Wettability modification of carbon allotropes and wettability-modified carbon allotropes thereby

Abstract

The present invention relates to a method for modifying the wettability of a carbon allotrope, comprising the steps of: preparing a carbon allotrope; a step for preparing a solvent capable of inducing the generation of hydrophilic radicals or hydrophobic radicals; a step for bringing the carbon allotrope into contact with the solvent; a step of supplying energy to the solvent using an energy supply source; and a step of generating a hydrophilic radical or a hydrophobic radical of the solvent by the energy supplied to the solvent, the generated radical being bonded to the end of the carbon allotrope.

Description

Technical Field

[0001] This invention relates to a method for modifying the wettability of carbon allotropes and the carbon allotropes thereby achieving wettability modification. Background Technology

[0002] Supercapacitors can be broadly classified into pseudocapacitors and electric double-layer capacitors (EDLCs) based on their energy storage method. Pseudocapacitors store energy through redox reactions at the electrode-electrolyte interface, primarily using metal oxides or conductive polymers as electrode materials. Electric double-layer capacitors, as energy storage devices, employ a highly insulating separator between a pair of polarized electrodes made of carbon material. Capacitance is generated by forming an electric double layer between the electrodes and the electrolyte.

[0003] Electrochemical double-layer capacitors (ECL capacitors) are widely used in small, lightweight electrochemical energy storage devices, alongside batteries, due to their high output capacity and large energy storage capacity. Furthermore, among various energy storage devices, ECL capacitors are increasingly demonstrating their technological importance from both environmental and economic perspectives due to their use of environmentally friendly materials, long lifespan, and high charge / discharge efficiency. They are expected to be used as power supply devices for high-value-added equipment in military, aerospace, medical, and electric vehicle (HEV) applications.

[0004] Graphene has been widely adopted in recent years as a material for electrodes in electrochemical double-layer capacitors. Graphene possesses a two-dimensional sheet-like structure and exhibits excellent electrical, mechanical, physical, and chemical properties. In particular, its large specific surface area and outstanding electrical conductivity make it widely recognized as a suitable material for electrochemical double-layer capacitors.

[0005] However, for two-dimensional graphene, the strong π bonds between its graphene sheets lead to aggregation and re-stacking phenomena, which may reduce the excellent performance of graphene. Therefore, in order to achieve a wide voltage range while ensuring safety, it is necessary to develop electrochemical double-layer capacitors using nonpolar ionic liquid electrolytes. Moreover, in order to improve cost efficiency by achieving long cycle life and high ionic conductivity, it is necessary to develop electrochemical double-layer capacitors using polar aqueous electrolytes.

[0006] In this process, by appropriately adjusting the wettability of graphene, the active material used in the electrode, to match its polarity with that of the electrolyte, it is helpful to improve the charge storage capacity and rate performance of the electrochemical double-layer capacitor. This is because by introducing an active material with excellent wettability to the electrolyte, the surface area on which electrolyte ions can reach the electrode can be increased, thereby promoting ion diffusion inside the electrode.

[0007] This technique for adjusting the wettability of graphene can be used to maximize the performance of devices constructed using fluids with different polarities and graphene. In particular, besides supercapacitors, it holds promise for applications in various fields, including energy storage devices such as secondary batteries and fuel cells, as well as sensors and microfluidic transport devices.

[0008] On the other hand, with the development and increasing demand for mobile device technology in recent years, the demand for secondary batteries as energy sources has grown dramatically. Among secondary batteries, lithium secondary batteries, which have high energy density and high voltage, long cycle life, and low self-discharge rate, have been commercialized and are widely used. Typically, high-density electrodes are made by pressing electrode active material particles ranging in size from several micrometers to tens of micrometers into shape using a high-pressure press. As a result, the particles deform, the space between the particles decreases, and the electrolyte permeability is easily reduced.

[0009] To address these issues, highly conductive materials are used in electrode manufacturing. When conductive materials are used, they are dispersed between the compressed electrode active materials, maintaining a microporous structure between the active material particles. This facilitates electrolyte penetration and reduces internal electrode resistance due to their superior conductivity. Furthermore, while carbon black has traditionally been the primary conductive material, carbon-based conductive materials such as carbon nanofibers, carbon nanotubes, and planar graphene have become increasingly prevalent in recent years. By forming conductive pathways within the electrode, electrode resistance can be further reduced.

[0010] However, while carbon nanofibers and carbon nanotubes possess excellent electrical conductivity, their inherent properties make dispersion challenging. To address this issue, various dispersants have been proposed to improve the dispersibility of carbon nanofibers. However, dispersing carbon nanofibers at high concentrations in the dispersion medium can lead to problems due to increased viscosity.

[0011] Furthermore, carbon nanotubes are hydrophobic and aggregate when mixed with polar organic solvents or water. Simultaneously, van der Waals forces and π–π stacking between carbon nanotubes exacerbate this aggregation, potentially significantly reducing their dispersibility in organic solvents. Therefore, to improve the dispersibility of carbon nanotubes and solvents, attempts have been made to modify carbon nanotubes by introducing dispersants such as PVP (polyvinylpyrrolidone). However, when this method is applied to electrodes, the inclusion of a dispersant, which is an insulating material, can lead to a decrease in the electrode's electronic conductivity.

[0012] Therefore, there is an urgent need to study carbon materials that can adjust their wettability based on electrolyte polarity, as well as carbon materials that also possess excellent conductivity and dispersibility. Summary of the Invention

[0013] Technical problems to be solved One aspect of this invention is to provide a method for modifying the wettability of carbon allotropes using an energy supply source.

[0014] Another aspect of the present invention aims to provide a wettability-modified carbon allotrope with excellent electrical conductivity and improved dispersion stability.

[0015] Technical solution A method for modifying the wettability of a carbon allotrope according to an embodiment of the present invention includes: a step of preparing a carbon allotrope; a step of preparing a solvent capable of inducing the generation of hydrophilic or hydrophobic free radicals; a step of contacting the carbon allotrope with the solvent; a step of supplying energy to the solvent using an energy supply source; and a step of generating hydrophilic or hydrophobic free radicals of the solvent using the energy supplied to the solvent, wherein the generated free radicals are bonded to the ends of the carbon allotrope.

[0016] The carbon allotrope can be composed of sp2 hybridized carbon atoms.

[0017] The steps of preparing carbon allotropes may include: coating carbon allotropes onto porous foam; and drying the carbon allotropes coated onto the porous foam.

[0018] The energy source can be at least one selected from microwaves, electric fields, and plasma.

[0019] The solvent capable of inducing the generation of hydrophilic free radicals can be a solvent containing hydroxyl groups, and the solvent capable of inducing the generation of hydrophobic free radicals can be a solvent containing methyl or benzyl groups.

[0020] The solvent capable of inducing the generation of hydrophilic free radicals can be water, hydrogen peroxide, or a combination thereof, and the solvent capable of inducing the generation of hydrophobic free radicals can be acetone, toluene, or a combination thereof.

[0021] When the solvent is a solvent capable of inducing the generation of hydrophilic free radicals, the energy supply time for the step of supplying energy to the solvent using an energy supply source can be less than a few minutes.

[0022] The step of bonding the generated free radical to the end of the carbon allotrope can be carried out under at least one inert gas selected from the group consisting of argon, helium, xenon, krypton and neon.

[0023] When the solvent is a solvent capable of inducing the generation of hydrophobic free radicals, the energy supply time for the step of supplying energy to the solvent using an energy supply source can be less than a few minutes.

[0024] For the step of supplying energy to the solvent using an energy supply source, the water contact angle (WCA) can be adjusted according to the energy supply time.

[0025] The porous foam may include at least one porous foam selected from the group consisting of melamine foam, polyurethane foam, nickel foam, loofah sponge and natural foam.

[0026] The carbon allotrope may be selected from one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanofibers, graphene oxide, and two-dimensional graphene.

[0027] When the hydrophobic free radical bonds to the end of the carbon allotrope, the water contact angle (WCA) can be greater than 110°.

[0028] When the hydrophilic free radical bonds to the end of the carbon allotrope, the water contact angle (WCA) can be less than 50°.

[0029] The steps of supplying energy to the solvent using an energy supply source; and generating hydrophilic or hydrophobic free radicals of the solvent using the energy supplied to the solvent, wherein the generated free radicals bond to the ends of the carbon allotropes, may include: generating amino free radicals within the solvent using the energy supplied to the solvent; and the amino free radicals bonding to the ends of the carbon allotropes to obtain amino-modified carbon allotropes.

[0030] The content of amino groups in the modified carbon allotropes can be 1 to 7 wt% based on the total carbon allotropes.

[0031] The energy supply time for the energy supply step can be less than a few minutes.

[0032] The solvent capable of inducing the generation of amino radicals may include: a first solvent having hydroxyl groups; and a second solvent having amino groups.

[0033] The first solvent may be hydrogen peroxide or water, and the second solvent may be urea or melamine.

[0034] The solvent that can induce the generation of amino free radicals can be hydrogen peroxide and urea.

[0035] The hydrogen peroxide and urea can be mixed in a ratio of 1:1 to 1:4.

[0036] A method includes: contacting a hydrophilic carbon allotrope with a hydrophilic substituent at the end of the allotrope with a solvent capable of inducing the generation of a hydrophobic free radical; supplying energy to the solvent using an energy supply source; and converting the hydrophilic carbon allotrope into a hydrophobic carbon allotrope by the energy supplied to the solvent.

[0037] The energy supply time for the step of converting a hydrophilic carbon allotrope into a hydrophobic carbon allotrope can be less than a few minutes.

[0038] The energy source can be at least one selected from microwaves, electric fields, and plasma.

[0039] A method includes: contacting a hydrophobic carbon allotrope with a hydrophobic substituent at the end of the allotrope with a solvent capable of inducing the generation of a hydrophilic free radical; supplying energy to the solvent using an energy supply source; and converting the hydrophobic carbon allotrope into a hydrophilic carbon allotrope by the energy supplied to the solvent.

[0040] The energy supply time for the step of converting a hydrophobic carbon allotrope into a hydrophilic carbon allotrope can be less than a few minutes.

