KR100895267B1 - AC/CNT Composite Electrode Using Electrostatic attraction and Method for Manufacturing the Same - Google Patents

Abstract

The present invention relates to an activated carbon / carbon nanotube composite electrode using electrostatic attraction and a method for manufacturing the same, and more particularly, to an activated carbon / carbon nanotube composite electrode having a low resistance and a method of manufacturing the same, including carbon nanotube carbon nanotube And a first step of preparing a precursor solution containing activated carbon; And a second step of forming the activated carbon / carbon nanotube composite electrode by moving the precursor solution onto the substrate by the electrostatic attraction generated according to the potential difference formed between the precursor solution and the substrate. A method of manufacturing an activated carbon / carbon nanotube composite electrode having a uniform thickness and a surface shape is provided.

Activated carbon, carbon nanotubes, electrodes, ultrasonic waves, electrostatic attraction

Description

Activated carbon / carbon nanotube composite electrode using electrostatic attraction and its manufacturing method {AC / CNT Composite Electrode Using Electrostatic attraction and Method for Manufacturing the Same}

The present invention relates to an activated carbon / carbon nanotube composite electrode using electrostatic attraction and a method of manufacturing the same. More specifically, an activated carbon / carbon nanotube composite electrode having a low resistance and a method for manufacturing the same, comprising: a first step of preparing a precursor solution including carbon nanotubes and activated carbon; And a second step of forming the activated carbon / carbon nanotube composite electrode by moving the precursor solution onto the substrate by the electrostatic attraction generated according to the potential difference formed between the precursor solution and the substrate. The present invention relates to a method for producing an activated carbon / carbon nanotube composite electrode having a uniform thickness and a surface shape.

Generally, since activated carbon has a large specific surface area due to its porosity, it is usefully used as an electrode material such as Electric Double Layer Capacitor (EDLC).

An electric double layer capacitor (hereinafter referred to as "EDLC"), which is one of electrochemical capacitors, has an ion layer called an electric double layer formed at an interface between an electrode and an electrolyte, unlike a conventional battery, in which a mechanism for storing electricity uses a chemical reaction. The charge is stored in the ionic layer, and the specific principle of EDLC is as follows.

EDLCs, like most batteries, consist of two electrodes, which are deposited in an electrolyte. When a potential difference is applied between two electrodes, that is, when a voltage is applied and charged, charges accumulate. Electrons move from the cathode of the voltage source to the cathode of the EDLC, forming an ion layer between the electrode and the electrolyte. Negative ions in the electrolyte move to the anode through the electrolyte, repelled by the electrons accumulated in the cathode, to form another ion layer. This accumulation of charge on both electrodes continues until it equals the potential difference of the charging source.

As described above, EDLC uses a pair of charge layers (electric double layers) having different signs at the interface of the electrolyte, and deterioration due to repetition of the charge / discharge operation is very small, and thus the cycle life is not limited. It is environmentally friendly and does not require maintenance. Accordingly, EDLC is mainly used in the form of IC backup of various electric and electronic devices, and recently, its use has been expanded and widely applied to toys, solar energy storage, HEV power supplies, and the like. It is also used as a battery replacement for products that do not require a lot of energy and require a long lifespan, thus expanding the application range.

As the electrode of the EDLC as described above, an electrode active material mainly composed of activated carbon is used. EDLC electrode using activated carbon has an advantage that the capacity is dramatically increased compared to the existing electrolytic capacitor, and does not destroy even if the polarity is changed. The capacitance of the EDLC is determined by the amount of charge accumulated in the electric double layer, and the amount of charge becomes larger as the specific surface area of the electrode is larger. Therefore, since activated carbon has a high specific surface area due to porosity, it is possible to increase the capacity of the electrode and improve the energy density. In addition, the average pore size and pore distribution characteristics of activated carbon affect the mobility of adsorption ions, thereby improving output characteristics. Generally used activated carbon for EDLC electrodes has a specific surface area of 1500 to 3000 m 2 / g and an average pore size distribution of 10 to 20 m 3.

However, activated carbon has the same characteristics as above, but electrical conductivity (conductivity) has been pointed out a problem. Accordingly, a conductive agent for improving electric conductivity is added to the electrode active material. In general, in manufacturing an electrode for EDLC, the porous activated carbon particles as the active material, the conductive agent for electrically connecting the porous activated carbon particles, and the binder for bonding them are physically mixed, and then mixed in a specific solvent, and mixed again to form a slurry. After making a form, it is coated on the current collector to a desired thickness to produce an electrode. In this case, mainly carbon black is used as the conductive agent. In addition, recently, a technique of manufacturing an activated carbon / carbon nanotube composite electrode form by applying a carbon nanotube (CNT) having excellent conductivity as a conductive agent has been attempted.

