KR101126784B1 - Method for producing complex of Manganese dioxide and carbon nanofiber and pseudo capacitor including the complex - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid capacitor electrode for simultaneously obtaining a high energy density and a high power density by performing a complex function of a high capacity pseudo capacitor and a double layer capacitor. Manufacturing method of manganese oxide / carbon nanofiber composite obtained by coating carbon nanofibers with relatively inexpensive and eco-friendly nano-sized manganese oxide (MnO ₂ ), and high capacity super pseudocapacitor comprising the carbon nanofiber composite It relates to an electrode for a capacitor).

Electrospinning, carbonization, manganese dioxide, carbon nanofibers, deposition, stockpiling capacity, power density, power density

Description

Method for producing manganese oxide / carbon nanofiber composite and electrode for high capacity hybrid super pseudocapacitor comprising the carbon nanofiber composite {Method for producing complex of Manganese dioxide and carbon nanofiber and pseudo capacitor including the complex}

The present invention relates to a hybrid capacitor electrode for obtaining a high energy density and a high power density at the same time by exhibiting a complex function of a high-capacity pseudo capacitor and a double layer capacitor, and more specifically, to a carbon nanofiber having high electrical conductivity. Manufacturing method of manganese oxide / carbon nanofiber composite obtained by coating nano-size manganese oxide (MnO ₂ ) which is relatively inexpensive and environmentally friendly, and high capacity hybrid super pseudo capacitor electrode comprising the carbon nanofiber composite It is about.

The next generation energy storage system being developed recently uses electrochemical principles, which are representative of lithium (Li) secondary batteries and electrochemical capacitors.

Secondary batteries are excellent in terms of the amount of energy (energy density) that can be accumulated per unit weight or volume, but there is still much room for improvement in terms of the period of use, charging time, and the amount of energy (output density) that can be used per unit time. .

However, the electrochemical capacitor is smaller than the secondary battery in terms of energy density, but is very superior to the secondary battery in terms of use time, charging time, and output density.

Accordingly, in the case of electrochemical capacitors, research and development for improving the energy density are being actively conducted.

In particular, the supercapacitor is an energy storage power source device having unique performance characteristics in a region that conventional electrolytic capacitors and new secondary batteries do not have.

These supercapacitors are pseudocapacitances generated from electric double layer capacitors (EDLC) and electrochemical faradaic reactions using the principle of electric double layer according to the electrochemical storage mechanism. Are distinguished.

The electric double layer capacitor uses ions of the electrolyte solution physically adsorbed and desorbed while forming an electric double layer on the surface of the electrode. The electric double layer capacitor exhibits excellent power density due to the development of pores on the carbon surface. However, since charges are accumulated only on the surface of the electric double layer, there is a disadvantage that the energy density is lower than the metal oxide-based or electroconductive polymer-based supercapacitor using the Faraday reaction.

Metal oxide-based supercapacitors using pseudo capacitances are supercapacitors using metal oxides having multiple valences capable of redox. The supercapacitor of the metal oxide electrode using such pseudo capacitance has a higher specific capacitance than the double layer capacitor because the supercapacitor of the metal oxide electrode exhibits an accumulation mechanism in which protons move due to the oxidation / reduction reaction of the metal oxide. In addition, the electrode active material of the metal oxide-based supercapacitor has to move at a high speed in the electrolyte and the electrode ions and electrons required for redox during charging and discharging, it is preferable that the electrode interface has a high specific surface area, the electrode active material has a high electrical conductivity Is required.

Metal oxide electrode materials for pseudocapacitors reported to date include RuO ₂ , IrO ₂ , NiO _x , CoO _x , MnO ₂ , and the like.

Among the above electrode materials, RuO ₂ has the highest specific capacitance (720 F / g) compared with other electrode materials, but its application is limited to aerospace and military use due to the expensive raw materials.

As a result, many researches on electrode materials to replace expensive RuO ₂ have been ongoing in Korea, the US, and Japan.

The metal oxide electrode materials such as NiO _x , CoO _x , and MnO ₂ have poor capacity characteristics and thus have a lot of room for improvement. Accordingly, research on manufacturing and developing high capacity and low cost metal oxide electrodes is required. It is becoming.

