KR20170142425A - Metal oxide-coated carbon nanotube composite particle and preparing method of the same - Google Patents

Abstract

The present invention relates to an electrode material having a composite particle, a method of manufacturing a metal oxide-coated carbon nanotube composite particle, and a metal oxide-coated carbon nanotube composite particle comprising a carbon nanotube particle where carbon nanotubes formed by a rapid heat injection drying method are concentrated.

Description

METAL OXIDE-COATED CARBON NANOTUBE COMPOSITE PARTICLES AND METHOD FOR MANUFACTURING METAL OXIDE-COATED CARBON NANOTUBE COMPOSITE PARTICLE AND PREPARING METHOD OF THE SAME

The present invention relates to metal oxide-coated carbon nanotube composite particles comprising carbon nanotube particles in which carbon nanotubes are densely formed by rapid thermal spray drying, a method for producing the metal oxide-coated carbon nanotube composite particles, To electrode materials comprising composite particles.

Recently, energy storage materials are being studied in order to improve the output characteristics of secondary batteries and apply them to hybrid vehicles or to utilize high output capacitors as auxiliary output devices to improve fuel efficiency. A secondary battery for an automobile refers to a nickel-metal hydride battery and a lithium battery that can be charged and discharged. A super capacitor (ultra-high capacity capacitor) means a capacitor having a capacity of about 1,000 times higher than that of a conventional electrostatic capacitor.

Among ultra-high capacity capacitors, electrochemical capacitors based on electrochemical principles are classified into electric double layer capacitors (EDLC) and electrochemical Faraday reaction (pseudocapacitor) that exhibits a super-capacity of about 10 times higher than that of the EDLC type due to the pseudocapacitance generated in the faradaic reation.

In the case of the EDLC, a high-density charge is accumulated in the electric double layer by using activated carbon / fiber as an electrode active material of a capacitor, and it is widely used in fields requiring high output energy characteristics.

On the other hand, a pseudo capacitor having a relatively large capacity uses a metal oxide as an electrode active material, and much research has been conducted as an alternative to improve the capacitance characteristics of a conventional low capacity capacitor. Due to such high capacity and high output density characteristics, the pseudo capacitor can be used for a power source for an electric vehicle, a power source for portable mobile communication devices, a memory back-up power source for a computer, a power source for military / aerospace equipment, May be used alone or in combination with a secondary battery.

The most important material in the pseudo capacitor composed of the metal oxide electrode, the separator, the electrolyte, the current collector, the case and the terminal is the metal oxide based electrode material. As the metal oxide-based electrode material for pseudo-capacitors reported by domestic and foreign researchers, RuO ₂ , IrO ₂ , NiO _x , CoO _x , and MnO ₂ can be cited. Among the electrode materials, RuO ₂ has the highest storage capacity (720 F / g) in comparison with other electrode materials, but its applications are restricted to aerospace and military applications due to expensive raw materials.

The current high price of the study on the development of metal oxide nano-sized to much research on the electrode materials to replace the RuO ₂ to maximize the electrochemical utilization of domestic and has been progressing steadily in the United States and Japan, in particular, metal oxides It is actively proceeding.

Korean Patent Laid-Open Publication No. 2014-0028449 discloses a method for preparing spherical carbon particles by adding a carbon precursor aqueous solution to an organic solvent and stirring to form a water-in-oil emulsion and then heat-treating the carbon precursor aqueous solution. . However, when the carbon particles are used as an electrode material for a supercapacitor, they have a disadvantage that they have a low capacity.

The present invention relates to metal oxide-coated carbon nanotube composite particles comprising carbon nanotube particles in which carbon nanotubes are densely formed by rapid thermal spray drying, a method for producing the metal oxide-coated carbon nanotube composite particles, And to provide an electrode material comprising the composite particles.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

According to a first aspect of the present invention, there is provided a method of manufacturing a carbon nanotube dispersion, comprising: spraying and drying a dispersion of carbon nanotubes by a rapid thermal spray drying method to form carbon nanotube particles having dense carbon nanotubes; And coating a metal oxide on the dense carbon nanotube particles. The present invention also provides a method for producing a metal oxide-coated carbon nanotube composite particle.

The second aspect of the present invention provides a metal oxide-coated carbon nanotube composite particle comprising carbon nanotube-dense particles and a metal oxide coated on the particles.

A third aspect of the present invention provides an electrode material comprising metal oxide-coated carbon nanotube composite particles according to the second aspect of the present invention.