However, the conventional electrode manufacturing method as described above, the mixing of the activated carbon and the conductive carbon black is made through physical mixing, there is a problem that takes a long time for sufficient mixing of the activated carbon and the conductive carbon black. In addition, in order to sufficiently activate activated carbon to express the capacity of all of the activated carbons, about 20 to 25% by weight of conductive carbon black is required. Accordingly, there is a problem in that the content of activated carbon is relatively small, thereby reducing the effect (increase in capacity, etc.) according to the use of activated carbon.

In addition, when using carbon nanotubes (CNT) having excellent conductivity as a conductive agent, uniform mixing of activated carbon and carbon nanotubes (CNT) is difficult due to the inherent entanglement characteristics of carbon nanotubes (CNT). In addition, in the case of manufacturing a composite electrode using activated carbon and carbon nanotubes as described above, it is difficult to uniformly mix activated carbon and carbon nanotubes (CNT), thereby reducing electrode resistance only by adding about 15% by weight or more of carbon nanotubes. The charge / discharge characteristics at high rates appear the same. Accordingly, there is a problem in that the amount of activated carbon is relatively reduced by the addition of a large amount of carbon nanotubes, so that the effect (increase in capacity, etc.) due to the use of activated carbon, as in the carbon black, is inferior.

On the other hand, as described above, the electrode active material for producing a conventional electrode for EDLC is manufactured in the form of a slurry, and then coated on a current collector, at this time it is difficult to control the thickness and mass in the individual electrode, repeated repeatability There is no problem. In addition, it is pointed out that it is difficult to ensure uniformity of the surface of the coated thin film.

The present invention is to solve the problems of the prior art as described above, in the production of the activated carbon / carbon nanotube composite electrode, to achieve a mixture of activated carbon and carbon nanotubes, which was difficult in the conventional slurry electrode manufacturing method, in the solution, By forcibly dispersing the entangled carbon nanotubes by ultrasonication, it enables uniform dispersion of activated carbon and carbon nanotubes, and activated carbon / carbon nanotubes having excellent electrical conductivity (low resistance) even by the addition of a small amount of carbon nanotubes. Its purpose is to provide a composite electrode and a method of manufacturing the same.

In addition, the present invention is spraying the uniformly dispersed solution (mixed solution of activated carbon and carbon nanotubes) on the substrate (current collector), so that the sprayed solution is sprayed by the electrostatic field generator to move by electrostatic attraction It is an object of the present invention to provide a method for producing an activated carbon / carbon nanotube composite electrode having excellent repeatability and uniform surface shape by securing a uniform thickness. In addition, an object of the present invention is to provide an activated carbon / carbon nanotube composite electrode and a method of manufacturing the same that can freely adjust the thickness of the electrode through the control of the injection conditions.

The present invention to achieve the above object,

A first step of preparing a precursor solution containing carbon nanotubes and activated carbon (preparation of a precursor solution); And

A second step of forming the activated carbon / carbon nanotube composite electrode by moving the precursor solution onto the substrate by the electrostatic attraction generated according to the potential difference formed between the precursor solution and the substrate (composite electrode forming step)

It provides a method for producing an activated carbon / carbon nanotube composite electrode comprising a.

At this time, the precursor solution production step is a) a carbon nanotube acid treatment step; B) pulverizing the activated carbon; Or c) mixing and stirring carbon nanotubes, activated carbon, a binder, and a solvent.

In addition, the composite electrode forming step is an electrostatic aerosol spray device (Electrostatic Aerosol Spray Pyrolysis device; this is abbreviated as "EASP device" in the present invention), the injector capable of spraying the precursor solution in the form of aerosol; A substrate support capable of supporting a substrate and charging the substrate; And a power generator for providing a potential difference to the injector and the substrate support.

In addition, the method of manufacturing the activated carbon / carbon nanotube composite electrode according to the present invention preferably further includes a third step of compressing the activated carbon / carbon nanotube composite electrode formed in the second step.

