KR20220129785A - Manufacturing method of continuous skeletal porous carbon material for application to supercapacitor - Google Patents

Abstract

The present invention relates to a preparation method of a continuous skeletal porous carbon material in which the structure of an epoxy resin does not collapse in a carbonization and activation process by adding nanocarbon to the epoxy resin and a continuous skeletal porous carbon material having binary pores prepared according to the preparation method. The continuous skeleton porous carbon material can improve electrical conductivity by the addition of nanocarbon and a continuous skeleton and can increase charge mobility by having the binary pores at the level of several to several tens of μm and several nm.

Description

Manufacturing method of continuous skeletal porous carbon material for application to supercapacitor

The present invention provides a method for producing a continuous skeletal porous carbon material in which the structure of the epoxy resin does not collapse in the carbonization and activation process by adding nano-carbon to an epoxy resin, and a continuous skeletal porous carbon material having binary pores prepared according to the manufacturing method , and its application to supercapacitors.

Graphene is a kind of carbon nanoparticles called a new dream material, and has excellent properties such as high electrical conductivity, thermal conductivity, and high strength. Graphene is a structure in which 6 carbon atoms are gathered to form a hexagonal honeycomb and are connected in a plate shape. Graphene is composed of a single layer, and the form of stacked graphene is graphite, which is commonly seen around. Graphite, also called graphite, is a good starting material for obtaining large amounts of graphene because of its low price. Graphene is produced from graphite, and the simplest method is to remove it from graphite with a scotch tape, and the commonly used methods are a method of obtaining chemically oxidized graphite by reducing it and a method of chemical vapor deposition on a metal substrate. There are ways to grow fins. Graphene obtained in this way is widely used as a material for electronic devices and energy storage devices because of its high conductivity.

Epoxy resin is one of the most important crosslinked polymer materials due to its excellent physical properties such as strong adhesion, high tensile strength and toughness, high chemical/thermal stability, morphological stability, excellent creep properties, and solvent resistance. Adhesives and coatings in various electrical and electronic products/parts, aerospace field, automobile field, military field, sporting goods/living goods field, civil engineering/construction field, machinery field due to excellent process characteristics and economical price in addition to these excellent properties , paints, laminates, castings, molded products, etc.

Porous carbon materials for application as energy storage materials such as supercapacitor anode materials are important in terms of charge storage and charge mobility, respectively, in terms of pore development at the level of several nanometers and hundreds of nanometers to several micrometers, and in terms of electrical conductivity, It is advantageous to have a fin addition and a continuous backbone. In the case of activated carbon currently on the market, coke is produced through carbonization and activation processes. Since the pore structure is formed through the top-down activation process, pores at the level of several to tens of nm are formed, and pores at the micrometer level are formed. It is difficult to achieve continuous pore structure control including

In this regard, U.S. Patent Application Publication No. 2020-0010633 discloses that by mixing a specific epoxy resin component in a specific range as an epoxy resin component, carbon fiber having excellent moldability and heat resistance and excellent mechanical properties such as tensile strength and compressive strength Although disclosed with respect to an epoxy resin composition suitably used for a reinforced composite material, a conventional material using an epoxy resin has a problem in that the polymer structure collapses at 700° C. or higher.

US Patent Publication No. 2020-0010633

In the prior art, in order to make a continuous skeletal porous polymer into a carbon material, the carbonization process is performed at 700° C. or higher, and when the activation process is performed at 900° C., the polymer structure is collapsed and the carbon structure is not maintained. In addition, it was impossible to form pores at the micrometer level, which is advantageous for charge mobility.

In order to solve this problem, the present invention provides a method for producing a continuous skeletal porous carbon material in which the structure of the epoxy resin does not collapse in the carbonization and activation process by adding nano-carbon to the epoxy resin, and binary pores manufactured according to the method To provide a continuous skeletal porous carbon material with

In order to solve the above problem,

The present invention in one embodiment, mixing an epoxy resin and nano-carbon to form a carbon precursor; preparing a continuous skeletal porous carbon material precursor by adding a pore former to the carbon precursor; carbonizing the continuous skeletal porous carbon material precursor by a first heat treatment; and an activation step of introducing nano-sized pores by performing a second heat treatment after the carbonization.

The content of the nano-carbon relative to the total content of the epoxy resin may be 1 to 5 wt%.