Among them, relatively cheap and environmentally friendly manganese oxide (MnO ₂ ) has been spotlighted as an electrode material for capacitors, but there was a problem in that low yield and synthesis time are long as in the conventional metal oxide process. The electrode material of has a disadvantage of low specific capacitance and large resistance.

On the other hand, by increasing the porosity of the pseudo-capacitor electrode material to facilitate the movement of electrons to improve the output characteristics, and to increase the electrochemical utilization by shortening the diffusion distance and the reaction interface area of the reactive species through the nano-oxide of the metal oxide Capacity and output characteristics can be increased.

Accordingly, many studies have been conducted to develop a composite material of a carbon material and a metal oxide having a high electrical conductivity through the rapid electron transfer and having a three-dimensional porous structure capable of maximizing the impregnation of the electrolyte and the interface between the electrolyte and the active material. .

In particular, Korean Application No. 10-2004-0090286 relates to "manganese oxide-carbon nanocomposite composite method for manufacturing a high capacity supercapacitor electrode", in particular "carbon black, carbon nanotube, vapor growth carbon fiber (VGCF), etc." In the method for synthesizing a manganese oxide-carbon nanocomposite material for manufacturing a supercapacitor electrode formed by coating a manganese oxide on a carbon material, the manganese 7 contained in a reactor is dispersed by adding the carbon material to a solution, and then fixed during the reaction. The oxidation-reduction potential or pH change was measured while maintaining the temperature, and the pH value obtained through the potential or pH electrode with respect to the reference electrode obtained through the working electrode and the reference electrode installed in the reactor after dispersion of the carbon material was measured at the beginning of the measurement. The point of rapid drop is the starting point of the reaction, and the potential or pH value remains constant after the starting point of the reaction. In addition, to perform a synthetic reaction to coat the manganese oxide on the carbon material with the time of sudden drop as the completion of the reaction, in order to control the coating amount and coating thickness of the manganese oxide on the carbon material, at the same holding temperature and the amount of reactants used in advance Manganese oxide-carbon nano for manufacturing a high capacity supercapacitor electrode characterized in that the reaction is terminated at a specific reaction time by measuring the time from the reaction start time on the basis of the synthesis time from the reaction start point to the reaction completion point obtained. Composite material synthesis method. "

However, the method disclosed in the above patent still has a problem of coating a uniform metal oxide on a carbon material and not controlling the coating amount.

On the other hand, as described above, the carbon material for the electrochemical capacitor is mainly activated at a temperature of less than 1200 ℃ using an oxidizing gas or an inorganic salt, using coal or petroleum pitch, phenol resin, wood and carbon precursor precursor polymer as a starting material. Activated carbon and activated carbon fibers having a high specific surface area have been used.

In particular, in the case of carbon nanofibers, the pore distribution is more uniform than that of activated carbon, and it is possible to manufacture a high specific surface area and a paper, a felt, and a nonwoven fabric, thereby making a higher performance electrode active material.

In addition, carbon nanofibers having a nanographite structure have a relatively large specific surface area, a shallow depth of pores, and micropores having a size of 1-2 nm, so that metal oxide particles having a size of 20 nm or less are formed on the surface of carbon nanofibers. It is coated on to serve as a support that shows excellent adsorption performance and fast adsorption rate.

However, the activated carbon fibers produced and sold at present are mainly fabricated by using pitch, phenolic resin, etc. by melt-spinning or melt-blown spinning apparatus. Next, it is prepared by oxidative stabilization, carbonization or activation, but the fiber produced by the spinning method has a diameter of about 10 μm and is limited in effectively enhancing the specific surface area to volume.

In addition, when used as an electrode active material, the fiber must be crushed to add a binder or a conductive material, and in the case of a woven fabric, the fiber diameter of the manufactured fiber is relatively large and the electrode density is low, so that fast charge and discharge or high output characteristics can be obtained. Has the disadvantage of deterioration.

The present inventors have completed the present invention as a result of research efforts to solve the above disadvantages and problems of the prior art.