[0041] The energy source can be at least one selected from microwaves, electric fields, and plasma.

[0042] According to another embodiment of the present invention, the wettability-modified carbon allotrope exhibits hydrophobicity due to the hydrophobic substituent located at the end of the carbon allotrope.

[0043] The water contact angle (WCA) can be 110° or higher.

[0044] According to another embodiment of the present invention, the wettability-modified carbon allotrope exhibits hydrophilicity due to the hydrophilic substituent located at the end of the carbon allotrope.

[0045] The water contact angle (WCA) can be below 50°.

[0046] A method includes: a step of preparing a carbon allotrope; a step of preparing a solvent capable of inducing the generation of hydrophilic free radicals; a step of contacting the carbon allotrope with the solvent; a step of supplying energy to the solvent using an energy supply source; a step of generating hydrophilic free radicals within the solvent using the energy supplied to the solvent; and a step of the hydrophilic free radicals bonding to the ends of the carbon allotrope to obtain a carbon allotrope modified with hydrophilic groups.

[0047] The step of generating a hydrophilic free radical within the solvent by means of energy supplied to the solvent may include: generating an amino free radical within the solvent by means of energy supplied to the solvent; and the amino free radical being bonded to the end of the carbon allotrope to obtain an amino-modified carbon allotrope.

[0048] According to another embodiment of the present invention, a wettability-modified carbon allotrope is characterized in that the carbon allotrope is terminally bonded with an amino group.

[0049] The FT-IR spectrum of the modified carbon allotrope may include 1120 cm⁻¹. -1 and 3400cm -1 Absorption region of the band.

[0050] The size of the modified carbon allotrope particles can be 50 to 200 nm.

[0051] The water contact angle (WCA) of the modified carbon allotrope can be below 50°.

[0052] The carbon allotrope can be composed of sp2 hybridized carbon atoms.

[0053] The carbon allotrope may be selected from one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanofibers, graphene oxide, and two-dimensional graphene.

[0054] Beneficial effects According to an embodiment of the present invention, a carbon allotrope with wettability modification has the effect of ensuring long life and high electrostatic capacitance by reversibly changing the wettability of the carbon allotrope according to the polarity of the liquid electrolyte in an electrochemical double-layer capacitor.

[0055] According to an embodiment of the present invention, the wettability-modified carbon allotrope, due to its wettability modification, has active electron transfer and can further promote ion diffusion through its porous structure, thereby improving the performance of electronic and ion-related devices.

[0056] According to another embodiment of the present invention, the wettability-modified carbon allotrope can improve dispersion stability by modifying the ends of the carbon allotrope with amino groups.

[0057] According to another embodiment of the present invention, the wettability-modified carbon allotrope, due to the amino modification of the carbon allotrope ends, can construct an effective conductive network between active materials even in very small amounts, thereby improving conductivity. Attached Figure Description

[0058] Figure 1 This is a schematic diagram illustrating the wettability modification principle of microwave-mediated three-dimensional graphene manufactured according to an embodiment of the present invention.

[0059] Figure 2 a is the water contact angle (WCA) measurement result of three-dimensional graphene in a wettability-modified carbon allotrope according to an embodiment of the present invention, when energy is supplied under acetone-mediated conditions.

[0060] Figure 2 b is the water contact angle (WCA) measurement result of three-dimensional graphene in a water-mediated energy supply in a wettability-modified carbon allotrope according to an embodiment of the present invention.

[0061] Figure 3 The results are measurements of the water contact angle (WCA) of three-dimensional graphene in a carbon allotrope with wettability modification according to an embodiment of the present invention.

[0062] Figure 4 The water contact angle (WCA) of three-dimensional graphene is measured when energy is supplied to various organic solvents in a wettability-modified carbon allotrope according to an embodiment of the present invention.

[0063] Figure 5 This is a scanning electron microscope (SEM) image of three-dimensional graphene in a carbon allotrope with wettability modified according to an embodiment of the present invention, wherein the wettability is adjusted by supplying energy to different solvents.

[0064] Figure 6 a is a Fourier transform infrared spectrometer (FT-IR) measurement result of three-dimensional graphene according to an embodiment of the present invention.

[0065] Figure 6 b is the peak decomposition result of three-dimensional graphene according to an embodiment of the present invention, measured by Fourier transform infrared spectroscopy (FT-IR) based on solvent supply energy.

[0066] Figure 7 a is an energy diagram of the hydroxyl groups bonded to the ends of superhydrophilic three-dimensional graphene in a wettability-modified carbon allotrope according to an embodiment of the present invention.

[0067] Figure 7 b is an energy diagram of methyl groups bonded to the ends of superhydrophobic three-dimensional graphene in a wettability-modified carbon allotrope according to an embodiment of the present invention.

[0068] Figure 8 a is a cyclic voltammetry (CV) curve of a superhydrophobic three-dimensional graphene-based electrode in a wettability-modified carbon allotrope according to an embodiment of the present invention, when the electrode is in contact with a nonpolar or polar electrolyte.

[0069] Figure 8 b is a cyclic voltammetry (CV) curve of a superhydrophilic three-dimensional graphene-based electrode in a wettability-modified carbon allotrope according to an embodiment of the present invention, when the electrode is in contact with a nonpolar or polar solvent.

[0070] Figure 9 Figure a shows the galvanostatic charge-discharge (GCD) curves of a superhydrophobic three-dimensional graphene-based electrode in contact with a nonpolar (1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, EMIM-TFSI) electrolyte and a polar electrolyte (6M KOH) in a carbon allotrope with wettability modification according to an embodiment of the present invention, at different current densities.

[0071] Figure 9 Figure b shows the galvanostatic charge-discharge (GCD) curves of a superhydrophilic three-dimensional graphene-based electrode in contact with a nonpolar (EMIM-TFSI) electrolyte and a polar (6M KOH) electrolyte, according to an embodiment of the present invention, at different current densities.

[0072] Figure 9 c is based on Figure 9 b is measured using the constant current charge-discharge method (GCD) to calculate the discharge capacitance and to show a graph of capacitance as current density increases.

[0073] Figure 10 a is a wettability-modified carbon allotrope according to an embodiment of the present invention, in 0.2 A·g -1 The following is a constant current charge-discharge (GCD) curve of an electrochemical double-layer capacitor (EDLC) manufactured using a nonpolar (EMIM-TFSI) electrolyte after 5 cycles.

[0074] Figure 10b is a wettability-modified carbon allotrope according to an embodiment of the present invention, in 1 A·g -1 The following is a galvanostatic charge-discharge (GCD) curve of an electrochemical double-layer capacitor (EDLC) manufactured using a nonpolar (EMIM-TFSI) electrolyte after 5 cycles.

[0075] Figure 10 c represents 1A·g -1 The following is a graph showing the change in capacitance retention after 10,000 cycles of an electrochemical double-layer capacitor (EDLC) made with a nonpolar (EMIM-TFSI) electrolyte.

[0076] Figure 11 This is a schematic diagram of a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention.

[0077] Figure 12 The results are water contact angle (WCA) measurements of a wettability-modified carbon allotrope according to an embodiment and comparative example of the present invention.

[0078] Figure 13 The results are thermogravimetric analysis (TGA) results of carbon allotropes according to an embodiment and comparative example of the present invention.

[0079] Figure 14 The results are obtained by Fourier transform infrared spectroscopy (FT-IR) measurement of modified carbon allotropes according to an embodiment of the present invention.

[0080] Figure 15 The results are dynamic light scattering measurements of carbon allotropes according to an embodiment and comparative example of the present invention.

[0081] Figure 16 This is a schematic diagram illustrating the relationship between electron-donating groups (EDG) and electron-withdrawing groups (EWG) between a carbon allotrope modified with wettability according to an embodiment of the present invention and a solvent.

[0082] Figure 17 The results are based on the dispersion evaluation of carbon allotropes according to an embodiment and comparative example of the present invention.

[0083] Figure 18 It is a graph showing the capacity change of the button cells of Embodiment 2 and Comparative Examples 1, 3 and 5 according to the present invention after 150 charge-discharge cycles.

[0084] Figure 19 This is a graph showing the charge and discharge rates of the button cells according to Embodiment 2 and Comparative Examples 1, 3 and 5 at different rates.

[0085] Figure 20 The results are electrochemical impedance spectroscopy (EIS) measurements of a coin cell according to an embodiment and comparative example of the present invention.

[0086] Figure 21 It is a graph showing the capacity change of the button cells of Embodiment 2 and Comparative Examples 1 to 3 according to the present invention after 200 charge-discharge cycles.

[0087] Figure 22 This is a graph showing the charge and discharge rates of the button cells of Embodiment 2 and Comparative Examples 1 to 3 according to the present invention at different rates. Detailed Implementation

[0088] In this specification, the terms "first," "second," "third," etc., are used to describe various parts, components, regions, layers, and / or segments, but these parts, components, regions, layers, and / or segments should not be limited by these terms. These terms are only used to distinguish one part, component, region, layer, or segment from another part, component, region, layer, or segment. Therefore, without departing from the scope of the invention, the first part, component, region, layer, or segment described below can also be described as a second part, component, region, layer, or segment.

[0089] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. Unless the context clearly indicates otherwise, the singular forms used herein are intended to include the plural forms as well. The word "comprising" as used in the specification may specifically refer to a particular feature, domain, integer, step, action, element, and / or component, but does not exclude the presence or addition of other features, domains, integers, steps, actions, elements, components, and / or groups.

[0090] When one part is described as being on top of another part, there can be other parts directly on top of the other part or in between. When one part is described as being directly on top of another part, there are no other parts in between.

[0091] Although not otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in dictionaries should be interpreted as having the same meaning as disclosed in relevant technical literature and herein, and should not be interpreted in an idealized or overly formal sense.

[0092] Furthermore, unless otherwise specified, % means by weight, and 1 ppm is 0.0001 by weight.

[0093] In this specification, the term "combination thereof" as used in the Markush expression means a mixture or combination of one or more of the groups of constituent elements listed in the Markush expression, which means including any one or more of the groups of constituent elements.

