Carbon nanotube dispersion and preparation method therefor

Abstract

The present invention relates to a carbon nanotube dispersion and a preparation method therefor, the carbon nanotube dispersion comprising: carbon nanotubes; a first dispersant comprising nitrogen atoms; a second dispersant comprising a compound represented by chemical formula 1; and a solvent. The details of the compound represented by chemical formula 1 are as defined in the specification.

Description

Carbon nanotube dispersion and method for producing the same

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2023-0099687, dated July 31, 2023, Korean Patent Application No. 10-2023-0099783, dated July 31, 2023, Korean Patent Application No. 10-2023-0099794, dated July 31, 2023, Korean Patent Application No. 10-2024-0100218, dated July 29, 2024, Korean Patent Application No. 10-2024-0100280, dated July 29, 2024, and Korean Patent Application No. 10-2024-0100284, dated July 29, 2024, all of which are incorporated herein by reference. Includes as part of.

[0002] The present invention relates to a carbon nanotube dispersion and a method for producing the same.

[0003] With the increasing technological development and demand for mobile devices, the demand for secondary batteries as an energy source is rapidly increasing. Among these secondary batteries, lithium secondary batteries, which boast high energy density and voltage, long cycle life, and low self-discharge rates, are commercialized and widely used. Furthermore, active research is being conducted on methods to improve electrode density and produce electrodes with higher energy density per unit volume as electrodes for these high-capacity lithium secondary batteries.

[0004] In general, high-density electrodes are formed by molding electrode active material particles having a size of several μm to several tens of μm using a high-pressure press. During the molding process, the particles may be deformed and the space between the particles may be reduced, so that the electrolyte permeability is likely to deteriorate.

[0005] To address the above issues, conductive materials with superior electrical conductivity and strength are used during electrode manufacturing. These conductive materials are positioned between the electrode active materials, and even during the molding process, they maintain micropores between the active material particles, facilitating the penetration of the electrolyte. Their superior electrical conductivity reduces electrode resistance. Among these conductive materials, carbon nanotubes, a fibrous carbon-based conductive material that can further reduce electrode resistance by forming electrically conductive paths within the electrode, are increasingly being used.

[0006] Carbon nanotubes, a type of microscopic carbon fiber, are tubular carbon fibers with a diameter of less than 1 ㎛. Their unique structure, resulting in high conductivity, tensile strength, and heat resistance, has raised expectations for practical application in various fields. However, carbon nanotubes have low dispersibility and are prone to agglomeration due to the strong van der Waals attraction between them due to their high specific surface area.

[0007] To address these issues, mechanical dispersion techniques, such as ultrasonic treatment, have been proposed to disperse carbon nanotubes in a dispersion medium. However, mechanical dispersion techniques have problems, such as carbon nanotubes agglomerating immediately after ultrasonic treatment or reagglomerating over time after dispersion.

[0008] Accordingly, there is a need to develop a method for producing 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. 2017-0129804 (May 11, 2017)

[0012] (Patent Document 2) U.S. Patent Publication No. 2014-0308194 (October 16, 2014)

[0013] (Patent Document 3) Japanese Patent Publication No. 2021-167400 (October 21, 2021)

[0014] The purpose 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 chemical formula 1, and a solvent, which has excellent dispersibility, low viscosity of the dispersion and low particle size of the dispersed particles, and little change in viscosity over time.

[0015] [Chemical Formula 1]

[0016]

[0017] In the above chemical formula 1,

[0018] Ar1 and Ar2 are each independently a substituted or unsubstituted C6 to C30 aryl group.

[0019] Another object of the present invention is to provide a method for producing the carbon nanotube dispersion.

[0020] One embodiment of the present invention provides a carbon nanotube dispersion comprising carbon nanotubes, a first dispersant including nitrogen atoms, a second dispersant including a compound represented by the following chemical formula 1, and a solvent.

[0021] [Chemical Formula 1]

[0022]

[0023] In the above chemical formula 1,

[0024] Ar1 and Ar2 are each independently a substituted or unsubstituted C6 to C30 aryl group.

[0025] Ar1 of the above chemical formula 1 may be represented by the following chemical formula 2, and Ar2 of the above chemical formula 1 may be represented by the following chemical formula 3.

[0026] [Chemical Formula 2]

[0027]

[0028] [Chemical Formula 3]

[0029]

[0030] In the above chemical formula 2, R1 to R8 are the same as or different from each other, and each independently represent hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; nitro group; substituted or unsubstituted C1 to C10 alkyl group; substituted or unsubstituted C1 to C10 alkoxy group; or a moiety connecting to chemical formula 2, wherein any one of R1 to R8 is a moiety connecting to an azo group of chemical formula 1,

[0031] In the above chemical formula 3, R9 to R14 are the same as or different from each other, and each independently represent hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; nitro group; substituted or unsubstituted C1 to C10 alkyl group; substituted or unsubstituted C1 to C10 alkoxy group; or a moiety connecting to chemical formula 3, wherein any one of R9 to R14 is a moiety connecting to an azo group of chemical formula 1.

[0032] The second dispersant may include a compound represented by any one of the following chemical formulae 1-1a to 1-1c.

[0033] [Chemical Formula 1-1a]

[0034]

[0035] In the above chemical formula 1-1a,

[0036] R1 to R7 are the same or different and are each independently hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; nitro group; substituted or unsubstituted C1 to C10 alkyl group; or substituted or unsubstituted C1 to C10 alkoxy group,

[0037] R9 to R13 are the same or different and are each independently hydrogen; deuterium; halogen; cyano group; sulfonate group; amine group; nitro group; or a substituted or unsubstituted C1 to C10 alkoxy group;

[0038] [Chemical Formula 1-1b]

[0039]

[0040] In the above chemical formula 1-1b,

[0041] R1 to R7, R9 to R15 are the same or different, and each independently represent hydrogen; deuterium; halogen; cyano group; sulfonate group; or hydroxyl group;

[0042] [Chemical Formula 1-1c]

[0043]

[0044] In the above chemical formula 1-1c,

[0045] R1 to R5 are the same or different and are each independently hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; nitro group; or NRaRb, wherein at least one of R1 to R5 is represented by NRaRb, Ra and Rb are the same or different and are each independently hydrogen; deuterium; or a substituted or unsubstituted C1 to C10 alkyl group,

[0046] R6 to R10 are the same or different, and each independently represent hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; or nitro group, provided that at least one of R6 to R10 is a sulfonate group.

[0047] The carbon nanotubes may be included in an amount of 0.05 to 5 parts by weight based on 100 parts by weight of the above carbon nanotube dispersion.

[0048] The BET surface area of ​​the above carbon nanotubes is 800 to 2,000 m 2 / g may be.

[0049] The first dispersant may be at least one selected from the group consisting of polyvinylpyrrolidone, polyacrylic acid hydrazide, poly-N-vinyl-5-methoxazolidon, N-alkyl polyimine, N-acetyl polyimine, polyacrylamide, poly-L-lysine hydrobromide, benzyl-dodecyl-dimethylammonium chloride, and polyethylenimine.

[0050] 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.

[0051] 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.

[0052] The first dispersant and the second dispersant may be included in a weight ratio of 100:10 to 100:90.

[0053] The above carbon nanotube dispersion may have an initial viscosity of 1 to 8 Pa·s measured at 25°C and 1 rpm.

[0054] The above carbon nanotube dispersion may have a viscosity increase rate of 15% or less, as expressed by the following equation (1).

[0055] [Formula 1]

[0056] Viscosity increase rate (%) = {(Viscosity measured after leaving at 25℃ for 1 week - Initial viscosity) / Initial viscosity} × 100

[0057] Another embodiment of the present invention provides a method for producing a carbon nanotube dispersion, comprising the steps of (1) preparing a carbon nanotube primary dispersion by mixing carbon nanotubes, a first dispersant containing nitrogen atoms, a second dispersant containing a compound represented by the above chemical formula 1, and a solvent, and (2) preparing a carbon nanotube secondary dispersion by dispersing the carbon nanotube primary dispersion.

[0058] The carbon nanotube dispersion according to the present invention uses a first dispersant containing a nitrogen atom and a second dispersant containing a compound represented by the above chemical formula 1, so that despite using carbon nanotubes having a large specific surface area, the viscosity of the dispersion exhibits a small change over time, exhibits a relatively low viscosity, and has the characteristics of having a small particle size of dispersed particles by uniformly and effectively dispersing the carbon nanotubes.

[0059] Hereinafter, embodiments of the present invention will be described in detail. Prior to this, terms and words used in this specification and claims should not be interpreted as limited to their conventional or dictionary meanings. Rather, they should be interpreted with meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of a term to best explain his or her invention. Accordingly, the configurations described in the embodiments described in this specification are merely the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

[0060] In this specification, the term "substitution" means that a hydrogen atom bonded to a carbon atom of a compound is replaced with another substituent, and the position of substitution is not limited as long as it is a position where a hydrogen atom is replaced, i.e., a position where a substituent can be replaced, and when two or more are replaced, the two or more substituents may be the same or different from each other.

[0061] In this specification, "substituted or unsubstituted" means deuterium; halogen; cyano group; straight or branched chain alkyl group having 1 to 60 carbon atoms; straight or branched chain alkenyl group having 2 to 60 carbon atoms; straight or branched chain alkynyl group having 2 to 60 carbon atoms; monocyclic or polycyclic cycloalkyl group having 3 to 60 carbon atoms; monocyclic or polycyclic heterocycloalkyl group having 2 to 60 carbon atoms; monocyclic or polycyclic aryl group having 6 to 60 carbon atoms; monocyclic or polycyclic heteroaryl group having 2 to 60 carbon atoms; -SiRR'R"; -P(=O)RR'; C1 to C20 alkylamine group; C6 to C60 monocyclic or polycyclic arylamine group; and C2 to C60 monocyclic or polycyclic heteroarylamine group, which is substituted or unsubstituted with one or more substituents selected from the group consisting of a C1 to C20 alkylamine group; a C6 to C60 monocyclic or polycyclic arylamine group; and a C2 to C60 monocyclic or polycyclic heteroarylamine group, or substituted or unsubstituted with a substituent in which two or more substituents selected from the above-mentioned substituents are connected.

