KR20240078285A - Carbon black despersion, manufacturing method for same, slurry composition for electrode comprising same, eletrode comprising same and secondary battery comprising same - Google Patents

Abstract

This specification refers to carbon black; A first dispersant having an amide group; and a carbon black dispersion containing an acrylic second dispersant, a method for producing the same, an electrode slurry composition containing the same, an electrode containing the same, and a secondary battery containing the same.

Description

Carbon black dispersion, manufacturing method thereof, electrode slurry composition containing the same, electrode containing the same, and secondary battery containing the same }

This specification claims the benefit of the filing date of application No. 10-2022-0160685 filed with the Korean Intellectual Property Office on November 25, 2022, the contents of which are incorporated into this specification.

This specification relates to a carbon black dispersion, a method for producing the same, an electrode slurry composition containing the same, an electrode containing the same, and a secondary battery containing the same.

Secondary batteries are batteries that can be used repeatedly through the charging process, which is the reverse of the discharging process in which chemical energy is converted into electrical energy. A secondary battery consists of a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode and the negative electrode generally consist of an electrode current collector and an electrode active material layer formed on the electrode current collector. The electrode active material layer is manufactured by applying an electrode slurry composition containing an electrode active material, a conductive material, a binder, etc. on an electrode current collector, drying it, and then rolling it.

Carbon black is used as a material for coloring, light blocking, or conduction in various technical fields, and in order to meet the requirements for various applications, it has become important to finely disperse carbon black in a solvent.

Meanwhile, recently, there is a growing demand to install small, lightweight, yet high-capacity batteries in electronic devices. In addition, there continues to be a demand for improved performance of large secondary batteries for automotive use. In response to such demands, the development of secondary batteries is being actively conducted. Typically, the electrode of a secondary battery is formed by applying a slurry containing an electrode active material, a binder resin, and a conductive material to the surface of a current collector. At this time, carbon black may be added as a conductive material.

Carbon black has a strong cohesive force because it has a large specific surface area, and it is difficult to disperse uniformly in the slurry for forming electrodes. If the dispersibility of carbon black is insufficient, a uniform conductive network cannot be formed, so not only cannot a sufficient reduction in the internal resistance of the electrode be achieved, but also partial cohesion creates a resistance distribution inside the electrode, which reduces the current when the battery is used. Concentration may cause partial heat or deterioration. In addition, when charging and discharging are repeated, the interfacial adhesion between the current collector and the electrode layer, or between the active material and the carbon black, may deteriorate, leading to a decrease in battery performance. If the dispersibility of the carbon black is insufficient, the above-mentioned Deterioration of interfacial adhesion may become more severe.

To disperse carbon black, methods have been attempted using various additives, for example, dispersants such as surfactants or pigment dispersion resins. However, the method using a surfactant is advantageous for dispersion in aqueous systems, but is unsuitable for dispersion in organic solvents. Even when using a pigment dispersion resin, there is a problem that carbon black easily re-agglomerates or the aging stability is reduced. In addition, when manufacturing battery electrodes, if the amount of surfactant or pigment dispersion resin added is reduced, sufficient dispersibility cannot be obtained, and if the amount of surfactant or pigment dispersion resin added is increased to obtain sufficient dispersibility, the electrode active material As the content decreases, battery capacity may decrease.

Methods of introducing acidic functional groups to the surface of particles by oxidizing carbon black in the gas or liquid phase have been attempted, but gas-phase oxidation such as plasma or ozone treatment has problems such as low treatment efficiency and expensive treatment equipment, and liquid phase oxidation has problems such as low treatment efficiency and expensive treatment equipment. Because strong acids such as acetic acid and hydrogen peroxide are used in the treatment, there are problems with work safety, etc.

Additionally, in order to improve the dispersibility of carbon black, a method of adding vinyl pyrrolidone-based resin has been attempted. However, due to the hygroscopicity of the vinyl pyrrolidone resin, moisture is likely to be included in the electrode slurry or the electrode coating film, and the active material may deteriorate.

KR No. 10-2011-0118460

Toxicol. Res., 2015,4, 160-168

It relates to a carbon black dispersion with improved dispersibility of carbon black, a manufacturing method thereof, an electrode slurry composition containing the same, an electrode containing the same, and a secondary battery containing the same.

One embodiment of the present invention is carbon black; A first dispersant having an amide group; and a carbon black dispersion containing a second acrylic dispersant.

In addition, another embodiment of the present invention is carbon black; A first dispersant having an amide group; and mixing a second acrylic dispersant.

In addition, another embodiment of the present invention provides an electrode slurry composition including the carbon black dispersion described above, an electrode active material, and a binder.

