KR102094204B1 - Preparation method of nitrogen contained porous carbon fiber for supercapacitor electrode materials - Google Patents

Abstract

The present invention relates to a method for producing a carbon fiber having a high capacitance that can be used as a supercapacitor electrode material, comprising: (a) preparing a raw material solution by dissolving PAN and PVDF polymers; (b) spinning the dissolved polymer solution to produce polymer fibers; (c) carbonizing the polymer fiber.
According to the present invention as described above, it is possible to manufacture a porous carbon fiber containing nitrogen having a high electric capacity with only a simple step than a conventional electrode material manufacturing method.

Description

Manufacturing method of nitrogenous porous carbon fiber for supercapacitor electrode material. {PREPARATION METHOD OF NITROGEN CONTAINED POROUS CARBON FIBER FOR SUPERCAPACITOR ELECTRODE MATERIALS}

The present invention relates to the production of a porous carbon fiber containing nitrogen that can be used as an electrode material of a supercapacitor, and more specifically, polyacrylonitrile (PAN) and polyvinylidene fluoride (Polyvinylidene fluoride, PVDF) It is intended to be used as an electrode material for a supercapacitor by mixing a polymer at a certain ratio to produce a polymer fiber and then producing a porous carbon fiber containing nitrogen through a carbonization process.

Recently, according to the limitations of crude oil and eco-friendly energy policies, energy policies for reducing fossil raw materials have been announced and implemented. In Korea, more than 97% of the country's total energy depends on imports, the annual average energy consumption growth rate is 1.1%, and 83% of the total energy source emits a lot of carbon dioxide as fossil fuels, resulting in greenhouse gas emissions under the Convention on Climate Change. Industrial competitiveness is weakening due to regulations and strengthening of international environmental regulations. In order to overcome this situation, the need for the development of high-performance energy storage devices has emerged as electric vehicles and smart grids have recently attracted attention.

Among these energy storage devices, a supercapacitor is a capacitor having a very large storage capacity and is called an ultracapacitor or an ultracapacitor capacitor. Supercapacitors have a short history of development, but research and development are still actively conducted in using various materials as electrode materials. In particular, activated carbon is an electrode material of a supercapacitor that has been traditionally used, and has a potential as an electrode material in that it is cheaper than metal materials, has various raw materials, and is easy to modify properties.

Korean Registered Patent No. 10-1418877

An object of the present invention is to provide a new supercapacitor electrode material by manufacturing porous carbon fibers containing nitrogen having a high electric capacity through a simple process of electrospinning and carbonization.

In order to achieve the above object, the present invention comprises (a) dissolving PAN and PVDF polymer to prepare a raw material solution, (b) spinning the dissolved polymer solution to produce polymer fibers and (c) the It provides a step of carbonizing the polymer fibers.

The step (a) may be to prepare a raw material solution by mixing and dissolving PAN and PVDF polymer in a mass ratio of 1 to 9: 1 to 3.

The step (b) may be to produce a polymer fiber by electrospinning the dissolved polymer solution.

Step (c) may be to carbonize the polymer fiber at a temperature of 900 to 1200 ℃.

According to the present invention as described above, by mixing the PAN and PVDF at a constant rate and manufacturing the carbon fiber through a simple process of carbonization, it is possible to manufacture a carbon fiber having a higher electric capacity than the conventional carbon fiber.

1 is an SEM photograph of a porous carbon fiber containing nitrogen of the present invention.
FIG. 2 is a graph of cyclic voltammetry (CV) and galvanostativ charge / discharge (GCD) of fibers having the highest electrical capacity among porous carbon fibers containing nitrogen of the present invention.

Hereinafter, the present invention will be described in detail.

The method for producing carbon fiber having a high electric capacity of the present invention includes (a) dissolving PAN and PVDF polymers to prepare a raw material solution, (b) spinning the dissolved polymer solution to produce polymer fibers, and (c) It provides a step of carbonizing the polymer fibers.

Step (a) may be to prepare a raw material solution by mixing and dissolving PAN and PVDF in a mass ratio of 1 to 9: 1 to 3. At this time, if the mass ratio of PVDF is too high, the yield of carbon fiber is rapidly reduced during carbonization, so the mass ratio of PVDF is preferably 3 or less. PAN and PVDF are mixed at the above mass ratio to make a total of 5 g, which is completely dissolved by stirring in a 10 to 50 mL volume of DMF solution for 6 to 24 h.

