Conductive material dispersion for secondary battery and slurry composition comprising same for secondary battery electrode

Abstract

The present invention relates to a conductive material dispersion for a secondary battery and a slurry composition comprising same for a secondary battery electrode. Specifically, a conductive material dispersion having superior performance to existing dispersants by containing a vinyl-based dispersant can be used for a secondary battery electrode.

Description

Conductive material dispersion for secondary batteries and slurry composition for secondary battery electrodes containing the same

[0001] The present invention relates to a conductive dispersion for secondary batteries and a slurry composition for secondary battery electrodes comprising the same. Specifically, the conductive dispersion, which includes a vinyl-based dispersant and exhibits superior performance to existing dispersants, can be used in secondary battery electrodes.

[0002] Japanese patent JP 6804806 B2 discloses a method for dispersing a conductive material in a dispersion medium, but the invention is not optimized for dispersing conductive materials. Furthermore, EP 3770204 A1 defines the structure of the dispersant as a polymer containing aromatic vinyl monomer units and straight-chain alkylene structural units of at least 4 carbon atoms. However, this structure presents a problem in that it is not suitable for dispersing conductive materials with hydroxyl groups on the surface.

[0003] Chinese patent CN 114583163 A provides a dispersant for a lithium-ion battery, a method for preparing the same, a cathode slurry, and a lithium-ion battery. The dispersant comprises a structural unit derived from the N-vinyl pyrrolidone monomer. While dispersants copolymerized with N-vinyl pyrrolidone offer advantages over conventional dispersants in dispersing conductive agents, there is a significant need for further improvement in their effectiveness.

[0004] (Patent Document 1) JP 6801806 B2

[0005] (Patent Document 2) EP 3770204 A1

[0006] (Patent Document 3) CN 114583163 A

[0007] The purpose of the present invention is to provide a conductive material dispersion liquid that improves electrical connection by inducing uniform dispersion in a negative electrode slurry of a secondary battery through the structure of a dispersant that facilitates dispersion of conductive materials such as carbon nanotubes, graphene, and carbon black in a medium, thereby increasing the lifespan and efficiency of the secondary battery.

[0008] In addition, a conductive material pre-dispersed slurry for secondary battery electrodes with improved conductive material dispersion characteristics can be realized. In particular, the purpose is to provide a conductive material pre-dispersed slurry for secondary battery electrodes that has a relatively high conductive material content, relatively low viscosity, and can be easily manufactured using a relatively simple process.

[0009] In addition, the present invention aims to manufacture an electrode having excellent performance by applying the above-described conductive dispersion slurry, and to provide a secondary battery using the above-described electrode.

[0010] According to the first aspect of the present invention,

[0011] A dispersant is provided, which is a terpolymer polymer, comprising: a first repeating unit derived from polyvinyl containing morpholine as a functional group; a second repeating unit derived from polyvinyl containing an organic acid or an organic acid salt as a functional group; and a third repeating unit derived from polyvinyl containing an aromatic group as a functional group.

[0012] According to one embodiment of the present invention, the first repeating unit may be a vinyl monomer derived from (meth)acrylomorpholine.

[0013] According to one embodiment of the present invention, the organic acid or organic acid salt of the second repeating unit may be at least one selected from the group consisting of unsaturated sulfonic acid, unsaturated phosphoric acid, unsaturated carboxylic acid, and salts thereof.

[0014] According to one embodiment of the present invention, the organic acid or organic acid salt of the second repeating unit is selected from the group consisting of sodium allyl sulfonate, sodium (methyl)allyl sulfonate, 2-(meth)acrylamide-2-methylpropane sulfonate, sodium styrene sulfonate, sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, 2-methyl-2-(meth)acrylic acid-2-sulfonate ethyl ester, potassium 3-sulfopropyl (meth)acrylate, potassium 3-sulfopropyl (meth)acrylate, vinyl phosphonic acid, (1-phenylvinyl) phosphonic acid, allyl phosphonic acid, bis[2-(methacryloxy)ethyl] phosphoric acid, 2-(methacryloxy)ethyl-2-(trimethylamino)ethyl phosphate, 2-methyl-2-propenoic acid 2-(phosphonooxy)ethyl ester, It may be at least one selected from the group consisting of (meth)acrylic acid, beta-carboxyethyl (meth)acrylate, 2-ethyl (meth)acrylic acid, α-acetoxy (meth)acrylic acid, butenoic acid, crotonic acid, maleic acid, itaconic acid, and fumaric acid.

[0015] According to one embodiment of the present invention, the third repeating unit may be a vinyl monomer containing a benzene ring.

[0016] According to one embodiment of the present invention, the aromatic group of the third repeating unit may be at least one selected from the group consisting of styrene, alpha styrene, vinyl toluene, 1-methoxy 4-vinylbenzene, 1-ethoxy 4-vinylbenzene, 1-(t-butyl)-4-vinylbenzene, 1,3,5-trimethyl-2-vinylbenzene, and 1,3,5-trichloro-2-vinylbenzene.

[0017] According to one embodiment of the present invention, the dispersant may be of the following chemical formula 1.

[0018] [Chemical Formula 1]

[0019]

[0020] R1 to R3 in the above chemical formula 1 may each independently be hydrogen or methyl.

[0021] The above R4 is an aliphatic or aromatic hydrocarbon group containing or not containing a heteroatom of 1 to 20 carbon atoms, linear, branched, or cyclic, with or without an unsaturated group,

[0022] The above R5 is selected from at least one functional group consisting of sulfuric acid, phosphoric acid and carboxylic acid groups and salts of the sulfuric acid, phosphoric acid and carboxylic acid groups,

[0023] The above R6 to R10 independently include at least one of a linear, branched, or cyclic aliphatic or aromatic hydrocarbon group containing or not containing hydrogen or an unsaturated group and containing or not containing a heteroatom having 1 to 20 carbon atoms, or a halogen element,

[0024] The above l is 0.01 to 0.95,

[0025] The above m is 0.04 to 0.60,

[0026] The above n is 0.01 to 0.40,

[0027] The sum of the above l, m and n is 1.

[0028] According to one embodiment of the present invention, the dispersant of the chemical formula 1 may be represented by the following chemical formulas 2 to 7.

[0029] [Chemical Formula 2]

[0030]

[0031] [Chemical Formula 3]

[0032]

[0033] [Chemical Formula 4]

[0034]

[0035] [Chemical Formula 5]

[0036]

[0037] [Chemical Formula 6]

[0038]

[0039] [Chemical Formula 7]

[0040]

[0041] In the above chemical formulas 2 to 7,

[0042] The above l is 0.01 to 0.95,

[0043] The above m is 0.04 to 0.60,

[0044] The above n is 0.01 to 0.40,

[0045] The sum of the above l, m and n is 1.

[0046] According to one embodiment of the present invention, the number average molecular weight (Mn) of the dispersant may be 3,000 to 50,000 g / mol.

[0047] According to the second aspect of the present invention,

[0048] A conductive material dispersion for a secondary battery is provided, comprising the above dispersant, conductive material, and dispersion medium.

[0049] According to one embodiment of the present invention, the dispersion may further include an amine compound.

[0050] According to one embodiment of the present invention, the amine compound may be at least one selected from the group consisting of methylamine, ethylamine, propylamine, butylamine, hexylamine, heptylamine, octylamine, dioctylamine, trioctylamine, t-octylamine, aminoethanol, aminopropanol, aminobutanol, aminopentanol, aminohexanol, dodecylamine, octadecylamine, tripropylamine, N,N-dimethylbenzylamine, 2-methoxyethylamine, and oleylamine.

[0051] According to one embodiment of the present invention, the conductive material may be at least one selected from the group consisting of carbon nanotubes, graphene oxide, graphene nanoplates, carbon black, and reduced graphene oxide.

