KR101438065B1

KR101438065B1 - Hybrid nano-complex, method for producing the same, and electrode for supercapacitor comprising the same

Info

Publication number: KR101438065B1
Application number: KR20120146083A
Authority: KR
Inventors: 윤현석; 양갑승; 김태준
Original assignee: 전남대학교산학협력단
Priority date: 2012-12-14
Filing date: 2012-12-14
Publication date: 2014-09-15
Also published as: KR20140083070A

Abstract

More particularly, the present invention relates to a hybrid nanocomposite having properties suitable for use as a material for a high-energy storage device, a method for producing the composite, and a super- And an electrode for a capacitor.

Description

[0001] The present invention relates to a hybrid nanocomposite, a hybrid nanocomposite, a method for producing the composite, and an electrode for a supercapacitor including the hybrid nanocomposite (method for producing the same and an electrode for a supercapacitor)

Recent developments of carbon-based materials are widely used in many fields, especially in energy storage systems using the electric double layer principle. Particularly, the carbon nanofibers have a uniform pore distribution as compared with activated carbon, and can be manufactured with high specific surface area and high specific surface area, felted shape, and negative shape, thereby providing a high performance electrode active material. The electrical double layer capacitor (EDLC) using the carbon nanofibers utilizes the fact that ions of the electrolyte solution are physically absorbed and desorbed while forming an electrical double layer on the electrode surface, and carbon nanofibers Exhibits excellent power density due to uniform surface pores and high non-marking strength.

However, since charge accumulation occurs only on the surface electric double layer, there is a disadvantage in that the energy density is low due to the low capacitance. Therefore, pseudocapacitance is used as a method to reinforce this. The pseudo-capacitance is the accumulation mechanism in which protons move due to the oxidation reaction of metal oxides. Therefore, since the non-accumulation capacity is higher than that of the electric double layer, It reinforces density. The metal oxide-based electrode materials for pseudo-capacitors reported so far include RuO

, IrO

, NiO

, CoO

, MnO

And the like.

Among them, manganese oxide (MnO

) Have been studied extensively, but there has been a problem in that a low yield and a long synthesis time are required, and there is a problem that they have a low non-storage capacity and a large resistance similar to other metal oxide electrode materials.

In order to reinforce these disadvantages, it is necessary to increase the surface of the reactive species and reduce the reaction rate by increasing the porosity of the electrode material, improving the output of the electrons, and increasing the size.

In particular, the synthesis of manganese oxide-carbon nanocomposite materials has been disclosed in Korean Patent Application No. 10-2004-0090286, which discloses not only coating a uniform metal oxide on a carbon material, There is a problem in that the amount of control can not be controlled. In order to solve these problems, Korean Patent Laid-Open No. 10-2011-0033733 discloses a method of manufacturing a carbon nanofiber having a microfine fiber web by electrospinning and coating a manganese oxide by a chemical method, Of course, a high-performance hybrid capacitor electrode having a high electrode density and a high energy density due to an electric double layer and a pseudo-capacitance has been disclosed. However, despite these studies, super capacitors still show performance limitations, so much effort is being made to improve the performance of supercapacitors.

As a result of efforts to solve the above problems, the present inventors have completed the present invention by developing a novel hybrid nanocomposite in which carbon nanofibers are arranged between graphene sheets.

Accordingly, it is an object of the present invention to provide a graphene sheet which can exhibit optimum performance of one graphene sheet which is easily adhered to each other through the interaction of? -N via an insertion structure in which carbon nanofibers are arranged between graphen sheets, The present invention also provides a hybrid nanocomposite having a novel structure in which carbon nanofibers disposed between sheets are inserted between graphene sheets to improve performance characteristics, a method for producing the composite, and an electrode for a supercapacitor including the hybrid nanocomposite.

It is another object of the present invention to provide a composite material which can exhibit a composite function of a pseudo capacitor and a double layer capacitor through an insertion structure in which carbon nanofibers are disposed between graphen sheets, A hybrid nanocomposite having both a high density and a high power density, a method for producing the composite, and an electrode for a supercapacitor including the hybrid nanocomposite.

Another object of the present invention is to provide a hybrid nanocomposite having at least one of physical, chemical and electrical properties of the hybrid nanocomposite by controlling the content of the graphene sheet and the carbon nanofiber, A hybrid nanocomposite, a method for producing the composite, and an electrode for a supercapacitor including the hybrid nanocomposite.

