KR101996811B1 - Method of fabricating high-quality graphene flakes using electrochemical exfoliation process and dispersion solution of graphene flakes - Google Patents

Abstract

A method for producing graphene flakes includes the steps of impregnating an anode and a cathode containing a graphene precursor into an electrolyte solution containing a metal salt of an anionic organic monomolecule, applying a voltage to the anode and the cathode, Separating the graphene flakes from the graphene precursor by forming an intercalation compound of monomolecules and the graphene precursor, and separating the graphene flakes from the precursor solution comprising the graphene flakes.

Description

METHOD OF FABRICATING HIGH-QUALITY GRAPHENE FLAKES USING ELECTROCHEMICAL EXPLOITATION PROCESS AND DISPERSION SOLUTION OF GRAPHENE FLAKES BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a method for producing graphene flakes. More particularly, the present invention relates to a process for preparing graphene flakes using electrochemical stripping and to a dispersion solution of graphene flakes.

Graphene is a two - dimensional planar structure carbon isotope with sp2 hybrid structures, in which carbon atoms are bonded in a honeycomb or network. Graphene, for example, has about two times the thermal conductivity of diamond and about 1,000 times the electrical conductivity of copper, and has excellent mechanical properties such as tensile strength close to that of steel. Therefore, graphene is being applied / studied in various engineering fields such as nanoscale electric and electronic devices, nanosensors, optoelectronic devices, electrode additives, and high performance composite materials.

Graphene is present graphitized by individual unitary van der Waals forces and may require a stripping process from graphite to graphene for industrial applications.

Conventionally, representative methods developed for producing graphene include a top-down method of peeling a graphene flake having a single layer or a water layer from a graphene precursor such as graphite, and a method using a carbon source such as methane gas, organic monomers and polymers There is a bottom-up method in which graphene is synthesized on a specific substrate or a graphene film is produced using a heat treatment of a substrate containing a carbon component.

For example, top-down methods include mechanical stripping such as scotch tape stripping or ball-milling, liquid phase stripping using an ultrasonic process or solvent shear after mixing graphite in an organic solution, There is an oxidation-reduction method in which graphene is produced by removing the graphene oxide produced by peeling and then using a reduction reaction.

For example, the bottom-up method is chemical vapor deposition (CVD) or silicon carbide (SiC) heat treatment.

In the case of the top-down method using a scotch tape or a bottom-up method, high-quality graphene free from structural defects can be produced, but the manufacturing yield is low or the manufacturing cost is high, which is disadvantageous for mass production.

On the other hand, in the case of the liquid phase stripping method and the oxidation-reduction method, there is an advantage that the mass process is relatively easy and the raw material is cheap. However, in the case of graphene produced by the above method, the size of the produced graphene is limited to a few hundred nanometers or less, and the defect rate and oxidation degree of the produced graphene are increased, thereby realizing excellent characteristics expected from the ideal graphene It is difficult to do.

Recently, some methods for producing graphene flakes from graphite using an electrochemical process have been reported. When an electrochemical process is used, graphene flakes having a size of several micrometers or more through a single process can be produced from graphite with high yield.

Non-Patent Document 1 reports on a graphene peeling method through an electrochemical process that has been reported previously.

Patent Document 1 reports a method of electrochemically peeling off graphene using a sulfuric acid electrolyte. However, when a sulfuric acid electrolyte is used, the chemical reaction between the radicals generated by the decomposition of sulfuric acid molecules in the electrolyte and the graphite proceeds, and the defect rate of graphene flakes finally produced is increased.

Patent Document 2 reports interlaminar intercalation of alkali metal into graphite interlayer using an electrochemical method, followed by graphene peeling through an additional process. However, in the case of the intercalation reaction by the metal ion, since the relatively small size of the inserted metal ion does not cause peeling or its efficiency is not high, an additional peeling process is indispensably required.

Patent Document 3 reports a method of electrochemically inserting ammonium monomolecules to peel off graphene and graphite flakes. However, in the case of the produced graphene, more than 90% of the graphene layer has a thickness of 10 layers or more, which is close to a graphite flake thinner than graphene in a conventional sense.

As described above, graphene flake production methods using conventional electrochemical methods have disadvantages that the produced graphene flakes have a high defect rate, require additional processing, are limited in size, or have a large thickness.

Therefore, for effective industrial application of graphene, it is required to develop a process in which the size of graphene is made as large as possible, and the thickness is made as thin as possible while ensuring a low defect rate.

1. US registered patent US 8,858,776 2. International Patent Publication PCT / SG2011 / 000225 3. International patent application PCT / GB2012 / 000233

1. Pei Yu, Sean E. Lowe, George P. Simon, and Yu Lin Zhong, "Electrochemical exfoliation of graphite and the production of functional graphene ", Current Opinion in Colloid and Interface Science, Volume 20, Issues 56, October, 329-338

An object of the present invention is to provide a method for producing graphene flakes that is economical, mass-producible, and capable of producing high-quality graphene flakes.

Another object of the present invention is to provide a dispersion solution of graphene flakes with improved dispersibility.

According to another aspect of the present invention, there is provided a method of manufacturing a graphene flake, comprising: preparing a positive electrode and a negative electrode including a graphene precursor by using an anionic organic monomolecular metal salt, Impregnating the electrolyte solution with a solvent, applying a voltage to the positive electrode and the negative electrode to form an intercalation compound of the anionic organic monomolecule and the graphene precursor, thereby peeling the graphene flake from the graphene precursor, Separating the graphene flake from a precursor solution comprising graphene flakes.

According to one embodiment, the graphene precursor comprises at least one selected from the group consisting of natural graphite, artificial graphite and carbon fiber.

According to one embodiment, the anionic organic monomers include at least one anionic functional group and a chain structure or benzene derivative structure associated therewith.