[0052] According to one embodiment of the present invention, the dispersion medium may be at least one selected from the group consisting of n-methyl-2-pyrrolidone, dimethylformamide, dimethylsulfoxide, xylene, toluene, hexane, heptane, octane, cyclohexane, cyclohexanone, ethyl acetate, propyl acetate, butyl acetate, methanol, ethanol, butanol, isopropyl alcohol, glycerol, isobutanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-methoxy propanol, tetrahydrofuran, formic acid, acrylonitrile, glycol ether, and water.

[0053] According to one embodiment of the present invention, the dispersion may further include at least one of smectite clay and a cellulose-based compound.

[0054] According to one embodiment of the present invention, the cellulose compound may be at least one selected from the group consisting of methylcellulose, ethylcellulose, hydroxyethylcellulose, benzylcellulose, tritylcellulose, cyanoethylcellulose, carboxymethylcellulose, carboxyethylcellulose, aminoethylcellulose, nitrocellulose, cellulose ether, and carboxymethylcellulose sodium salt.

[0055] According to one embodiment of the present invention, the content of the dispersant may be included in an amount of 1 to 5 wt% relative to the total content of the dispersion.

[0056] According to one embodiment of the present invention, the content of the conductive agent may be included in an amount of 1 to 10 wt% relative to the total content of the dispersion.

[0057] According to the third aspect of the present invention,

[0058] A negative electrode slurry composition for a secondary battery is provided, comprising the above dispersion, a negative electrode active material, a thickener, a binder, and a solvent.

[0059] According to one embodiment of the present invention, the negative active material may include SiOX (0≤X≤2) and a carbon-based active material.

[0060] According to the dispersant of the present invention, uniform dispersion in the negative electrode slurry of a secondary battery can be induced, thereby improving electrical connection and increasing the lifespan and efficiency of the secondary battery.

[0061] In addition, since the content of the conductive material included in the conductive material pre-dispersed slurry for secondary battery electrodes is relatively high and has relatively low viscosity, secondary battery electrodes can be easily manufactured through a simple process.

[0062] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0063] When a part in this specification is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0064] Hereinafter, preferred embodiments of the present invention will be described in detail.

[0065]

[0066] A dispersant according to one embodiment of the present invention can be manufactured by polymerizing the first to third repeating units.

[0067] Specifically, the dispersant according to one embodiment of the present invention may be a terpolymer polymer including a first repeating unit derived from polyvinyl containing morpholine as a functional group; a second repeating unit derived from polyvinyl containing an organic acid or an organic acid salt as a functional group; and a third repeating unit derived from polyvinyl containing an aromatic group as a functional group.

[0068] In a dispersant according to one embodiment of the present invention, the first repeating unit may be derived from polyvinyl containing morpholine as a functional group.

[0069] That is, the first repeating unit (first monomer) may include a morpholine (meth)acrylic monomer having a tertiary amine group and an ether group, which are hydrophilic groups, and the tertiary amine and ether groups may improve the dispersibility of nanoparticles through hydrogen bonding with a base composed of an acid and an acid-base group. Specifically, it may be (meth)acrylomorpholine.

[0070] In a dispersant according to one embodiment of the present invention, the second repeating unit may be derived from polyvinyl containing an organic acid or an organic acid salt as a functional group.

[0071] The above second repeating unit (second monomer) may be a vinyl monomer having a polyvinyl structure main chain containing sulfuric acid, phosphoric acid, and carboxylic acid groups and salts of the sulfuric acid, phosphoric acid, and carboxylic acid groups as functional groups. Specifically, the organic acid or organic acid salt of the second repeating unit is selected from the group consisting of sodium allyl sulfonate, sodium (methyl)allyl sulfonate, 2-(meth)acrylamide-2-methylpropane sulfonate, sodium styrene sulfonate, sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, 2-methyl-2-(meth)acrylic acid-2-sulfonate ethyl ester, potassium 3-sulfopropyl (meth)acrylate, potassium 3-sulfopropyl (meth)acrylate, vinyl phosphonic acid, (1-phenylvinyl) phosphonic acid, allyl phosphonic acid, bis[2-(methacryloxy)ethyl] phosphoric acid, 2-(methacryloxy)ethyl-2-(trimethylamino)ethyl phosphate, 2-methyl-2-propenoic acid 2-(phosphonooxy)ethyl ester, At least one of (meth)acrylic acid, beta-carboxyethyl (meth)acrylate, 2-ethyl (meth)acrylic acid, α-acetoxy (meth)acrylic acid, butenoic acid, crotonic acid, maleic acid, itaconic acid, and fumaric acid may be selected. However, the present invention is not limited thereto, and any vinyl monomer containing sulfuric acid, phosphoric acid, and carboxylic acid groups and salts of the sulfuric acid, phosphoric acid, and carboxylic acid groups may be used as the second monomer.

[0072] The tertiary amine and ether of the (meth)acrylomorpholine functional group of the sulfuric acid, phosphoric acid and carboxylic acid groups of the second repeating unit and the salt polymer of the sulfuric acid, phosphoric acid and carboxylic acid groups can serve to facilitate bonding with the conductive material while existing in a salt form.

[0073] In a dispersant according to one embodiment of the present invention, the third repeating unit may be derived from polyvinyl containing an aromatic group as a functional group.

[0074] The third repeating unit may lower the polarity of the dispersant by using a vinyl monomer containing a benzene ring depending on the polarity of the medium during dispersion. Therefore, since the third repeating unit is a vinyl monomer containing a benzene ring, it may play a role in increasing the reliability of the secondary battery, such as the withstand voltage characteristics. Specifically, the aromatic group of the third repeating unit may be selected from at least one group selected from the group consisting of styrene, alpha styrene, vinyl toluene, 1-methoxy 4-vinylbenzene, 1-ethoxy 4-vinylbenzene, 1-(t-butyl)-4-vinylbenzene, 1,3,5-trimethyl-2-vinylbenzene, and 1,3,5-trichloro-2-vinylbenzene.

[0075] A dispersant according to one embodiment of the present invention may be represented by the following chemical formula 1.

[0076]

[0077] [Chemical Formula 1]

[0078]

[0079] R1 to R3 in the above chemical formula 1 may each independently be hydrogen or methyl.

[0080] The above R4 is an aliphatic or aromatic hydrocarbon group containing or not containing a heteroatom of 1 to 20 carbon atoms, linear, branched, or cyclic, with or without an unsaturated group,

[0081] The above R5 is selected from at least one functional group consisting of sulfuric acid, phosphoric acid and carboxylic acid groups and salts of the sulfuric acid, phosphoric acid and carboxylic acid groups,

[0082] The above R6 to R10 independently include at least one of a linear, branched, or cyclic aliphatic or aromatic hydrocarbon group containing or not containing hydrogen or an unsaturated group and containing or not containing a heteroatom having 1 to 20 carbon atoms, or a halogen element,

[0083] The above l is 0.01 to 0.95,

[0084] The above m is 0.04 to 0.60,

[0085] The above n is 0.01 to 0.40,

[0086] The sum of the above l, m and n is 1.

[0087]

[0088] The dispersant according to one embodiment of the present invention may be a vinyl-based dispersant specifically defined by the following chemical formulas 2 to 7.

[0089] [Chemical Formula 2]

[0090]

[0091] [Chemical Formula 3]

[0092]

[0093] [Chemical Formula 4]

[0094]

[0095] [Chemical Formula 5]

[0096]

[0097] [Chemical Formula 6]

[0098]

[0099] [Chemical Formula 7]

[0100]

[0101] In the above chemical formulas 2 to 7,

[0102] The above l is 0.01 to 0.95,

[0103] The above m is 0.04 to 0.60,

[0104] The above n is 0.01 to 0.40,

[0105] The sum of the above l, m and n is 1.

