KR101790084B1

KR101790084B1 - Method for manufacturing meso porous carbon materials

Info

Publication number: KR101790084B1
Application number: KR1020150168904A
Authority: KR
Inventors: 안효진; 안건형; 구본율
Original assignee: 서울과학기술대학교 산학협력단
Priority date: 2015-11-30
Filing date: 2015-11-30
Publication date: 2017-10-26
Also published as: KR20170064095A

Abstract

A method for producing a carbon-based material having mesopores is disclosed.
The method for preparing a mesoporous carbonaceous material according to the present invention comprises: electrospinning a mixture of a carbon precursor and a sacrificial polymer soluble in an etchant to form a primary nanofiber; Introducing the primary nanofibers into a container in which the etching agent is stored to form secondary nanofibers in which the sacrificial polymer on the surface of the primary nanofibers is removed by dissolution; And forming the final carbon nanofibers by carbonizing the secondary nanofibers, wherein ultrasonic waves are applied to the container in the secondary nanofiber manufacturing step so that the sacrificial polymers in the primary nanofiber are aggregated with each other And the mesopores are formed while the aggregated sacrificial polymers are removed during the carbonization.

Description

METHOD FOR MANUFACTURING MESO POROUS CARBON MATERIALS [0001]

The present invention relates to a method for producing a carbon-based material, and more particularly, to a method for producing mesoporous carbon nanofibers capable of having a large specific surface area by using ultrasonic waves in addition to etching.

Conductive carbon-based materials such as graphite, carbon nanotube (CNT), carbon nanofiber (CNF), and graphene have characteristics such as excellent electric conductivity, wide surface area, excellent thermal and chemical stability, Secondary batteries, capacitors, and the like.

Among them, carbon nanofibers are mainly manufactured by electrospinning. In the case of the electrospinning method, it is possible to produce a fiber phase having a length of about several tens of micrometers and a diameter of about 50 to 500 nm even at a low cost and a simple process, and it is also easy to form a complex with other materials such as polymers, ceramics and the like. Therefore, the electrospinning method is widely used as a method for producing carbon nanofibers, compared with methods such as chemical vapor deposition (CVD), vapor growth and the like.

On the other hand, an electrochemical capacitor for storing electrical energy in an electric double layer forming an interface between an electrode and an electrolyte can be classified into two types according to a mechanism. One is electrochemical double layer capacitors (EDLC) associated with non-inductive current processes using carbon-based materials such as activated carbon, graphene, carbon nanotubes and carbon nanofibers. And the other is a pseudo capacitor using RuO ₂ , NnO ₂ , CO ₃ O ₄ and conductive polymers (for example, polythiophene, polypyrrole and polyaniline).

Among these, electrochemical double layer capacitors have advantages such as excellent cycle stability and high capacity, but they have a limitation that they have a relatively low energy density. In order to overcome the low energy density of the electrochemical double layer capacitor, an electrode having excellent electric conductivity and a large surface area is required.

A background art related to the present invention is Korean Patent Laid-Open Publication No. 10-2011-0072222 (published on June 29, 2011), which discloses metal and metal oxide nanofibers having a hollow structure and a manufacturing method thereof .

It is an object of the present invention to provide a method for manufacturing a carbon-based material having a larger specific surface area than conventional methods for producing carbon-based materials.

According to another aspect of the present invention, there is provided a method for preparing a mesoporous carbon-based material, comprising: electrospinning a mixture of a carbon precursor and a sacrificial polymer soluble in an etchant to form a primary nanofiber; Introducing the primary nanofibers into a container in which the etching agent is stored to form secondary nanofibers in which the sacrificial polymer on the surface of the primary nanofibers is removed by dissolution; And forming the final carbon nanofibers by carbonizing the secondary nanofibers, wherein ultrasonic waves are applied to the container in the secondary nanofiber manufacturing step so that the sacrificial polymers in the primary nanofiber are aggregated with each other And the mesopores are formed while the aggregated sacrificial polymers are removed during the carbonization.

