KR20150094503A - Crystallized carbon structure, method for fabricating the same, and energy storage device having the same - Google Patents

Abstract

Provided are a crystalline carbon structure, a manufacturing method thereof, and an energy storage device comprising the same. Regarding a manufacturing method of a crystalline carbon structure, provided is a reaction solution comprising an organic solvent containing an aromatic compound, and a catalyst. The crystalline carbon structure is formed by generating plasma inside the reaction solution.

Description

TECHNICAL FIELD The present invention relates to a crystalline carbon structure, a method of manufacturing the same, and an energy storage device containing the same.

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a carbon structure and an electrochemical device including the carbon structure, and more particularly, to an electrochemical energy storage device.

Carbon nanomaterials are emerging as next-generation materials because they exhibit high mechanical properties, excellent electrical properties and thermal properties by light weight and bonding method between carbon atoms. As a result, research results on various nanostructured carbon nanomaterials have been continuously disclosed.

Methods for synthesizing carbon nanomaterials include an electric discharge method, a laser deposition method, a plasma chemical vapor deposition method, a thermochemical vapor deposition method, and a vapor phase synthesis method. In order to synthesize carbon nanomaterial, three components of catalyst, high temperature reaction condition and hydrocarbon raw material are required. Generally, carbon nanomaterial is synthesized through high temperature pyrolysis of hydrocarbon raw material in the presence of metal catalyst.

For example, the conventional method of synthesizing carbon nanotubes, which is one of the carbon nanomaterials, can be classified as follows: a catalytic metal layer is formed by using an evaporator, a sputterer, or a metal organic chemical vapor Deposition method was used to form carbon nanotubes on the substrate.

Korean Patent Application No. 2003-93666 discloses a method for synthesizing carbon nanotubes by thermochemical vapor deposition. However, in the conventional method as described above, there is a disadvantage in that the time for raising the temperature of the reaction furnace from room temperature to the synthesis temperature after the charging of the substrate is considerably long, thereby increasing the processing time of the carbon nanotubes. Further, There is a drawback that metal charging is not possible.

Therefore, there is still a need for a synthesis method for producing a large amount of carbon nanomaterials in a simpler manner.

A problem to be solved by the present invention is to provide a crystalline carbon structure through a simpler method.

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

According to an aspect of the present invention, there is provided a method of manufacturing a carbon structure. There is provided a reaction liquid containing an organic solvent containing an aromatic compound and a catalyst. A plasma is generated in the reaction solution to form a crystalline carbon structure.

The aromatic compound may be benzene, biphenyl, naphthalene, anthracene, or a combination of two or more thereof.

The catalyst may be an organometallic compound, a sulfur-containing compound, or a combination thereof. The organometallic compound may be a metallocene. The metallocene may be ferrocene, nickelocene, cobaltocene, or ruthenocene. In the reaction solution, the metallocene may be contained in an amount of 1 to 10 parts by weight based on 100 parts by weight of the solvent. In the reaction solution, the metallocene may be contained in an amount of 2 to 10 parts by weight based on 100 parts by weight of the solvent. In the reaction solution, the metallocene may be contained in an amount of 5 to 10 parts by weight based on 100 parts by weight of the solvent.

The sulfur-containing compound may be selected from the group consisting of thiophene, dibenzothiophene, diphenyldisulfide, hydrogen sulfide, diallyl sulfide, allyl methyl sulfide, , Or a combination thereof. In the reaction solution, the sulfur-containing compound may be contained in an amount of 1 to 10 parts by weight based on 100 parts by weight of the solvent.

The reaction solution may further contain distilled water.

In the plasma discharge step, the temperature of the reaction liquid may be maintained at the boiling point of the aromatic compound.

According to another aspect of the present invention, there is provided a carbon structure. The carbon structure has straight-shaped crystal phase groups arranged in a plurality of different directions, and has pores therein. The carbon structure may be nanoparticles. The pores may be mesopores. A transition metal oxide, a sulfur oxide, or a combination thereof disposed on the surface or inside of the carbon structure.

