KR20170047501A - Surface modification method of the carbon material electrode by conducting of joule-heating, a surface-modified carbon electrode thereof and electrochemical capacitors comprising the surface-modified material electrode - Google Patents

Abstract

The present invention relates to a method for modifying the surface of a carbon electrode by applying an electric current, a surface-modified carbon electrode, and an electrochemical capacitor including the surface-modified carbon electrode. The method for modifying the surface of a carbon electrode by applying an electric current comprises the steps of: preparing a carbon electrode; allowing a conductive terminal to contact the carbon electrode; and generating Joules heat by applying an electric current to the conductive terminal to remove an acidic functional group or adsorption water in the carbon electrode. Therefore, provided is an effect of removing the acidic functional group or adsorption water in a carbon pore of the carbon electrode in a short time by the Joules heat generated by directly applying the electric current to the carbon electrode manufactured by including a carbon material.

Description

TECHNICAL FIELD [0001] The present invention relates to an electrochemical capacitor including a surface-modified carbon material electrode, a surface-modified carbon material electrode, and a surface-modified carbon electrode modified electrochemical capacitors comprising the surface-modified material electrode < RTI ID = 0.0 >

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modifying the surface of a carbon material electrode by energization, a surface-modified carbon material electrode, and an electrochemical capacitor including the carbon material electrode. More particularly, A method of modifying the surface of a carbon material electrode by energization capable of removing functional groups or adsorbed water existing in the carbon material pores of the carbon material electrode in a short time by applying Joule's heat, To chemical capacitors.

Electric double layer capacitors (EDLC) and hybrid capacitors, which are one of the electrochemical capacitors, have advantages such as high output density, semi-permanent cycle characteristics, wide temperature range, There is an advantage that it is environment-friendly. Due to these advantages, it is a technology that is widely used as a power source in the fields of home appliances, portable communication devices, automobiles, and ESS (Energy Storage System). Electrochemical capacitors are composed of a mechanism for storing electric charge in an ion layer called an electric double layer formed at an interface between an electrode and an electrolyte, unlike a general battery using a chemical reaction.

Generally, the output capacity of the electrochemical capacitor is determined by the specific surface area of the electrode, the spacing between the electrodes, the pore distribution of the electrode, and the electrical conductivity of the electrode. That is, it is preferable to use an electrode material having such characteristics because the specific surface area of the electrode is large, the interval between the electrodes is narrow, the pore distribution of the electrode is uniform, and the electric conductivity of the electrode is high, . Therefore, carbon materials such as active carbon having high electrical conductivity, high electrochemical stability and low price, and graphene, which is being actively studied recently, are widely used as electrode materials .

The output capacity of electrochemical capacitors is most affected by the specific surface area of these carbon materials. However, long-term reliability characteristics of electrochemical capacitors such as charge / discharge life, leakage current, and self-discharge are influenced by the adsorbed water present in the functional groups and pores of the interface . For example, the acidic functional group on the surface of the carbonaceous material reacts with the electrolytic solution to generate propylene, hydrogen gas, and carbon dioxide gas as the applied voltage increases. They adversely affect the physical adsorption and desorption behavior of electrolyte ions on the surface of the carbonaceous material, which degrades the electrochemical capacitor's output capacity and long-term reliability. In order to solve this problem and improve the output capacity and long-term reliability of the electrochemical capacitor, there is a need for a surface modification technique that minimizes the functional groups or adsorbed water present on the surface of the carbon material.

As a surface modification technique for carbon materials, there is known a technique of heat treatment at a high temperature such as a carbon material for a capacitor electrode and a capacitor using the carbon material by chemical activation of NaOH according to the prior art 'Korean Patent Registration No. 10-1321523' A technique of removing an acidic functional group to easily remove adsorbed water or substituting with an inert functional group is known. This is problematic in that the total specific surface area is reduced by changing the pore structure of the activated carbon such that the micropores are closed as the heat treatment is performed at a high temperature for a long period of time.

Another prior art 'Korean Patent Application Laid-Open No. 10-2003-0010834' Plasma surface treatment apparatus and plasma surface treatment method using the same and 'Korean Patent Application Laid-open No. 10-2005-0106258' The plasma processing method and the like as shown in FIG. 1 are proposed. However, this method also has a problem that it is difficult to apply it to a mass processing technique because it is a treatment method using a minimum sample, so that it can not be easily used commercially.

Although the conventional techniques for surface-modifying the carbonaceous material have been known as described above, the technology for surface modification of the electrode manufactured through the carbon material requires further research and development.