At this time, the etchant includes at least one of water, ethanol, methanol, isopropanol and acetone, the carbon precursor includes polyacrylonitrile (PAN), and the sacrificial polymer is polyvinylpyrrolidone (PVP) , Cellulose, polyimide, polybenzimidazole, poly (p-xylenetetrahydrothiophenium chloride), and polyvinyl alcohol (polyvinyl alcohol).

In this case, the carbon precursor and the sacrificial polymer are preferably contained in a weight ratio of 8: 2 to 6: 4.

Further, the secondary nanofibers may be stabilized at 150 to 300 ° C, and then carbonization may be performed.

Further, in order to improve the wettability with respect to the electrolyte or the like, a step of acid-treating the final carbon nanofibers may be further included.

According to another aspect of the present invention, there is provided a method for manufacturing a mesoporous carbon-based material, comprising: coating a mixture of a carbon precursor and a sacrificial polymer soluble in an etchant on a substrate to form a primary coating layer; ; Depositing the primary coating layer into a container in which the etchant is stored to form a secondary coating layer on the surface of the primary coating layer where the sacrificial polymer is removed by dissolution; And forming a final coating layer by carbonizing the secondary coating layer. In the forming of the secondary coating layer, ultrasonic waves are applied to the container to cause the sacrificial polymer in the primary coating layer to cohere with each other, The mesopores are formed while the aggregated sacrificial polymers are removed.

Further, in order to improve wettability, a step of acid-treating the final coating layer may be further included.

According to the present invention, a method of manufacturing carbon nanofibers using ordinary electrospinning and carbonization is applied, a sacrificial polymer soluble in an etchant together with a carbon precursor is included in the raw material, and ultrasound is applied to the sacrificial polymer So that mesopores can be formed in the carbonization process.

By this mesopores, the specific surface of the carbon nanofibers can be made larger, and the energy density of the electrochemical double layer capacitor can be increased.

This method can be applied not only to carbon nanofibers but also to other types of carbon-based materials such as carbon sheets.

FIG. 1 schematically shows a method for manufacturing a mesoporous carbon material according to an embodiment of the present invention, and more particularly, a method for manufacturing mesoporous carbon nanofibers.
FIG. 2 is a schematic view illustrating a method of manufacturing a mesoporous carbon material according to another embodiment of the present invention, and more particularly, a method of manufacturing a mesoporous carbon sheet.
FIG. 3 shows FE-SEM photographs of Examples and Comparative Examples after electrospinning, carbonization after water etching, and the like.
FIG. 4 shows TEM photographs of Examples and Comparative Examples after electrospinning, carbonization after water etching, and the like.
5 shows the results of DSC analysis performed in a temperature range of 30 to 500 ° C in a nitrogen atmosphere in order to determine the residual PVP content after water etching.
6 shows the pore volume and pore size distribution of carbon nanofibers according to Examples and Comparative Examples.
7 shows XRD patterns and bonding states of carbon nanofibers according to Examples and Comparative Examples.
FIGS. 8 and 9 show electrical characteristics of carbon nanofiber electrodes manufactured according to Examples and Comparative Examples.
10 is a SEM photograph of a carbon sheet prepared from a PAN raw material without PVP added and a PAN raw material containing PVP.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for producing a mesoporous carbon material according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 schematically shows a method for manufacturing a mesoporous carbon material according to an embodiment of the present invention, and more particularly, a method for manufacturing mesoporous carbon nanofibers.

Referring to FIG. 1, the mesoporous carbon-based material manufacturing method includes a primary nanofiber forming step (S110), a secondary nanofiber forming forming step (S120), and a final carbon nanofiber forming step (S130).