The nano-carbon may include one or more selected from the group consisting of graphene, carbon nanotubes, and carbon nanofibers.

The pore former may include a thermoplastic resin.

The preparing of the continuous skeletal porous carbon material precursor may include adding a pore former to the carbon precursor and heat curing by heating; and removing the pore former.

The first heat treatment step may be to heat to 700 to 1,000 °C at a temperature increase rate of 0.5 to 10 °C / min, and then to maintain for 30 to 80 minutes.

The second heat treatment step may be heated to 800 to 1,000 °C at a temperature increase rate of 5 to 20 °C/min and then maintained for 10 to 50 minutes.

In addition, in one embodiment, the present invention has a continuous skeleton comprising an epoxy resin and nano-carbon, and a plurality of first pores having a pore size of 1 to 10 nm in the continuous skeleton; and a continuous skeletal porous carbon material including a plurality of second pores having a pore size of 10 to 100 μm.

The content of the nano-carbon relative to the total content of the epoxy resin may be 1 to 5 wt%.

The method for producing a continuous skeletal porous carbon material according to the present invention is a continuous skeletal porous carbon material in which the structure of the epoxy resin is not collapsed and nanometer-level pores are introduced in the carbonization process at 700° C. or higher and the activation process at 900° C. or higher by adding nano-carbon to the epoxy resin. A skeletal porous carbon material can be produced.

In addition, the continuous skeletal porous carbon material prepared according to the above manufacturing method can improve electrical conductivity by adding nano-carbon and continuous skeleton, and by having binary pores of several to tens of μm and several nm, charge mobility and It is possible to increase the charge storage capacity.

1 is a schematic view showing a method for producing a continuous skeletal porous carbon material according to the present invention.
2 is a scanning electron microscope image according to the curing temperature during the preparation of the continuous skeletal porous carbon material precursor according to the embodiment of the present invention.
3 is a scanning electron microscope image of a continuous skeletal porous carbon material and commercially available activated carbon to which 0, 1, and 3 wt% of graphene is added in an embodiment of the present invention.
4 is a transmission electron microscope image of a continuous skeletal porous carbon material to which 1 wt% of graphene is added according to an embodiment of the present invention.
5 is a graph showing the pore distribution of the continuous skeletal porous carbon material and commercially available activated carbon to which 0, 1, and 3 wt% of graphene is added in an embodiment of the present invention.
6 is a graph showing the specific capacitance measurement results for current densities from 0 to 10 A/g of continuous skeletal porous carbon material and commercially available activated carbon to which 0, 1, and 3 wt% of graphene is added in an embodiment of the present invention; it has been shown

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail in the detailed description.

However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

In the present invention, terms such as "comprises" or "have" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one or more other features It is to be understood that this does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

The present invention prepares a continuous skeletal porous carbon material precursor by using the phase separation phenomenon of an epoxy resin to which nano-carbon is added and a pore former, and then through carbonization and activation processes to produce a binary-based pore-structured carbon material having a continuous skeleton. can

The carbon material according to the conventional method of manufacturing a carbon material using an epoxy resin has a problem in that the structure is not continuously connected and thus electrical conductivity is lowered, but the present invention can improve this problem. In addition, it is possible to show high efficiency when applying a supercapacitor by manufacturing a novel binary pore carbon material in which pores at the level of several to tens of μm and several nm are simultaneously formed inside the continuous skeleton.

Hereinafter, the present invention will be described in detail.

The present invention comprises the steps of forming a carbon precursor by mixing an epoxy resin and nano-carbon; preparing a continuous skeletal porous carbon material precursor by adding a pore former to the carbon precursor; carbonizing the continuous skeletal porous carbon material precursor by a first heat treatment; and an activation step of introducing nano-sized pores by performing a second heat treatment after the carbonization.

The method for producing a continuous skeletal porous carbon material according to the present invention is a continuous skeletal porous carbon material in which the structure of the epoxy resin is not collapsed and nanometer-level pores are introduced in the carbonization process at 700° C. or higher and the activation process at 900° C. or higher by adding nano-carbon to the epoxy resin. A skeletal porous carbon material can be produced.

1 is a schematic view showing a method for producing a continuous skeletal porous carbon material according to the present invention.