It is a further object of the present invention to provide a method of manufacturing a nanofiber composite material which includes at least one insertion structure in which carbon nanofibers are disposed between graphen sheets, And a hybrid nanocomposite material.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to achieve the above-mentioned object of the present invention, the present invention provides a hybrid nanocomposite comprising at least one insertion structure in which carbon nanofibers are arranged between graphene sheets.

In a preferred embodiment, the graphene sheet comprises reduced graphene oxide.

In a preferred embodiment, the carbon nanofibers include a metal oxide.

In a preferred embodiment, the metal oxide is any one of manganese oxide, ruthenium oxide, iridium oxide, cobalt oxide, and nickel oxide.

In a preferred embodiment, the metal oxide is coated on the surface of the carbon nanofibers.

In a preferred embodiment, the metal oxide contained in the carbon nanofibers is 10 to 60 wt%.

In a preferred embodiment, the carbon nanofibers have a diameter of 1 to 500 nm.

In a preferred embodiment, it comprises 10 to 60% by weight of the graphene sheet and 40 to 90% by weight of the carbon nanofibers.

The present invention also provides a method of manufacturing a carbon nanofiber, Preparing a graphene oxide dispersion; And adding the carbon nanofibers to the graphene oxide dispersion to form an insertion structure in which carbon nanofibers are disposed between graphene sheets composed of graphene oxide.

In a preferred embodiment, the method further comprises reducing the graphene sheet constituting the insert structure.

In a preferred embodiment, the step of forming the insert structure is performed by uniformly dispersing the carbon nanofibers added to the graphene oxide dispersion.

In a preferred embodiment, the reducing step is carried out by adding a reducing agent to the reactor in which the step of forming the insert structure has been performed and stirring.

In a preferred embodiment, the reducing agent is any one of a hydrazine solution and a sodium borohydride (NaBH ₄ ) solution.

In a preferred embodiment, the reducing step includes a step of heat-treating the graphene sheet constituting the insert structure at 200 to 2000 ° C.

In a preferred embodiment, the step of preparing the carbon nanofibers includes preparing a spinning solution containing a carbon fiber precursor material and a metal oxide; Preparing a precursor fiber containing metal oxide by electrospinning the spinning solution; Oxidizing and stabilizing the precursor fibers to produce metal chloride-containing chlorinated fibers; And carbonizing the chlorinated fibers.

In a preferred embodiment, the prepared spinning solution further comprises a film former.

In a preferred embodiment, the film-forming agent is selected from the group consisting of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyacrylate, polyacrylic acid, and soluble starch It is one.

In a preferred embodiment, the carbon fiber precursor material is selected from the group consisting of polyacrylonitrile (PAN), polyacrylonitrile copolymer, polyvinyl alcohol (PVA), polyimide (PI), polybenzyl (PBI), phenol resin, epoxy resin, polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polystyrene , polystyrene, polyanaline, polymethylmethacrylate (PMMA), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), and various pitches. . &Lt; / RTI >

In a preferred embodiment, the carbonization process is carried out at 800 DEG C to 1000 DEG C under a stream of nitrogen.

In a preferred embodiment, the content of the carbon nanofibers and graphene oxide is controlled to control one or more of the physical, electrical, and chemical properties of the hybrid nanocomposite.

The present invention also provides an electrode for a supercapacitor comprising any one of the hybrid nanocomposites described above or a hybrid nanocomposite prepared by any one of the methods.

In a preferred embodiment, the electrode comprises H

SO

And a capacity of 174 F / g when it is an aqueous 1M electrolyte solution.

The present invention has the following excellent effects.

First, according to the present invention, not only is it possible to exhibit the optimum performance of one graphene sheet which is easily attached to each other through the interaction of? -? Via the insertion structure in which carbon nanofibers are arranged between graphen sheets, The carbon nanofibers disposed between the graphene sheets are also inserted between the graphene sheets to improve the performance characteristics.

According to the present invention, a composite function of a pseudo capacitor and a double-layer capacitor can be exhibited through an insertion structure in which carbon nanofibers are disposed between graphen sheets, so that energy suitable for application as a material for a high- Density and high power density.