Additionally, another embodiment of the present invention provides an electrode including an electrode active material layer formed by the above-described electrode slurry composition.

Additionally, another embodiment of the present invention provides a secondary battery including the above-described electrode.

The carbon black dispersion according to an exemplary embodiment of the present invention has a significantly lower viscosity and has the effect of improving the dispersibility of carbon black in the dispersion.

The carbon black dispersion according to an exemplary embodiment of the present invention has excellent coating properties and processability when used in electrode production.

Hereinafter, the present invention will be described in detail.

Carbon black dispersion according to an exemplary embodiment of the present invention refers to a dispersion containing carbon black. Specifically, it means that carbon black is dispersed in the dispersion liquid and does not aggregate with each other.

One embodiment of the present invention is carbon black; A first dispersant having an amide group; and a carbon black dispersion containing a second acrylic dispersant.

In one embodiment of the present invention, the two-dimensional carbon material dispersion may have a viscosity of 800 cPs or less at 25°C and a shear rate of 2.5 sec ^-1 . The viscosity may be 200 cPs or less, 150 cPs or less, 80 cPs or less, or 50 cPs or less. Considering the purpose of the present invention, the lower the viscosity, the better, so the lower limit is not particularly limited, but may be 1 cPs or more, 3 cPs or more, or 5 cPs or more. When the above viscosity range is satisfied, the carbon black in the carbon black dispersion does not aggregate with each other, and when used in electrode manufacturing, processability is improved.

In one embodiment of the present invention, the two-dimensional carbon material dispersion may have a viscosity of 300 cPs or less at 25°C and a shear rate of 15 sec ^-1 . The viscosity may be 200 cPs or less, 50 cPs or less, 40 cPs or less, or 30 cPs or less. Considering the purpose of the present invention, the lower the viscosity, the better, so the lower limit is not particularly limited, but may be 1 cPs or more, 3 cPs or more, or 5 cPs or more. When the above viscosity range is satisfied, the carbon black in the carbon black dispersion does not aggregate with each other, and when used in electrode manufacturing, processability is improved.

The viscosity of the carbon black dispersion can be measured by a method commonly used in the field to which this technology belongs. For example, it may be measured using Brookfield's DVNextCP Rheometer at a measurement temperature of 25°C and the shear rate described above. For more accurate measurement, the prepared carbon black dispersion can be stored at 25°C for one week and then measured.

In one embodiment of the present invention, the BET specific surface area of the carbon black may be 30 m ² /g to 1,300 m ² /g. It may be preferably 30 m ² /g to 900 m ² /g, more preferably 30 m ² /g to 500 m ² /g, and even more preferably 30 m ² /g to 300 m ² /g. Within the above numerical range, the electrical conductivity of carbon black is excellent and agglomeration phenomenon can be controlled.

In general, carbon black is prone to agglomeration due to van der Waals forces between each other, and a dispersion technology that can well disperse the agglomerated carbon black when dispersed in a solvent is required. When carbon black agglomerates, there is a problem that the viscosity of the dispersion increases. The high viscosity of the dispersion can increase the viscosity of the slurry when manufacturing electrodes for secondary batteries, creating non-uniform dispersion between the anode material and binder, which are electrode materials.

The present inventors developed a dispersion that improves dispersibility and enables economical electrode production even when using carbon black.

In one embodiment of the present invention, the carbon black dispersion includes a first dispersant having an amide group; and an acrylic second dispersant. The first dispersant having an amide group is effective in dispersing carbon black, and the acrylic group of the second acrylic-based dispersant provides high water absorption and can effectively reduce the viscosity of the dispersion.

In one embodiment of the present invention, the first dispersant has an amide group, so that it can form a hydrogen bond with the hydroxyl group or carboxyl group of the second dispersant, which will be described later.

In one embodiment of the present invention, the first dispersant is polyvinylpyrrolidone, polyester amide, polycarboxylic amide, polyamido amine, cylindrical It may be thioamido amine, water soluble nylon compound, or a combination thereof. By having an amide group, the first dispersant can further improve viscosity and suppress changes in viscosity over time.

In one embodiment of the present invention, the weight average molecular weight of the first dispersant may be 1,000 g/mol to 100,000 g/mol. Preferably, it may be 2,000 g/mol to 80,000 g/mol, 2,000 g/mol to 30,000 g/mol, or 2,000 g/mol to 15,000 g/mol. If the weight average molecular weight of the first dispersant is less than 1,000 g/mol, the carbon black dispersion performance may be poor, and a problem may occur in which the first dispersant is eluted during electrode manufacturing, and if it exceeds 100,000 g/mol, the carbon black may be dissolved. Since the viscosity of the dispersion may increase and coatability and processability may deteriorate, it is preferable to adjust it to the above range.

