Method of preparing carbon aerogel precursor, carbon aerogel precursor prepared thereby, and carbon aerogel

Abstract

The present invention relates to a carbon aerogel precursor, a preparation method thereof and a carbon aerogel prepared thereby and, more particularly, to a carbon aerogel precursor which can be converted into a carbon aerogel that exhibits excellent specific surface area and physical properties by using a binder that has a low carbonization ratio and is capable of performing phase conversion while using a carbon material having physical properties such as diameter, length and the like that are not adjusted, a preparation method thereof, and a carbon aerogel prepared thereby.

Claims

1. A method of preparing a carbon aerogel precursor, the method comprising the steps of: mixing a carbon material and a dispersant with a solvent to prepare a carbon material dispersion; adjusting concentration of the carbon material dispersion; mixing a binding agent with the carbon material dispersion to provide a mixed solution; dispersing the mixed solution to obtain a gelated mixed solution; and dipping the gelated mixed solution in ethanol to remove the dispersant, wherein adjusting the concentration of the carbon material dispersion comprises evaporating the solvent, and wherein the binding agent is at least one of gelatin, cellulose or chitosan.

2. The method of claim 1, wherein the carbon material is selected from the group consisting of a carbon nanotube, a graphene, an oxide graphene, and a carbon fiber.

3. The method of claim 1, wherein the carbon material has a diameter of 0.8 nm or more and a length of 100 nm or more, and a carbon material dispersion comprising the carbon material has a concentration of 0.001 to 30 wt %.

4. The method of claim 1, wherein the solvent is water or an organic solvent selected from the group consisting of methyl alcohol (MeOH), ethyl alcohol (EtOH), propyl alcohol (PA), isopropyl alcohol (IPA), butyl alcohol, ethylene glycol (EG), 1,2-dichlorobenzene, dimethyl formamide (DMF), dimethyl acetamide (DMAc), methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), butyl cellosolve (BC), butyl cellosolve acetate (BCA), n-methyl-2-pyrrolidone (NMP), ethyl acetate (EA), butyl acetate (BA), acetone, cyclohexanone, and toluene.

5. The method of claim 1, wherein the dispersant is an anionic dispersant selected from the group consisting of sodium dodecyl sulfate (SDS), lithium dodecyl sulfate (LDS), sodium dodecyl sulfate (NaDDS), sodium dodecyl sulfonate (SDSA) and sodium dodecylbenzene sulfonate (SDBS) that are alkyl sulfate-based compounds, or a cationic dispersant selected from the group consisting of cetyltrimethyl ammonium chloride (CTAC), cetyltrimethyl ammonium bromide (CTAB), and dodecyl-trimethyl ammonium bromide (DTAB), or a nonionic dispersant selected from the group consisting of glycerol monostearate, sorbitan monooleate, polyvinyl alcohol (PVA), polymethyl acrylate (PMA), methyl cellulose (MC), carboxyl methyl cellulose (CMC), Gum Arabic (GA), polysaccharide, polyethyleneimine (PEI), polyvinylpyrrolidone (PVP), and polyethylene oxide (PEO)-poly(ethylene oxide)-poly(butylene oxide) terpolymer.

6. The method of claim 1, wherein the binding agent is mixed in an amount of 50 to 300 parts by weight per the total weight of the carbon material dispersion of 100 parts by weight.

7. The method of claim 1, wherein the binding agent has a carbon yield upon carbonization of 5 to 40%.

8. The method of claim 1, wherein the step of mixing the binding agent with the carbon material dispersion further comprises additionally mixing a carbon precursor with the binding agent and the carbon material dispersion.

9. The method of claim 8, wherein the carbon precursor is selected from the group consisting of (i) a saccharide selected from the group consisting of a monosaccharide, a disaccharide, an oligosaccharide, derivatives thereof, and a random combination thereof, (ii) a polymer carbohydrate, derivatives of the polymer carbohydrate, a non-carbohydrate synthetic polymer or a random combination thereof, and polydopamine.