In the primary nanofiber formation step (S110), a spinning solution containing a mixture of the carbon precursor (10) and the sacrificial polymer (20) and a solvent is electrospun to form a primary nanofiber. Here, the sacrificial polymer 20 is soluble in a predetermined etching agent. In the secondary nanofiber forming step (S120) described later, the sacrificial polymer on the surface of the primary nanofiber is dissolved by the etchant, and the primary nanofiber .

The solvent contained in the spinning solution may be dimethylacetamide (DMAc), N, N-dimethylformamide (DMF), tetrahydrofuran (THF), dimethylsulfoxide (DMSO) and the like. After the electrospinning, a drying process for removing the solvent may be further included.

The etching agent used in the secondary nanofiber forming step described later may include one or more of water, ethanol, methanol, isopropanol, acetone, and the like. In this case, the carbon precursor 10 is a component which is not dissolved in the etching agent. For example, when the etchant is water, the carbon precursor 10 may be a hydrophobic polyacrylonitrile (PAN), or may be a styrene-acrylonitrile copolymer, a polyacrylonitrile-acrylic acid copolymer, Ronitril (PAN) may be used. The sacrificial polymer 20 may be a water-soluble hydrophilic polymer such as polyvinylpyrrolidone (PVP) or may be cellulose, polyimide, polybenzimidazole, poly p-xylenetetrahydrothiophenium chloride, and poly (vinyl alcohol). These polymers may be used singly or in combination of two or more.

Preferably, water is used as the etchant, polyacrylonitrile as the carbon precursor, and polyvinylpyrrolidone as the sacrificial polymer.

It is preferable that the carbon precursor and the sacrificial polymer are contained in a weight ratio of 8: 2 to 6: 4, that is, the carbon precursor content is 60 to 80 wt% and the sacrificial polymer content is 20 to 40 wt% By weight, and 30 to 40% by weight. If the content of the sacrificial polymer is less than 20% by weight, surface and internal pore formation may be insufficient. As the content of the sacrificial polymer increases, the porosity increases and thus the specific surface area of the carbonaceous material produced increases. However, when the content of the sacrificial polymer exceeds 40% by weight, the shape may become unstable due to excessive pores.

Electrospinning may be performed at a voltage condition of approximately 12-14 kV and a feeding rate of the spinning solution of approximately 0.02-0.06 mL / h, but is not limited thereto.

In the second nanofiber formation step (S120), the primary nanofibers formed by electrospinning are injected into a container in which the etching agent is stored to form secondary nanofibers in which the sacrificial polymer on the surface of the primary nanofibers is removed by dissolution. 1 corresponds to a portion where the sacrificial polymer on the surface of the primary nanofiber is removed. The dissolution of the sacrificial polymer can be performed for about 30 minutes to 3 hours. When the etchant is water, so-called water etching is performed.

At this time, in the case of the present invention, ultrasound is applied to the container in the secondary nanofiber forming step (S120). The frequency of the applied ultrasonic waves may be about 30 to 200 kHz. This allows the sacrificial polymers in the primary nanofiber to cohere to each other. Figure 22 shows the sacrificial polymers agglomerated by application of ultrasonic waves. As a result of the aggregation of the sacrificial polymer by the application of the ultrasonic waves, the mesopores 24 having a diameter of about 2 to 10 nm can be formed while the sacrificial polymers 22 aggregated during carbonization are removed. It seems that energy is transferred to the sacrificial polymer by ultrasound, and the sacrificial polymers that are energized coalesce by hydrogen bonding. This aggregation provides pore formation in the carbon nanofibers after carbonization.

After the formation of the secondary nanofibers, the drying process can be further performed at about 80 to 120 ° C.

Next, in the step of forming the final carbon nanofibers (S130), the secondary nanofibers are carbonized to form the final carbon nanofibers.

The carbonization can be performed at about 700 ° C to 1000 ° C.

At this time, the carbonization can be performed in a vacuum atmosphere or an inert gas atmosphere. In addition, the carbonization may be performed in a nitrogen-containing gas atmosphere. In the latter case, it is possible to manufacture nitrogen-doped carbon nanofibers.