In one embodiment of the present invention, the second dispersant is a hydroxyl group; Alternatively, it may contain a carboxyl group. The second dispersant is a hydroxyl group; Alternatively, by having a carboxyl group, a hydrogen bond can be formed with the amide group of the first dispersant described above.

In one embodiment of the present invention, the second dispersant may be a polyacrylic acid compound. The polyacrylic acid compound refers to an acrylic acid compound containing two or more acidic hydrogen atoms.

In one embodiment of the present invention, the polyacrylic acid compound may be polyacrylic acid (PAA) or a polyacrylic acid derivative. The polyacrylic acid derivative may be polyacrylic acid-maleic acid copolymer (PAAMA).

In one embodiment of the present invention, the weight ratio of the first dispersant and the second dispersant may be 1:10 to 10:1. Preferably, it may be 1:5 to 5:1, or 1:3 to 3:1. When the above range is satisfied, the dispersion effect of carbon black is improved and the viscosity of the dispersion liquid can be maintained low.

In one embodiment of the present invention, the content of the first dispersant may be 0.01 wt% to 10 wt% based on the total weight of the dispersion. Preferably, it may be 0.01 wt% to 5 wt%, or 0.1 wt% to 3 wt%.

In one embodiment of the present invention, the content of the second dispersant may be 0.01 wt% to 10 wt% based on the total weight of the dispersion. Preferably, it may be 0.01 wt% to 5 wt%, or 0.1 wt% to 3 wt%.

In one embodiment of the present invention, the carven black dispersion may include an alkali metal element. As the carbon black dispersion of the present invention contains the alkali metal element, the dispersibility of the material contained in the dispersion can be improved. Specifically, the first and second dispersants included in the dispersion may form a complex with each other, but such complexes have a problem of increasing the viscosity of the dispersion due to their low solubility in solvents such as water. However, the above problem can be solved by the alkali metal contained in the carbon black dispersion of the present invention breaking up the complex. The form of the alkali metal is not particularly limited, but may exist in the form of an alkali metal salt containing an alkali metal.

In one embodiment of the present invention, the carbon black dispersion is characterized in that it contains an alkali metal salt. The form of the alkali metal is not particularly limited, but may exist in the form of an alkali metal salt containing an alkali metal.

Although the first and second dispersants form hydrogen bonds and can contribute to reducing the viscosity of the dispersion, there is a problem in that the hydrogen bonds are too strong and insoluble substances or complexes are formed. In this case, there are many restrictions on the selection of the dispersant, such as having to adjust the contents of the first and second dispersants or using only specific types of first and/or second dispersants. However, when the carbon black dispersion contains an alkali metal element, the alkali metal element suppresses the phenomenon of agglomeration of the first and second dispersants described above, thereby keeping the viscosity of the dispersion low. The improvement in the agglomeration phenomenon can be confirmed by preparing a carbon black dispersion containing the above materials, leaving it for a certain period of time, and visually observing whether there is aggregation.

In one embodiment of the present invention, the alkali metal salt is one selected from the group consisting of KOH, NaOH, LiOH, KOHH ₂ O, NaOHH ₂ O, LiOHH ₂ O, K ₂ CO ₃ , Na ₂ CO ₃ and LiCO ₃ It may include more.

In one embodiment of the present invention, the content of the alkali metal element may be 1 ppm or more and 300 ppm or less, based on the entire carbon black dispersion. Preferably, it may be 5 ppm or more and 200 ppm or less, or 5 ppm or more and 150 ppm or less.

In one embodiment of the present invention, the content of the alkali metal element can be adjusted in consideration of the type and content of the first dispersant.

In one embodiment of the present invention, the first dispersant includes a polyvinylpyrrolidone-based resin, and the molar ratio of the alkali metal salt is based on 100 mol of vinylpyrrolidone units included in the polyvinylpyrrolidone-based resin. , may be 60 mol or less. Preferably, it may be 30 mol or less, or 25 mol or less. The lower limit of the content is not particularly limited, but may be 0.1 mol or more, 0.2 mol or more, or 0.5 mol or more. When the above range is satisfied, the viscosity of the carbon black dispersion can be lowered.

The molar ratio of the alkali metal salt can be calculated using the molecular weight of the alkali metal salt and vinylidone unit and the weight percent of the alkali metal salt and polyvinylidone. Specifically, it can be calculated through Equation 1 below.

