Carbon nanotube dispersion and preparation method thereof

Abstract

The present invention relates to a carbon nanotube dispersion containing carbon nanotubes, a first dispersant containing a nitrogen atom, a second dispersant containing a compound represented by Formula 1, and a solvent, and a method for preparing the same. The content of the compound represented by Formula 1 is as defined in the specification.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0099772, filed on July 31, 2023, and Korean Patent Application No. 10-2024-0100273, filed on July 29, 2024, which are incorporated herein by reference in their entirety as a part of this specification.

[0002] The invention relates to a carbon nanotube dispersion and a preparation method thereof. Background Art

[0003] With the technological development and increasing demand for mobile devices, the demand for secondary batteries as energy sources is rapidly increasing. Among these secondary batteries, lithium secondary batteries with high energy density and voltage, long cycle life and low self-discharge rate have been commercialized and widely used. In addition, methods for manufacturing electrodes with higher energy density per unit volume as electrodes for high-capacity lithium secondary batteries by improving electrode density are being actively studied.

[0004] High-density electrodes are typically formed by molding electrode active material particles ranging in size from several to tens of μm using high-pressure pressing. However, during the molding process, the particles may deform and the spaces between the particles may decrease, which can easily reduce electrolyte solution permeability.

[0005] To address these issues, conductive materials with excellent conductivity and strength are used during electrode manufacturing. These materials are positioned between the electrode active materials and maintain micropores between the active material particles even during the molding process, allowing for easy penetration of the electrolyte solution. They also exhibit excellent conductivity, thereby reducing resistance within the electrode. Among these conductive materials, the use of carbon nanotubes, a fiber-type carbon-based conductive material that can further reduce electrode resistance by forming conductive pathways within the electrode, is increasing.

[0006] Carbon nanotubes (CNTs), a type of microcarbon fiber, are tubular carbon fibers with a diameter of 1 μm or less. Due to their high electrical conductivity, tensile strength, and heat resistance, resulting from their unique structure, they are expected to be used and commercialized in various fields. However, CNTs have the following problems: they have low dispersibility and agglomerate due to the strong van der Waals attraction between them caused by their high specific surface area.

[0007] To address these issues, methods have been proposed for dispersing carbon nanotubes in a dispersion medium using mechanical dispersion treatments, such as ultrasonic treatment. However, mechanical dispersion treatments have the problem that the carbon nanotubes aggregate once ultrasonic irradiation ends, or aggregate again over time after dispersion.

[0008] Therefore, there is a need to develop a method for preparing a carbon nanotube dispersion that can improve the dispersibility of carbon nanotubes while having low viscosity and suppressing the increase in viscosity over time.

[0009] [Prior art literature]

[0010] [Patent Document]

[0011] (Patent Document 1) U.S. Patent Publication No. 2020-0309771 (October 1, 2020) Summary of the Invention

[0012] Technical issues

[0013] An object of the present invention is to provide a carbon nanotube dispersion comprising carbon nanotubes, a first dispersant containing nitrogen atoms, a second dispersant containing a compound represented by the following Formula 1, and a solvent, which has excellent dispersibility and, therefore, has a low dispersion viscosity and a small particle size of dispersed particles, and has a small change in viscosity over time.

[0014] [Formula 1]

[0015]

[0016] in,

[0017] Ar1 and Ar6 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 aryl group,

[0018] Ar2 to Ar5 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 arylene group, and

[0019] L1 is an amino linkage, an ether linkage, a thiol linkage, a hydrazine linkage, a sulfinate linkage, a sulfonate linkage, a sulfonamide linkage, an ester linkage, a carbonate linkage, a carbamate linkage, an amide linkage, or a urea linkage.

[0020] Another object of the present invention is to provide a method for preparing the carbon nanotube dispersion.

[0021] Technical Solution

[0022] One embodiment of the present invention provides a carbon nanotube dispersion including carbon nanotubes, a first dispersant including nitrogen atoms, a second dispersant including a compound represented by the following Formula 1, and a solvent.

[0023] [Formula 1]

[0024]

[0025] in,

[0026] Ar1 and Ar6 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 aryl group,

[0027] Ar2 to Ar5 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 arylene group, and

[0028] L1 is an amino linkage, an ether linkage, a thiol linkage, a hydrazine linkage, a sulfinate linkage, a sulfonate linkage, a sulfonamide linkage, an ester linkage, a carbonate linkage, a carbamate linkage, an amide linkage, or a urea linkage.

[0029] Ar1 and Ar6 in Formula 1 may be respectively represented by the following Formula 2, Ar2 and Ar5 in Formula 1 may be respectively represented by the following Formula 3, and Ar3 and Ar4 in Formula 1 may be respectively represented by the following Formula 4.

[0030] [Formula 2]

[0031]

[0032] [Formula 3]

[0033]

[0034] [Formula 4]

[0035]

[0036] In formula 2,

[0037] R1 to R6 are the same as or different from each other and are each independently hydrogen; deuterium; halogen; cyano; sulfonate group; hydroxyl; amine; nitro; or a moiety attached to the azo group in Formula 1, provided that any one of R1 to R6 is a moiety attached to the azo group in Formula 1,

[0038] In formula 3,

[0039] R7 to R12 are the same as or different from each other and are each independently hydrogen; deuterium; halogen; cyano; sulfonate group; hydroxyl; amine; nitro; or a moiety attached to the azo group in Formula 1, provided that at least two of R7 to R12 are moieties attached to the azo group in Formula 1, and

[0040] In formula 4,

[0041] R13 to R20 are the same as or different from each other and are each independently hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; nitro group; a portion connected to the azo group in Formula 1; or a portion connected to L1 in Formula 1, provided that at least any one of R13 to R20 is a portion connected to the azo group in Formula 1, and at least one of the remaining portions of R13 to R20 other than the portion connected to the azo group in Formula 1 is a portion connected to L1 in Formula 1.

[0042] Among R1 to R6 in Formula 2, at least one of the remaining parts except the part connected to the azo group in Formula 1 may be a sulfonate group, among R7 to R12 in Formula 3, at least one of the remaining parts except the part connected to the azo group in Formula 1 may be a sulfonate group, and among R13 to R20 in Formula 4, at least one of the remaining parts except the parts connected to the azo group and L1 in Formula 1 may be a sulfonate group.

[0043] The second dispersant may include a compound represented by the following Formula 1-1.

[0044] [Formula 1-1]

[0045]

[0046] in,

[0047] R1 to R5, R7 to R10, and R13 to R18 are the same as or different from each other, and are each independently hydrogen; deuterium; halogen; cyano; sulfonate; hydroxyl; amine; or nitro.

[0048] The carbon nanotubes may be included in an amount of 0.05 parts by weight to 5 parts by weight, based on 100 parts by weight of the above carbon nanotube dispersion.

[0049] The BET specific surface area of ​​carbon nanotubes can be 800 m 2 / g to 2,000m 2 / g.

[0050] The first dispersant may be at least one selected from the group consisting of polyvinyl pyrrolidone, polyacrylic acid hydrazide, poly-N-vinyl-5-methyl Oxazolidinone, N-alkylpolyimine, N-acetylpolyimine, polyacrylamide, poly-L-lysine hydrobromide, benzyl-dodecyl-dimethylammonium chloride and polyethyleneimine.

[0051] The first dispersant may be included in an amount of about 0.01 parts by weight to about 10 parts by weight, based on 100 parts by weight of the above carbon nanotube dispersion.

[0052] The second dispersant may be included in an amount of about 0.001 parts by weight to about 9 parts by weight, based on 100 parts by weight of the above carbon nanotube dispersion.

[0053] The first dispersant and the second dispersant may be included in a weight ratio of about 100:10 to about 100:90.

[0054] The above carbon nanotube dispersion may have an initial viscosity measured at 25° C. and 1 rpm of 1 Pa·sec to 10 Pa·sec.

[0055] The viscosity increase rate of the above carbon nanotube dispersion represented by the following Equation 1 may be 15% or less.

[0056] [Equation 1]

[0057] Viscosity increase rate (%) = {(viscosity measured after standing at 25°C for 1 week - initial viscosity) / initial viscosity} × 100

[0058] Another embodiment of the present invention provides a method for preparing a carbon nanotube dispersion, the method comprising the steps of: (1) preparing a primary dispersion of carbon nanotubes by mixing carbon nanotubes, a first dispersant containing nitrogen atoms, a second dispersant containing a compound represented by Formula 1, and a solvent; and (2) dispersing the primary dispersion of carbon nanotubes to prepare a secondary dispersion of carbon nanotubes.

[0059] Beneficial effects

[0060] The carbon nanotube dispersion according to the present invention uses a first dispersant containing nitrogen atoms and a second dispersant containing a compound represented by Formula 1, and therefore, has the following characteristics: although carbon nanotubes having a large specific surface area are used, the viscosity of the dispersion changes little over time, the viscosity is relatively low, and the carbon nanotubes are uniformly and efficiently dispersed, and thus the particle size of the dispersed particles is small. DETAILED DESCRIPTION

[0061] Hereinafter, embodiments of the present invention will be described in detail. Prior to this, the terms or words used in this specification and claims should not be interpreted as being limited to their customary meanings or dictionary meanings, and should be interpreted as being consistent with the meaning and concept of the technical ideas of the present invention based on the principle that the inventor can appropriately define the concept of terms in order to explain his own invention in the best way. Therefore, it should be understood that the configuration described in the embodiments described in this specification is only one of the most preferred embodiments of the present invention and does not represent all technical ideas of the present invention, and therefore when submitting this application, various equivalents and modifications that can replace these may exist.