10. The method of claim 8, wherein the carbon precursor is a monosaccharide selected from the group consisting of glucose, fructose, hydrates thereof, syrups thereof, and combinations thereof.

11. The method of claim 8, wherein the carbon precursor is a polysaccharide selected from the group consisting of maltose, sucrose, hydrates thereof, syrups thereof, and combinations thereof.

12. A method of preparing a carbon aerogel, the method comprising the steps of: preparing a carbon material dispersion by mixing a carbon material and a dispersant with a solvent; adjusting concentration of the carbon material dispersion; providing a mixed solution by mixing a binding agent with the carbon material dispersion; obtaining a gelated carbon aerogel precursor by dispersing the mixed solution; removing the dispersant and obtaining a dispersant-removed carbon aerogel precursor by dipping the gelated carbon aerogel precursor in ethanol; and obtaining a dried carbon aerogel by drying the dispersant-removed carbon aerogel precursor.

13. The method of claim 12, further comprising the step of carbonizing the carbon material and the binding agent by heat-treating the carbon aerogel dried in the step of drying the dispersant-removed carbon aerogel precursor.

14. A method of producing a carbon aerogel graphene composite, the method comprising the steps of: preparing a carbon material dispersion by mixing a carbon material and a dispersant with a solvent; providing a mixed solution by mixing a binding agent with the carbon material dispersion; obtaining a gelated carbon aerogel precursor by dispersing the mixed solution; mixing a graphene oxide with the gelated carbon aerogel precursor to prepare a mixed solution; performing a spinning process of the mixed solution, thereby spinning the mixed solution to manufacture a nanofiber; and heat-treating the nanofiber.

15. The method of claim 14, further comprising the step of adjusting concentration of the carbon material dispersion before the step of providing a mixed solution by mixing a binding agent with the carbon material dispersion.

16. The method of claim 14, further comprising the step of removing the dispersant and obtaining a dispersant-removed carbon aerogel precursor by dipping the gelated carbon aerogel precursor in ethanol before the step of mixing a graphene oxide with the carbon aerogel precursor to prepare a mixed solution.

17. The method of claim 14, wherein the binding agent has a carbon yield upon carbonization of 5 to 40% during carbonization.

18. The method of claim 14, wherein the carbon precursor is additionally mixed in an amount ratio of 0.1 to 1,000 parts by weight per 100 parts by weight of the carbon material dispersion in the step of providing a mixed solution by mixing a binding agent with the carbon material dispersion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates carbon aerogel precursors prepared by embodiments of the present invention in the state of a jelly which does not flow even when they are turned upside down as the carbon aerogel precursors are gelated.

(2) FIG. 2 illustrates a cylindrical mold manufactured to prepare carbon aerogels according to embodiments of the present invention.

(3) FIG. 3 illustrates a process of removing a dispersant by dipping carbon aerogel precursors according to embodiments of the present invention in ethanol.

(4) FIG. 4 and FIG. 5 illustrate carbon aerogel precursors dried by embodiments of the present invention and scanning electron microscope (SEM) photographs of the dried carbon aerogel precursors.

(5) FIG. 6 illustrates results of measuring SEM photographs of carbon aerogels prepared by embodiments of the present invention.

(6) FIG. 7 illustrates results of measuring binding energies with respect to carbon aerogels prepared by embodiments of the present invention.

(7) FIG. 8 illustrates results of measuring specific surface areas of the carbon aerogels prepared by embodiments of the present invention.

(8) FIG. 9 illustrates results of measuring pore size distributions of the carbon aerogels prepared by embodiments of the present invention.

(9) FIG. 10 and FIG. 11 are a carbon aerogel precursor dried by an embodiment of the present invention and SEM photographs of the carbon aerogel precursor.

(10) FIG. 12 is SEM photographs of a carbon aerogel heat-treated by an embodiment of the present invention.

(11) FIG. 13 and FIG. 14 are transmission electron microscope (TEM) photographs of a carbon aerogel prepared by an embodiment of the present invention.