According to the present invention, since the carbon nanofibers are interposed between the graphen sheets, the content of the graphene sheet and the carbon nanofibers can be controlled to control at least one of the physical, chemical and electrical properties of the hybrid nanocomposite can do.

Further, according to the present invention, by including at least one insertion structure in which carbon nanofibers are disposed between graphen sheets, it is possible to produce new nanoparticle materials having physical, chemical and electrical properties different from those of conventional graphene sheets or carbon nanofibers In hybrid nanocomposite can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flow chart schematically showing a method for producing a hybrid nanocomposite (manganese oxide / carbon nanofibers / graphene sheet) according to embodiments of the present invention;
FIG. 2 is a photograph showing a) PVP / PAN mixed image and b) PVP / PAN mixed with manganese ion,
3 is a transmission electron microscope (TEM) photograph of a) manganese oxide / carbon nanofiber in the hybrid nanocomposite obtained in the embodiment of the present invention; b) a TEM photograph showing an enlarged view of manganese oxide / carbon nanofiber; C) a hybrid nanocomposite Oxide / carbon nanofiber / reduced graphene sheet) was observed with a scanning electron microscope (SEM)
FIG. 4 is a photograph of the material of each of the hybrid nanocomposites obtained in the embodiments of the present invention a) X-ray photoelectron spectroscopy (XPS) b) C 1 S enlargement of XPS c) Manganese oxide / carbon nanofibers / Mn 2p graph of sheet (MCNF / RGO)
FIG. 5 is a graph showing a CV measurement result of a hybrid nanocomposite obtained in the embodiments of the present invention using a three-electrode cell, wherein a) shows the RGO content of manganese oxide / carbon nanofibers / (B) is a cyclic voltammetry graph according to the content of GO in the manganese oxide / carbon nanofibers / reduced graphene sheet, and (c) is a cyclic voltammetry graph A graph in which a cyclic voltammetry is calculated,
FIG. 6 is a graph showing the results of a constant current charge-discharge test performed on the hybrid nanocomposites obtained in the examples of the present invention, wherein a) and b) show the charge / discharge (galvanostatic charge / discharge) Graph c) is the IR drop calculation graph in a) and b), d) and e) is the capacitance graph calculated through graphs a) and b), f) shows the long-term cycling performances according to the difference in RGO / GO .

Although the terms used in the present invention have been selected as general terms that are widely used at present, there are some terms selected arbitrarily by the applicant in a specific case. In this case, the meaning described or used in the detailed description part of the invention The meaning must be grasped.

As used herein, the term "graphene sheet" includes all graphene sheets consisting of one to several hundreds of layers, unless otherwise specified, and includes graphene oxide [GO (graphene oxide)], reduced graphene oxide [ RGO (reduced graphene oxide)].

Hereinafter, the technical structure of the present invention will be described in detail with reference to the accompanying drawings and preferred embodiments.

However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Like reference numerals used to describe the present invention throughout the specification denote like elements.

The first technical feature of the present invention resides in that carbon nanofibers are disposed between graphene sheets which are easily attached to each other by the interaction of? - ?, thereby forming an insertion structure in which carbon nanofibers are inserted between graphen sheets, In addition to being able to achieve one optimum performance, carbon nanofibers are also inserted between graphene sheets to improve performance characteristics, so that hybrid components are able to exhibit synergistic effects with each other.

As a result, the hybrid composite of the present invention has different physical, chemical and electrical characteristics as compared with conventional graphene sheets, carbon nanofibers, and carbon nanofiber composites. Especially, the hybrid composite has a complex function of a pseudo capacitor and a double layer capacitor It is possible to realize energy densities and high power densities suitable for application as materials for high capacity energy storage devices.

Accordingly, the present invention provides a hybrid nanocomposite comprising at least one insertion structure in which carbon nanofibers are disposed between graphene sheets.

The graphene sheet included in the hybrid nanocomposite of the present invention may be composed of at least one of graphene oxide (GO) and reduced graphene oxide (RGO) It is preferable that it is made of only reduced graphene oxide.

In the present invention, the graphene sheet means a graphene sheet consisting of one to several hundreds of layers, preferably a graphene sheet of less than a hundred layers, and more preferably a graphene sheet of less than fifty layers.

