KR101096598B1 - Electrode Composition and Electrode for Super Capacitor Using Binder Including Carbon-nano-fiber and Method for Manufacturing the Same - Google Patents

Abstract

The present invention relates to an electrode composition for a supercapacitor, an electrode, and a method of manufacturing the electrode, using a binder containing carbon nanofibers for producing an electrode by replacing a binder used in manufacturing an electrode with carbon nanofibers. .

The present invention is an electrode active material made of a porous carbon material; Conductive agents for imparting conductivity; And it provides an electrode composition for a super capacitor comprising a binder containing carbon nanofibers.

Super Capacitor, Electrode, Carbon Nanofiber, Binder

Description

Electrode Composition and Electrode for Super Capacitor Using Binder Including Carbon-nano-fiber and Method for Manufacturing the Same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode for a super capacitor, wherein an electrode for a super capacitor using a binder containing carbon nanofibers is prepared by replacing a binder used in manufacturing an electrode with carbon nanofibers. It relates to a composition, an electrode, and a method for producing the electrode.

Recently, with the rapid development of new electronic technology, there is a need for a more stable and powerful energy storage medium, and an interest in research on super capacitors as a power storage system capable of instant charging and discharging has been focused.

The electrode used in the supercapacitor is composed of an electrode material including an active material, a conductive agent and a binder, and a general electrode composition includes about 70-80% of an active material (for example, activated carbon) and a conductive agent (for example, carbon). Black) at about 5-20% and binder at about 3-30%.

A binder (also called a binder) serves as a crosslinking role for bonding an active material and a conductive agent constituting an electrode material. Examples of the binder include CMC (carboxy methyl cellulose), polyvinylpyrrolidone (PVP; polyvinylpyrrolidone), Fluorine-based polytetrafluoroethylene (PTFE) powders and emulsions, and rubber-based styrene butadiene rubber (SBR). These binders are polymer-based binders and are mostly non-conductive. to be.

Looking at the characteristics of each of these binders, CMC (carboxy methyl cellulose) serves to increase the binding strength with the current collector while maintaining the viscosity of the slurry in a state similar to the grass. CMC has the advantage of increasing the binding force, but after the slurry is cast (cast) rather has the disadvantage of increasing the embrittlement of the electrode material layer (casting). However, without using the CMC, it is very difficult to obtain a binding force between the current collector and the slurry, and is currently used as an electrode material.

Polyvinylpyrrolidone (PVP) acts as a dispersant and helps to disperse the particles in the slurry. However, if there is a small amount of addition and there are other substances that can help the dispersion, it is possible to replace it.

Polytetrafluoroethylene (PTFE) is encapsulated in an emulsion state inside the slurry, and when melted above the melting point (327 ° C.), the polymer surrounds the particles like a spider web. However, the melting point is so high that it is very difficult to activate it by raising the temperature or by applying pressure. Also be a F (fluorine) in the course of charge / discharge decomposition HF in combination with H (hydrogen) that is present in the product ^- formed by the drops significantly the characteristics of the product. Nevertheless, the reason why it is used as an electrode material is that it is difficult to find a material that can stably increase the bonding force between particles as PTFE.

Rubber-based styrene butadiene rubber (SBR) serves to protect the surface by coating the surface of the particles. Although it has the disadvantage of increasing the resistance due to the drop in electrical conductivity, it is widely used as a general electrode material because of its advantages over the disadvantage.

In consideration of the properties of each binder described above, the binder is mixed with an active material and a conductive agent to produce an electrode having desired electrode properties. When the electrode is configured to include such a polymeric material, the binder is formed in the electrode. It acts as a resistor or as a reactant, which can lead to a deterioration of the quality of the supercapacitor, such as high resistance or gas, resulting in poor reliability.

Therefore, it is preferable to use the minimum amount of the binder used to maintain the physical properties of the electrode material.

In general, the amount of the binder is preferably used in the range of 3wt% to 30wt% of the total electrode material (100wt% total), because the lower the binder content is less than 3wt%, the content of the conductive agent or active material relatively This increase can be expected to increase the short-term capacity, but because the electrode material is not effectively bound to the current collector, the electrode material layer collapses, and the capacity can be drastically reduced.

On the contrary, when the content of the binder exceeds 30wt%, the amount of the active agent that can express the capacity or the amount of the conductive agent that increases the electrical conductivity is relatively decreased, so that a desired amount of the capacity cannot be obtained.