In addition, the present invention,

Board; And

In the activated carbon / carbon nanotube composite electrode comprising an electrode active material layer formed on the substrate,

The electrode active material layer includes carbon nanotubes and activated carbon, and includes 2.0 to 20.0 parts by weight of carbon nanotubes based on 100 parts by weight of the mixture of carbon nanotubes and activated carbon, and has an resistance of 2 to 4 Ω / cm 2. It provides a tube composite electrode.

According to the present invention, the precursor solution is moved onto the substrate by the electrostatic attraction generated by the potential difference formed between the precursor solution and the substrate to form an activated carbon / carbon nanotube composite electrode. Therefore, it is deposited with a uniform thickness and excellent repeatability, the deposited composite electrode has a uniform surface shape. In addition, the thickness of the composite electrode can be freely adjusted by controlling the injection amount.

In addition, according to a preferred embodiment of the present invention, the carbon tube powder is uniformly dispersed in the solution by ultrasonic irradiation with acid treatment. Accordingly, the carbon nanotubes are hydrophilic and have no entanglement. The carbon nanotubes are uniformly dispersed among the activated carbon particles, thereby exhibiting excellent electrical conductivity even by the addition of a small amount.

In addition, the composite electrode according to the present invention has a low resistance even by the addition of a small amount of carbon nanotubes can be spread at a low price, and has the effect of exhibiting excellent electrical properties.

Hereinafter, with reference to the accompanying drawings will be described the present invention in more detail.

A method of manufacturing an activated carbon / carbon nanotube composite electrode according to the present invention may occur according to a first step of preparing a precursor solution containing carbon nanotubes and activated carbon (a precursor solution manufacturing step) and a potential difference formed between the precursor solution and a substrate. At least a second step (composite electrode forming step) of moving the precursor solution onto the substrate by the electrostatic attraction to form an activated carbon / carbon nanotube composite electrode, and compressing the activated carbon / carbon nanotube composite electrode. It may further comprise a step (compression step).

At this time, the forming of the composite electrode is performed in an electrostatic field generator, preferably an EASP device (electrostatic aerosol spraying device) capable of arbitrarily controlling the injection amount of the precursor solution and the temperature of the substrate while generating the electrostatic field. First, the EASP device will be described.

Figure 1 shows a cross-sectional configuration of the EASP device preferably applied to the present invention.

The EASP device, when described with reference to Figure 1, the injector 10 capable of injecting a precursor solution; A substrate support 20 for supporting a substrate S and charging the substrate S; And a power generator 30 which provides a potential difference between the injector and the substrate support. The EASP apparatus includes heat supply means 25 for supplying heat to the substrate; A temperature controller 40 for controlling the temperature of the substrate; And it is preferable to further include a flow controller 50 for controlling the injection amount of the precursor solution. In FIG. 1, reference numeral E denotes a composite electrode formed on the substrate S. In FIG.

In addition, a nozzle 15 is mounted at a lower end of the injector 10, and the high voltage DC power generator 30 is electrically connected to the nozzle 15 of the injector 10 and the substrate support 20. A strong electrostatic field is formed between the 10 and the substrate support 20. The flow controller 50 precisely controls the injection amount of the precursor solution by precisely adjusting the moving speed of the piston embedded in the injector 10, and such a flow controller 50 is preferably useful to use the electronic flow controller have. In addition, the heat supply means 25 mounted in the substrate support 20 is included in the present invention as long as it can supply heat to the substrate 20 to evaporate the solvent of the precursor solution sprayed on the substrate S. For example, the heat supply means 25 may be selected from a lamp (eg, a halogen lamp), a resistance heating wire or a heater. The temperature controller 40 compares the heat sensed by a temperature sensor such as a thermocouple with a preset heat, and controls the heat supply means 25 to maintain a constant temperature of the substrate S. In addition, the EASP device may further include a distance adjuster (not shown) for adjusting the distance between the injector 10 and the substrate support 20.

According to the present invention, in the case of using the EASP device as described above, a precursor solution (a solution in which activated carbon, carbon nanotubes and a binder are uniformly dispersed in a solvent) is sprayed onto the substrate by an electrostatic attraction to a uniform thickness. At the same time, the solvent in the precursor solution sprayed by the heat generated from the heated substrate S may be evaporated to easily manufacture the activated carbon / carbon nanotube composite electrode E. That is, the activated carbon / carbon nanotube composite electrode E is fixed to the substrate S by evaporation without a separate drying process.