On the other hand, it is possible to further stabilize the secondary nanofibers at 150 to 300 DEG C before carbonization. If the stabilization temperature is lower than 150 ° C., the stabilization of the carbon precursor may be insufficient. If the stabilization temperature is higher than 300 ° C., the thermal decomposition of the carbon precursor may proceed without further effect.

On the other hand, in order to improve the wettability of the produced mesoporous carbon nanofibers with respect to electrolytes, an acid treatment may be further performed using a nitric acid solution, a sulfuric acid solution, a hydrofluoric acid solution, or the like. By doing so, oxygen-containing functional groups such as CO, C = O, and OC = O groups can be formed on the surface of the carbon nanotubes, thereby improving wettability with respect to electrolytes and the like.

FIG. 2 is a schematic view illustrating a method of manufacturing a mesoporous carbon material according to another embodiment of the present invention, and more particularly, a method of manufacturing a mesoporous carbon sheet.

Referring to FIG. 2, the mesoporous carbon-based material manufacturing method includes a first coating layer forming step (S210), a second coating layer forming step (S220), and a final coating layer forming step (S230).

In the first coating layer formation step S210, a mixture of a carbon precursor and a sacrificial polymer soluble in an etchant is coated on a substrate such as glass, silicon oxide or the like to form a primary coating layer.

The coating can be carried out by various methods such as known spin coating, inkjet printing, offset printing and the like. The solvent in the mixture may be selected from the group consisting of dimethylacetamide (DMAc), N, N-dimethylformamide (DMF), tetrahydrofuran (THF), dimethylsulfoxide (DMSO ) And the like. And, the solvent contained in the mixture can be removed by drying after coating.

Next, in the secondary coating layer formation step (S220), the primary coating layer is put into a container containing an etchant capable of dissolving the sacrificial polymer to form a secondary coating layer in which the sacrificial polymer on the surface of the primary coating layer is removed by dissolution .

Also in this embodiment, in the secondary coating layer formation step (S220), ultrasonic waves are applied to the container so that the sacrificial polymers in the primary coating layer cohere with each other, and the sacrificial polymers aggregated in the carbonization process described later are removed, Can be formed.

Next, in the final coating layer forming step S230, the secondary coating layer is carbonized to form a final coating layer. Whereby a mesoporous carbon-based material in the form of a sheet can be produced.

The etchant may include at least one of water, ethanol, methanol, isopropanol, and acetone. In this case, the carbon precursor may comprise polyacrylonitrile (PAN) and the sacrificial polymer may be selected from the group consisting of polyvinylpyrrolidone (PVP), cellulose, polyimide, polybenzimidazole, poly (p-xylenetetrahydrothiophenium chloride), and polyvinyl alcohol (poly (vinyl alcohol)).

On the other hand, the secondary coating layer can be peeled from the substrate before carbonization.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense. The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

1. Chemicals

The chemicals used in Examples and Comparative Examples are as follows.

Polyacrylonitrile (PAN) (Mw = 150,000, Sigma-Aldrich)

Polyvinylpyrrolidone (PVP) (Mw = 1,300,000, Sigma-Aldrich)

N, N-Dimethylformamide (99.8%, Sigma-Aldrich), N, N-dimethylformamide

Nitric acid solution (70%, Sigma-Aldrich)

2. Manufacture of mesoporous carbon nanofibers

Example

PAN and PVP of 8: 2, 7: 3 and 6: 4 were added to DMF in a weight ratio and stirred for 5 hours to prepare a spinning solution. The total content of PAN and PVP in the spinning solution was 10% by weight. In electrospinning, the voltage and spinning solution feed rates were maintained at 13 kV and 0.03 mL / h. The distance between the syringe needle and the collector was about 15 cm, and the humidity was less than 10%.