[0062] Throughout this specification, whenever a part is said to 'include' a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0063] Throughout this specification, “%” means weight percent unless explicitly stated otherwise.

[0064] In this specification, the average particle size "D 50 " means the particle size corresponding to 50% of the volume accumulation. The above D 50 For example, it can be measured using the laser diffraction method. The laser diffraction method can generally measure particle sizes from the submicron range to several mm, and can obtain results with high reproducibility and high resolution.

[0065] In this specification, the “specific surface area” is measured by the BET method (Brunauer-Emmett-Teller Analysis), and specifically, can be calculated from the nitrogen gas adsorption amount at liquid nitrogen temperature (77 K) using BELSORP-mino II of BEL Japan.

[0066]

[0067] carbon nanotube dispersion

[0068] The carbon nanotube dispersion according to the present invention comprises carbon nanotubes, a first dispersant containing nitrogen atoms, a second dispersant containing a compound represented by the above chemical formula 1, and a solvent. Hereinafter, each component of the carbon nanotube dispersion of the present invention will be described in detail.

[0069]

[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 in a bundle shape, in whole or in part, wherein the carbon nanotube units have a graphite sheet in the shape of a cylinder with a nano-sized diameter, and sp 2 It has a bonding structure. At this time, depending on the angle and structure at which the graphite plane is rolled, it can exhibit the characteristics of a conductor or a semiconductor. The carbon nanotube unit can be classified into single-walled carbon nanotube (SWCNT, single-walled carbon nanotube), double-walled carbon nanotube (DWCNT, double-walled carbon nanotube), and multi-walled carbon nanotube (MWCNT, multi-walled carbon nanotube) depending on the number of bonds forming the wall.

[0072] The term 'bundle type' used in the present invention, unless otherwise stated, 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 their longitudinal axes substantially in the same orientation, or are arranged and then twisted or entangled. The term 'non-bundle type or entangled type' refers to a shape in which carbon nanotube units are entangled without a definite shape such as a bundle or rope.

[0073] Carbon nanotubes are highly conductive, but they tend to aggregate due to the van der Waals forces that exist between them. When the conductive material aggregates, it cannot properly form a conductive path within the electrode. Furthermore, increasing the amount of conductive material required to increase conductivity leads to a relatively small amount of active material, which can actually reduce electrode performance, such as capacity. Consequently, commercializing carbon nanotubes as a conductive material has been challenging.

[0074] The carbon nanotube dispersion according to the present invention includes a first dispersant containing a nitrogen atom and a second dispersant containing a compound represented by the above chemical formula 1, so that the initial viscosity of the carbon nanotube dispersion can be significantly reduced, and the occurrence of viscosity changes over time can be suppressed, while maintaining a low particle size of the dispersed particles.

[0075] A carbon nanotube dispersion according to one embodiment of the present invention may include, but is not limited to, any one or more of single-walled, double-walled, and multi-walled carbon nanotubes as the carbon nanotubes, and specifically may include single-walled carbon nanotubes. Since the 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] Meanwhile, the average diameter of the carbon nanotube may be, for example, 0.6 to 10 nm, preferably 0.8 to 5 nm, more preferably 0.8 to 3 nm, and may be 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 may be 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 to 20 μm, preferably 1 to 20 μm, more preferably 5 to 20 μm, and may be 5 μm or more, 7 μm or more, 9 μm or more, 11 μm or more, or 13 μm or more, and may be 20 μm or less, 18 μm or less, 16 μm or less, or 14 μm or less. When the average diameter and average length of the carbon nanotubes satisfy the above ranges, it is effective in reducing the viscosity of the dispersion and improving the storage stability, and excellent cycle characteristics can be realized even when applied to an electrode active material.

[0078] At this time, 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 carbon nanotubes may be included in an amount of 0.05 to 5 parts by weight based on 100 parts by weight of the entire carbon nanotube dispersion, and may be 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. It may be 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. When the content of carbon nanotubes satisfies the above range, the effect of improving the viscosity of the dispersion and the effect of improving the conductivity of the secondary battery manufactured through the carbon nanotube dispersion are excellent.

[0080] The BET surface area of ​​the above carbon nanotubes is 800 m 2 / g to 2,000 m 2 / g can be, for example, 800 m 2 / g or more, 810 m 2 / g or more, 820 m 2 / g or more, 830 m 2 / g or more, 840 m2 / g or more, 850 m 2 / g or more, 860 m 2 / g or more, 870 m 2 / g or more, 880 m 2 / g or more, 890 m 2 / g or more, 900 m 2 / g or more, 910 m 2 / g or more, 920 m 2 / g or more, 930 m 2 / g or more, 940 m 2 / g or more, 950 m 2 / g or more, 960 m 2 / g or more, 970 m 2 / g or more, 980 m 2 / g or more, 990 m 2 / g or more, 1,000 m 2 / g or more, 1,010 m 2 / g or more, 1,020 m 2 / g or more, 1,030 m 2 / g or more, 1,040 m 2 / g or more, 1,050 m 2 / g or more, 1,060 m 2 / g or more, 1,070 m 2 / g or more, 1,080 m 2 / g or more, 1,090 m 2 / g or more, 1,100 m 2 / g or more, 1,110 m 2 / g or more, 1,120 m 2 / g or more, 1,130 m 2 / g or more, 1,140 m 2 / g or more, 1,150 m 2 / g or more, 1,160 m 2 / g or more, 1,170 m 2 / g or more, 1,180 m 2 / g or more, 1,190 m 2 / g or more, 1,200 m 2 / g or more, 1,210 m 2 / g or more, 1,220 m2 / g or more, 1,230 m 2 / g or more, 1,240 m 2 / g or more, 1,250 m 2 / g or more, 1,260 m 2 / g or more, 1,270 m 2 / g or more, 1,280 m 2 / g or more, 1,290 m 2 / g or more, 1,300 m 2 / g or more, 1,310 m 2 / g or more, 1,320 m 2 / g or more, 1,330 m 2 / g or more, 1,340 m 2 / g or more, 1,350 m 2 / g or more, 1,360 m 2 / g or more, 1,370 m 2 / g or more, 1,380 m 2 / g or more, 1,390 m 2 / g or more or 1,400 m 2 / g can be more than 2,000 m 2 / g or less, 1,990 m 2 / g or less, 1,980 m 2 / g or less, 1,970 m 2 / g or less, 1,960 m 2 / g or less, 1,950 m 2 / g or less, 1,940 m 2 / g or less, 1,930 m 2 / g or less, 1,920 m 2 / g or less, 1,910 m 2 / g or less, 1,900 m 2 / g or less, 1,890 m 2 / g or less, 1,880 m 2 / g or less, 1,870 m 2 / g or less, 1,860 m 2 / g or less, 1,850 m 2 / g or less, 1,840 m 2 / g or less, 1,830 m 2 / g or less, 1,820 m 2 / g or less, 1,810 m 2 / g or less, 1,800 m 2 / g or less, 1,790 m 2 / g or less, 1,780 m 2 / g or less, 1,770 m 2 / g or less, 1,760 m 2 / g or less, 1,750 m 2 / g or less, 1,740 m 2 / g or less, 1,730 m 2 / g or less, 1,720 m 2 / g or less, 1,710 m 2 / g or less, 1,700 m 2 / g or less, 1,690 m 2 / g or less, 1,680 m 2 / g or less, 1,670 m 2 / g or less, 1,660 m 2 / g or less, 1,650 m 2 / g or less, 1,640 m 2 / g or less, 1,630 m 2 / g or less, 1,620 m 2 / g or less, 1,610 m 2 / g or less, 1,600 m 2 / g or less, 1,590 m 2 / g or less, 1,580 m 2 / g or less, 1,570 m 2 / g or less, 1,560 m 2 / g or less, 1,550 m 2 / g or less, 1,540 m 2 / g or less, 1,530 m 2 / g or less, 1,520 m 2 / g or less, 1,510 m 2 / g or less, 1,500 m 2 / g or less, 1,490 m 2 / g or less, 1,480 m 2 / g or less, 1,470 m 2 / g or less, 1,460 m 2 / g or less, 1,450 m 2 / g or less, 1,440 m 2 / g or less, 1,430 m 2 / g or less, 1,420 m 2 / g or less or 1,410 m 2 / g or less. When carbon nanotubes having a high BET surface area as described above are used, the 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 uniformly dispersed. When a carbon nanotube dispersion having a low carbon nanotube content is used in the production of an electrode slurry, the solid content of the produced electrode slurry decreases, so that the thickness (wet thickness) before applying and drying the electrode slurry becomes thick, and the rolling ratio measured after subsequent drying and rolling treatment increases, so that the difference in the thickness ratio before and after drying and rolling becomes large. In this way, if the rolling ratio increases, the compositions inside the slurry, including the positive electrode active material, may be damaged during the process, which may cause a problem of deterioration in the performance of the battery.

[0082]

[0083] (2) Dispersant

[0084] The carbon nanotube dispersion according to the present invention includes a dispersant to improve the dispersibility of the carbon nanotubes, and includes a first dispersant including a nitrogen atom as the dispersant and a second dispersant including a compound represented by the following chemical formula 1.