Referring to FIG. 1 , in the method of manufacturing the continuous skeletal porous carbon material, first, an epoxy resin and nano-carbon are mixed to form a carbon precursor. In this case, acetone may be added and mixed as a solvent, and the acetone may be removed by heating.

The content of the nano-carbon relative to the total content of the epoxy resin may be 1 to 5 wt%. For example, the content of the nano-carbon relative to the total content of the epoxy resin may be 1 to 4 wt%, 1 to 3 wt%, 1 to 2 wt%, 2 to 5 wt%, or 2 to 3 wt%.

The nano-carbon may include one or more selected from the group consisting of graphene, carbon nanotubes, and carbon nanofibers. For example, the nano-carbon may be graphene.

After the carbon precursor is formed, a pore former is added to the carbon precursor. When the pore former is added, a curing agent for curing the epoxy resin may be added.

The carbon precursor and the pore former are phase-separated using a phase-separation phenomenon that occurs when two or more types of polymers are mixed due to the high molecular weight of the polymer, and then heat-cured only the epoxy resin of the carbon precursor by heating. At this time, only the epoxy resin is thermally cured by the curing agent, the nano-carbon is dispersed in the cured epoxy resin, and the pore former may exist without being cured and phase-separated.

The heating may be heating at 80 to 200 ℃ for 1 to 3 hours. For example, the heating may be heating at 100 to 180 ℃ or 170 ℃.

After the thermosetting, the pore former is removed by ultrasonic treatment in ultrapure water to prepare a continuous skeletal porous carbon material precursor. Since the pore former is not hardened and is readily soluble in water during thermal curing, voids may be formed at the location of the pore former by dissolving it in ultrapure water.

As the mole fraction of the pore former increases compared to the epoxy resin, a larger portion is removed when the pore former is removed, thereby increasing the size of the pores. Therefore, pore control can be performed according to the mole fraction of the pore former compared to the epoxy resin.

The pore former may include a thermoplastic resin. Since the pore former is a material to be removed by dissolving it in water, it may be a water-soluble thermoplastic resin, for example, the pore former may be polyethylene glycol (PEG).

Before carbonizing the continuous skeletal porous carbon material precursor, in order to increase the thermal stability of the precursor, a stabilization process may be performed for 10 to 50 minutes at 300 to 350° C. in an air atmosphere using a tubular electric furnace. For example, the stabilization process may be performed at 310 to 330°C or 320°C for 20 to 40 minutes or 30 minutes.

After the stabilization process, the continuous skeletal porous carbon material precursor may be carbonized by a first heat treatment to prepare a continuous skeletal porous carbon material. In order to prevent the continuous skeleton from collapsing by heat, the first heat treatment step may be to heat from the stabilization process temperature to 700 to 1,000 °C at a temperature increase rate of 0.5 to 10 °C/min, and then hold for 30 to 80 minutes. have. For example, the first heat treatment step is 0.5 to 5 °C/min, 0.5 to 3 °C/min, 0.5 to 1 °C/min, 1 to 10 °C/min, 1 to 5 °C/min, or 1 to 2 °C/min. It can be heated to 700 to 900 ° C, 700 to 800 ° C, 700 to 750 ° C, 800 to 1,000 ° C, 800 to 900 ° C, 750 to 800 ° C or 700 ° C at a temperature increase rate of min, and 30 to 60 minutes after heating , 30 to 50 minutes, 50 to 80 minutes, 50 to 70 minutes, or may be maintained for 60 minutes.

The continuous skeleton porous carbon material may maintain a continuous skeleton and porous structure by nano-carbon even after the carbonization process at 700° C. or higher, and may include pores at a level of several to tens of μm in the continuous skeleton.

The carbonization may be performed in an inert gas atmosphere.

After the sample is removed from the carbonization electric furnace after carbonization, an activation process of introducing nano-sized pores is performed by subjecting the continuous skeletal porous carbon material to a second heat treatment in an activation process furnace using water vapor. The second heat treatment step may be heated to 800 to 1,000 °C at a temperature increase rate of 5 to 20 °C/min and then maintained for 10 to 50 minutes. For example, the second heat treatment step may be performed at a rate of 5 to 15 °C/min, 5 to 10 °C/min, 10 to 20 °C/min, 15 to 20 °C/min, 8 to 15 °C/min, or 10 °C/min. It can be heated to 800 to 900°C, 850 to 1,000°C, 850 to 950°C or 900°C at a temperature increase rate, and after heating, 10 to 50 minutes, 10 to 40 minutes, 10 to 30 minutes, 20 to 60 minutes, 20 It may be maintained for 40 minutes or 30 minutes.