More specifically, the sprayed solution is sprayed in a very small liquid droplet state that can overcome the surface tension of the solvent from the nozzle 15 under the influence of the applied electrostatic field, the sprayed solution moves along the electrostatic field And very evenly deposited on the negatively charged substrate.

Figure 2 is a flow chart showing in detail each step of the method for producing an activated carbon / carbon nanotube composite electrode according to an embodiment of the present invention. Hereinafter, the manufacturing method according to the present invention will be described in detail for each step.

Producing Solution (Step I)

The first step of the method for producing an activated carbon / carbon nanotube composite electrode according to the present invention is to prepare a precursor solution containing carbon nanotubes and activated carbon.

First, carbon nanotube (CNT) powder is prepared. The carbon nanotube powder used in the present invention is not particularly limited, and includes all single layer carbon nanotubes, multilayer carbon nanotubes, and mixtures thereof. In this case, since the general carbon nanotube powder exhibits hydrophobicity and does not disperse in a solvent such as water, it is preferable to include the step a) of acid treating the carbon nanotubes to impart hydrophilicity.

In the acid treatment step, carbon nanotube powders are immersed in an aqueous solution of strong acid to dissolve and remove metal catalysts contained in the production of carbon nanotube powder with strong acid, as well as carbon nanotubes exhibiting hydrophobic properties not dispersed in a solvent such as water. A functional group is provided on the surface of the powder to impart hydrophilicity to the carbon nanotubes so that the carbon nanotube powders can be easily dispersed in the solvent.

When explaining the acid treatment step in more detail, it is preferable to put a suitable amount of carbon nanotube powder in an aqueous solution of a strong acid and heat to soak at a temperature of about 60 to 90 ℃ acid treatment. The strong acid may be, for example, sulfuric acid, nitric acid, hydrochloric acid or a mixture thereof. At this time, if the temperature of the strong acid solution is less than 60 ℃ can not give chemical change to the chemically limited carbon nanotubes, it is difficult to impart hydrophilicity, if the temperature exceeds 90 ℃ strong acid boils explosively to affect the surrounding environment It is undesirable because it can cause accidents. Therefore, the acid treatment is preferably carried out in a strong acid aqueous solution in the above temperature range. In addition, although processing time is not specifically limited, It is good to process for 2 hours or more. If the treatment time is less than 2 hours, it may be difficult to impart hydrophilicity because the carbon nanotubes do not cause sufficient chemical deformation. At this time, even if the processing time is more than 6 hours, it is difficult to show the increased effect of increasing the time. Therefore, the acid treatment is preferably performed for 2 to 6 hours.

Next, the acid treated aqueous solution is filtered and separated from the aqueous solution through a filter, and the carbon nanotubes are filtered and washed several times with distilled water. Then, heat is applied to the cleaned carbon nanotubes to evaporate moisture to make the powder again.

In addition, the activated carbon used in the production method according to the present invention includes commercially available activated carbon, for example, a particle size of about 10 to 20 ㎛, the specific surface area of about 1700 m2 / g to prepare a conventional EDLC electrode Activated carbon used in the process.

At this time, the use of the activated carbon, without being blocked by the injector nozzle 15 of the EASP device, comprising the step of b) pulverizing the activated carbon to achieve a smooth injection and uniform dispersion with the carbon nanotubes in the solution It is desirable to. For example, it is preferable to use finely pulverized the particle size of activated carbon by 5 micrometers or less, specifically, 1-5 micrometers through a roll milling or a ball milling process.

On the other hand, the first step of the method for producing an activated carbon / carbon nanotube composite electrode according to the present invention preferably includes a step c) of mixing and stirring carbon nanotubes, activated carbon, a binder, and a solvent.

The binder may be used as commonly used, for example, polyvinyl alcohol (PVA; polyvinyl alcohol), polyvinyl butyral (PVB; polyvinyl butyral), polyvinylpyrrolidone (PVP; poly-N-vinylpyrrolidone) Or a mixture of one or two or more selected from carboxymethylcellulose (CMC; carboxymethylcellulose), polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE). The binder is preferably a fluorine-based polyvinylidene fluoride (PVDF; polyvinylidenefloride), polytetrafluoroethylene (PTFE; poly-tetrafluoroethylene) and a mixture thereof may be usefully used. Such a binder may be mixed at 1.0 to 20.0 parts by weight based on 100 parts by weight of the mixed powder of carbon nanotubes and activated carbon. If the content of the binder is less than 1.0 parts by weight, the bonding strength between the solids (carbon nanotubes and activated carbon) is lowered. If the content of the binder exceeds 20.0 parts by weight, the content of carbon nanotubes and activated carbon is relatively small, which is not preferable. The binder may be preferably mixed in an amount of 2.0 to 5.0 parts by weight based on 100 parts by weight of the mixed powder of carbon nanotubes and activated carbon. In addition, when using the said binder, it is good to dilute and use in organic solvents, such as N-methyl- 2-pyrrolidone (NMP) and alcohol.