[Equation 1]

Molar ratio of alkali metal salt = {(% by weight of alkali metal salt)/(molecular weight of alkali metal salt)}/{(% by weight of polyvinylidone)/(molecular weight of vinylidone monomer)}*100

For example, based on the total weight of the dispersion, the contents of polyvinylpyrrolidone and alkali metal salt (LiOH) are 0.9 wt% and 0.003 wt%, respectively, the molecular weight of alkali metal salt (LiOH) is 24 g/mol, and vinylidone If the molecular weight of the monomer is 111.14 g/mol, the molar ratio of the alkali metal salt is calculated as 1.5 mol based on 100 mol of vinylpyrrolidone monomer [1.5={(0.003)/(24)}/{(0.9)/(111.14 )}*100]

The vinylpyrrolidone unit refers to a unit composed of a 5-membered lactam linked to a vinyl group, and refers to a unit constituting the polyvinylpyrrolidone-based resin. Specifically, it may be a monomer represented by the formula 2 among polyvinylpyrrolidone represented by the formula 1 below.

[Formula 1]

[Formula 2]

In one embodiment of the present invention, various types of carbon black, such as commercially available furnace black, channel black, thermal black, acetylene black, and Ketjen black, can be used as carbon black. Additionally, hollow carbon black, etc. can also be used.

In one embodiment of the present invention, the diameter of the carbon black unit may be 1 nm or more and 200 nm or less. Preferably, it may be 1 nm or more and 150 nm or less, or 1 nm or more and 100 nm or less. Within the above numerical range, the dispersibility of carbon black can be improved and resistance from increasing when applied to an electrode can be prevented.

In one embodiment of the present invention, the length of the carbon black unit may be 0.1 μm or more and 200 μm or less. Preferably, it may be 0.1 μm or more and 150 μm or less, or 0.5 μm or more and 100 μm or less. Within the above numerical range, the dispersibility of carbon black can be improved and resistance from increasing when applied to an electrode can be prevented.

In one embodiment of the present invention, the aspect ratio (length/diameter) of the carbon black may be 5 to 50,000 or 10 to 15,000. Within the above numerical range, the dispersibility of carbon black can be improved and resistance from increasing when applied to an electrode can be prevented.

In one embodiment of the present invention, the average particle diameter (D50) of the carbon black may be 0.1 ㎛ to 20 ㎛. Preferably, it may be 0.1 ㎛ to 15 ㎛, 0.1 ㎛ to 10 ㎛, or 0.1 ㎛ to 5 ㎛. The average particle size (D50) refers to the particle size corresponding to 50% of the cumulative number in the particle size distribution curve of carbon black. The average particle diameter (D50) can be measured using, for example, a laser diffraction method. Within the above range, carbon black does not aggregate with each other and dispersibility can be improved.

In one embodiment of the present invention, the content of carbon black may be 0.01 wt% to 20 wt% based on the total weight of the carbon black dispersion. Preferably it may be 1 wt% to 8 wt%. Within the above numerical range, the loading amount is reduced during electrode manufacturing, thereby preventing an increase in process costs, and preventing problems such as binder migration occurring during electrode drying, reducing adhesion, or increasing the viscosity of the carbon black dispersion. can do.

In one embodiment of the present invention, the value expressed by Equation 2 below of the carbon black dispersion may be 1 to 10. Preferably, it may be 1 to 6, or 1 to 4. The value expressed in Equation 2 below is the shear fluidization index of the dispersion, which means the ratio of viscosity measured at different shear rates. When the above range is satisfied, uniform mixing is possible when manufacturing electrodes by preventing the viscosity from becoming too high in a standing state and reducing fluidity. Additionally, storage stability can be improved by preventing sedimentation of carbon black particles.

[Equation 2]

Shear Thinning index (STI) = V _low /V _high

In equation 2 above,

V _low is the viscosity of the dispersion measured at 25°C and a shear rate of 2.5 sec ^-1 ,

V _high is the viscosity of the dispersion measured at 25°C and a shear rate of 15 sec ^-1 .

In one embodiment of the present invention, the value calculated from Equation 3 below of the carbon black dispersion may be 1 to 10. Preferably, it may be 2 to 8 or 3 to 6. The value calculated by Equation 3 below represents the relationship between the shear fluidization index (STI) characteristics of the above-described dispersion and the average particle size of the carbon black contained in the dispersion. In general, if the carbon black particle size (D50) is too small, the shear fluidization index (STI) of the dispersion tends to increase as the carbon black agglomerates with each other. In addition, if the carbon black particle size (D50) is too large, the carbon black is not sufficiently dispersed, so the carbon black forms a network structure, and the overall viscosity and shear fluidization index (STI) of the dispersion tend to increase.