According to another aspect of the present invention, there is provided an energy storage device. The energy reservoir has a first electrode, a second electrode, and a second electrode disposed between the first electrode and the second electrode, the first electrode having a linear structure of crystal phases arranged in a plurality of different directions and having a carbon structure having pores therein, Lt; / RTI > The carbon structure may be nanoparticles. The pores may be mesopores. A transition metal oxide, a sulfur oxide, or a combination thereof disposed on the surface or inside of the carbon structure.

1 is a flowchart illustrating a method of manufacturing a crystalline carbon structure according to an embodiment of the present invention.
2 is a schematic diagram illustrating an energy reservoir according to one embodiment of the present invention.
FIGS. 3 to 13 are TEM (transmission electron microscopy) photographs of carbon structures according to Production Examples 1 to 11, respectively.
14 is a TEM photograph of a carbon structure according to a comparative example.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms.

Method for producing crystalline carbon structure

1 is a flowchart illustrating a method of manufacturing a crystalline carbon structure according to an embodiment of the present invention.

Referring to FIG. 1, a reaction solution containing an organic solvent containing an aromatic compound and a catalyst is provided (S10).

The aromatic compound is an aromatic compound having 6 to 12 carbon atoms and may be a carbon precursor, that is, a raw material of crystalline carbon. In one example, the aromatic compound can be unsubstituted or substituted benzene, unsubstituted or substituted biphenyl, unsubstituted or substituted naphthalene, unsubstituted or substituted anthracene, or a combination of two or more thereof. The substituent may be a hydroxyl group, a methyl group, or a nitro group. As an example, the substituted benzene may be toluene, xylene, or nitrobenzene.

The catalyst may be an organometallic compound, a sulfur-containing compound, or a combination thereof. When the organometallic compound and the sulfur-containing compound are used together, the organometallic compound may be a catalyst and the sulfur-containing compound may be a daily promoter.

The organometallic compound may be at least one kind of metallocene. The metallocene can be, for example, ferrocene, nickelocene, cobaltocene, or ruthenocene, including transition metals such as Fe, Ni, Co, or Ru . The organometallic compound in the reaction solution is contained in an amount of 1 to 10 parts by weight, specifically 2 to 10 parts by weight, or 5 to 10 parts by weight, based on 100 parts by weight of the solvent, considering both crystallinity and economical efficiency .

The sulfur-containing compound may be selected from the group consisting of thiophene, dibenzothiophene, diphenyldisulfide, hydrogen sulfide, diallyl sulfide, allyl methyl sulfide, , Or a combination thereof. In the reaction solution, the sulfur-containing compound may be contained in an amount of 1 to 10 parts by weight, specifically 2 to 10 parts by weight, or 5 to 10 parts by weight, based on 100 parts by weight of the solvent.

On the other hand, distilled water may be added to the reaction solution. The distilled water may be contained in an amount of 100 to 1000 parts by weight, specifically 500 to 900 parts by weight, or 600 to 800 parts by weight, based on 100 parts by weight of the organic solvent.

Subsequently, a plasma is generated in the reaction solution to obtain a carbon structure (S20). At this time, the reaction solution may be stirred to be well mixed.

Specifically, plasma can be generated in the reaction liquid by immersing the plasma generating electrode and the ground electrode in the reaction liquid and applying a high voltage between the two electrodes to discharge the reaction liquid. At this time, a carbon structure may be produced by an oxidation and / or reduction reaction of an aromatic compound in the reaction solution. The conditions for the plasma generation may be that a voltage of 660 to 8250 V is applied at a frequency of 1 to 100 kHz, specifically 3 to 70 kHz and a pulse width of 1 to 10 mu s. The higher the frequency and voltage, the greater the plasma intensity and the faster the reaction rate. Thus, the production of carbon structures can be controlled by adjusting the frequency, voltage, and discharge time.

