Carbon nanoparticle coating method

Abstract

To provide a carbon nanoparticle coating method.SOLUTION: The present invention relates to a method by which carbon nanoparticles can be uniformly coated on the material to be coated.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for coating carbon nanoparticles. Specifically, it is an invention for providing a method by which carbon nanoparticles can be uniformly coated on a coating target substance.

Background Art

[0002] Recently, interest in energy storage technology has been increasing, and carbon materials, which were initially commercialized in leisure products, are now gradually expanding their scope of application in areas such as automobiles, aviation, IT, new materials, and renewable energy.

[0003] Nanocarbon materials refer to carbon-based nanomaterials, such as carbon quantum dots, which are zero-dimensional structures of carbon, fullerenes, carbon nanoribbons and carbon nanotubes, which are one-dimensional structures, and graphene, which is a two-dimensional structure. When classifying nanocarbon materials according to their state of matter, they can be broadly divided into carbon quantum dots, fullerenes, carbon nanoribbons, carbon nanotubes, graphene, etc., and these can be further classified into top-down and bottom-up methods according to their respective manufacturing methods.

[0004] They have the characteristics of carbon materials with high strength, high thermal conductivity, and conductivity. In particular, when the size of the material is very small, such as in the case of carbon quantum dots, various quantum physical phenomena (such as luminescence phenomena, changes in band gaps, and down-conversion due to energy transitions) can be observed. Such nanocarbon materials have excellent electrical, physical, chemical, and mechanical properties and are prominent as new materials that overcome the technical limitations of existing industrial fields.

[0005] With the trend of gradually replacing existing component materials with carbon materials, private companies are also actively researching ways to increase their interest in carbon materials and commercialize them in order to enhance their competitiveness. Among these, nanocarbon materials, as conductive materials, are prominent in applications such as electromagnetic wave shielding and coating paints for touch panels, and are spreading rapidly, replacing existing electrically conductive polymer composite materials.

[0006] The unique properties of carbon nanotubes (CNTs) have the potential to influence innovation in diverse application fields, and it can be expected that various product innovations utilizing CNTs will emerge in these fields in the future. In fact, the lightweight and high-strength properties of carbon fibers are driving increased demand in civil engineering fields such as building materials, concrete structures, and seismic reinforcement, as well as in alternative energy fields such as compressed natural gas (CNG) tanks, wind turbine blades, centrifugal rotors, and flywheels.

[0007] Furthermore, the unique properties of graphene, a nanocarbon material, make it a material that, like CNTs, is expected to bring innovation to diverse application fields. While CNTs have a linear structure, graphene has a plate-like structure, and like CNTs, demand for it is increasing in a variety of fields. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] Conventional technology involved adding carbon nanoparticles separately to the positive and negative electrode slurry processes to ensure their conductivity. Failure to achieve a uniform conductive slurry resulted in reduced battery performance. Overcoming this limitation, directly coating the active material with a carbon nanoparticle slurry ensures more uniform conductivity and reduces resistance compared to batteries made using conductive slurry alone, resulting in lower surface resistance and superior battery life. [Means for solving the problem]

[0009] A carbon nanoparticle coating method may include the steps of: 1) mixing a dispersant, a first solvent, and a carbon nanomaterial to produce a dispersion; 2) homogenizing the carbon nanoparticles in the dispersion through a dispersion process; 3) stirring the dispersion and the material to be coated; and 4) adding a solution containing an ionic compound to coat the surface of the material to be coated with the carbon nanoparticles.

[0010] The aforementioned dispersant can be manufactured by selecting at least one from the group consisting of hydrogenated nitrile rubber, polyvinyl pyrrolidone, poly(acrylic acid), polyacrylonitrile, and polyacrylaide.

[0011] The first solvent can be prepared by selecting at least one from the group consisting of water (H2O), methanol (Methanol), ethanol (Ethanol), n-methylpyrrolidone, N,N-dimethylformamide, and dimethyl sulfoxide.