Korea Patent Office Registration No. 10-1321523 Korean Patent Application Publication No. 10-2003-0010834 Korean Patent Application Publication No. 10-2005-0106258

Therefore, an object of the present invention is to provide a method for removing carbonaceous material or adsorbed water existing in a carbon material pore of a carbonaceous material electrode by applying electricity directly to a carbonaceous material electrode made of carbonaceous materials, A method for modifying the surface of a material electrode, a surface-modified carbonaceous electrode, and an electrochemical capacitor including a carbonaceous electrode.

The above object is achieved by a method of manufacturing a carbon nanotube electrode, comprising the steps of: preparing a carbon material electrode; Contacting the electrification terminal to the carbonaceous material electrode; And applying a current to the electrification terminal so as to remove an acidic functional group or adsorbed water present on the carbonaceous electrode to generate joule's heat, ≪ / RTI >

The step of contacting the energizing terminal may include a step of bringing the energizing terminal into contact with the left and right end portions along the width direction of the carbonaceous material electrode or contacting the energizing terminal to the upper and lower portions along the height direction of the carbonaceous material electrode, It is preferable to bring the current-carrying terminals into contact with each other.

The step of contacting the energizing terminal may include a step of laminating a plurality of the carbonaceous electrodes and bringing the energizing terminal into contact with the uppermost and lowermost portions along the height direction of the plurality of carbonaceous electrodes, It is preferable that the carbon material electrode is moved so that the first rolled roll is rotated and wound on the second rotating roll and a pair of energizing terminals are disposed on the moving path so that the carbon material electrode and the energizing terminal are in contact with each other .

It is preferable that at least one heater is provided around the carbon material electrode to heat the carbon material electrode.

The carbonaceous electrode is preferably in the form of a sheet obtained by kneading and rolling a carbonaceous material, a conductive material and a binder, and the carbonaceous material electrode is preferably laminated to the current collector by using a conductive adhesive.

Wherein the gas containing the nitrogen element is at least one selected from the group consisting of nitrogen (N ₂ ), nitrogen monoxide (NO), nitrogen dioxide (NO ₂ ), ammonia (NH ₃ ) , A gas obtained by heating a polymer containing a nitrogen element, and a mixture thereof.

Wherein the surface-modified carbon material further comprises 10 to 100 ppm / g of adsorbed water and 0.01 to 0.4 meq / g of a functional group, And the power density of the current is preferably 1 to 100 W / cm < 3 > so that the string current of 50 to 300 DEG C is generated.

The above object is achieved by a surface-modified carbonaceous electrode comprising a carbonaceous material, a conductive material and a binder, wherein the carbonaceous material is present in the pores of the carbonaceous material by using Joule's heat generated by the applied current Or a surface-modified carbonaceous electrode characterized by the removal of adsorbed water.

The above object is also achieved by an electrochemical capacitor comprising a cathode, an anode and an electrolytic solution, wherein at least one of the cathode and the anode is made of a carbon material electrode, and the carbon material electrode is formed by an applied current And an acidic functional group present in the pores or a carbonaceous material from which the adsorbed water is removed by using Joule's heat.

According to the structure of the present invention described above, electricity can be directly applied to the carbonaceous material including carbonaceous materials, thereby removing functional groups or adsorbed water existing in the carbonaceous material pores of the carbonaceous electrode in a short time by Joule's heat Lt; / RTI >

1 is a flowchart of a carbon material electrode surface modification method according to an embodiment of the present invention,
Fig. 2 is a plan view of the carbonaceous electrode according to the first to third embodiments in contact with the energizing terminal,
Figs. 3A and 3B are front views of the carbonaceous electrode according to the second and fourth embodiments,
Fig. 4 is a front view of a state in which a current-carrying terminal is in contact with a carbon material electrode according to a roll-to-roll method.

Hereinafter, an electrochemical capacitor including a carbon material electrode surface modification method by energization according to the present invention, a surface-modified carbon material electrode, and a carbon material electrode will be described in detail with reference to the drawings.

First, a carbon material electrode is prepared as shown in FIG. 1 (S1).

The carbon material electrode is an electrode including a carbon material powder, and is composed of a carbon material, a conductive material, and a binder. Electrodes may be produced after only the carbon material powder is energized. However, in order to minimize the moisture and acidic functional groups present in the carbon material pores and to simplify the process, it is effective to energize the carbon material in the electrode state.

Carbon materials include activated carbon, carbon black, graphite, graphene, hard carbon, carbon nano fiber, carbon nano tube, And a mixture thereof. Of these, activated carbon is most preferable.