In addition, the reaction solution may not be cooled during the plasma discharge process. In other words, in the plasma discharge process, the temperature of the reaction liquid can be maintained near the boiling point of the aromatic compound. In this case, since the catalytic activity is increased, the crystallinity of the carbon structure can be improved.

In the plasma discharge process, the organometallic compound has a multi-layered crystal phase in which a carbon structure is at least partially laminated with multi-layered graphene layers such as graphite, or a linear crystal phase in which multi-layered graphene layers are linearly extended Can be done. Concretely, when the organometallic compound is contained in the reaction solution in an amount of 2 parts by weight or more based on 100 parts by weight of the solvent, such a multi-layered crystal phase or a linear crystal phase can predominantly appear in the carbon structure.

In addition, the sulfur-containing compound appears to serve as a cocatalyst for assisting the organometallic compound, and such a sulfur-containing compound can be obtained under the condition that the organometallic compound is contained in an amount of 5 parts by weight or more based on 100 parts by weight of the solvent , At least 6 parts by weight, at least 7 parts by weight, at least 8 parts by weight, at least 9 parts by weight, or at least 10 parts by weight of at least one catalyst component. Such mesopores are pores having diameters of 2 to 50 nm, specifically, 2 to 20 nm, and mesoporous carbon structures can be utilized in various electrochemical devices, particularly energy storage devices.

When distilled water is added to the reaction solution, the aromatic compound may be dispersed in the reaction solution. However, the oxygen functionality of the distilled water may react with the transition metal of the organometallic compound to react the transition metal oxide with the sulfur of the sulfur-containing compound to produce the sulfur oxides, or both.

Finally, the carbon structure thus produced can be separated from the organic solvent (S30). This separation can be performed using a filtering method.

Thereafter, the separated carbon structure can be cleaned and heat-treated (S40). The washing may be carried out using an aqueous solution in which water and a volatile solvent are mixed. However, the present invention is not limited to this, and the cleaning process may be omitted. The heat treatment step may be performed in an air atmosphere, and may be performed at 400 ° C to 500 ° C. If the heat treatment temperature is lower than 400 ° C, the organic solvent remaining on the surface of the carbon structure may not be removed. If the heat treatment temperature is higher than 500 ° C, carbon may be burned with carbon dioxide.

The crystalline carbon structure

The carbon structure produced as described above can be nanoparticles having a size of several to several hundred nanometers. The nanoparticles may be spherical particles having mesopores. In addition, the carbon structure may have a crystalline phase. In this case, the conductivity can be improved, and the conductivity can be greatly improved, especially when the crystal phase is a straight crystal phase or a multi-layered crystal phase such as graphite. The carbon structure may have a plurality of linear crystalline groups in one particle, and the directions of the linear crystalline groups may be different from each other. In this case, the linear crystal phase group means a unit group in which crystal faces, that is, graphene layers are laminated in parallel to each other, and the direction of the linear crystal phase group can mean a direction in which the crystal face extends.

Further, the carbon structure may have a plurality of pores therein. These pores may be mesopores, that is, pores having a size of 2 to 50 nm, and specifically may have a diameter of 2 to 20 nm. In addition, a transition metal oxide formed by oxidizing an organic metal compound such as iron oxide, nickel oxide, cobalt oxide, ruthenium oxide, or a combination of two or more thereof, sulfur oxide, or transition metal oxide Both the persulfates may be disposed.

Energy storage element

2 is a schematic diagram illustrating an energy reservoir according to one embodiment of the present invention.

In this embodiment, the energy reservoir may be an electrochemical energy storage element, an electrochemical capacitor or a secondary battery. The electrochemical capacitor may be a supercapacitor or a lithium ion capacitor. The secondary battery may be a lithium secondary battery, a sodium secondary battery, or a lithium air battery. However, the present invention is not limited thereto.

Hereinafter, a lithium-ion battery will be described as an example.