Dispersing solvents for dispersing the carbon nanotubes, activated carbon and the binder as described above include water, an organic solvent or a mixture thereof. Preferably a mixture of water and an organic solvent can be used.

In addition, according to a preferred embodiment of the present invention, the dispersing solvent has a low boiling point (boiling point), it is preferable to use the solvent itself is lower than the density of carbon nanotubes or activated carbon. For example, a low breaking point such as water or alcohol (eg, methanol, ethanol, etc.) and a low density can be usefully used, and the reason is as follows.

When spraying the precursor solution in which the activated carbon, carbon nanotube and binder are dispersed on the substrate S through the EASP device, the solvent does not evaporate smoothly in the case of a solvent having a high breaking point, so the activated carbon and carbon nanotube particles are in an aerosol state. As a result, it is not deposited on the substrate S, and the characteristics of the composite electrode E thin film formed on the substrate S may also be degraded. In addition, when the density of the solvent itself is high, activated carbon and carbon nanotube powder do not easily go away, so that it is difficult to smoothly disperse. Accordingly, the solvent has a relatively low breaking point, and it is preferable to use water, alcohol, or a mixture thereof having a lower density than activated carbon and carbon nanotubes.

Meanwhile, in step c), the carbon nanotubes are forcibly released and the carbon nanotubes are agitated so that the carbon nanotubes are uniformly dispersed and the carbon nanotubes, the activated carbon, the binder, and the solvent are stirred by ultrasonic treatment. Such ultrasonic treatment is not particularly limited, and the intensity and time of the ultrasonic wave may be appropriately adjusted as necessary.

In preparing the precursor solution as described above, the carbon nanotubes are not particularly limited, but may be prepared to include 2.0 to 20.0 parts by weight based on 100 parts by weight of the mixed powder of carbon nanotubes and activated carbon. If the content of carbon nanotubes is less than 2.0 parts by weight, it is difficult to achieve the effect (improving electrical conductivity, etc.) due to the content of carbon nanotubes, and if the content of carbon nanotubes exceeds 20.0 parts by weight, the content of activated carbon is relatively small (capacity) Increase, etc.) is difficult. The carbon nanotubes may be prepared to be included in an amount of preferably 2.0 to 15.0 parts by weight, more preferably 3.0 to 10.0 parts by weight, based on 100 parts by weight of the mixed powder of carbon nanotubes and activated carbon.

At this time, if the content of the carbon nanotube powder is too low, it is difficult to achieve the effect (conductivity improvement, etc.) according to the content of the carbon nanotube, on the contrary, if the content of the carbon nanotube powder is too high, the content of activated carbon is relatively small, It is difficult to plan the effect (increase in capacity, etc.) according to the content. According to the present invention, by the acid treatment and ultrasonic irradiation, the carbon nanotubes are uniformly dispersed in the solution without entanglement, and excellent electricity is also achieved by adding a small amount (eg, 5.0 parts by weight) without containing 15 parts by weight or more as in the prior art. Exert conductivity.

Compound Electrode Formation Step (Step II)

As described above, after preparing a precursor solution in which carbon nanotube powder and activated carbon are uniformly dispersed, the precursor solution is electrostatically sprayed onto the substrate S using an EASP apparatus.

At this time, the substrate (S) that can be used includes a conductor, a non-conductor and a semiconductor, for example, may be selected from materials such as glass, plastic and metal. The substrate S is preferably mainly used as a current collector when manufacturing an electric double layer capacitor (EDLC), and a metal selected from titanium (Ti), nickel (Ni), aluminum (Al), alloys thereof, and the like. It is good that the foil is excellent in electrical conductivity such as foil and is not easily deformed even when subjected to physical shock.

Referring to FIG. 1, which shows an EASP device, the high voltage DC power generator 30 is connected between the nozzle 15 of the injector 10 and the substrate support 20 to provide the EASP device. The nozzle 15 is charged with (+) and the substrate S in contact with the substrate support 20 is charged with (−).