[0012] The carbon nanomaterial can be manufactured by selecting at least one from the group consisting of carbon nanotubes, carbon fibers, graphene, and carbon black.

[0013] The aforementioned ionic compound can be one selected from ionic compounds composed of salts of Group 1 elements and halogen elements.

[0014] The material to be coated can be one or more selected from the following: battery cathode materials such as lithium cobalt manganese, lithium iron phosphate, lithium cobalt oxide, and nickel cobalt aluminum; battery anode materials such as silicon-carbon composite (Si-C composite), silicon oxide (SiOx), silicon alloy, and MG-Si (metallurgical-grade silicon); heat dissipation materials such as aluminum oxide (Al2O3), barium nitride (Ba3N2), and porous glass (Glass bubble); and multilayer ceramic capacitors (MLCCs) such as barium titanate (BaTiO3), nickel metal powder, and copper metal powder.

[0015] The carbon nanoparticle coating method may further include the step of adding a second solvent and stirring it with the substance to be coated.

[0016] The second solvent can be prepared by selecting at least one from the group consisting of methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, acetate ether, butyl acetate, and amyl acetate.

[0017] The carbon nanoparticle coating method may further include the step of removing excess liquid from the material to be coated using a filter press and agglomerating it to produce a filter cake.

[0018] The carbon nanoparticle coating method may further include a step of drying the filter cake at 50°C to 150°C. [Effects of the Invention]

[0019] According to the present invention, by adding a solution composed of salts of Group 1 elements and halogen elements, the adsorption capacity of carbon nanoparticles can be increased, making it possible to obtain an active material uniformly coated with carbon nanomaterials, and the movement of lithium ions can be improved by ensuring improved conductivity.

[0020] In addition, the carbon structure network layer can ensure the electrical and chemical safety within the metal oxide, and can obtain the effect of suppressing irreversible reactions and side reactions with the electrolyte that may occur during the charge and discharge process.

[0021] If a carbon nanomaterial is coated on a heat dissipation material such as alumina (Al2O3) and boron nitride (BN), a high thermal conductivity can be obtained for the existing heat dissipation characteristics, so the heat dissipation characteristics can be enhanced.

Brief Description of the Drawings

[0022] [Figure 1] It is a flowchart of a carbon nanoparticle coating method according to an embodiment of the present invention. [Figure 2] It is a SEM image for confirming carbon nanotubes coated on the NCM surface using the coating method of the present invention. [Figure 3] It is a SEM image for confirming carbon nanotubes coated on the Si surface using the coating method of the present invention.

Modes for Carrying Out the Invention

[0023] The carbon nanoparticle coating method can include: 1) a step of mixing a dispersant, a first solvent, and a carbon nanomaterial to produce a dispersion; 2) a step of homogenizing the carbon nanoparticles in the dispersion through a dispersion process; 3) a step of stirring the dispersion and the coating target substance; and 4) a step of adding a solution containing an ionic compound to coat the carbon nanoparticles on the surface of the coating target substance.

[0024] The step 1) of mixing a dispersant, a first solvent, and a carbon nanomaterial to produce a dispersion can include a ball milling process.

[0025] Specifically, if a wet ball milling process is included, the dispersant, the first solvent, and the carbon nanomaterial can be mixed and then the dispersion can be produced at room temperature through the ball milling process. If a dry ball milling process is included, carbon nanotube particles can be produced from the carbon nanomaterial through the ball milling process, and then the dispersant and solvent can be mixed to produce the dispersion.

[0026] Furthermore, the step of mixing the dispersant, the first solvent, and the carbon nanomaterial to produce a dispersion may include a homogenization step.

[0027] The step of mixing the dispersant, the first solvent, and the carbon nanomaterial to produce a dispersion may include, but is not limited to, the ball milling step and the homogenization step.

[0028] The aforementioned dispersant can be manufactured by selecting at least one from the group consisting of hydrogenated nitrile rubber, polyvinyl pyrrolidone, poly(acrylic acid), polyacrylonitrile, and polyacrylaide.