According to one embodiment, the anionic functional group is selected from the group consisting of a sulfate (SO ₂ ^- ) sulfonate (SO ₃ ^- ), a nitrite (NO ₂ ^- ), a nitrate (NO ₃ ^- ), A phosphite (PO ₃ ^3- ), a phosphate group (PO ₄ ^3- ), a carboxylate group (COO ^- ) and a carbonate group (CO ₃ ^2- ) At least one selected from the group.

According to one embodiment, the anionic organic monomolecule comprises at least one anionic functional group and a chain structure associated therewith, and includes formic acid, acetic acid, 1,2-ethanediamine (1, 2-ethanediamine, ethanesulfonate, ethyl ethanesulfonate, 2- (methylamino) ethane sulfonate, 2- (2-bromoethanesulfonate) 2-Hydroxy-3- (Phosphonooxy) propionic acid, 2-Hydroxy-3- (Phosphonooxy) propionate, Propanoic acid), glycerate 3-phosphate, 2- (4-isobutylphenyl) propanoic acid phosphate, 3- (3,5-dihydroxyphenyl) Phenyl) -1-propionic acid sulfate (3- (3,5-Dihydroxyphenyl) -1-Propanoic Acid Sulphate), (3- Propanoic acid, propanenitrile, propane nitrite, 3-hydroxypropane-1-sulfonic acid, succinic acid, succinic acid, Butyrate, butane phosphate, butane phosphate, 1,2,4-tricarboxylic acid (Pbtc), butanoic acid, butane sulphate, butane sulphate, butane sulphate, butane sulphate, butane sulphate, butane sulphate, Succinyl Chloride, Daminozide, Succinic Acid Bis (3,4,5-trimethoxybenzylidenehydrazide)), succinic acid, 2-Amino-Succinic Acid 4-Ethyl Ester, 2,2,3,3-Tetrafluoro-Succinic Acid, Methylene succinic acid 4-methyl ester, pentanoic acid, pentanyl phosphate, bis [4- (2,4,4-trimethyl-2- Penta 2-Pentanyl) Phenyl] Hydrogen Phosphate, Hexanoic Acid, 3-Hexenyl Pentanoate, and the like. Hexane Carboxylic Acid, 1-Hexanesulfonic Acid, Hexylphosphonic Acid, Butyl 4-Nitrophenyl Hexylphosphonate, Hexyl Phosphonic Dichloride, Hexylphosphonic acid, hexylphosphonic dichloride, methyl 4-methylumbelliferyl hexylphosphonate, heptylcarboxylic acid, 1-heptanesulfonic acid, 4-heptylbenzoic acid Propylphosphonic acid, bicyclo [2.2.1] heptane-1-carboxylic acid, heptane-2-carboxylic acid, Heptyl acetate, octane carboxy acid, bicyclo [2.2.1] heptyl < RTI ID = 0.0 & Octyl-1-carboxylic acid (Bicyclo [2.2.2] Octane-1-Carboxylic Acid), 4-pentylbicyclo [2.2.2] octane- Octylphosphonic acid, octylsulfonic acid, 1-octane sulfonic acid, 4-octylbenzenesulfonic acid, 1-octanesulfonate, (1-octanesulfonate), octylphosphonic acid, 1- (octane-1-sulfinyl) -Octane, octane-2-sulfonate Dodecyl Sulfate, Dodecyl Carboxylic Acid, Dodecyl Nitrate, Dodecyl 2-Bromothiophene-4-carboxylate 4-Dodecylbenzenesulfonic Acid, Dodecyl Sulfonic, Dodecyl Sulfonic Acid, Dodecylbenzenesulfonate, N-dodecylsulfonic Acid, Phosphonic acid (ND odecylphosphonic acid) and 1-dodecylphosphonic acid.