(12) FIG. 15 is results of measuring binding energies of a carbon aerogel prepared by an embodiment of the present invention.

(13) FIG. 16 is results of measuring specific surface areas of the carbon aerogels prepared by embodiments of the present invention.

(14) FIG. 17 is results of measuring pore size distributions of the carbon aerogels prepared by embodiments of the present invention.

(15) FIG. 18 is optical microscope photographs of a carbon aerogel graphene composite produced by an embodiment of the present invention.

(16) FIG. 19 is a tensile strength measurement result of the carbon aerogel graphene composite produced by an embodiment of the present invention.

(17) FIG. 20 and FIG. 21 are SEM photographs showing inner section and surface of a carbon aerogel graphene composite before reduction produced by an embodiment of the present invention.

(18) FIG. 22 is SEM photographs of the carbon aerogel graphene composite produced by an embodiment of the present invention.

(19) FIG. 23 and FIG. 24 are cyclic voltammetry measurement results in a three-electrode system including the carbon aerogel graphene composite produced by an embodiment of the present invention.

(20) FIG. 25 is a cyclic voltammetry measurement result in a super capacitor including the carbon aerogel graphene composite produced by an embodiment of the present invention.

(21) FIG. 26 is a charging capacity measurement result in the super capacitor including the carbon aerogel graphene composite produced by an embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

(22) Hereinafter, the present invention will be described more in detail by examples. However, the present invention is not limited by the following examples.

(23) [Preparation 1 of Carbon Aerogel Precursors and Carbon Aerogels]

(24) Preparation of a CNT Dispersion

(25) After adding sodium dodecylbenzene sulfonate (SDBS) as a dispersant to distilled water as a dispersion medium to obtain a mixed solution, a carbon nanotube was uniformly dispersed in the mixed solution at a ratio of 0.5 wt %.

(26) After applying ultrasonic waves to a mixed solution of the carbon nanotube and a solvent and dispersing the carbon nanotube in the solvent for 2 hours to obtain a carbon nanotube dispersion, a centrifugation process of the carbon nanotube dispersion was performed to separate a supernatant from the carbon nanotube dispersion.

(27) A carbon nanotube dispersion was prepared by evaporating the solvent from the separated supernatant, thereby adjusting concentration of the carbon nanotube dispersion to 1.0 wt %.

(28) Preparation of a Gelatin Solution

(29) After mixing 3 mg of gelatin with 1 ml of distilled water, a gelatin solution was prepared by stirring the gelatin in the water until the gelatin was fully dissolved in the water at about 50° C.

(30) Preparation and Gelation of a CNT-Gelatin Mixed Solution

(31) The previously prepared gelatin solution was mixed with the previously prepared CNT dispersion to obtain mixed solutions. At this time, mixing ratios of the CNT dispersion and the gelatin solution are shown in the following table 1.

(32) TABLE-US-00001 TABLE 1 CNT dispersion:Gelatin solution Example 1 1:2 Example 2 1:1 Example 3 2:1

(33) Then, gelated CNT-gelatin mixed solutions in the form of a jelly were obtained by uniformly dispersing the gelatin solution in the CNT dispersion while applying ultrasonic waves to the mixed solutions to obtain CNT-gelatin mixed solutions, and leaving alone the CNT-gelatin mixed solutions at temperatures including room temperature, 3° C. and 60° C. for 1 hour, thereby gelating the CNT-gelatin mixed solutions.

<Experimental Example> Phase Change Analysis of CNT-Gelatin Mixed Solutions

(34) After leaving alone a carbon aerogel precursor obtained in an embodiment of the present invention at temperatures including room temperature, 3° C. and 60° C. for 1 hour, phase changes appearing according to the temperatures were analyzed, and results of analyzing the phase changes are illustrated in FIG. 1.

(35) As shown in FIG. 1, it can be seen that a carbon aerogel precursor obtained by mixing gelatin with the CNT dispersion is gelated if the temperatures are relatively lowered while the carbon aerogel precursor is converted into a liquid phase if the temperatures are increased.