Accordingly, an object of the present invention is to prepare a carbon nanofiber having an ultrafine fibrous web and to coat the carbon nanofiber with a manganese oxide through a chemical method to shorten the electrode manufacturing process, as well as high electrode density and electrical double layer and pseudocapacity. It is to provide a manganese oxide coated carbon nanofiber manufacturing method and a manganese oxide coated carbon nanofiber prepared by the method and a hybrid supercapacitor electrode including the same, which can easily and inexpensively manufacture a high energy density high performance hybrid capacitor electrode.

Another object of the present invention is a manganese oxide coated carbon nanofibers and a manganese oxide coated carbon nanofibers prepared by a method of manufacturing the same, which can be immediately used as an electrode for pseudo-supercapacitors without addition, grinding, or weaving of a conductive agent or a binder. It is to provide an electrode for a supercapacitor.

Another object of the present invention is manganese oxide coated carbon nanofibers and manganese oxide coated carbon prepared by the method of manufacturing the same to control the coating thickness and size of the manganese oxide coated on the carbon material by controlling the reaction time, temperature, concentration The present invention provides an electrode for a nanofiber and an electric double layer supercapacitor including the same.

In order to achieve the above object, the present invention is a manufacturing step of manufacturing a polyacrylonitrile (PAN) -based carbon nanofibers; An immersion step of immersing the carbon nanofibers in a manganese acetate (Mn (Ace) ₂ )] solution; And a heat treatment step of heat-treating the carbon nanofibers which have undergone the immersion step. And it provides a manganese oxide / carbon nanofiber composite manufacturing method comprising the step of carbonizing the PAN flame-resistant fiber under a stream of nitrogen.

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In a preferred embodiment, the immersion step comprises the step of immersing the carbon nanofibers in a manganese acetate solution and maintaining for 1 to 5 hours at 60 ~ 70 ℃.

In a preferred embodiment, the heat treatment step heats the carbon nanofibers undergoing the immersion step at 200 ~ 400 ℃ in air.

In a preferred embodiment, the size and thickness of the manganese oxide coated on the carbon nanofibers can be controlled by controlling the concentration of the manganese acetate solution in the immersion step, the immersion reaction temperature and the immersion holding time and the heat treatment temperature of the heat treatment step have.

In a preferred embodiment, the manganese acetate solution contains 1 to 3% by weight of manganese acetate.

In a preferred embodiment, the solvent of the manganese acetate solution is added acetic acid to distilled water.

In a preferred embodiment, the solvent comprises distilled water: acetic acid in a volume ratio of 85:15 to 99: 1.

In another aspect, the present invention provides a manganese oxide / carbon nanofiber composite material, characterized in that produced by the method of any one of the above.

In addition, the present invention provides an electrode for an electric double layer supercapacitor comprising: a current collector: the manganese oxide / carbon nanofiber composite of any one of the above-mentioned formed in a nonwoven fabric disposed on the current collector; A glass fiber separator sandwiched between the positive electrode and the negative electrode; And it provides an electrode for an electric double layer supercapacitor comprising a water-soluble electrolyte solution.

In a preferred embodiment, the energy density is 7.1 Wh / Kg, the power density is 18 kW / Kg when the aqueous electrolyte solution is KOH 6M electrolyte solution.

The present invention as described above has the following excellent effects.

According to the manganese oxide coated carbon nanofiber manufacturing method of the present invention and the manganese oxide coated carbon nanofiber manufactured by the method and the electrode for an electric double layer supercapacitor including the same, a carbon nanofiber having an ultra-fine fiber web is produced through electrospinning By chemically coating manganese oxide on carbon nanofibers, the electrode manufacturing process can be easily and inexpensively manufactured using high electrode density as well as shortening of the electrode manufacturing process.

In addition, according to the manganese oxide coated carbon nanofibers of the present invention and the manganese oxide coated carbon nanofibers prepared by the method of manufacturing the same, and the electrode for an electric double layer supercapacitor including the same, hybrid super immediately without the addition of a conductive agent or a binder, crushing, weaving process It can be used as an electrode for a capacitor.