According to one embodiment, the anionic organic monomolecule comprises at least one anionic functional group and a chain structure associated therewith and is selected from the group consisting of benzoic acid, 4-aminobenzoic acid, Benzenesulfonic Acid, Benzene Sulfonamide, Alkylbenzene Sulfonate, Phenyl Phosphate, Dodecylbenzenesulphonic Acid, 2-formyl-benzene-1,4-disulfide, Naphthalene sulfonic acid, Naphthalene Carboxylic Acid, Naphthoquine Phosphate, Naphthalene Acetic Acid, Naphthalene Sulfuric Acid, Naphthalene Phosphoric Acid, 1-Naphthoic Acid, 4-Amino-1-Naphthalenesulfonic Acid, 6- (P-Tolyldino) -2 (P-Toluidino) -2-Naphthalenesulfonic Acid) 4-hydroxy-1-naphthalenesulfonic acid, 4-amino-1-naphthalenesulfonate, 1,4,5,8-naphthalenesulfonic acid, Naphthalenetetracarboxylic dianhydride, 4,8-dimethoxy-naphthalene-1-carbaldehyde, 4-benzyloxy- Naphthalene-1-sulfonyl chloride, 4-benzyloxy-naphthalene-1-sulfonyl chloride, 4-Chloro-Naphthalene-1-sulfonyl chloride, 5-amino-naphthalene-1-sulfonyl chloride, 5-bromo-naphthalene-1-sulfonyl chloride, 5-formylamino- 1-sulfonyl chloride, 5-methylamino-naphthalene-1-sulfonyl chloride, (1-naphthalene) Trifluoro 1-Naphthalene Trifluoroborate, 7-hydroxy-1,2,3,4-tetrahydro-naphthalene-2-carboxylic acid Acid), 7-Bromo-3-Hydroxy-Naphthalene-2-Carboxylic Acid, 4-oxo-1,2,3,4-tetrahydro- 2-carboxylic acid (4-Oxo-1,2,3,4-Tetrahydro-Naphthalene-2-Carboxylic Acid), 5 - [(2- ethylpiperidine- Sulfonyl chloride (5 - [(2-Ethyl-Piperidine-1-Carbonyl) -amino] -Naphthalene- 1 -sulfonyl Chloride), 5- (2,2,2-trifluoro- Naphthalene-1-sulfonyl chloride (5- (2,2,2-Trifluoro-Acetylamino) -Naphthalene-1-sulfonyl Chloride) (Acetyl-Ethyl-Amino) -Naphthalene-1-sulfonyl Chloride, 3- (Naphthalene-2-sulfonyl) -Propionic Acid, 2- (propylsulfonyl) naphthalene( Anthracene 1-Sulfonic Acid, Anthracene 1-Sulfonic Acid, Anthracene 1-Sulfonic Acid, 2- (Propylsulfonyl) Naphthalene, Anthracene 9-Sulfonic Acid, Anthracene 2-Sulfonic Acid, Anthracene carboxylic acid, 2-anthracene carboxylic acid, 1-anthracene carboxylic acid, anthracene-9-thiocarboxamide, 2-anthracene carboxylic acid, Anthracenesulfonyl chloride, 2-amino-1- (4-nitrophenylazo) anthracene, 7,12-dioxo-7 Dihydrobenzo [A] anthracene-6-carboxylic acid, 7-Nitrodibenzo [A] [A, H] Anthracene, 9,10-dioxo-9,10-dihydro-anthracene-2-carbaldehyde, 9 -Benzyl-1,5-dichloro-10-nitro-anthracene (9-Benzyl- 5-Dichloro-10-Nitro-Anthracene, 9-Methoxy-10-Nitro-Anthracene, 3,4-dihydroxy- Dihydroxy-9,10-dihydro-anthracene-2-sulfinate, 9-nitroanthracene, 1-dihydroxy- 1-Phenanthrene Carboxylic Acid, 2-Phenanthrene Carboxylic Acid, 4-Phenanthrene Carboxylic Acid, 9-Phenanthrene Carboxylic Acid, , 1-phenanthrene sulfonic acid, phenanthrene 2-sulfonic acid, phenanthrene 3-sulfonic acid, phenanthrene-9-thiocarboxylic acid, Phenanthrene-9-thiocarboxamide, 1,2,3,4-tetrahydro-phenanthrene-1,2-dicarboxylic acid dimethyl ester (1,2,3,4-Tetrahydro-Phenanthrene-1,2-Dicarboxylic Acid Dimethyl Ester), 9- (2-bromoacetyl) phenanthrene (9- (2-Br benzo (C) phenanthrene-5,6-dicarboxylic acid), 4-acetoxy-1-methyl-phenanthrene-2-carboxylic acid ethyl ester (C) Phenanthrene-6-Carboxylic Acid), benzo (C) phenanthrene-5-carboxylic acid (4-Acetoxy-1-Methyl-Phenanthrene-2-Carboxylic Acid Ethyl Ester) -Carboxylic acid (Benzo (C) Phenanthrene-5-carboxylic acid), 1-pyrenecarboxylic acid, pyrene-1-boronic acid, hexadecylpyrene- Hexadecylpyrene-1-sulfonamide, 1-pyrenesulfonic acid, and pyreneacetic acid.

According to an embodiment of the present invention, the electrolyte solution may include water, propylene carbonate, ethylene carbonate, dimethyl sulfoxide (DMSO), and N-methyl-2-pyrrolidone NMP). ≪ / RTI >

According to one embodiment, the ion concentration of the electrolyte solution is 0.0001M to 3M.

According to one embodiment, on the surface of the graphene flake, the anionic organic monomers are bonded by non-covalent functionalization.

According to one embodiment, separating the graphene flake from the precursor solution comprises: filtering the precursor solution; And washing the graphene flakes obtained by filtering the precursor solution.

The graphene flake dispersion solution according to an embodiment of the present invention includes a solvent and a graphene flake dispersed in the solvent, wherein the anionic organic monomers are bonded to the surface by non-covalent functionalization.

According to one embodiment, the solvent is selected from the group consisting of water, ethanol, methanol, isopropanol, tetrahydrofuran (THF), benzene, xylene, toluene, cyclohexane, N-methyl 2-pyrrolidinone ), Dimethylformamide, dimethylsulfoxide, 1,2-dimethoxyethane (DME), 1,2-dichloroethane, methylene chloride, chlorobenzene, chloroform, ethyl acetate, ethylene glycol, heptane, butanol At least one selected from the group consisting of 1-butanol, 2-butanol, 2-butanone, acetonitrile, acetone and acetic acid.

As described above, according to exemplary embodiments of the present invention, graphene flakes can be produced by an electrochemical method without an additional stripping process, and the resulting graphene flakes can have a large size and a thin thickness. Therefore, the graphene flakes can be expected to have high quality.

In addition, the graphene flakes are excellent in dispersibility to a solvent and can prevent aggregation by bonding anionic organic monomers to the surface by non-covalent functionalization. Therefore, it can be easily applied to a process using a graphene flake dispersion.

1 is a flowchart illustrating a method of manufacturing a graphene flake according to an embodiment of the present invention.
2 is a schematic cross-sectional view illustrating an electronic device to which a graphene flake dispersion manufactured according to an embodiment of the present invention is applied.
3 is a photograph of the graphene flake produced by Example 1. Fig.
4 is a graph showing the size and thickness distribution of the graphene flakes produced in Example 1. FIG.
5 is a transmission electron microscope (TEM) photograph of the graphene flake prepared in Example 1. Fig.
6 is a graph showing the results of Raman spectroscopic analysis of the graphene flakes prepared in Example 1. FIG.
FIG. 7 is a graph showing X-ray photoelectron spectroscopy (XPS) analysis results of graphene flakes prepared according to Example 1. FIG.
8 is a graph showing the results of Fourier transform infrared spectroscopy (FT-IR) analysis of the graphene flakes prepared in Example 1. FIG.
FIG. 9 is a photograph of a graphene solution prepared by Example 1 and redispersed in acetone. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. In the accompanying drawings, the dimensions of the structures are enlarged to illustrate the present invention in order to clarify the present invention.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises ", or" having ", and the like, are intended to specify the presence of stated features, integers, steps, operations, elements, or combinations thereof, , Steps, operations, elements, or combinations thereof, as a matter of principle, without departing from the spirit and scope of the invention.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

1 is a flowchart illustrating a method of manufacturing a graphene flake according to an embodiment of the present invention.