(36) The carbon aerogel precursor is converted into a liquid phase by heat if the temperatures are increased in case of a low CNT mixing ratio while a gelation degree of the carbon aerogel precursor is shown to be high if the temperatures are lowered. On the other hand, it can be confirmed that the gelation degree of the carbon aerogel precursor is low although the temperatures are lowered in case of a high CNT mixing ratio.

(37) Further, it can be seen in case of a sample 2 having a mixing ratio of CNT to gelatin of 1:1 that the carbon aerogel precursor is fully gelated if the temperatures are low, and the carbon aerogel precursor is converted into a liquid phase if the temperatures are increased.

(38) Removal of a Dispersant

(39) After increasing temperatures of the foregoing obtained gelated CNT-gelatin mixed solutions to 200° C., thereby forming the gelated CNT-gelatin mixed solutions in a liquid phase, the gelated CNT-gelatin mixed solutions formed in the liquid phase were put into the cylindrical mold illustrated in FIG. 2 to form the gelated CNT-gelatin mixed solutions in a cylindrical shape.

(40) After preparing ethanol solutions having concentrations of 10%, 20%, 40%, 80% and 100%, the gelated CNT-gelatin mixed solutions were sequentially dipped in the ethanol solutions while replacing the ethanol solutions from an ethanol solution having a lowest concentration to an ethanol solution having a highest concentration once every three hours. In this manner, carbon aerogel precursors were finally obtained by removing SDBS used as the dispersant in the foregoing preparation example in order to use the carbon material dispersion.

(41) A process of dipping the carbon aerogel precursors in ethanol to remove the dispersant is illustrated in FIG. 3.

(42) Drying Process

(43) Carbon aerogels were prepared by drying the carbon aerogel precursors while substituting ethanol impregnated in the previously dispersant-removed carbon aerogel precursors with carbon dioxide through a critical point dryer (CPD) process.

(44) The CPD process in embodiments of the present invention was progressed in a method of drying the carbon aerogel precursors without damages to shape of the aerogels by blowing away carbon dioxide in the critical point state after substituting ethanol in the gelated carbon aerogel precursors with liquid carbon dioxide.

(45) SEM photographs of carbon aerogels dried by the CPD process are illustrated in FIG. 4.

(46) Carbonization Process

(47) Carbon aerogels were prepared by heat-treating each of the previously dried carbon aerogel precursors at 600° C. and 1,050° C., thereby carbonizing the dried carbon aerogel precursors.

(48) After measuring SEM photographs of the carbon aerogels prepared by performing the heat treatment process, the measurement results are illustrated in FIG. 5 and FIG. 6.

(49) As shown in FIG. 5 and FIG. 6, it can be seen that particles coated on the nanonetwork surface of the carbon aerogels after performing the heat treatment process differently from before performing the heat treatment process are observed.

<Experimental Example> Binding Energy Analysis

(50) After measuring binding energies of carbonized carbon aerogels prepared in the carbonization process, measurement results are illustrated in FIG. 7.

(51) It can be seen from FIG. 7 that peaks due to C—N and N═O bonds are additionally observed after the carbonization process rather than before the carbonization process, and carbon nanomaterials in which C—O bonds are decreased, and which are instead composed of C═C and C—N bonds are formed.

(52) Therefore, it is determined that oxygen functional groups included in an existing gelatin are removed through the carbonization process, and the gelatin is converted into a carbon material which is composed of C═C and C—N bonds.

(53) A carbon aerogel according to the present invention is doped with nitrogen, and a nitrogen doping ratio of the carbon aerogel is 0.001 to 0.1 of an atomic ratio of nitrogen to the carbon atom.

<Experimental Example> Specific Surface Area Analysis

(54) After measuring specific surface areas of carbonized carbon aerogels prepared in the carbonization process, the measurement results are illustrated in FIG. 8.