The continuous skeleton porous carbon material can maintain a continuous skeleton and porous structure even after the activation process at 900° C. or higher, and pores of several nm level are introduced through the activation process, so that several to tens of μm and several nm in the continuous skeleton It is possible to prepare a continuous skeleton & binary porous carbon material containing a level of binary pores.

The present invention also provides a continuous skeletal porous carbon material produced according to the method for producing a continuous skeletal porous carbon material. The continuous skeleton porous carbon material has a continuous skeleton comprising an epoxy resin and nano-carbon, and a plurality of first pores having a pore size of 1 to 10 nm in the continuous skeleton; and a plurality of second pores having a pore size of 10 to 100 μm.

The content of the nano-carbon relative to the total content of the epoxy resin may be 1 to 5 wt%. For example, the content of the nano-carbon relative to the total content of the epoxy resin may be 1 to 4 wt%, 1 to 3 wt%, 1 to 2 wt%, 2 to 5 wt%, or 2 to 3 wt%.

The nano-carbon may include one or more selected from the group consisting of graphene, carbon nanotubes, and carbon nanofibers. For example, the nano-carbon may be graphene.

The continuous skeletal porous carbon material can improve electrical conductivity by adding nano-carbon and continuous skeletal structure, and can increase charge mobility and charge storage capacity by having binary pores of several to tens of μm and several nm. have.

Hereinafter, the present invention will be described in more detail through Examples and the like according to the present invention, but the scope of the present invention is not limited by the Examples presented below.

[Example]

Preparation Example: Preparation of continuous skeletal porous carbon material

Epoxy resin [Bisphenol A diglycidyl ether] 340.42 g/mol, Epoxy resin curing agent [bis(4-aminocyclohexyl)methane] 210.37 g/mol, 200 g/mol of a pore former [polyethylene glycol] and multilayer graphene powder (average thickness: 5 nm, average particle size: 11 µm) were used as raw materials. Epoxy resins and epoxy resin curing agents are used to make carbon precursors with a continuous skeleton through a thermal curing process, and pore formers are used to prepare continuous pores through spinodal decomposition. Graphene is added to a mixture of an epoxy resin and an epoxy resin curing agent to contribute to the thermal stability of the continuous skeleton and is used for increasing electrical conductivity. The continuous skeletal porous carbon material is produced by the following three-step manufacturing process.

1) Preparation of continuous skeletal porous carbon material precursor

0 (no graphene added), 1, 3 wt% of graphene powder and 30 wt% of acetone were added to the epoxy resin, respectively, mixed using a blade mill, and then heated at 100° C. to remove the acetone (materials A). 0.5 g of a curing agent and 3.5 g of a pore forming agent were added to 1 g of Material A, mixed through ultrasonication, and then heat-cured by heating at 170° C. for 2 hours (Material B). To remove the pore former inside the material B, the material B was placed in ultrapure water and ultrasonicated for 2 hours to remove the pore former to prepare a continuous skeletal porous carbon material precursor.

2) Carbonization process

Before carbonization, in order to increase the thermal stability of the precursor, a stabilization process was performed at 320° C. for 30 minutes in an air atmosphere using a tubular electric furnace. Thereafter, heat treatment was performed at 700° C. for 1 hour in a nitrogen atmosphere. In order to prevent the continuous skeleton from collapsing by heat, the heat treatment was carried out as slowly as possible at a rate of 1° C./min.

3) Activation process

A continuous skeletal porous carbon material was prepared by activating at 900° C. for 30 minutes using water vapor to introduce nano-sized pores. The temperature increase rate was set at 10°C/min.

Experimental Example 1: Precursor shape experiment according to thermosetting temperature

The image according to the thermosetting temperature of the prepared continuous skeletal porous carbon material precursor is shown in FIG. 2 .

As shown in Figure 2, when the curing temperature is 80 ℃, Connected globule structures, 110 ℃, Connected macropore structures (pore size 5 ㎛ or more), At 140 ℃, Connected macropore structures (pore size 2 ㎛ or more), and 170 At ℃, 3D skeletal network structures were shown. Accordingly, it was found that the shape of the precursor could be controlled according to the curing temperature.