[0094] Embodiments of the present invention will be described in detail below to enable those skilled in the art to implement the invention. However, the present invention can be implemented in various different ways and is not limited to the embodiments described herein.

[0095] Methods for modifying the wettability of carbon allotropes According to one embodiment of the present invention, carbon allotropes can be modified for wettability. In this specification, "wetting modification" refers to supplying energy to the carbon allotropes with a solvent capable of inducing the generation of hydrophilic, hydrophobic, or amino radicals. The carbon allotropes exhibit active electron transport and can further promote ion diffusion through their porous structure, thus more ideally improving the lifetime and capacitance of electronic and ion-related devices.

[0096] The wettability modification of carbon allotropes according to an embodiment of the present invention will be described in detail below.

[0097] A method for modifying the wettability of a carbon allotrope according to an embodiment of the present invention includes: a step of preparing a carbon allotrope; a step of preparing a solvent capable of inducing the generation of hydrophilic or hydrophobic free radicals; a step of contacting the carbon allotrope with the solvent; a step of supplying energy to the solvent using an energy supply source; and a step of generating hydrophilic or hydrophobic free radicals of the solvent using the energy supplied to the solvent, wherein the generated free radicals are bonded to the ends of the carbon allotrope.

[0098] In a method for modifying the wettability of a carbon allotrope according to an embodiment of the present invention, the carbon allotrope may be composed of sp2 hybridized carbon, but is not limited thereto; any carbon allotrope capable of wettability modification in this technical field may be used. The sp2 hybridized carbon allotrope may be at least one carbon allotrope selected from graphene, multilayer graphite, carbon nanotubes, fullerene (C60), Lonsdaleite, Buckminster fullerene, and buckyballs.

[0099] Figure 1 This is a schematic diagram illustrating how energy is supplied from an energy source to a solvent that induces hydrophilic or hydrophobic free radicals to regulate the wettability of three-dimensional graphene.

[0100] Reference Figure 1 It is known that three-dimensional graphene can achieve reversible wettability modification by supplying energy to solvents with hydrophilic or hydrophobic functional groups.

[0101] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the step of preparing the carbon allotropes may include: coating the carbon allotropes onto porous foam; and drying the carbon allotropes coated onto the porous foam. The drying step of the carbon allotropes may be performed in an oven, but is not limited thereto; any equipment capable of drying carbon allotropes in this technical field may be used.

[0102] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the energy supply source may be at least one selected from microwaves, electric fields and plasmas, but is not limited thereto; any energy source capable of supplying energy to carbon allotropes may be used.

[0103] Furthermore, after the step of coating the carbon allotrope onto the porous foam, a step of reducing the carbon allotrope via a hydrothermal reaction may be included. The hydrothermal reaction occurs at a temperature of 140 to 180°C, more specifically, 160°C. When the hydrothermal reaction temperature is below 140°C, the graphene oxide cannot be sufficiently reduced, making it difficult to supply energy via microwaves. When the hydrothermal reaction temperature is above 180°C, the porous foam will hydrolyze, potentially rendering it unusable in foam form.

[0104] Furthermore, the hydrothermal reaction takes place for 1 to 3 hours, more specifically 2 hours. If the hydrothermal reaction takes less than 1 hour, the graphene oxide cannot be fully reduced, making it difficult to supply energy via microwaves. If the hydrothermal reaction takes more than 3 hours, the porous foam will hydrolyze and may not be usable in foam form.

[0105] Three-dimensional graphene can be obtained by drying the carbon allotropes coated on porous foam. The drying process can be carried out using methods commonly used in the art and is not particularly limited. For example, freeze-drying, thermal drying, and spray drying can be employed.

[0106] In this specification, a solvent capable of generating polar free radicals is defined as a solvent that is compatible with hydrophilic solvents and whose solvent molecules include elements such as oxygen, sulfur, phosphorus, or nitrogen as substituents.

[0107] In this specification, a solvent capable of generating nonpolar free radicals is defined as a solvent that is compatible with hydrophobic solvents and that can promote the reaction with nonpolar compounds during the free radical generation process.

[0108] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the solvent capable of inducing the generation of hydrophilic free radicals may include, but is not limited to, solvents capable of inducing the generation of hydrophilic free radicals by receiving energy within the solvent. Specifically, solvents capable of generating polar free radicals may include electron-withdrawing groups (EWGs). Furthermore, solvents capable of generating polar free radicals may include water, ethanol, dimethyl sulfoxide, dimethylformamide, pyridine, acetic acid, hydrogen peroxide, or triethylamine, etc.

[0109] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the solvent capable of inducing the generation of hydrophobic free radicals may include, but is not limited to, solvents capable of inducing the generation of hydrophobic free radicals by receiving energy within the solvent. Specifically, the solvent capable of generating nonpolar free radicals may include electron-donating groups (EDGs). Furthermore, the solvent capable of generating nonpolar free radicals may include hexane, toluene, chloroform, dichloromethane, xylene, or benzene, etc.

[0110] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the solvent capable of inducing the generation of hydrophilic free radicals is a solvent having hydroxyl groups, and the solvent capable of inducing the generation of hydrophobic free radicals may be a solvent having methyl or benzyl groups, but is not limited thereto. Any solvent capable of inducing the generation of hydrophilic or hydrophobic free radicals in this technical field may be used.

[0111] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the solvent capable of inducing the generation of hydrophilic free radicals may be water, hydrogen peroxide, or a combination thereof, and the solvent capable of inducing the generation of hydrophobic free radicals may be acetone, toluene, or a combination thereof, but is not limited thereto. Any solvent capable of inducing the generation of hydrophilic or hydrophobic free radicals in this technical field may be used.

[0112] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, when the solvent is a solvent capable of inducing the generation of hydrophilic free radicals, the energy supply time for the step of supplying energy to the solvent using an energy supply source can be less than a few minutes, specifically less than 5 minutes, less than 3 minutes, less than 1 minute, less than 30 seconds, or less than 15 seconds. When the energy supply time meets the aforementioned range, based on the shorter energy supply time, wettability-modified carbon allotropes can be manufactured in real time as needed.

[0113] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the step of bonding the generated free radicals to the ends of the carbon allotropes can be carried out under at least one inert gas selected from the group consisting of argon, helium, xenon, krypton and neon.

[0114] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, when the solvent is a solvent capable of inducing the generation of hydrophobic free radicals, the energy supply time for the step of supplying energy to the solvent using an energy supply source can be less than a few minutes, specifically less than 10 seconds, less than 7 seconds, or less than 5 seconds, more specifically less than 2 to 5 seconds. When the energy supply time meets the aforementioned range, based on the shorter energy supply time, wettability-modified carbon allotropes can be manufactured in real time as needed.

[0115] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the water contact angle (WCA) can be adjusted according to the energy supply time for the step of supplying energy to the solvent using an energy supply source.

[0116] Figure 2 It is based on the water contact angle measurement results of the energy supply.

[0117] Reference Figure 2 It can be confirmed that for solvents capable of inducing the generation of hydrophobic free radicals, in the process of supplying energy to the solvent using an energy supply source to convert hydrophilic carbon allotropes into hydrophobic carbon allotropes, if energy is applied for 2 seconds, the water contact angle (WCA) is 147°, and if energy is applied for 5 seconds, the water contact angle (WCA) is 168°. As the energy irradiation time increases, the hydrophobicity of the carbon allotropes increases, thereby increasing the water contact angle.

[0118] In addition, refer to Figure 2 It can be confirmed that, for solvents capable of inducing the generation of hydrophilic free radicals, in the process of supplying energy to the solvent using an energy supply source to convert hydrophobic carbon allotropes into hydrophilic carbon allotropes, if energy is applied for 7 seconds, the carbon allotropes require 4.6 seconds to absorb water droplets; however, if energy is applied for 10 seconds, the carbon allotropes require only 0.13 seconds to absorb water droplets. The hydrophilicity gradually increases with increasing energy supply time. For these carbon allotropes, even when energy is supplied to solvents capable of inducing either hydrophobic or hydrophilic free radicals, the interconnected carbon allotrope network remains unchanged, and the porous structure formed by pyrolysis caused by the energy supply is also preserved. This structure can be confirmed using scanning electron microscopy (SEM).

[0119] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the porous foam may include at least one porous foam selected from the group consisting of melamine foam, polyurethane foam, nickel foam, loofah sponge and natural foam, but is not limited thereto; any porous foam that can be used in this technical field may be used.

[0120] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the carbon allotropes may be selected from one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanofibers, graphene oxide and two-dimensional graphene, but are not limited thereto. Any carbon allotropes that can be used as electrode materials in this technical field may be used.

[0121] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, when the hydrophobic free radical bonds to the end of the carbon allotropy, the water contact angle (WCA) can be 110° or higher, specifically 150° or higher. When the water contact angle meets the above range, it can be applied to fields requiring carbon allotropes to have good wettability with nonpolar solvents or low wettability with polar solvents. In summary, by modifying the wettability of carbon allotropes according to the present invention, they can be made to exhibit hydrophobicity, specifically superhydrophobicity.

[0122] In this specification, "superhydrophobic" can refer to a water contact angle of 150° or more.

[0123] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, when the hydrophilic radical bonds to the end of the carbon allotropy, the water contact angle (WCA) can be less than 50°, specifically 0 to 5°. When the water contact angle meets the above range, it can be applied to fields requiring carbon allotropes that have good wettability with polar solvents or low wettability with nonpolar solvents.

[0124] In summary, by modifying the wettability of the carbon allotrope according to the present invention, it can be made to exhibit hydrophilicity, specifically superhydrophilicity.

[0125] In this specification, "superhydrophilic" can refer to a water contact angle of less than 5°.

[0126] A method for modifying the wettability of a carbon allotrope according to an embodiment of the present invention includes: a step of preparing a carbon allotrope; a step of preparing a solvent capable of inducing the generation of hydrophilic free radicals; a step of contacting the carbon allotrope with the solvent; a step of supplying energy to the solvent using an energy supply source; a step of generating hydrophilic free radicals within the solvent using the energy supplied to the solvent; and a step of the hydrophilic free radicals bonding to the ends of the carbon allotrope to obtain a carbon allotrope modified with hydrophilic groups.