However, the carbon black dispersion according to an exemplary embodiment of the present invention has the effect of improving the viscosity stability over time of the entire dispersion even if the particle size of the carbon black is small by adjusting the value calculated by Equation 3 below to the numerical range below.

[Equation 3]

In equation 3 above,

STI is the shear thinning index (STI) of the dispersion,

D50 is the average particle size (D50) of the carbon black.

In one embodiment of the present invention, the carbon black dispersion may further include a solvent. The solvent is used to pre-disperse carbon black and supply it as a carbon black dispersion to prevent agglomeration when directly mixed with an electrode active material and used as an electrode slurry composition.

In one embodiment of the present invention, the solvent may be an aqueous solvent. For example, the aqueous solvent may be water. In this case, it is easy to control the viscosity of the dispersion.

In one embodiment of the present invention, the pH of the carbon black dispersion may be 3 to 10. Preferably, the pH may be 4 to 9 or 5 to 8. Within the above numerical range, the phenomenon of aggregation of the first and second dispersants described above can be further suppressed. Specifically, if the pH of the dispersion is outside the above numerical range, the strength of the surface charges of the first and second dispersants may become too strong or too weak, and hydrogen bonds may become too strong, resulting in significant aggregation. At this time, by adjusting the pH of the dispersion to the above numerical range, the phenomenon of agglomeration of the first and second dispersants can be further suppressed. The pH can be measured at 25°C.

One embodiment of the present invention is carbon black; A first dispersant having an amide group; and mixing a second acrylic dispersant.

In one embodiment of the present invention, carbon black; A first dispersant having an amide group; And the step of mixing the second acrylic dispersant may be performed under temperature conditions where physical properties do not change. For example, it may be carried out at a temperature of 50°C or lower, more specifically between 5°C and 50°C.

In one embodiment of the present invention, the step of dispersing the carbon black is performed using a ball mill, a bead mill, a disc mill or a basket mill, or a high pressure homogenizer. It may be performed by a method such as a pressure homogenizer, and more specifically, it may be performed by a milling method using a disk mill or a high pressure homogenizer.

When milling by the disk mill, the size of the bead can be appropriately determined depending on the type and amount of carbon nanotubes and the type of dispersant. Specifically, the diameter of the bead is 0.1 mm to 5 mm, more specifically 0.5 mm. It may be from mm to 4 mm. Additionally, the bead milling process may be performed at a speed of 2,000 rpm to 10,000 rpm, and more specifically, may be performed at a speed of 5,000 rpm to 9,000 rpm.

Milling using the disk mill may be performed at a speed of 2,000 rpm to 10,000 rpm, and more specifically, may be performed at a speed of 2,000 rpm to 5,000 rpm.

Milling using the disk mill may be performed under pressure conditions of 500 bar to 3,000 bar, and more specifically, may be performed under pressure conditions of 1,000 bar to 2,000 bar.

In one embodiment of the present invention, the step of dispersing the carbon black may be performed for 10 minutes to 120 minutes, more specifically, 20 minutes to 90 minutes, so that the carbon black can be sufficiently dispersed.

One embodiment of the present invention provides an electrode slurry composition including the carbon black dispersion described above, an electrode active material, and a binder.

In one embodiment of the present invention, the electrode active material includes a silicon-based electrode active material. The silicon-based electrode active material is metallic silicon (Si), silicon oxide (SiOx, where 0<x<2) silicon carbide (SiC), and Si-Y alloy (where Y is an alkali metal, alkaline earth metal, group 13 element, group 14 It is an element selected from the group consisting of elements, transition metals, rare earth elements, and combinations thereof, but may include one or more types selected from the group consisting of Si. The element Y includes Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, It may be selected from the group consisting of Se, Te, Po, and combinations thereof.

In one embodiment of the present invention, the silicon-based electrode active material exhibits higher capacity characteristics compared to the carbon-based electrode active material, so when the silicon-based electrode active material is additionally included, better capacity characteristics can be obtained. However, silicon-based electrode active materials have a large volume change during charging and discharging, so when charging and discharging are repeated, battery characteristics rapidly deteriorate and cycle characteristics are not sufficient, which has led to difficulties in commercialization. However, when carbon black is used as a conductive material as in the present invention, cycle characteristics can be improved when applying a silicon-based electrode active material. Therefore, by using the electrode slurry composition of the present invention containing the carbon black dispersion of the present invention and the silicon-based electrode active material, a secondary battery with excellent capacity characteristics and cycle characteristics can be implemented.

