KR101342941B1 - Menufacture of high specific surface area and heteroatom-activated carbons - Google Patents

Abstract

The present invention relates to a method for producing a carbon body using a mixture of poly (vinylidene fluoride) and melamine resin as a precursor, and to a method for producing a carbon body for a high capacity capacitor electrode in which heteroatomic content is simply controlled by a single carbonization process. To provide.
According to the present invention as described above, it is possible to produce a high specific surface area of the activated carbon through a single process that does not require a chemical activation process, and a mixture of two polymer precursors having a functional group (poly (vinylidene fluoride) / melamine) By using the method for producing activated carbon containing heteroatoms on the surface of the activated carbon, and using the same, there is an effect of producing an electrode for a supercapacitor having improved electrochemical properties.

Description

MENUFACTURE OF HIGH SPECIFIC SURFACE AREA AND HETEROATOM-ACTIVATED CARBONS}

The present invention relates to a method for producing a carbon electrode material for a high capacity capacitor, more specifically, a precursor for the introduction of poly (vinylidene fluoride) and heteroatoms as precursors for carbon bodies having a high specific surface area through micropores. The present invention relates to a method for producing carbon atoms containing heteroatoms using a mixture of low melamine resins, and to simplifying a single carbonization process by changing the content of poly (vinylidene fluoride) / melamine mixture for high capacity energy storage carbon bodies. It relates to the production of a carbon body for a high capacity capacitor electrode is heteroatomic content is controlled. In addition, the present invention relates to a method for producing a carbon body having a very high specific surface area and heteroatoms through a single carbonization process that does not require an activation step using an additional activator for the production of the existing high specific surface area activated carbon. Finally, the present invention relates to a method for producing a carbon electrode having an excellent energy storage capacity using a carbon body having a high specific surface area and heteroatoms.

A super capacitor is a capacitor having a very large capacitance as compared with a conventional capacitor, and is called an ultra capacitor or an ultra high capacity capacitor. The supercapacitor is an energy storage device having an intermediate characteristic between an electrolytic capacitor and a secondary battery. The supercapacitor is capable of rapid charging and discharging. Energy storage devices are in the spotlight. Due to these characteristics, supercapacitors can be applied from small-capacity electronic devices to large-capacity products such as electric vehicles (EVs), hybrid electric vehicles (HEVs), and fuel cell vehicles (FCVs). The utility of capacitors is increasing day by day.

The super capacitor is commercialized since the 1980s compared to electrolytic capacitors and lithium secondary batteries, and its development history is comparatively short. However, as a electrode material, a novel electrode material such as metal oxide including conductive carbon, conductive polymer, etc. and a hybrid type using asymmetric electrode The development speed of the product is very fast. In recent years, a product having an energy density exceeding that of a Ni-MH battery has also been developed, and a high power density and a low energy density, which is known as a disadvantage of a conventional supercapacitor, are greatly improved.

However, due to the low energy density of supercapacitors, application to various fields is still limited. Therefore, research is being actively conducted on hybrid systems using surface modification, transition metals, and conductive polymerization to improve energy storage of existing carbon materials (theoretical capacity: 372 Fg ^{?? 1} ). Among these various reforming methods, the use of transition metals and conductive polymers is relatively expensive, and many studies are underway to improve energy density through surface modification. In particular, heteroatoms such as nitrogen atoms may be introduced to the carbon surface to improve carbon materials. Many studies have been reported to introduce the pseudocapacitance with the basic characteristics of electric double layer capacitance.

However, the surface modification of the carbon material also requires a secondary process such as surface activation, and due to the problem of environmental pollution due to the use of expensive equipment or chemical reagents in the surface treatment process has an additional purification process. Accordingly, the present inventors have excellent energy storage capacity and filling capacity when manufacturing a carbon material containing a high specific surface area and heteroatoms only through the first carbonization process using a mixture of two polymer precursors to compensate for the above disadvantages of the surface treatment of the carbon material. The inventors have found that they exhibit discharge cycle characteristics and have completed the present invention.

Meanwhile, Korean Patent No. 10-0517021 (Preparation of Carbon Nanofibers by Electrostatic Radiation and Electrode of Electrode for Double Layer Capacitors) as a prior art relating to the preparation of electrodes for activated carbon and capacitor, Korean Patent No. 10- 0650618 (a method for producing activated carbon having a high specific surface area for capacitor electrodes).