Then, PVP was dissolved in de-ionized water for 30 minutes while ultrasonic waves of 42 kHz were applied in an ultrasonic bath. After drying at 80 ° C, it was stabilized at 280 ° C for 2 hours in air.

Thereafter, carbonization was performed in a nitrogen atmosphere at 800 ° C for 2 hours.

Thereafter, acid treatment was carried out in a nitric acid solution for 5 hours, followed by washing with deionized water and drying at 80 DEG C to prepare carbon nanofibers (AMCNF) according to the examples.

Comparative Example

The carbon nanofibers (ACNF) according to the comparative examples were prepared in the same manner as in Example but the sacrificial polymer was not included in the raw material.

3. Characterization

(1) A device for evaluating the properties of carbon nanofibers prepared according to Examples and Comparative Examples was FE-SEM (Hitachi S-4800), MULTI / TEM (Tecnai G2, KBSI Gwangju Center), DSC (Shimadzu DSC- 60), XRD (Rigaku D / Max 2500V) and XPS (ESCALAB250) were used.

(2) Results

FIG. 3 shows FE-SEM photographs of Examples and Comparative Examples after electrospinning, carbonization after water etching, and the like.

3 (a), 3 (e) and 3 (i) show comparative examples and FIGS. 3 (b), 3 (f) and 3 (j) show PAN and PVP in a weight ratio of 8: 2 (d), (h) and (l) show PAN and PVP in a weight ratio of 6: 4, Fig. 3 (a) to 3 (d) show after electrospinning, (e) to (h) show after water etching, and (i) to (1) show carbonization after.

Referring to Figs. 3 (a) to 3 (d), after electrospinning, all examples showed a smooth surface and a uniform surface profile. However, referring to FIGS. 3 (e) to 3 (h), it can be seen that as the content of PVP increases, the wrinkles on the surface become larger. The surface wrinkles can be seen as the result of PVP removal at the time of etching.

This surface wrinkle shows a rough surface as the PVP content increases, as can be seen from (i) to (l) of FIG. On the other hand, after carbonization, almost all of the specimens showed similar diameters of 191 to 217 nm.

In the case of (k) and (l) of FIG. 3, it can be seen that pores are exposed in the middle. The mesopores are formed by the coagulation of PVP in the nanofiber by the application of ultrasonic waves, and the coagulated PVP is removed in the carbonization process. Mesh pores can be exposed to the surface as shown in Figs. 3 (k) and 1 (l), while the adjacent ones of the aggregated PVPs are removed.

FIG. 4 shows TEM photographs of Examples and Comparative Examples after electrospinning, carbonization after water etching, and the like.

4 (a), 4 (e) and 4 (i) show a comparative example in which PVP is not included, (D), (h) and (l) show an embodiment in which PAN and PVP are in a weight ratio of 7: 3, And PVP in a weight ratio of 6: 4. 4 (a) to 4 (d) show post-electrospinning, (e) to (h) show after water etching, and (i) to (1) show carbonization after.

Referring to Figs. 3 (a) to 3 (d), after electrospinning, all examples showed a smooth surface and a uniform surface profile.

4 (f) to (h), however, after the water etching, the edge portion exhibits a brighter contrast than the central portion by PVP removal, which is a result substantially matching the SEM photograph of FIG. However, Fig. 4 (e), which is a result of not containing PVP, showed similar results as in Fig. 4 (a).

4 (j) to (l), internal mesopores are well formed after carbonization. On the other hand, in the case of (i) in FIG. 4, it can be seen that there is no significant change after carbonization. Such mesopores can provide a short path and low resistance to ions at high speed and high current density in electrochemical capacitors, thus providing high capacitance and high efficiency.

5 shows the results of DSC analysis performed in a temperature range of 30 to 500 ° C in a nitrogen atmosphere in order to determine the residual PVP content after water etching.

Referring to FIG. 5, the sample containing no PVP did not show a melting point but showed sharp exothermic peaks at 239 to 339 ° C. In addition, the pure PVP nanofibers showed a melting point at about 85 캜, and pyrolysis started at about 387 캜, and had a sharp exothermic peak near 467 캜.