[0062] In this specification, the term "substituted" means that a hydrogen atom bonded to a carbon atom of a compound is changed to another substituent, and the position of the substitution is not limited as long as the position is a position where the hydrogen atom is substituted (i.e., a position where a substituent can be substituted), and when two or more substitutions are made, the two or more substituents may be the same as or different from each other.

[0063] In the present specification, the term "substituted or unsubstituted" means substituted or unsubstituted with one or more substituents selected from the group consisting of deuterium, halogen, cyano, linear or branched C1 to C60 alkyl, linear or branched C2 to C60 alkenyl, linear or branched C2 to C60 alkynyl, monocyclic or polycyclic C3 to C60 cycloalkyl, monocyclic or polycyclic C2 to C60 heterocycloalkyl, monocyclic or polycyclic C6 to C60 aryl, monocyclic or polycyclic C2 to C60 heteroaryl, C1 to C20 alkylamino, monocyclic or polycyclic C6 to C60 arylamino, and monocyclic or polycyclic C2 to C60 heteroarylamino, or substituted or unsubstituted with a substituent formed by linking two or more substituents selected from the substituents exemplified above.

[0064] Throughout the present specification, when a part is referred to as “comprising” a component, unless specifically stated otherwise, this does not mean that it does not include other components, but rather means that it may include other components.

[0065] Throughout this specification, "%" means % by weight unless otherwise specifically stated.

[0066] In this specification, the average particle size "D 50 " means the particle size corresponding to 50% of the volume accumulation. 50 The measurement can be performed, for example, using laser diffraction, which can generally measure particle sizes from the submicron range to several mm and can obtain results with high reproducibility and high resolution.

[0067] In this specification, the "specific surface area" is measured by Brunauer-Emmett-Teller analysis, and specifically can be calculated from the nitrogen adsorption amount at liquid nitrogen temperature (77K) using BELSORP-minoII of BEL Japan company.

[0068] Carbon nanotube dispersion

[0069] The carbon nanotube dispersion according to the present invention includes carbon nanotubes, a first dispersant containing nitrogen atoms, a second dispersant containing a compound represented by Formula 1, and a solvent. Hereinafter, each component of the carbon nanotube dispersion of the present invention will be described in detail.

[0070] (1) Carbon nanotubes

[0071] The term "carbon nanotube" used in the present invention refers to a secondary structure formed by assembling carbon nanotube units to form a bundle shape in whole or in part, wherein the carbon nanotube units are graphite sheets in the form of cylinders with nanometer-sized diameters and have sp 2 Bonding structure. At this time, depending on the angle and structure of the rolled graphite sheet, it can exhibit the properties of a conductor or a semiconductor. Carbon nanotube units can be divided into single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), and multi-walled carbon nanotubes (MWCNTs) based on the number of bonds forming the wall.

[0072] Unless otherwise specified, the term "bundle type" used in the present invention refers to a secondary shape in the form of a bundle or rope, in which a plurality of carbon nanotube units are arranged in a parallel manner with the longitudinal axes of the units substantially oriented in the same direction, or are twisted or tangled after arrangement. "Non-bundle type or tangled type" refers to a form in which carbon nanotube units are tangled without a specific shape (such as a bundle or rope).

[0073] Carbon nanotubes (CNTs) have high electrical conductivity, but they tend to aggregate due to van der Waals forces between the CNTs. Agglomeration prevents the proper formation of conductive paths within the electrode, and the amount of active material used to increase conductivity decreases, potentially reducing electrode performance, such as capacity. Consequently, commercialization of CNTs as a conductive material has been difficult.

[0074] The carbon nanotube dispersion according to the present invention includes a first dispersant containing nitrogen atoms and a second dispersant containing a compound represented by Formula 1, and thus can significantly reduce the initial viscosity of the carbon nanotube dispersion, suppress the change in viscosity over time, and simultaneously maintain a low particle size of dispersed particles.

[0075] The carbon nanotube dispersion according to one embodiment of the present invention may include at least one of single-walled carbon nanotubes, double-walled carbon nanotubes, and multi-walled carbon nanotubes as carbon nanotubes, but is not limited thereto, and specifically may include single-walled carbon nanotubes. Since single-walled carbon nanotubes or double-walled carbon nanotubes have a higher specific surface area than multi-walled carbon nanotubes, they are more effective in improving cycle characteristics when applied to secondary batteries.

[0076] At the same time, the carbon nanotubes can have an average diameter of, for example, 0.6 nm to 10 nm, preferably 0.8 nm to 5 nm, more preferably 0.8 nm to 3 nm, and can have an average diameter of 0.8 nm or more, 0.9 nm or more, 1.0 nm or more, 1.1 nm or more, 1.2 nm or more, 1.3 nm or more, 1.4 nm or more, 1.5 nm or more, 1.6 nm or more, 1.7 nm or more, 1.8 nm or more or 1.9 nm or more, and can have an average diameter of 3.0 nm or less, 2.9 nm or less, 2.8 nm or less, 2.7 nm or less, 2.6 nm or less, 2.5 nm or less, 2.4 nm or less, 2.3 nm or less, 2.2 nm or less, 2.1 nm or less or 2.0 nm or less.

[0077] In addition, the carbon nanotubes may have an average length of 0.5 μm to 20 μm, preferably 1 μm to 20 μm, more preferably 5 μm to 20 μm, and may have an average length of 5 μm or more, 7 μm or more, 9 μm or more, 11 μm or more, or 13 μm or more, and may have an average length of 20 μm or less, 18 μm or less, 16 μm or less, or 14 μm or less. If the average diameter and average length of the carbon nanotubes meet the above ranges, they are effective in reducing the viscosity of the dispersion and improving storage stability, and when applied to electrode active materials, excellent cycle characteristics can also be achieved.

[0078] In these cases, the average diameter of the carbon nanotubes can be measured by photographing the carbon nanotube powder with a scanning electron microscope, and the average length of the carbon nanotubes can be measured by photographing the carbon nanotube dispersion with a scanning electron microscope.

[0079] The above carbon nanotubes may be included in an amount of 0.05 to 5 parts by weight, based on a total of 100 parts by weight of the carbon nanotube dispersion, and may be included in an amount of 0.05 parts by weight or more, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, 0.5 parts by weight or more, 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 parts by weight or more, 0.9 parts by weight or more, 1.0 parts by weight or more, 1.1 parts by weight or more, 1.2 parts by weight or more, 1.3 parts by weight or more, 1.4 parts by weight or more, 1.5 parts by weight or more, 1.6 parts by weight or more, 1.7 parts by weight or more, 1.8 parts by weight or more, 1.9 parts by weight or more, 2.0 parts by weight or more, 2.1 parts by weight or more, 2.2 parts by weight or more , 2.3 parts by weight or more, 2.4 parts by weight or more or 2.5 parts by weight or more, and may be included in the following amounts: 5 parts by weight or less, 4.9 parts by weight or less, 4.8 parts by weight or less, 4.7 parts by weight or less, 4.6 parts by weight or less, 4.5 parts by weight or less, 4.4 parts by weight or less, 4.3 parts by weight or less, 4.2 parts by weight or less, 4.1 parts by weight or less, 4 parts by weight or less, 3.9 parts by weight or less, 3.8 parts by weight or less, 3.7 parts by weight or less, 3.6 parts by weight or less, 3.5 parts by weight or less, 3.4 parts by weight or less, 3.3 parts by weight or less, 3.2 parts by weight or less, 3.1 parts by weight or less, 3 parts by weight or less, 2.9 parts by weight or less, 2.8 parts by weight or less, 2.7 parts by weight or less or 2.6 parts by weight or less. If the content of the carbon nanotubes satisfies the above range, the effect of improving the viscosity of the dispersion and the effect of improving the conductivity of a secondary battery manufactured by the carbon nanotube dispersion are excellent.

