the solution of acrylic resin (electrode slurry additive).

[0159] -Synthesis of polymer (a-7)-

[0160] A solution of an acrylic resin (a-7; electrode slurry additive) was prepared in the same manner as in the synthesis of the acrylic resin (a-1), except that the amount of the initiator was changed from 0.3 parts to 0.6 parts.

[0161] -Synthesis of Comparative Polymer (a-11)-

[0162] A solution of acrylic resin (a-11; electrode slurry additive) was prepared in the same manner as in the synthesis of acrylic resin (a-1), except that the type and amount of the initiator and the synthesis conditions of the polymer (electrode slurry additive) were changed as shown in Table 3.

[0163] -Synthesis of Comparative Polymers (a-12) to (a-18)-

[0164] Except having changed the compounding ratio of the polymerizable unsaturated monomer as shown in Table 3, it carried out similarly to the synthesis|combination of acrylic resin (a-1), and prepared the solution of acrylic resin (electrode slurry additive).

[0165] <Measurement and evaluation>

[0166] -Weight average molecular weight and amine value of electrode slurry additives-

[0167] The weight average molecular weight and amine value of the polymer obtained in each example were measured as described in the above-mentioned sections "·Measurement of weight average molecular weight" and "·Measurement of amine value".

[0168] -Evaluation of slurry particle size-

[0169] The particle size of the obtained negative electrode slurry was measured in accordance with JIS K5600-2-5 (1999). The smaller the particle size value, the higher the dispersion stability of the components in the slurry.

[0170] -Evaluation of resistance value-

[0171] The obtained all-solid-state battery was CCCV charged at a rate of 1 / 3C to 4.35 V, and then discharged at 1 / 3C to 3.35 V. Thereafter, the battery was further discharged at 7C, and the resistance was calculated from the voltage change over 10 seconds.

[0172] Table 2

[0173]

[0174] Table 3

[0175] In Tables 2 and 3, the synthesis temperature in the column of electrode slurry additive synthesis conditions is the temperature in ° C., and the dropping time is expressed in hours (h).

[0176] In Tables 2 and 3, "-" in the column of each component of the electrode slurry means that the component is not used. In addition, "-" in the column of "resistance value" means "cannot be formed into a battery". ">100" in the column of slurry particle size means that the slurry particle size exceeds 100 μm.

[0177] It is clear from the results shown in Tables 2 and 3 that in the examples, the electrode slurry additive improves the dispersion stability of the components of the electrode slurry. In contrast, in Comparative Examples 1 to 3 and Comparative Examples 6 to 8, the dispersibility of the components contained in the electrode slurry is insufficient, and the generation of agglomerates is observed. Therefore, the coating of the electrode slurry on the substrate cannot be carried out, and an all-solid battery cannot be produced. In addition, in Comparative Examples 4 to 5, although a certain degree of dispersion can be performed, the dispersion stability is poor due to the high slurry particle size, and the resistance value cannot be suppressed to a low level.

Claims

1. An electrode slurry additive, which is an acrylic resin containing a structural unit having a linear alkyl group with 14 or more carbon atoms and a structural unit having a basic functional group, The weight average molecular weight is more than 50,000 and less than 200,000, The amine value is 5 mgKOH / g or more and 33 mgKOH / g or less. 2 . The electrode slurry additive according to claim 1 , wherein the content ratio of the structural unit having a linear alkyl group having 14 or more carbon atoms is 30% by mass or more and 65% by mass or less based on the entire structural units contained in the acrylic resin. 3 . The electrode slurry additive according to claim 1 , wherein the content ratio of the structural unit having a basic functional group is 0.5% by mass or more and 10% by mass or less relative to the entire structural units contained in the acrylic resin. The electrode slurry additive according to claim 1 , which is a random polymer. 5 . A solid battery comprising the electrode slurry additive according to claim 1 .

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