[0029] The first solvent can be prepared by selecting at least one from the group consisting of water (H2O), methanol (Methanol), ethanol (Ethanol), n-methylpyrrolidone, N,N-dimethylformamide (34N,N-Dimethylformamide), and dimethyl sulfoxide.

[0030] The carbon nanomaterial can be manufactured by selecting at least one from the group consisting of carbon nanotubes, carbon fibers, graphene, and carbon black.

[0031] The dispersion step may be a step of homogenizing the carbon nanoparticles in the dispersion through a high-pressure disperser or an ultrasonic disperser.

[0032] In one embodiment, the dispersion step allows for the uniform dispersion of carbon nanoparticles in the dispersion liquid through high-pressure dispersion.

[0033] In one embodiment, the dispersion step allows for the uniform dispersion of carbon nanoparticles in the dispersion liquid through ultrasonic dispersion.

[0034] The step of stirring the dispersion and the substance to be coated can be performed at a speed of 500 to 5,000 rpm to ensure uniform coating of carbon nanoparticles.

[0035] The aforementioned ionic compound can be one selected from ionic compounds composed of salts of Group 1 elements and halogen elements.

[0036] Specifically, the ionic compound can be one or more selected from the group consisting of lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), sodium bromide (NaBr), potassium chloride (KCl), and potassium bromide (KBr).

[0037] Adding the aforementioned ionic compound has the effect of enhancing the coating and adsorption capabilities of carbon nanoparticles in the process of coating and adsorbing a dispersion of carbon nanoparticles onto the surface of the material to be coated.

[0038] The material to be coated can be a metal.

[0039] The material to be coated can be a ceramic.

[0040] The material to be coated can be one or more selected from battery positive electrode material, battery negative electrode material, heat dissipation material, and multilayer ceramic capacitor.

[0041] Specifically, the material to be coated can be one or more selected from the following: battery cathode materials such as lithium cobalt manganese, lithium iron phosphate, lithium cobalt oxide, and nickel cobalt aluminum; battery anode materials such as silicon-carbon composite (Si-C Composite), silicon oxide (SiOx), silicon alloy, and MG-Si (metallurgical-grade silicon); heat dissipation materials such as aluminum oxide (Al2O3), barium nitride (Ba3N2), and porous glass (Glass bubble); and multilayer ceramic capacitors (MLCCs) such as barium titanate (BaTiO3), nickel metal powder, and copper metal powder.

[0042] A carbon nanomaterial coating method may further include: 1) a step of mixing a dispersant, a first solvent, and a carbon nanomaterial to produce a dispersion; 2) a step of homogenizing the carbon nanoparticles in the dispersion through a dispersion process; 3) a step of stirring the dispersion and the material to be coated; 4) a step of adding an aqueous solution containing an ionic compound to coat the carbon nanoparticles on the surface of the material to be coated; and 5) a step of adding a second solvent and stirring it with the material to be coated.

[0043] The reason for adding the second solvent is that the material coated with carbon nanoparticles can undergo aggregation, and the solvent minimizes this aggregation.

[0044] The second solvent can be prepared by selecting at least one polar solvent from methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, acetate ether, butyl acetate, and amyl acetate.

[0045] The second solvent can be added in an amount of 50 to 500 parts by weight per 100 parts by weight of the carbon nanoparticle dispersion.

[0046] A carbon nanomaterial coating method may further include: 1) a step of mixing a dispersant, a first solvent, and a carbon nanomaterial to produce a dispersion; 2) a step of homogenizing the carbon nanoparticles in the dispersion through a dispersion process; 3) a step of stirring the dispersion and the material to be coated; 4) a step of adding an aqueous solution containing an ionic compound to coat the surface of the material to be coated with the carbon nanoparticles; 5) a step of adding a second solvent and stirring it with the material to be coated; and 6) a step of removing excess liquid from the material to be coated using a filter press and agglomerating it to produce a filter cake.

[0047] The process may further include a step of grinding the aggregate, from which the excess liquid has been removed, using a grinder or mixer.

[0048] The filter press may be a device equipped with a filter cloth and a membrane filter.