[0106]

[0107] The above vinyl resin can be manufactured by appropriately selecting a known manufacturing method, such as solution polymerization, bulk polymerization, emulsion polymerization, or various radical polymerizations. Preferably, it can be manufactured using a solution polymerization method.

[0108] The above vinyl resin can be manufactured as a random copolymer, a block copolymer, or a graft copolymer. Preferably, it can be manufactured as a random copolymer. This is because it is advantageous to manufacture it as a random copolymer from a cost and process perspective.

[0109] In the above solution polymerization, it is preferable to use the same solvent as the dispersion medium as the polymerization solvent. Specifically, the polymerization solvent is the same as the dispersion medium, and may be one or two or more selected from n-methyl-2-pyrrolidone, dimethylformamide, dimethylsulfoxide, xylene, toluene, hexane, heptane, octane, cyclohexane, cyclohexanone, ethyl acetate, propyl acetate, butyl acetate, methanol, ethanol, butanol, isopropyl alcohol, glycerol, isobutanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-methoxy propanol, tetrahydrofuran, formic acid, acrylonitrile, glycol ether, and water.

[0110] According to one embodiment of the present invention, the dispersant may have a molar ratio of the first repeating unit (first monomer) of 0.1 to 0.95. Preferably, the molar ratio of the first repeating unit may be 0.30 to 0.9. More preferably, the molar ratio of the first repeating unit may be 0.4 to 0.8. If the molar ratio of the first repeating unit is 0.4 or less, the dispersibility with the conductive material may be poor, and if it is 0.8 or more, the mechanical properties may be deteriorated during the manufacture of the medium and electrode.

[0111] The molar ratio of the second repeating unit (second monomer) may be 0.01 to 0.40. Preferably, the molar ratio of the second repeating unit may be 0.1 to 0.35. More preferably, the molar ratio of the second repeating unit may be 0.15 to 0.3. If the molar ratio of the second repeating unit is 0.15 or less, it may be difficult to form a salt with a basic compound, which may cause a problem of reduced dispersibility with the conductive agent. If the molar ratio of the second repeating unit is 0.3 or more, the dispersant resin may precipitate, causing a problem of losing its function as a dispersant.

[0112] The molar ratio of the third repeating unit (third monomer) may be 0 to 0.25. Preferably, the molar ratio of the third repeating unit may be 0.10 to 0.20. If the molar ratio of the third repeating unit is 0.1 or less, a problem of deterioration in mechanical properties may occur during electrode manufacturing. If the molar ratio of the third repeating unit is 0.2 or more, a problem of deterioration in conductive material and dispersibility may occur.

[0113] The above solution polymerization can be carried out at 50°C to 150°C for 5 to 30 hours by adding a polymerization initiator under an inert gas atmosphere.

[0114] The above inert gas may include, but is not limited to, argon and nitrogen.

[0115] The polymerization initiator, chain transfer agent, and emulsifier used in the above radical polymerization can be appropriately selected from widely known substances.

[0116] According to one embodiment of the present invention, the dispersant may be a vinyl-based dispersant resin. The average molecular weight of the vinyl-based dispersant resin can be controlled by the amount of polymerization initiator and chain transfer agent used, and reaction conditions. Furthermore, the amounts used can be appropriately adjusted depending on the type of polymerization initiator and chain transfer agent.

[0117] The above polymerization initiator may be one or two phases selected from the group of azo initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-amidinopropane)dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane]dihydrochloride, 2,2'-azobis(2-methylpropionamidine)disulfate, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropion amidine]hydrate.

[0118] The above polymerization initiator is one or two or more selected from peroxide-based initiators such as persulfates such as potassium persulfate and ammonium persulfate, di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butyl peroxyneo decanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di(t-hexylperoxy)cyclohexane, t-butyl hydroperoxide, and hydrogen peroxide. Can be.

[0119] Additionally, the polymerization initiator may include a redox initiator combining a peroxide and a reducing agent, such as a combination of a persulfate and sodium bisulfite, or a combination of a peroxide and sodium ascorbate, but is not limited thereto.

[0120] The above polymerization initiator may be used alone or in combination of two or more. The amount of the polymerization initiator is preferably 1 to 15 parts by weight based on 100 parts by weight of the total amount of the monomer components. More preferably, it may be 3 to 10 parts by weight.

[0121] The average molecular weight of the vinyl dispersant of the resin can be controlled depending on the amount of the polymerization initiator. As the amount of the polymerization initiator increases, the average molecular weight decreases, and conversely, as the amount of the polymerization initiator decreases, the number average molecular weight increases.

[0122] The average molecular weight of the vinyl-based dispersant that is effective in the present invention may be 3,000 to 50,000 in terms of number average molecular weight (Mn). To produce a dispersant having the above number average molecular weight, it is preferable to use an amount of polymerization initiator within the above range.

[0123]

[0124] A conductive dispersion according to one embodiment of the present invention may include a dispersant, a conductive material, and a dispersion.

[0125] The above dispersant may be a terpolymer polymer including a first repeating unit derived from polyvinyl containing morpholine as a functional group as described above; a second repeating unit derived from polyvinyl containing an organic acid or an organic acid salt as a functional group; and a third repeating unit derived from polyvinyl containing an aromatic group as a functional group.

[0126] The dispersant may be included in an amount of 1 to 5 wt% based on the total content of the dispersion, and preferably 2 to 4 wt%. If the content of the dispersant is lower than 1 wt% or higher than 5 wt%, a problem of deteriorated cell performance may occur.

[0127] The above-mentioned conductive material can be a carbon material used as an anode material for lithium-ion secondary batteries. Carbon materials have the advantage of a low potential close to that of lithium and a high charge-discharge capacity per unit mass.

[0128] The conductive material may include carbon black, Ketjen black, fullerene, graphene, carbon nanotubes, and carbon nanofibers. Preferably, the conductive material may be a carbon nanotube. By adding the carbon nanotube to an anode including graphite and silicon, electrode resistance can be reduced, the load resistance of the battery can be improved, the strength of the electrode can be improved, and the expansion and contraction properties of the electrode can be improved. In addition, the cycle life of the lithium secondary battery can be improved.

[0129] The average particle diameter of the above carbon nanotubes may be 3 to 20 μm. The above carbon nanotubes may include single-walled carbon nanotubes and multi-walled carbon nanotubes.

[0130] The above-mentioned conductive material may include graphene. The graphene may include graphene oxide, reduced graphene oxide, and graphene nanoplates.

[0131] The above conductive material may include carbon black. The carbon black may include commonly used super P Conductive CarbonBlack, Ketjen Black, and Denka Black.

[0132] The conductive agent may be included in an amount of 1 to 10 wt% relative to the total content of the dispersion, preferably 3 to 8 wt%, and more preferably 4 to 7 wt%. If the content of the conductive agent is lower than 1 wt% or higher than 10 wt%, cell performance may deteriorate.

[0133] The above dispersion medium may include a polar solvent or a non-polar solvent. The polar solvent may include water. The non-polar solvent may be used in an all-solid-state secondary battery. Specifically, the dispersion medium may be one or two or more selected from the group consisting of n-methyl-2-pyrrolidone, dimethylformamide, dimethylsulfoxide, xylene, toluene, hexane, heptane, octane, cyclohexane, cyclohexanone, ethyl acetate, propyl acetate, butyl acetate, methanol, ethanol, butanol, isopropyl alcohol, glycerol, isobutanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-methoxy propanol, tetrahydrofuran, formic acid, acrylonitrile, glycol ether, and water.