In addition, according to the manganese oxide-coated carbon nanofibers of the present invention and the manganese oxide-coated carbon nanofibers prepared by the method for manufacturing the same, and a hybrid supercapacitor electrode including the same, the manganese oxide coated on the carbon material through reaction time, temperature, and concentration control The coating thickness and size of can be controlled.

The terms used in the present invention were selected as general terms as widely used as possible, but in some cases, the terms arbitrarily selected by the applicant are included. In this case, the meanings described or used in the detailed description of the present invention are considered, rather than simply the names of the terms. The meaning should be grasped.

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

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

First, the manganese oxide coated carbon nanofiber composite of the present invention is electrospun and oxidatively stabilized PAN solution, which is a precursor, to produce PAN flame-resistant fiber and carbonized it under a nitrogen stream to produce carbon nanofibers, and produced carbon Nanofibers are obtained by impregnating and then heat-treating a solution of manganese acetate (Mn (Ace) ₂ ).

At this time, the polyacrylonitrile (PAN, molecular weight = 160,000) for fiber molding uses a modified acrylic containing 5-15% of a copolymer as well as a 100% homopolymer. As the composition of the copolymer, itaconic acid or methylacrylate may be used as the copolymer.

Example 1

Manufacture of Manganese Oxide / Carbon Nanofiber Composites

1. Carbon Nanofiber Manufacture

To prepare carbon nanofibers, PAN was dissolved in dimethyformamide (DMF) to prepare spinning solution. This PAN solution was prepared using a non-woven web composed of nanofibers using an electrospinning method. At this time, the electrospinning apparatus applied an applied voltage of 30 kV to the nozzle and the collector, respectively, and the distance between the spinneret and the collector was varied as needed about 10 to 30 cm.

The PAN spinning fiber obtained by electrospinning was supplied with compressed air at a flow rate of 5-20 mL per minute using a hot air circulation fan, and stabilized by maintaining it at 200-300 ° C for 1 hour at a temperature rising rate of 1 ° C per minute. The fiber was obtained.

The flame-resistant fiber obtained by oxidation stabilization was carbonized while raising the temperature to 700 to 1500 ° C. at an elevated temperature rate of 5 ° C. per minute in an inert atmosphere or in a vacuum, and then maintaining it for 1 hour.

2. Preparation of manganese acetate (Mn (Ace) ₂ ) solution

To prepare a solution of manganese acetate [(Mn (Ace) ₂ )], manganese acetate (Mn (Ace) ₂ ) and acetic acid (CH ₃ COOH) having a purity of 98% or more, manufactured by Aldrich, were used. To prepare manganese acetate solutions 1 to 3 with different concentrations, distilled water and acetic acid are first mixed at a ratio of 90:10, and 1 wt% of manganese acetate [Mn (Ace) ₂ ] is added thereto to prepare manganese acetate solution 1. was prepared in the same way as the addition of manganese acetate [Mn (Ace) _2] of 2wt% were prepared a manganese acetate solution 2 by the addition of manganese acetate [Mn (Ace) _2] of 3wt% to prepare a manganese acetate solution 3 .

3. Manufacture of Manganese Oxide / Carbon Nanofiber Composite (MnO ₂ coating on Carbon nanofiber complex)

Carbon nanofibers prepared in each of the prepared manganese acetate [Mn (Ace) ₂ ] solutions 1 to 3 were deposited, and then maintained at 60 to 70 ° C. for 1 to 5 hours and dried at room temperature.

After the heat treatment to 200 ~ 400 ℃ in air to prepare a manganese oxide / carbon nanofiber composite materials 1 to 3 coated with manganese oxide carbon nanofibers.

Experimental Example 1

Structural Analysis of Manganese Oxide / Carbon Nanofiber Composites

An electron micrograph of the manganese oxide / carbon nanofiber composite 2 prepared in Example 1 shows an effect of acetic acid through FIG. 2.