[0049] The filter cloth may have a fore size of 0.001 to 0.30 mm.

[0050] The filter press can be a device capable of producing a pressure of 1 to 10 bar.

[0051] A carbon nanomaterial coating method may further include the steps of: 1) mixing a dispersant, a first solvent, and a carbon nanomaterial to produce a dispersion; 2) homogenizing the carbon nanoparticles in the dispersion through a dispersion process; 3) stirring the dispersion and the material to be coated; 4) adding an aqueous solution containing an ionic compound to coat the surface of the material to be coated with the carbon nanoparticles; 5) adding a second solvent and stirring it with the material to be coated; 6) removing excess liquid from the material to be coated using a filter press to agglomerate it and produce a filter cake; and 7) drying the filter cake at 50°C to 150°C.

[0052] Manufacturing Example 1: Production of Carbon Nanotube Dispersion The step of adjusting the particle size of the carbon nanotubes to match the particle size D50 5 μm of the target material to be coated (NCM or Si) was performed through a ball mill or homogenization process.

[0053] In the case of a wet ball mill, a carbon nanotube dispersion with a D50 of 5 μm was produced by dissolving 1 g of hydrogenated nitrile rubber (HNBR) as a dispersant in 98 g of N-methylpyrrolidone (NMP), adding 1 g of carbon nanotubes, and 80 g of 3 pi zirconia balls, and rotating the mixture at 500 rpm for 12 hours at room temperature. The zirconia balls were removed from the produced carbon nanotube dispersion, and this was then processed twice in a high-pressure disperser using a 100 μm diamond cell at a pressure of 1,500 MPa to produce another carbon nanotube dispersion.

[0054] In the case of a dry ball mill, 7 kg of 3-ply zirconia balls were added, 150 g of carbon nanotubes were added, and the process was carried out at 600 rpm for 30 minutes to produce D50 5 μm carbon nanotube particles. These particles were then placed in a solvent containing 1 g of dispersant (HNBR) dissolved in 98 g of NMP, and the process was carried out twice in a high-pressure disperser using a 100 μm diamond cell at a pressure of 1,500 MPa to produce a carbon nanotube dispersion.

[0055] Manufacturing Example 2: Production of Graphene Dispersion The step of adjusting the particle size of the graphene to match the particle size D50 5 μm of the object to be coated (NCM or Si) utilized a ball mill or homogenization process.

[0056] In the case of a wet ball mill, a graphene dispersion with a D50 of 5 μm was produced by dissolving 1 g of hydrogenated nitrile rubber (HNBR) as a dispersant in 98 g of NMP, adding 1 g of graphene, and then adding 80 g of 3-pi zirconia balls and rotating the mixture at room temperature at 1,000 rpm for 10 hours.

[0057] The zirconia balls were removed from the manufactured graphene dispersion, and this was then processed three times in a high-pressure disperser using a 200 μm diamond cell at a pressure of 1,000 MPa to produce the graphene dispersion.

[0058] In the case of a dry ball mill, 7 kg of 3-ply zirconia balls were placed in a container, 100 g of graphene was added, and the process was carried out at 700 rpm for 25 minutes to produce D50 5 μm graphene particles. These particles were then placed in a solvent containing 1 g of dispersant (HNBR) dissolved in 98 g of NMP, and the process was carried out three times in a high-pressure disperser using a 200 μm diamond cell at a pressure of 1,000 MPa to produce a graphene dispersion.

[0059] Example 1. Carbon nanotube coating 25 g of the carbon nanotube dispersion produced in Production Example 1 and 100 g of the coating material NCM to be coated were homogenized and mixed. The mixture was stirred for 10 minutes at 1,000-3,000 rpm using homogenization or a powerful stirrer, and 0.05 g of LiCl was added to coat the surface of the carbon nanotubes.

[0060] Since carbon nanotube-coated materials undergo aggregation, 100g each of NMP (which can dissolve aggregation) and EtOH (which has a large polarity difference) were added and stirred. This mixture was then placed in a filter press to produce a filter cake.