[0080] The BET specific surface area of ​​carbon nanotubes can be 800 m 2 / g to 2,000m 2 / g, for example, it can be 800m 2 / g or greater, 810m 2 / g or greater, 820m 2 / g or greater, 830m 2 / g or greater, 840m 2 / g or greater, 850m 2 / g or greater, 860m 2 / g or greater, 870m 2 / g or greater, 880m 2 / g or greater, 890m 2 / g or greater, 900m 2 / g or greater, 910m 2 / g or greater, 920m 2 / g or greater, 930m 2 / g or greater, 940m 2 / g or greater, 950m 2 / g or greater, 960m 2 / g or greater, 970m 2 / g or greater, 980m 2 / g or greater, 990m 2 / g or greater, 1,000m 2 / g or greater, 1,010m 2 / g or greater, 1,020m 2 / g or greater, 1,030m 2 / g or greater, 1,040m 2 / g or greater, 1,050m 2 / g or greater, 1,060m 2 / g or greater, 1,070m 2 / g or greater, 1,080m 2 / g or greater, 1,090m 2 / g or more, 1,100m 2 / g or greater, 1,110m 2 / g or greater, 1,120m 2 / g or greater, 1,130m 2 / g or greater, 1,140m 2 / g or greater, 1,150m 2 / g or greater, 1,160m 2 / g or greater, 1,170m 2 / g or greater, 1,180m 2 / g or greater, 1,190m 2 / g or greater, 1,200m 2 / g or greater, 1,210m 2 / g or greater, 1,220m 2 / g or greater, 1,230m 2 / g or greater, 1,240m 2 / g or greater, 1,250m 2 / g or greater, 1,260m 2 / g or greater, 1,270m 2 / g or greater, 1,280m 2 / g or greater, 1,290m 2 / g or greater, 1,300m 2 / g or greater, 1,310m 2 / g or greater, 1,320m2 / g or greater, 1,330m 2 / g or greater, 1,340m 2 / g or greater, 1,350m 2 / g or greater, 1,360m 2 / g or greater, 1,370m 2 / g or greater, 1,380m 2 / g or greater, 1,390m 2 / g or greater or 1,400m 2 / g or more, and can be 2,000m 2 / g or less, 1,990m 2 / g or less, 1,980m 2 / g or less, 1,970m 2 / g or less, 1,960m 2 / g or less, 1,950m 2 / g or less, 1,940m 2 / g or less, 1,930m 2 / g or less, 1,920m 2 / g or less, 1,910m 2 / g or less, 1,900m 2 / g or less, 1,890m 2 / g or less, 1,880m 2 / g or less, 1,870m 2 / g or less, 1,860m 2 / g or less, 1,850m 2 / g or less, 1,840m 2 / g or less, 1,830m 2 / g or less, 1,820m 2 / g or less, 1,810m 2 / g or less, 1,800m 2 / g or less, 1,790m 2 / g or less, 1,780m 2 / g or less, 1,770m 2 / g or less, 1,760m 2 / g or less, 1,750m 2 / g or less, 1,740m 2 / g or less, 1,730m 2 / g or less, 1,720m 2 / g or less, 1,710m 2 / g or less, 1,700m 2 / g or less, 1,690m 2 / g or less, 1,680m 2 / g or less, 1,670m 2 / g or less, 1,660m 2 / g or less, 1,650m 2 / g or less, 1,640m 2 / g or less, 1,630m 2 / g or less, 1,620m 2 / g or less, 1,610m 2 / g or less, 1,600m 2 / g or less, 1,590m 2 / g or less, 1,580m 2 / g or less, 1,570m 2 / g or less, 1,560m 2 / g or less, 1,550m 2 / g or less, 1,540m 2 / g or less, 1,530m 2 / g or less, 1,520m 2 / g or less, 1,510m 2 / g or less, 1,500m 2 / g or less, 1,490m 2 / g or less, 1,480m 2 / g or less, 1,470m 2 / g or less, 1,460m 2 / g or less, 1,450m 2 / g or less, 1,440m 2 / g or less, 1,430m 2 / g or less, 1,420m 2 / g or less or 1,410m 2 If carbon nanotubes having a high BET specific surface area as described above are used, formation of a conductive network between electrode active materials is excellent, and thus the cycle characteristics of a secondary battery manufactured using the carbon nanotube dispersion can be improved.

[0081] The carbon nanotube dispersion according to one embodiment of the present invention can have a relatively high carbon nanotube content because the carbon nanotubes can be evenly dispersed. If a carbon nanotube dispersion with a low carbon nanotube content is used in the preparation of an electrode slurry, the solid content of the prepared electrode slurry is reduced, so the thickness (wet thickness) before the electrode slurry is applied and dried becomes thicker, and the roller pressing ratio measured after the subsequent drying and rolling process becomes higher, and therefore the difference in the thickness ratio before and after drying and rolling becomes larger. Therefore, if the roller pressing ratio increases, the composition within the slurry containing the positive electrode active material may be damaged during the process, which may lead to a problem of reduced battery performance.

[0082] (2) Dispersant

[0083] The carbon nanotube dispersion according to the present invention contains a dispersant to improve dispersibility of the carbon nanotubes, and includes a first dispersant containing nitrogen atoms and a second dispersant containing a compound represented by the following Formula 1 as dispersants.

[0084] [Formula 1]

[0085]

[0086] in,

[0087] Ar1 and Ar6 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 aryl group,

[0088] Ar2 to Ar5 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 arylene group, and

[0089] L1 is an amino linkage, an ether linkage, a thiol linkage, a hydrazine linkage, a sulfinate linkage, a sulfonate linkage, a sulfonamide linkage, an ester linkage, a carbonate linkage, a carbamate linkage, an amide linkage, or a urea linkage.

[0090] In the carbon nanotube dispersion, the first dispersant and the second dispersant play a role in improving the dispersibility of the carbon nanotubes so that the carbon nanotubes can be uniformly dispersed in the dispersion without agglomeration, and in particular, play a role in suppressing the change in viscosity of the carbon nanotube dispersion over time and reducing the average particle size of the dispersed particles.

[0091] In the carbon nanotube dispersion according to one embodiment of the present invention, the first dispersant containing nitrogen atoms may be soluble in an aqueous solvent to be described later, and may be, for example, at least one selected from the group consisting of polyvinyl pyrrolidone, polyacrylic acid hydrazide, poly-N-vinyl-5-methyl Oxazolidinone, N-alkylpolyimine, N-acetylpolyimine, polyacrylamide, poly-L-lysine hydrobromide, benzyl-dodecyl-dimethylammonium chloride and polyethyleneimine, preferably polyvinylpyrrolidone. The carbon nanotube dispersion according to one embodiment of the present invention can show the effect of improving the viscosity of the dispersion and the effect of suppressing the change of viscosity over time by containing the first dispersant containing nitrogen atoms.

[0092] In one embodiment of the present invention, the first dispersant may be included in an amount of 0.01 to 10 parts by weight, based on 100 parts by weight of the carbon nanotube dispersion. For example, it may be included in an amount of 0.01 parts by weight or more, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, 0.5 parts by weight or more, 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 parts by weight or more, 0.9 parts by weight or more, 1 part by weight or more, 1.1 parts by weight or more, 1.2 parts by weight or more, 1.3 parts by weight or more, 1.4 parts by weight or more, 1.5 parts by weight or more, 1.6 parts by weight or more, 1.7 parts by weight or more. , 1.8 parts by weight or more, 1.9 parts by weight or more, 2 parts by weight or more, 2.1 parts by weight or more, 2.2 parts by weight or more, 2.3 parts by weight or more, 2.4 parts by weight or more, 2.5 parts by weight or more, 2.6 parts by weight or more, 2.7 parts by weight or more, 2.8 parts by weight or more, 2.9 parts by weight or more, 3 parts by weight or more, 3.1 parts by weight or more, 3.2 parts by weight or more, 3.3 parts by weight or more, 3.4 parts by weight or more, 3.5 parts by weight or more, 3.6 parts by weight or more, 3.7 parts by weight or more, 3.8 parts by weight or more, 3.9 parts by weight or more, 4 parts by weight or more, 4.1 parts by weight or more, 4.2 parts by weight or more, 4.3 parts by weight or more parts by weight or less, 4.4 parts by weight or more, 4.5 parts by weight or more, 4.6 parts by weight or more, 4.7 parts by weight or more, 4.8 parts by weight or more, 4.9 parts by weight or more, or 5 parts by weight or more, and may be contained in the following amounts: 10 parts by weight or less, 9.9 parts by weight or less, 9.8 parts by weight or less, 9.7 parts by weight or less, 9.6 parts by weight or less, 9.5 parts by weight or less, 9.4 parts by weight or less, 9.3 parts by weight or less, 9.2 parts by weight or less, 9.1 parts by weight or less, 9 parts by weight or less, 8.9 parts by weight or less, 8.8 parts by weight or less, 8.7 parts by weight or less, 8.6 parts by weight or less, 8.5 parts by weight or less, 8.4 parts by weight or less, 8.3 parts by weight or less, 8.2 parts by weight or less, 8.1 parts by weight or less, 8 parts by weight or less, 7.9 parts by weight or less, 7.8 parts by weight or less, 7.7 parts by weight or less, 7.6 parts by weight or less, 7.5 parts by weight or less, 7.4 parts by weight or less, 7.3 parts by weight or less, 7.2 parts by weight or less, 7.1 parts by weight or less, 7 parts by weight or less, 6.9 parts by weight or less, 6.8 parts by weight or less, 6.7 parts by weight or less, 6.6 parts by weight or less, 6.5 parts by weight or less, 6.4 parts by weight or less, 6.3 parts by weight or less, 6.2 parts by weight or less, 6.1 parts by weight or less, 6 parts by weight or less, 5.9 parts by weight or less, 5.8 parts by weight or less, 5.7 parts by weight or less, 5.6 parts by weight or less, 5.5 parts by weight or less, 5.4 parts by weight or less, 5.3 parts by weight or less, 5.2 parts by weight or less, or 5.1 parts by weight or less.