In one embodiment of the present invention, the spherical carbon nanotube particles are densely packed by spraying and drying by a rapid thermal spray drying method using a spray dryer, and then a metal oxide precursor and an acid are added and reacted (heat treated) A method for producing coated carbon nanotube composite particles, and metal oxide-coated carbon nanotube composite particles.

The metal oxide-coated carbon nanotube composite particles according to an embodiment of the present invention can be produced by a simple method of producing a spherical carbon nanotube particle by a rapid thermal spray drying method using a spray dryer, The metal oxide can be coated on the surface of the nanotube and the metal oxide exhibits a similar capacitor effect to improve the total capacitance. Therefore, it is possible to manufacture an electrode material for a supercapacitor having an electrochemical performance superior to that of a conventional super capacitor have. Also, the mass ratio of the carbon nanotubes to the metal oxide, the thickness of the coating, and the structure can be controlled by controlling the ratio of the metal oxide precursor used for coating the metal oxide.

In addition, when a metal oxide-coated carbon nanotube composite particle according to an embodiment of the present invention is applied to an electrode material for a supercapacitor, it is possible to manufacture an electrode for a supercapacitor having an excellent capacity characteristic, an improved rate- have.

FIG. 1 is a graph showing the results of comparison between spherical densely packed carbon nanotube particles (Comparative Example 1) and manganese oxide-coated carbon nanotube composite particles (Examples 1 and 2) according to manganese oxide coating amount in Comparative Examples and one embodiment of the present invention. Low magnification and high magnification electron microscope images.
FIGS. 2 (a) to 2 (d) show results of performing an energy dispersive spectroscopy (EDS) mapping analysis of manganese oxide-coated carbon nanotube composite particles according to an embodiment of the present invention.
FIG. 3 shows cyclic voltammetry measurement results of manganese oxide-coated carbon nanotube composite particles according to Comparative Examples and one embodiment of the present invention.
FIG. 4 is a graph showing a galvanostatic charge / discharge measurement result of a manganese oxide-coated carbon nanotube composite particle according to a comparative example and an embodiment of the present invention.
FIG. 5 shows the results of evaluation of life characteristics of manganese oxide-coated carbon nanotube composite particles according to Comparative Examples and one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It should be understood, however, that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, the same reference numbers are used throughout the specification to refer to the same or like parts.

Throughout this specification, when a part is referred to as being "connected" to another part, it is not limited to a case where it is "directly connected" but also includes the case where it is "electrically connected" do.

Throughout this specification, when a member is " on " another member, it includes not only when the member is in contact with the other member, but also when there is another member between the two members.

Throughout this specification, when an element is referred to as " including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise. The terms " about ", " substantially ", etc. used to the extent that they are used throughout the specification are intended to be taken to mean the approximation of the manufacturing and material tolerances inherent in the stated sense, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure. The word " step (or step) " or " step " used to the extent that it is used throughout the specification does not mean " step for.

Throughout this specification, the term " combination (s) thereof " included in the expression of the machine form means a mixture or combination of one or more elements selected from the group consisting of the constituents described in the expression of the form of a marker, Quot; means at least one selected from the group consisting of the above-mentioned elements.

Throughout this specification, the description of "A and / or B" means "A or B, or A and B".

Hereinafter, embodiments and examples of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to these embodiments and examples and drawings.

According to a first aspect of the present invention, there is provided a method of manufacturing a carbon nanotube dispersion, comprising: spraying and drying a dispersion of carbon nanotubes by a rapid thermal spray drying method to form carbon nanotube particles having dense carbon nanotubes; And coating a metal oxide on the dense carbon nanotube particles. The present invention also provides a method for producing a metal oxide-coated carbon nanotube composite particle.

In one embodiment of the present invention, the rapid thermal spray drying method may be, but not limited to, using a spray dryer.

In one embodiment herein, the rapid thermal spray drying may be performed at a temperature of from about 90 ° C to about 200 ° C, but is not limited thereto. For example, the rapid thermal spray drying may be performed at a temperature of from about 90 ° C to about 200 ° C, from about 90 ° C to about 150 ° C, from about 90 ° C to about 100 ° C, from about 100 ° C to about 200 ° C, But it is not limited thereto. The temperature may be the inlet temperature of the spray dryer, but may be, but is not limited to, the spraying of the carbon nanotube dispersion at a flow rate of about 2 mL / min.

In one embodiment of the invention, the metal oxide is one selected from the group consisting of MnO ₂ , RuO ₂ , Fe ₂ O ₃ , SnO ₂ , IrO _x , NiO _x , CoO _x , But may not be limited thereto.