(55) A conventionally known pristine nanotube aerogel exhibits a specific surface area of about 1,280 m.sup.2/g, and a commercially available carbon aerogel exhibits a specific surface area of about 500 to 800 m.sup.2/g.

(56) As shown in FIG. 8, it can be seen that specific surface areas of the carbon aerogels have been greatly increased as much as not less than 2 to 3 times of surface area of a conventional carbon aerogel as the carbon aerogels prepared by embodiments of the present invention have a specific surface area of 2,572.5 m.sup.2/g.

<Experimental Example> Pore Size Distribution Analysis

(57) After measuring pore size distributions of carbonized carbon aerogels prepared in the carbonization process, the measurement results are illustrated in FIG. 9.

(58) FIG. 9 is a graph illustrating the measurement results after measuring pore channel size distributions by a mercury porosity device. In the present experiment, Autosorb IQ equipment manufactured by Quantachrome Corporation was used as surface area and pore analyzing equipment, and the analysis process was performed using nitrogen gas. Surface areas were calculated through the Brunauer-Emmett-Teller (BET) method, and pore size distributions were derived through the NL-DFT method.

(59) In FIG. 9, an X-axis indicates radius of pores. Referring to FIG. 9, it can be confirmed that sizes of pore channels in all samples of the carbonized carbon aerogels prepared in the carbonization process show bimodal distributions composed of peaks indicated by micropores of 2 nm or less and peaks indicated by mesopores of 2 nm or more.

(60) More specifically, a maximum peak of micropores is present in a range of 0.2 to 2 nm, and a maximum peak of macropores is present in a range of 2 to 40 nm.

(61) [Preparation 2 of Carbon Aerogel Precursors and Carbon Aerogels]

<Preparation Example> Preparation of Carbon Material Dispersions

(62) After adding sodium dodecylbenzene sulfonate (SDBS) as a dispersant to distilled water as a dispersion medium to obtain a mixed solution, the carbon nanotube was uniformly dispersed in the mixed solution by mixing a carbon nanotube with the mixed solution at a ratio of 0.5 wt %.

(63) After applying ultrasonic waves to a mixed solution of the carbon nanotube and a solvent and dispersing the carbon nanotube in the solvent for 2 hours to obtain a carbon material dispersion, a centrifugation process of the carbon material dispersion was performed to separate a supernatant from the carbon material dispersion. A carbon nanotube dispersion was prepared by evaporating the solvent from the separated supernatant, thereby adjusting concentration of the carbon material dispersion to 1.0 wt %.

(64) Preparation of Carbon Aerogel Precursors

(65) After mixing 3 mg of gelatin with 1 ml of distilled water, a gelatin solution was prepared by stirring the gelatin in the water until the gelatin was fully dissolved in the water at about 50° C.

(66) Subsequently, gelated carbon aerogel precursors were prepared by mixing 200 parts by weight of the gelatin solution as the binder and 100 parts by weight of sucrose having a concentration of 0.5 M as the carbon precursor per 100 parts by weight of the total weight of the carbon material dispersion prepared in the foregoing preparation example to obtain a mixed solution, uniformly dispersing the gelatin solution and sucrose in the carbon material dispersion while applying ultrasonic waves to the mixed solution at a temperature of 50° C., and leaving alone the gelatin solution and sucrose dispersed in the carbon material dispersion at a temperature of 10° C. for 1 hour.

(67) Removal of a Dispersant

(68) After increasing temperatures of the foregoing prepared carbon aerogel precursors to 60° C., thereby forming the carbon aerogel precursors in a liquid phase, the carbon aerogel precursors formed in the liquid phase were put into the cylindrical mold to form the carbon aerogel precursors in a cylindrical shape.

(69) After preparing ethanol solutions having concentrations of 10%, 20%, 40%, 80% and 100%, SDBS used as the dispersant in order to use the carbon material dispersion was removed by sequentially dipping the prepared gelated CNT-gelatin-sucrose mixed solutions in the ethanol solutions while replacing the ethanol solutions in order from an ethanol solution having a lowest concentration to an ethanol solution having a highest concentration once every three hours.