[0093] If the content of the first dispersant is less than 0.01 parts by weight based on 100 parts by weight of the carbon nanotube dispersion, there may be a problem that the content of the dispersant is insufficient, so that the dispersion does not have a sufficient dispersing effect, and thus the viscosity of the dispersion does not become low, and the viscosity increases over time. If the content of the first dispersant exceeds 10 parts by weight, there may be a problem that the viscosity of the dispersion becomes high due to agglomeration between solids in the dispersion caused by the excessive first dispersant content.

[0094] Furthermore, in order to solve the problem that the viscosity of the dispersion increases as the content of carbon nanotubes increases in a carbon nanotube dispersion containing only a first dispersant, the carbon nanotube dispersion according to one embodiment of the present invention further contains a second dispersant containing a compound represented by the following Formula 1 in addition to the first dispersant, and therefore, it has excellent dispersibility compared to a conventional carbon nanotube dispersion using only a dispersant, and it can exhibit effects such as less agglomeration of particles of the slurry composition and a low sedimentation velocity.

[0095] [Formula 1]

[0096]

[0097] in,

[0098] Ar1 and Ar6 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 aryl group,

[0099] Ar2 to Ar5 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 arylene group, and

[0100] L1 is an amino linkage, an ether linkage, a thiol linkage, a hydrazine linkage, a sulfinate linkage, a sulfonate linkage, a sulfonamide linkage, an ester linkage, a carbonate linkage, a carbamate linkage, an amide linkage, or a urea linkage.

[0101] In one embodiment of the present invention, Ar1 in Formula 1 may be a substituted or unsubstituted C6 to C30 aryl group.

[0102] In one embodiment of the present invention, Ar1 in Formula 1 may be a substituted or unsubstituted C6 to C20 aryl group.

[0103] In one embodiment of the present invention, Ar1 in Formula 1 may be a substituted or unsubstituted C6 to C10 aryl group.

[0104] In one embodiment of the present invention, Ar1 in Formula 1 may be a substituted or unsubstituted phenyl group.

[0105] In one embodiment of the present invention, Ar6 in Formula 1 may be a substituted or unsubstituted C6 to C30 aryl group.

[0106] In one embodiment of the present invention, Ar6 in Formula 1 may be a substituted or unsubstituted C6 to C20 aryl group.

[0107] In one embodiment of the present invention, Ar6 in Formula 1 may be a substituted or unsubstituted C6 to C10 aryl group.

[0108] In one embodiment of the present invention, Ar6 in Formula 1 may be a substituted or unsubstituted phenyl group.

[0109] In one embodiment of the present invention, Ar2 in Formula 1 may be a substituted or unsubstituted C6 to C30 arylene group.

[0110] In one embodiment of the present invention, Ar2 in Formula 1 may be a substituted or unsubstituted C6 to C20 arylene group.

[0111] In one embodiment of the present invention, Ar2 in Formula 1 may be a substituted or unsubstituted C6 to C10 arylene group.

[0112] In one embodiment of the present invention, Ar2 in Formula 1 may be a substituted or unsubstituted phenylene group.

[0113] In one embodiment of the present invention, Ar3 in Formula 1 may be a substituted or unsubstituted C6 to C30 arylene group.

[0114] In one embodiment of the present invention, Ar3 in Formula 1 may be a substituted or unsubstituted C6 to C20 arylene group.

[0115] In one embodiment of the present invention, Ar3 in Formula 1 may be a substituted or unsubstituted C6 to C10 arylene group.

[0116] In one embodiment of the present invention, Ar3 in Formula 1 may be a substituted or unsubstituted phenylene group.

[0117] In one embodiment of the present invention, Ar4 in Formula 1 may be a substituted or unsubstituted C6 to C30 arylene group.

[0118] In one embodiment of the present invention, Ar4 in Formula 1 may be a substituted or unsubstituted C6 to C20 arylene group.

[0119] In one embodiment of the present invention, Ar4 in Formula 1 may be a substituted or unsubstituted C6 to C10 arylene group.

[0120] In one embodiment of the present invention, Ar4 in Formula 1 may be a substituted or unsubstituted phenylene group.

[0121] In one embodiment of the present invention, Ar5 in Formula 1 may be a substituted or unsubstituted C6 to C30 arylene group.

[0122] In one embodiment of the present invention, Ar5 in Formula 1 may be a substituted or unsubstituted C6 to C20 arylene group.

[0123] In one embodiment of the present invention, Ar5 in Formula 1 may be a substituted or unsubstituted C6 to C10 arylene group.

[0124] In one embodiment of the present invention, Ar5 in Formula 1 may be a substituted or unsubstituted phenylene group.

[0125] In one embodiment of the present invention, L1 in Formula 1 may be a urea linkage.

[0126] In addition, in one embodiment of the present invention, Ar1 and Ar6 in Formula 1 can be respectively represented by the following Formula 2, Ar2 and Ar5 in Formula 1 can be respectively represented by the following Formula 3, and Ar3 and Ar4 in Formula 1 can be respectively represented by the following Formula 4.

[0127] [Formula 2]

[0128]

[0129] [Formula 3]

[0130]

[0131] [Formula 4]

[0132]

[0133] In formula 2,

[0134] R1 to R6 are the same as or different from each other and are each independently hydrogen; deuterium; halogen; cyano; sulfonate group; hydroxyl; amine; nitro; or a moiety attached to the azo group in Formula 1, provided that any one of R1 to R6 is a moiety attached to the azo group in Formula 1,

[0135] In formula 3,

[0136] R7 to R12 are the same as or different from each other and are each independently hydrogen; deuterium; halogen; cyano; sulfonate group; hydroxyl; amine; nitro; or a moiety attached to the azo group in Formula 1, provided that at least two of R7 to R12 are moieties attached to the azo group in Formula 1, and

[0137] In formula 4,

[0138] R13 to R20 are the same as or different from each other and are each independently hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; nitro group; a portion connected to the azo group in Formula 1; or a portion connected to L1 in Formula 1, provided that at least any one of R13 to R20 is a portion connected to the azo group in Formula 1, and any one of the remaining portions of R13 to R20 other than the portion connected to the azo group in Formula 1 is a portion connected to L1 in Formula 1.

[0139] In one embodiment of the present invention, R1 to R6 in Formula 2 are the same as or different from each other and are each independently hydrogen; deuterium; a sulfonate group; a hydroxyl group; or a portion connected to the azo group in Formula 1, provided that any one of R1 to R6 can be a portion connected to the azo group in Formula 1.

[0140] In one embodiment of the present invention, R7 to R12 in Formula 3 are the same as or different from each other and are each independently hydrogen; deuterium; a sulfonate group; a hydroxyl group; or a portion connected to the azo group in Formula 1, provided that at least two of R7 to R12 can be a portion connected to the azo group in Formula 1.

[0141] In one embodiment of the present invention, R13 to R20 in Formula 4 are the same as or different from each other and are each independently hydrogen; deuterium; a sulfonate group; a hydroxyl group; a portion connected to the azo group in Formula 1; or a portion connected to L1 in Formula 1, provided that at least any one of R13 to R20 may be the portion connected to the azo group in Formula 1, and any one of the remaining portions of R13 to R20 except the portion connected to the azo group in Formula 1 may be the portion connected to L1 of Formula 1.

[0142] In one embodiment of the present invention, among R1 to R6 in Formula 2, at least one of the remaining parts except the part connected to the azo group in Formula 1 may be a sulfonate group, among R7 to R12 in Formula 3, at least one of the remaining parts except the part connected to the azo group in Formula 1 may be a sulfonate group, and among R13 to R20 in Formula 4, at least one of the remaining parts except the parts connected to the azo group and L1 in Formula 1 may be a sulfonate group.

[0143] In one embodiment of the present invention, if at least one of R1 to R20 in Formulae 2 to 4 is a sulfonate group, the anion of the sulfonate group may be in the form of a salt combined with a metal cation, and specifically, may be a sodium salt of the sulfonate group.

[0144] In one embodiment of the present invention, the second dispersant may include a compound represented by the following Formula 1-1.

[0145] [Formula 1-1]

[0146]

[0147] in,

[0148] R1 to R5, R7 to R10, and R13 to R18 are the same as or different from each other, and are each independently hydrogen; deuterium; halogen; cyano; sulfonate; hydroxyl; amine; or nitro.

[0149] In one embodiment of the present invention, R1 to R5 are the same as or different from each other and are each independently hydrogen; or a sulfonate group, provided that at least one of R1 to R5 can be a sulfonate group.

[0150] In one embodiment of the present invention, R7 to R10 are the same as or different from each other and are each independently hydrogen; or a sulfonate group, provided that at least one of R7 to R10 may be a sulfonate group.

[0151] In one embodiment of the present invention, R13 to R18 may be the same as or different from each other, and may each independently be hydrogen; a hydroxyl group; or a sulfonate group.

[0152] In one embodiment of the present invention, the second dispersant may include a compound represented by the following Formula 5 (Direct Red 80).

[0153] [Formula 5]

[0154]

[0155] Since the compound represented by Formula 1 contained in the second dispersant contains different aryl groups and arylene groups connected by an azo group, it stably generates π-π interactions with the carbon nanotubes in a local area, and thus it can fully enhance the binding force between the dispersant and the carbon nanotubes and reduce the content of excess dispersant that is not effectively adsorbed on the surface of the carbon nanotubes, thereby preventing agglomeration between the remaining dispersants.