In one embodiment of the present invention, the electrode active material may further include other types of electrode active materials along with the silicon-based electrode active material. Examples of the other types of electrode active materials include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; Metallic compounds that can be alloyed with lithium, such as Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; Metal oxides that can dope and undope lithium, such as SnO2, vanadium oxide, and lithium vanadium oxide; Alternatively, a composite containing the above-described metallic compound and a carbonaceous material, such as a Sn-C composite, may be used, and among these, a carbonaceous material is particularly preferable.

In one embodiment of the present invention, the total amount of the electrode active material, which is a combination of the silicon-based electrode active material and other types of electrode active materials, is 70 to 99 wt%, preferably 80 to 99 wt%, based on the total solid content in the electrode slurry composition. It may be 98wt%. When the content of the electrode active material satisfies the above range, excellent capacity characteristics can be achieved.

In one embodiment of the present invention, the binder is used to secure adhesion between active materials or between an active material and a current collector. General binders used in the relevant technical field may be used, and their types are not particularly limited. . Examples of the binder include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, and carboxylic acid. Methylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated -EPDM, styrene-butadiene rubber (SBR), fluorine rubber, or various copolymers thereof may be used, and one of these may be used alone or a mixture of two or more may be used.

In one embodiment of the present invention, the binder may be included in an amount of 5 wt% or less, preferably 1 to 3 wt%, based on the total solid content in the electrode slurry composition. When the binder content satisfies the above range, excellent electrode adhesion can be achieved while minimizing increase in electrode resistance.

In one embodiment of the present invention, the electrode slurry composition may further include a solvent, if necessary, for viscosity control, etc. At this time, the solvent may be water, an organic solvent, or a mixture thereof. Examples of the organic solvent include amide-based polar organic solvents such as dimethylformamide (DMF), diethyl formamide, dimethyl acetamide (DMAc), and N-methyl pyrrolidone (NMP); Methanol, ethanol, 1-propanol, 2-propanol (isopropyl alcohol), 1-butanol (n-butanol), 2-methyl-1-propanol (isobutanol), 2-butanol (sec-butanol), 1-methyl Alcohols such as -2-propanol (tert-butanol), pentanol, hexanol, heptanol, or octanol; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, or hexylene glycol; polyhydric alcohols such as glycerin, trimethylolpropane, pentaerythritol, or sorbitol; Ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetra ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol mono ethyl ether, tetra ethylene glycol Glycol ethers such as mono ethyl ether, ethylene glycol mono butyl ether, diethylene glycol mono butyl ether, triethylene glycol mono butyl ether, or tetra ethylene glycol mono butyl ether; Ketones such as acetone, methyl ethyl ketone, methyl propyl ketone, or cyclopentanone; Examples include esters such as ethyl acetate, γ-butyl lactone, and ε-propiolactone, and any one or a mixture of two or more of these may be used, but is not limited thereto.

In one embodiment of the present invention, the electrode slurry composition may further include additives such as viscosity modifiers, fillers, etc., if necessary.

One embodiment of the present invention provides an electrode including an electrode active material layer formed by the above-described electrode slurry composition. Specifically, the electrode can be manufactured by applying the electrode slurry composition of the present invention described above and drying it to form an electrode active material layer. More specifically, the electrode active material layer is formed by applying an electrode slurry composition on an electrode current collector and then drying it, or by applying the electrode slurry composition on a separate support and then peeling it off from this support to form a film obtained as an electrode collector. It can be formed through a method of lamination on the entire surface. If necessary, after forming the electrode active material layer through the above method, a rolling process may be additionally performed. At this time, drying and rolling may be performed under appropriate conditions considering the physical properties of the electrode to be finally manufactured, and are not particularly limited.

In one embodiment of the present invention, the electrode current collector is not particularly limited as long as it is a conductive material without causing chemical changes in the battery, for example, copper, stainless steel, aluminum, nickel, titanium, and alloys thereof. , their surfaces may be surface treated with carbon, nickel, titanium, silver, etc., or calcined carbon may be used.

In one embodiment of the present invention, the electrode current collector may typically have a thickness of 3㎛ to 500㎛, and fine irregularities may be formed on the surface of the current collector to strengthen the bonding force of the electrode active material. Additionally, the electrode current collector may be used in various forms, such as films, sheets, foils, nets, porous materials, foams, and non-woven fabrics.

In one embodiment of the present invention, the electrode may be a cathode.

One embodiment of the present invention provides a secondary battery including the above-described electrode.

One embodiment of the present invention includes an anode; cathode; and a separator and an electrolyte provided between the anode and the cathode, wherein at least one of the anode and the cathode is the electrode described above.

In one embodiment of the present invention, the secondary battery may be a lithium secondary battery.