In one embodiment of the present invention, the dense carbon nanotube particles may be spherical, but the present invention is not limited thereto. The dense carbon nanotube particles may be spherical carbon nanotube particles formed by dense carbon nanotubes.

In one embodiment of the present invention, the method may further include heat treatment after formation of the dense carbon nanotube particles, but the present invention is not limited thereto. The dense carbon nanotube particles may remove residual substances such as surfactant or solvent that may be contained in the carbon nanotube dispersion through the heat treatment.

In one embodiment herein, the heat treatment may be performed at a temperature of about 300 ° C to about 800 ° C, but may not be limited thereto. For example, the heat treatment may be performed at a temperature of about 300 캜 to about 800 캜, about 300 캜 to about 700 캜, about 300 캜 to about 600 캜, about 300 캜 to about 500 캜, To about 800 占 폚, from about 500 占 폚 to about 800 占 폚, from about 600 占 폚 to about 800 占 폚, or from about 700 占 폚 to about 800 占 폚.

In one embodiment of the present invention, the step of coating the metal oxide on the dense carbon nanotube particles includes adding an acid to the mixture including the dense carbon nanotube particles, the metal oxide precursor, and a solvent to form the dense carbon nanotube But the present invention is not limited thereto, and may include, but is not limited to, partially peeling and acid-treating the surface of the tube particles and then reacting them to obtain the metal oxide-coated carbon nanotube composite particles.

In one embodiment of the invention, the solvent may be, but not limited to, water.

In one embodiment herein, the reaction may be performed in a temperature range from ambient temperature to about 100 < 0 > C, but may not be limited thereto.

In one embodiment of the present invention, the coating amount of the metal oxide, the thickness of the coating, and the growth rate may be controlled according to the amount of the metal oxide precursor, but the present invention is not limited thereto.

The second aspect of the present invention provides a metal oxide-coated carbon nanotube composite particle comprising carbon nanotube-dense particles and a metal oxide coated on the particles.

In one embodiment herein, the composite particles may be, but are not limited to, those produced by the process according to the first aspect of the present disclosure. The second aspect of the present invention relates to a metal oxide-coated carbon nanotube composite particle prepared by the method of the first aspect of the present invention, and a detailed description of parts overlapping with the first aspect of the present invention is omitted, The description of the first aspect of the present invention can be equally applied to the second aspect even though the description thereof is omitted.

In one embodiment of the present invention, the dense particles of the carbon nanotubes may be spherical, but the present invention is not limited thereto. The dense carbon nanotube particles may be spherical carbon nanotube particles formed by dense carbon nanotubes.

In one embodiment of the invention, the metal oxide is one selected from the group consisting of MnO ₂ , RuO ₂ , Fe ₂ O ₃ , SnO ₂ , IrO _x , NiO _x , CoO _x , But may not be limited thereto.

A third aspect of the present invention provides an electrode material comprising metal oxide-coated carbon nanotube composite particles according to the second aspect of the present invention. The detailed description of the parts overlapping with the first aspect or the second aspect of the present invention is omitted, but the description of the first aspect or the second aspect of the present invention can be applied equally to the third aspect, .

 In one embodiment of the invention, the electrode material may be, but is not limited to, those used in supercapacitors.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto.

[Example]

≪ Preparation of manganese oxide-coated carbon nanotube composite >

In one embodiment of the present invention, in order to produce dense carbon nanotube particles, a carbon nanotube dispersion in which 5 wt% carbon nanotubes (Wonil Co.) is dispersed in water is sprayed onto the surface of the spray dryer using a spray drier (BUCHI) The mixture was sprayed at an inlet temperature of 140 ° C at a flow rate of 5 mL / min. Using the fluid force, spherical carbon nanotube particles having dense carbon nanotubes were obtained. The obtained dense carbon nanotube particles were subjected to heat treatment at 500 ° C. for 2 hours to remove the surfactant used in the carbon nanotube dispersion.

10 mg of the densified carbon nanotube particles and 80 mg of potassium permanganate as a manganese oxide precursor were stirred in deionized water for 30 minutes or 60 minutes in order to coat the densely spherical carbon nanotube particles obtained above with 10 mg of the densified carbon nanotube particles . 0.5 mu L of sulfuric acid was added to the mixed solution and stirred for 30 minutes or 60 minutes to partially peel and acid-treat the surface of the dense carbon nanotube particles. Thereafter, the mixed solution was stirred in an oil bath and reacted by heating at 80 ° C for 1 hour. The reaction mixture was put into 100 mL of deionized water to lower the temperature and diluted. The precipitate of the reaction mixture was washed several times with deionized water, and then dried at 60 ° C to obtain a carbon nanotube composite coated with a metal oxide. The amount of manganese oxide, the thickness of the coating, and the growth rate can be controlled depending on the amount of the potassium permanganate added.