[0156] Furthermore, in the carbon nanotube dispersion according to one embodiment of the present invention, since the compound represented by Formula 1 contained in the second dispersant contains a hydroxyl group, it forms a hydrogen bond with the solvent in the dispersion, thereby allowing the "carbon nanotube-dispersant" complex to stably maintain a dispersed state in the solvent.

[0157] Furthermore, in the carbon nanotube dispersion according to one embodiment of the present invention, since the compound represented by Formula 1 contained in the second dispersant contains six or more sulfonate groups, since the dispersant is ionized when dissolved in the solvent, it forms electrostatic repulsion between the sulfonate anions, thereby preventing agglomeration between adjacent dispersants, and thus allowing the "carbon nanotube-dispersant" composite to remain stably dispersed in the solvent.

[0158] If the carbon nanotube dispersion does not contain the second dispersant according to the present invention, the area of ​​the surface of the carbon nanotubes that is not sufficiently covered by the dispersant may increase, and thus, a strong binding force greater than an appropriate level may be generated between the carbon nanotubes, and the viscosity of the dispersion may become high as a result of agglomeration between the carbon nanotubes.

[0159] In one embodiment of the present invention, the second dispersant may be included in an amount of 0.001 to 9 parts by weight, based on 100 parts by weight of the carbon nanotube dispersion. For example, it may be included in an amount of 0.001 parts by weight or more, 0.01 parts by weight or more, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, 0.5 parts by weight or more, 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 parts by weight or more, 0.9 parts by weight or more, 1 part by weight or more, 1.1 parts by weight or more, 1.2 parts by weight or more, 1.3 parts by weight or more, 1.4 parts by weight or more, 1.5 parts by weight or more, 1.6 parts by weight or more, parts by weight or more, 1.7 parts by weight or more, 1.8 parts by weight or more, 1.9 parts by weight or more, 2 parts by weight or more, 2.1 parts by weight or more, 2.2 parts by weight or more, 2.3 parts by weight or more, 2.4 parts by weight or more, 2.5 parts by weight or more, 2.6 parts by weight or more, 2.7 parts by weight or more, 2.8 parts by weight or more, 2.9 parts by weight or more, 3 parts by weight or more, 3.1 parts by weight or more, 3.2 parts by weight or more, 3.3 parts by weight or more, 3.4 parts by weight or more, 3.5 parts by weight or more, 3.6 parts by weight or more, 3.7 parts by weight or more, 3.8 parts by weight or more, 3.9 parts by weight or more, 4 parts by weight or more, 4.1 parts by weight or more , 4.2 parts by weight or more, 4.3 parts by weight or more, 4.4 parts by weight or more, or 4.5 parts by weight or more, and may be contained in the following amounts: 9 parts by weight or less, 8.9 parts by weight or less, 8.8 parts by weight or less, 8.7 parts by weight or less, 8.6 parts by weight or less, 8.5 parts by weight or less, 8.4 parts by weight or less, 8.3 parts by weight or less, 8.2 parts by weight or less, 8.1 parts by weight or less, 8 parts by weight or less, 7.9 parts by weight or less, 7.8 parts by weight or less, 7.7 parts by weight or less, 7.6 parts by weight or less, 7.5 parts by weight or less, 7.4 parts by weight or less, 7.3 parts by weight or less, 7.2 parts by weight or less, 7.1 parts by weight or less. Parts by weight or less, 7 parts by weight or less, 6.9 parts by weight or less, 6.8 parts by weight or less, 6.7 parts by weight or less, 6.6 parts by weight or less, 6.5 parts by weight or less, 6.4 parts by weight or less, 6.3 parts by weight or less, 6.2 parts by weight or less, 6.1 parts by weight or less, 6 parts by weight or less, 5.9 parts by weight or less, 5.8 parts by weight or less, 5.7 parts by weight or less, 5.6 parts by weight or less, 5.5 parts by weight or less, 5.4 parts by weight or less, 5.3 parts by weight or less, 5.2 parts by weight or less, 5.1 parts by weight or less, 5 parts by weight or less, 4.9 parts by weight or less, 4.8 parts by weight or less, 4.7 parts by weight or less, or 4.6 parts by weight or less.

[0160] If the content of the second dispersant is less than 0.1 parts by weight based on 100 parts by weight of the carbon nanotube dispersion, there may be a problem that the viscosity of the dispersion may not be low due to an ineffective dispersion effect, and the viscosity may increase over time. If the content of the second dispersant exceeds 10 parts by weight, there may be a problem that due to the excessive content of the second dispersant, agglomeration occurs between solid components in the dispersion, thereby increasing the viscosity of the dispersion.

[0161] In one embodiment of the present invention, the first dispersant and the second dispersant in the carbon nanotube dispersion can be included in a weight ratio of 100:10 to 100:90, for example, the ratio of the first dispersant to the second dispersant can be 100:10 or greater, 100:15 or greater, 100:17.65 or greater, 100:20 or greater, 100:25 or greater, 100:30 or greater, 100:33.33 or greater, 100:35 or greater, 100:40 or greater, 100:45 or greater, 100:50 or greater or 100:55 or greater, and the ratio of the first dispersant to the second dispersant can be 100:90 or less, 100:85 or less, 100:80 or less, 100:75 or less, 100:70 or less, 100:65 or less or 100:60 or less.

[0162] If the contents of the first dispersant and the second dispersant are included in the carbon nanotube dispersion at the above weight ratio, the carbon nanotubes are uniformly dispersed in the carbon nanotube dispersion, and thus the viscosity can be maintained at a constant level over time at a low viscosity.

[0163] (3) Solvent

[0164] The solvent of the carbon nanotube dispersion according to one embodiment of the present invention is a dispersion medium for dispersing the carbon nanotubes, the first dispersant, and the second dispersant, and is used to pre-disperse the carbon nanotubes in a powder state and supply them as a carbon nanotube dispersion to prevent agglomeration that occurs when the carbon nanotubes in a powder state are directly used to prepare an electrode slurry composition.

[0165] The solvent can dissolve or disperse the carbon nanotubes, the first dispersant, and the second dispersant to a certain level or higher. The aqueous solvent can be, for example, water, in an amount such that the electrode slurry composition has an appropriate viscosity, taking into account the coating properties of the electrode slurry composition prepared later using the carbon nanotube dispersion.

[0166] The carbon nanotube dispersion according to one embodiment of the present invention enables the first dispersant and the second dispersant to uniformly disperse the carbon nanotubes in the solvent as described above, and thus can reduce the average particle size distribution of dispersed particles (e.g., a composite of carbon nanotubes and each dispersant) contained in the dispersion.

[0167] The average particle size distribution (D 50 ) can be, for example, 0.5 μm to 10 μm, 1 μm to 10 μm, 1 μm to 8 μm, and preferably 1 μm to 5 μm.

[0168] The carbon nanotube dispersion of the present invention comprising the above components has excellent dispersibility, and thus the viscosity of the dispersion is low, and the degree of increase in viscosity over time is small.

[0169] The initial viscosity of the carbon nanotube dispersion measured at 25° C. and 1 rpm using a viscometer (viscometer TV-25, rotor code 01, manufactured by TOKI SANGYO company) may be 1 Pa.s to 10 Pa.s, for example, 1 Pa.s or more, 1.1 Pa.s or more, 1.2 Pa.s or more, 1.3 Pa.s or more, 1.4 Pa.s or more, 1.5 Pa.s or more, 1.6 Pa.s or more, 1.7 Pa.s or more, 1.8 Pa.s or more, 1.9 Pa.s or more, 2 Pa.s or more, 2.1 Pa.s or more, 2.2 Pa.s or more, 2.3 Pa.s or more, 2.4 Pa.s or more, 2.5 Pa.s or more, 2.6 Pa.s or more, 2.7 Pa.s or more, .7Pa·second or more, 2.8Pa·second or more, 2.9Pa·second or more, 3Pa·second or more, 3.1Pa·second or more, 3.2Pa·second or more, 3.3Pa·second or more, 3.4Pa·second or more, 3.5Pa·second or more, 3.6Pa·second or more, 3.7Pa·second or more, 3.8Pa·second or more, 3.9Pa·second or more, 4Pa·second or more, 4.1Pa·second or more, 4.2Pa·second or more, 4.3Pa·second or more, 4.4Pa·second, 4.5Pa·second or more, 4.6Pa·second or more, 4.7Pa·second or more, 4.8Pa·second or more, 4.9Pa·second or more ·seconds or more, 5.1Pa·seconds or more, 5.2Pa·seconds or more, 5.3Pa·seconds or more, 5.4Pa·seconds or more or 5.5Pa·seconds or more, and may be 10Pa·seconds or less, 9.9Pa·seconds or less, 9.8Pa·seconds or less, 9.7Pa·seconds or less, 9.6Pa·seconds or less, 9.5Pa·seconds or less, 9.4Pa·seconds or less, 9.3Pa·seconds or less, 9.2Pa·seconds or less, 9.1Pa·seconds or less, 9Pa·seconds or less, 8.9Pa·seconds or less, 8.8Pa·seconds or less, 8.7Pa·seconds or less, 8.6Pa·seconds or less, 8 .5 Pa·second or less, 8.4 Pa·second or less, 8.3 Pa·second or less, 8.2 Pa·second or less, 8.1 Pa·second or less, 8 Pa·second or less, 7.9 Pa·second or less, 7.8 Pa·second or less, 7.7 Pa·second or less, 7.6 Pa·second or less, 7.5 Pa·second or less, 7.4 Pa·second or less, 7.3 Pa·second or less, 7.2 Pa·second or less, 7.1 Pa·second or less, 7 Pa·second or less, 6.9 Pa·second or less, 6.8 Pa·second or less, 6.7 Pa·second or less, 6.6 Pa·second or less, 6.5 Pa·second or less, 6.4 Pa·second or less, 6.3 Pa·s or less, 6.2 Pa·s or less, 6.1 Pa·s or less, 6 Pa·s or less, 5.9 Pa·s or less, 5.8 Pa·s or less, 5.7 Pa·s or less, or 5.6 Pa·s or less. If the carbon nanotube dispersion has an initial viscosity within the above range, electrode slurry can be manufactured more smoothly using it, and the electrode slurry containing the carbon nanotube dispersion can have an appropriate viscosity for forming an electrode.