[0127] In a method for modifying the wettability of a carbon allotrope according to an embodiment of the present invention, the step of generating a hydrophilic free radical in the solvent by energy supplied to the solvent may include: generating an amino free radical in the solvent by energy supplied to the solvent; and the amino free radical bonding to the end of the carbon allotrope to obtain an amino-modified carbon allotrope.

[0128] Figure 11 This is a schematic diagram of a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention.

[0129] Reference Figure 11 It can be confirmed that amino radicals are formed by supplying energy to a solvent obtained by mixing urea and hydrogen peroxide in a 3:1 ratio, and these amino radicals are chemisorbed onto the ends of carbon nanotubes.

[0130] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the content of amino groups in the modified carbon allotropes, based on the total carbon allotropes, can be 1 to 7 wt%, specifically 1.3 to 4.5 wt%, and more specifically 1.8 to 2.5 wt%. When the content of amino groups meets the above range, the carbon allotropes, which have approximately one amino group bonded to each of approximately 17 carbon rings, exhibit excellent dispersion stability in the dispersion liquid. On the other hand, when the content of amino groups exceeds the above range, the carbon allotropes may aggregate, potentially leading to a decrease in dispersibility.

[0131] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the energy supply time of the energy supply step can be less than several minutes, specifically 1 second to 5 minutes, 1 second to 2 minutes, 1 second to 1 minute, or 5 seconds to 30 seconds, more specifically 8 seconds to 25 seconds, and even more specifically 10 seconds to 20 seconds. When the energy supply time meets the above range, amino radicals are generated in the solvent and bond with the carbon allotropes, thereby improving the dispersion stability of the dispersion. On the other hand, when the energy supply time exceeds the above range, problems such as damage and destruction of carbon allotropes and the formation of excessive defects may occur.

[0132] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the solvent capable of inducing the generation of amino radicals may include a first solvent having hydroxyl groups and a second solvent having amino groups, but is not limited thereto; any solvent capable of inducing the generation of amino radicals by receiving energy in this technical field may be used.

[0133] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the first solvent may be hydrogen peroxide or water, and the second solvent may be urea or melamine, but is not limited thereto; any solvent having hydroxyl groups as the first solvent or having amino groups as the second solvent may be used. Furthermore, ammonia may also be used as the second solvent.

[0134] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the solvent capable of inducing the generation of amino radicals may be hydrogen peroxide and urea, but is not limited thereto; any solvent capable of generating amino radicals by receiving energy may be used.

[0135] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, hydrogen peroxide and urea can be mixed in a ratio of 1:1 to 1:4, specifically 1:1.5 to 1:3.5, and more specifically 1:2 to 1:3. When the ratio of hydrogen peroxide to urea meets the above range, the ammonia generated during the pyrolysis of urea undergoes a dehydrogenation reaction with the hydroxyl radicals generated during the pyrolysis of hydrogen peroxide, thereby appropriately generating amino radicals in the solvent. On the other hand, when the ratio of hydrogen peroxide to urea exceeds the above range, there may be a risk of undesirable excessive generation of free radicals leading to side reactions, and problems such as hydroxyl modification and amino substitution of carbon allotropes may occur.

[0136] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the carbon allotropes may include single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanofibers, graphene or graphene oxide, but are not limited thereto. Any carbon allotropes that can be modified by receiving energy in this technical field may be used.

[0137] A method for modifying the wettability of a carbon allotrope according to an embodiment of the present invention includes: contacting a hydrophilic carbon allotrope with hydrophilic substituents located at the ends of the carbon allotrope with a solvent capable of inducing the generation of hydrophobic free radicals; supplying energy to the solvent using an energy supply source; and converting the hydrophilic carbon allotrope into a hydrophobic carbon allotrope by the energy supplied to the solvent.

[0138] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the energy supply time for the step of converting a hydrophilic carbon allotrope into a hydrophobic carbon allotrope can be less than several minutes, specifically less than 5 minutes, less than 3 minutes, less than 1 minute, or less than 10 seconds, more specifically less than 8 seconds. When the energy supply time meets the range, the hydrophilic carbon allotrope can be converted into a hydrophobic carbon allotrope. On the other hand, when the energy supply time exceeds the range, it may be difficult to adjust the wettability of the hydrophilic carbon allotrope.

[0139] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the energy supply source may be at least one selected from microwaves, electric fields and plasmas, but is not limited thereto. Any energy supply source that can be used as an energy supply source to modify the wettability of carbon allotropes in this technical field may be used.

[0140] A method for modifying the wettability of a carbon allotrope according to an embodiment of the present invention includes: contacting a hydrophobic carbon allotrope with a hydrophobic substituent located at the end of the carbon allotrope with a solvent capable of inducing the generation of hydrophilic free radicals; supplying energy to the solvent using an energy supply source; and converting the hydrophobic carbon allotrope into a hydrophilic carbon allotrope by the energy supplied to the solvent.

[0141] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the energy supply time for the step of converting a hydrophobic carbon allotrope into a hydrophilic carbon allotrope can be less than several minutes, specifically less than 1 minute, less than 40 seconds, less than 20 seconds, and more specifically less than 15 seconds. When the energy supply time meets the range, the hydrophobic carbon allotrope can be converted into a hydrophilic carbon allotrope. On the other hand, when the energy supply time exceeds the range, it may be difficult to adjust the wettability of the hydrophobic carbon allotrope.

[0142] In a method for modifying the wettability of carbon allotropes according to an embodiment of the present invention, the energy supply source may be at least one selected from microwaves, electric fields and plasmas, but is not limited thereto. Any energy supply source that can be used as an energy supply source to modify the wettability of carbon allotropes in this technical field may be used.

[0143] Wetting-modified carbon allotropes According to another embodiment of the invention, the wettability-modified carbon allotrope exhibits hydrophobicity because the hydrophobic substituent is located at the end of the carbon allotrope.

[0144] According to another embodiment of the present invention, the wettability-modified carbon allotrope has a water contact angle (WCA) of 110° or more, specifically a water contact angle (WCA) of 150° or more.

[0145] According to another embodiment of the invention, the wettability-modified carbon allotrope exhibits hydrophilicity because the hydrophilic substituent is located at the end of the carbon allotrope.

[0146] According to another embodiment of the present invention, the wettability-modified carbon allotrope has a water contact angle (WCA) of 50° or less, specifically 5° or less.

[0147] In the following description, the wettability-modified carbon allotropes of the present invention will be described with reference to the accompanying drawings.

[0148] Figure 2'a' represents the measured water contact angle (WCA) of three-dimensional graphene under acetone solvent-mediated energy supply, inducing the generation of hydrophobic free radicals. Even when irradiated with an energy supply source for only 2 seconds, three-dimensional graphene with hydrophilic free radicals bonded to acetone residues can be converted from hydrophilic to hydrophobic free radicals, with a maximum WCA of 168°C. The correlation between energy supply time and hydrophobicity is related to the degree of chemisorption of nonpolar methyl groups provided by acetone decomposition induced by the energy supply.

[0149] Figure 2 b represents the water contact angle (WCA) measurement of three-dimensional graphene powered by water. After treating the three-dimensional graphene foam with water vapor as a source of hydroxyl radicals and supplying energy for 7 seconds, the water contact angle (WCA) was 0°. Water-mediated energy supply requires a longer reaction time to achieve wettability conversion. Amphiphilic acetone is not hindered from approaching hydrophobic surfaces, while hydrophilic water may have difficulty approaching hydrophobic surfaces even in the steam state.

[0150] On the other hand, according to another embodiment of the present invention, the wettability-modified carbon allotrope is characterized in that an amino group is bonded to the end of the carbon allotrope. When the end of the carbon allotrope is bonded with an amino group, hydrogen bonds are formed due to the interaction between the carbonyl group of the N-methylpyrrolidone (NMP) solvent and the amino group at the end of the carbon allotrope. Furthermore, the amino group at the end of the carbon allotrope acts as an electron-donating group (EDG), and the carbonyl group in NMP acts as an electron-withdrawing group (EWG), thereby resulting in a stronger bond and interaction between the amino-modified carbon nanotube and NMP, which can improve the dispersion stability.

[0151] In a wettability-modified carbon allotrope according to yet another embodiment of the present invention, the FT-IR spectrum of the modified carbon allotrope may include 1120 cm⁻¹. -1 and 3400cm -1 The absorption region of the band. When the FT-IR spectrum satisfies the specified band, it indicates that the modified carbon allotrope contains N–H and C–N bonds.

[0152] In a wettability-modified carbon allotrope according to another embodiment of the present invention, the size of the modified carbon allotrope particles can be 50 to 200 nm, specifically 70 to 150 nm, and more specifically 80 to 120 nm. When the particle size of the modified carbon allotrope meets the range described above, the modified carbon allotrope can be uniformly dispersed in N-methylpyrrolidone (NMP). On the other hand, when the particle size of the modified carbon allotrope exceeds the range described above, the modified carbon allotrope may precipitate in N-methylpyrrolidone (NMP), potentially leading to a decrease in dispersibility.

[0153] In a wettability-modified carbon allotrope according to another embodiment of the present invention, the water contact angle (WCA) of the modified carbon allotrope may be 50° or less, specifically 30° or less, and more specifically 10° or less. When the water contact angle (WCA) meets the above range, a hydrophilic surface can be formed on the modified carbon allotrope, thereby improving the dispersibility to polar solvents. On the other hand, when the water contact angle (WCA) of the modified carbon allotrope exceeds the above range, the dispersibility to polar solvents may decrease because a suitable hydrophilic surface cannot be formed.

[0154] In a wettability-modified carbon allotrope according to another embodiment of the present invention, the carbon allotrope may be composed of sp2 hybridized carbon, but is not limited thereto; any material that can be modified to improve the dispersibility of the carbon allotrope in this technical field may be used.