That is, on the surface of carbon nanofibers coated with manganese oxide by dissolving 1 wt% of Mn (Ace) ₂ in distilled water without acetic acid (FIGS. 2A-B), manganese oxides are agglomerated and the number of particles is large. It can be seen that relatively few manganese oxides are coated, whereas carbon nanofibers are immersed in a solution in which 2 wt% of Mn (Ace) ₂ is dissolved in a solvent containing acetic acid in distilled water. , As can be seen in Figure 2c-f it can be seen that the fine manganese oxide particles having a 4-8 nm diameter is uniformly distributed on the surface of the carbon nanofibers.

In addition, it can be seen that the faster the reaction rate in the immersed state, the higher the reaction temperature, the smaller the size of the particles due to insufficient time for the growth of fine manganese oxide particles.

Therefore, the particle size and coating thickness of the manganese oxide coated on the carbon nanofibers can be controlled by varying the amount of reactants, reaction rate and temperature in the immersed state.

In the graph of the energy dispersive X-ray spectroscopy (EDX) (FIG. 2G), the elements of C, O and Mn of the manganese oxide / carbon nanofiber composite material coated with carbon nanofibers were identified.

In addition, manganese oxides that were not coated on the surface of the carbon nanofibers and were not independently observed on the surface of the carbon nanofibers were observed through the transmission electron microscope (TEM) photograph (FIGS. 3A-F). It can be seen that it is coated.

The high specific capacitance and stable cycle life of EDLC can be expected through the interface of manganese oxide and carbon nanofibers that are uniformly distributed on the surface of carbon nanofibers.

In addition, 2θ was observed at 12, 37 and 66 ^° from FIG. 4 where the X-ray diffraction analysis (XRD) results of the manganese oxide / carbon nanofiber composite materials 1 and 2 obtained in Example 1 are shown, and through these three peaks, The composite material of manganese oxide / carbon nanofibers was found to be birnessite type manganese oxide structure (JCPDS 42-1317). In particular, the water absorbed by the manganese oxide reduces not only the electrochemical properties but also the thermal properties of the composite, so that the crystal water is removed by heat-treating the manganese oxide / carbon nanofiber composite at a suitable temperature, thereby producing a birnessite type manganese oxide having crystallinity. Optimizing the structure can improve performance. As such, manganese oxide having a birnessite structure has a layered structure, which is advantageous for removing / inserting hydrogen ions or metal cations, which are reactive species, compared to other manganese oxide phases (α phase, β phase, etc.). The amount is expected to be expressed.

Experimental Example 2

Information on the chemical composition and crystal of the manganese oxide / carbon nanofiber composite material was tested by X-ray photoelectron spectroscopy (XPS) and the results are shown in FIG.

It can be seen from Figure 5 (a) that the manganese oxide is coated on the carbon nanofibers through the overall binding energy of C1s, N1s, O1s, Mn2p3 at 0-1000 eV.

Experimental Example 3

Experiments were conducted to confirm the surface properties of the manganese oxide / carbon nanofiber composite and the results are shown in FIG. 6 and Table 1. FIG.

Figure 6a shows the BET adsorption-desorption isotherm of the manganese oxide / carbon nanofiber composite. The specific surface area of the carbon nanofibers prepared by electrospinning was 137 m ² / g, whereas the manganese oxide / carbon nanofiber composites 1 and 2 prepared in Example 1 showed specific surface areas of 96 and 233 m ² / g, respectively. gave.

As can be seen from Table 1, in the case of manganese oxide / carbon nanofiber composite material 1 (1% MnO ₂ / CNFs) obtained by immersing carbon nanofibers in manganese acetate solution 1 and then heat-treating at 150 to 280 ° C, manganese having a large particle size Oxides intercepted the surface of the carbon nanofibers, resulting in a smaller specific surface area than the first carbon nanofibers. However, manganese oxide-coated carbon nanofiber composite 2 (2% MnO ₂ / CNFs) immersed in carbon nanofibers in manganese acetate solution 2 and then heat-treated at 300 ~ 400 ° C. has a high specific surface area and a developed pore morphology. , Electrical conductivity was checked.

Therefore, the size and thickness of manganese oxide coated on carbon nanofibers can be controlled by varying the concentration of manganese acetate [Mn (Ace) ₂ ] solution used, the holding time and temperature of the immersion state. It can be seen that the control can optimize the manganese oxide particle size and coating pattern.