[0134] A method for producing a conductive dispersion according to one embodiment of the present invention may include a step of mixing and stirring a preparatory single-walled carbon nanotube, a dispersant, and a dispersion medium. The dispersant may include a vinyl-based dispersant produced from the first to third monomers.

[0135] It is recommended to use 1 to 30 parts by weight of the dispersant, preferably 10 to 20 parts by weight, based on 100 parts by weight of the total dispersion. If the amount is below the above range, it may be difficult to disperse the conductive agent, causing the conductive agent to precipitate or the dispersion to thicken. If the amount is above the above range, the electrical properties may deteriorate.

[0136] It is recommended to use 0.1 to 10 parts by weight of the conductive agent, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the total dispersion. Below the above range, the electrical properties are low, making it difficult to use as a cathode. Above the above range, the dispersibility is reduced, the viscosity increases, and the conductive agent agglomeration problem occurs, making it difficult to produce a high-quality conductive agent dispersion.

[0137] It is recommended to use 60 to 99 parts by weight of the dispersion medium, preferably 70 to 90 parts by weight, based on 100 parts by weight of the entire dispersion. Below the above range, dispersibility deteriorates, viscosity increases, and agglomeration of the conductive material occurs, making it difficult to manufacture a high-quality negative electrode material. Above the above range, electrical properties deteriorate, making it difficult to use as a negative electrode material.

[0138] Agitation for dispersion may be performed through at least one of mixing and milling using a mixer. The mixing may be performed using a sawtooth mixer such as a homogenizer, a universal stirrer, a clear mixer, or a fill mixer. The mixing may be performed at a rotation speed of 3,500 rpm to 4,500 rpm.

[0139] The above milling can be performed by a method such as a ball mill, a bead mill, a basket mill, an attrition mill, etc., and can be preferably performed by a milling method using a bead mill. When milling by the bead mill, the size of the bead mill can be appropriately determined according to the type and amount of the conductive material and the type of the dispersant, and specifically, the diameter of the bead mill can be 500 μm to 1000 μm, more specifically, 500 mm to 800 μm. In addition, the bead milling process can be performed at a speed of 2,000 rpm to 4,500 rpm, and more specifically, can be performed at a speed of 2,000 rpm to 3,000 rpm.

[0140]

[0141] A conductive dispersion for a secondary battery according to one embodiment of the present invention may further include an amine compound in addition to the vinyl-based dispersant. By using the vinyl-based dispersant and the amine compound simultaneously, dispersion stability can be maximized.

[0142] By forming a salt form between the acid and amine compounds of the vinyl-based dispersant, the dispersibility of a conductive material having a hydrophilic surface is increased, thereby increasing the amount of the conductive material in the dispersion of the negative electrolyte, thereby increasing the charging capacity of the secondary battery.

[0143] The above amine compound may be selected from a primary amine, a secondary amine, a tertiary amine, an aromatic amine, or a mixture thereof. However, the present invention is not limited thereto, and any type of primary amine, secondary amine, tertiary amine, or aromatic amine commonly used in this field may be used without any problem.

[0144] Specifically, the amine compound may be one or two or more selected from methylamine, ethylamine, propylamine, butylamine, hexylamine, heptylamine, octylamine, dioctylamine, trioctylamine, t-octylamine, aminoethanol, aminopropanol, aminobutanol, aminopentanol, aminohexanol, dodecylamine, octadecylamine, tripropylamine, N,N-dimethylbenzylamine, 2-methoxyethylamine, and oleylamine.

[0145] The above amine compound may be used by mixing it in advance with the vinyl dispersant to form a salt, or may be used together with a conductive agent during dispersion. However, it is preferable to mix it in advance with the vinyl dispersant to form a sufficient salt.

[0146] The above amine system may be present in an amount of 10 to 60 parts by weight, preferably 20 to 50 parts by weight, based on the solid content of the vinyl dispersant, based on 100 parts by weight.

[0147] If it is below the above range, the dispersibility may decrease and the amount of conductive material may decrease, and if it is above the above range, it may have a negative effect on the properties of the secondary battery.

[0148] The acid value of the above amine compound and vinyl copolymer dispersant mixture measured by the solid content-based terminal group analysis method may be in the range of 1 to 10 mg KOH / g, and the amine value may be in the range of 2 to 10 mg KOH / g.

[0149]

[0150] The conductive dispersion for a secondary battery according to one embodiment of the present invention can be used together with smectite clay in addition to the vinyl-based dispersant.

[0151] The above smectite clay is a 2:1 silicate clay mineral with a high surface charge and a large surface area because it has a two-dimensional space with great anisotropy, a large number of substitutions within the unit structure, and a thin piece form, and has a high CEC (cation exchange capacity) and a large interlayer expansion property.

[0152] The structure of smectite is composed of Si-O tetrahedron and Al-O octahedron layers in a 2:1 ratio, with alumina partially substituting for silica in the Si-O tetrahedron, and iron or magnesium partially substituting for aluminum in the Al-O octahedron layers. This results in a state with few cations, and monovalent cations are adsorbed on the surface to balance the overall charge. If the monovalent cation adsorbed at this time is sodium, it appears as sodium montmorillonite.

[0153] Smectite clays are generally called bentonites, and representative examples include montmorillonite (MMT), nontronite, saponite, hectorite, and stevensite, and the most representative example is sodium montmorillonite (Na + -MMT). The basic structure of smectite clay is a combination of silica tetrahedral sheets and alumina octahedral sheets, and there are various structures depending on the composition ratio of tetrahedrons and octahedrons.

[0154] Representative clays with this structure include Kaolin-serpentine, Pyrophyllite-Talc, mica, smectite, vermiculite, and chlorite. Among these, smectite species are further divided into montmorillonite (MMT), nontronite, saponite, and hectorite.

[0155] Cray Na + -MMT is usually composed of a single alumina octahedral sheet layer sandwiched between two silica tetrahedral sheets, with each layer being approximately 1 nm thick and the overall size varying from several microns to 30 nm. Van der Waals forces form between these layers. Charges within a layer are formed when cations in the alumina sheets are replaced by other types of cations. For example, when Al3+ ions are replaced by Mg2+ or Fe2+, the layer becomes negatively charged. Therefore, to maintain overall charge balance, exchangeable cations and water molecules are contained between the silicate layers.

[0156] MMT can increase its volume through swelling within its crystals. This high swelling property has led to its widespread industrial applications. MMT possesses the unique property of swelling simply by adding water, making it suitable as a host layer for interlayer cross-linked nanocomposites. It is being considered an important new material with diverse physical properties.

[0157] Na + -It has been known that montmorillonite contains water molecules between the silicate layers, so it is easy for water to swell, but other organic substances cannot penetrate between the layers.

[0158] Since clay generally has hydrophilic properties, it is used to manufacture complexes with polymers after being organicized through appropriate surface treatment. This organicization technology of clay can be said to be the most crucial technology in determining the properties of polymer nanocomposites.

[0159] In the case of montmorillonite, which is commonly used to organicize clay, it is advantageous to understand the swelling process of clay in order to control the organicization reaction of clay in an aqueous solution.

[0160] Montmorillonite appears in regions 1, 2, and 3 depending on the concentration in aqueous solution. In region 1, the overall crystal form is maintained in the aqueous system, but the interplanar spacing increases from 1 nm to 2.2 nm. This is due to the hydration phenomenon of cations existing between clay layers.

[0161] On the other hand, in the case of montmorillonite containing monovalent ions such as Li+ or Na+, more swelling occurs, which is called region 2. That is, a repulsive force is generated by the electric double layer between the clay surfaces, which is greater than the van der Waals force between the clay sheets, allowing the separation of the clay sheets. At this time, since the interaction between the ends of the clay sheets and the surface is dominant, it exhibits behavior like a paste or gel. When the water content increases beyond region 2, the interaction between the ends of the clay sheets and the surface is eliminated, and this state is called region 3.