[0061] During the filter pressing process, a 0.001mm filter cloth was used, and the process was carried out at a pressure of 4 bar. The manufactured filter cake was dried at 120°C, and the dried cake was crushed to produce the final product.

[0062] Example 2. The procedure was carried out in the same manner as in Example 1, but 50 g of carbon nanotube dispersion was used.

[0063] Example 3. The procedure was carried out in the same manner as in Example 1, but 100 g of carbon nanotube dispersion was used.

[0064] Example 4. Graphene coating 25 g of the graphene dispersion produced in Production Example 2 was uniformly mixed with 100 g of the NCM coating material to be coated. The mixture was stirred for 10 minutes at 1,000-3,000 rpm using homogenization or a powerful stirrer, and 0.05 g of LiCl was added to coat the surface of the graphene.

[0065] Since the graphene-coated material undergoes aggregation, 100g each of NMP (which can dissolve aggregation) and EtOH (which has a large polarity difference) were added and stirred, and this mixture was placed in a filter press to produce a filter cake.

[0066] During the filter pressing process, a 0.001mm filter cloth was used, and the process was carried out at a pressure of 4 bar. The manufactured filter cake was dried at 120 degrees Celsius, and the dried cake was then crushed to produce the final product.

[0067] Example 5. The procedure was carried out in the same manner as in Example 4, but 50 g of graphene dispersion was used.

[0068] Example 6. The procedure was carried out in the same manner as in Example 4, but 100 g of graphene dispersion was used.

[0069] Comparative Example 1. The procedure was carried out in the same manner as in Example 1, but without using any of the carbon nanotube dispersion or graphene dispersion, a bare state NCM cathode active material was used.

[0070] Comparative Example 2. The procedure was carried out in the same manner as in Example 1, but without using a LiCl solution for coating.

[0071] Comparative Example 3. The procedure was carried out in the same manner as in Example 4, but without using a LiCl solution for coating.

[0072] Example 7. Cathode Slurry Manufacturing A cathode slurry was prepared using the NCM acquired in Examples 1 to 6 and Comparative Examples 1 to 3. The method is as follows.

[0073] A first mixture was formed by mixing PVDF, a binder, with NMP, a solvent. Subsequently, a second mixture was formed by mixing the first mixture with carbon black. Then, a positive electrode slurry was produced by mixing the second mixture with NCM, a positive electrode active material. The solid content of the positive electrode slurry was 60% by weight. The weight ratio of the positive electrode active material, conductive material, and binder in the positive electrode slurry was 96:2:2.

[0074] Example 8. Si coating 25 g of the carbon nanotube dispersion produced in Production Example 1 was uniformly mixed with 100 g of the Si material to be coated. The mixture was stirred for 10 minutes at 1,000-3,000 rpm using homogenization or a powerful stirrer, and 0.05 g of LiCl was added to coat the surface of the carbon nanotubes.

[0075] Since carbon nanotube-coated materials undergo aggregation, 100g each of NMP (which can dissolve aggregation) and EtOH (which has a large polarity difference) were added and stirred, and this mixture was placed in a filter press to produce a filter cake.

[0076] During the filter pressing process, a 0.001mm filter cloth was used, and the process was carried out at a pressure of 4 bar. The manufactured filter cake was dried at 120 degrees Celsius, and the dried cake was then crushed to produce the final product.

[0077] Example 9. The procedure was carried out in the same manner as in Example 8, but 50 g of carbon nanotube dispersion was used.

[0078] Example 10. 25 g of the graphene dispersion produced in the above production example 2 and 100 g of the Si material to be coated were uniformly mixed. The mixture was stirred for 10 minutes at 1,000-3,000 rpm using homogenization or a powerful stirrer, and 0.05 g of LiCl was added to coat the surface of the graphene.

[0079] Since the graphene-coated material undergoes aggregation, 100g each of NMP (which can dissolve aggregation) and EtOH (which has a large polarity difference) were added and stirred, and this mixture was placed in a filter press to produce a filter cake.