When an appropriate amount of the precursor solution in which activated carbon, carbon nanotubes and a binder are uniformly dispersed on the solvent is injected through the injector 10, liquid droplet particles including carbon nanotubes are formed by electrostatic attraction due to an electrostatic field. It is sprayed in the aerosol form toward the charged substrate (S), and moves in a uniform distribution to the substrate (S) along the electrostatic field. Subsequently, the substrate S is heated by the heat transferred from the heat supply means 25, and the solvent in the precursor solution is evaporated by the heat of the heated substrate S to activate the activated carbon / carbon nanotube composite electrode E on the substrate S. ) Is fixed and formed by vapor deposition. In this process, by controlling the injection amount of the precursor solution by the flow controller 50 of the EASP device it is possible to freely adjust the thickness of the composite electrode (E).

At this time, it is good to maintain the temperature of the substrate (S) to about 100 ~ 200 ℃ through the temperature controller 40 of the EASP device. When the temperature is less than 100 ° C., all of the solvents (ethanol, etc.) contained in the injected precursor solution do not evaporate and are not deposited on the substrate S in an aerosol state, thereby deteriorating the characteristics of the thin film. If the temperature is set to an excessive temperature, the liquid in the droplet state evaporates before the solvent (ethanol, etc.) contained in the injected precursor solution arrives on the substrate S, so that the light activated carbon and carbon nanotube particles are blown off into the air. This is because the amount deposited on the substrate S becomes very small.

Crimping Step (Step III)

As described above, after manufacturing the activated carbon / carbon nanotube composite electrode E, the composite electrode E is separated from the EASP device and compressed. This is to increase the physical stability of the produced activated carbon / carbon nanotube composite electrode (E), it is possible to remove the peeling and instability of the electrode generated during the electrochemical experiment through this step. In addition, the pressurization greatly increases the contact between activated carbon and carbon nanotubes, thereby facilitating the movement of electrons through uniformly dispersed carbon nanotubes in the electrode. It is possible to secure the electrical conductivity of. This pressing step can be carried out, for example, via a roll pressing process.

Meanwhile, the activated carbon / carbon nanotube composite electrode according to the present invention includes a substrate and an electrode active material layer formed on the substrate. In this case, the electrode active material layer includes carbon nanotubes and activated carbon. The carbon nanotubes constituting the electrode active material layer are included in an amount of 2.0 to 20.0 parts by weight based on 100 parts by weight of the mixture of carbon nanotubes and activated carbon. The carbon nanotubes are preferably included in an amount of 2.0 to 15.0 parts by weight based on 100 parts by weight of the mixture of carbon nanotubes and activated carbon. In addition, the electrode active material layer has an electrode resistance of 2 ~ 4 Ω / ㎠. And the electrolyte resistance of the electrode active material layer may have a 0.5 ~ 1 Ω / ㎠.

The composite electrode according to the present invention as described above has a low resistance even by the addition of a small amount of carbon nanotubes can be supplied at a low price, and has a relatively high content of activated carbon content. At this time, the electrode active material layer is preferably formed by the production method of the present invention. That is, the precursor solution as described above is formed by spraying and depositing through the EASP apparatus.

Hereinafter, specific test examples of the present invention will be described. The following examples are merely provided to explain the present invention in more detail, whereby the technical scope of the present invention is not limited.

EXAMPLE

First, the carbon nanotube (CNT) powder is acid-treated using an aqueous sulfuric acid solution, and then the acid-treated carbon nanotube (CNT) powder, activated carbon, and binder (PVDP) are mixed with an ethanol aqueous solution, and then ultrasonically irradiated. A precursor solution in which each component was uniformly dispersed was prepared. At this time, the activated carbon was used after pulverizing a conventional activated carbon having a particle size of 10 ~ 20㎛ to a particle size of 1 ~ 5㎛ through a ball milling process. In addition, the carbon nanotubes (CNT) was prepared while changing the content of the carbon nanotubes (CNT) to 0, 5, 10, 15, 20wt% based on the weight of the mixed powder consisting of activated carbon, as shown in Figure 1 A composite electrode was manufactured by spraying and depositing on a substrate S using an EASP apparatus.