[0162] The attractive forces acting between the smectite clay surface and organic matter include cationic bonding, ion-dipole bonding, dipole-dipole interaction, and ð-bonding. It can be confirmed that the hydrophilic vinyl-based dispersant used in the present invention is ion-exchanged to facilitate dispersion with the conductive agent, thereby lowering the viscosity of the dispersion. It is preferable that the amount of smectite clay be 0.01 to 0.1 parts by weight, and preferably 0.02 to 0.05 parts by weight, per 100 parts by weight of the conductive agent. If the amount is less than the above content, the viscosity of the dispersion may be high, and if it is more than the above range, it may have a negative effect on the properties of the secondary battery.

[0163] The conductive dispersion for a secondary battery according to one embodiment of the present invention can be used together with a cellulose-based compound in addition to the vinyl-based dispersant.

[0164] Dispersibility can be improved by adding the above vinyl-based dispersant and the above cellulose-based compound. It is preferable to add 50 to 800 parts by weight of the cellulose-based compound, preferably 100 to 400 parts by weight, based on the solid content of the vinyl-based dispersant. Below the above range, the particle size of the conductive material may increase, and above the above range, the dispersibility of the conductive material may decrease.

[0165] The weight-average molecular weight (Mw) of the above cellulose compound may be 50,000 to 450,000 g / mol or less. Preferably, it may be 120,000 g / mol or less. More preferably, it is good to use a cellulose compound having a molecular weight of 50,000 to 120,000 g / mol. If it is less than 50,000 g / mol, the dispersibility may be poor and the viscosity of the dispersion may be high, and if it is above the above range, the coating property of the electrode slurry may be poor and electrode formation may be difficult.

[0166] In addition, the esterification degree of the cellulose compound used in the embodiment of the present invention may be about 0.6 to 1.0. In CMC (carboxymethyl cellulose), which is one of the cellulose compounds, three functional groups exist in one monomer, and the esterification degree of the cellulose compound indicates the degree to which a hydroxyl group among the functional groups is substituted with an ester group (i.e., the degree of substitution). The esterification degree of the cellulose compound may have a range of 0 to 3.

[0167] According to one embodiment of the present invention, the degree of esterification of CMC (carboxymethyl cellulose), which is one of the cellulose compounds, may be about 0.6 to 1.0, preferably about 0.7 to 0.9. As the degree of esterification of CMC increases, the hydrophilicity of CMC may increase. When the degree of esterification is less than 0.6, the degree of hydration may be too low to mix well with a polar dispersion medium, and when the degree of esterification exceeds 1.0, the dispersibility with a conductive material may be reduced.

[0168] Specifically, the cellulose compound may be one or two or more selected from the group consisting of methylcellulose, ethylcellulose, hydroxyethylcellulose, benzylcellulose, tritylcellulose, cyanoethylcellulose, carboxymethylcellulose, carboxyethylcellulose, aminoethylcellulose, nitrocellulose, cellulose ether, and carboxymethylcellulose sodium salt.

[0169]

[0170] The negative electrode slurry according to one embodiment of the present invention may include the above-prepared dispersion, negative electrode active material, thickener, binder, and solvent.

[0171] The above negative active material is SiO X (0≤X≤2) and may include a carbon-based active material. The SiOX (0≤X≤2) may be a form containing Si and SiO2. That is, the x above is the SiO X (0≤X≤2) corresponds to the number ratio of O to Si included in the above SiO X When (0≤X≤2) is included, the discharge capacity of the secondary battery can be improved. The SiO X The average particle diameter (D50) of the SiO may be 5 ㎛ to 15 ㎛, and specifically 8 ㎛ to 12 ㎛. When the above range is satisfied, the SiO X The side reaction between the electrolyte and the SiO is suppressed, X Oxidation can be controlled to prevent initial efficiency decline.

[0172] The above SiO X By including this negative active material, the capacity of the battery can be greatly improved. However, the SiO X Compared to graphite, etc., the conductivity is low, and there may be a disadvantage in that the volume expands excessively during charging / discharging of the battery, making it difficult to maintain a conductive path between the negative electrode active materials. To solve this problem, in one embodiment of the present invention, a specific conductive dispersion containing single-walled carbon nanotubes is used. When the conductive dispersion of the present invention is used, the single-walled carbon nanotubes can be uniformly dispersed within the negative electrode active material layer, and since the single-walled carbon nanotubes are relatively thinner than conventional multi-walled carbon nanotubes, electrical connection between the negative electrode active materials can be easily maintained despite the volume expansion of the SiOX. Accordingly, the life and efficiency characteristics of the battery can be improved.

[0173] The above carbon-based active material may be at least one selected from the group consisting of artificial graphite, natural graphite, and graphitized mesocarbon microbeads, and preferably artificial graphite.

[0174] The thickener may be one or two or more selected from the group consisting of carboxymethyl cellulose (CMC), carboxyethyl cellulose, starch, regenerated cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and polyvinyl alcohol.

[0175] The above binder may be one or two or more selected from the group consisting of various types of binder polymers, such as polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber, polyacrylic acid, and polymers in which hydrogens of these are substituted with Li, Na, Ca, etc., or various copolymers.

[0176] According to another embodiment, the present invention may include a conductive dispersion for a secondary battery positive electrode or negative electrode. When used as a conductive dispersion for a positive electrode, the conductive dispersion may include a conductive material, a dispersant, an amine compound, and a dispersion medium. Preferably, the conductive dispersion for a secondary battery positive electrode may include CNT as a conductive material, a vinyl-based dispersant manufactured from the first to third repeating units as a dispersant, and NMP as a dispersion medium.

[0177] When used as a conductive material dispersion for a secondary battery anode, it may contain a conductive material, a dispersant, and a dispersion medium. The conductive material dispersion for a secondary battery anode may contain a conductive material, a dispersant, a cellulose compound, and a dispersion medium. In addition, the dispersion for a secondary battery anode may contain a conductive material, a dispersant, smectite clay, and a dispersion medium. Specifically, the conductive material may contain CNT, the dispersant may contain a vinyl-based dispersant manufactured from the first to third repeating units, and the dispersion medium may contain H2O.

[0178]

[0179] A method for manufacturing a dispersant according to one embodiment of the present invention can be manufactured by polymerizing the first to third repeating units described above. The description of the first to third repeating units is as described above.

[0180] The polymerization method may be appropriately selected from known manufacturing methods such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations. Preferably, the polymerization method is used.

[0181] A method for manufacturing a conductive material slurry for a secondary battery cathode according to one embodiment of the present invention may include a step of controlling the particle size of carbon nanotubes through a ball milling process, a step of manufacturing a conductive material dispersion by stirring the vinyl-based dispersant, the amine-based compound, the dispersion medium, and the carbon nanotubes at room temperature, and a step of subjecting the mixture to high pressure 2 to 5 times using a diamond cell in a high-pressure disperser.

[0182] The ball milling process may include a wet ball mill or a dry ball mill. The stirring may be performed at room temperature at 300 to 800 RPM for 2 to 4 hours. The dispersion medium may include NMP. The high pressure may be a pressure of 500 to 2,000 MPa.

[0183] A method for manufacturing a conductive material slurry for a secondary battery negative electrode according to one embodiment of the present invention may include a step of controlling the particle size of carbon nanotubes through a ball milling process, a step of manufacturing a conductive material dispersion by stirring a vinyl polymer, a cellulose polymer, a solvent, and the carbon nanotubes at room temperature, and a step of subjecting the mixture to high pressure 2 to 5 times using a diamond cell in a high-pressure disperser.