The carbon nanofibers included in the hybrid nanocomposite of the present invention are not limited as long as they are carbon nanofibers, but carbon nanofibers containing metal oxides are preferable. In this case, the metal oxide may be any one of manganese oxide, ruthenium oxide, iridium oxide, cobalt oxide, and nickel oxide. The metal oxide contained in the carbon nanofibers may be coated on the surface of the carbon nanofibers. The metal oxide contained in the carbon nanofibers may be 5 to 60% by weight. If the amount is less than 5% by weight, the performance is not improved. If the amount exceeds 60% by weight, the mechanical properties of the carbon nanofibers are deteriorated to be.

In addition, the carbon nanofibers included in the hybrid composite of the present invention may have a diameter of several hundred nanometers, but it is preferably 1 to 500 nm, and in particular, when the nanocomposite is to be formed, the diameter of the carbon nanofiber is preferably 100 nm or less.

Meanwhile, the hybrid nanocomposite of the present invention can control physical, chemical and electrical properties according to the content of the graphene sheet and the carbon nanofibers. When the hybrid nanocomposite is used as a high energy storage material, % Of the carbon nanofibers and 40 to 90 wt% of the carbon nanofibers. This is because graphene and carbon fiber in this range reduce contact resistance through good interfacial contact and smooth the movement of the electrolyte by forming an open structure.

A second technical feature of the present invention resides in a method for manufacturing a hybrid composite of a new structure by forming an inserted structure in which carbon nanofibers are inserted between graphene sheets through a very simple and environmentally friendly manufacturing process.

Accordingly, the present invention provides a method for producing carbon nanofibers, comprising: preparing carbon nanofibers; Preparing a graphene oxide dispersion; And adding the carbon nanofibers to the graphene oxide dispersion to form an insertion structure in which carbon nanofibers are disposed between graphene sheets composed of graphene oxide (refer to Fig. 1 Reference). And optionally reducing the graphene sheet constituting the inserted structure.

First, the step of producing the carbon nanofibers may be performed according to a known carbon nanofiber manufacturing process, but the metal oxide-containing carbon nanofibers shown in FIG. 1 may be prepared by preparing a spinning solution containing a carbon fiber precursor material and a metal oxide Process; Preparing a precursor fiber containing metal oxide by electrospinning the spinning solution; Oxidizing and stabilizing the precursor fibers to produce metal chloride-containing chlorinated fibers; And a step of carbonizing the chlorinated fibers. It is more preferable that the carbonizing step is carried out at 600 to 1200 ° C in a nitrogen stream. If the spinning solution does not contain a metal oxide, the carbonization process may be carried out at 600 ° C to 2000 ° C under a nitrogen stream.

In particular, if a coating agent is further included in the spinning solution, the metal oxide can be induced to be coated on the surface of the carbon nanofibers. Here, the film-forming agent may be any one of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyacrylate, polyacrylic acid, and soluble starch, 0.01 to 60% by weight based on the spinning solution.

The carbon fiber precursor material for producing the carbon nanofibers of the present invention may be selected from the group consisting of polyacrylonitrile (PAN), polyacrylonitrile copolymer, polyvinyl alcohol (PVA), polyimide (PI) , Polybenzimidazole (PBI), phenol resin, epoxy resin, polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) (PS), polystyrene, polyanaline (PA), polymethylmethacrylate (PMMA), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF) (pitch).

Next, the step of preparing the graphene oxide dispersion can be obtained by forming a graphene oxide (GO) from a graphite powder using a Hummers and Offeman method, followed by water dispersion.

Next, the step of forming the insert structure can be performed by uniformly dispersing the carbon nanofibers added in a certain amount in the graphene oxide dispersion. By controlling the content of the carbon nanofibers and the graphene oxide, the physical properties of the hybrid nanocomposite , Chemical, and electrical properties, so that content control can be made depending on the application. Any known method may be used for the dispersion method, but in the embodiment of the present invention described below, ultrasonic dispersion is performed, followed by stirring in an agitator.

In other words, a graphene sheet made of graphene oxide [GO sheet] is very well dispersed in an aqueous solution and is very similar to a CNF-like structure. Therefore, since the GO sheet acts as an amphipathic substance, CNF can be dispersed in an aqueous solution, and CNF / GO hybrid composites with CNF inserted between the GO sheets can be easily formed through dispersion.