6b also shows porosity distribution of manganese oxide / carbon nanofiber composites. When 2 wt% of Mn (Ace) ₂ is used, it can be seen that most of the pore sizes are mesopores having 20 nm.

Surface Characteristics of Carbon Nanofibers (CNFs) Coated with Manganese Oxide Sample BET surface are (m ² / g) Pore width (nm) Pore volume (cm ³ / g) Conductivity (S / cm) CNFs 137 4.78 0.37 1.39 1% MnO ₂ / CNFs 96 4.61 0.11 3.63 2% MnO ₂ / CNFs 233 15.89 0.53 10.46

Example 2

Manufacture Electrode for Electric Double Layer Supercapacitor

The nonwoven fabric of manganese oxide / carbon nanofiber composite 2 prepared in Example 1 was cut, placed on a nickel foil current collector, sandwiched with a glass fiber separator between the positive electrode and the negative electrode, and impregnated with a 6M KOH aqueous electrolyte solution. The electrode for an electric double layer supercapacitor was produced.

Experimental Example 4

Electrochemical characteristics of the electrode for the electric double layer supercapacitor manufactured in Example 2 were analyzed and the results are shown in FIGS. 7 to 10.

First, FIG. 7 is a graph showing a measurement result of cyclic voltamogram (CV) in an electrolyte 6M KOH aqueous solution of an electrode for an electric double layer supercapacitor including manganese oxide coated carbon nanofiber composite 2. This electrode was measured in the voltage range of -0.5 to 0.5 V and 0 to 1.0 V, respectively.

FIG. 8 is a cyclic voltammetry method for scanning voltage ranges from 0 to 1V in order to examine the manganese oxide redox reaction of an electrode for an electric double layer supercapacitor including manganese oxide / carbon nanofiber composite material 2 at a scanning speed of 10 and 20 mV / sec. Each test is presented as a graph. From the results shown in FIG. 8, it can be seen that the pseudocapacitance characteristic of the redox reaction by the metal oxide at the electrode and electrolyte interface is used through two redox specific peaks at 0.68 and 0.42 V. FIG.

FIG. 9 shows a specific capacitance for an electric double layer supercapacitor comprising a manganese oxide coated carbon nanofiber composite 2 over a voltage range of 0-1 V and a scan rate of 1-100 mV / s through cyclic voltammetry. The graph is shown. The specific storage capacity is highly dependent on the content of manganese oxide and the specific surface area by activation conditions. From FIG. 9, it can be seen that the specific storage capacity was very good with about 480 F / g. These results are believed to be due to the characteristics of carbon nanofibers that provide high electrical conductivity due to the uniform dispersion of manganese dioxide.

FIG. 10 is a Ragon plot showing output and power density of a pseudocapacitor using an electrode for an electric double layer supercapacitor including manganese oxide / carbon nanofiber composite material 2. It can be seen that the KOH 6M aqueous solution electrolyte has a high energy density of 7.1 Wh / Kg, a power density of 18 kW / Kg, and a high power density capacitance.

From the above test results, the supercapacitor electrode including the manganese oxide / carbon nanofiber composite and the composite prepared by the manganese oxide / carbon nanofiber composite manufacturing method of the present invention improves not only specific capacitance but also output / power density. Able to know.

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.

1 is a flow chart schematically showing a method for producing a manganese oxide / carbon nanofiber composite according to an embodiment of the present invention,

FIG. 2 is a scanning electron microscope (SEM) photograph of a manganese oxide / carbon nanofiber composite obtained by using a manganese acetate solution in which 1 wt% of manganese acetate is added to distilled water, and in a solvent of H ₂ O / acetic acid (90:10). Scanning electron microscope (SEM) photographs of manganese oxide / carbon nanofiber composites obtained by using manganese acetate solution with 2 wt% manganese acetate (cf), 2 wt% manganese acetate in H ₂ O / acetic acid (90:10) solvent Graph (g) of energy dispersive X-ray spectroscopy (EDX) of manganese oxide / carbon nanofiber composite obtained when using this added manganese acetate solution,