Referring to FIG. 1, a positive electrode and a negative electrode including a graphene precursor are impregnated into an electrolyte solution containing a metal salt of an anionic organic monomolecule (S10).

The electrolyte solution is an electrolyte, and includes a metal salt of the anionic organic monomolecule. Accordingly, the electrolyte solution may include an organic monoanionic anion and a metal cation.

The anionic organic monomers may have at least one anionic functional group, and may have a chain structure or a benzene derivative structure combined with the anionic functional group. For example, the chain structure may include an alkyl group having 1 or more carbon atoms or an alkylene group, and may preferably include an alkyl group or an alkylene group having 2 to 10 carbon atoms.

For example, the anionic functional group is a sulfate group (sulfate: SO ₂ ^-) sulfonate group (sulfonate: SO ₃ ^-), nitrite group (nitrite: NO ₂ ^-), nitrate group (nitrate: NO ₃ ^-), May include phosphite (PO ₃ ^3- ), phosphate group (PO ₄ ^3- ), carboxylate group (COO ^- ) or carbonate group (CO ₃ ^2- ) have. These may be used singly or in combination.

For example, the anionic organic monomers having the chain structure may be selected from the group consisting of formic acid, acetic acid, 1,2-ethanediamine, ethanesulfonate, ethyl Ethanethanesulfonate, 2- (methylamino) ethane sulfonate, 2-bromoethanesulfonate, methyl ethanesulfonate, ethane sulfonate, Ethane sulphonic acid, Ethanenitrile, 2-Hydroxy-3- (Phosphonooxy) Propanoic Acid, Glycerate 3- 2- (4-isobutylphenyl) propanoic acid phosphate), 3- (3,5-dihydroxyphenyl) -1-propionic acid sulfate (3- 5-Dihydroxyphenyl) -1-Propanoic Acid Sulphate, (3-Sulfooxyphenyl) Propanoic Acid), propanenitrile itrile propane nitrite, 3-hydroxypropane-1-sulfonic acid, succinic acid, butanoic acid, butylsulfone, Butane Phosphate, Butane Phosphate, 1,2,4-Tricarboxylic Acid (Pbtc), Succinyl Chloride, Daminozide Succinic acid bis (3,4,5-trimethoxybenzylidenehydrazide), succinic acid bis (3,4,5-trimethoxybenzylidenehydrazide), 2,2,3,3-tetrafluorosuccinic acid (2, Succinic acid 4-ethyl ester, 2-methylene-succinic acid 4-ethyl ester, 2,3-tetrafluoro-succinic acid, 4-Methyl Ester, Pentanoic Acid, Pentanyl Phosphate, Bis [4- (2,4,4-trimethyl-2-pentanyl) phenyl] hydrogenphosphate Bis [ 4,4-Trimethyl-2-Pentanyl) Phen yl] Hydrogen Phosphate, Hexanoic Acid, 3-Hexenyl Pentanoate, Hexane Carboxylic Acid, 1-Hexanesulfonic Acid, Hexylphosphonic acid, hexylphosphonic acid, butyl 4-nitrophenyl hexylphosphonate, hexylphosphonic dichloride, methyl 4-methylumbelliferyl hexylphosphate, heptylcarboxylic acid ( Heptyl Carboxylic Acid, 1-Heptanesulfonic Acid, 4-Heptylbenzoic Acid, Propylphosphonic Acid and Bicyclo [2.2.1] Heptane-1-Carboxylic Acid (Bicyclo [2.2.1] Heptane-1-Carboxylic Acid, Heptane-2-Carboxylic Acid, Heptyl Acetate, Octane Carboxylic Acid, Bicyclo [2.2.1] -1-carboxylic acid (Bicyclo [2.2.2] Octane-1-Carboxylic Acid), 4- (4-pentylbicyclo [2.2.2] octane-1-carboxylic acid), octylphosphonic acid, octylsulfonic acid, 1-octanesulfonic acid Octane sulfonic acid, 4-octylbenzenesulfonic acid, 1-octanesulfonate, octylphosphonic acid, 1- (octane-1-sulfinyl) Octane-1-Sulfinyl-Octane, Octane-2-Sulfonate, Dodecyl Sulfate, Dodecyl Carboxylic Acid, Dodecyl Nitrate, Dodecyl 2-Bromothiophene-4-Carboxylate, 4-Dodecylbenzenesulfonic Acid, Dodecylsulfonic Acid, Dodecyl Sulfonic Acid, Dodecylbenzenesulfonate, N-Dodecylphosphonic Acid, 1-Dodecylphosphonic Acid, and the like may be used. .