[0155] In another embodiment of the present invention, the carbon allotrope modified for wettability can be one or more selected from single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanofibers, graphene oxide and two-dimensional graphene, but is not limited thereto. Any material that can be modified to improve the dispersibility of carbon allotropes in this technical field can be used.

[0156] Manufacturing supercapacitors The wettability-modified carbon allotrope manufactured according to the present invention can be used as an electrode material in supercapacitors. The basic structure of the supercapacitor may include electrodes consisting of a positive electrode and a negative electrode, and an electrolyte.

[0157] The supercapacitor includes: a negative electrode; a positive electrode arranged opposite to the negative electrode; and an electrolyte disposed between the negative electrode and the positive electrode and providing an ion migration channel, wherein at least one of the negative electrode and the positive electrode may include a carbon allotrope.

[0158] The electrolyte providing the ion migration channel can be a nonpolar electrolyte or a polar electrolyte. Nonpolar electrolytes may include, but are not limited to, at least one selected from 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI), 1-ethyl-3-methylimidazolium hexafluorophosphate (EMIM-PF6), and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIM-FSI), and any electrolyte suitable for use as a nonpolar electrolyte in this technical field. Polar electrolytes may include, but are not limited to, at least one selected from potassium hydroxide (KOH), sulfuric acid (H2SO4), and potassium chloride (KCl), and any electrolyte suitable for use as a polar electrolyte in this technical field.

[0159] The supercapacitor of this invention can be classified into electrochemical double-layer capacitors or pseudocapacitors based on its charge storage mechanism. In one specific embodiment, the supercapacitor of this invention can be an electrochemical double-layer capacitor. This supercapacitor utilizes the pseudocapacitive principle, which stores energy through a reversible Faraday oxidation / reduction reaction at the electrode-electrolyte interface. The electrochemical double-layer capacitor has a highly insulating separator arranged between a pair of polarized electrodes made of carbon material. Capacitance is generated by forming a double layer between the electrodes and the electrolyte, thereby increasing the energy storage capacity of the capacitor.

[0160] The present invention will be described in detail below through embodiments, but the following embodiments and experimental examples are only used to illustrate one form of the present invention, and the scope of the present invention is not limited to the following embodiments and experimental examples.

[0161] Methods of implementing the invention Example 1 1-1. Preparing three-dimensional graphene Cut the melamine foam into 1×1×1.5cm pieces. 3A cube was coated with a large amount of graphene oxide solution and then reduced at 160°C for 2 hours via a hydrothermal reaction. After overnight freeze-drying, three-dimensional graphene capable of reacting with microwaves was obtained. Microwave irradiation (2.54 GHz, 350 W) for 15 seconds in an inert gas (Ar) atmosphere, followed by carbonization, reduction, and nitrogen doping induced by arc formation, produced the hydroxyl-bonded superhydrophilic three-dimensional graphene of Example 1-1.

[0162] 1-2. Methods for modifying the wettability of superhydrophilic three-dimensional graphene To modify the superhydrophilic three-dimensional graphene obtained from Examples 1-1 into superhydrophobic three-dimensional graphene through wettability modification, the three-dimensional graphene from Examples 1-1 was contacted with acetone and then immediately dried in an oven. To achieve the chemisorption of methyl radicals, the superhydrophilic three-dimensional graphene with acetone residues was microwave-irradiated for up to 8 seconds, thereby converting it into superhydrophobic three-dimensional graphene.

[0163] 1-3. Methods for modifying the wettability of superhydrophobic three-dimensional graphene To modify the superhydrophobic three-dimensional graphene obtained from Examples 1-2 into superhydrophilic three-dimensional graphene through wettability modification, the three-dimensional graphene from Examples 1-2 was exposed to water vapor in an autoclave, and the superhydrophobic graphene with residual moisture was microwave irradiated for up to 10 seconds to adsorb hydroxyl radicals, thereby converting it into superhydrophilic three-dimensional graphene.

[0164] 1-4. Electrode Manufacturing Three-dimensional graphene samples from Examples 1-2 and 1-3 were prepared. The electrochemical performance of an electrochemical double-layer capacitor based on the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM-TFSI) was evaluated using a coin cell (CR2032). To prepare the working electrode, a mixture of 80 wt% polarity-tuned three-dimensional graphene, 10 wt% acetylene black, and 10 wt% polyvinylidene fluoride (PVDF) binder was used as the active material at a maximum concentration of 1.0 mg·cm⁻¹. -2 Mass coating on nickel (Ni) foam (100 μm thick, 1×1 cm²) 2 The electrode of an electrochemical double-layer capacitor is prepared by drying and pressing the electrode in a vacuum oven.

[0165] Example 2 2-1. Amine-modified carbon nanotubes for manufacturing A solvent containing a 3:1 mixture of urea and hydrogen peroxide, along with multi-walled carbon nanotubes (MWCNTs), was prepared. The MCCNTs were then contacted with the solvent and subjected to microwave irradiation for 10 to 20 seconds. The MCCNTs reacted with the microwaves to form plasma, which decomposed the solvent into amino radicals. These decomposed amino radicals were chemically adsorbed onto the ends of the carbon nanotubes, thus obtaining amino-wetting-modified carbon nanotubes.

[0166] 2-2. Manufacturing electrode paste The positive electrode active material (LFP, LiFePO4), the modified carbon nanotubes from Example 2-1, and the binder (PVDF, polyvinylidene fluoride) were formulated to a weight ratio of 8:1:1. Specifically, NMP solvent and the binder (PVDF) were dissolved at a weight ratio of 36.3:3.7 to obtain a binder solution. Carbon nanotubes were added to the binder solution, and after stirring for 3 hours, the mixture was ultrasonically treated for 20 minutes to disperse the modified carbon nanotubes from Example 1-1 in the binder solution. Subsequently, the positive electrode active material and the modified carbon nanotubes from Example 1-1 were mixed for 4 minutes using a Thinky mixer. The binder solution was added to the resulting solid mixture, and the mixture was mixed again to produce an electrode slurry for secondary batteries.

[0167] 2-3. Manufacturing button cells The electrode paste prepared in Example 2-2 was uniformly coated onto the electrode current collector (aluminum foil) using a doctor blade, so that the full-area loading density was approximately 3 to 4 mg / cm³. 2 The electrode current collector coated with electrode slurry was dried in a vacuum oven at 60°C for 6 hours to obtain the electrode. After rolling the electrode to approximately 70% of its original thickness, a coin cell was manufactured using the rolled electrode as the positive electrode and Li metal as the negative electrode.

[0168] Comparative Example 1 1-1. Carbon nanotubes Carbon nanotubes were prepared (manufacturer: Carbonnanotech, length: up to 10 μm, diameter: 5 to 15 nm).

[0169] 1-2. Manufacturing electrode paste Except that the carbon nanotubes of Comparative Example 1-1 were used in manufacturing the electrode paste, the electrode paste was manufactured using the same method as in Example 2-2.

[0170] 1-3. Manufacturing button cells Except for using the electrode slurry manufactured in Comparative Examples 1-2, coin cells were manufactured using the same method as in Examples 2-3.

[0171] Comparative Example 2 2-1. Single-walled carbon nanotubes Single-walled carbon nanotubes (manufacturer: Tuball, length > 5 μm, diameter: 1.6 nm) were prepared.

[0172] 2-2. Manufacturing electrode paste The electrode paste was prepared using single-walled carbon nanotubes from Comparative Example 2-1, with the weight ratio of NMP solvent to binder (PVDF) set to 97:2. Otherwise, the electrode paste was prepared using the same method as in Example 2-2.

[0173] 2-3. Manufacturing button cells Except for using the electrode paste manufactured in Comparative Example 2-2, coin cells were manufactured using the same method as in Example 2-3.

[0174] Comparative Example 3 3-1. Manufacturing carboxyl-modified carbon nanotubes Except for using a 3:1 mixture of formic acid and hydrogen peroxide as a solvent, the manufacturing method is the same as in Example 2-1. Carboxyl groups are chemically adsorbed onto the ends of carbon nanotubes to obtain carboxyl-modified carbon nanotubes.

[0175] 3-2. Manufacturing electrode paste Except for the use of the modified carbon nanotubes in Comparative Example 3-1, the electrode paste was prepared using the same method as in Example 2-2.

[0176] 3-3. Manufacturing button cells Except for using the electrode paste of Comparative Example 3-2, coin cells were manufactured using the same method as in Examples 2-3.

[0177] Comparative Example 4 4-1. Prepare carbon black (Super P) Carbon black (Super P, manufacturer: MTI, particle size > 20 μm) was prepared.

[0178] 4-2. Manufacturing electrode paste Except for using the carbon black (Super P) of Comparative Example 4-1, the electrode paste was prepared using the same method as in Example 2-2.

[0179] 4-3. Manufacturing button cells Except for using the electrode paste of Comparative Example 4-2, coin cells were manufactured using the same method as in Examples 2-3.

[0180] Reference Example 1 1-1. Manufacturing Methyl-Modified Carbon Nanotubes Except for the use of acetone as a solvent, the manufacturing method is the same as in Example 2-1. Methyl groups are chemically adsorbed onto the ends of carbon nanotubes to obtain methyl-modified carbon nanotubes.

[0181] 1-2. Manufacturing electrode paste Except for the use of methyl-modified carbon nanotubes as in Reference Example 1-1, the electrode paste was prepared using the same method as in Example 2-2.

[0182] 1-3. Manufacturing button cells Except for using the electrode paste of Reference Examples 1-2, coin cells were manufactured using the same method as in Examples 2-3.

[0183] Experimental Example 1: Measurement of Water Contact Angle (WCA) After a 10 μL water droplet was dropped onto the surface of a three-dimensional graphene or carbon nanotube according to an embodiment and comparative example of the present invention, the water contact angle (WCA) was measured three times using a Goniometer (FemtoBioMed intelligent dropper), and the average value of the measurements is then shown in the figure. Figure 2 , Figure 3 and Figure 12 middle.