Referring to FIG. 2, the positive electrode active material layer 120, the negative electrode active material layer 140, and the separator 130 interposed therebetween. The electrolyte 160 may be disposed or filled between the cathode active material layer 120 and the separator 130 and between the anode active material layer 140 and the separator 130. The positive electrode active material layer 120 may be disposed on the positive electrode collector 110 and the negative electrode active material layer 140 may be disposed on the negative electrode collector 150.

The anode including the cathode active material layer 120 and the cathode current collector 110 may also be referred to as an air electrode. The anode current collector 110 can use a mesh or mesh-like porous body for accelerating the diffusion of oxygen. For example, carbon paper coated with a porous metal plate such as iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold or platinum or carbon paste can be used. However, the present invention is not limited thereto and can be used as long as it can be used as a current collector in the art. Also, the cathode current collector 110 may be coated with a metal or an alloy coating with oxidation resistance.

The cathode active material layer 120 may include a carbon structure formed according to the manufacturing method described with reference to FIG. In particular, when the carbon structure has a crystal phase, the conductivity can be improved, and in particular, when the crystal phase is linear, the conductivity can be greatly improved. Further, in the case where the carbon structure has a plurality of pores therein, such pores can also be used as a delivery path of oxygen in a lithium air cell, so that the cell capacity can be greatly improved.

The cathode active material layer 120 may further include a redox catalyst of oxygen in addition to the carbon structure. The oxidation-reduction catalyst of oxygen may be a transition metal oxide. In one embodiment, the transition metal oxide is selected from the group consisting of SnO ₂ , MnO, MnO ₂ , Mn ₂ O ₃ , RuO ₂ , FeO, Fe ₂ O ₃ , Fe ₃ O ₄ , NiO, Co ₃ O ₄ , More than one can be selected. In the carbon structure production example described above with reference to FIG. 1, when distilled water is added to the reaction solution, a carbon structure containing a transition metal oxide can be prepared, and a transition metal oxide is not added to the carbon structure This can be.

The positive electrode active material layer 120 may further include a binder to facilitate fixing to the positive electrode current collector 110. The binder may be variously selected from polyvinyl alcohol, diacetyl cellulose, polyethylene, polypropylene, epoxy resin and the like.

The anode active material layer 140 and the anode current collector 150 may constitute a cathode. The anode active material layer 140 may be lithium or a lithium alloy. In the case of a lithium alloy, it may be an alloy of lithium and at least one metal selected from the group consisting of aluminum, tin, magnesium, indium, and calcium. The anode current collector 150 may be made of a metal having heat resistance, for example, iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum and the like.

The separator 130 may be a film laminate containing polyethylene or polypropylene as an insulating porous body, or a fibrous nonwoven fabric containing cellulose, polyester, or polypropylene.

The electrolyte 160 may be an aqueous or non-aqueous electrolytic solution, but a non-aqueous electrolytic solution is preferred to increase the operating voltage of the device. However, the electrolyte 160 is not limited thereto, and may be a solid electrolyte. The non-aqueous electrolyte solution includes an electrolyte and a medium, and the electrolyte may be a lithium salt, a copper salt, or an ammonium salt. The lithium salt is selected from the group consisting of lithium perchlorate (LiClO ₄ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium trifluoromethane sulfonate (LiCF ₃ SO ₃ ), lithium hexafluoroacetate _6), or lithium trifluoromethanesulfonate sulfonyl imide _{(Li (CF 3 SO 2)} 2 N) may be. The copper salt may be copper (I) thiocyanate, copper (II) triflate, or the like. Ammonium salts include tetraethylammonium tetrafluoroborate (TEABF ₄ ), triethylmonomethylammonium tetrafluoroborate, tetraethylammonium hexafluorophosphate, N, N-diethyl-N-methyl- Ethyl) ammonium (DEME) salt. The medium is ethylene carbonate, propylene carbonate. Dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, acrylonitrile or? -Caprolactone.