For example, the anionic organic monomers having the benzene derivative structure may be selected from the group consisting of benzoic acid, 4-aminobenzoic acid, benzenesulfonic acid, benzene sulfonamide, Alkylbenzenesulfonate, phenylphosphate, dodecylbenzenesulphonic acid, 2-formyl-benzene-1,4-disulfonic acid, Disulfonic Acid, Naphthalene Sulfonic Acid, Naphthalene Carboxylic Acid, Naphthoquine Phosphate, Naphthalene Acetic Acid, Naphthalene Phosphoric Acid, 1-Naphthoic Acid, (1-Naphthoic Acid), 4-amino-1-naphthalenesulfonic acid, 6- (P-Tolyldino) -2-naphthalenesulfonic acid, -2-Naphthalenesulfonic acid), 4-hydroxy-1-naphthalene sulfonic acid), 4-amino-1-naphthalenesulfonate, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4 Dimethoxy-naphthalene-1-carbaldehyde, 4-benzyloxy-naphthalene-1-sulfonylchloride (4-benzyloxy- 4-Chloro-Naphthalene-1-Sulfonyl Chloride, 5-Amino-Naphthalene-1-Sulfonyl Chloride, , 5-bromo-naphthalene-1-sulfonyl chloride, 5-formylamino-naphthalene-1-sulfonyl chloride ), 5-Methylamino-Naphthalene-1-sulfonyl Chloride, (1-Naphthalene) Trifluoroborate, 7-hydroxy- , 2,3 , 4-tetrahydro-naphthalene-2-carboxylic acid (7-hydroxy-naphthalene-2-carboxylic acid Oxo-1,2,3,4-tetrahydro-naphthalene-2-carboxylic acid (7-Bromo-3-Hydroxy- -Naphthalene-2-carboxylic acid), 5 - [(2-ethyl-piperidine-1-carbonyl) -amino] -naphthalene- Carbonyl) -Amino] -Naphthalene-1-sulfonyl Chloride, 5- (2,2,2-trifluoro-acetylamino) -naphthalene- 1 -sulfonylchloride (5- (2,2,2- (Acetyl-Ethyl-Amino) -Naphthalene-1-sulfonyl Chloride), 3- ( (Naphthalene-2-sulfonyl) -propionic acid, 2- (propylsulfonyl) naphthalene, anthracene 9-sulfonic acid 9-sulfonic acid, anthracene 2-sulfonic acid, anthracene 1-sulfonic acid, 9-anthracene carboxylic acid, 2-anthracenecarboxylic acid, Anthracene Carboxylic Acid, 1-Anthracene Carboxylic Acid, Anthracene-9-Thiocarboxamide, 2-Anthracenesulfonyl Chloride, 2- Amino-1- (4-nitrophenylazo) anthracene, 7,12-dioxo-7,12-dihydrobenzo [A] anthracene-6-carboxylic acid ( 7,12-Dioxo-7,12 Dihydrobenzo [A] Anthracene-6-Carboxylic Acid), 7-Nitrodibenzo [A, H] Anthracene, 9,10- 9,10-dihydro-anthracene-2-carbaldehyde, 9-benzyl-1,5-dichloro-10-nitro-anthracene 9-Benzyl-1,5-Dichloro-10-nitro-anthracene), 9-methoxy-10- 9-methoxy-10-nitro-anthracene, 3,4-dihydroxy-9,10-dioxo-9,10-dihydroxy- 10-Dioxo-9,10-Dihydro-Anthracene-2-Sulfinate, 9-Nitroanthracene, 1-Phenanthrene Carboxylic Acid, 2-Phenanthrene Carboxylic Acid Acid), 4-Phenanthrene Carboxylic Acid, 9-Phenanthrene Carboxylic Acid, 1-Phenanthrene Sulfonic Acid, Phenanthrene Sulfonic Acid, Phenanthrene 2-sulfonic acid, Phenanthrene 3-sulfonic acid, Phenanthrene-9-thiocarboxamide, 1,2,3,4-tetrahydro-phenanthrene- 1,2-Dicarboxylic Acid Dimethyl Ester, 9- (2-bromoacetyl) phenanthrene (9- (2- Bromoacetyl) Phenanthrene), benzo (C) phenanthrene-5,6-dicarboxy (4-acetoxy-1-methyl-phenanthrene-2-carboxylic acid ethyl ester Benzo (C) phenanthrene-6-carboxylic acid (Benzo (C) Phenanthrene-6-carboxylic acid), benzo (C) phenanthrene- 1-pyrenesulfonic acid (1-pyrenecarboxylic acid), pyrene-1-boronic acid, hexadecylpyrene-1-sulfonamide, ), Pyreneacetic acid, and the like.

For example, the metal salt of the anionic organic monomolecule may include an alkali metal such as lithium, sodium, potassium, calcium, and the like.

For example, the metal salt of an anionic organic monomolecule having the chain structure may be selected from the group consisting of sodium ethanesulfonate, disodium succinate, sodium succinate dibasic hexahydrate, Sodium pentanoate, sodium pentyl sulfate, sodium 1-pentyl sulfate, 1-hexanesulfonic acid sodium, 1-heptanesulfonic acid, 1-Heptanesulfonic Acid Sodium, Lithium Dodecyl Sulfate, and the like. These may be used singly or in combination.

For example, the metal salt of an anionic organic monomolecular molecule having the benzene derivative structure may be selected from the group consisting of sodium dodecylbenzenesulfonate, potassium phenylsulfate, disodium phenyl phosphate, Sodium benzoate, sodium phenyphosphate dibasic dihydrate, sodium (3-bromo-phenyl) -acetate, sodium benzoate, sodium benzoate, Sodium Chloro (Phenyl) Methanesulfonate, Sodium Diphenylamine-4-Sulfonate, Sodium 2-Naphthalenesulfonate, 2-naphthalenesulfonate, sodium 1-naphthalenesulfonate, sodium 2-amino-1-naphthalenesulfonate, sodium 7-amino-2-naphthalenesulfonate, Carbonate may include (Sodium 7-Amino-2-Naphthalenesulfonate), sodium 3-amino-7-sulfo-2-naphthalene sulfonate (Sodium 3-Amino-7-Sulfo-2-Naphthalenesulfonate) and the like. These may be used singly or in combination.

However, the metal salt of the anionic organic monomolecular molecule is not limited to the above specific examples, and may include various combinations of the anionic organic monomers and the alkali metal.