(70) Drying Process

(71) Carbon aerogels were prepared by drying the carbon aerogel precursors while substituting ethanol in the dispersant-removed carbon aerogel precursors with carbon dioxide through a critical point dryer (CPD) process.

(72) The CPD process was progressed in a method of drying the carbon aerogel precursors without damages to shape of the aerogels by blowing away carbon dioxide in the critical point state after substituting ethanol in the gelated carbon aerogel precursors with liquid carbon dioxide.

(73) The dried carbon aerogel precursors and SEM photographs of the carbon aerogel precursors are illustrated in FIG. 10 and FIG. 11.

(74) Carbonization Process

(75) Carbon aerogels according to embodiments of the present invention were prepared by heat-treating each of the dried carbon aerogel precursors at 600° C. and 1,050° C., thereby carbonizing the dried carbon aerogel precursors.

<Experimental Example> SEM Measurement

(76) SEM photographs of the carbon aerogels heat-treated at 1,050° C. by embodiments of the present invention are illustrated in FIG. 12.

(77) It can be seen from FIG. 12 that portions coated with carbon particles are observed between nanofibers which form a network in the carbon aerogels according to embodiments of the present invention.

<Experimental Example> TEM Measurement

(78) TEM photographs of carbon aerogels prepared by the embodiments of the present invention are illustrated in FIG. 13 and FIG. 14.

(79) As shown in FIG. 13 and FIG. 14, it can bee confirmed that carbon particles are formed on the surface of nanofibers in a carbon aerogel according to the present invention, and it can be confirmed that the carbon particles are arranged while constantly exhibiting orientation and forming a load in the nanofibers which form the carbon aerogels.

<Experimental Example> Binding Energy Analysis

(80) After measuring binding energies of the carbon aerogel prepared in an embodiment of the present invention, measurement results are illustrated in FIG. 15.

(81) As shown in FIG. 15, it can be seen that peaks due to C—N and N═O bonds are additionally observed after the carbonization process rather than before the carbonization process, and carbon nanomaterials in which C—O bonds are decreased, and which are instead composed of C═C and C—N bonds are formed.

(82) From this, it is determined that oxygen functional groups included in an existing gelatin are converted into a carbon material which is composed of C═C and C—N bonds through the carbonization process in an aerogel according to the present invention.

(83) As an aerogel according to the present invention was measured to contain 1.3 at. % of N when containing 96.32 at. % of C, a doping ratio of nitrogen to carbon in the carbon aerogel was measured to be 0.0135.

<Experimental Example> Specific Surface Area Analysis

(84) Results of measuring specific surface areas of the carbonized carbon aerogels are illustrated in FIG. 16.

(85) A conventionally known pristine nanotube aerogel exhibits a specific surface area of about 1,280 m.sup.2/g, and a commercially available carbon aerogel exhibits a specific surface area of about 500 to 800 m.sup.2/g.

(86) As shown in FIG. 16, it can be seen that specific surface areas of the carbon aerogels have been greatly increased as much as not less than 2 to 3 times of surface area of a conventional carbon aerogel as the carbon aerogels prepared by embodiments of the present invention have a specific surface area of 2,014 m.sup.2/g.

<Experimental Example> Pore Size Distribution Analysis

(87) After measuring pore size distributions of the prepared carbon aerogels, the measurement results are illustrated in FIG. 17. FIG. 17 is a graph illustrating the measurement results after measuring pore channel size distributions by a mercury porosity device.

(88) In the present experiment, Autosorb IQ equipment manufactured by Quantachrome Corporation was used as surface area and pore analyzing equipment, and the analysis process was performed using nitrogen gas. Surface areas were calculated through the Brunauer-Emmett-Teller (BET) method, and pore size distributions were derived through the NL-DFT method.