Hereinafter, exemplary embodiments of the present invention will be described in order to facilitate understanding of the present invention. It should be understood, however, that the following examples are intended to aid in the understanding of the present invention and are not intended to limit the scope of the present invention.

≪ Preparation Examples 1 to 9: Preparation of carbon structure >

As a solvent, 100 parts by weight (355 g) of benzene was mixed with ferrocene and / or thiophene in an amount shown in Table 1 as a catalyst to prepare a reaction solution. Thereafter, the plasma was discharged in the reaction solution. The electrode for plasma generation was a tungsten rod material having a diameter of 2.6 mm. The distance between the electrodes was fixed to 0.5 mm using a thickness gauge. For the generation of the plasma, the power source was discharged at a frequency of 30 kHz, a pulse width of 5 s, and a voltage of 8250 V, respectively. Stirring was performed to uniformly maintain the concentration distribution in the reaction solution during discharging, and the solution was not allowed to cool. As the plasma discharge progressed, the color of benzene rapidly changed to black in the reaction solution, and black carbon structures were synthesized.

After the plasma discharge was completed, the resulting carbon structure was filtered and separated, and then dried in an oven at 80 DEG C for 24 hours in an air atmosphere. The dried carbon structure was heat-treated at 450 ° C for 20 minutes.

≪ Preparation Example 10: Preparation of carbon structure >

A carbon structure was prepared in the same manner as in Preparation Example 1 except that 700 parts by weight (860 g) of distilled water, 10 parts by weight of ferrocene and 10 parts by weight of thiophene were mixed with 100 parts by weight (123 g) of benzene to prepare a reaction solution.

≪ Preparation Example 11: Preparation of carbon structure >

A carbon structure was prepared in the same manner as in Preparation Example 1 except that 100 parts by weight (123 g) of benzene and 700 parts by weight (860 g) of distilled water were mixed to prepare a reaction solution.

≪ Comparative Example: Carbon Structure Production >

A carbon structure was prepared in the same manner as in Preparation Example 1 except that a reaction solution containing only 355 g of benzene was prepared.

benzene
(Parts by weight,
(Actual weight)) Ferrocene
(Parts by weight,
(Actual weight)) Thiophene
(Parts by weight,
(Actual weight)) Distilled water
(Parts by weight,
(Actual weight)) Production Example 1 100
(355 g) 1 (3.55 g) - - Production Example 2 1 (3.55 g) 1 (3.55 g) - Production Example 3 2 (7.1 g) 2 (7.1 g) - Production Example 4 5 (17.75 g) - - Production Example 5 5 (17.75 g) 1 (3.55 g) - Production Example 6 5 (17.75 g) 5 (17.75 g) - Production Example 7 5 (17.75 g) 10 (35.5 g) - Production Example 8 10 (35.5 g) 10 (35.5 g) - Production Example 9 - 1 (3.55 g) - Production Example 10 100
(123g) 10 (12.3 g) 10 (12.3 g) 700 (860 g) Production Example 11 - - 700 (860 g) Comparative Example 355g - - -

FIGS. 3 to 13 are TEM (transmission electron microscopy) photographs of carbon structures according to Production Examples 1 to 11, respectively. 14 is a TEM photograph of a carbon structure according to a comparative example.

Referring to FIGS. 3 to 12, carbon structures obtained by generating a plasma in a reaction solution containing benzene as an aromatic compound and a catalyst all have a crystalline phase. Meanwhile, referring to FIG. 14, carbon structures obtained by generating plasma in a reaction solution containing only benzene as an aromatic compound without adding a catalyst showed an amorphous phase.

In the case of using carbon structures according to Production Example 11 (FIG. 13) and Production Example 9 (FIG. 11), that is, no catalyst was used (Production Example 11) or only thiophene It can be seen that it shows a curved crystal phase.