An object of the present invention is to provide heteroatoms containing heteroatoms using a mixture of poly (vinylidene fluoride) and melamine resin as precursors for the introduction of heteroatoms as precursors for carbon atoms having a high specific surface area through micropores. The present invention provides a method for manufacturing a supercapacitive carbon electrode having excellent electrochemical and cycle characteristics using the method.

In order to achieve the above object, the present invention (1) poly (vinylidene fluoride) and melamine is dissolved in N-methyl pyrrolidone (N-methyl pyrrolidone) and stirred, and then Putting and drying to prepare an activated carbon precursor; and (2) carbonizing the activated carbon precursor dried by the step (1) using a tubular electric furnace; It provides a method for producing activated carbon comprising a high specific surface area and heteroatoms in a single process comprising a; and (3) fine grinding the activated carbon carbonized in the step (2) using a mortar.

Melamine is mixed in an amount of 25 to 200 parts by weight based on 100 parts by weight of poly (vinylidenefluoride) in the step (1).

In step (1), poly (vinylidene fluoride) and melamine are dissolved in N-methylpyrrolidone and stirred at room temperature for 12 to 24 hours, and placed in a mold. It is characterized by drying at 80 to 120 ℃.

The activated carbon precursor dried in the step (2) is characterized in that carbonized for 90 minutes to 150 minutes at 800 to 900 ℃ using a tubular electric furnace. However, a temperature increase rate shall be 10 degree-C / min.

In addition, the present invention comprises the steps of (1) mixing the activated carbon, carbon black and poly (vinylidene fluoride) prepared by the method for producing an activated carbon containing a high specific surface area and heteroatoms by the single process; and (2) Slurrying the mixture mixed by the step (1) using N-methylpyrrolidone; and (3) mixing the mixture slurry prepared by the step (2) on the susmesh using a film casting method. Applying; And (4) drying the electrode prepared by the step (3).

Activated carbon, carbon black and poly (vinylidene fluoride) used in the step (1) is characterized in that consisting of 60 to 80% by weight, 10 to 30% by weight and 5 to 15% by weight, respectively.

According to the present invention as described above, using a poly (vinylidene fluoride) as a precursor, unlike the existing activated carbon, it is possible to produce a high specific surface area of activated carbon through a single process, which does not require a chemical activation process, having a functional group Using a mixture of two polymer precursors (poly (vinylidene fluoride) / melamine) to provide a method for producing activated carbon containing heteroatoms on the surface of the activated carbon, by using this electrode for supercapacitors with improved electrochemical properties There is an effect that can be prepared.

1 is a TEM image of a microporous carbon body including heteroatoms.
2 is a graph showing the results of surface analysis of microporous carbon bodies including heteroatoms.
3 is a graph showing the pore characteristics of the microporous carbon body including heteroatoms.
4 is a charge and discharge graph of an electrode prepared from microporous carbon bodies including heteroatoms.
5 is a graph showing an energy storage amount of an electrode prepared from microporous carbon bodies including heteroatoms.
6 is a graph showing the cycle characteristics of the electrode prepared from the microporous carbon body including heteroatoms.

Hereinafter, the present invention will be described in detail.

The present invention provides a method of easily controlling the content of heteroatoms having a high specific surface area in a single carbonization process in the production of activated carbon using a poly (vinylidene fluoride) and melamine mixture as a precursor of activated carbon. The micropores of activated carbon depend on the poly (vinylidene fluoride) used as precursor, and the content of heteroatoms depends on the content of melamine used as another precursor. When carbonizing a mixture of two precursors through carbonization, activated carbon having a high specific surface area can be produced without additional chemical activation, unlike conventional activated carbon. In addition, an electrode for a supercapacitor may be manufactured using the activated carbon, and the electrochemical characteristics of the electrode may be measured.

According to the present invention, a method for preparing activated carbon containing a high specific surface area and heteroatoms by (1) poly (vinylidene fluoride) and melamine to N-methyl pyrrolidone Dissolving and stirring, putting in a mold and drying to prepare an activated carbon precursor; and (2) carbonizing the activated carbon precursor dried by the step (1) using a tubular electric furnace; And (3) fine grinding the activated carbon carbonized by the step (2) using mortar.