The step (b) may be to prepare polymer fibers by electrospinning the dissolved polymer solution. At this time, 12 mL of the dissolved polymer solution is filled in a syringe, and the supply voltage of the electrospinning device is 5 to 40 kV, preferably 15 to 40 kV. Then, the injection rate of the polymer solution is 0.2 to 5 mL / h, preferably 0.2 to 2 mL / h, and the rotation speed of the fiber collector is 100 to 1000 rpm, preferably 300 to 1000 rpm, to form a mat type polymer fiber. To prepare. At this time, the temperature is maintained at 25 ± 2 ℃ and the relative humidity at 50 ± 5%.

Step (c) may be to carbonize the polymer fibers at a temperature of 900 to 1200 ℃. The mat-type polymer fiber obtained in step (b) is carbonized at a temperature of 600 to 1200 ° C for 1 to 5h, preferably carbonized at 900 to 1000 ° C for 2 to 4h. At a temperature below 600 ° C, carbonization, which is the purpose of carbonization, is not generated, so carbonization does not proceed. At this time, in order to stably carbonize the polymer fiber, a stabilization process is performed at 280 ° C for 10 minutes during the carbonization process.

In the case of the present invention, carbon fibers are prepared by using the PAN polymer containing nitrogen and the PVDF polymer exhibiting porosity through carbonization as precursors. In this case, it is possible to control the nitrogen content and porosity by controlling the mixing ratio of PAN and PVDF and the carbonization temperature. Eventually, the oxidation / reduction reaction is induced due to the introduced nitrogen atom, and the electrolytic mobility at the electrode surface increases due to the pore structure generated by carbonization of PVDF, resulting in higher electric capacity.

Hereinafter, the present invention will be described in more detail through examples and measurement examples. These examples and measurement examples are only for illustrating the present invention, it is apparent to those skilled in the art that the scope of the present invention is not to be construed as limited by these examples and measurement examples. will be.

Example 1.

PAN and PVDF polymer were mixed at a mass ratio of 95: 5, and a total of 5 g was added to a 10 mL DMF solution and stirred for 6 h. After filling the syringe with 12 mL of the dissolved polymer solution, a mat-type polymer fiber was prepared by supplying the electrospinning device with a supply voltage of 5 kV, a polymer solution with a scanning speed of 5 mL / h, and a collector rotation speed of 100 rpm. At this time, the temperature is maintained at 25 ± 2 ℃ and the relative humidity at 50 ± 5%. The obtained mat-type polymer fiber is carbonized at 600 ° C. for 1 h to prepare a porous carbon fiber containing nitrogen, which is stabilized at 280 ° C. for 10 minutes during the carbonization process. In order to measure the performance of the prepared nitrogenous porous carbon fiber as an electrode material of a supercapacitor, an electrochemical property is measured under a 3 electrode using a KOH solution as an electrolyte using a nickel support. At this time, a platinum electrode is used as a reference electrode, and an Ag / AgCl electrode is used as a counter electrode.

Example 2.

The same procedure as in Example 1 was carried out, but the mixture was stirred for 9 h, and the injection rate of the polymer solution was 3 mL / h during electrospinning, and carbonization was performed at 800 ° C.

Example 3.

The same procedure as in Example 2 was carried out, but the mass ratio of PAN and PVDF was 9: 1, and 20 mL of DMF was used to dissolve. When electrospinning, a voltage of 10 kV was supplied, the rotational speed of the collector was set to 300 rpm, and carbonization was performed by carbonizing for 2 h.

Example 4.

The same procedure as in Example 3 was carried out, but the mixture was stirred for 12 h, the supply voltage was 15 kV during electrospinning, and the scanning speed was 2 mL / h, and carbon fibers were prepared by carbonization at 900 ° C.

Example 5.

The procedure was performed in the same manner as in Example 4, but a 25 mL DMF solution was used, the injection rate was 0.8 mL / h during electrospinning, and carbonization was performed at 1000 ° C. for 3 h.

Example 6.

The same procedure as in Example 5 was carried out, but the mass ratio of PAN and PVDF was 8: 2, the supply voltage was 25 kV during electrospinning, the scanning speed was 0.5 mL / h, and the rotation speed of the collector was 500 rpm.

Example 7.

The same procedure as in Example 6 was carried out, but the mass ratio of PAN and PVDF was 7: 3, and the mixture was dissolved for 18 h using 40 mL of DMF. During the electrospinning, the rotational speed of the collector was 700 rpm, and carbonization was performed for 4 h.

Example 8.

The same procedure as in Example 7 was carried out, but the mass ratio of PAN and PVDF was 5: 5, and dissolved using 50 mL of DMF. When electrospinning, the supply voltage was 35 kV and carbonized at 1100 ° C. for 5 h.

Example 9.