<Characteristic Analysis>

A beaker-type 3-electrode system was used to measure the electrochemical properties of the sample. The 3-electrode cell comprises a manganese oxide-coated carbon nanotube composite-assembled film on a glass substrate as a working electrode, a Ag / AgCl electrode saturated as a reference electrode, and a counter electrode counter Pt rod was used as the electrode. Particularly, the working electrode is a mixture of a manganese oxide-coated carbon nanotube composite, DB-100 (conductive material) and a polyvinylidene fluoride (PVDF) binder (80:10:10 by weight) . The working electrode has a geometric surface of 1 cm ² containing 1.3 mg of manganese oxide-coated carbon nanotube complex. In this embodiment, a 1.0 M Na ₂ SO ₄ (Aldrich) solution was used as the electrolyte solution. The cyclic voltammetry (CV) and galvanostatic charge / discharge graphs were measured by VersaSTAT 3 (AMETEK). The CV is 0 to 1 V vs. the scan speed range (5 mV / s to 100 mV / s). Ag / AgCl (3 M NaCl). The constant current charge / discharge measurement was measured over a voltage range between 0 V and 1 V at a constant current of 0.5 to 10 A / g.

Scanning electron microscopy (SEM) images were obtained using field emission scanning electron microscopy (FESEM, Carl Zeiss, SUPRA 55 VP). Energy-dispersive spectroscopy (EDX, BRUKER, XFlash Detector 4010) Element mapping was performed to observe the distribution of N doping.

The spherical densely packed carbon nanotube particles (Comparative Example 1) prepared above, the manganese oxide-coated carbon nanotube composite particles (Example 1) coated with a small amount of manganese oxide in the above Example (Example 1) A low magnification and high magnification SEM image of manganese oxide-coated manganese oxide-coated carbon nanotube composite particles (Example 2) is shown in FIG.

2 (a) to 2 (d) show results of performing energy dispersive spectroscopy (EDS) mapping analysis of Comparative Example 1, Example 1, and Example 2. FIG.

As shown in FIG. 2, it can be confirmed that the coated manganese oxide is uniformly coated on the whole of the spherical carbon nanotube particles densified through the energy-spectral analyzer mapping analysis.

The spherical densely packed carbon nanotube particles (Comparative Example 1), the manganese oxide-coated carbon nanotube composite particles (Example 1) coated with a small amount of manganese oxide in the above Examples (Example 1), and the large amount of manganese oxide Galvanostat (AMETEK PAR, VersaSTAT3) was applied to the electrode material for the supercapacitor of the manganese oxide-coated carbon nanotube composite particles (Example 2) coated with the composition of Comparative Example 1 and Example 1 And cyclic voltammetry experiments of the particles obtained in Example 2 were carried out, and the results are shown in FIG.

As shown in Figure 3, cyclic voltammetry experiments were performed at the same scan rate of 10 mV / s in a 1 M Na ₂ SO ₄ electrolyte. The graph of the manganese oxide-coated carbon nanotube composite particles according to the first and second embodiments of the present invention shows a wider area of openings than the dense spherical carbon nanotube particles of Comparative Example 1, indicating that the electrochemical activity is better have. This means that the electrostatic capacitance is increased, and that manganese oxide-coated carbon nanotube composite particles (Examples 1 and 2) as the electrode material for a high-capacity super capacitor are more compact than spherical carbon nanotube particles (Comparative Example 1) It can have a high specific capacity.

Spherical densely packed carbon nanotube particles according to Comparative Example 1, manganese oxide-coated carbon nanotube composite particles according to Examples 1 and 2, and manganese oxide-coated carbon nanotube composite particles according to Comparative Example 2 A galvanostatic charge / discharge experiment was carried out to confirm the mass-dependent capacitance characteristics of the oxide nanoparticles, and the results are shown in FIG.