Melamine may be mixed in an amount of 25 to 200 parts by weight based on 100 parts by weight of poly (vinylidenefluoride) in step (1).

In step (1), poly (vinylidene fluoride) and melamine are dissolved in N-methylpyrrolidone and stirred at room temperature for 12 to 24 hours, and placed in a mold. May be dried at 80 to 120 ° C. Meanwhile, N-methyl pyrrolidone, which is used as a solvent, is a solvent having a very high boiling point. When the drying temperature is less than 80 ° C., the solvent is not completely dried even after drying, There is a problem that uniform carbon samples cannot be made when carbonizing using electric furnaces, and even when the drying temperature exceeds 120 ℃, there is a problem that no uniform carbon samples can be produced when carbonizing.

The activated carbon precursor dried in the step (2) may be carbonized at a temperature increase rate of 10 ° C./min for 90 minutes to 150 minutes at 800 to 900 ° C. using a tubular electric furnace. However, it is preferable to carbonize at a temperature rising rate of 10 ° C./min at 850 ° C. for 120 minutes.

In addition, the present invention comprises the steps of (1) mixing the activated carbon, carbon black and poly (vinylidene fluoride) prepared by the method for producing activated carbon comprising a high specific surface area and heteroatoms by the single process; and (2) Slurrying the mixture mixed by the step (1) using N-methylpyrrolidone; and (3) mixing the mixture slurry prepared by the step (2) on the susmesh using a film casting method. Applying; And (4) drying the electrode prepared by the step (3).

Activated carbon, carbon black and poly (vinylidene fluoride) used in step (1) may be composed of 60 to 80% by weight, 10 to 30% by weight and 5 to 15% by weight, respectively. Preferably 70% by weight activated carbon, 20% by weight carbon black, and 10% by weight poly (vinylidene fluoride).

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are merely illustrative of the present invention and that the scope of the present invention is not construed as being limited by these embodiments.

(1) Preparation of Activated Carbon Precursor Mixtures

The precursor mixture of activated carbon used in the present invention can be either a solid phase mixing or a liquid phase mixing, and preferably liquid phase mixing is used for uniform mixing. Poly (vinylidene fluoride) and melamine as precursors were dissolved in N-methylpyrrolidone as a solvent and stirred at room temperature for 12 to 24 hours, and then the homogeneous mixture was put in a mold and dried at 80 to 120 ° C to obtain activated carbon. Used as precursor for.

(2) Preparation of activated carbon with high specific surface area and heteroatoms through single carbonization process

The dried polymer precursor was prepared by the carbonization process using a tubular electric furnace. The polymer precursor was placed in the center of the tubular electric furnace and carbonized under nitrogen atmosphere at 850 ° C. for 2 hours, and the temperature increase rate was fixed at 10 ° C./min. The activated carbon prepared after carbonization was finely ground using mortar. The specific surface area and the hetero atom content of the activated carbon prepared in this way can be controlled by the content ratio of poly (vinylidene fluoride) and melamine. In addition, the content of poly (vinylidene fluoride) must be high for high specific surface area activated carbon, and the content of heteroatoms increases with increasing melamine content.

(3) Fabrication of supercapacitive electrodes using activated carbon with high specific surface area and heteroatoms

Activated carbon, carbon black, and poly (vinylidene fluoride) having a high specific surface area and heteroatoms for the production of electrodes of supercapacitors contain 70% by weight, 20% by weight, and 10% by weight of N-methylpyrrolidone as a solvent. It was prepared by mixing and applying to the sus mesh used as the current collector using a film casting method. The prepared negative electrode was dried at 110 ° C. for one day to completely remove N-methylpyrrolidone and used.

Example 1.

     The poly (vinylidene fluoride) / melamine mixture was dissolved in N-methylpyrrolidone as a solvent with a weight ratio of 1: 0.25, and stirred at room temperature for 12 to 24 hours, and then the uniform mixture was put into a mold at 80 to 120 ° C. The dried precursor was used as a precursor for activated carbon, and the dried precursor was used to prepare activated carbon through a carbonization process using a tubular electric furnace. The precursor was placed in the center of the tubular electric furnace and carbonized under nitrogen atmosphere at 850 ° C. for 2 hours, and the temperature increase rate was fixed at 10 ° C./min. Activated carbon produced after carbonization was finely pulverized using mortar.