(89) In FIG. 17, an X-axis indicates radius of pores. Referring to FIG. 17, it can be confirmed that sizes of pore channels in all samples show bimodal distributions composed of peaks indicated by micropores of 2 nm or less and peaks indicated by mesopores of 2 nm or more, and most of pores are composed of the mesopores of 2 nm or more.

(90) [Production of Carbon Aerogel Graphene Composites]

(91) Preparation of Carbon Aerogel Precursors

(92) (1) Preparation of a Carbon Material Dispersion

(93) After adding sodium dodecylbenzene sulfonate (SDBS) as a dispersant to distilled water as a dispersion medium to obtain a mixed solution, the carbon nanotube was uniformly dispersed in the mixed solution by mixing a carbon nanotube with the mixed solution at a ratio of 0.1 wt %. After applying ultrasonic waves to a mixed solution of the carbon nanotube and a solvent and dispersing the carbon nanotube in the solvent for 2 hours to obtain a carbon nanotube dispersion, a centrifugation process of the carbon nanotube dispersion was performed to separate a supernatant from the carbon nanotube dispersion, and a carbon material dispersion was prepared by evaporating the solvent from the separated supernatant, thereby adjusting concentration of the dispersion to 0.8 wt %.

(94) (2) Preparation of a Gelatin Solution

(95) After mixing 3 g of gelatin with 1 ml of distilled water, a gelatin solution was prepared by stirring the gelatin in the water until the gelatin was fully dissolved in the water at about 50° C.

(96) (3) Mixing of a Carbon Material Dispersion and a Gelatin Solution

(97) After mixing 200 parts by weight of the gelatin solution as the binder and 100 parts by weight of sucrose having a concentration of 0.5 M as the carbon precursor with respect to 100 parts by weight of the total weight of the carbon material dispersion to obtain a mixed solution, gelated carbon aerogel precursors were prepared by uniformly dispersing the gelatin solution and sucrose in the carbon material dispersion while applying ultrasonic waves to the mixed solution at a temperature of 50° C., and leaving alone the gelatin solution and sucrose dispersed in the carbon material dispersion at a temperature of 10° C. for 1 hour.

(98) Preparation of Carbon Aerogel Graphene Composite Mixed Solutions

(99) After mixing a graphene oxide with the prepared carbon aerogel precursors at a weight ratio of 5:5 to obtain mixed solutions and applying ultrasonic waves to the mixed solutions, thereby dispersing the graphene oxide in the carbon aerogel precursors for 1 minute, carbon aerogel graphene composite mixed solutions were prepared by evaporating distilled water from the mixed solution.

(100) Manufacturing of Carbon Aerogel Graphene Composite Nanofibers

(101) Carbon aerogel graphene composite nanofibers were extracted from the prepared carbon aerogel graphene composite mixed solutions by wet spinning, and the extracted carbon aerogel graphene composite nanofibers were dried at room temperature.

<Experimental Example> Optical Microscope Analysis

(102) After measuring SEM photographs of the carbon aerogel graphene composite nanofibers manufactured in embodiments of the present invention, the measurement results are illustrated in FIG. 18.

(103) As shown in FIG. 18, it can be seen that the carbon aerogel graphene composite nanofibers manufactured by the present invention have a thickness of 16 to 18 μm.

<Experimental Example> Tensile Strength Measurement

(104) After measuring tensile strength values of the carbon aerogel graphene composite nanofibers manufactured in embodiments of the present invention, the measurement results are illustrated in FIG. 19.

(105) As shown in FIG. 19, it can be seen that carbon aerogel graphene composite nanofibers having a diameter of 20 μm manufactured by the present invention are excellent in mechanical strength by having a tensile strength value of 2.34 GPa.

<Experimental Example> Scanning Electron Microscopy (SEM) Analysis

(106) After performing SEM analysis of inner sections and surfaces of the carbon aerogel graphene composite nanofibers before carbonization produced by embodiments of the present invention, the analysis results are illustrated in FIG. 20 and FIG. 21.