As shown in FIG. 4, in the same 1 M Na ₂ SO ₄ electrolyte, spherical densely packed carbon nanotube particles (Comparative Example 1) not coated with manganese oxide at the same constant current condition per unit mass (1 A / g) g, respectively, while manganese oxide-coated carbon nanotube composite particles (Examples 1 and 2) exhibited masses of 138 F / g and 347 F / g, respectively, depending on the amount of manganese oxide precursor The capacity was improved by 6 times and 15 times, respectively, as compared with Comparative Example 1, which was abruptly increased. In addition, the electrostatic capacity was 2.7 times and 6.7 times higher than that of the manganese oxide nanoparticles (Comparative Example 2) containing no spherical carbon nanotubes (52 F / g), respectively. Therefore, it is expected that the manganese oxide-coated carbon nanotube composite particles can be applied as a material capable of exhibiting very high capacitance characteristics as an electrode material of a supercapacitor.

In order to confirm the electrochemical stability of the particles according to Comparative Example 1, Comparative Example 2, Example 1, and Example 2, an experiment for evaluating lifetime characteristics in which charge and discharge at a constant current condition was repeated 1,000 times was performed, Is shown in Fig.

As shown in FIG. 5, in the same 1 M Na ₂ SO ₄ electrolyte, after 100 cycles of charging / discharging cycles under the same constant current condition (1 A / g) per unit mass, manganese oxide without spherical dense carbon nanotube particles (Comparative Example 1) and the manganese oxide-coated carbon nanotube composite particles (Examples 1 and 2) exhibited a low capacity of about 36% while the spherical dense carbon nanotube particles (Comparative Example 1) and the manganese oxide- 100% capacity maintenance and excellent lifetime characteristics. It is believed that this is due to the hierarchical pore structure of dense spherical carbon nanotube particles and the high electrical conductivity of the dense carbon nanotube particles. Therefore, the manganese oxide-coated carbon nanotube composite particles are expected to be applicable as electrode materials for supercapacitors, which exhibit excellent lifetime characteristics as well as high capacity characteristics.

It will be understood by those of ordinary skill in the art that the foregoing description of the embodiments is for illustrative purposes and that those skilled in the art can easily modify the invention without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (14)

Spraying and drying the dispersion of carbon nanotubes by rapid thermal spray drying to form carbon nanotube particles having dense carbon nanotubes; And
Coating the metal oxide on the dense carbon nanotube particles
Coated carbon nanotube composite particles.
The method according to claim 1,
The metal oxides are MnO _2, RuO _2, Fe ₂ O _3, SnO _2, IrO _x, NiO _x, CoO _x, and is made up of a combination thereof comprises is selected from the group, metal oxide-coated carbon A method for producing nanotube composite particles.
The method according to claim 1,
Wherein the rapid thermal spray drying method is carried out at a temperature of 90 ° C to 200 ° C.
The method according to claim 1,
Wherein the densified carbon nanotube particles are spherical. &Lt; RTI ID = 0.0 &gt; 21. &lt; / RTI &gt;
The method according to claim 1,
The method of manufacturing a metal oxide-coated carbon nanotube composite particle according to claim 1, further comprising heat treatment after formation of the dense carbon nanotube particles.
6. The method of claim 5,
Wherein the heat treatment is performed at a temperature of 300 to 800 占 폚.
The method according to claim 1,
The step of coating the dense carbon nanotube particles with the metal oxide may include adding an acid to the mixture including the dense carbon nanotube particles, the metal oxide precursor, and a solvent to partially peel the surface of the dense carbon nanotube particles And subjecting the mixture to an acid treatment followed by a reaction to obtain the metal oxide-coated carbon nanotube composite particles.
8. The method of claim 7,
Wherein the reaction is carried out at a temperature ranging from room temperature to 100 ° C.
The method according to claim 1,
Wherein the coating amount of the metal oxide coated, the thickness of the coating, and the growth rate are controlled in accordance with the amount of the metal oxide precursor.
Carbon nanotubes are densely packed and the metal oxide coated on the particles
And a metal oxide-coated carbon nanotube composite particle.
11. The method of claim 10,
Wherein the composite particles are produced by the method according to any one of claims 1 to 9. A metal oxide-coated carbon nanotube composite particle,
11. The method of claim 10,
The metal oxides are MnO _2, RuO _2, Fe ₂ O _3, SnO _2, IrO _x, NiO _x, CoO _x, and is made up of a combination thereof comprises is selected from the group, metal oxide-coated carbon Nanotube composite particles.
13. An electrode material comprising metal oxide-coated carbon nanotube composite particles according to any one of claims 10 to 12.
14. The method of claim 13,
Lt; RTI ID = 0.0 &gt; super capacitor. &Lt; / RTI &gt;

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