Preferably, the anionic organic monomolecular molecule may be an anionic organic monomolecular molecule having a benzene derivative structure. An anionic organic monomolecular molecule having a benzene derivative structure can strongly bond the graphene precursor to the graphene precursor by pi interaction, thereby enhancing the separation efficiency of the graphene flake.

The electrolyte solution may include a solvent for dissolving the electrolyte. For example, the solvent may include water, propylene carbonate, ethylene carbonate, dimethyl sulfoxide (DMSO), and N-methyl-2-pyrrolidone (NMP) , Which may be used alone or in combination.

For example, the ion concentration of the electrolyte may be 0.0001 M to 3 M, and the defect rate of graphene prepared according to the ion concentration can be controlled.

The graphene precursor may include natural graphite, artificial graphite, carbon fiber, and the like. For example, the graphite may comprise keyed graphite. Kishi graphite is a kind of natural graphite having high crystallinity and relatively large crystal size, which can improve the size of graphene flakes finally produced.

The cathode may be a counter electrode of the electrode including the graphene precursor and may include a common electrode material such as metal, carbon, and the like.

Next, an intercalating compound is formed by applying a positive voltage and a negative voltage to the positive electrode and the negative electrode, respectively, and bonding the graphene precursor of the positive electrode and the anionic organic molecule to each other (S20).

As the anionic organic monomolecules are inserted into the graphene precursor (graphite) and the intercalation compound is formed by the non-covalent functionalization, the van der Waals bond between the graphite layers weakens and the electrostatic charge due to the newly generated surface charge The graphene flake can be peeled off from the graphene precursor by the magic repulsive force. Thus, an electrolyte solution containing graphene flakes can be obtained.

For example, the voltage may be a direct current voltage and the operating voltage may range from 100 mV to 20 V, where the current value may range from 1 mA to 5 A.

The time for applying the voltage may vary depending on the set voltage and current value, and may be, for example, 30 seconds to 7 days.

Next, the graphene flakes are separated from the electrolyte solution (S30).

For example, to separate the graphene flakes, the remaining electrolyte can be removed through a filtration and washing process using a filtration device such as a vacuum filtration device. The washing process may be repeatedly washed using a washing solution containing distilled water and / or alcohol.

Thereafter, the graphene flakes, which have been filtered and washed, can be redispersed in a solvent to obtain a dispersion solution containing the graphene flakes.

In exemplary embodiments, the solvent is selected from the group consisting of water, ethanol, methanol, isopropanol, tetrahydrofuran (THF), benzene, xylene, toluene, cyclohexane, N-methyl 2-pyrrolidinone ), Dimethylformamide, dimethylsulfoxide, 1,2-dimethoxyethane (DME), 1,2-dichloroethane, methylene chloride, chlorobenzene, chloroform, ethyl acetate, ethylene glycol, heptane, butanol Butanone, acetonitrile, acetone, acetic acid, and the like, which may be used alone or in combination.

The graphene flakes obtained according to the embodiments of the present invention can be obtained by an electrochemical method without an additional stripping process.

Further, the graphene flakes may have a large size, for example, a size of 50 mu m or larger, preferably 100 mu m or larger. In addition, the flakes may have a thin thickness, so as to have substantially the nature of graphene. Therefore, the graphene flakes can be expected to have high quality.

In addition, the graphene flakes are excellent in dispersibility to a solvent and can prevent aggregation by bonding anionic organic monomers to the surface by non-covalent functionalization. Therefore, it can be easily applied to a process using a graphene flake dispersion.

2 is a schematic cross-sectional view illustrating an electronic device to which a graphene flake dispersion manufactured according to an embodiment of the present invention is applied. For example, FIG. 2 shows an electronic device including a barrier film formed using the dispersion solution prepared by the process described with reference to FIG. 1, and the electronic device may be, for example, a display device.

Referring to FIG. 2, the electronic device may include a PET substrate 100, a barrier film 110, a display panel 120, and a sealing member 130.

The barrier film 110 may be formed using the dispersion solution including graphene flakes peeled by the process described with reference to Fig. For example, the dispersion solution may be applied on the PET substrate 100 or the display panel 120, and the barrier film 110 may be formed through a drying process. In addition, a predetermined patterning process for the barrier film 110 may be further performed.

The barrier film 110 may include graphene. The gas barrier property of the display panel can be improved by the barrier film (110). For example, graphenes can be combined in a uniform film form to block oxygen and moisture. Thus, an electronic device with reduced defects such as deterioration in performance through reaction of oxygen with moisture can be obtained.

The display panel 120 may include a display circuit board including, for example, a thin film transistor (TFT). The display panel 120 may include, for example, a liquid crystal display (LCD) panel and an organic light emitting display (OLED) panel.

The sealing member 130 may include various covers, bezels, sealants, and the like for protecting the display device.

Hereinafter, a method for producing graphene flakes according to exemplary embodiments will be described in detail with reference to specific experimental examples. The following experimental examples are merely illustrative, and the embodiments of the present invention are not limited to the above experimental examples.

Example 1

1) Electrolyte manufacturing

2.3 g of sodium 2-naphthalene sulfonate was dissolved in 100 ml of distilled water to prepare an electrolyte having a concentration of 0.1 mole.

2) Separation of graphene flake using electrochemical stripping

80 ml of the prepared electrolyte was immersed in a 100 ml beaker, and then the graphite was placed on the anode (+) using tweezers having conductivity. Place a platinum wire on the negative (-) side. The distance between the anode and the cathode was about 10 mm. Each electrode was passed through a DC voltage, and a voltage of 3 V was applied at a current value of about 10 mA and maintained for 90 minutes to obtain a solution in which graphene flakes were dispersed.

3) Washing and redispersing of the prepared graphene flakes

The electrolyte solution containing the graphene flakes was filtered using a filtration filter and then repeatedly washed with distilled water and a solvent of acetone and alcohols in an amount of 5 times as much as the volume of the graphene flak electrolyte solution. Acetone was dispersed through an ultrasonic process.