[0080] During the filter pressing process, a 0.001mm filter cloth was used, and the process was carried out at a pressure of 4 bar. The manufactured filter cake was dried at 120 degrees Celsius, and the dried cake was then crushed to produce the final product.

[0081] Example 11. The procedure was carried out in the same manner as in Example 10, but 50 g of graphene dispersion was used.

[0082] Comparative Example 4. The procedure was carried out in the same manner as in Example 8, but bare Si was used instead of using both the carbon nanotube dispersion and the graphene dispersion.

[0083] Comparative Example 5. The procedure was carried out in the same manner as in Example 8, but without using a LiCl solution for coating.

[0084] Comparative Example 6. The procedure was carried out in the same manner as in Example 10, but the coating was carried out without using a LiCl solution.

[0085] Example 12. Negative electrode slurry production A negative electrode slurry was prepared using the Si negative electrode active materials acquired in Examples 8 to 11 and Comparative Examples 4 to 6. A first mixture was formed by mixing a conductive material dispersion, carbon black, and Si, which is a silicon-based active material. Subsequently, a second mixture was formed by mixing the first mixture with artificial soot. Subsequently, a third mixture was formed by mixing the second mixture with water, which is a solvent, and CMC, which is a thickener. Subsequently, a negative electrode slurry was prepared by mixing the third mixture with styrene-butadiene rubber (SBR), which is a binder. In the negative electrode slurry, the weight ratio of the negative electrode active material (artificial soot: Si = 86.39:9.61 by weight), conductive material (carbon black: single-walled carbon nanotube = 0.96:0.04 by weight), thickener, and binder was 96:1:1.7:1.3.

[0086] Experimental Example 1: Surface Resistance Measurement The positive electrode slurry produced according to Example 7 was coated onto aluminum foil using a 150 μm blade. The coated aluminum foil was dried at 120°C for 30 minutes to produce test specimens. Each test specimen was measured using a surface measuring instrument (ST-4).

[0087] Table 1 below is a diagram showing the surface resistance measurements of positive electrode slurries manufactured using the acquired NCM in Examples 1 to 6 and Comparative Examples 1 to 3.

[0088] [Table 1]

[0089] Experimental Example 2. Evaluation of discharge capacity using discharge C rate The positive electrode slurry produced in Example 7 was applied to an aluminum current collector with a thickness of 20 μm, and then vacuum-dried at 120°C for 10 hours to produce the positive electrode. The loading amount of the produced positive electrode was 8.8 mg / cm². 2 The total thickness was 54 μm. 1.76 cm 2 A circularly cut lithium (Li) metal thin film was used as the negative electrode.

[0090] A half-cell in the form of a CR-2032 coin cell was manufactured by injecting an electrolyte (ethylene carbonate (EC):dimethyl carbonate (DMC):diethyl carbonate (DEC) = 3:4:3 (bulk ratio)) and lithium hexafluorophosphate (LiPF 61 mol) between the positive and negative electrodes via a porous polyethylene separation membrane.

[0091] Within a voltage range of 3.0V to 4.25V, the charge rate was fixed at 0.5C after five 0.5C charge / discharge cycles, while the discharge rate was increased and the discharge capacity was measured. After increasing to 5C, the discharge efficiency of the positive electrode was evaluated while returning to 0.5C.

[0092] Table 2 below is a diagram showing the results of measuring the discharge capacity using positive electrode slurries manufactured using the acquired NCM described in Comparative Examples 1 to 3 and Examples 1 to 6.

[0093] [Table 2]

[0094] Referring to Table 2, when the active material is not coated with NCM (Comparative Example 1), high surface resistance is achieved by using carbon black to ensure conductivity, and in actual coin cell test results, performance deteriorates with a high C-rate. When halogen element salts are not used (Comparative Examples 2 and 3), the carbon nanomaterials intended to be coated on the active material are not uniformly adsorbed, and the surface resistance value is not particularly different from Comparative Example 1, while the C-rate results show slightly better efficiency than Comparative Example 1.