The same procedure as in Example 8 was carried out, but the polymer solution was stirred for 24 h, and when electrospinning, polymer fibers were prepared with a supply voltage of 40 kV, a scanning speed of 0.2 mL / h, and a collector rotation speed of 1000 rpm. Carbonization proceeded at 1200 ° C.

Comparative Example 1.

The same procedure as in Example 5 was carried out, but the carbon fiber containing nitrogen was prepared by setting the mass ratio of PAN and PVDF to 10: 0.

Comparative Example 2.

The same procedure as in Example 5 was performed, but a mat-type polymer fiber without carbonization was prepared.

Measurement Example 1. The shape of the porous carbon fiber containing nitrogen of the present invention

The shape of the porous carbon fiber containing nitrogen prepared in the present invention was observed through scanning electron microscopy (SEM, Hitachi, SU 8010) (FIG. 1).

Measurement Example 2. Electrochemical properties of the porous carbon fiber containing nitrogen of the present invention

Cyclic voltammetry (CV) and galvanostativ charge / discharge (GCD) test (Ivium Technologies) were used to measure the electrochemical properties of the porous carbon fiber containing nitrogen prepared in the present invention (FIG. 2).

Table 1 below shows the operating conditions and measurement conditions of Examples 1 to 9 and Comparative Examples 1 and 2.

Sample name PAN: PVDF ratio DMF volume
(mL) Stirring time
(h) Electric radiation supply voltage
(kV) Electrospinning speed
(mL / h) Collector rotation speed
(rpm) Carbonization temperature
(℃) Carbonization time
(h) Example 1 95: 5 10 6 5 5 100 600 One Example 2 95: 5 10 9 5 3 100 800 One Example 3 9: 1 20 9 10 3 300 800 2 Example 4 9: 1 20 12 15 2 300 900 2 Example 5 9: 1 25 12 15 0.8 300 1000 3 Example 6 8: 2 25 12 25 0.5 500 1000 3 Example 7 7: 3 40 18 25 0.5 700 1000 4 Example 8 5: 5 50 18 35 0.5 700 1100 5 Example 9 5: 5 50 24 40 0.2 1000 1200 5 Comparative Example 1 10: 0 25 12 15 0.8 300 1000 3 Comparative Example 2 9: 1 25 12 15 0.8 300 - -

Table 2 below shows the results of measuring the electrochemical properties of the carbon fibers prepared by Examples 1 to 9 and Comparative Examples 1 and 2.

Nitrogen content
(wt.%) Specific surface area
(m ² / g) Electric capacity
(F / g) Example 1 8.46 7 12.7 Example 2 7.22 8 50.0 Example 3 7.22 37 53.3 Example 4 7.19 45 110.7 Example 5 7.01 104 187.5 Example 6 5.01 118 45.8 Example 7 4.52 152 81.2 Example 8 3.73 201 42.1 Example 9 3.27 228 78.1 Comparative Example 1 7.80 4 32.5 Comparative Example 2 10.30 - 23.5

Hereinafter, the results of comparing the electrochemical properties of the carbon fibers produced by Examples 1 to 9 and Comparative Examples 1 and 2 will be described.

According to Table 2 above, it can be seen that in Examples 2 to 5, where the nitrogen content is almost similar, the electric capacity also increases as the specific surface area increases, and the carbon fiber produced by Example 5 shows the highest electric capacity. . This is because the porous structure due to the PVDF polymer was better formed due to the increase in the carbonization temperature. However, in the case of Comparative Example 1 having a similar nitrogen content, the specific surface area is very low because the PVDF polymer that provides the porous structure to the carbon fiber is not used, and thus, the electrical capacity is remarkably low. In addition, in the case of Comparative Example 2, although the nitrogen content was the highest, the electric capacity was very low, because it was judged that the PVDF polymer providing the porous structure was used in a very small proportion and the carbonization process to make the porous structure was not performed.

As described above, specific parts of the present invention have been described in detail. For those skilled in the art, this specific technique is only a preferred embodiment, and it is obvious that the scope of the present invention is not limited thereby. something to do. Therefore, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims (4)

(a) preparing a raw material solution by dissolving polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF) polymer;
(b) spinning the dissolved polymer solution to produce polymer fibers; And
(c) carbonizing the polymer fiber,
In step (a), a PAN and PVDF polymer are mixed and dissolved in a mass ratio of 9: 1 to prepare a raw material solution,
The step (c) is a method of manufacturing a carbon fiber having a high electric capacity, characterized in that the polymer fiber is carbonized at a temperature of 1000 ℃.
delete According to claim 1,
The step (b) is a method for producing a carbon fiber having a high electric capacity, characterized in that the polymer fiber is produced by electrospinning the dissolved polymer solution.
delete

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