However, since most of the binders mentioned above are used to increase physical properties such as binding properties rather than electrical properties such as conductivity or resistance, the larger the amount of the binder, the more the physical properties and the binding power with the current collector increases. However, the conductivity is lowered, the density of the active material is lowered, the resistance is increased and the capacity is reduced.

Therefore, when configuring the electrode material, the content of the active material, the conductive agent, and the binder should be determined in consideration of the physical properties such as the binding properties of the electrode layer and the current collector together with the electrical properties such as conductivity and capacity.

As such, the binder materials conventionally used are non-conductive polymer-based binders, which have high resistance (for example, PTFE conductivity = 10 ^-18 S / cm), causing an increase in the resistance of the electrode and decreasing the content of the active material. There was a problem to reduce the capacitance.

The use of a conventional electrode having such a problem can be a major cause of degrading the performance of the super capacitor as a whole.

Accordingly, an object of the present invention is to use a conductive carbon nanofiber (carbon nanofiber) in the manufacturing of the electrode as a binder to crosslink the active material and the conductive agent can increase the binding force and excellent electrical conductivity to improve the resistance It is to provide an electrode composition, an electrode, and a method for manufacturing the electrode for a super capacitor that can be reduced.

Another object of the present invention is to consider the fact that the larger the specific surface area in the mechanism of energy storage can obtain a large capacity, the carbon nanofibers having a large specific surface area as a binder, the electrode composition for a super capacitor that can increase the capacity To provide an electrode and a method of manufacturing the electrode.

In order to achieve the above object, according to an aspect of the present invention, an electrode active material made of a porous carbon material; Conductive agents for imparting conductivity; And an electrode composition for a super capacitor is provided comprising a binder containing carbon nanofibers.

According to another aspect of the invention, the current collector; And an electrode forming layer obtained by coating an electrode composition on the current collector, wherein the electrode forming layer comprises an electrode active material made of a porous carbon material, a conductive agent for imparting conductivity, and a binder containing carbon nanofibers. Provided is an electrode for a super capacitor, comprising an electrode composition.

According to another aspect of the invention, preparing a carbon nanofiber; Preparing an slurry by dissolving an electrode composition comprising an electrode active material made of a porous carbon material, a conductive agent for imparting conductivity, and a binder containing the carbon nanofibers in a solvent; And coating the slurry on a current collector to obtain an electrode forming layer on the current collector.

The active material may be activated carbon, and the conductive agent may be carbon black.

Preferably, the binder further comprises at least one of carboxy methyl cellulose (CMC) and styrene butadiene rubber (SBR).

The carbon nanofibers preferably contain 1 wt% to 10 wt% based on the total electrode composition.

 The length of the carbon nanofibers is preferably 5μm to 20μm.

Therefore, the present invention uses carbon nanofibers as a binder for weaving the active material and the conductive agent during electrode production, thereby increasing the binding force and reducing the resistance due to excellent electrical conductivity.

In addition, since the present invention contains a carbon nanofiber having a large specific surface area as a binder, the storage capacity can be increased.

In addition, the present invention can reduce the resistance because the electrical conductivity containing carbon nanofibers, which are relatively superior to the conventional binder as a binder.

The present invention is to produce an electrode containing carbon nanofibers as part of a binder. Carbon nanofibers, used as binders, have excellent electrical conductivity, reduce resistance, and have a diameter in nanometers, thereby increasing the specific capacitance of the electrode. In addition, since the carbon nanofibers have a length in micrometers, the binding force is improved by performing a crosslinking role between materials constituting the electrode.

The carbon nanofibers used in the present invention are manufactured through stabilization and carbonization using, for example, electrospinning on a nonwoven fabric. It is obtained by carbonization and grinding. At this time, the obtained carbon nanofibers have a diameter of approximately 500 nm and a length of approximately 10 μm.

According to the results of the present inventors, the diameter of the carbon nanofibers used as the binder in the present invention is preferably about several nanometers to several hundred nanometers in order to secure a specific surface area for achieving the function as a binder. In addition, the length of the carbon nanofibers is 5 μm or more, preferably 5 μm to 20 μm. When the length of the carbon nanofibers is less than 5 μm, crosslinking of the electrode material may not be performed sufficiently, resulting in breakage of the electrode, which is not preferable. On the other hand, if the length of the carbon nanofiber is too long, there is a problem in the process for producing the slurry is not preferable.