In one embodiment of the present invention, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move, and can be used without particular restrictions as long as it is normally used as a separator in secondary batteries. Specifically, the separator is a porous polymer film, for example, a porous film made of polyolefin-based polymers such as ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate copolymer. A polymer film or a laminated structure of two or more layers thereof may be used. In addition, conventional porous non-woven fabrics, for example, non-woven fabrics made of high melting point glass fibers, polyethylene terephthalate fibers, etc., may be used. In addition, a coated separator containing ceramic components or polymer materials may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

In one embodiment of the present invention, the electrolyte includes an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, and a molten inorganic electrolyte that can be used when manufacturing a secondary battery. It is not limited to.

Hereinafter, the present invention will be described in more detail through examples.

<Method for measuring physical properties>

The physical properties of the dispersions of Examples and Comparative Examples were measured using the method below.

Viscosity measurement

Brookfield's DVNextCP Rheometer was used, and measurements were made at 25°C by changing the shear rate to 2.5 sec ^-1 and 15 sec ^-1 , respectively.

Average particle size measurement

A laser diffraction method was used, and a commercially available laser diffraction particle size measurement device (Malvern Mastersizer3000) was used. The average particle size (D50) based on 50% of the particle size distribution was calculated using the measuring device. Meanwhile, D10 and D90 mean particle sizes at 10% and 90% particle size distribution, respectively.

Solids measurement

It was measured using OHAUS' MB95 moisture analyzer. Place about 3g of sample on an aluminum sample plate, measure the starting weight, heat to 150℃ and measure the weight. If the weight changes by less than 1mg in 60 seconds at 150℃, set it as dry weight and measure the weight as shown below. The solid content is calculated by the formula.

%DC (solid content) = dry weight/starting weight x 100%

Shear Thinning index (STI) measurement

It was calculated according to Equation 2 below.

[Equation 2]

Shear Thinning index (STI) = V _low /V _high

In Equation 2, V _low is the viscosity of the dispersion measured at 25°C and a shear rate of 2.5 sec ^-1 , and V _high is measured at 25°C and a shear rate of 15 sec ^-1 It is the viscosity of a dispersion.

Calculate the value calculated by Equation 3

The physical property values expressed in Equation 3 below were calculated. At this time, STI is the shear thinning index (STI) of the dispersion, and D50 is the average particle diameter (D50) of the carbon nanotubes.

[Equation 3]

<Preparation of dispersion>

Example 1

Carbon black (CB1: Super P, manufactured by Imerys) 15wt%, polyvinyl pyrrolidone (K17, Sigma-Aldrich) 1.125wt% as the first dispersant, polyacrylic acid (PAA) 1.125wt% as the second dispersant, solvent 1kg of carbon black dispersion was prepared by mixing water.

At this time, the molar ratio of the alkali metal salt was 7.7 mol based on 100 mol of vinylpyrrolidone unit, according to Equation 1 below.

[Equation 1]

Molar ratio of alkali metal salt = {(% by weight of alkali metal salt)/(molecular weight of alkali metal salt)}/{(% by weight of polyvinylidone)/(molecular weight of vinylidone monomer)}*100

Examples and Comparative Examples

For the remaining examples and comparative examples, dispersions were prepared by changing the weight and type of each material as shown in Tables 1 and 2 below, and the physical properties were tested.

division Example One 2 3 4 5 6 7 carbon black type CB1 CB1 CB1 CB1 CB1 CB1 CB1 Content (wt%) 15 15 15 15 15 15 15 Specific surface area (m ² /g) 62 62 62 62 62 62 62 first dispersant Polyvinylidone-based resin content (wt%) 1.125 1.125 1.125 1.125 1.125 0.75 0.75 Types of polyvinylidone resins K17 K17 K17 K17 K17 K17 K17 secondary dispersant Content (wt%) 1.125 1.125 1.125 1.125 1.125 0.75 0.75 type PAA PAA PAA PAA PAA PAA PAA - Content ratio of polyvinylidone resin and tannic acid compound 1:1 1:1 1:1 1:1 1:1 1:1 1:1 alkali
metal salt LiOH weight 0.019 - - 0.008 0.038 0.038 0.038 NaOH weight - 0.031 - - - - - KOH weight - - 0.044 - - - - Alkali metal element content in dispersion (ppm) 54 180 306 22 108 108 108 Number of moles of alkali salt per 100 mol of N-vinylpyrrolidone 7.7 7.7 7.7 3.1 15.5 23.2 23.2 Properties Viscosity (cps@2.5/s) 25.4 29.7 31.2 27.2 34.1 26.8 8.5 Viscosity (cps@15/s) 9.8 12.1 20.6 18.2 18 19 4.9 D50(㎛) 0.45 0.51 0.44 0.46 0.55 0.47 0.52 Solid content (%) 16.5 16.5 16.5 16.5 16.5 16.5 16.5 Equation 2 2.59 2.45 1.51 1.49 1.89 1.41 1.73 Equation 3 5.76 4.81 3.44 3.25 3.44 3.00 3.34