[0184] Figure 2 a represents the water contact angle (WCA) measurement results of three-dimensional graphene irradiated with microwaves under the acetone solvent mediated by the induced generation of hydrophobic free radicals in Examples 1-2, with a maximum value of 168°C. The correlation between microwave irradiation time and hydrophobicity is related to the degree of chemisorption of nonpolar methyl groups provided by the microwave decomposition of acetone. Figure 2 b represents the water contact angle (WCA) measurement results of three-dimensional graphene irradiated with microwaves under water-mediated conditions in Examples 1-3, with a minimum value of 0°C.

[0185] Figure 3 The results pertain to the water contact angle measurement of the reversible wettability regulation of the three-dimensional graphene. With 10 alternating microwave treatments mediated by different solvents in Example 2 or Example 3, the water contact angle changed from 0° to 156–162°, indicating that the three-dimensional graphene can achieve reversible wettability regulation from hydrophilic to hydrophobic.

[0186] Reference Figure 12 The water contact angles (WCA) of Comparative Example 1-1 and Reference Example 1-1 were approximately 132° and 160°, respectively, exhibiting high hydrophobicity. However, the water contact angle (WCA) of the amino-bonded carbon nanotubes at the ends in Example 2-1 was 0°. Due to the formation of a superhydrophilic surface, the dispersibility to polar solvents can be improved.

[0187] Experimental Example 2: Solvent Analysis To achieve wettability modulation from superhydrophilic 3D graphene to superhydrophobic 3D graphene, superhydrophilic 3D graphene was reacted with ethanol and immediately dried in an oven. For chemisorption of methyl radicals, superhydrophilic 3D graphene with acetone residues was microwave-irradiated for a maximum of 8 seconds. However, ethanol directly induced the dehydration process without forming methyl radicals, therefore the hydrophobic radicals failed to bond to the ends of the 3D graphene. Furthermore, when microwave-irradiated with different organic solvents other than ethanol, the hydrophobic radicals also failed to bond to the ends of the 3D graphene. (See [reference needed]). Figure 4 .

[0188] Figure 4 This relates to the water contact angle (WCA) measurements of three-dimensional graphene supplied with energy to various organic solvents. Hydrophilic free radicals bonded to the ends of the three-dimensional graphene foam absorb water droplets within 0.1 to 0.2 seconds. Unlike other methyl-containing solvents, acetone forms highly reactive methyl radicals during pyrolysis. Ethanol tends to dehydrate rather than form methyl radicals, but acetone typically pyrolyzes to produce methyl radicals and carbon monoxide.

[0189] Experimental Example 3: Physical Property Analysis The structure and elemental properties of three-dimensional graphene were measured using a field emission scanning electron microscope (FE-SEM, Hitachi S-4800, Japan) equipped with an X-ray energy dispersive spectroscopy (EMAXENERGY EX-250, Horiba, Japan) at an accelerating voltage of 20 kV. Furthermore, to investigate the morphological structure of three-dimensional graphene, images were obtained using a scanning transmission electron microscope (STEM, JEOL JEM-2100F, Japan) equipped with an aberration (Cs) corrector at an accelerating voltage of 200 kV. See [link to relevant documentation]. Figure 5 To prepare the sample, powdered three-dimensional graphene was sonicated in anhydrous ethanol, and then 6 μL of the solution was dropped onto a carbon-coated copper mesh (TEM). For FT-IR spectroscopy, at a resolution of 1 cm⁻¹... -1 The data were obtained using an infrared spectrometer (Spectrum 2, PerkinElmer) in attenuated total reflectance (ATR) mode with 64 scans, which can be found in [reference needed]. Figure 6 .

[0190] Figure 5 These are scanning electron microscope (SEM) images of three-dimensional graphene foams whose wettability was adjusted under microwave irradiation in different solvents. All three-dimensional graphene foams exhibited a three-dimensional graphene network with large pores (×1000, ×5000) and wrinkled graphene surfaces (×50000 and ×100000). Despite repeated adjustments to wettability, the structural properties of the three-dimensional graphene foams were well maintained, demonstrating structural stability.

[0191] Figure 6 a is the hydroxylation in Examples 1-2 and 1-3 (left side, 3000 to 3600 cm). -1 (absorption band) and methylation (right side, 2960 cm⁻¹) -1 Fourier transform infrared spectroscopy (FTIR) measurement results of three-dimensional graphene foam (peaks). Figure 6 The results on the left side of a indicate that when comparing synthesized three-dimensional graphene with three-dimensional graphene irradiated with microwaves under water-mediated conditions, the results show that at 3000 to 3600 cm⁻¹… -1 A broad absorption band appears in the region, which was not observed in acetone-based microwave irradiation; therefore, water is responsible for the chemisorption of polar functional groups. On the other hand, Figure 6 The results on the right side of b indicate that when comparing three-dimensional graphene with acetone-mediated microwave irradiation of three-dimensional graphene, at 2960 cm⁻¹... -1 An additional peak appeared at (right side), which was not observed in the three-dimensional graphene irradiated with microwaves under water-mediated conditions, indicating that nonpolar groups were chemically adsorbed at the ends of the graphene.

[0192] Figure 6 b is about synthesis (left side, 3000 to 3700 cm) -1 Three-dimensional graphene based on water treated with microwaves (intermediately, 3000 to 3700 cm⁻¹) -1 ) and acetone-based microwave treatment (right side, 2800 to 3500 cm⁻¹) -1 Fourier transform infrared (FT-IR) peak decomposition results of three-dimensional graphene. The stretching vibration bands of decomposed hydroxyl and methyl groups are shown in gray. It can be confirmed that the wettability of three-dimensional graphene changes due to the chemisorption of hydroxyl or methyl radicals. (The text then abruptly shifts to a description of peak decomposition in the 2900–3700 cm⁻¹ region.) -1 When decomposing the spectra of the three-dimensional graphene synthesized in Examples 1-1 within the specified range, the results were obtained at 3322, 3180, and 3057 cm⁻¹, respectively. -1 Three smaller N–H, NH2 and =C–H stretching vibration peaks appeared at the point, which may be caused by the pyrolysis of the melamine skeleton during the synthesis of three-dimensional graphene.

[0193] In the spectrum of three-dimensional graphene irradiated by microwaves under water-mediated conditions, at 3320 cm⁻¹... -1 The presence of additional O–H stretching vibration bands indicates that hydroxyl radicals are chemisorbed onto the surface of the three-dimensional graphene.

[0194] Experiment Example 4: Density Functional Theory (DFT) Calculation Density functional theory (DFT) calculations were performed using the Gaussian 09 (G09) package. The input configurations of graphene (10 rings), hydroxyl radicals, and methyl radicals were based on the 6+31G** basis set and optimized using DFT / B3LYP.

[0195] Energy maps of the chemisorption of methyl and hydroxyl groups onto the graphene edge were obtained by adjusting the bonding distance between the immobilized radicals and the graphene edge using a repeat option, while energy maps of the desorption process were calculated using the QST2 and QST3 methods. All calculations were visualized using the Chemcraft 1.8 package, which can be found here. Figure 7 .

[0196] Here, 6+31G** is a basis set used to solve for the density function. The 6 and 31 represent the inner shell electron orbitals, which are represented by six Gaussian functions, while the outermost electron orbitals are represented by two orbitals, each containing three and one Gaussian function, respectively. The + signifies diffusion functions, which represent changes in orbitals caused by ionization, intermolecular interactions (such as dispersion forces and hydrogen bonding), etc. The ** signifies the introduction of d and p orbitals to account for the polarization of orbitals caused by chemical bond formation. DFT / B3LYP is a functional used for structure optimization; it is a hybrid model based on the Becke potential, supplemented with three parameters: Lee, Yang, and Parr.

[0197] Figure 7 a is an energy diagram of the hydroxyl groups at the ends of the three-dimensional graphene with hydrophilic free radicals in Examples 1-2. When a methyl free radical approaches the three-dimensional graphene with hydroxyl free radicals at the ends, the activation energy of the substitution reaction decreases to 1.82 eV as a methanol-like intermediate is formed.

[0198] Figure 7 b is an energy diagram of the methylation at the ends of three-dimensional graphene with hydrophobic free radicals in Examples 1–3. When a hydroxyl radical approaches the three-dimensional graphene with a methyl radical at its end, the activation energy of the substitution reaction decreases to 1.99 eV as a methanol-like intermediate is formed. When the pre-adsorbed functional group desorbs from the three-dimensional graphene, the methyl or hydroxyl radical undergoes spontaneous chemisorption, thereby allowing for immediate and reversible regulation of wettability.

[0199] Experiment Example 5: Electrochemical Performance Evaluation of Electrochemical Double-Layer Capacitors To evaluate the electrochemical performance of the electrochemical double-layer capacitors (EDLCs) of Examples 1 to 4 based on 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM-TFSI), two identical electrodes were assembled into a Type 2032 coin cell using 100 μL of electrolyte in a glove box filled with high-purity argon (oxygen and water less than 0.01 ppm, VTI, USA). Electrochemical performance was measured using a multichannel potentiostat / galvanostat (WMPG 1000, WonATech). Electrochemical impedance spectroscopy (EIS) was performed using a potentiostat / galvanostat (Bio-Logic, VMP3, France). For the aqueous electrolyte-based electrochemical double-layer capacitor (EDLC), the electrodes were prepared as a three-electrode system, with a silver / silver chloride reference electrode and a platinum counter electrode immersed together in 50 mL of a 6 mol / L potassium hydroxide aqueous electrolyte. Electrochemical performance and electrochemical impedance spectroscopy were measured using a multichannel potentiostat / galvanostat (ZIVE MP1, WonATech), which can be found in [reference needed]. Figure 8 .

[0200] In all calculations concerning electrochemical performance, the capacitance for the galvanostatic charge-discharge (GCD) method is based on the following mathematical formula 1, which can be found in [reference 1]. Figure 9 and Figure 10 .

[0201] [Mathematical Expression 1] Cs = (I·Δtd) / (m·(Vmax-Vmin)) Where Cs is the electrostatic capacitance (F·g) -1 I is the current, Δtd is the discharge time (s), m is the mass of the active material of the electrode (g), and (Vmax - Vmin) is the potential change.