Next, the reducing step is carried out by adding a reducing agent to the reactor in which the step of forming the inserted structure is performed, followed by stirring. Any of hydrazine solution and sodium borohydride (NaBH ₄ ) may be used as the reducing agent. In other words, CNF / RGO hybrid complexes can be easily prepared by converting GO to RGO using a reducing agent such as hydrazine after the CNF / GO hybrid complex is formed.

Also, the reducing step may be performed by heat-treating the CNF / GO hybrid composite at 200 to 2000 ° C. That is, since the CNF / GO hybrid complex formed after the step of forming the insert structure is filtered, dried, and then subjected to a heat treatment, a CNF / RGO hybrid composite can be obtained.

The CNF / GO hybrid composite and the CNF / RGO hybrid composite structure described above have various advantages such as 1) electrical contact between the CNFs improved and 2) prevention of the accumulation of graphene sheets in the manufacturing process.

Specifically, graphene has high surface area and high conductivity (RGO film: ca 1740 S cm

), But the graphene sheet can not exhibit one optimum performance of the graphene sheet in the electrochemical reaction because it easily attaches to each other due to the interaction of? However, if the CNF / GO or CNF / RGO hybrid composite structure is provided, it is possible to prevent the accumulation of GO or RGO in the reaction solution due to CNF.

According to the manufacturing method of the present invention, it is possible to produce a hybrid composite material as simple as several tens of grams.

The hybrid nanocomposite of the present invention as described above can exhibit a composite function of a pseudo capacitor and a double layer capacitor through an insertion structure in which carbon nanofibers are disposed between graphen sheets, It can be used as a high energy electrode material such as a super capacitor because it has an energy density and a high power density suited for application. In particular, the electrode for a supercapacitor comprising the hybrid nanocomposite of the present invention is characterized in that H

SO

And a capacity of 174 F / g when it is an aqueous 1M electrolyte solution.

In addition, the hybrid nanocomposite of the present invention not only exhibits the optimum performance of a graphene sheet that is easily adhered to each other due to the interaction of π-π as well as a high energy electrode material, Since the fibers are also inserted between the graphene sheets, the performance characteristics are improved, so that they can be applied to various carbon nanofiber applications including catalyst supports, high strength stiffeners, and high strength filters.

Example 1

1. Manufacture of manganese oxide / carbon nanofibers containing manganese oxide

To prepare carbon nanofibers containing manganese oxide, 0.2 g of PAN (molecular weight = 15,000) was prepared by dissolving in 20 mL of dimethylformamide (DMF) at 80 ° C for 1 hour. In addition, manganese acetate (Mn (ace)

) And 2 g of polyvinylpyrrolidone PVP as a film-forming agent were dissolved in 40 mL of DMF and dissolved at 50 ° C for 2 hours to prepare a solution. The prepared two solutions were mixed and mixed at 80 to 90 ° C for 3 hours to prepare a spinning solution. This spinning solution was spinned at a rate of 5 ㎕ / min and a voltage of 13 kV with a single-nozzle of 1 mm to obtain manganese oxide-containing precursor fibers.

The precursor fibers obtained by electrospinning were oxidized and stabilized for 2 hours at 400 ° C in an air stream to obtain manganese oxide containing chlorinated fibers.

Carbon nanofibers (MCNFs) containing manganese oxide were prepared by carbonizing the oxidized and stabilized chlorinated fibers while maintaining them in a nitrogen gas stream for 1 hour.

2. Preparation of graphene oxide dispersion

First, graphene oxide (GO) was obtained using graphite powder by Hummers and Offeman method. An aqueous dispersion in which 15 wt% of GO was dispersed was prepared.

3. Manufacture of hybrid composites containing manganese oxide, carbon nanofiber and graphene sheet

0.5 g of MCNFs was added to the water dispersion prepared by dispersing 15 wt% of the GO prepared and mixed. The mixed solution was dispersed for 10 minutes using an ultrasonic disperser (sonicator), followed by stirring at 30 ° C for 1 hour. The resulting MCNF / GO was filtered with water and dried in a vacuum oven at 25 ° C. to prepare MCNF / GO (15 wt%).

Example 2

The MCNF / GO was formed by stirring in Example 1, and then 5 μl of 35% hydrazine solution was added to the MCNF / GO (15% by weight) contained in the reactor without filtration and drying, and the mixture was stirred at 95 ° C for 1 hour, MCNF / RGO (15 wt%) was prepared in the same manner as in Example 1, except that the step of reduction with reduced graphene oxide (RGO) was further performed.