Activated carbon is produced from phenol, petroleum pitch, coke and woody carbon materials by steam or alkali activation method. Acidic functional groups such as carbonyl, carboxyl, ketone and the like are introduced into the surface of activated carbon in the activation and cleaning process of activated carbon in general with metal impurities and these functional groups And adsorbs moisture to remain in the pores of the activated carbon. Although the acidic functional groups remaining in the pores help partially improve the wettability of the electrolytes, most of the functional groups and adsorbed water are likely to generate gas due to electrochemical irreversible reactions in electrolytes and pores or to form polymer deposits, And adsorption water should be minimized.

The carbon material used in the present invention has a specific surface area in the range of 10 to 5000 m < 2 > / g. If the specific surface area is less than 10 m < 2 > / g, it is difficult to generate Joule's heat due to the low electric resistance. If the specific surface area is too large, May occur. Therefore, the specific surface area should be in the range of 10 to 5000 m2 / g, more preferably 10 to 2500 m2 / g in order to minimize the change of the pore structure of the carbon material and to remove the acid functional group.

Examples of the conductive material include carbon black, graphite, graphene, hard carbon, carbon nano fiber, carbon nano tube, metal powder, and the like. And mixtures thereof, and it is preferable that the diameter is 0.01 to 10 탆. When the diameter of the conductive material is less than 0.01 탆, the conductivity may be deteriorated, and when it exceeds 10 탆, the conductive material may not be uniformly mixed with the carbon material.

The binder is most preferably polytetrafluoroethylene (PTFE). PTFE having a diameter of 0.1 to 0.5 占 퐉 may be used and may be used in a solid state alone or in a solid state in a solid state such as water (H ₂ O), xylene, methanol, ethanol, isopropanol, toluene Toluene, butyl acetate, and the like can be used in an emulsion state. Since PTFE has excellent chemical resistance, heat resistance and mechanical strength, the network structure of PTFE develops as the rolling is repeated to construct electrodes. As the network structure develops, the carbon material and the conductive material are adhered to each other, thereby increasing the filling density and reducing the contact resistance between the carbon material and the conductive materials, thereby improving the electrical characteristics of the electrode.

A carbon material, a conductive material and a binder are mixed to form a mixture, which is then kneaded and rolled to form a sheet-shaped carbon material electrode. The mixture may be kneaded using a ball mill or an impeller while maintaining a constant viscosity, and the mixture may be further mixed with a dispersion solvent if necessary.

As a method of manufacturing a carbon material electrode in the form of a sheet by rolling the mixture, a sheet is thinly rolled using a roll press, and then the sheet is folded and rolled again to form a plurality of rolls. This is because the binder, especially the PTFE fiber resin, is formed in the initial rolling to form a network structure, and as the rolling progresses repeatedly, the dense network structure of the PTFE fiber resin develops, thereby improving the electrical and mechanical characteristics of the electrode. The rolling is preferably repeated about 10 to 50 times, and it is possible to use a roll having the same upper and lower radii alone, or a method of controlling the thickness by rolling a plurality of rolls continuously.

The composition of the carbon material electrode is composed of 3 to 20 parts by weight of the conductive material and 2 to 10 parts by weight of the binder with respect to 100 parts by weight of the carbon material. The carbon material electrode preferably has an electrode density of 0.1 to 0.7 g / ml and a thickness of 30 to 250 占 퐉. When the conductive material is less than 3 parts by weight, the conductivity of the electrode is not good, and when the conductive material is more than 20 parts by weight, the proportion of other components is relatively low. When the amount of the binder is less than 2 parts by weight, the shape of the sheet can not be maintained properly. When the amount of the binder is more than 10 parts by weight, the content of the carbonaceous material and the conductive material is decreased. When the electrode density of the carbon material electrode is less than 0.1 g / ml, the conductivity is poor due to the low density. When the electrode density exceeds 0.7 g / ml, the density of the carbon material electrode may not be properly formed.

In some cases, the carbonaceous material electrode is bonded to the current collector (S1 ').

The sheet-shaped carbonaceous electrode produced in the step S1 may be laminated to the current collector. It is also possible to form a carbon material electrode directly on the current collector by coating a carbonaceous material slurry other than the sheet carbonaceous electrode. Here, the aluminum foil is most preferably used as the current collector, but the present invention is not limited thereto.

As a method of laminating a carbonaceous sheet, first, a sheet-like carbonaceous electrode is manufactured and then laminated with a current collector by using a conductive adhesive, thereby bonding to the current collector by such a method.