[0095] Furthermore, Examples 1 to 6 confirmed that when coating using halogen element salts, the battery resistance and C-rate characteristics of lithium-ion secondary batteries can be improved by adjusting the ratio of carbon nanomaterials to NCM active materials.

[0096] Experimental Example 3. Electrochemical Evaluation and Characterization The negative electrode slurry produced in Example 12 was coated onto a copper current collector, and then dried at 100°C for 12 hours to produce the cathode. 1.76 cm 2 A circular, cut lithium metal thin film was used as the positive electrode.

[0097] Coin cells were manufactured by injecting an electrolyte (ethylene carbonate (EC):ethyl methyl carbonate (EMC) = 3:7 (bulk ratio)), lithium hexafluorophosphate (LiPF 61 mol), and vinylidene carbonate (VC) content of 1.0 wt% by weight of the electrolyte between the positive and negative electrodes via a porous polyethylene separation membrane.

[0098] The cycle characteristics of the Si-based batteries obtained in Examples 8 to 10 and Comparative Examples 4 to 6 were evaluated, and the results were summarized by Formation and shown for the post-life expansion rate.

[0099] Specifically, the following conditions were used to perform charging and discharging on each battery.

[0100] 1 to 2 cycles: Charging was carried out with a static current of 0.1C, and discharging was performed with a static current of 0.1C until the voltage reached 1.5V.

[0101] 3 to 50 cycles: Charging was carried out with a static current of 0.5C, and discharge was performed with a static current of 0.5C until the voltage reached 1.0V.

[0102] Table 3 below shows the evaluation of the life characteristics of the negative electrode slurries produced by Comparative Examples 4 to 6 and Examples 8 to 11.

[0103] [Table 3]

[0104] Table 4 below is a diagram showing the loading, average density, average volume, average efficiency, and post-life expansion rate evaluation of the negative electrode slurries produced by Comparative Examples 4 to 6 and Examples 8 to 11.

[0105] [Table 4]

[0106] Referring to Table 4 above, when halogen group element salts are not used (Comparative Examples 5 to 6), a decrease in the lifetime characteristics of bare Si (Comparative Example 4) is observed, and a high expansion rate is shown in the expansion rate after lifetime characteristic evaluation.

[0107] Si anode active materials coated with 0.25% carbon nanomaterial (Examples 8 to 10) showed a slight improvement in lifetime characteristics, but exhibited a high expansion rate. Si alloy anode active materials coated with 0.5% carbon nanomaterial (Examples 9 to 11) showed high lifetime characteristics and exhibited a lower expansion rate even after lifetime characteristic evaluation.

[0108] This study demonstrates that by adjusting the content of carbon nanomaterials using halogen element salts, the lifespan characteristics of lithium-ion secondary batteries can be improved even at the negative electrode.

Claims

1. 1) A step of preparing a dispersion by mixing a dispersant, a first solvent, and a carbon nanomaterial, wherein the dispersant is hydrogenated nitrile rubber and the first solvent is N-methylpyrrolidone (NMP), 2) A step of homogenizing the carbon nanoparticles in the dispersion through a dispersion process, 3) A step of stirring the dispersion and the substance to be coated, wherein the substance to be coated is lithium nickel cobalt manganese oxide (NCM) or silicon (Si), 4) A step of coating the surface of the material to be coated with carbon nanoparticles by adding a solution containing an ionic compound, wherein the ionic compound is lithium chloride (LiCl), 5) A step in which, after the coating step, a second solvent is added and stirred with the substance to be coated, wherein the second solvent is ethanol. A method for coating carbon nanoparticles, including the following:

2. The carbon nanomaterial is manufactured by selecting at least one material from the group consisting of carbon nanotubes, carbon fibers, graphene, and carbon black. The carbon nanoparticle coating method according to claim 1.

3. 6) The step of removing excess liquid from the coating target material using a filter press and agglomerating it to produce a filter cake, The carbon nanoparticle coating method according to claim 1.

4. 7) Further comprising the step of drying the filter cake at 50°C to 150°C, The carbon nanoparticle coating method according to claim 3.

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