3a to 3e is a surface shape of the composite electrode prepared while changing the carbon nanotube content of 0, 5, 10, 15, 20wt% in the production of activated carbon / carbon nanotube composite electrode according to an embodiment of the present invention Scanning Electron Microscopy (SEM) photographs taken for observation. In this case, Figure 3a is a photograph taken at 2500 times magnification of a composite electrode made of pure activated carbon without adding carbon nanotubes. 3B to 3E are photographs taken at 10,000 times the surface of the manufactured composite electrode while increasing the ratio of carbon nanotubes to 5, 10, 15, and 20 wt%.

First, activated carbon particles having a size of 1 to 5 μm can be observed as in FIG. 3A. This indicates that activated carbon having a particle size of 10 to 20 μm was evenly ground through ball milling.

In addition, as can be seen in Figure 3b it can be seen that the carbon nanotubes are evenly dispersed between the activated carbon particles. This indicates that carbon nanotubes were evenly dispersed through the solution phase dispersion of activated carbon and carbon nanotubes and the EASP device, thereby producing an electrode. And as shown in Figure 3b, it can be seen that the activated carbon and carbon nanotubes are formed throughout the electrode having a porous three-dimensional structure.

In addition, as can be seen in Figures 3c to 3e, it can be seen that the carbon nanotube particles are increased throughout the electrode as the content of the carbon nanotubes are increased, when more than 10wt% carbon nanotubes are added. It can be seen that the surface of the activated carbon is covered.

Meanwhile, FIGS. 4A to 4C illustrate the preparation of activated carbon / carbon nanotube composite electrodes according to an embodiment of the present invention, wherein the precursor solution containing 5 wt% of carbon nanotubes is added for 1 hour, 2 hours, and 3 hours, respectively. SEM image of a cross section of a composite electrode prepared by spraying through a device. As can be seen in the cross-sectional photograph of Figure 4a to 4c, it can be seen that the thickness of the activated carbon / carbon nanotube composite electrode increases in proportion to the injection time. In addition, it can be seen that a composite electrode having a uniform surface throughout the electrode was manufactured. Table 1 shows the amount and weight of the precursor solution sprayed from the EASP apparatus and the thickness of the composite electrode formed corresponding to each of them.

1 hours 2 hours 3 hours Weight (mg) 4.9 10.2 15.4 Thickness (㎛) 50 100 150

5 is a composite electrode prepared by changing the content of carbon nanotubes to 0, 5, 10, 15, 20wt% in the production of activated carbon / carbon nanotube composite electrode according to an embodiment of the present invention at a scanning speed of 200mV Cyclic voltammetry results are shown.

As can be seen from the experimental results of FIG. 5, in a pure activated carbon electrode not added with carbon nanotubes at a fast scan speed of 200 mV, a rectangular shape unique to the activated carbon electrode cannot be found. On the other hand, after 5wt% of carbon nanotubes are added, an activated carbon / carbon nanotube composite electrode can observe a rectangular shape unique to activated carbon.

This indicates that sufficient electrical conductivity was secured in the composite electrode after 5 wt% of carbon nanotubes were added. In addition, it can be seen from FIG. 5 that the composite electrode having sufficient electrical conductivity due to the addition of carbon nanotubes has a much larger capacity than the electrode that is not.

6 is an electrochemical impedance spectroscopy of the composite electrode prepared while changing the carbon nanotube content to 0, 5, 10, 15, 20wt% in the production of activated carbon / carbon nanotube composite electrode according to an embodiment of the present invention The results of the Nyquist plot obtained through Electrochemical Impedance Spectroscopy (EIS) experiment are shown.

As can be seen from the experimental results of FIG. 6, electrode resistance decreases sharply after 5 wt% of carbon nanotubes are added compared to the electrode without carbon nanotubes, and there is no significant change thereafter. . It can be seen that after the 5 wt% carbon nanotubes are added, sufficient electrical conductivity is ensured in the electrode, thereby smoothing the movement of electrons and thereby significantly reducing the electrode resistance.

The composite electrode obtained according to the manufacturing method of the present invention can be standardized to a desired size through a process such as punching, cutting, etc., can be usefully used as an electrode such as an electric double layer capacitor (EDLC). However, the present invention is not limited thereto and may be used as an electrode of an energy storage device such as a fuel cell or a hybrid battery.

Figure 1 shows a cross-sectional configuration of the EASP device preferably applied to the present invention.

2 is a flowchart illustrating a method of manufacturing an activated carbon / carbon nanotube composite electrode according to an exemplary embodiment of the present invention.