3 is a photograph (a-f) of a transmission electron microscope (TEM) of a manganese oxide-coated carbon nanofiber composite material,

4 is a graph of X-ray diffraction analysis (XRD) of the manganese oxide coated carbon nano fiber composite material,

5 is an X-ray photoelectron spectroscopy (XPS) graph of a manganese oxide-coated carbon nanofiber composite having manganese oxide coated on carbon nanofibers;

6a is an adsorption-desorption isotherm graph of the manganese oxide coated carbon nanofiber composite,

6b is a porosity distribution graph of manganese oxide coated carbon nano fiber composites,

7a is a cyclic voltamogram graph of an electrolytic 6M KOH aqueous solution of manganese oxide / carbon nanofiber composite when the voltage range is -0.5 to 0.5 V,

7b is a cyclic voltamogram graph of an electrolyte 6M KOH aqueous solution of manganese oxide / carbon nanofiber composite when the voltage range is 0 to 1.0 V;

8a Cyclic voltamogram graph of redox reaction in electrolyte 6M KOH aqueous solution of manganese oxide coated carbon nanofiber composite when the scanning speed is 10 mV / s;

8b is a cyclic voltamogram graph of a manganese oxide-coated carbon nanofiber composite with redox reaction in an electrolyte 6M KOH aqueous solution at a scanning speed of 20 mV / s;

9 is a specific capacitance graph of the scanning speed of the manganese oxide-coated carbon nanofiber composite material in which manganese oxide is coated on carbon nanofibers in a voltage range of 0-1 V;

10 is a graph showing the power and power density of a pseudocapacitor using an electrode including a manganese oxide coated carbon nanofiber composite;

Claims (11)

A manufacturing step of manufacturing PAN-based carbon nanofibers; An immersion step of immersing the carbon nanofibers in a manganese acetate (Mn (Ace) ₂ )] solution; And It includes a heat treatment step of heat-treating the carbon nanofibers after the immersion step, The manufacturing step comprises the steps of electrospinning and oxidation-stabilizing the PAN solution, which is a precursor under high voltage, to prepare PAN flame-resistant fibers; And carbonizing the PAN flame-resistant fiber under a stream of nitrogen. delete The method of claim 1, The immersion step is a manganese oxide / carbon nanofiber composite manufacturing method comprising the step of immersing the carbon nanofibers in a manganese acetate solution for 1 to 5 hours at 60 ~ 70 ℃. The method of claim 1, The heat treatment step is a method of manufacturing a manganese oxide / carbon nano fiber composites, characterized in that the carbon nanofibers subjected to the immersion step heat treatment at 200 ~ 400 ℃ in air. The method of claim 1, The size and thickness of the manganese oxide coated on the carbon nanofibers can be controlled by controlling the concentration of the manganese acetate solution in the immersion step, the immersion reaction temperature and the immersion holding time and the heat treatment temperature in the heat treatment step. Oxide / carbon nanofiber composite manufacturing method. The method of claim 1, The manganese acetate solution is a manganese oxide / carbon nanofiber composite manufacturing method comprising 1 to 3% by weight of manganese acetate. The method of claim 6, The solvent of the manganese acetate solution is a manganese oxide / carbon nanofiber composite manufacturing method characterized in that acetic acid is added to distilled water. The method of claim 7, wherein The solvent is a manganese oxide / carbon nanofiber composite production method characterized in that it comprises distilled water: acetic acid in a volume ratio of 85: 15 to 99: 1. A manganese oxide / carbon nanofiber composite material prepared by the method according to any one of claims 1 and 3 to 8. In the electrode for electric double layer supercapacitor, Current collector: The manganese oxide / carbon nanofiber composite of claim 9 formed in a nonwoven fabric disposed on the current collector; A glass fiber separator sandwiched between the positive electrode and the negative electrode; And Hybrid supercapacitor electrode comprising a water-soluble electrolyte solution. 11. The method of claim 10, The electrode for a hybrid supercapacitor, characterized in that the energy density is 7.1 Wh / Kg, the power density is 18 kW / Kg when the aqueous electrolyte solution is KOH 6M electrolyte solution.

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