[0085] [Chemical Formula 1]

[0086]

[0087] In the above chemical formula 1,

[0088] Ar1 and Ar2 are each independently a substituted or unsubstituted C6 to C30 aryl group.

[0089] In the above carbon nanotube dispersion, the first dispersant and the second dispersant serve to increase the dispersibility of the carbon nanotubes so that the carbon nanotubes can be evenly dispersed without agglomeration in the dispersion, and in particular, serve to suppress changes in the viscosity of the carbon nanotube dispersion over time and to lower the average particle size of the dispersed particles.

[0090] In a carbon nanotube dispersion according to one specific example of the present invention, the first dispersant containing the nitrogen atom may be one that can be dissolved in an aqueous solvent to be described later, and may be, for example, at least one selected from the group consisting of polyvinylpyrrolidone, polyacrylic acid hydrazide, poly-N-vinyl-5-methoxazolidon, N-alkyl polyimine, N-acetyl polyimine, polyacrylamide, poly-L-lysine hydrobromide, benzyl-dodecyl-dimethylammonium chloride, and polyethylenimine, and preferably Polyvinylpyrrolidone can be used. According to one specific example of the present invention, the carbon nanotube dispersion can exhibit an effect of improving the viscosity of the dispersion and an effect of suppressing changes in viscosity over time by including the first dispersing agent containing the nitrogen atom.

[0091] In one specific example 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, 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, 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 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.It may contain 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.

[0092] 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, the content of the dispersant is insufficient, so that a sufficient dispersing effect is not achieved, and thus the viscosity of the dispersion is not formed low, and there may be a problem in that the viscosity increases over time. If it exceeds 10 parts by weight, the content of the first dispersant is excessive, so that coagulation between solids in the dispersion progresses, and there may be a problem in that the viscosity of the dispersion is formed high.

[0093] In addition, the carbon nanotube dispersion according to one embodiment of the present invention includes, in addition to the first dispersant, a second dispersant including a compound represented by the following chemical formula 1 to solve the problem that the viscosity of the dispersion increases as the content of carbon nanotubes increases in the carbon nanotube dispersion containing only the first dispersant, and thus, compared to a carbon nanotube dispersion using only a conventional dispersant, the dispersion has excellent dispersibility, and can exhibit the effects of less particle agglomeration of the slurry composition and a low sedimentation rate.

[0094] [Chemical Formula 1]

[0095]

[0096] In the above chemical formula 1,

[0097] Ar1 and Ar2 are each independently a substituted or unsubstituted C6 to C30 aryl group.

[0098] In one specific example of the present invention, Ar1 of the chemical formula 1 may be a substituted or unsubstituted C6 to C30 aryl group.

[0099] In one specific example of the present invention, Ar1 of the chemical formula 1 may be a substituted or unsubstituted C6 to C20 aryl group.

[0100] In one specific example of the present invention, Ar1 of the chemical formula 1 may be a substituted or unsubstituted C6 to C10 aryl group.

[0101] In one specific example of the present invention, Ar1 of the chemical formula 1 may be a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthalene group.

[0102] In one specific example of the present invention, Ar2 of the chemical formula 1 may be a substituted or unsubstituted C6 to C30 aryl group.

[0103] In one specific example of the present invention, Ar2 of the chemical formula 1 may be a substituted or unsubstituted C6 to C20 aryl group.

[0104] In one specific example of the present invention, Ar2 of the chemical formula 1 may be a substituted or unsubstituted C6 to C10 aryl group.

[0105] In one specific example of the present invention, Ar2 of the chemical formula 1 may be a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthalene group.

[0106] In addition, in one specific example of the present invention, Ar1 and Ar2 of the chemical formula 1 may be represented by the following chemical formula 2 or chemical formula 3, respectively.

[0107] [Chemical Formula 2]

[0108]

[0109] [Chemical Formula 3]

[0110]

[0111] In the above chemical formula 2, R1 to R8 are the same as or different from each other, and each independently represent hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; nitro group; substituted or unsubstituted C1 to C10 alkyl group; substituted or unsubstituted C1 to C10 alkoxy group; or a moiety connecting to chemical formula 2, wherein any one of R1 to R8 may be a moiety connecting to an azo group of chemical formula 1.

[0112] In the above chemical formula 3, R9 to R14 are the same as or different from each other, and each independently represent hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; nitro group; substituted or unsubstituted C1 to C10 alkyl group; substituted or unsubstituted C1 to C10 alkoxy group; or a moiety connecting to chemical formula 3, wherein any one of R9 to R14 may be a moiety connecting to an azo group of chemical formula 1.

[0113] In one specific embodiment of the present invention, R1 to R8 of the above chemical formula 2 are the same as or different from each other, and each independently represent hydrogen; deuterium; a sulfonate group; a hydroxyl group; a nitro group; a substituted or unsubstituted C1 to C5 alkyl group; a substituted or unsubstituted C1 to C5 alkoxy group; or a moiety connecting to the chemical formula 2, wherein any one of the R1 to R8 may be a moiety connecting to an azo group of the chemical formula 1.

[0114] In one specific embodiment of the present invention, R9 to R14 of the above chemical formula 3 are the same as or different from each other, and each independently represent hydrogen; deuterium; a sulfonate group; a hydroxyl group; a nitro group; a substituted or unsubstituted C1 to C5 alkyl group; a substituted or unsubstituted C1 to C5 alkoxy group; or a moiety connecting to the chemical formula 3, wherein any one of the R9 to R14 may be a moiety connecting to an azo group of the chemical formula 1.

[0115] In one specific example of the present invention, excluding the part connected to the azo group of Chemical Formula 1 among R1 to R14, at least one sulfonate group, a hydroxyl group, and a nitro group may be included.

[0116] In one specific example of the present invention, the second dispersant may include a compound represented by any one of the following chemical formulae 1-1a to 1-1c.

[0117] [Chemical Formula 1-1a]

[0118]

[0119] In the above chemical formula 1-1a,

[0120] R1 to R7 are the same or different and are each independently hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; nitro group; substituted or unsubstituted C1 to C10 alkyl group; or substituted or unsubstituted C1 to C10 alkoxy group,

[0121] R9 to R13 are the same or different and are each independently hydrogen; deuterium; halogen; cyano group; sulfonate group; amine group; nitro group; or a substituted or unsubstituted C1 to C10 alkoxy group;

[0122] [Chemical Formula 1-1b]

[0123]

[0124] In the above chemical formula 1-1b,

[0125] R1 to R7, R9 to R15 are the same or different, and each independently represent hydrogen; deuterium; halogen; cyano group; sulfonate group; or hydroxyl group;

[0126] [Chemical Formula 1-1c]

[0127]

[0128] In the above chemical formula 1-1c,

[0129] R1 to R5 are the same or different and are each independently hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; nitro group; or NRaRb, wherein at least one of R1 to R5 is represented by NRaRb, Ra and Rb are the same or different and are each independently hydrogen; deuterium; or a substituted or unsubstituted C1 to C10 alkyl group,

[0130] R6 to R10 are the same or different, and each independently represent hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; or nitro group, provided that at least one of R6 to R10 is a sulfonate group.

[0131] In one specific example of the present invention, R1 to R7 of the above chemical formula 1-1a are the same as or different from each other, and may each independently be hydrogen; a sulfonate group; or a hydroxyl group.

[0132] In one specific example of the present invention, R9 to R13 of the above chemical formula 1-1a are the same as or different from each other, and may each independently be hydrogen or a nitro group.

[0133] In one specific example of the present invention, in the chemical formulae 2 and 3, when R1 to R14 are sulfonate groups, 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.

[0134] In one specific example of the present invention, when the second dispersant is a compound represented by Chemical Formula 1-1a, it may be at least one selected from the group consisting of Nitrazine yellow, Acid orange 7, Allura Red AC, and Sunset Yellow FCF, and for example, Nitrazine yellow may be used as the second dispersant.

[0135] In a carbon nanotube dispersion according to one specific example of the present invention, the second dispersant represented by the chemical formula 1-1a includes at least one hydroxyl group and one nitro group, thereby forming a hydrogen bond with the solvent in the dispersion, thereby allowing the 'carbon nanotube-dispersant' complex to remain stably dispersed in the solvent.

[0136] In addition, in the carbon nanotube dispersion according to one specific example of the present invention, since the second dispersant represented by the chemical formula 1-1a includes at least one sulfonate group, when the dispersant is ionized upon dissolution in a solvent, an electrostatic repulsion is formed between sulfonate anions, thereby preventing aggregation between adjacent dispersants, thereby allowing the 'carbon nanotube-dispersant' complex to stably maintain a dispersed state in the solvent.

[0137] In one specific example of the present invention, R1 to R7 and R9 to R15 of the chemical formula 1-1b are the same as or different from each other, and may each independently be hydrogen; a sulfonate group; or a hydroxyl group.

[0138] In one specific example of the present invention, R1 to R7 of the chemical formula 1-1b may include at least one sulfonate group and at least one hydroxyl group.

[0139] In one specific example of the present invention, R9 to R15 of the chemical formula 1-1b may include at least one sulfonate group and at least one hydroxyl group.

[0140] In one specific example of the present invention, R1 to R7 and R9 to R15 of the chemical formula 1-1b may include at least three sulfonate groups and at least two hydroxyl groups.

[0141] In one specific example of the present invention, when the second dispersant is a compound represented by Chemical Formula 1-1b, it may include a compound represented by Chemical Formula 4 below (Hydroxynaphthol Blue).