3A to 3E illustrate the surface shape of the composite electrode manufactured by changing the content of carbon nanotubes 0, 5, 10, 15, and 20 wt% in the preparation of the activated carbon / carbon nanotube composite electrode according to the embodiment of the present invention. It is a SEM photograph measured to observe.

4A to 4C are SEM photographs measured to observe the thickness change of the composite electrode manufactured by varying the injection time of the EASP device in manufacturing the activated carbon / carbon nanotube composite electrode according to the embodiment of the present invention.

5 is a composite electrode prepared while changing the content of carbon nanotubes to 0, 5, 10, 15, 20wt% in the production of activated carbon / carbon nanotube composite electrode according to an embodiment of the present invention at a scan rate of 200mv A graph showing the results of cyclic voltammetry.

6 is an electrochemical impedance spectroscopy of the composite electrode prepared while changing the carbon nanotube content to 0, 5, 10, 15, 20wt% in the production of activated carbon / carbon nanotube composite electrode according to an embodiment of the present invention (Electrochemical Impedance Spectroscopy) is a graph showing the results of the experiment.

<Description of Symbols for Major Parts of Drawings>

10: injector 15: nozzle

20: substrate support 25: heat supply means

30: power generator 40: temperature controller

50: flow regulator S: substrate

Claims (19)

A first step of preparing a precursor solution containing carbon nanotubes and activated carbon; And A second step of forming the activated carbon / carbon nanotube composite electrode by moving the precursor solution onto the substrate by an electrostatic attraction generated according to a potential difference formed between the precursor solution and the substrate; In the first step, a precursor solution is prepared by mixing and stirring carbon nanotubes, activated carbon, a binder, and a solvent. The solvent is a method for producing an activated carbon / carbon nanotube composite electrode, characterized in that the density is lower than the density of carbon nanotubes or activated carbon. The method of claim 1 wherein the first step is A process for producing an activated carbon / carbon nanotube composite electrode comprising the step of a) treating carbon nanotubes with an acid. The method of claim 2, wherein step a) A method for producing an activated carbon / carbon nanotube composite electrode, characterized in that the carbon nanotubes are treated in a strong acid solution at 60 to 90 ° C. The method of claim 1 wherein the first step is A method for producing an activated carbon / carbon nanotube composite electrode, characterized in that the precursor solution is prepared to include 2.0 to 20.0 parts by weight of carbon nanotubes based on 100 parts by weight of the mixture of carbon nanotubes and activated carbon. The method of claim 1 wherein the first step is Method for producing an activated carbon / carbon nanotube composite electrode comprising the step of b) pulverizing the activated carbon. The process of claim 5, wherein step b) A method for producing an activated carbon / carbon nanotube composite electrode, comprising pulverizing activated carbon to a particle size of 5 μm or less. delete The method of claim 1, The binder is an activated carbon / carbon nanotube composite electrode, characterized in that at least one organic binder selected from polyvinyl alcohol, polyvinyl butyral, polyvinylpyrrolidone, carboxymethyl cellulose, polyvinylidene fluoride and polytetrafluoroethylene. Manufacturing method. The method of claim 1 wherein the first step is A method for producing an activated carbon / carbon nanotube composite electrode, characterized in that the mixture is stirred by mixing 1.0 to 20.0 parts by weight of a binder with respect to 100 parts by weight of a mixture of carbon nanotubes and activated carbon. delete The method of claim 1 wherein the first step is A method for producing an activated carbon / carbon nanotube composite electrode, characterized in that the carbon nanotubes, activated carbon, binder and solvent are stirred by ultrasonication. The method of claim 1 wherein the second step is An injector capable of injecting a precursor solution; A substrate support capable of supporting a substrate and charging the substrate; And moving the precursor solution onto the substrate by using an injector including an injector and a power generator for providing a potential difference to the substrate support. The method of claim 12, The injection device comprises: heat supply means for supplying heat to the substrate; A temperature controller for controlling the temperature of the substrate; And a flow rate controller for controlling the injection amount of the precursor solution. The method of claim 12, The temperature of the substrate is a method of manufacturing an activated carbon / carbon nanotube composite electrode, characterized in that it is maintained at 100 ℃ ~ 200 ℃. The method of claim 1, Method for producing an activated carbon / carbon nanotube composite electrode further comprises a third step of pressing the activated carbon / carbon nanotube composite electrode formed in the second step. delete delete delete delete

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