[0184] The above ball milling process may include a wet ball mill or a dry ball mill.

[0185] The above stirring may be performed at room temperature at 300 to 800 RPM for 2 to 4 hours. The dispersion medium may include water. The high pressure may be a pressure of 1,000 to 2,000 Mpa.

[0186] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

[0187]

[0188] Synthesis Example 1. Synthesis of vinyl dispersant.

[0189] 100 parts by weight of n-methyl-2-pyrrolidone was charged into a reaction vessel equipped with a gas inlet pipe, a thermometer, a condenser, and a stirrer, and the atmosphere was replaced with nitrogen gas. The inside of the reaction vessel was heated to 75°C, and a mixture prepared by mixing 3.0 parts by weight of styrene, 14.0 parts by weight of acrylic acid, 20 parts by weight of acrylomorpholine, and 2.5 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) was added dropwise over 3 hours to perform a polymerization reaction. After an additional polymerization reaction at 75°C for 1 hour, 0.5 parts of 2,2'-azobis(2,4-dimethylvaleronitrile) was added again, and the polymerization reaction was continued at 75°C for an additional hour to obtain a dispersant. At this time, the polystyrene-equivalent number average molecular weight measured using GPC (gel permeation chromatography) was 26,550 g / mol.

[0190]

[0191] Synthesis Example 2. Synthesis of vinyl dispersant

[0192] Synthesis was carried out in the same manner as in Synthesis Example 1, except that acrylic acid was replaced with vinyl sulfonic acid and 6 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) was used. At this time, the polystyrene-converted number-average molecular weight measured using GPC was 3.846 g / mol.

[0193]

[0194] Synthesis Example 3. Synthesis of vinyl dispersant

[0195] A dispersant was synthesized in the same manner as in Synthesis Example 1, except that 4.0 parts of vinyltoluene, 5.0 parts of vinylphosphonic acid, 25 parts by weight of acrylomorpholine, and 4 parts by weight of 2,2'-azobis(2,4-dimethylvaleronitrile) were used. At this time, the polystyrene-converted number-average molecular weight measured using GPC was 13,187 g / mol.

[0196]

[0197] Manufacturing Example 1. Manufacturing of conductive material slurry for secondary battery cathode

[0198] The particle size of carbon nanotubes was controlled using a wet ball mill. The wet ball mill used 3-pi zirconia balls and first dissolved 100 g of the synthesized dispersant in NMP solvent. Then, carbon nanotubes were added and the mixture was rotated at 550 RPM for 3 hours at room temperature to prepare a pre-dispersed solution of carbon nanotubes. The zirconia balls were removed from the prepared pre-dispersed solution and it was then subjected to a high-pressure disperser using a 200 μm diamond cell at a pressure of 1,000 MPa for 2 to 5 cycles to prepare a conductive material slurry for a secondary battery cathode.

[0199]

[0200] Manufacturing Example 2. Manufacturing of conductive slurry for secondary battery negative electrode

[0201] The particle size of carbon nanotubes was controlled using a wet ball mill. The wet ball mill was used, and 3-pi zirconia balls were used to first dissolve 100 g of the dispersant manufactured in the synthetic example in the amounts of each example and comparative example in water as a solvent, and then carbon nanotubes were additionally added and the mixture was rotated at 550 RPM for 3 hours at room temperature to prepare a pre-dispersion of carbon nanotubes. The zirconia balls were removed from the manufactured pre-dispersion, and this was processed 2 to 5 times in a high-pressure disperser using a 100 μm diamond cell at a pressure of 1,500 Mpa to prepare a conductive material slurry for a secondary battery anode.

[0202]

[0203] Manufacturing Example 3. Manufacturing of a standard anode

[0204] A mixture of PVDF as a binder and NMP as a solvent was prepared using a rotating-rotating mixer. The mixture was then mixed with a conductive material dispersion for a secondary battery cathode using a rotating-rotating mixer. The cathode active material (Umicore, NCM622) was then added and mixed using a rotating-rotating mixer to prepare a cathode slurry. The solid content of the cathode slurry was 60 wt%. The weight ratio of the cathode active material, conductive material, and binder in the cathode slurry was 94:3:3.

[0205] Next, a polarizing plate was formed using a blade on a 20 μm thick aluminum foil, which would become the current collector. Subsequently, the plate was dried in a vacuum oven at 120°C for 10 hours and rolled using a roll press to produce a standard anode having a composite layer density of 2.8 g / cc.

[0206]

[0207] Manufacturing Example 4. Fabrication of a standard cathode

[0208] A conductive dispersion for a secondary battery anode, carbon black, and a silicon-based active material, SiOx, were mixed using a rotating-rotating mixer. Thereafter, the mixture and artificial graphite were added and mixed using a rotating-rotating mixer. Thereafter, the mixture was mixed with water as a solvent and CMC as a thickener, and styrene butadiene as a binder was mixed using a rotating-rotating mixer to produce a cathode slurry. The weight ratio of the active material (artificial graphite:SiOx = 86.4:9.6), conductive material (carbon black:single-walled carbon nanotubes = 0.94:0.06 weight ratio), thickener, and binder in the anode slurry was 96:1:1.7:1.3.

[0209] Next, a 10 μm thick copper foil, which will become the current collector, was used to form an electrode plate using a blade. Subsequently, the electrode plate was dried in a vacuum oven at 120°C for 10 hours and rolled using a roll press to produce a standard cathode having a composite layer density of 1.6 g / cc.

[0210]

[0211] Experimental example

[0212] [Measurement of molecular weight of dispersant]

[0213] In order to measure the molecular weight of the vinyl dispersant manufactured according to the above synthetic example, the gel chromatography (GPC) method was used under the following conditions.

[0214] Device: HLC-8120GPC (Dososa)

[0215] Column: TSK-GELG4000HXL+ TSK-GELG2000HXL series connection

[0216] Column temperature: 40℃

[0217] Mobile phase solvent: tetrahydrofuran (THF)

[0218] Flow rate: 1.0 ml / min

[0219] Detector: RI detector

[0220] Measurement sample concentration: 0.6 wt% in THF

[0221] Calibration standard materials: TSK STANDARD POLYSTYRENE F-40, F-4, F-1, A-2500, A-500 (manufactured by Tosoh Corporation)

[0222]

[0223] [Physical properties, stability, and cell test evaluation of conductive dispersions for secondary battery cathodes]

[0224] The physical properties and stability of a conductive dispersion prepared by polymerizing a vinyl polymer, carbon nanotube, and solvent prepared according to the above Synthesis Examples 1 to 3 were evaluated.

[0225] The above-mentioned conductive dispersion was prepared by varying the conditions of carbon nanotube content, type and content of dispersant.

[0226]

[0227] 1) Measurement of particle size distribution of secondary battery conductive material dispersion

[0228] After allowing the secondary battery conductive material dispersion to stand in a constant temperature and humidity chamber at 25°C for more than 30 minutes, it was sufficiently stirred and diluted with 10% by weight of the secondary battery conductive material dispersion, NMP as a positive electrode solvent, and 90% by weight of H2O as a negative electrode solvent. The cumulative particle size D50 of the secondary battery conductive material dispersion was measured using a particle size analyzer (Microtrack, Model S3500). Dilution was performed so that the loading index value was in the range of 0.002 to 0.004.

[0229]

[0230] 2) Viscosity measurement of secondary battery conductive material dispersion

[0231] After allowing the secondary battery conductive material dispersion to stand in a constant temperature bath at 25°C for more than 30 minutes and stirring sufficiently, measurements were performed using a viscometer (Brookfield, Model DV2T). Measurements were performed using Spindle No. 4, adjusting the rotation speed RPM to match the conditions of 50 Torque.