3 is a photograph of the graphene flake produced by Example 1. Fig. Specifically, (a) is an optical microscope photograph, (b) is a scanning electron microscope (SEM) photograph, and (c) is an atomic force microscope (AFM) photograph.

Referring to FIG. 3, it can be seen that the graphene flakes produced according to Example 1 can have a size of more than 100 micrometers. Also, referring to the atomic force microscope photograph, it can be seen that the thickness of the graphene flake was about 0.7 nm, through which the single layer graphene was obtained.

4 is a graph showing the size and thickness distribution of the graphene flakes produced in Example 1. FIG.

Referring to FIG. 4, it can be seen that about 88% of the graphene flakes prepared in Example 1 have a size of 50 μm or more and 50% have a size of 80 μm or more. Also, it can be seen that about 57% of the graphene flakes have a thickness of 2 nm or less and 90% or more have a thickness of 5 nm or less.

5 is a transmission electron microscope (TEM) photograph of the graphene flake prepared in Example 1. Fig.

Referring to FIG. 5, it can be seen that the graphene flakes prepared according to Example 1 have a size of 10 μm or more and the number of layers is 1 to 4 layers.

6 is a Raman spectroscopic analysis result of the graphene flake prepared in Example 1. Fig.

Referring to FIG. 6, it can be seen that the ratio of the D-peak (~ 1350 cm ^-1 ) to the G-peak (~ 1600 cm ^-1 ), which is an index of defect, is about 0.13. This is lower than that of the graphene flakes produced by the conventional oxidation-reduction method or the conventional electrochemical method using the sulfuric acid electrolyte. Therefore, it can be confirmed that the graphene flakes of high quality were produced by the method of Example 1.

FIG. 7 is a graph showing X-ray photoelectron spectroscopy (XPS) analysis results of graphene flakes prepared according to Example 1. FIG. Specifically, (a) is a graph showing the total element content, (b) is an enlarged graph of a peak corresponding to carbon, (c) is an enlarged graph of a peak corresponding to oxygen, Which is an enlarged graph.

First, referring to (a), it can be seen that the graphene flakes prepared in Example 1 have increased oxygen (O) and sulfur (S) contents as compared with graphite. Further, referring to (c) and (d), it can be confirmed that the detected oxygen and sulfur components originated from the sulfonate group (SO ₃ ^- ). Thus, it can be seen that naphthalene-2-sulfonate, which is non-covalently functionalized, is bound to the graphene flake surface.

(b), it can be confirmed that the ratio of the peak (248.5 eV) corresponding to the sp2C = C bond showing the intrinsic structure of graphene is about 81% or more, and the defect rate on the surface is low.

8 is a graph showing the results of Fourier transform infrared spectroscopy (FT-IR) analysis of the graphene flakes prepared in Example 1. FIG.

8, S-O and S = O peaks corresponding to the characteristic peaks of naphthalene-2-sulfonate were observed in the graphene flakes produced in Example 1, respectively. On the other hand, the hydroxyl group (OH < - >) formed upon the occurrence of surface defects of graphene is observed very poorly.

Thus, it can be confirmed that the ratio of the naphthalene-2-sulfonate to the graphene flake prepared in Example 1 was non-covalently functionalized and the degree of the defect on the surface of the graphene was very low.

9 is a photograph of the graphene flakes prepared by Example 1 and redispersed in acetone.

Referring to FIG. 9, it can be seen that the graphene produced by the non-covalent functional group described above can be dispersed in an organic solvent such as acetone without aggregation.

Thus, it can be seen that a high-quality graphene flake can be mass-produced in a safer and simpler process by using an electrochemical process in a metal ion-anion monomolecular electrolyte.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims. It can be understood that it is possible.

The graphene flakes or the dispersion solution containing the same produced according to the above-described exemplary embodiments can be applied to various light / high strength composite materials having improved electrical / mechanical properties, heat dissipation materials, materials for nano ink, secondary batteries, fuel cells, etc. Electrode materials and barrier / coating materials.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims. It can be understood that it is possible.

100: PET substrate 110: barrier film
120: display panel 130: sealing member

Claims (13)