Example 3

MCNF / GO (30 wt%) was prepared in the same manner as in Example 1, except that an aqueous dispersion in which GO was dispersed in 30 wt% was used as the graphene oxide dispersion.

Example 4

MCNF / RGO (30% by weight) was prepared in the same manner as in Example 2, except that an aqueous dispersion in which GO was dispersed in 30% by weight was used as the graphene oxide dispersion.

Example 5

MCNF / GO (50 wt%) was prepared in the same manner as in Example 1, except that an aqueous dispersion in which GO was dispersed in 50 wt% was used as the graphene oxide dispersion.

Example 6

MCNF / RGO (50% by weight) was prepared in the same manner as in Example 2, except that an aqueous dispersion in which GO was dispersed in 50% by weight was used as the graphene oxide dispersion.

Experimental Example 1

The characteristics of carbon nanofibers (MCNFs) containing manganese oxide were analyzed as follows, and the results of the analysis were described with reference to FIG.

In order to prepare MCNFs in Example 1, PAN, PVP, Mn (Ac)

Is initially dispersed in DMF, phase separation occurs between the two polymers. This is because the solubility parameters of PVP, PAN, and DMF are 25.6, 25.3-26.1 and 24.8 MPa

. Therefore, PAN and PVP can theoretically be completely dissolved in DMF. However, the lactam group in PVP can form a resonance structure with manganese ions, which can be seen in the figure below.

Due to the resonance structure with the manganese ion of PVP, phase separation occurs between PVP and PAN. Referring to FIG. 2, it can be seen that before and after putting manganese ions in PVP / PAN mixed solution. Figure 2 a) PVP / PAN mixed solution shows only a slightly metastable appearance. However, b) of Figure 2 with manganese ions shows perfect phase separation. When the polymer separated by phase separation is electrospun with a single nozzle, a fiber form coated with manganese ion / PVP on the PAN nanofiber is obtained. When the nanofibers thus obtained are calcined at 400 ° C, they are stabilized by carbonization of PAN and manganese ions become manganese oxides. Thereafter, MCNFs are obtained by carbonizing at 900 ° C in a nitrogen stream for 1 hour.

Experimental Example 2

The MCNF / RGO (50 wt%) obtained in Example 6 was analyzed by TEM and SEM, and the results are shown in Fig.

The image of MCNF can be seen in FIG. 3 a), and the diameter of MCNF is 48 ± 6 nm. The diameter of the nanometer-sized manganese oxide is 15 ± 5 nm in diameter and dispersed in CNF, which can be seen in FIG. 3 b. And thermogravimetric analysis (TGA) analysis showed that MCNF contained about 55 wt% of manganese. FIG. 3c is a photograph of a side view of the MCNF / RGO nanohybrid (RGO 50 wt%) placed on silicon and observed by a SEM. The SEM image shows nanofibers and graphene sheets, It can be confirmed that an insertion structure existing between the pin sheets is formed.

Experimental Example 3

pristine CNF, MCNF, MCNF / GO (15 wt%) obtained in Example 1 and MCNF / RGO (15 wt%) obtained in Example 2 were analyzed by XPS and the results are shown in Fig.

Referring to FIG. 4 a, all XPS spectra (0-1200 eV) of four different samples are shown, showing that the spectrum consists only of carbon, oxygen, and manganese without any other impurities. In particular, from FIG. 4 (b) to (iii), GO

It was confirmed that the carbon peak was reduced to RGO and disappeared. 4 (c) shows the Mn 2p spectrum, and Mn 2p

And 2p

Were respectively 642 and 653 eV (11 eV difference), and MnO

Respectively.

Experimental Example 4

In order to observe the electrochemical characteristics of the MCNF / RGO hybrid composite, the hybrid complexes obtained in Examples 1 to 6 were subjected to CV measurement using a three-electrode cell and the results are shown in FIG. In this case, a polymer binder (1 wt% PVDF) was used for the preparation of the electrodes, a scanning speed of 25 mV / s, a voltage range of -0.5 to 1 V and an electrolyte solution of 1 mol of sulfuric acid. The Pt electrode was used as the counter electrode, and the Ag / AgCl electrode was used as the reference electrode.