On the contrary, in the examples (PAN / PVP-8: 2, PAN / PVP-7: 3 and PAN / PVP-6: 4), sharp PAN oxidation stabilization peaks were shown and PVP dehydrogenation peaks were hardly observed Which means that residual PVP is present.

In the case of PAN / PVP-6: 4 containing PAN and PVP in a weight ratio of 6: 4, the highest peak of heat flow was observed for the dehydrogenation of PVP, .

6 shows the pore volume and pore size distribution of carbon nanofibers according to Examples and Comparative Examples.

The pore volume of the carbon nanofibers was measured by measuring the N ₂ adsorption volume using a BET device. The pore size distribution was determined by BJH (Joyner-Halenda) analysis using N ₂ adsorption at 77K.

Table 1 shows the distribution of pore volume and mesopores (diameter of 2.4 nm or more) of the carbon nanofibers according to Examples and Comparative Examples.

[Table 1]

6 (a), 6 (b) and Table 1, it can be seen that the PVP-added specimens have a relatively large pore volume and a higher mesopore distribution fraction of 2.4 nm or more in diameter.

7 shows XRD patterns and bonding states of carbon nanofibers according to Examples and Comparative Examples.

Referring to Figure 7 (a), all specimens showed similar diffraction peaks. This means that the water etching does not affect the crystal structure.

7 (b), (c) and Table 2 show the bonded state before and after the acid treatment for the specimen of PAN: PVP = 6: 4.

[Table 2] (Unit:%)

Referring to Figures 7 (b), (c) and Table 2, after acid treatment, the CO group (285.5 eV), the C = O group (286.6 eV) OC = O group (288.9 eV) It can be seen that the number of groups increases.

(3) Evaluation of electrochemical characteristics

FIGS. 8 and 9 show electrical characteristics of carbon nanofiber electrodes manufactured according to Examples and Comparative Examples.

Electrochemical measurements were performed using two symmetrical electrodes. 10% by weight of Ketjenblack (Mitsubishi Chemical, ECP-600JD) as a conductive material and 10% by weight of polyvinylidene difluoride (PVDF) as a binder, (Solvent: N-methyl-2-pyrrolidinone, 99.5%) was coated on a 1 cm x 1 cm Ni foam and the resultant was dried at 100 ° C for 12 hours to prepare an electrode.

A 6M KOH solution was used as the electrolyte.

Cyclic voltammetry (CV) measurements were made using a potentiostat / galvanostat (Autolab PGSTAT302N, FRA32M) at a scan rate of 110 mV s ^-1 in a voltage range of 0.0-1.0 V.

The galvanostatic charging / discharging test was performed using a battery cycler system (Won-A Tech. WMPG3000) at a current density of 0.2 to 10 A g ^- ¹ at a voltage range of 0.0 to 1.0V.

The cycle durability of the electrodes was measured up to 3,000 cycles at a current density of 1 A g < ^{-1 &} gt ;.

Referring to FIGS. 8A to 8D and FIGS. 9A and 9B, the voltage-current characteristics, the capacitance, the energy density, the durability up to 3000 cycles And the higher the content of PVP, the greater the effect.

(4) Carbon Sheet Evaluation

10 is a SEM photograph of a carbon sheet prepared from a PAN raw material without PVP added and a PAN raw material containing PVP.

For the experiment, a coating solution containing 10 wt% of PAN and 90 wt% of N, N-dimethylformamide and 6 wt% of PAN, 4 wt% of PVP, 90 wt% of N, N-dimethylformamide % Was spin-coated at 500 rpm for 30 seconds. Thereafter, the wafer was dried at 80 DEG C, water-etched with deionized water in a state where ultrasonic waves of 42 kHz were applied from an ultrasonic bath, and then dried again at 80 DEG C. [ Thereafter, it was carbonized at 800 ° C.