On the other hand, the amount of carbon nanofibers used in the present invention preferably contains 1wt% to 10wt% of the total electrode components. In other words, when the amount of carbon nanofibers added is less than 1wt%, it is difficult to substantially expect the effect of adding carbon nanofibers (resistance and increase of binding capacity). When the amount of carbon nanofibers exceeds 10wt%, the amount of the active material or the conductive agent is relatively small. Rather, it can lead to a decrease in dose.

Hereinafter, preferred embodiments of the present invention will be described in detail in comparison with comparative examples.

(Examples 1 to 6)

Activated carbon used as an active material (MSP-20, manufactured by kansai coke & chemicals, average particle 12 μm), carbon black (CB, average particle 40nm) as a conductive agent, carbon nanofiber (CNF), CMC and SBR To prepare an electrode material in the same ratio as in Examples 1 to 6 of Table 1, respectively, distilled water was mixed with 400wt% of the total electrode material in each solvent to prepare a slurry.

The prepared slurry was coated on an aluminum foil having an area of 1 × 1 cm 2. In this case, the electrolytes of Examples 1 to 6 commonly used 1M TEABF ₄ / ACN of Honeywell, which is commonly used in an electric double layer capacitor, and was simply prepared in a pouch type.

The electrodes prepared with the compositions of Examples 1 to 6 were each tested for electrochemical characteristics using cyclic voltammetry using a potentiometer M273A, and impedance was measured using PAR's VMC, and the results are shown in Table 1. .

(Comparative Example 1)

Activated carbon used as an active material (MSP-20, manufactured by kansai coke & chemicals, average particle size 12μm), carbon black (CB, average particle 40nm) as a conductive material, PTFE, CMC, SBR and PVP mixed binder The electrode material was prepared at the ratio shown in Table 1 below, and distilled water was mixed with 400 wt% of the total electrode material as a solvent to prepare a slurry.

The prepared slurry was coated on an aluminum foil having an area of 1 × 1 cm 2. At this time, the electrolyte was commonly used 1M TEABF ₄ / ACN of Honeywell (commonly used in the electric double layer capacitor) and was simply prepared in a pouch type (pouch type).

Here, the prepared electrode was confirmed the electrochemical characteristics by the same method as the above-described embodiments, and the impedance is measured and disclosed in Table 1 together.

(Comparative Example 2)

Comparative Example 2 excludes PTFE and PVP among the binders mixed in Comparative Example 1, and contains only CMC and SBR as binders, and thus the activated carbon, carbon black, and binders (CMC, SBR) are included in the ratio of the electrode material in Table 1. The electrode was prepared by preparing a slurry by mixing distilled water with 400 wt% of the total electrode material.

Here, the prepared electrode was confirmed the electrochemical characteristics by the same method as in Comparative Example 1 described above, it is shown in Table 1 by measuring the impedance.

Electrode Composition (wt%) Electrical characteristics bow
castle
burnt Carbon black CNF PTFE CMC SBR PVP
ESR
(mΩ) Capacity (mF / m ² ) SR50
(mv / s) SR100
(mv / s) SR1000
(mv / s) ratio
School
Yes One
79 12 - 3 2 3 One 1040.0 171.0 160.1 106.9 2
81 14 - - 2 3 - 780.0 181.1 178.9 111.9




room
city
Yes One
80 14 One - 2 3 - 598.0 207.0 197.6 140.0 2
84 9 3 - One 3 - 498.1 335.0 311.2 250.0 3
78 14 3 - 2 3 - 543.4 268.8 271.1 202.9 4
78 12 5 - 2 3 - 598.0 316.0 301.0 249.8 5
78 10 7 - 2 3 - 758.0 318.2 306.7 216.7 6
75 10 10 - 2 3 - 558.0 277.0 257.0 156.9

As shown in Table 1, the electrode manufactured with the composition of Example 1 had an equivalent series resistance (ESR) of 598.0 mΩ, and at scanning speeds (SR: scanning rate) of 50 mV / s, 100 mV / s, and 1000 mV / s. each ^{207.0mF / m 2, 197.6mF / m} 2. It has a capacity of 140.0 mF / m ² .

In addition, the electrode manufactured with the composition of Example 2 had an equivalent series resistance (ESR) of 498.1 mΩ, and 335.0 mF / m ² and 311.2 mF / m at scanning speeds of 50 mV / s, 100 mV / s and 1000 mV / s, respectively. ² . It has a capacity of 250.0 mF / m ² .