[0142] [Chemical Formula 4]

[0143]

[0144] The second dispersant represented by the above chemical formula 1-1b forms a hydrogen bond with the solvent in the dispersion as the compound contains a hydroxyl group, thereby allowing the 'carbon nanotube-dispersant' complex to maintain a stable dispersed state in the solvent, and since it contains three or more sulfonate groups, when the dispersant is dissolved in the solvent, an electrostatic repulsion is formed between sulfonate anions as the dispersant is ionized, thereby preventing aggregation between adjacent dispersants, thereby allowing the 'carbon nanotube-dispersant' complex to maintain a stable dispersed state in the solvent.

[0145] In one specific example of the present invention, R1 to R5 of the above chemical formula 1-1c are the same as or different from each other, and each independently represent hydrogen; a sulfonate group; a hydroxyl group; or NRaRb, wherein at least one of R1 to R5 is represented by NRaRb, and Ra and Rb are the same as or different from each other, and each independently represent hydrogen; deuterium; or a substituted or unsubstituted C1 to C5 alkyl group.

[0146] In one specific example of the present invention, R1 to R5 of the above chemical formula 1-1c are the same as or different from each other, and each independently represent hydrogen; a sulfonate group; a hydroxyl group; or NRaRb, wherein at least one of R1 to R5 is represented by NRaRb, and Ra and Rb are the same as or different from each other, and each independently represent hydrogen; deuterium; or a substituted or unsubstituted C1 to C3 alkyl group.

[0147] In one specific example of the present invention, R1 to R5 of the above chemical formula 1-1c are the same as or different from each other, and are each independently represented by hydrogen; or NRaRb, wherein at least one of R1 to R5 is represented by NRaRb, and both Ra and Rb can be methyl groups.

[0148] In one specific example of the present invention, R6 to R10 of the above chemical formula 1-1c are the same as or different from each other, and are each independently hydrogen; deuterium; a sulfonate group; or a hydroxyl group, and at least one of R6 to R10 may be a sulfonate group.

[0149] In one specific example of the present invention, R6 to R10 of the above chemical formula 1-1c are the same as or different from each other, and may each independently be hydrogen or a sulfonate group.

[0150] In one specific example of the present invention, when the second dispersant is a compound represented by Chemical Formula 1-1c, it may include a compound represented by Chemical Formula 5 below (Methyl Orange).

[0151] [Chemical Formula 5]

[0152]

[0153] In a carbon nanotube dispersion according to one specific example of the present invention, since the second dispersant represented by the chemical formula 1-1c includes at least one sulfonate group, when the dispersant is ionized upon dissolution in a solvent, an electrostatic repulsion is formed between sulfonate anions, thereby preventing aggregation between adjacent dispersants, thereby allowing the 'carbon nanotube-dispersant' complex to remain stably dispersed in the solvent.

[0154] In addition, since the compound represented by the chemical formula 1-1c included in the second dispersant contains an amine group, the dispersibility with a solvent is improved by the unshared electron pair of the nitrogen atom in the amine group, and in particular, if the compound of the second dispersant represented by the chemical formula 1-1c contains a tertiary amine group, a bulky substituent is introduced, thereby preventing aggregation between dispersants, thereby increasing the dispersion efficiency of carbon nanotubes.

[0155] Since the second dispersant represented by the above chemical formula 1 contains two different aryl groups that are connected to each other by an azo group, it stably generates a π-π interaction with the carbon nanotube in a local area, thereby sufficiently enhancing the bonding strength between the dispersant and the carbon nanotube, and reduces the content of the excess dispersant that is not effectively adsorbed on the surface of the carbon nanotube, thereby preventing aggregation of the remaining dispersants.

[0156] If the carbon nanotube dispersion does not include the second dispersant according to the present invention, the area where the surface of the carbon nanotube is not sufficiently covered by the dispersant may increase, and as a result, a strong bonding force greater than an appropriate level may be generated between the carbon nanotubes, resulting in agglomeration of the carbon nanotubes, and thus a high viscosity of the dispersion may be formed.

[0157] In addition, when the second dispersant contains, for example, three or more aromatic rings in its molecular structure, the molecules form a linear, angular, or densely packed structure, which is disadvantageous for surface adsorption of small-diameter carbon nanotubes, particularly single-walled carbon nanotubes. In addition, strong π-π interactions occur between non-adsorbed dispersants, which intensifies the aggregation of the dispersants, thereby forming a high viscosity of the dispersion, and the viscosity of the dispersion may increase significantly over time.

[0158] In one specific example 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, 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, 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 More than 2.4 parts by weight, more than 2.5 parts by weight, more than 2.6 parts by weight, more than 2.7 parts by weight, more than 2.8 parts by weight, more than 2.9 parts by weight, more than 3 parts by weight, more than 3.1 parts by weight, more than 3.2 parts by weight, more than 3.3 parts by weight, more than 3.4 parts by weight, more than 3.5 parts by weight, more than 3.6 parts by weight, more than 3.7 parts by weight, more than 3.8 parts by weight, more than 3.9 parts by weight, more than 4 parts by weight, more than 4.1 parts by weight, more than 4.2 parts by weight, more than 4.3 parts by weight, more than 4.4 parts by weight or more than 4.5 parts by weight, and may contain less than 9 parts by weight, less than 8.9 parts by weight, less than 8.8 parts by weight, less than 8.7 parts by weight, less than 8.6 parts by weight, less than 8.5 parts by weight, less than 8.4 parts by weight, less than 8.3 parts by weight, less than 8.2 parts by weight, 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.It may contain 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.

[0159] If the content of the second dispersant is less than 0.001 parts by weight based on 100 parts by weight of the carbon nanotube dispersion, an effective dispersing effect may not be achieved, resulting in a problem in which the viscosity of the dispersion may not be formed low and the viscosity may increase over time. If it exceeds 9 parts by weight, the content of the second dispersant is excessive, so there may be a problem in which coagulation occurs between solids in the dispersion and the viscosity of the dispersion becomes high.

[0160] In one specific example of the present invention, the first dispersant and the second dispersant of the carbon nanotube dispersion may be included in a weight ratio of 100:10 to 100:90, for example, the second dispersant may be included in a weight ratio of 100:10 or more, 100:15 or more, 100:17.65 or more, 100:20 or more, 100:25 or more, 100:30 or more, 100:33.33 or more, 100:35 or more, 100:40 or more, 100:45 or more, 100:50 or more, or 100:55 or more, relative to the first dispersant, the second dispersant may be included in a weight ratio of 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 It can be included in 100:60 or less.

[0161] When the contents of the first dispersant and the second dispersant are included in the carbon nanotube dispersion in the above weight ratio, the carbon nanotubes are uniformly dispersed in the carbon nanotube dispersion, and the viscosity can be maintained at a constant level over time with low viscosity.

[0162]

[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 supply the carbon nanotube dispersion by pre-dispersing it to prevent agglomeration when using the carbon nanotubes in a powdered state directly in the manufacture of an electrode slurry composition.

[0165] The solvent is capable of dissolving or dispersing the carbon nanotubes, the first dispersant, and the second dispersant to a certain level or higher. The aqueous solvent may be, for example, water, and the aqueous solvent may be included in an amount such that the electrode slurry composition can have an appropriate viscosity, taking into account the coating properties of the electrode slurry composition manufactured thereafter using the carbon nanotube dispersion.

[0166] A carbon nanotube dispersion according to one embodiment of the present invention can reduce the average particle size distribution of dispersed particles included in the dispersion, such as a composite of carbon nanotubes and each dispersant, by enabling the first dispersant and the second dispersant to uniformly disperse carbon nanotubes in a solvent as described above.

[0167] Average particle size distribution (D) of the dispersed particles contained in the above dispersion 50 ) may be, for example, 0.5 to 10 μm, 1 to 10 μm, 1 to 8 μm, and preferably 1 to 5 μm.

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

[0169] The above carbon nanotube dispersion may have an initial viscosity of 1 to 8 Pa·s as measured at 25°C and 1 rpm using a viscometer (TOKI SANGYO, viscometer TV-25, Rotor Code 01), 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, 2.8 Pa·s or more, 2.9 Pa·s or more. It can be 3 Pa·s or more, 3.1 Pa·s or more, 3.2 Pa·s or more, 3.3 Pa·s or more, 3.4 Pa·s or more, 3.5 Pa·s or more, 3.6 Pa·s or more, 3.7 Pa·s or more, 3.8 Pa·s or more, 3.9 Pa·s or more, 4 Pa·s or more, 4.1 Pa·s or more, 4.2 Pa·s or more, 4.3 Pa·s or more, 4.4 Pa·s or more, or 4.5 Pa·s or more, and 8 Pa·s or less, 7.9 Pa·s or less, 7.8 Pa·s or less, 7.7 Pa·s or less, 7.6 Pa·s or less, 7.5 Pa·s or less, 7.4 Pa·s or less, 7.3 Pa·s or less, 7.2 Pa·s or less, 7.1 Pa·s or less, 7 Pa·s or less, 6.9 Pa·s Below, 6.8 Pa·s or less, 6.7 Pa·s or less, 6.6 Pa·s or less, 6.5 Pa·s or less, 6.4 Pa·s 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, 5.6 Pa·s or less, 5.5 Pa·s or less, 5.4 Pa·s or less, 5.3 Pa·s or less, 5.2 Pa·s or less, 5.1 Pa·s or less, 5 Pa·s or less, 4.It may be 9 Pa·s or less, 4.8 Pa·s or less, 4.7 Pa·s or less, or 4.6 Pa·s or less. When the carbon nanotube dispersion has an initial viscosity within the above range, an electrode slurry can be manufactured more smoothly using the same, and an electrode slurry including the carbon nanotube dispersion can have an appropriate viscosity for electrode formation.

[0170] In addition, when the carbon nanotube dispersion is left at 25°C for one week, the viscosity increase rate calculated by the following equation (1) is 0.1% or more to 15% or less, specifically 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, It can be less than 2.4%, less than 2%, less than 1.5%, or less than 1%.