[0232]

[0233] 3) Stability evaluation of secondary battery conductive material dispersion

[0234] After leaving the secondary battery conductive material dispersion in a 25℃ constant temperature and humidity chamber for 90 days, the dispersion was sufficiently stirred and then measured using a viscometer with Spindle No. 4 by adjusting the rotation speed RPM to match the condition of 50 Torque.

[0235]

[0236] 4) Cell test of secondary battery conductive material dispersion solution

[0237] A 2032 coin-cell type lithium-ion half-cell was fabricated. Both the standard positive and negative electrodes, each using lithium as a counter electrode, were manufactured in a glove box (Korea Engineering & Construction). The lithium-ion half-cell was placed in a 25°C constant-temperature and humidity chamber, and charge-discharge measurements were performed using a charge-discharge device (Won-A Tech, WBCS3000). After repeating 0.1C charge / 0.1C discharge three times, a 0.5C charge / 0.5C discharge cycle was performed to evaluate the charge-discharge characteristics.

[0238] Cell Test Evaluation Table

[0239] ○(Good): Cycle characteristics of 85% or more

[0240] △(Normal): Cycle characteristics are 75% or more and less than 85%

[0241] X (bad): cycle characteristics less than 75%

[0242] Table 1 below shows examples according to Manufacturing Example 3, and Table 2 shows comparative examples according to Manufacturing Example 3, showing a table evaluating particle size, viscosity, stability, and cell test of a conductive dispersion for a secondary battery cathode.

[0243]

[0244] Example CNT concentration (%) Dispersant type Dispersant content (%) Solvent particle size (D50: um) Viscosity (cPs) Stability (90 days) Cell test 1-15 Synthesis example 11 NMP 10.3 4 5 3 7.4 6 8 0.7 △ 1-25 Synthesis example 12 NMP 10.4 6 4.5 5 6 1.6 0 1-35 Synthesis example 14 NMP 10.3 7 3 9 0.9 4 8 2.3 0 1-45 Synthesis example 21 NMP 10.7 8 3 9 1.4 4 6.4 △ 1-55 Synthesis example 22 NMP 10.4 5 3 3 6.5 4 10.1 0 1-65 Synthesis example 24 NMP 10.3 1 2 9 5.2 3 5 1.9 0 1-75 Synthesis example 1 / PVP K30 * 0.5 / 0.5NMP10.67347.1560.2△1-85Synthesis example 1 / PVK K301 / 1NMP10.65292.4354.8△1-95Synthesis example 1 / PVK K302 / 2NMP10.54218.2310.5△1-105Synthesis example 2 / PVK K15 **0.5 / 0.5NMP10.31181.0270.5△1-115Synthesis example 2 / PVK K151 / 1NMP10.49158.7224.3△1-125Synthesis example 2 / PVK K152 / 2NMP10.23100.5162.0△1-1310Synthesis Example 31NMP10.48612.8722.2△1-1410Synthesis Example 32NMP10.42531.3632.5△1-1510Synthesis Example 34NMP10.49474.5560.3O1-1610Synthesis Example 21NMP10.87450.1533.7O1-1710Synthesis Example 22NMP10.62406.6452.8O1-1810Synthesis Example 24NMP10.58361.4420.5△1-1910Synthesis Example 1 / PVP K150.5 / 0.5NMP10.87368.4520.2△1-2010Synthesis Example 1 / PVP K151 / 1NMP10.69320.0482.3△1-2110Synthesis example 1 / PVP K152 / 2NMP10.87290.4365.8△1-2210Synthesis example 2 / PVK K300.5 / 0.5NMP10.21292.4350.1O

[0245] * PVP K30: Polyvinylpyrrolidone Mw 30,000~40,000

[0246] ** PVP K15: Polyvinylpyrrolidone Mw 30,000~40,000

[0247] Comparative Example CNT Concentration (%) Dispersant Type Dispersant Content (%) Solvent Particle Size (D50: um) Viscosity (cPs) Stability (90 days) Cell Test 2-15 PVP K30 * 1NMP10.44718.41293.2X2-25PVP K302NMP10.42616.5520.4X2-35PVK K304NMP10.27530.9621.4X2-45PVK K15 **1NMP10.78621.4866.7X2-55PVK K152NMP10.55593.5741.1X2-65PVK K154NMP10.51455.2680.5X2-710PVK K151NMP10.99968.21367.2X2-810PVK K152NMP11.10841.61210.8X2-910PVK K154NMP10.94693.31000.7X

[0248] * PVP K30: Polyvinylpyrrolidone Mw 30,000~40,000

[0249] ** PVP K15: Polyvinylpyrrolidone Mw 8,000~12,000

[0250]

[0251] [Physical Properties, Stability, and Cell Test Evaluation of Conductive Dispersion for Secondary Battery Negative Electrodes]

[0252] The physical properties and stability of conductive dispersions prepared by polymerizing vinyl polymers, carbon nanotubes, and solvents prepared according to Synthesis Examples 1 to 3 were evaluated. The evaluation was conducted in the same manner as the evaluation method for the anode dispersion.

[0253] The above-mentioned conductive dispersion was prepared by varying the conditions of carbon nanotube content, type and content of dispersant.

[0254] Table 3 below shows examples according to Manufacturing Example 4, and Table 4 shows comparative examples according to Manufacturing Example 4, showing a table evaluating particle size, viscosity, stability, and cell test of a conductive dispersion for a secondary battery negative electrode.

[0255] Example CNT concentration (%) Dispersant type Dispersant content (%) Solvent particle size (D50: um) Viscosity (cPs) Stability (90 days) Cell test 3-11 Synthesis example 11.0H2O 11.53 10 15.7 11 4 5.0 △ 3-21 Synthesis example 11.5H2O 11.72 8 58.3 9 58.3 △ 3-31 Synthesis example 12.0H2O 11.32 7 11.67 9 8.9 △ 3-43 Synthesis example 21.0H2O 11.88 135 1.9 16 9 4.7 △ 3-53 Synthesis example 21.5H2O 11.87 10 54.7 138 4.6 △ 3-63 Synthesis example 22.0H2O 11.66 9 42.9 12 23.0 △ 3-71 Synthesis example 1 / Cellulose polymer 1.5 / 1.0H2O11.54321.4394.0△3-81 Synthesis Example 1 / Cellulose polymer 1.5 / 2.0H2O11.52386.7454.5△3-91 Synthesis Example 1 / Cellulose polymer 1.5 / 3.0H2O11.44436.7492.6△3-101 Synthesis Example 2 / Smectide clay 1.5 / 0.1H2O10.92164.8218.0O3-111 Synthesis Example 2 / Smectide clay 1.5 / 0.2H2O11.20135.9163.2O3-121 Synthesis Example 2 / Smectide clay 1.5 / 0.3H2O11.19119.9134.6O3-133 Synthesis Example 3 / Cellulose Polymer 1.5 / 1.0H2O 11.60 70 5.177 9.8O 3-143 Synthesis Example 3 / Cellulose Polymer 1.5 / 2.0H2O 11.23 75 3.89 36.1O 3-153 Synthesis Example 3 / Cellulose Polymer 1.5 / 3.0H2O 11.21 84 1.510 52.7O 3-163 Synthesis Example 1 / Smectide Clay 1.5 / 0.1H2O 11.32 23 5.128 7.0 △ 3-173 Synthesis Example 1 / Smectide Clay 1.5 / 0.2H2O 11.38 209 522 3.6 △ 3-183 Synthesis Example 1 / Smectide Clay 1.5 / 0.3H2O 11.35 161.71 85.3 △