[0170] Furthermore, the viscosity increase rate of the carbon nanotube dispersion when left at 25° C. for one week, as calculated by the following equation 1, may be 15% or less. Specifically, the viscosity increase rate may be 15% or less, 14.5% or less, 14% or less, 13.5% or less, 13% or less, 12.5% ​​or less, 12.3% or less, 12% or less, 11.5% or less, 11% or less, 10.5% or less, 10% or less. , 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7% or less, 6.8% or less, 6.5% or less, 6.1% or less, 6% or less, 5.5% or less, 5% or less, 4.5% or less, 4% or less, 3.5% or less, 3% or less, 2.5% or less, 2.4% or less, 2% or less, 1.5% or less or 1% or less.

[0171] [Equation 1]

[0172] Viscosity increase rate (%) = {(viscosity measured after standing at 25°C for 1 week - initial viscosity) / initial viscosity} × 100

[0173] At this time, the viscosity after standing for 1 week and the initial viscosity were measured at 25° C. and 1 rpm.

[0174] Preparation method of carbon nanotube dispersion

[0175] Hereinafter, a method for preparing a carbon nanotube dispersion according to one embodiment of the present invention will be described.

[0176] The method for preparing a carbon nanotube dispersion according to the present invention includes the following steps: (1) preparing a primary dispersion of carbon nanotubes by mixing carbon nanotubes, a first dispersant containing nitrogen atoms, a second dispersant containing a compound represented by the following Formula 1, and a solvent; and (2) dispersing the primary dispersion of carbon nanotubes to prepare a secondary dispersion of carbon nanotubes.

[0177] [Formula 1]

[0178]

[0179] in,

[0180] Ar1 and Ar6 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 aryl group,

[0181] Ar2 to Ar5 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 arylene group, and

[0182] L1 is an amino linkage, an ether linkage, a thiol linkage, a hydrazine linkage, a sulfinate linkage, a sulfonate linkage, a sulfonamide linkage, an ester linkage, a carbonate linkage, a carbamate linkage, an amide linkage, or a urea linkage.

[0183] In step (1), carbon nanotubes, a first dispersant containing nitrogen atoms, a second dispersant containing a compound represented by the above formula 1, and a solvent are mixed to prepare a primary dispersion of carbon nanotubes. The step of preparing the primary dispersion of carbon nanotubes is performed by a wet process in which the components are uniformly mixed.

[0184] Since the detailed descriptions of the carbon nanotubes, the first dispersant containing nitrogen atoms, the second dispersant containing the compound represented by the above Formula 1, and the solvent according to the preparation method of the carbon nanotube dispersion are the same as those described above, the detailed descriptions will be omitted below.

[0185] The mixing of the primary dispersion for preparing carbon nanotubes can be carried out using a conventional mixing method, specifically, a mixing apparatus such as a small mixer, a jar mixer, a Hobert mixer, a planetary mixer, a butterfly mixer, a stone mill, a homogenizer, a bead mill, a ball mill, a basket mill, an attritor, a universal stirrer, a transparent mixer or a TK mixer, and can include a step of mixing at a rotation speed of 300 rpm to 5,000 rpm for 30 minutes to 7 hours.

[0186] Furthermore, when mixing to prepare a primary dispersion of carbon nanotubes, a cavitation dispersion treatment may be performed to improve the miscibility of the carbon nanotubes with the solvent, or the dispersibility of the carbon nanotubes in the solvent. Cavitation dispersion is a dispersion method that utilizes shock waves generated by the explosion of vacuum bubbles formed in water when high energy is applied to the liquid. This dispersion method allows the carbon nanotubes to be dispersed without compromising their properties. Specifically, cavitation dispersion can be performed using ultrasonic waves, jet milling, or shear dispersion.

[0187] The step of preparing the primary dispersion of carbon nanotubes can be performed at a temperature such that the physical properties of the mixture (including viscosity) do not change due to evaporation of the solvent. For example, it can be performed at a temperature of 50°C or lower, more specifically, 5°C to 50°C.

[0188] In step (2), the primary dispersion of carbon nanotubes is dispersed to prepare a secondary dispersion of carbon nanotubes.

[0189] The process of preparing the secondary dispersion of carbon nanotubes can be carried out by methods such as a ball mill, a bead mill, a disk mill or a basket mill, a high-pressure disperser (high-pressure homogenizer), and more specifically, it can be carried out by a dispersion method using a high-pressure disperser (high-pressure homogenizer).

[0190] The dispersion by the high-pressure disperser is achieved by, for example, pressurizing the mixture with a plunger pump of the high-pressure disperser and pushing it out through the gap of the dispersion valve, thereby causing forces such as cavitation, shear, impact, and explosion when passing through the gap.

[0191] The dispersion process can be carried out according to the degree of dispersion of the carbon nanotube dispersion, and specifically, it can be carried out at a pressure of 5,000 psi to 30,000 psi for 30 minutes to 120 minutes, more specifically, 60 minutes to 90 minutes, and the above process can be repeated 1 to 10 times.

[0192] The carbon nanotube dispersion according to the present invention can mean a secondary dispersion of carbon nanotubes.

[0193] Electrode paste composition for lithium secondary battery

[0194] In addition, the present invention provides an electrode paste composition for a lithium secondary battery, which includes the carbon nanotube dispersion and an electrode active material.

[0195] The electrode paste composition for a lithium secondary battery can be a positive electrode paste composition or a negative electrode paste composition, and specifically, it can be a negative electrode paste composition.

[0196] The electrode paste composition for a lithium secondary battery can include the carbon nanotube dispersion, a positive electrode active material or a negative electrode active material as an electrode active material, a binder, a solvent, and / or other additives (as needed).

[0197] As the positive electrode active material, positive electrode active materials well-known in the art can be used without limitation. For example, lithium cobalt-based oxides, lithium nickel-based oxides, lithium manganese-based oxides, lithium iron phosphate oxides, lithium nickel manganese cobalt-based oxides, or combinations thereof can be used. Specifically, as the positive electrode active material, LiCoO2, LiNiO2, LiMn2O4, LiCoPO4, LiFePO4, and LiNiaMnbCocO2 (where 0 < a, b, c < 1) can be used, but are not limited thereto. [[ID=The negative electrode active material may include one or more negative electrode active materials selected from the following: natural graphite, artificial graphite, carbonaceous material; lithium-containing titanium composite oxide (LTO); metal (Me) of Si, Sn, Li, Zn, Mg, Cd, Ce, Ni, or Fe; alloy composed of metal (Me); oxide of metal (Me) (MeO x ); and a composite of metal (Me) and carbon. The negative electrode active material may be contained in an amount of 60 wt % to 98 wt %, more preferably 70 wt % to 98 wt %, based on the total weight of the solids excluding the solvent in the negative electrode slurry.

[0199] The binder is a component that helps to bind the active material to the conductive material and to the current collector, and is generally added in an amount of 1% to 30% by weight based on the total weight of the mixture containing the electrode active material. Examples of such binders may include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, various copolymers, etc.

[0200] The solvent may include an organic solvent such as N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone, dimethylacetamide, or water, and these solvents may be used alone or in a mixture of two or more thereof. By considering the coating thickness and preparation yield of the slurry, as long as the solvent used can dissolve and disperse the electrode active material, the binder, and the conductive material, the amount of the solvent is sufficient.

[0201] The viscosity modifier may be carboxymethyl cellulose, polyacrylic acid, or the like, and by adding the same, the viscosity of the electrode slurry may be adjusted to facilitate the preparation of the electrode slurry and the application process on the electrode current collector.

[0202] A filler is optionally used as a component for suppressing electrode expansion, and the filler is not particularly limited as long as it is a fiber material that does not cause chemical changes to the battery, for example, olefin polymers such as polyethylene and polypropylene; fiber materials such as glass fiber and carbon fiber are used.

[0203] If the electrode slurry composition is a positive electrode slurry composition for forming a positive electrode, the positive electrode slurry composition can be applied to a positive electrode current collector, and then dried and rolled to produce a positive electrode. Alternatively, the positive electrode can also be produced by casting the positive electrode slurry on a separate support, peeling it from the support to obtain a film, and laminating it on a positive electrode current collector.