[0171] [Formula 1]

[0172] Viscosity increase rate (%) = {(Viscosity measured after leaving at 25℃ for 1 week - Initial viscosity) / Initial viscosity} × 100

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

[0174]

[0175] Method for producing carbon nanotube dispersion

[0176] Hereinafter, a method for producing a carbon nanotube dispersion according to one embodiment of the present invention will be described.

[0177] A method for producing a carbon nanotube dispersion according to the present invention comprises: (1) a step of mixing carbon nanotubes, a first dispersant containing nitrogen atoms, a second dispersant containing a compound represented by the following chemical formula 1, and a solvent to produce a carbon nanotube primary dispersion; and (2) a step of dispersing the carbon nanotube primary dispersion to produce a carbon nanotube secondary dispersion.

[0178] [Chemical Formula 1]

[0179]

[0180] In the above chemical formula 1,

[0181] Ar1 and Ar2 are each independently a substituted or unsubstituted C6 to C30 aryl group.

[0182] In step (1), a carbon nanotube primary dispersion is prepared by mixing carbon nanotubes, a first dispersant containing nitrogen atoms, a second dispersant containing a compound represented by the following chemical formula 1, and a solvent. The step of preparing the carbon nanotube primary dispersion is performed through a wetting process in which each component is evenly mixed.

[0183] The specific description of the carbon nanotubes, the first dispersant containing nitrogen atoms, the second dispersant containing a compound represented by the following chemical formula 1, and the solvent according to the method for producing the above carbon nanotube dispersion is as described above, and therefore, a specific description will be omitted below.

[0184] The mixing for preparing the above carbon nanotube primary dispersion may be performed using a conventional mixing method, specifically, a mixing device such as a pony mixer, a change-can 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 attrition mill, a universal stirrer, a clear mixer, or a TK mixer, and may include a step of mixing at a rotation speed of 300 to 5,000 rpm for 30 minutes to 7 hours.

[0185] In addition, when mixing to prepare the primary carbon nanotube dispersion, cavitation dispersion treatment may be performed to increase the miscibility of the carbon nanotubes and the solvent, or the dispersibility of the carbon nanotubes in the solvent. The cavitation dispersion treatment is a dispersion treatment method that utilizes shock waves generated by the bursting of vacuum bubbles formed in water when high energy is applied to the liquid, and the method can disperse the carbon nanotubes without damaging the properties of the carbon nanotubes. Specifically, the cavitation dispersion treatment can be performed by ultrasonic, jet mill, or shear dispersion treatment.

[0186] The step of preparing the above carbon nanotube primary dispersion may be performed under temperature conditions in which the viscosity of the mixture and other physical properties do not change due to evaporation of the solvent. For example, it may be performed at a temperature of 50°C or lower, more specifically, from 5°C to 50°C.

[0187] In step (2), the above carbon nanotube primary dispersion is dispersed to prepare a carbon nanotube secondary dispersion.

[0188] The process for producing the above carbon nanotube secondary dispersion can be performed by a method such as a ball mill, a bead mill, a disc mill, a basket mill, a high pressure homogenizer, etc., and more specifically, it can be performed by a dispersion method using a high pressure homogenizer.

[0189] Dispersion by the high-pressure disperser is achieved by pressurizing the mixture with a plunger pump of the high-pressure disperser, for example, and pushing it through the gap of the dispersion valve, thereby generating forces such as cavitation, shear, impact, and explosion when passing through the gap.

[0190] The above dispersion process can be performed depending on the degree of dispersion of the carbon nanotube dispersion, and specifically, can be performed under a pressure of 5,000 to 30,000 psi for 30 to 120 minutes, more specifically, 60 to 90 minutes, and the above process can be repeated 1 to 10 times.

[0191] The carbon nanotube dispersion according to the present invention may refer to the carbon nanotube secondary dispersion.

[0192]

[0193] Electrode slurry composition for lithium secondary batteries

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

[0195] The above-mentioned electrode slurry composition for a lithium secondary battery may be a positive electrode slurry composition or a negative electrode slurry composition, and specifically, may be a negative electrode slurry composition.

[0196] The above-described electrode slurry composition for a lithium secondary battery may 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, and for example, lithium cobalt-based oxide, lithium nickel-based oxide, lithium manganese-based oxide, lithium iron phosphate, lithium nickel manganese cobalt-based oxide, or a combination thereof can be used. Specifically, the positive electrode active material includes LiCoO2, LiNiO2, LiMn2O4, LiCoPO4, LiFePO4, and LiNiaMnbCocO. 2　 (Here, 0 < a, b, c < 1) can be used, but is not limited to this.

[0198] The above negative active materials include natural graphite, artificial graphite, carbonaceous materials; lithium-containing titanium composite oxide (LTO); metals (Me) such as Si, Sn, Li, Zn, Mg, Cd, Ce, Ni or Fe; alloys composed of the above metals (Me); oxides (MeO) of the above metals (Me). x ); and one or more types of negative electrode active materials selected from the group consisting of a complex of the above metal (Me) and carbon. The negative electrode active material may be included in an amount of 60 to 98 wt%, more preferably 70 to 98 wt%, based on the total weight of solids excluding the solvent in the negative electrode slurry.

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

[0200] The solvents mentioned above include organic solvents such as N-methyl pyrrolidone (NMP), dimethyl formamide (DMF), acetone, dimethyl acetamide, etc., or water, and these solvents may be used alone or in combination of two or more. The amount of solvent used is sufficient to dissolve and disperse the electrode active material, binder, and conductive agent, taking into account the coating thickness of the slurry and the manufacturing yield.

[0201] The above viscosity modifier may be carboxymethylcellulose, polyacrylic acid, or the like, and by adding it, the viscosity of the electrode slurry can be adjusted to facilitate the manufacturing of the electrode slurry and the application process on the electrode current collector.

[0202] The above filler is optionally used as a component that suppresses expansion of the electrode, and is not particularly limited as long as it is a fibrous material that does not cause chemical changes in the battery. For example, olefin-based polymers such as polyethylene and polypropylene; fibrous materials such as glass fiber and carbon fiber are used.

[0203] When the above electrode slurry composition is a composition of a positive electrode slurry for forming a positive electrode, the positive electrode can be manufactured by applying the composition of the positive electrode slurry onto a positive electrode current collector, followed by drying and rolling. Alternatively, the positive electrode slurry can be manufactured by casting the positive electrode slurry onto a separate support, and then laminating the film obtained by peeling it off from the support onto the positive electrode current collector.

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

[0205] The above-described positive electrode current collector generally has a thickness of 3 μm to 500 μm. The positive electrode current collector is not particularly limited as long as it has high conductivity and does not cause chemical changes in the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used. In addition, the surface of the positive electrode current collector may be formed with fine irregularities to strengthen the bonding strength of the positive electrode active material, and the positive electrode current collector can be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0206] When the above electrode slurry composition is a composition of a negative electrode slurry for forming a negative electrode, the negative electrode can be manufactured by applying the composition of the negative electrode slurry onto a negative electrode current collector, followed by drying and rolling. Alternatively, the negative electrode slurry can be manufactured by casting the negative electrode slurry onto a separate support, and then laminating the resulting film onto the negative electrode current collector by peeling it off from the support.

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

[0208] The above negative electrode current collector generally has a thickness of 3 ㎛ to 500 ㎛. The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, like the negative electrode current collector, the bonding strength of the negative electrode active material can be strengthened by forming fine unevenness on the surface, and can be used in various forms such as a film, sheet, foil, net, porous body, foam, non-woven fabric, etc.

[0209]

[0210] lithium secondary battery

[0211] A lithium secondary battery includes a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte. The positive electrode and the negative electrode are the same as those described above, so a detailed description thereof will be omitted.

[0212] The above separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries can be used without any particular restrictions, and in particular, one having low resistance to ion movement of the electrolyte and excellent electrolyte moisture absorption capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, may be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength may be used, and may optionally be used in a single-layer or multi-layer structure.

[0213] The electrolyte may be, but is not limited to, an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc. that can be used in the manufacture of a lithium secondary battery. Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0214] 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 include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; Carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (wherein R is a C2 to C20 linear, branched, or cyclic hydrocarbon group, and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used. Among these, a carbonate solvent is preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery and a linear carbonate compound having low viscosity (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) is more preferable.In this case, the performance of the electrolyte may be excellent when the cyclic carbonate and the chain carbonate are mixed and used in a volume ratio of about 1:1 to about 1:9.

[0215] The lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt may include LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2. LiCl, LiI, or LiB(C2O4)2. It is preferable that the concentration of the lithium salt be used within the range of 0.1M to 2.0M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0216] In addition to the electrolyte components, the electrolyte may further include one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additives may be included in an amount of 0.1 wt% to 5 wt% based on the total weight of the electrolyte.

[0217] A lithium secondary battery comprising an electrode manufactured using a carbon nanotube dispersion according to the present invention, specifically a lithium secondary battery comprising an anode manufactured using a carbon nanotube dispersion, has carbon nanotubes uniformly dispersed within the anode, and can reduce the content thereof compared to a case where a conductive material such as conventional carbon black is included, thereby stably exhibiting excellent discharge capacity and output characteristics. As a result, the lithium secondary battery can be usefully used in portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).

[0218] Accordingly, according to another embodiment of the present invention, the lithium secondary battery, a battery module including the lithium secondary battery as a unit cell, and a battery pack including the same can be provided.

[0219] The above battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, such as a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0220] Below, specific embodiments of the present invention are presented. However, the embodiments described below are intended solely to specifically illustrate or explain the present invention and are not intended to limit the scope of the invention. Furthermore, any details not described herein are technically feasible to those skilled in the art and thus are omitted.