[0256] Cellulose polymer: Methyl cellulose (degree of esterification 0.8) Smectide viscosity: BYK Laponite RD

[0257]

[0258] Comparative Example CNT Concentration (%) Dispersant Type Dispersant Content (%) Solvent Particle Size (D50: um) Viscosity (cPs) Stability (90 days) Cell Test 4-11 Cellulose Polymer 0.5H2O 11.64 36 0.07 5 4.0 △ 4-21 Cellulose Polymer 1.5H2O 11.42 4 10.49 9 2.1 X 4-31 Cellulose Polymer 2.0H2O 11.40 5 2.2 31 10 0.0 X 4-41 Smectide Clay 0.1H2O 10.99 7 1.91 5 7.5 X 4-51 Smectide Clay 0.2H2O 10.93 25.26 9.1 △ 4-61 Smectide Clay 0.3H2O 10.88 <10 <10 △

[0259] Cellulose polymer: Methyl cellulose (degree of esterification 0.8) Smectide viscosity: BYK Laponite RD

Claims

1. A first repeating unit derived from polyvinyl containing morpholine as a functional group; A second repeating unit derived from polyvinyl containing an organic acid or an organic acid salt as a functional group; and A third repeating unit derived from polyvinyl containing an aromatic group as a functional group; Dispersant, a terpolymer polymer.

2. In paragraph 1, A dispersant characterized in that the first repeating unit is a vinyl monomer derived from (meth)acrylomorpholine.

3. In paragraph 1, A dispersant characterized in that the organic acid or organic acid salt of the second repeating unit is at least one selected from the group consisting of unsaturated sulfonic acid, unsaturated phosphoric acid, unsaturated carboxylic acid, and salts thereof.

4. In paragraph 3, The organic acid or organic acid salt of the second repeating unit is selected from the group consisting of sodium allyl sulfonate, sodium (methyl)allyl sulfonate, 2-(meth)acrylamide-2-methylpropane sulfonate, sodium styrene sulfonate, sodium 3-allyloxy-2-hydroxy-1-propanesulfonate, 2-methyl-2-(meth)acrylic acid-2-sulfonate ethyl ester, potassium 3-sulfopropyl (meth)acrylate, potassium 3-sulfopropyl (meth)acrylate, vinyl phosphonic acid, (1-phenylvinyl) phosphonic acid, allyl phosphonic acid, bis[2-(methacryloxy)ethyl] phosphoric acid, 2-(methacryloxy)ethyl-2-(trimethylamino)ethyl phosphate, 2-methyl-2-propenoic acid 2-(phosphonooxy)ethyl ester, A dispersant characterized by comprising at least one selected from the group consisting of (meth)acrylic acid, beta-carboxyethyl (meth)acrylate, 2-ethyl (meth)acrylic acid, α-acetoxy (meth)acrylic acid, butenoic acid, crotonic acid, maleic acid, itaconic acid, and fumaric acid.

5. In paragraph 1, A dispersant characterized in that the third repeating unit is a vinyl monomer containing a benzene ring.

6. In paragraph 1, A dispersant characterized in that the aromatic group of the third repeating unit is at least one selected from the group consisting of styrene, alpha styrene, vinyl toluene, 1-methoxy 4-vinylbenzene, 1-ethoxy 4-vinylbenzene, 1-(t-butyl)-4-vinylbenzene, 1,3,5-trimethyl-2-vinylbenzene, and 1,3,5-trichloro-2-vinylbenzene.

7. In paragraph 1, A dispersant characterized by the following chemical formula 1. [Chemical Formula 1] R1 to R3 in the above chemical formula 1 may each independently be hydrogen or methyl. The above R4 is an aliphatic or aromatic hydrocarbon group containing or not containing a heteroatom of 1 to 20 carbon atoms, linear, branched, or cyclic, with or without an unsaturated group, The above R5 is selected from at least one functional group consisting of sulfuric acid, phosphoric acid and carboxylic acid groups and salts of the sulfuric acid, phosphoric acid and carboxylic acid groups, The above R6 to R10 independently include at least one of a linear, branched, or cyclic aliphatic or aromatic hydrocarbon group containing or not containing hydrogen or an unsaturated group and containing or not containing a heteroatom having 1 to 20 carbon atoms, or a halogen element, The above l is 0.01 to 0.95, The above m is 0.04 to 0.60, The above n is 0.01 to 0.40, The sum of the above l, m and n is 1.

8. In paragraph 7, A dispersant characterized by the dispersant of the above chemical formula 1 being represented by the following chemical formulas 2 to 7. [Chemical Formula 2] [Chemical Formula 3] [Chemical Formula 4] [Chemical Formula 5] [Chemical Formula 6] [Chemical Formula 7] In the above chemical formulas 2 to 7, The above l is 0.01 to 0.95, The above m is 0.04 to 0.60, The above n is 0.01 to 0.40, The sum of the above l, m and n is 1.

9. In paragraph 8, A dispersant characterized in that the number average molecular weight (Mn) of the dispersant is 3,000 to 50,000 g / mol.

10. A conductive dispersion for a secondary battery comprising a dispersant, conductive material, and dispersion medium according to any one of claims 1 to 9.

11. In paragraph 10, A conductive dispersion for a secondary battery, characterized in that the dispersion further contains an amine compound.

12. In paragraph 11, A conductive dispersion for a secondary battery, characterized in that the above amine compound is at least one selected from the group consisting of methylamine, ethylamine, propylamine, butylamine, hexylamine, heptylamine, octylamine, dioctylamine, trioctylamine, t-octylamine, aminoethanol, aminopropanol, aminobutanol, aminopentanol, aminohexanol, dodecylamine, octadecylamine, tripropylamine, N,N-dimethylbenzylamine, 2-methoxyethylamine, and oleylamine.

13. In paragraph 10, A conductive material dispersion for a secondary battery, characterized in that the conductive material is at least one selected from the group consisting of carbon nanotubes, graphene oxide, graphene nanoplates, carbon black, and reduced graphene oxide.

14. In paragraph 10, A conductive material dispersion for a secondary battery, characterized in that the dispersion medium is at least one selected from the group consisting of n-methyl-2-pyrrolidone, dimethylformamide, dimethylsulfoxide, xylene, toluene, hexane, heptane, octane, cyclohexanone, cyclohexanone, ethyl acetate, propyl acetate, butyl acetate, methanol, ethanol, butanol, isopropyl alcohol, glycerol, isobutanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-methoxy propanol, tetrahydrofuran, formic acid, acrylonitrile, glycol ether, and water.

15. In paragraph 10, A conductive dispersion for a secondary battery, characterized in that the dispersion further comprises at least one of smectite clay and a cellulose-based compound.

16. In paragraph 15, A conductive dispersion for a secondary battery, characterized in that the cellulose compound is at least one selected from the group consisting of methylcellulose, ethylcellulose, hydroxyethylcellulose, benzylcellulose, tritylcellulose, cyanoethylcellulose, carboxymethylcellulose, carboxyethylcellulose, aminoethylcellulose, nitrocellulose, cellulose ether, and carboxymethylcellulose sodium salt.

17. In paragraph 10, A conductive dispersion for a secondary battery, characterized in that the content of the dispersant is included at 1 to 5 wt% based on the total content of the dispersion.

18. In paragraph 10, A conductive material dispersion for a secondary battery, characterized in that the content of the conductive material is included in an amount of 1 to 10 wt% relative to the total content of the dispersion.

19. A negative electrode slurry composition for a secondary battery comprising the dispersion of Article 10, a negative electrode active material, a thickener, a binder, and a solvent.

20. In paragraph 19, The above negative active material is SiO X A negative electrode slurry composition for a secondary battery, characterized in that it comprises (0≤X≤2) and a carbon-based active material.

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