The graph of FIG. 5 shows that the performance of the RGO is higher than that of the GO, and the RGO content of the RGO is 50 wt%, respectively.

Experimental Example 5

The hybrid capacitors obtained in Examples 1 to 6 were subjected to a constant current charge-discharge test to measure the detailed non-storage capacity of the samples. The results can be seen from FIG. The voltage range of the charge-discharge experiment can be selected through the voltage range of the CV graph. All graph curves show that the charge-discharge was done to the voltage range. However, the discharge curves of the charge-discharge graph are not perfectly connected because the discharge curves of the electronic double-layer capacitance and the Faraday capacitance result in a slight first discharge in the electron double-layer capacitance.

6 (a)), it was confirmed that the discharge time was increased by increasing the RGO content of MCNF / RGO and it was confirmed that the discharge time was 174 F / g which is the highest when the RGO content was 50 wt%. It can be seen that the performance is much improved as compared with the pure RGO capacity of 40 F / g.

Conversely, the higher the content of GO, the smaller the capacity, and the result is the same as the CV graph.

As shown in FIG. 6 c), MCNF / RGO and MCNF / GO iR drop are decreased when the content of RGO is increased and increased when the content of GO is increased there was.

These experimental results show that the RGO sheet allows hybrid composites to have good conductivity and better performance with electron double layer capacitance electrode materials.

Finally, as shown in FIG. 6 (f), the long-term stability of the MCNF / RGO hybrid and the MCNF / GO hybrid was confirmed. In the case of the MCNF / RGO hybrid, the performance was reduced by about 8% While the MCNF / GO hybrid showed about 40% performance degradation and no more than 300 tests. All of the above results show that the MCNF / RGO hybrid composites show better performance than the MCNF / GO hybrid composites in terms of electrical properties.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, Various changes and modifications will be possible.

Claims

delete

Producing carbon nanofibers;
Preparing a graphene oxide dispersion;
Adding the carbon nanofibers to the graphene oxide dispersion to form an insertion structure in which carbon nanofibers are disposed between graphene sheets composed of graphene oxide; And
And reducing the graphene sheet constituting the inserted structure,
Wherein the step of forming the insert structure is performed by uniformly dispersing the carbon nanofibers added to the graphene oxide dispersion.

delete

10. The method of claim 9,
Wherein the step of reducing is performed by adding a reducing agent to the reactor in which the step of forming the inserted structure is performed and stirring the resultant.

13. The method of claim 12,
Wherein the reducing agent is any one of a hydrazine solution and sodium borohydride (NaBH ₄ ).

10. The method of claim 9,
Wherein the reducing step comprises heat treating the graphene sheet constituting the insert structure at 200 to 2000 ° C.

The method according to claim 9, wherein the step of producing the carbon nanofibers
Preparing a spinning solution containing a carbon fiber precursor material and a metal oxide;
Preparing a precursor fiber containing metal oxide by electrospinning the spinning solution;
Oxidizing and stabilizing the precursor fibers to produce metal chloride-containing chlorinated fibers; And
And carbonizing the chlorinated fibers. The method for producing a hybrid nanocomposite according to claim 1,

16. The method of claim 15,
Wherein the prepared spinning solution further comprises a film-forming agent.

17. The method of claim 16,
Wherein the film-forming agent is any one of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyacrylate, polyacrylic acid, and soluble starch Hybrid nanocomposite.

16. The method of claim 15,
The carbon fiber precursor material may be selected from the group consisting of polyacrylonitrile (PAN), polyacrylonitrile copolymer, polyvinyl alcohol (PVA), polyimide (PI), polybenzimidazole (PBI) polybenzimidazole, phenol resin, epoxy resin, polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polystyrene (PS), polystyrene PA, polyanaline, polymethylmethacrylate (PMMA), polyvinylidene chloride (PVDC), polyvinylidene fluoride (PVDF), and various pitches. Wherein the hybrid nanocomposite is produced by a method comprising the steps of:

16. The method of claim 15,
Wherein the carbonization is performed at a temperature of 600 ° C to 1200 ° C under a nitrogen stream.

10. The method of claim 9,
And controlling at least one of physical, electrical, and chemical properties of the hybrid nanocomposite by controlling the content of the carbon nanofibers and the graphene oxide.

An electrode for a supercapacitor, comprising a hybrid nanocomposite produced by the method of any one of claims 9, 12 and 20.