[0202] Figure 8 a is the cyclic voltammetry (CV) curve of a three-dimensional graphene-based electrode with hydrophobic free radicals bonded at its ends in contact with a nonpolar (EMIM-TFSI) or polar (6M KOH) solvent. Figure 8 b is the cyclic voltammetry (CV) curve when a three-dimensional graphene-based electrode with hydrophilic free radicals at its ends is contacted with a nonpolar or polar solvent. For electrochemical double-layer capacitors (EDLCs) in which a polarity-mismatched electrode is immersed in a nonpolar (EMIM-TFSI) electrolyte, even with the scan rate increased to 1000 mV / s... -1 The current density showed almost no increase compared to the other three electrodes, and the polarity mismatch significantly reduced the performance of the electrochemical double-layer capacitor (EDLC) based on the nonpolar (EMIM-TFSI) electrolyte.

[0203] Figure 9 a represents the galvanostatic charge-discharge (GCD) curves of superhydrophobic three-dimensional graphene foam-based electrodes in contact with nonpolar (EMIM-TFSI) and polar (6M KOH) electrolytes at different current densities. Figure 9 b represents the galvanostatic charge-discharge (GCD) curves of the superhydrophilic three-dimensional graphene-based electrode in contact with nonpolar (EMIM-TFSI) and polar (6M KOH) electrolytes at different current densities. The GCD was calculated according to Equation 1. For the use of a polarity-mismatched nonpolar (EMIM-TFSI) electrolyte... Figure 9 The electrochemical double-layer capacitor of b, with polarity matching Figure 9 Compared to the previous method, due to the larger ohmic drop and shorter discharge time, it deviates significantly from the typical triangular constant current charge-discharge (GCD) curve.

[0204] Figure 9 c is based on Figure 9 The capacitance was calculated using the galvanostatic charge-discharge (GCD) method. Electrochemical double-layer capacitors using polarity-matched nonpolar electrolytes (EMIM-TFSI) and polarity-matched polar electrolytes (6 M KOH) exhibited significantly higher capacitances compared to those with polarity mismatch (4.96 times and 2.16 times, respectively, at a current density of 0.1 A / g), and also showed less capacitance decay at higher current densities (above 0.5 A / g).

[0205] Figure 10 a is the galvanostatic charge-discharge (GCD) curve of an electrochemical double-layer capacitor (EDLC) manufactured using a nonpolar (EMIM-TFSI) electrolyte after 5 cycles at 0.2 A / g. Figure 10 b shows the galvanostatic charge-discharge (GCD) curves of an electrochemical double-layer capacitor (EDLC) manufactured using a nonpolar (EMIM-TFSI) electrolyte for 5 cycles at 1 A / g. At 0.2 A / g, compared to a polarity-matched EDLC, the polarity-mismatched EDLC exhibits severe capacitance decay, significant ohmic drop, and a shorter discharge time after the first cycle. As the current density increases to 1 A / g, the performance degradation further intensifies, with 5 charge-discharge cycles completed within 3 seconds, and a voltage deviation of 0 to 0.27 V appearing after one cycle.

[0206] Figure 10c indicates that polarity matching has a more favorable effect on the cycle life of electrochemical double-layer capacitors (EDLCs) than polarity mismatch. With polarity matching, the capacitance retention rate is 110.1% after 10,000 cycles at 1 A / g, showing excellent cycle life. However, with polarity mismatch, severe lifetime degradation occurs, and only 33.3% of the capacitance is retained.

[0207] Experimental Example 6: Amino Content Analysis To analyze the amino content within the carbon nanotubes manufactured in one embodiment and comparative example of the present invention, thermogravimetric analysis (TGA, HITACHI, STA7300) was performed. Approximately 4.5 mg of carbon nanotubes were placed on a platinum dish, equilibrated at 30°C for 10 minutes, and then heated to 800°C at a rate of 10°C / min under a nitrogen atmosphere. The ash content was evaluated at approximately 600°C, and the results are shown below. Figure 13 middle.

[0208] Reference Figure 13 It can be confirmed that the TGA analysis results of the carbon nanotubes of Comparative Example 1-1, Comparative Example 3-1 and Example 2-1 show that the amino ratio of the amino-modified carbon nanotube of Example 2-1 is 1.9% by weight, which may mean that there is one amino functional group bonded on every 17 carbon rings.

[0209] Experimental Example 7: Evaluation of Carbon Nanotube Modification To confirm the carbon nanotube modification according to one embodiment and comparative example of the present invention, measurements were performed using Fourier transform infrared spectroscopy (FT-IR). For FT-IR spectroscopy, a resolution of 1 cm⁻¹ was used. -1 The modified carbon allotropes were measured using an infrared spectrometer (Spectrum 2, PerkinElmer) in attenuated total reflectance (ATR) mode with 64 scans, and the results are shown in... Figure 14 middle.

[0210] Reference Figure 14 The curve on the left shows that no N–H stretching vibration peak (3400 cm⁻¹) was observed in the carbon nanotubes of Comparative Example 1-1. -1 ), while in Example 2-1 Figure 14 The N–H stretching vibration peak (3400 cm⁻¹) was observed in the curve on the left side. -1 ) and in Figure 14 A C–N stretching vibration peak (1120 cm⁻¹) was observed in the curve on the right side. -1 This may mean that chemical bonds are formed between carbon nanotubes and amino groups through microwave-induced free radical reactions, thereby achieving effective modification of carbon nanotubes by amino groups.

[0211] Experiment Example 8: Dispersion Assessment The dispersibility was evaluated by measuring the dynamic light scattering (DLS) of carbon nanotubes according to one embodiment and comparative example of the present invention. Carbon nanotubes from Example 2-1, Comparative Example 1-1, and Comparative Example 3-1 were ultrasonically dispersed in N-methylpyrrolidone (NMP) at a concentration of 0.025% by mass for 24 hours, diluted to 0.00025% by mass, and then their dynamic light scattering (DLS) was measured. Subsequently, in order to forcibly separate the carbon nanotubes from N-methylpyrrolidone (NMP) of Example 2-1, Comparative Example 1-1, and Comparative Example 3-1, centrifugation was performed at 1000 to 1200 rpm, and the results are shown below. Figures 15 to 17 middle.

[0212] Reference Figure 15 ,from Figure 15 The amino-modified carbon nanotubes of Example 2-1 were confirmed to have only two peaks around 5 nm and 100 nm, indicating that the amino-modified carbon nanotubes of Example 2-1 were completely dispersed in a polar solvent. On the other hand, from... Figure 15 It can be confirmed that the carbon nanotubes of Comparative Example 1-1 have two peaks near approximately 10 nm and approximately 320 nm, while the carboxyl-modified carbon nanotubes of Comparative Example 3-1 have two peaks near approximately 30 nm and approximately 260 nm. This may mean that van der Waals forces and π-π stacking phenomena exist between hydrophobic carbon nanotubes, leading to aggregation in polar solvents.

[0213] Reference Figure 16 In Example 2-1, the amino groups of the amino-modified carbon nanotubes act as electron-donating groups (EDG), while the carbonyl groups in the N-methylpyrrolidone (NMP) solvent act as electron-withdrawing groups (EWG). This may mean that the dispersibility of the solvent is improved due to the interaction between the two. On the other hand, in Comparative Example 3-1, the carboxyl groups of the carboxyl-modified carbon nanotubes act as electron-withdrawing groups (EWG). This may mean that the carboxyl groups interact with the electron-withdrawing groups (EWG) of the carbonyl groups in the N-methylpyrrolidone (NMP) solvent, resulting in reduced dispersibility.

[0214] Reference Figure 17It was confirmed that the amino-modified carbon nanotubes of Example 2-1 exhibited excellent dispersibility in N-methylpyrrolidone (NMP) solvent, even after centrifugation at 1000 rpm and 1200 rpm. On the other hand, the carbon nanotubes of Comparative Example 1-1 showed sedimentation after centrifugation at 1000 rpm and 1200 rpm for 2 minutes. The carboxyl-modified carbon nanotubes of Comparative Example 3-1 also showed sedimentation after centrifugation at 1200 rpm. This may indicate that the carbon nanotubes of Comparative Examples 1-1 and 3-1 exhibited poor dispersibility in polar solvents.

[0215] Experiment Example 9: Evaluation of Electrochemical Characteristics of Coin Cells The electrochemical properties of coin cells according to an embodiment and comparative examples of the present invention were evaluated. Electrochemical performance was tested using a multichannel potentiostat / galvanostat (WMPG 1000, WonATech). Galvanostat charge-discharge tests of the coin cells were conducted at different rates (charge-discharge rate, 1C = 170 mAh / g) of 2.5–4.0 V vs. Li / Li+. Electrochemical impedance spectroscopy (EIS) was measured using a potentiostat / galvanostat (Bio-Logic, VMP3, France), and the results are shown below. Figures 18 to 22 middle.

[0216] Figure 18 The capacity changes of the coin cells of Examples 2-3, Comparative Examples 1-3, 3-3 and 4-3 after 150 charge-discharge cycles are shown. It can be confirmed that the coin cells of Examples 2-3 with uniformly distributed amino-modified carbon nanotubes exhibit the best capacity in long-term cycling.

[0217] Figure 19 The capacity changes of the coin cells in Examples 2-3, Comparative Examples 1-3, 3-3, and 4-3 at different rates are shown. (Refer to...) Figure 19 Compared to the coin cells of Comparative Examples 4-3 and 1-3, the coin cells of Examples 2-3 showed an increase in capacity of approximately 10 mAh / g at 3C and an increase of approximately 20 mAh / g at 5C. Furthermore, at an ultra-high rate of 10C, the capacity was increased by approximately 100 mAh / g compared to the coin cells of Comparative Examples 4-3 and by approximately 30 mAh / g compared to Comparative Examples 1-3. These results indicate that the electrode slurry containing amino-modified carbon nanotubes exhibits excellent dispersibility, and since the amino-modified carbon nanotubes of Example 2-1 are uniformly distributed in the coin cells, optimal capacity is confirmed to be exhibited during high-rate charge and discharge.