10 (a), 10 (c) and 10 (e) show examples in which PVP is not added, and FIGS. 10 (b) (b) after spin coating, (c) and (d) after water etching, and (e) and (f) show the surface of the specimen after carbonization.

Referring to FIG. 10, it can be seen that the PVP-added specimen showed surface pores after water-etching compared with the pure PAN-based specimen without PVP addition, and the amount of pores resulting from carbonization was remarkably increased. PVP agglomeration occurs by ultrasonic waves, and massive meso pores are formed by carbonization.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Such changes and modifications are intended to fall within the scope of the present invention unless they depart from the scope of the present invention. Accordingly, the scope of the present invention should be determined by the following claims.

10: carbon precursor
12: part of the surface where the sacrificial polymer is removed
20: sacrificial polymer
22: Agglomerated sacrificial polymer
24: Mesoporous

Claims

Electrospinning a mixture of a carbon precursor and a sacrificial polymer soluble in an etchant to form a primary nanofiber;
Introducing the primary nanofibers into a container in which the etching agent is stored to form secondary nanofibers in which the sacrificial polymer on the surface of the primary nanofibers is removed by dissolution;
And carbonizing the secondary nanofibers to form a final carbon nanofiber,
In the second nanofiber manufacturing step, ultrasound with a frequency of 30 to 200 kHz is applied to the container to cause the sacrificial polymer in the primary nanofiber to cohere with each other, so that when the carbonized sacrificial polymer is removed, To form a mesopore of 10 nm to 10 nm.

The method according to claim 1,
The etchant includes at least one of water, ethanol, methanol, isopropanol, and acetone,
Wherein the carbon precursor comprises polyacrylonitrile (PAN)
The sacrificial polymer is selected from the group consisting of polyvinylpyrrolidone (PVP), cellulose, polyimide, polybenzimidazole, poly (p-xylenetetrahydrothiophenium chloride) and polyvinyl alcohol) Wherein the mesoporous carbon-based material is at least one selected from the group consisting of carbon nanotubes and carbon nanotubes.

3. The method of claim 2,
Wherein the carbon precursor and the sacrificial polymer are contained in a weight ratio of 8: 2 to 6: 4.

The method according to claim 1,
Wherein the secondary nanofibers are stabilized at a temperature of from 150 to 300 DEG C, and then the carbonization is performed.

The method according to claim 1,
And then acid-treating the final carbon nanofibers. &Lt; RTI ID = 0.0 > 8. < / RTI >

Coating a mixture of a carbon precursor and a sacrificial polymer soluble in an etchant on a substrate to form a primary coating layer;
Depositing the primary coating layer into a container in which the etchant is stored to form a secondary coating layer on the surface of the primary coating layer where the sacrificial polymer is removed by dissolution;
And carbonizing the secondary coating layer to form a final coating layer,
In the secondary coating layer forming step, ultrasound with a frequency of 30 to 200 kHz is applied to the container to cause the sacrificial polymer in the primary coating layer to cohere with each other, so that when the sacrificial polymer is removed during the carbonization, Wherein the mesopores of the mesoporous carbon material are formed to have a thickness of 10 nm.

The method according to claim 6,
The etchant includes at least one of water, ethanol, methanol, isopropanol, and acetone,
Wherein the carbon precursor comprises polyacrylonitrile (PAN)
The sacrificial polymer is selected from the group consisting of polyvinylpyrrolidone (PVP), cellulose, polyimide, polybenzimidazole, poly (p-xylenetetrahydrothiophenium chloride) and polyvinyl alcohol) Wherein the mesoporous carbon-based material is at least one selected from the group consisting of carbon nanotubes and carbon nanotubes.

8. The method of claim 7,
Wherein the carbon precursor and the sacrificial polymer are contained in a weight ratio of 8: 2 to 6: 4.

The method according to claim 6,
Further comprising the step of acid treating the final coating layer.