[0221]

[0222] Example

[0223]

[0224] Example 1a

[0225] (1) 5.625 g of polyvinylpyrrolidone (PVP) (PVP K15, manufactured by Zhangzhou Huafu Chemical) as a first dispersant containing nitrogen atoms (1.125 parts by weight relative to 100 parts by weight of the entire carbon nanotube dispersion), 1.875 g of Nitrazine Yellow (manufactured by Sigma Aldrich) as a second dispersant containing a compound represented by the chemical formula 1 (0.375 parts by weight relative to 100 parts by weight of the entire carbon nanotube dispersion), and 487.5 g of water as a solvent are mixed to prepare a 495 g mixed solution, which is then placed in a dissolution tank equipped with an impeller and a container (dissolver, Dispermat-CA, manufactured by VMA-GETZMANN) and stirred at 400 rpm for 10 minutes to mix.

[0226] The above mixture has a specific surface area of ​​1,160 m 2 / g, average particle size (D 50 ) 5.0 g (1.0 part by weight based on 100 parts by weight of the total carbon nanotube dispersion) of 5 ㎛ single-walled carbon nanotubes (SWCNT, TUBALL, manufactured by OCSiAl) is additionally added and stirred at 8,000 rpm for 60 minutes to prepare a total of 500 g of a primary carbon nanotube dispersion.

[0227] (3) The carbon nanotube primary dispersion was homogeneously dispersed 7 times at a pressure of 20,000 psi using a high-pressure disperser (PICOMAX, manufactured by Micronox) to prepare a carbon nanotube secondary dispersion.

[0228]

[0229] Example 2a

[0230] In the above Example 1a, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1a, except that the content of the first dispersant was 5.0 g (1.0 part by weight relative to 100 parts by weight of the total carbon nanotube dispersion) and the content of the second dispersant was 2.5 g (0.5 part by weight relative to 100 parts by weight of the total carbon nanotube dispersion).

[0231]

[0232] Example 3a

[0233] In the above Example 1a, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1a, except that the content of the first dispersant was 3.375 g (0.675 parts by weight relative to 100 parts by weight of the entire carbon nanotube dispersion), the content of the second dispersant was 1.125 g (0.225 parts by weight relative to 100 parts by weight of the entire carbon nanotube dispersion), and the content of the carbon nanotubes was 3.0 g (0.6 parts by weight relative to 100 parts by weight of the entire carbon nanotube dispersion).

[0234]

[0235] Example 1b

[0236] (1) 4.5 g of polyvinylpyrrolidone (PVP) (PVP K15, manufactured by Zhangzhou Huafu Chemical) as a first dispersant containing nitrogen atoms (0.9 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion), 1.5 g of Hydroxynaphthol Blue (manufactured by Sigma Aldrich) as a second dispersant containing a compound represented by the chemical formula 1 (0.3 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion), and 490 g of water as a solvent are mixed to prepare a 496 g mixed solution, which is then placed in a dissolution tank equipped with an impeller and a container (dissolver, Dispermat-CA, manufactured by VMA-GETZMANN) and stirred at 400 rpm for 10 minutes to mix.

[0237] The above mixture has a specific surface area of ​​1,160 m 2 / g, average particle size (D 50 ) 4.0 g (0.8 parts by weight based on 100 parts by weight of the total carbon nanotube dispersion) of 5 ㎛ single-walled carbon nanotubes (SWCNT, TUBALL, manufactured by OCSiAl) is additionally added and stirred at 8,000 rpm for 60 minutes to prepare a total of 500 g of a primary carbon nanotube dispersion.

[0238] (3) The carbon nanotube primary dispersion was homogeneously dispersed 7 times at a pressure of 14,000 psi using a high-pressure disperser (PICOMAX, manufactured by Micronox) to prepare a carbon nanotube secondary dispersion.

[0239]

[0240] Example 2b

[0241] In the above Example 1b, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1b, except that the content of the first dispersant was 4.8 g (0.96 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion) and the content of the second dispersant was 1.2 g (0.24 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion).

[0242]

[0243] Example 3b

[0244] In the above Example 1b, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1b, except that the content of the first dispersant was 4.0 g (0.8 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion) and the content of the second dispersant was 2.0 g (0.4 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion).

[0245]

[0246] Example 1c

[0247] (1) 4.5 g of polyvinylpyrrolidone (PVP) (PVP K15, Zhangzhou Huafu Chemical) as a first dispersant containing nitrogen atoms (0.9 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion), 1.5 g of Methyl Orange (Sigma Aldrich) as a second dispersant of aniline compounds (0.3 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion), and 490 g of water as a solvent are mixed to prepare a 496 g mixed solution, which is then placed in a dissolution tank equipped with an impeller and a container (dissolver, Dispermat-CA, VMA-GETZMANN) and stirred at 400 rpm for 10 minutes to mix.

[0248] The above mixture has a specific surface area of ​​1,160 m 2 / g, average particle size (D 50 ) 4.0 g (0.8 parts by weight based on 100 parts by weight of the total carbon nanotube dispersion) of 5 ㎛ single-walled carbon nanotubes (SWCNT, TUBALL, manufactured by OCSiAl) is additionally added and stirred at 8,000 rpm for 60 minutes to prepare a total of 500 g of a primary carbon nanotube dispersion.

[0249] (3) The carbon nanotube primary dispersion was homogeneously dispersed 7 times at a pressure of 14,000 psi using a high-pressure disperser (PICOMAX, manufactured by Micronox) to prepare a carbon nanotube secondary dispersion.

[0250]

[0251] Example 2c

[0252] In the above Example 1c, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1c, except that the content of the first dispersant was 4.8 g (0.96 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion) and the content of the second dispersant was 1.2 g (0.24 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion).

[0253]

[0254] Example 3c

[0255] In the above Example 1c, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1c, except that the content of the first dispersant was 4.0 g (0.8 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion) and the content of the second dispersant was 2.0 g (0.4 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion).

[0256]

[0257] Comparative Example 1a

[0258] In the above Example 1a, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1a, except that the second dispersant was not added.

[0259]

[0260] Comparative Example 2a

[0261] In the above Example 1a, 3.0 g (0.6 parts by weight relative to 100 parts by weight of the entire carbon nanotube dispersion) and 4.5 g (0.9 parts by weight relative to 100 parts by weight of the entire carbon nanotube dispersion) of the first dispersant were added, but the second dispersant was not added, and a carbon nanotube dispersion was prepared in the same manner as in the above Example 1a.

[0262]

[0263] Comparative Example 3a

[0264] In the above Example 1a, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1a, except that the content of the first dispersant was 7.275 g (1.455 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion) and the content of the second dispersant was 0.225 g (0.045 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion).

[0265]

[0266] Comparative Example 4a

[0267] In the above Example 1a, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1a, except that the first dispersant was not added and the content of the second dispersant was set to 7.5 g (1.5 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion).

[0268]

[0269] Comparative Example 5a

[0270] In the above Example 1a, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1a, except that the content of the first dispersant was set to 0.225 g (0.045 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion) and the content of the second dispersant was set to 7.275 g (1.455 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion).

[0271]

[0272] Comparative Example 6a

[0273] In the above Example 3a, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1a, except that 1.125 g of tristyrylphenol ethoxylate (0.225 parts by weight based on 100 parts by weight of the total carbon nanotube dispersion) was used as the second dispersant instead of Nitrazine Yellow.

[0274]

[0275] Comparative Example 7a

[0276] In the above Example 3a, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1a, except that 1.125 g of styrene maleic acid copolymer (0.225 parts by weight based on 100 parts by weight of the total carbon nanotube dispersion) was used instead of Nitrazine Yellow as the second dispersant.

[0277]

[0278] Comparative Example 8a

[0279] In the above Example 3a, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1a, except that 1.125 g (0.225 parts by weight based on 100 parts by weight of the total carbon nanotube dispersion) of Yellow No. 3 (Sigma-Aldrich) was used instead of Nitrazine Yellow as the second dispersant.

[0280]

[0281] Comparative Example 1b

[0282] In the above Example 1b, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1b, except that the content of the first dispersant was 6.0 g (1.2 parts by weight based on 100 parts by weight of the total carbon nanotube dispersion) and the second dispersant was not added.

[0283]

[0284] Comparative Example 2b

[0285] In the above Example 1b, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1b, except that the content of the first dispersant was 3.0 g (0.6 part by weight relative to 100 parts by weight of the total carbon nanotube dispersion) and the content of the second dispersant was 3.0 g (0.6 part by weight relative to 100 parts by weight of the total carbon nanotube dispersion).

[0286]

[0287] Comparative Example 3b

[0288] In the above Example 1b, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1b, except that the content of the first dispersant was 5.6 g (1.12 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion) and the content of the second dispersant was 0.4 g (0.08 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion).

[0289]

[0290] Comparative Example 4b

[0291] In the above Example 1b, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1b, except that the content of the second dispersant was added in an amount of 6.0 g (1.2 parts by weight based on 100 parts by weight of the total carbon nanotube dispersion), but the first dispersant was not added.

[0292]

[0293] Comparative Example 5b

[0294] In the above Example 3b, a carbon nanotube dispersion was prepared in the same manner as in the above Example 3b, except that the content of the first dispersant was changed to 3.375 g (0.6 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion), and that the content of the second dispersant was changed to 1.125 g of tristyrylphenol ethoxylate (0.225 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion) instead of Hydroxynaphthol Blue (manufactured by Sigma Aldrich).