Activated carbon, carbon black, and poly (vinylidene fluoride) prepared above for preparing the negative electrode of the supercapacitor were mixed with 70% by weight, 20% by weight, and 10% by weight of N-methylpyrrolidone as a solvent. It was prepared by applying to the sus mesh used as the current collector using the film casting method. The prepared negative electrode was dried at 110 ° C. for one day to completely remove N-methylpyrrolidone and used.

Example 2.

Activated carbon containing a high specific surface area and heteroatoms was prepared in the same manner as in Example 1 with the weight ratio of the poly (vinylidene fluoride) / melamine mixture being 1: 0.5, and a supercapacitor electrode was prepared using the same.

Example 3.

Activated carbon containing a high specific surface area and heteroatoms was prepared in the same manner as in Example 1 with a weight ratio of poly (vinylidene fluoride) / melamine mixture 1: 1, to prepare an electrode for a supercapacitor.

Example 4.

An active carbon including a high specific surface area and heteroatoms was prepared in the same manner as in Example 1 with the weight ratio of the poly (vinylidene fluoride) / melamine mixture being 0.5: 1, to prepare an electrode for a supercapacitor.

On the other hand, to compare the surface characteristics, pore characteristics and electrochemical characteristics of high specific surface area activated carbon containing no hetero atoms, the following comparative examples were prepared.

Comparative Example 1

Using poly (vinylidene fluoride) as a precursor, a high specific surface area activated carbon was prepared in the same manner as in Example 1, and an electrode for a supercapacitor was prepared using the same.

Tables 1 and 2 show the surface, pore characteristics, and capacitance values of the high specific surface area activated carbon prepared as in Examples 1 to 4 and Comparative Example 1, the active carbon including the high specific surface area and heteroatoms, respectively.

As shown in Table 1, it was confirmed that the content of the nitrogen group contained in the activated carbon increases with the increase of the content of melamine.

As can be seen from Table 2, the specific surface area of activated carbon decreased with increasing melamine content, but the energy storage amount increased, which may be due to the effect of pseudocapacitance according to the introduction of nitrogen groups. However, it was confirmed that the energy storage amount of activated carbon is significantly decreased when the excessive amount of melamine is added, which may be due to the decrease in mobility of electrolyte ions due to the very low specific surface area and the decrease of pore characteristics of activated carbon.

In addition, as a result of confirming the cycle characteristics of the electrode using the sample of Example 2, it was confirmed that even after 1000 charge / discharge experiments, the decrease in capacitance value was very low, about 5.8%, from which a high ratio was obtained through a single process. The excellent cycle characteristics of the activated carbon electrode containing the surface area and heteroatoms were confirmed (see FIGS. 1 to 6).

Having described specific portions of the present invention in detail, it will be apparent to those skilled in the art that this specific description is only a preferred embodiment and that the scope of the present invention is not limited thereby. It will be obvious. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (6)

(1) mixing 50 parts by weight of melamine with respect to 100 parts by weight of poly (vinylidenefluoride);
(2) The mixture prepared in step (1) was dissolved in N-methyl pyrrolidone and stirred at room temperature for 12 to 24 hours, and then dried at 80 to 120 ° C to activate an activated carbon precursor. Preparing a;
(3) carbonizing the activated carbon precursor prepared by step (2) using a tubular electric furnace;
(4) finely grinding the activated carbon carbonized in step (3) using mortar;
(5) mixing 70% by weight of activated carbon pulverized by step (4), 20% by weight of carbon black and 10% by weight of poly (vinylidene fluoride);
(6) slurrying the mixture prepared in step (5) using N-methylpyrrolidone;
(7) applying the mixture slurry prepared by step (6) to the susmesh using a film casting method; And
(8) drying the electrode produced by the step (7); manufacturing method of a supercapacitor electrode comprising a.
delete delete The method of claim 1,
Method for producing a supercapacitor electrode, characterized in that the carbonized activated carbon precursor in step (3) using a tubular electric furnace carbonized for 90 minutes to 150 minutes at 800 to 900 ℃
However, a temperature increase rate shall be 10 degree-C / min.
















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