[0218] Reference Figure 20Electrochemical impedance spectroscopy (EIS) measurements of the coin cells in Examples 2-3, Comparative Examples 1-3, and 3-3 showed that the coin cells in Comparative Examples 1-3 and 3-3 had a higher Ro value of over 110 Ω. CT (charge transfer resistance), while the coin cells using amino-modified carbon nanotubes in Examples 2-3 have a lower Ri of approximately 67 Ω. CT This may mean that when carbon nanotubes are well dispersed, they promote charge transfer at the electrode-electrolyte interface, thus improving the battery's capacity characterization and rate performance.

[0219] Figure 21 This shows the capacity change of the coin cells of Examples 2-3, Comparative Examples 1-3, 2-3, and 3-3 after 200 charge-discharge cycles. (Refer to...) Figure 21 It can be confirmed that the coin cells of Comparative Examples 2-3 containing single-walled carbon nanotubes exhibit a sharp decrease in capacity after more than 100 charge-discharge cycles. On the other hand, it can be confirmed that the coin cells of Examples 2-3 containing amino-modified multi-walled carbon nanotubes retain 88.7% of their capacity after 200 charge-discharge cycles, demonstrating superior cycle life compared to Comparative Examples 2-3 containing single-walled carbon nanotubes.

[0220] Figure 22 The capacity variations of the coin cells of Examples 2-3, Comparative Examples 1-3, 2-3, and Comparative Example 3-3 at different ratios are shown. (Refer to...) Figure 22 It can be confirmed that the coin cells of Comparative Examples 2-3 containing single-walled carbon nanotubes exhibit the highest capacity under low-speed charge-discharge (0.1 to 3.0C), but their capacity is lower than that of the coin cells of Examples 2-3 under high-speed charge-discharge (0.1 to 3.0C). Furthermore, in terms of ultra-high rate performance, compared to Comparative Examples 2-3, the coin cells of Examples 2-3 have a capacity approximately 25 mAh / g higher at 5C and approximately 100 mAh / g higher at 10C. This confirms that amino-modified carbon nanotubes exhibit excellent dispersibility for N-methylpyrrolidone (NMP) even without a dispersant, thus enabling the coin cells of Examples 2-3 to have superior rate performance compared to the coin cells of Comparative Examples 2-3 containing single-walled carbon nanotubes.

[0221] While preferred embodiments of the present invention have been described above, the present invention is not limited thereto. Various modifications can be made within the scope of the claims, specification, and drawings, and these modifications also fall within the scope of the present invention.

[0222] Therefore, the substantive scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for modifying the wettability of carbon allotropes, comprising: Steps for preparing carbon allotropes; The steps of preparing a solvent that can induce the generation of hydrophilic or hydrophobic free radicals; The step of contacting the carbon allotrope with the solvent; the step of supplying energy to the solvent using an energy supply source; as well as The step of generating hydrophilic or hydrophobic free radicals of the solvent by supplying energy to the solvent, and having the generated free radicals bond to the ends of carbon allotropes.

2. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, The carbon allotrope is composed of sp2 hybridized carbon atoms.

3. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, The steps for preparing carbon allotropes include: coating carbon allotropes onto porous foam; and drying the carbon allotropes coated onto the porous foam.

4. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, The energy source is selected from at least one of microwaves, electric fields, and plasma.

5. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, The solvents capable of inducing the generation of hydrophilic free radicals include solvents capable of generating polar free radicals.

6. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, The solvents capable of inducing the generation of hydrophobic free radicals include solvents capable of generating nonpolar free radicals.

7. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, The solvent that can induce the generation of hydrophilic free radicals is a solvent containing hydroxyl groups. The solvent that can induce the generation of hydrophobic free radicals is a solvent containing methyl or benzyl groups.

8. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, The solvent capable of inducing the generation of hydrophilic free radicals is water, hydrogen peroxide, or a combination thereof. The solvent capable of inducing the generation of hydrophobic free radicals is acetone, toluene, or a combination thereof.

9. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, When the solvent is a solvent capable of inducing the generation of hydrophilic free radicals, the energy supply time for the step of supplying energy to the solvent using an energy supply source is less than a few minutes.

10. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, The step of bonding the generated free radical to the end of the carbon allotrope is carried out under at least one inert gas selected from the group consisting of argon, helium, xenon, krypton and neon.

11. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, When the solvent is a solvent capable of inducing the generation of hydrophobic free radicals, the energy supply time for the step of supplying energy to the solvent using an energy supply source is less than a few minutes.

12. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, For the step of supplying energy to the solvent using an energy supply source, the water contact angle (WCA) can be adjusted according to the energy supply time.

13. The method for modifying the wettability of carbon allotropes according to claim 3, wherein, The porous foam includes at least one porous foam selected from the group consisting of melamine foam, polyurethane foam, nickel foam, loofah sponge, and natural foam.

14. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, The carbon allotrope is selected from one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanofibers, graphene oxide, and two-dimensional graphene.

15. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, When the hydrophobic free radical bonds to the end of the carbon allotrope, the water contact angle (WCA) is greater than 110°.

16. The method for modifying the wettability of carbon allotropes according to claim 1, wherein, When the hydrophilic free radical bonds to the end of the carbon allotrope, the water contact angle (WCA) is less than 50°.

17. A method for modifying the wettability of carbon allotropes, comprising: Steps for preparing carbon allotropes; The steps for preparing a solvent that can induce the generation of hydrophilic free radicals; The step of contacting the carbon allotrope with the solvent; The step of supplying energy to the solvent using an energy supply source; The step of generating hydrophilic free radicals within the solvent by means of energy supplied to the solvent; as well as The step of obtaining a carbon allotrope modified with a hydrophilic group by bonding the hydrophilic free radical to the end of the carbon allotrope.

18. The method for modifying the wettability of carbon allotropes according to claim 17, wherein, The steps of generating hydrophilic free radicals within the solvent by using energy supplied to the solvent include: The steps of generating an amino radical in the solvent by means of energy supplied to the solvent; and the steps of bonding the amino radical to the end of the carbon allotrope to obtain an amino-modified carbon allotrope.

19. The method for modifying the wettability of carbon allotropes according to claim 18, wherein, The modified carbon allotropes contain 1 to 7 wt% amino groups based on total carbon allotropes.

20. The method for modifying the wettability of carbon allotropes according to claim 17, wherein, The energy supply time for the energy supply step is less than a few minutes.

21. The method for modifying the wettability of carbon allotropes according to claim 18, wherein, The solvents capable of inducing the generation of amino radicals include: The first solvent having hydroxyl groups; and A second solvent containing an amino group.

22. The method for modifying the wettability of carbon allotropes according to claim 21, wherein, The first solvent is hydrogen peroxide or water. The second solvent is urea or melamine.

23. The method for modifying the wettability of carbon allotropes according to claim 18, wherein, The solvents that can induce the generation of amino free radicals are hydrogen peroxide and urea.

24. The method for modifying the wettability of carbon allotropes according to claim 23, wherein, The hydrogen peroxide and urea are mixed in a ratio of 1:1 to 1:

4.

25. The method for modifying the wettability of carbon allotropes according to claim 17, wherein, The carbon allotropes include single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanofibers, graphene, or graphene oxide.

26. A method for modifying the wettability of carbon allotropes, comprising: The step of contacting a hydrophilic carbon allotrope with a hydrophilic substituent located at the end of the carbon allotrope and then contacting a solvent capable of inducing the generation of hydrophobic free radicals. The step of supplying energy to the solvent using an energy supply source; as well as The step of converting a hydrophilic carbon allotrope into a hydrophobic carbon allotrope by means of energy supplied to the solvent.

27. The method for modifying the wettability of carbon allotropes according to claim 25, wherein, The energy supply time for the step of converting a hydrophilic carbon allotrope into a hydrophobic carbon allotrope is less than a few minutes.

28. The method for modifying the wettability of carbon allotropes according to claim 25, wherein, The energy source is selected from at least one of microwaves, electric fields, and plasma.

29. A method for modifying the wettability of carbon allotropes, comprising: The step of contacting a hydrophobic carbon allotrope with a hydrophobic substituent located at the end of the carbon allotrope and then contacting a solvent capable of inducing the generation of hydrophilic free radicals. The step of supplying energy to the solvent using an energy supply source; as well as The step of converting a hydrophobic carbon allotrope into a hydrophilic carbon allotrope by means of energy supplied to the solvent.

30. The method for modifying the wettability of carbon allotropes according to claim 29, wherein, The energy supply time for the step of converting a hydrophobic carbon allotrope into a hydrophilic carbon allotrope is less than a few minutes.

31. The method for modifying the wettability of carbon allotropes according to claim 29, wherein, The energy source is selected from at least one of microwaves, electric fields, and plasma.

32. A wettability-modified carbon allotrope, wherein, Hydrophobic substituents are located at the ends of carbon allotropes and thus exhibit hydrophobicity.

33. The wettability-modified carbon allotrope according to claim 32, wherein, The water contact angle (WCA) of the carbon allotrope is greater than 110°.

34. A wettability-modified carbon allotrope, wherein, Hydrophilic substituents are located at the ends of carbon allotropes and thus exhibit hydrophilicity.

35. The wettability-modified carbon allotrope according to claim 34, wherein, The water contact angle (WCA) of the carbon allotrope is less than 50°.

36. A wettability-modified carbon allotrope, wherein, The carbon allotrope has an amino group bonded to its end.

37. The wettability-modified carbon allotrope according to claim 36, wherein, The modified carbon allotrope includes an absorption region in the FT-IR spectrum at 1120 cm -1 and 3400 cm -1 bands.

38. The wettability-modified carbon allotrope according to claim 36, wherein, The modified carbon allotropes have a size of 50 to 200 nm.

39. The wettability-modified carbon allotrope according to claim 36, wherein, The modified carbon allotrope has a water contact angle (WCA) of less than 50°.

40. The wettability-modified carbon allotrope according to claim 36, wherein, The carbon allotrope is composed of sp2 hybridized carbon atoms.

41. The wettability-modified carbon allotrope according to claim 36, wherein, The carbon allotrope is selected from one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanofibers, graphene oxide, and two-dimensional graphene.

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