In addition, the electrode manufactured with the composition of Example 3 had an equivalent series resistance (ESR) of 543.4 mΩ, and 268.8 mF / m ² , 271.1 at scanning speeds (SR) of 50 mV / s, 100 mV / s, and 1000 mV / s, respectively. mF / m ² . It has a capacity of 202.9 mF / m ² .

In addition, the electrode manufactured with the composition of Example 4 had an equivalent series resistance (ESR) of 598.0 mΩ, and 316.0 mF / m ² , 301.0 at scanning speeds (SR) of 50 mV / s, 100 mV / s, and 1000 mV / s, respectively. mF / m ² . It has a capacity of 249.8 mF / m ² .

In addition, the electrode manufactured with the composition of Example 5 had an equivalent series resistance (ESR) of 758.0 mΩ, and 318.2 mF / m ² , 306.7 at scanning speeds (SR) of 50 mV / s, 100 mV / s, and 1000 mV / s, respectively. mF / m ² . It has a capacity of 216.7 mF / m ² .

In addition, the electrode manufactured with the composition of Example 6 had an equivalent series resistance (ESR) of 558.0 mΩ, and 277.0 mF / m ² and 257.0 at scanning speeds (SR) of 50 mV / s, 100 mV / s, and 1000 mV / s, respectively. mF / m ² . It has a capacity of 156.9 mF / m ² .

In Table 1, the electrode of Comparative Example 1 had an equivalent series resistance (ESR) of 1040.0 mΩ, and 171.0 mF / m ² and 160.1 mF at scanning speeds (SR) of 50 mV / s, 100 mV / s, and 1000 mV / s, respectively. / m ² . It has a capacity of 106.9 mF / m ² .

Comparative Example 2 is the electrode equivalent series resistance (ESR) indicates a 780.0mΩ, 50mV / s, 100mV / s, in 1000mV / s of a scan rate (SR) respectively ^{181.1mF / m 2, 178.9mF / m} 2. It has a capacity of 111.9 mF / m ² .

From the above results, Comparative Example 1 and Comparative Example 2 exhibited a high resistance characteristics of 1040.0mΩ and 780mΩ, respectively, whereas the Examples of the present invention exhibited a resistance characteristic of approximately 500mΩ lower than that, indicating that the resistance was significantly reduced. Can be.

In addition, it was confirmed that the capacity of the embodiments is relatively increased compared to the capacity of the comparative examples due to the reduced resistance.

On the other hand, in comparison with the comparative example and the embodiments of the present invention also in the dose reduction rate that appears as the scanning rate (SR) increases with such an increase in capacity, as shown in Table 1, the practice of the present invention is carried out. In the examples, the capacity reduction rate is markedly low, indicating that the life characteristics are excellent.

Referring to the above results, it was confirmed that the electrode manufactured by containing carbon nanofibers in the binder was able to obtain excellent electrode characteristics with low resistance and increased capacity as well as low capacity reduction rate.

While the present invention has been shown and described with reference to certain preferred embodiments, the present invention is not limited to the above-described embodiments, and the present invention is not limited to the spirit of the present invention, which is common in the art. Many changes and modifications will be possible to those skilled in the art.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electrode compositions for supercapacitors having excellent high capacitance and lifetime characteristics, electrodes, and methods of manufacturing the electrodes. And an electrode of the hybrid capacitor in which the EDLC and the pseudo capacitor are mixed.

Claims (14)

delete delete delete delete delete delete delete delete delete delete Preparing a carbon nanofiber by stabilizing the fiber obtained by electrospinning the nonwoven fabric in an air atmosphere at 300 ° C. and carbonizing in a vacuum atmosphere or an inert gas atmosphere at 950 ° C. and then grinding the fiber; Preparing an slurry by dissolving an electrode active material made of a porous carbon material, a conductive agent for imparting conductivity, and an electrode composition made of a binder containing the carbon nanofibers in a solvent; And Coating the slurry on a current collector to form an electrode forming layer on the current collector. The method of claim 11, wherein the binder A method of manufacturing an electrode for a super capacitor, characterized in that it further comprises at least one of CMC (carboxy methyl cellulose) and SBR (styrene butadiene rubber). The method of claim 11, wherein the carbon nanofibers contain 1 wt% to 10 wt% based on the total electrode composition. The method of manufacturing an electrode for a super capacitor according to claim 11 or 12, wherein the carbon nanofibers have a length of 5 μm to 20 μm.