[0295]

[0296] Comparative Example 6b

[0297] In the above Example 3b, a carbon nanotube dispersion was prepared in the same manner as in the above Example 3b, except that the content of the first dispersant was 3.375 g (0.6 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion), and the content of the second dispersant was 1.125 g (0.225 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion) of a styrene maleic acid copolymer instead of Hydroxynaphthol Blue (manufactured by Sigma Aldrich).

[0298]

[0299] Comparative Example 1c

[0300] In the above Example 1c, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1c, except that the content of the first dispersant was 6.0 g (1.2 parts by weight based on 100 parts by weight of the total carbon nanotube dispersion) and the second dispersant was not added.

[0301]

[0302] Comparative Example 2c

[0303] In the above Example 1c, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1c, except that the content of the first dispersant was 3.0 g (0.6 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion) and the content of the second dispersant was 3.0 g (0.6 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion).

[0304]

[0305] Comparative Example 3c

[0306] In the above Example 1c, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1c, except that the content of the first dispersant was 5.6 g (1.12 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion) and the content of the second dispersant was 0.4 g (0.08 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion).

[0307]

[0308] Comparative Example 4c

[0309] In the above Example 1c, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1c, except that the content of the second dispersant was added in an amount of 6.0 g (1.2 parts by weight based on 100 parts by weight of the total carbon nanotube dispersion), but the first dispersant was not added.

[0310]

[0311] Comparative Example 5c

[0312] In the above Example 3c, a carbon nanotube dispersion was prepared in the same manner as in the above Example 3c, except that the content of the first dispersant was 3.375 g (0.6 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion), and the content of the second dispersant was 1.125 g of tristyrylphenol ethoxylate (0.225 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion) instead of Methyl Orange (manufactured by Sigma Aldrich).

[0313]

[0314] Comparative Example 6c

[0315] In the above Example 3c, a carbon nanotube dispersion was prepared in the same manner as in the above Example 3c, except that the content of the first dispersant was 3.375 g (0.6 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion), and the content of the second dispersant was 1.125 g (0.225 parts by weight relative to 100 parts by weight of the total carbon nanotube dispersion) of a styrene maleic acid copolymer instead of Methyl Orange (manufactured by Sigma Aldrich).

[0316]

[0317] Comparative Example 7c

[0318] In the above Example 1c, a carbon nanotube dispersion was prepared in the same manner as in the above Example 1c, except that 4.5 g of polyvinyl alcohol (PVA) (0.9 parts by weight based on 100 parts by weight of the total carbon nanotube dispersion) was used instead of polyvinylpyrrolidone (PVP) as the first dispersant.

[0319]

[0320] Experimental example

[0321] The viscosity of the carbon nanotube dispersions of Examples 1a to 3a and Comparative Examples 1a to 8a was measured, and the viscosity was measured again after leaving them at 25°C for one week, and the results are shown in Table 1 below.

[0322] The viscosity of the carbon nanotube dispersions of Examples 1b to 3b and Comparative Examples 1b to 6b was measured, and the viscosity was measured again after leaving them at 25°C for one week, and the results are shown in Table 2 below.

[0323] The viscosity of the carbon nanotube dispersions of Examples 1c to 3c and Comparative Examples 1c to 6c was measured, and the viscosity was measured again after leaving them at 25°C for one week, and the results are shown in Table 3 below.

[0324] Viscosity was measured at 25°C and 1 rpm using a viscometer (TOKI SANGYO, viscometer TV-25, Rotor Code 01).

[0325] CNT content (parts by weight) 1st dispersant 2nd dispersant Viscosity Type Content (parts by weight) Type Content (parts by weight) After dispersion (Pa·s) After 1 week (Pa·s) Increase rate (%) Example 1a1 PVP 1.125 Nitrazine Yellow 0.37 5 6.36 9 9.5 Example 2a1 PVP 1.000 Nitrazine Yellow 0.50 0 7.38 2 1 2.3 Example 3a0.6 PVP 0.675 Nitrazine Yellow 0.22 5 2.5 2.67 6.8 Comparative Example 1a1 PVP 1.125--24.0 3 0.0 2 5.0 Comparative Example 2a0.6 PVP 0.900--12.0 1 4.6 2 1.7 Comparative Example 3a1PVP1.455NitrazineYellow0.04519.521.28.7Comparative Example 4a1--NitrazineYellow1.500Viscosity not measurableViscosity not measurableViscosity not measurableComparative Example 5a1PVP0.045NitrazineYellow1.455Viscosity not measurableViscosity not measurableComparative Example 6a0.6PVP0.675Tristyrylphenol ethoxylate0.22518.424.533.2Comparative Example 7a0.6PVP0.675Styrene maleic acid copolymer0.2259.717.075.3Comparative Example 8a0.6PVP0.675Yellow No. 30.2258.714.364.0

[0326] (* The contents of CNT, first dispersant, and second dispersant are based on 100 parts by weight of the entire carbon nanotube dispersion)

[0327]

[0328] Referring to Table 1 above, it can be confirmed that the carbon nanotube dispersions of Examples 1a to 3a, which include Nitrazine Yellow, a compound represented by Chemical Formula 1 of the present invention, as a second dispersant and a first dispersant, have a lower initial viscosity immediately after dispersing carbon nanotubes in an aqueous solvent, and in particular, the increase in viscosity of the carbon nanotube dispersion over time is very effectively suppressed.

[0329] In the case of the carbon nanotube dispersion of Comparative Example 2a, the carbon nanotube content was reduced compared to the carbon nanotube dispersion of Comparative Example 1a, so that the initial viscosity immediately after dispersing the carbon nanotubes in the aqueous solvent and the viscosity of the dispersion after 1 week were reduced compared to the carbon nanotube dispersion of Comparative Example 1a. However, as with the carbon nanotube dispersion of Comparative Example 1a, it was found that the effect of suppressing the viscosity increase of the dispersion according to the change over time was not exhibited because the second dispersing agent including the compound represented by the chemical formula 1 of the present invention was not included compared to Examples 1a to 3a.

[0330] In the case of the carbon nanotube dispersion of Comparative Example 3a, it can be seen that the initial viscosity immediately after dispersing the carbon nanotubes in the aqueous solvent is high because the second dispersant, which is a compound represented by the chemical formula 1 according to the present invention, is included in a content less than a certain level.

[0331] In the case of the carbon nanotube dispersions of Comparative Examples 4a and 5a, compared to the carbon nanotube dispersions of Examples 1a to 3a, the first dispersant was not included (Comparative Example 4a) or the first dispersant was included in an amount less than a certain amount (Comparative Example 5a), so the carbon nanotubes could not be completely dispersed in the aqueous solvent, and coagulation of the dispersion occurred, making it impossible to measure the viscosity.

[0332] In the case of the carbon nanotube dispersions of Comparative Examples 6a and 7a, compared to the carbon nanotube dispersions of Examples 1a to 3a, since the compound represented by Chemical Formula 1 according to the present invention was not used as a second dispersant, it can be seen that the initial viscosity immediately after dispersing the carbon nanotubes in the aqueous solvent was high, and the effect of suppressing the increase in viscosity of the carbon nanotube dispersion over time was not exhibited.

[0333] In the case of the carbon nanotube dispersion of Comparative Example 8a, unlike the carbon nanotube dispersions of Examples 1a to 3a which include the compound represented by Chemical Formula 1 according to the present invention as a second dispersant, the compound included as the dispersant does not include different aryl groups, and thus the pi-pi (π-π) interaction with the carbon nanotubes cannot be stably generated in a local region, and thus the bonding force between the dispersant and the carbon nanotubes is reduced, and the content of the remaining dispersant that is not effectively adsorbed to the surface of the carbon nanotubes increases, and as a result of the agglomeration of the remaining dispersants, it can be seen that the effect of suppressing the increase in viscosity of the dispersion due to changes over time is not expressed.

[0334]

[0335] CNT content (parts by weight) 1st dispersant 2nd dispersant ratioViscosity type content (parts by weight) Type content (parts by weight) After dispersion (Pa·s) After 1 week (Pa·s) Increase rate (%) Example 1b 0.8 PVP 0.9 Hydroxynaphthol Blue 0.3 100:33 3.8 3.93 Example 2b 0.8 PVP 0.96 Hydroxynaphthol Blue 0.24 100:25 3.3 3.43 Example 3b 0.8 PVP 0.8 Hydroxynaphthol Blue 0.4 100:50 3.5 3.89 Comparative example 1b 0.8 PVP 1.2--- 18.5 26.8 45 Comparative example 2b 0.8 PVP 0.6 Hydroxynaphthol Blue0.6100:10013.416.725Comparative Example 3b0.8PVP1.12Hydroxynaphthol Blue0.08100:7.116.924.042Comparative Example 4b0.8--Hydroxynaphthol Blue1.2-7.011.260Comparative Example 5b0.6PVP0.675Tristyrylphenol ethoxylate0.225100:3318.424.533Comparative Example 6b0.6PVP0.675Styrene maleic acid copolymer0.225100:339.717.075

[0336] (* The contents of CNT, first dispersant, and second dispersant are based on 100 parts by weight of the entire carbon nanotube dispersion)

[0337] (* 'Ratio' is the weight ratio of the second dispersant to the first dispersant)

[0338]

[0339] Referring to Table 2 above, it can be confirmed that the carbon nanotube dispersions of Examples 1b to 3b, which include the first dispersant and Hydroxynaphthol Blue, a compound represented by Chemical Formula 1 of the present invention, as a second dispersant, have a lower initial viscosity immediately after dispersing carbon nanotubes in an aqueous solvent, and in particular, the viscosity increase of the carbon nanotube dispersion over time is very effectively suppressed.