division Example Comparative example 8 9 One 2 3 4 carbon black type CB1 CB1 CB1 CB1 CB1 CB1 Content (wt%) 15 15 15 15 15 15 Specific surface area (m ² /g) 62 62 62 62 62 62 first dispersant Polyvinylidone-based resin content (wt%) 0.75 1.125 One Not included 1.125 1.125 Types of polyvinylidone resins K15 K17 K17 Not included K17 K17 secondary dispersant Content (wt%) 0.75 0.375 Not included One 0.375 0.375 type PAA PAAMA PAA PAA PAA PAAMA - Ratio of first and second dispersants 1:l 3:1 - - - - alkali
metal salt LiOH weight 0.038 0.019 - - - - NaOH weight - - - - - - KOH weight - - - - - - Alkali metal element content in dispersion (ppm) 0.038 0.019 - - - - Number of moles of alkali salt per 100 mol of N-vinylpyrrolidone 23.2 7.7 - - - - Properties Viscosity (cps@2.5/s) 35.9 36 94.1 818 89.3 170 Viscosity (cps@15/s) 12.6 15 48.2 375 40.4 53.3 D50(㎛) 0.49 0.53 1.2 1.5 1.31 1.33 Solid content (%) 16.5 16.5 16.0 16.0 16.5 16.5 Equation 2 2.85 2.40 1.95 2.18 2.21 3.19 Equation 3 5.81 4.53 1.63 1.45 1.69 2.40

In Tables 1 and 2 above, K15 and K17 refer to Aldrich products.

In Tables 1 and 2 above, CB1 is Super P from Imerys.

In Tables 1 and 2, PAA is polyacrylic acid, and PAAMA is polyacrylic acid-maleic acid copolymer (PAAMA).

From the above results, it was confirmed that the viscosity of the example dispersion was maintained low at 25°C and a shear rate of 15 sec ^-1 .

From the above results, it was confirmed that the viscosity increased when the dispersion did not contain the first or second dispersant (Comparative Examples 1 and 2).

In addition, even if the dispersion contained the first and second dispersants, it was confirmed that the viscosity increased when it did not contain an alkali metal salt (Comparative Examples 3 and 4).

Claims (15)

carbon black;
A first dispersant having an amide group; and
Carbon black dispersion containing an acrylic second dispersant. In claim 1,
The first dispersant is polyvinylpyrrolidone, polyester amide, polycarboxylic amide, polyamido amine, thioamido amine, water-soluble A carbon black dispersion that is a nylon compound (water soluble Nylon) or a combination thereof. In claim 1,
The second dispersant is a hydroxyl group; Or a carbon black dispersion containing a carboxyl group. In claim 1,
A carbon black dispersion wherein the weight ratio of the first dispersant and the second dispersant is 1:10 to 10:1. In claim 1,
A carbon black dispersion containing an alkali metal element. In claim 1,
A carbon black dispersion containing an alkali metal salt. In claim 1,
The alkali metal salt is a carbon black dispersion containing at least one selected from the group consisting of KOH, NaOH, LiOH, KOHH ₂ O, NaOHH ₂ O, LiOHH ₂ O, K ₂ CO ₃ , Na ₂ CO ₃ and LiCO ₃ . In claim 6,
The first dispersant includes a polyvinylpyrrolidone-based resin,
A carbon black dispersion wherein the molar ratio of the alkali metal salt is 60 mol or less based on 100 mol of vinyl pyrrolidone units included in the polyvinyl pyrrolidone-based resin. In claim 1,
A carbon black dispersion wherein the carbon black has an average particle diameter (D50) of 0.1 ㎛ to 20 ㎛. In claim 1,
A carbon black dispersion wherein the content of carbon black is 0.01 wt% to 20 wt% based on the total weight of the carbon black dispersion. carbon black; A first dispersant having an amide group; And mixing a second acrylic dispersant.
A method for producing a carbon black dispersion according to any one of claims 1 to 10. An electrode slurry composition comprising the carbon black dispersion according to any one of claims 1 to 10, an electrode active material, and a binder. An electrode comprising an electrode active material layer formed by the electrode slurry composition according to claim 12. In claim 13,
The electrode is a cathode. A secondary battery comprising the electrode according to claim 14.