Impregnating an anode and a cathode containing a graphene precursor into an electrolyte solution containing a metal salt of an anionic organic monomolecule;
Applying a voltage to the positive electrode and the negative electrode to form an intercalation compound of the anionic organic monomolecule and the graphene precursor, thereby peeling the graphene flake from the graphene precursor; And
Separating the graphene flake from a precursor solution comprising the graphene flake,
Wherein the anionic organic monomolecule comprises at least one anionic functional group and a benzene derivative structure bonded thereto, wherein the anionic organic monomolecule is bonded to the surface of the graphene flake by non-covalent functionalization Method of manufacturing graphene flakes. The method of claim 1, wherein the graphene precursor comprises at least one selected from the group consisting of natural graphite, artificial graphite, and carbon fiber. delete The method according to claim 1, wherein the anionic functional group is selected from the group consisting of sulfate (SO ₂ ^- ) sulfonate (SO ₃ ^- ), nitrite (NO ₂ ^- ), nitrate (NO ₃ ^- ), A phosphite (PO ₃ ^3- ), a phosphate group (PO ₄ ^3- ), a carboxylate group (COO ^- ) and a carbonate group (CO ₃ ^2- ) ≪ / RTI > wherein at least one selected from the group consisting < RTI ID = 0.0 > of: < / RTI > delete The method of claim 1, wherein the anionic organic monomolecule is selected from the group consisting of benzoic acid, 4-aminobenzoic acid, benzenesulfonic acid, benzene sulphonamide, 2-Formyl-Benzene-1,4-Disulfonic Acid, 2-formyl-benzene-1,4-disulfonic acid, Naphthalene Sulfonic Acid, Naphthalene Carboxylic Acid, Naphthoquine Phosphate, Naphthalene Acetic Acid, Naphthalene Phosphoric Acid, 1-Naphthoic Acid, 1- Naphthoic Acid), 4-amino-1-naphthalenesulfonic acid, 6- (P-Toluidino) -2-naphthalenesulfonic acid Naphthalenesulfonic acid), 4-hydroxy-1-naphthalenesulfonic acid, 4-amino 1-naphthalenesulfonate, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,8-dimethoxy-naphthalene sulfonate, 4-benzyloxy-naphthalene-1-sulfonyl chloride, 4-chloro-naphthalene-1-carbaldehyde, 5-amino-naphthalene-1-sulfonyl chloride, 5-bromo-naphthalene-1-sulfonyl chloride, 5-Formylamino-Naphthalene-1-Sulfonyl Chloride, 5-Bromo-Naphthalene-1-Sulfonyl Chloride, Naphthalene-1-sulfonyl chloride, (1-naphthalene) Trifluoroborate, 7-hydroxy-1,2,3,4- Tetrahydro- Hydroxy-naphthalene-2-carboxylic acid (7-Bromo-3-carboxylic acid, 7-hydroxy-1,2,3,4-tetrahydro- -Hydroxy-Naphthalene-2-carboxylic acid), 4-oxo-1,2,3,4-tetrahydro-naphthalene- (2-Ethyl-piperidine-1-carbonyl) -amino] -naphthalene-1-sulfonyl chloride (5 - [ -Naphthalene-1-sulfonyl Chloride), 5- (2,2,2-trifluoro-acetylamino) -naphthalene-1-sulfonylchloride (5- (2,2,2-Trifluoro-Acetylamino) -Naphthalene- 1-sulfonyl chloride, 5- (acetyl-ethyl-amino) -naphthalene-1-sulfonyl chloride, 3- (naphthalene- 2-sulfonyl) -propionic acid, 2- (propylsulfonyl) naphthalene, anthracene 9-sulfonic acid, anthracene- Anthracene 2-sulfonic acid, anthracene 1-sulfonic acid, 9-anthracene carboxylic acid, 2-anthracene carboxylic acid, 1-anthracene carboxylic acid, anthracene-9-thiocarboxamide, 2-anthracenesulfonylchloride, 2-amino-1- (4 -Nitrophenylazo anthracene, 7,12-dioxo-7,12-dihydrobenzo [A] anthracene-6-carboxylic acid (7,12-Dioxo- 7,12 Dihydrobenzo [A] Anthracene-6-Carboxylic Acid), 7-Nitrodibenzo [A, H] Anthracene, 9,10-dioxo-9,10- 9-Benzyl-1, 2-carbaldehyde, 9-benzyl-1, 5-dichloro-10-nitro-anthracene, 5-Dichloro-10-Nitro-Anthracene, 9-Methoxy-10-Nitro-An thracene, 3,4-dihydroxy-9,10-dioxo-9,10-dihydroxy-9,10-Dioxo-9,10-Dihydro- Anthracene-2-Sulfinate, 9-Nitroanthracene, 1-Phenanthrene Carboxylic Acid, 2-Phenanthrene Carboxylic Acid, 4-Phenanthrenecarboxylic Acid -Phenanthrene Carboxylic Acid, 9-Phenanthrene Carboxylic Acid, 1-Phenanthrene Sulfonic Acid, Phenanthrene 2-Sulfonic Acid, Sulfonic acid, Phenanthrene-9-thiocarboxamide, 1,2,3,4-tetrahydro-phenanthrene-1,2-dicarboxylic acid dimethyl ester (1,2,3,4-Tetrahydro-Phenanthrene-1,2-Dicarboxylic Acid Dimethyl Ester), 9- (2-Bromoacetyl) Phenanthrene, 5,6-dicarboxylic acid (Benzo (C) Phenanthrene-5, 6-Dicarboxylic Acid, 4-Acetoxy-1-Methyl-Phenanthrene-2-Carboxylic Acid Ethyl Ester, Benzo (C) Phenanthrene- Benzo (C) phenanthrene-5-carboxylic acid, benzo (C) phenanthrene-5-carboxylic acid, 1-pyrenecarboxylic acid, (1-pyrenesulfonic acid) and pyreneacetic acid (Pyrene-1-boronic acid, hexadecylpyrene-1-sulfonamide, ≪ / RTI > wherein at least one selected from the group consisting < RTI ID = 0.0 > of: < / RTI > The electrolyte solution according to claim 1, wherein the electrolyte solution is selected from the group consisting of water, propylene carbonate, ethylene carbonate, dimethyl sulfoxide (DMSO), and N-methyl-2-pyrrolidone NMP). ≪ Desc / Clms Page number 20 > The method of claim 1, wherein the ionic concentration of the electrolyte solution is 0.0001 M to 3 M. delete 2. The method of claim 1, wherein separating the graphene flake from the precursor solution comprises:
Filtering the precursor solution; And
And washing the graphene flakes obtained by filtering the precursor solution. menstruum; And
A graphene flake dispersion solution comprising graphene flakes produced by any one of claims 1, 2, 4, 6, 7, 8, and 10.
delete The method of claim 11, wherein the solvent is selected from the group consisting of water, ethanol, methanol, isopropanol, tetrahydrofuran (THF), benzene, xylene, toluene, cyclohexane, N-methyl 2-pyrrolidinone ), Dimethylformamide, dimethylsulfoxide, 1,2-dimethoxyethane (DME), 1,2-dichloroethane, methylene chloride, chlorobenzene, chloroform, ethyl acetate, ethylene glycol, heptane, butanol Wherein the graphene flake dispersion solution contains at least one selected from the group consisting of 1-butanol, 2-butanol, 2-butanone, acetonitrile, acetone and acetic acid.

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