<Experimental Example> Heat Treatment of Carbon Aerogel Graphene Composite Nanofibers

(107) The carbon aerogel graphene composite nanofibers manufactured in embodiments of the present invention were heat-treated at a temperature of 1,000° C. for 2 hours to reduce graphene oxide and carbonize the carbon aerogel graphene composite nanofibers by gelatin.

<Experimental Example> Transmission Electron Microscopy Analysis

(108) After performing SEM analysis of the heat-treated carbon aerogel graphene composite nanofibers, analysis results are illustrated in FIG. 22.

(109) As shown in FIG. 22, it can be confirmed that a carbon aerogel graphene composite nanofiber manufactured by the present invention has surface wrinkles formed in the longitudinal direction thereof, and the surface wrinkles are communicated with the inside of the carbon aerogel graphene composite nanofiber such that wrinkles are formed in the carbon aerogel graphene composite nanofiber.

(110) Further, it can be seen that SEM image shapes for the graphene become more clear since graphene oxide and gelatin that are nonconductive materials are reduced and carbonized after the heat treatment process such that the carbon aerogel graphene composite nanofiber exhibits conductivity.

<Manufacturing Example> Manufacturing of a Three-Electrode System

(111) A three-electrode system was prepared by using a silver/silver chloride electrode as a reference electrode, using a platinum electrode as a counter electrode, and using the carbon aerogel carbon nanotube composite or the heat-treated carbon aerogel graphene composite nanofiber as a working electrode. 0.2 M Na.sub.2SO.sub.4 was used as an electrolyte solution.

<Experimental Example> Charge-Discharge and Cyclic Voltammetry Test

(112) After performing a charge-discharge test in a range of 0 to 0.8 V by chronopotentiometry under a predetermined current ranging from 1 to 5 mA/cm.sup.2 in a 0.2 M Na.sub.2SO.sub.4 solution, thereby calculating charging capacity values, the calculation results are illustrated in FIG. 23 and FIG. 24.

<Manufacturing Example> Application to a Super Capacitor Electrode

(113) After dipping two strands of the carbon aerogel graphene composite nanofiber manufactured in an embodiment of the present invention in a PVA/H.sub.2SO.sub.4 mixed solution to obtain PVA/H.sub.2SO.sub.4 mixed solution-coated two strands of the carbon aerogel graphene composite nanofiber, a gel type solid electrolyte layer was formed on the surface of the nanofiber by drying the PVA/H.sub.2SO.sub.4 mixed solution-coated two strands of the carbon aerogel graphene composite nanofiber. A fiber type super capacitor was manufactured by bonding respective fibers coated with the solid electrolyte layer in a parallel form.

<Experimental Example> Charge-Discharge and Cyclic Voltammetry Test

(114) After performing a charge-discharge test in a range of 0 to 0.8 V by galvanostatic charge-discharge under a predetermined current ranging from 1 to 5 mA/cm.sup.2 in a 0.2 M sulfuric acid solution using the same super capacitor electrodes as an anode and a cathode in order to take a full cell electrode test, thereby calculating charging capacity values, the calculation results are illustrated in FIG. 25.

(115) After performing cyclic voltammetry in a range of 0 to 1 V at a scan speed of 1 to 100 mV/s, cyclic voltammetry results are illustrated in FIG. 26.

(116) A method of preparing a carbon aerogel according to the present invention is prepared by mixing the carbon material with the binder, thereby carbonizing a carbon aerogel precursor which can prepare a carbon aerogel although a carbon material of which length and diameter are not adjusted is used. Carbon particles formed on the surface of the carbon aerogel from the binder can adjust pore size distribution by greatly improving specific surface area and conductivity of a carbon aerogel prepared by the present invention and improving porosity of the carbon aerogel.

(117) A carbon aerogel graphene composite according to the present invention has improved tensile strength and electrical conductivity while characteristics of the carbon aerogel and characteristics of the graphene are being combined with each other, and a super capacitor including the carbon aerogel graphene composite according to the present invention exhibits an effect of greatly improving charge and discharge characteristics and lifetime characteristics.