[0204] The thickness of the positive electrode active material layer formed of the positive electrode slurry may vary depending on the loading amount, loading speed, etc. of applying the positive electrode slurry.

[0205] The thickness of the positive electrode current collector is generally 3 μm to 500 μm. There is no particular limitation on the positive electrode current collector as long as it has high conductivity and does not cause chemical changes in the relevant battery. For example, stainless steel; aluminum; nickel; titanium; sintered carbon; or aluminum or stainless steel whose surface is treated with carbon, nickel, titanium, silver, etc. can be used. In addition, the positive electrode current collector may be formed with small irregularities on its surface to enhance the binding force with the positive electrode active material, and may be formed in various forms (such as films, sheets, foils, meshes, porous bodies, foams, non-woven fabrics, etc.).

[0206] If the electrode slurry composition is a negative electrode slurry composition for forming a negative electrode, the negative electrode can be manufactured by applying the negative electrode slurry composition to a negative electrode current collector, followed by drying and roll pressing. Alternatively, the negative electrode can also be manufactured by casting the negative electrode slurry on a separate support, peeling it from the support to obtain a film, and laminating it on the negative electrode current collector.

[0207] The thickness of the negative electrode active material layer formed of the negative electrode slurry may vary depending on the loading amount, loading speed, etc. of applying the negative electrode slurry.

[0208] The thickness of the negative electrode current collector is generally 3 μm to 500 μm. The negative electrode current collector is not particularly limited as long as it has high conductivity and does not cause chemical changes in the relevant battery. For example, copper; stainless steel; aluminum; nickel; titanium; sintered carbon; or copper or stainless steel whose surface is treated with carbon, nickel, titanium, silver, etc.; or aluminum-cadmium alloy can be used. In addition, like the positive electrode current collector, the negative electrode current collector can be formed with small irregularities on its surface to enhance the bonding force with the negative electrode active material, and can be formed in various forms (such as films, sheets, foils, meshes, porous bodies, foams, non-woven fabrics, etc.).

[0209] lithium secondary batteries

[0210] The lithium secondary battery includes a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte solution. Since the positive electrode and the negative electrode are the same as those described above, their detailed description is omitted.

[0211] The separator separates the negative electrode and the positive electrode and provides a channel for the movement of lithium ions. The separator can be used without any particular restriction, as long as it is commonly used as a separator in a lithium secondary battery. As a separator, it is particularly preferred to have low resistance to the movement of electrolyte ions and excellent electrolyte solution impregnation ability. Specifically, a porous polymer film can be used, for example, a porous polymer film made of a polyolefin-based polymer such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, ethylene / methacrylate copolymer, etc., or a laminated structure of two or more layers thereof. In addition, conventional porous non-woven fabrics can also be used, for example, non-woven fabrics made of high melting point glass fiber, polyethylene terephthalate fiber, etc. In addition, a coated separator comprising a ceramic component or a polymer material can be used to ensure heat resistance or mechanical strength, and the separator can be selectively used with a single layer or multilayer structure.

[0212] The electrolyte may include, but is not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel polymer electrolytes, solid inorganic electrolytes, and melt inorganic electrolytes that can be used to manufacture lithium secondary batteries. Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0213] The organic solvent may be used without any particular limitation, as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent may be an ester-based solvent such as methyl acetate, ethyl acetate, γ-butyrolactone or ε-caprolactone; an ether-based solvent such as dibutyl ether or tetrahydrofuran; a ketone-based solvent such as cyclohexanone; an aromatic hydrocarbon-based solvent such as benzene or fluorobenzene; a carbonate-based solvent such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC) or propylene carbonate (PC); an alcohol-based solvent such as ethanol or isopropanol; a nitrile such as R-CN (R is a C2 to C20 linear, branched or cyclic hydrocarbon group, and may include a double bond aromatic ring or an ether bond); an amide such as dimethylformamide; a dioxolane such as 1,3-dioxolane; or sulfolane. Among them, carbonate-based solvents are preferred, and a mixture of cyclic carbonates (e.g., ethylene carbonate or propylene carbonate, etc.) with high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery and a compound based on linear carbonates (e.g., ethyl methyl carbonate, dimethyl carbonate or diethyl carbonate, etc.) with low viscosity is more preferred. In this case, when cyclic carbonates and chain carbonates are mixed in a volume ratio of about 1:1 to about 1:9, the performance of the electrolyte can be excellent.

[0214] Lithium salts can be used without particular limitation, as long as they are compounds that can provide lithium ions used in lithium secondary batteries. Specifically, the lithium salt can be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI or LiB(C2O4)2. The concentration of the lithium salt is preferably used in the range of 0.1M to 2.0M. If the concentration of the lithium salt is within the above range, since the electrolyte has appropriate conductivity and viscosity, it can exhibit excellent electrolyte performance and lithium ions can be effectively moved.

[0215] In the electrolyte, in addition to the above-mentioned electrolyte components, for the purpose of improving the life characteristics of the battery, suppressing the reduction of the battery capacity, and improving the discharge capacity of the battery, for example, one or more additives may be contained, for example, a halogenated alkylene carbonate-based compound such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted Oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol or aluminum trichloride. In this case, the additive may be included in an amount of 0.1 wt % to 5 wt % based on the total weight of the electrolyte.

[0216] A lithium secondary battery comprising an electrode manufactured using the carbon nanotube dispersion according to the present invention, specifically a lithium secondary battery comprising a negative electrode manufactured using the carbon nanotube dispersion, can stably exhibit excellent discharge capacity and output characteristics because the carbon nanotubes are uniformly dispersed within the negative electrode and the content of the carbon nanotubes can be reduced compared to a case where a conductive material such as conventional carbon black is included. Therefore, it can be used in the fields of portable devices (such as mobile phones, laptops, and digital cameras) and electric vehicles (such as hybrid electric vehicles (HEVs)).

[0217] Therefore, according to another embodiment of the present invention, a battery module including a lithium secondary battery as a unit battery and a battery pack including the same may be provided.

[0218] The battery module or battery pack can be used as a power source for any one or more of the following medium and large-sized devices: power tools; electric vehicles, including electric vehicles (EV), hybrid electric vehicles and plug-in hybrid electric vehicles (PHEV); or power storage systems; etc.

[0219] Embodiments of the invention

[0220] Hereinafter, specific embodiments of the present invention are presented. However, the embodiments described below are only used to specifically illustrate or explain the present invention, and the present invention is not limited thereto. In addition, since those skilled in the art can fully infer the contents not described herein technically, their descriptions are omitted.

[0221] Example

[0222] Example 1

[0223] (1) 4.5 g (0.9 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion) of polyvinylpyrrolidone (PVP) (PVP K15, manufactured by Zhangzhou Huafu Chemical company) as a first dispersant containing nitrogen atoms, 1.5 g (0.3 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion) of Direct Red 80 (Sigma Aldrich) as a second dispersant containing a compound represented by Formula 1, and 490 g of water as a solvent were mixed to prepare 496 g of a mixed solution, and the mixed solution was put into a dissolving tank (dissolver, Dispermat-CA, manufactured by VMA-GETZMANN company) equipped with an impeller and a container, and mixed by stirring at 400 rpm for 10 minutes.

[0224] To the above mixture was further added 4.0 g (0.8 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion) of a 1,160 m 2 / g specific surface area and an average particle size of 5 μm (D 50 ) and stirred the mixture at 8,000 rpm for 60 minutes to prepare a primary dispersion of 500 g of carbon nanotubes in total.

[0225] (3) The primary dispersion of carbon nanotubes was uniformly dispersed 7 times under a pressure of 14,000 psi using a high-pressure disperser (PICOMAX, manufactured by Micronox company) to produce a secondary dispersion of carbon nanotubes.

[0226] Example 2

[0227] A carbon nanotube dispersion was prepared in the same manner as in Example 1, except that in Example 1 above, the content of the first dispersant was 4.8 g (0.96 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion), and the content of the second dispersant was 1.2 g (0.24 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion).

[0228] Example 3

[0229] A carbon nanotube dispersion was prepared in the same manner as in Example 1, except that in Example 1 above, the content of the first dispersant was 4.0 g (0.8 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion), and the content of the second dispersant was 2.0 g (0.4 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion).

[0230] Comparative Example 1

[0231] A carbon nanotube dispersion was prepared in the same manner as in Example 1, except that in Example 1 above, the content of the first dispersant was 6.0 g (1.2 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion) and no second dispersant was added.

[0232] Comparative Example 2

[0233] A carbon nanotube dispersion was prepared in the same manner as in Example 1, except that in Example 1 above, the content of the first dispersant was 3.0 g (0.6 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion), and the content of the second dispersant was 3.0 g (0.6 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion).

[0234] Comparative Example 3

[0235] A carbon nanotube dispersion was prepared in the same manner as in Example 1, except that in Example 1 above, the content of the first dispersant was 5.6 g (1.12 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion), and the content of the second dispersant was 0.4 g (0.08 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion).

[0236] Comparative Example 4

[0237] A carbon nanotube dispersion was prepared in the same manner as in Example 1, except that in Example 1 above, the content of the second dispersant was 6.0 g (1.2 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion) and the first dispersant was not added.