[0340] In the case of the carbon nanotube dispersions of Comparative Examples 2b and 3b, compared to the carbon nanotube dispersions of Examples 1b to 3b, the second dispersant was included in excess (Comparative Example 2b) or included in less than a certain amount (Comparative Example 3b), so that the initial viscosity immediately after dispersing the carbon nanotubes in the aqueous solvent was high, and the effect of suppressing the viscosity increase of the dispersion over time was not observed.

[0341] In the case of the carbon nanotube dispersion of Comparative Example 4b, it can be confirmed that there is a problem in which the viscosity of the carbon nanotube dispersion rapidly increases over time as compared to the carbon nanotube dispersions of Examples 1b to 3b, as the first dispersant is not included.

[0342] In the case of the carbon nanotube dispersions of Comparative Examples 5b and 6b, compared to the carbon nanotube dispersions of Examples 1b to 3b, since the compound represented by Chemical Formula 1 according to the present invention was not used as a second dispersant, it can be seen that the initial viscosity immediately after dispersing the carbon nanotubes in the aqueous solvent was high, and the effect of suppressing the increase in viscosity of the carbon nanotube dispersion over time was not exhibited.

[0343]

[0344] CNT content (parts by weight) 1st dispersant 2nd dispersant ratioViscosity type content (parts by weight) Type content (parts by weight) After dispersion (Pa·s) After 1 week (Pa·s) Increase rate (%) Example 1c0.8PVP0.9Methyl Orange0.3100:333.73.95 Example 2c0.8PVP0.96Methyl Orange0.24100:254.14.35 Example 3c0.8PVP0.8Methyl Orange0.4100:504.24.32 Comparative example 1c0.8PVP1.2---18.526.845 Comparative example 2c0.8PVP0.6Methyl Orange0.6100:10011.216.648 Comparative example 3c0.8PVP1.12Methyl Orange 0.08 100:7.1 14.32 0.342 Comparative Example 4c 0.8--Methyl Orange 1.2-8.2 14.172 Comparative Example 5c 0.6 PVP 0.675 Tristyrylphenol ethoxylate 0.225 100:33 18.4 2 4.533 Comparative Example 6c 0.6 PVP 0.675 Styrene maleic acid copolymer 0.225 100:339.7 17.075 Comparative Example 7c 0.8 PVA 0.9 Methyl Orange 0.31 00:33 17.32 3.838

[0345] (* The contents of CNT, first dispersant, and second dispersant are based on 100 parts by weight of the entire carbon nanotube dispersion)

[0346] (* 'Ratio' is the weight ratio of the second dispersant to the first dispersant)

[0347]

[0348] Referring to Table 3 above, it can be confirmed that the carbon nanotube dispersions of Examples 1c to 3c, which include Methyl Orange, an aniline-based compound of the present invention, as a second dispersant and a first dispersant, have a lower initial viscosity immediately after dispersing carbon nanotubes in an aqueous solvent, and in particular, the increase in viscosity of the carbon nanotube dispersion over time is very effectively suppressed.

[0349] In the case of the carbon nanotube dispersions of Comparative Examples 2c and 3c, compared to the carbon nanotube dispersions of Examples 1c to 3c, the second dispersant was included in an excessive amount (Comparative Example 2c) or was included in an amount less than a certain amount (Comparative Example 3c), so that the initial viscosity immediately after dispersing the carbon nanotubes in the aqueous solvent was high, and the effect of suppressing the viscosity increase of the dispersion over time was not observed.

[0350] In the case of the carbon nanotube dispersion of Comparative Example 4c, it can be confirmed that there is a problem in which the viscosity of the carbon nanotube dispersion rapidly increases over time as compared to the carbon nanotube dispersions of Examples 1c to 3c, as the first dispersant is not included.

[0351] In the case of the carbon nanotube dispersions of Comparative Examples 5c and 6c, compared to the carbon nanotube dispersions of Examples 1c to 3c, since the aniline-based compound according to the present invention was not used as a second dispersant, it can be seen that the initial viscosity immediately after dispersing the carbon nanotubes in the aqueous solvent was high, and the effect of suppressing the increase in viscosity of the carbon nanotube dispersion over time was not exhibited.

[0352] In the case of the carbon nanotube dispersion of Comparative Example 7c, since the first dispersant containing nitrogen atoms was not used as the first dispersant compared to the carbon nanotube dispersion of Example 1c, it can be seen that the initial viscosity immediately after dispersing the carbon nanotubes in the aqueous solvent was high, and the effect of suppressing the increase in viscosity of the carbon nanotube dispersion over time was not exhibited.

[0353]

[0354] Accordingly, it was confirmed that the carbon nanotube dispersion, in which carbon nanotubes are dispersed in an aqueous solvent, includes a first dispersant containing nitrogen atoms and a second dispersant containing a compound represented by the chemical formula 1 according to the present invention, and that the carbon nanotube dispersion exhibits low viscosity and that the increase in viscosity due to changes over time can be suppressed only when the first dispersant and the second dispersant are included in a certain weight ratio.

[0355]

[0356] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

Claims

1. Carbon nanotubes; A first dispersant comprising a nitrogen atom; A second dispersant comprising a compound represented by the following chemical formula 1; and Containing a solvent, Carbon nanotube dispersions: [Chemical Formula 1] In the above chemical formula 1, Ar1 and Ar2 are each independently a substituted or unsubstituted C6 to C30 aryl group.

2. In paragraph 1, Ar1 and Ar2 of the above chemical formula 1 are each represented by the following chemical formula 2 or chemical formula 3, Carbon nanotube dispersions: [Chemical Formula 2] [Chemical Formula 3] In the above chemical formula 2, R1 to R8 are the same or different, and each independently represent hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; nitro group; substituted or unsubstituted C1 to C10 alkyl group; substituted or unsubstituted C1 to C10 alkoxy group; or a moiety connected to chemical formula 2, wherein any one of R1 to R8 is a moiety connected to an azo group of chemical formula 1, In the above chemical formula 3, R9 to R14 are the same or different, and each independently represent hydrogen; deuterium; halogen; cyano group; sulfonate group; amine group; nitro group; substituted or unsubstituted C1 to C10 alkoxy group; or a moiety connected to chemical formula 3, wherein any one of R9 to R14 is a moiety connected to an azo group of chemical formula 1.

3. In paragraph 1, The second dispersant comprises a compound represented by any one of the following chemical formulae 1-1a to 1-1c: Carbon nanotube dispersions: [Chemical Formula 1-1a] In the above chemical formula 1-1a, R1 to R7 are the same or different and are each independently hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; nitro group; substituted or unsubstituted C1 to C10 alkyl group; or substituted or unsubstituted C1 to C10 alkoxy group, R9 to R13 are the same or different and are each independently hydrogen; deuterium; halogen; cyano group; sulfonate group; amine group; nitro group; or a substituted or unsubstituted C1 to C10 alkoxy group; [Chemical Formula 1-1b] In the above chemical formula 1-1b, R1 to R7, R9 to R15 are the same or different, and each independently represent hydrogen; deuterium; halogen; cyano group; sulfonate group; or hydroxyl group; [Chemical Formula 1-1c] In the above chemical formula 1-1c, R1 to R5 are the same or different and are each independently hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; nitro group; or NRaRb, wherein at least one of R1 to R5 is represented by NRaRb, Ra and Rb are the same or different and are each independently hydrogen; deuterium; or a substituted or unsubstituted C1 to C10 alkyl group, R6 to R10 are the same or different, and each independently represent hydrogen; deuterium; halogen; cyano group; sulfonate group; hydroxyl group; amine group; or nitro group, provided that at least one of R6 to R10 is a sulfonate group.

4. In paragraph 1, Contains 0.05 to 5 parts by weight of carbon nanotubes based on 100 parts by weight of the above carbon nanotube dispersion. Carbon nanotube dispersion.

5. In paragraph 1, The BET surface area of ​​the above carbon nanotubes is 800 to 2,000 m 2 / g is, Carbon nanotube dispersion.

6. In paragraph 1, The first dispersant is at least one selected from the group consisting of polyvinylpyrrolidone, polyacrylic acid hydrazide, poly-N-vinyl-5-methoxazolidon, N-alkyl polyimine, N-acetyl polyimine, polyacrylamide, poly-L-lysine hydrobromide, benzyl-dodecyl-dimethylammonium chloride, and polyethylenimine. Carbon nanotube dispersion.

7. In paragraph 1, The first dispersant is included in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the carbon nanotube dispersion. Carbon nanotube dispersion.

8. In paragraph 1, The second dispersant is included in an amount of 0.001 to 9 parts by weight based on 100 parts by weight of the carbon nanotube dispersion. Carbon nanotube dispersion.

9. In paragraph 1, The first dispersant and the second dispersant are included in a weight ratio of 100:10 to 100:

90. Carbon nanotube dispersion.

10. In paragraph 1, The above carbon nanotube dispersion has an initial viscosity of 1 to 8 Pa·s measured at 25°C and 1 rpm. Carbon nanotube dispersion.

11. In paragraph 1, The above carbon nanotube dispersion has a viscosity increase rate of 15% or less, as expressed by the following formula (1). Carbon nanotube dispersions: [Formula 1] Viscosity increase rate (%) = {(Viscosity measured after leaving at 25 ℃ for 1 week - Initial viscosity) / Initial viscosity} × 100. 12.(1) A step of preparing a carbon nanotube primary dispersion by mixing carbon nanotubes, a first dispersant containing nitrogen atoms, a second dispersant containing a compound represented by the following chemical formula 1, and a solvent; and (2) A step of preparing a carbon nanotube secondary dispersion by dispersing the carbon nanotube primary dispersion; A method for producing a carbon nanotube dispersion according to claim 1, comprising: [Chemical Formula 1] In the above chemical formula 1, Ar1 and Ar2 are each independently a substituted or unsubstituted C6 to C30 aryl group.

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