However, when carbon structures according to Production Examples 1 to 8 (Figs. 3 to 10), that is, ferrocene, which is an organometallic compound, is used as a catalyst, it can be seen that a linear crystalline phase appears at least partially. In addition, it can be seen that, when carbon structures according to Production Examples 3 to 8 (FIGS. 5 to 10), that is, ferrocene, which is an organometallic compound as a catalyst, is used in an amount of 2 parts by weight or more, a straight crystal phase is predominant.

In particular, 10 parts by weight of thiophene, which is a sulfur-containing compound, was used as a cocatalyst while using 5 parts by weight or more of carbon structures according to Production Examples 7 and 8 (FIGS. 9 and 10) When used, it can be seen that mesopores (a) having pores specifically between 2 and 50 nm in diameter are formed in the carbon structures. Also, it can be seen that the carbon structures are spherical particles (b) having mesopores.

On the other hand, 10 parts by weight of carbon structures according to Production Example 10 (Fig. 12), namely, ferrocene as an organometallic compound as a catalyst, 10 parts by weight of thiophene as a sulfur-containing compound as a cocatalyst, Even in the case of submixing, it can be seen that a linear crystal phase is predominant and a mesopore (a) having a pore diameter of 2 to 50 nm is formed inside the carbon structures. However, it was understood that a large number of portions determined to be iron oxide or sulfur oxide appeared because the iron component in ferrocine or the sulfur component in thiophene was oxidized when distilled water was oxidized during the plasma discharge. However, it is not limited to these theories.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, This is possible.

Claims (20)

Providing a reaction liquid containing an organic solvent containing an aromatic compound and a catalyst; And
And generating a plasma in the reaction liquid to form a crystalline carbon structure. The method according to claim 1,
Wherein the aromatic compound is benzene, biphenyl, naphthalene, anthracene, or a combination of two or more thereof. The method according to claim 1,
Wherein the catalyst is an organometallic compound, a sulfur-containing compound, or a combination thereof. The method of claim 3,
Wherein the organometallic compound is a metallocene. 5. The method of claim 4,
Wherein the metallocene is selected from the group consisting of ferrocene, nickelocene, cobaltocene, and ruthenocene. 5. The method of claim 4,
Wherein the metallocene is contained in the reaction solution in an amount of 1 to 10 parts by weight based on 100 parts by weight of the solvent. The method according to claim 6,
Wherein the metallocene is contained in the reaction solution in an amount of 2 to 10 parts by weight based on 100 parts by weight of the solvent. 8. The method of claim 7,
Wherein the metallocene is contained in the reaction solution in an amount of 5 to 10 parts by weight based on 100 parts by weight of the solvent. The method of claim 3,
The sulfur-containing compound may be selected from the group consisting of thiophene, dibenzothiophene, diphenyldisulfide, hydrogen sulfide, diallyl sulfide, allyl methyl sulfide, , Or a combination thereof. 10. The method of claim 9,
Wherein the sulfur-containing compound is contained in the reaction solution in an amount of 1 to 10 parts by weight based on 100 parts by weight of the solvent. The method according to claim 1,
Wherein the reaction solution further comprises distilled water. The method according to claim 1,
Wherein the temperature of the reaction liquid in the plasma discharge step is maintained at a boiling point of the aromatic compound. A carbon structure having linear crystal phase groups arranged in a plurality of different directions and having pores therein. 14. The method of claim 13,
Wherein the carbon structure is a nanoparticle. 14. The method of claim 13,
Wherein the pores are mesopores. 14. The method of claim 13,
Wherein the carbon structure further comprises a transition metal oxide, a sulfur oxide, or a combination thereof disposed on or in the surface of the carbon structure. A first electrode having a linear structure of crystal groups arranged in a plurality of different directions and having a carbon structure having pores therein;
A second electrode; And
And an electrolyte disposed between the first electrode and the second electrode. 18. The method of claim 17,
Wherein the carbon structure is nanoparticles. 18. The method of claim 17,
Wherein the pores are mesopores. 18. The method of claim 17,
Further comprising a transition metal oxide, a sulfur oxide, or a combination thereof disposed on or in the surface of the carbon structure.

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