[0238] Comparative Example 5

[0239] A carbon nanotube dispersion was prepared in the same manner as in Example 3, except that in Example 3, the content of the first dispersant was 3.375 g (0.6 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion), and the content of tristyrylphenol ethoxylate used as the second dispersant instead of Direct Red 80 (manufactured by Sigma Aldrich company) was 1.125 g (0.225 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion).

[0240] Comparative Example 6

[0241] A carbon nanotube dispersion was prepared in the same manner as in Example 3, except that in Example 3, the content of the first dispersant was 3.375 g (0.6 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion), and the content of the styrene maleic acid copolymer used as the second dispersant instead of Direct Red 80 (manufactured by Sigma Aldrich company) was 1.125 g (0.225 parts by weight relative to a total of 100 parts by weight of the carbon nanotube dispersion).

[0242] Experimental example

[0243] The viscosities of the carbon nanotube dispersions of Examples 1 to 3 and Comparative Examples 1 to 6 were measured, and the viscosities were measured again after they were left at 25° C. for one week, and the results are shown in Table 1 below.

[0244] The viscosity was measured using a viscometer (Viscometer TV-25, rotor code 01, manufactured by TOKISANGYO company) at 25° C. and 1 rpm.

[0245] [Table 1]

[0246]

[0247] (*The contents of CNT, first dispersant, and second dispersant are based on a total of 100 parts by weight of the carbon nanotube dispersion)

[0248] (*“Ratio” is the weight ratio of the second dispersant to the first dispersant)

[0249] Referring to Table 1 above, it can be confirmed that the carbon nanotube dispersions of Examples 1 to 3, which contain a first dispersant and Direct Red 80, which is a compound represented by Formula 1 of the present invention, as a second dispersant, have low initial viscosities immediately after dispersing the carbon nanotubes in an aqueous solvent, as compared to the carbon nanotube dispersion of Comparative Example 1 containing only polyvinyl pyrrolidone as a first dispersant, and in particular, very effectively suppress an increase in the viscosity of the carbon nanotube dispersion over time.

[0250] In the case of the carbon nanotube dispersions of Comparative Examples 2 and 3, it can be seen that, compared with the carbon nanotube dispersions of Examples 1 to 3, since the second dispersant is included in excess (Comparative Example 2) or included in an amount less than a certain content (Comparative Example 3), the initial viscosity immediately after dispersing the carbon nanotubes in the aqueous solvent is high, and the effect of suppressing the increase in the viscosity of the dispersion over time is not exhibited.

[0251] In the case of the carbon nanotube dispersion of Comparative Example 4, it was confirmed that, due to the absence of the first dispersant, there was a problem in that the viscosity of the carbon nanotube dispersion increased rapidly over time compared to the carbon nanotube dispersions of Examples 1 to 3.

[0252] In the case of the carbon nanotube dispersions of Comparative Examples 5 and 6, it can be seen that, compared with the carbon nanotube dispersions of Examples 1 to 3, since the compound represented by Formula 1 according to the present invention is not used as the second dispersant, the initial viscosity immediately after the carbon nanotubes are dispersed in the aqueous solvent is high, and the effect of suppressing the increase in the viscosity of the carbon nanotube dispersion over time is not exhibited.

[0253] Therefore, it was determined that only when a carbon nanotube dispersion formed by dispersing carbon nanotubes in an aqueous solvent contained the first dispersant containing nitrogen atoms according to the present invention and the second dispersant containing the compound represented by Formula 1, and the first dispersant and the second dispersant were contained in a certain weight ratio, the carbon nanotube dispersion exhibited low viscosity and the increase in viscosity over time could be suppressed.

[0254] In the above, although the preferred embodiments of the present invention have been described in detail, 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 invention defined in the appended claims also fall within the scope of the present invention.

Claims

1. A carbon nanotube dispersion comprising: carbon nanotubes; a first dispersant containing nitrogen atoms; a second dispersant containing a compound represented by the following formula 1; and a solvent: [Formula 1] in, Ar1 and Ar6 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 aryl group, Ar2 to Ar5 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 arylene group, and L1 is an amino linkage, an ether linkage, a thiol linkage, a hydrazine linkage, a sulfinate linkage, a sulfonate linkage, a sulfonamide linkage, an ester linkage, a carbonate linkage, a carbamate linkage, an amide linkage, or a urea linkage.

2. The carbon nanotube dispersion according to claim 1, wherein Ar1 and Ar6 in Formula 1 are respectively represented by the following Formula 2, Ar2 and Ar5 in Formula 1 are respectively represented by the following Formula 3, and Ar3 and Ar4 in Formula 1 are respectively represented by the following Formula 4: [Formula 2] [Formula 3] [Formula 4] In the formula 2, R1 to R6 are the same as or different from each other and are each independently hydrogen; deuterium; halogen; cyano; sulfonate group; hydroxyl; amine; nitro; or a moiety attached to the azo group in Formula 1, provided that any one of R1 to R6 is a moiety attached to the azo group in Formula 1, In the formula 3, R7 to R12 are the same as or different from each other and are each independently hydrogen; deuterium; halogen; cyano; sulfonate group; hydroxyl; amine; nitro; or a moiety attached to the azo group in Formula 1, provided that at least two of R7 to R12 are moieties attached to the azo group in Formula 1, and In the above formula 4, R13 to R20 are the same as or different from each other and are each independently hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; nitro group; a portion connected to the azo group in Formula 1; or a portion connected to L1 in Formula 1, provided that at least any one of R13 to R20 is a portion connected to the azo group in Formula 1, and any one of the remaining portions of R13 to R20 other than the portion connected to the azo group in Formula 1 is a portion connected to L1 in Formula 1.

3. The carbon nanotube dispersion according to claim 2, wherein among R1 to R6 in Formula 2, at least one of the remaining parts excluding the part connected to the azo group in Formula 1 is a sulfonate group, among R7 to R12 in Formula 3, at least one of the remaining parts excluding the part connected to the azo group in Formula 1 is a sulfonate group, and among R13 to R20 in Formula 4, at least one of the remaining parts excluding the part connected to the azo group and L1 in Formula 1 is a sulfonate group.

4. The carbon nanotube dispersion according to claim 1, wherein the second dispersant comprises a compound represented by the following formula 1-1: [Formula 1-1] in, R1 to R5, R7 to R10, and R13 to R18 are the same as or different from each other, and are each independently hydrogen; deuterium; halogen; cyano; sulfonate; hydroxyl; amine; or nitro. 5 . The carbon nanotube dispersion according to claim 1 , wherein the carbon nanotubes are included in an amount of 0.05 parts by weight to 5 parts by weight based on 100 parts by weight of the carbon nanotube dispersion.

6. The carbon nanotube dispersion according to claim 1, wherein the carbon nanotubes have a BET specific surface area of ​​800 m 2 / g to 2,000m 2 / g.

7. The carbon nanotube dispersion according to claim 1, wherein the first dispersant is at least one selected from the group consisting of polyvinyl pyrrolidone, polyacrylic acid hydrazide, poly-N-vinyl-5-methyl Oxazolidinone, N-alkylpolyimine, N-acetylpolyimine, polyacrylamide, poly-L-lysine hydrobromide, benzyl-dodecyl-dimethylammonium chloride and polyethyleneimine. 8 . The carbon nanotube dispersion according to claim 1 , wherein the first dispersant is included in an amount of 0.01 parts by weight to 10 parts by weight based on 100 parts by weight of the carbon nanotube dispersion. 9 . The carbon nanotube dispersion according to claim 1 , wherein the second dispersant is included in an amount of 0.001 parts by weight to 9 parts by weight based on 100 parts by weight of the carbon nanotube dispersion. 10 . The carbon nanotube dispersion according to claim 1 , wherein the first dispersant and the second dispersant are included in a weight ratio of 100:10 to 100:

90. The carbon nanotube dispersion according to claim 1 , wherein the carbon nanotube dispersion has an initial viscosity of 1 to 10 Pa·s when measured at 25° C. and 1 rpm.

12. The carbon nanotube dispersion according to claim 1, wherein the carbon nanotube dispersion has a viscosity increase rate represented by the following Equation 1 of 15% or less: [Equation 1] Viscosity increase rate (%)={(viscosity measured after standing at 25° C. for 1 week−initial viscosity) / initial viscosity}×100.

13. A method for preparing the carbon nanotube dispersion according to claim 1, comprising the following steps: (1) preparing a primary dispersion of carbon nanotubes by mixing carbon nanotubes, a first dispersant containing nitrogen atoms, a second dispersant containing a compound represented by the following Formula 1, and a solvent; and (2) dispersing the primary dispersion of carbon nanotubes to prepare a secondary dispersion of carbon nanotubes: [Formula 1] in, Ar1 and Ar6 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 aryl group, Ar2 to Ar5 are the same as or different from each other and are each independently a substituted or unsubstituted C6 to C30 arylene group, and L1 is an amino linkage, an ether linkage, a thiol linkage, a hydrazine linkage, a sulfinate linkage, a sulfonate linkage, a sulfonamide linkage, an ester linkage, a carbonate linkage, a carbamate linkage, an amide linkage, or a urea linkage.

Images