Experimental Example 2: Characterization of continuous skeletal porous carbon material

3 is a scanning electron microscope image of the continuous skeletal porous carbon material and commercially available activated carbon to which 0, 1, and 3 wt% of the prepared graphene is added.

As shown in FIG. 3 , it was found that the continuous skeleton porous carbon material according to the present embodiment forms a continuous skeleton, compared to the shape of commercially available activated carbon in powder form. In the graphene 0 wt% sample without the addition of graphene, the structure collapses during the carbonization process and a partially continuous skeleton is formed. It can be confirmed that the pores are small, and it can be confirmed that the 3 wt% graphene sample maintains a continuous skeletal structure.

4 shows a transmission electron microscope image of the continuous skeletal porous carbon material to which 1 wt% of graphene of this example is added.

As shown in FIG. 4 , it can be seen that graphene is introduced into the carbon skeleton, and it can be seen that nanopores of several nm level are developed by the activation process.

5 is a graph showing the pore distribution diagram of the continuous skeletal porous carbon material and commercially available activated carbon added with 0, 1, and 3 wt% of graphene of this example.

As shown in FIG. 5 , the nanopores of the commercially available activated carbon were concentrated in the size of 1 to 2 nm, whereas the nanopores of the continuous skeletal porous carbon material increased in size to the level of 2 to 3 nm.

Table 1 below shows the measured pore characteristics of each sample. The specific surface area of the commercially available activated carbon was higher than that of the continuous skeletal porous carbon material except for the graphene 1 wt% sample, and the pore volume of the commercially available activated carbon was also larger.

6 shows the specific capacitance measurement results for current densities from 0 to 10 A/g of the continuous skeletal porous carbon material and commercially available activated carbon to which 0, 1, and 3 wt% of graphene of this example were added.

As shown in FIG. 6 , although the specific surface area and pore volume of the commercially available activated carbon were larger (see Table 1), the polymer phase separation-based carbon material showed a specific capacitance increase of about 30% compared to the commercially available activated carbon for the entire area. showed This is considered to be indicated by the increase in electrical conductivity due to the addition of graphene and the continuous skeleton, and the increase in charge mobility due to the introduction of pores of several to tens of μm.

Claims (9)

mixing an epoxy resin and nano-carbon to form a carbon precursor;
preparing a continuous skeletal porous carbon material precursor by adding a pore former to the carbon precursor;
carbonizing the continuous skeletal porous carbon material precursor by a first heat treatment; and,
A method for producing a continuous skeletal porous carbon material comprising an activation step of introducing nano-sized pores by performing a second heat treatment after the carbonization.
The method of claim 1,
The method for producing a continuous skeletal porous carbon material, characterized in that the content of the nano-carbon relative to the total content of the epoxy resin is 1 to 5 wt%.
The method of claim 1,
The nano-carbon is a method for producing a continuous skeletal porous carbon material, characterized in that it comprises at least one selected from the group consisting of graphene, carbon nanotubes and carbon nanofibers.
The method of claim 1,
The method for producing a continuous skeletal porous carbon material, characterized in that the pore former comprises a thermoplastic resin.
The method of claim 1,
The step of preparing the continuous skeletal porous carbon material precursor,
thermosetting by adding a pore former to the carbon precursor and heating; and
Method for producing a continuous skeletal porous carbon material, characterized in that it further comprises the step of removing the pore former.
The method of claim 1,
The first heat treatment step is a method for producing a continuous skeletal porous carbon material, characterized in that after heating to 700 to 1,000 ℃ at a temperature increase rate of 0.5 to 10 ℃ / min and maintained for 30 to 80 minutes.
The method of claim 1,
The second heat treatment step is a method for producing a continuous skeletal porous carbon material, characterized in that after heating to 800 to 1,000 ℃ at a temperature increase rate of 5 to 20 ℃ / min and then maintained for 10 to 50 minutes.
It has a continuous skeleton comprising an epoxy resin and nano-carbon,
a plurality of first pores having a pore size of 1 to 10 nm in the continuous framework; and
A continuous skeletal porous carbon material comprising a plurality of second pores having a pore size of 10 to 100 μm.
9. The method of claim 8,
The continuous skeletal porous carbon material, characterized in that the content of the nano-carbon relative to the total content of the epoxy resin is 1 to 5 wt%.

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