The conductive adhesive may be composed of a conductive material and a binder. The conductive material is selected from the group consisting of carbon black, hard carbon, graphite, graphene, carbon nanofiber, carbon nanotube, Al powder, Pt powder, Ni powder, Cu powder, Au powder, stainless steel powder, The average particle size of the powder having an aspect ratio of 0.5 or more is preferably 0.1 to 1 占 퐉, and the average particle size of the powder having a shape factor of less than 0.5 may be 1 to 20 占 퐉.

The binder may be selected from the group consisting of carboxymethylcellulose (CMC), polyvinylalcohol (PVA), polyvinylpyrrolidone (PVP), polyvinylidene fluoride (PVDF), methylcellulose (MC) , Polyacrylic acid (PAA), latex ethylene-vinyl chloride polymer, vinylidene chloride latex, chlorinated polymer, polyvinyl acetate Butadiene rubbers such as polyvinyl butyral, polyvinyl acetal, biphenol epoxy resin and styrene butadiene rubber (SBR), isoprene rubber, Butadiene rubber, isoprene rubber, nitrile butadiene rubber, urethane rubber, silicone rubber, acrylic rubber, It is selected from the group consisting of a mixture thereof is preferred.

The composition of the conductive adhesive may be composed of 5 to 50 parts by weight of binder based on 100 parts by weight of the conductive material based on the solid content. When the amount of the binder is less than 5 parts by weight, the content of the binder is insufficient, and the binder does not perform properly. When the amount of the binder is more than 50 parts by weight, the content of the conductive material is small. The conductive adhesive is mainly applied to current collectors made of aluminum foil, and the coating thickness can be adjusted within a range of 1 to 10 mu m.

In addition to the method of producing a sheet-like carbon material electrode and laminating it with a current collector, a carbon material electrode can also be manufactured by a method of directly coating a carbon material slurry on the current collector. At this time, it is preferable to use a current collector that is etched so that the carbonaceous material slurry can be easily coated.

The carbonaceous material slurry uses the conductive material and the binder used in the production of the carbonaceous electrode and adds a diluting solvent so as to have a viscosity lower than that of the carbonaceous material sheet. The mixed solution thus prepared is coated several times on the current collector so as to have a desired thickness to produce an electrode containing a carbon material.

The electrification terminal is brought into contact with the carbon material electrode (S2).

The current-carrying electrode is brought into contact with both ends of the carbonaceous material electrode or the carbonaceous material electrode bonded to the current collector so that current can be applied to the electrode. The method of bringing the current-carrying terminals into contact with the carbon material electrodes can be brought into contact with the left and right ends, respectively, along the width direction of the sheet-like carbon material electrode 110 as shown in Fig. This is because the current flows from the (+) terminal 131 to the (-) terminal 133 at the other end according to the first to third embodiments and the acidic functional group existing in the carbonaceous electrode 110 or The adsorbed water is removed.

3A is a front view showing a state in which the energizing terminal 230 is in contact with the upper and lower portions of the carbonaceous electrode 210 according to the fourth and fifth embodiments, respectively, (+) Terminal 231 provided on the carbonaceous material electrode 210 including the current collector 250 and the negative terminal 233 provided on the lower side. As shown in FIG. 3B, the plurality of carbon electrodes 210 may be laminated so that the plurality of carbon electrodes 210 are brought into contact with the upper and lower ends of the plurality of carbon electrodes 210 along the height direction. It is also possible to carry out the surface modification of the carbon material by flowing a current to the plurality of carbon material electrodes 210 arranged in such a shape at once.

4A and 4B illustrate a method for continuously reforming a sheet-like carbon electrode 310 when it is prepared in a large size. In this method, a carbon material electrode 310 is wound around a pair of rotating rolls 410 and 430 And the carbon material electrode 310 is surface-modified by a roll-to-roll method. As a method for surface-modifying the carbon material electrode 310 in a roll-to-roll fashion, a method is known in which a carbon material electrode 310 is wound on one first rotating roll 410 and rotated to another second rotating roll 430 The carbonaceous material electrode 310 is moved so that the carbonaceous material electrode 310 is wound and a pair of energizing terminals 330 are formed in the path between the pair of the rotating rollers 410 and 430, Is contacted with the carbon material electrode 310.

The contacted electrifying terminal 330 is disposed in the vicinity of the rotating roll 410 on which the carbonaceous electrode 310 is wound, It is preferable to dispose the terminal 333 so that a current flows along the direction in which the carbonaceous electrode 310 moves. 4, when the carbonaceous electrode 310 is moved, the rotating roll or the carbonaceous electrode 310 is allowed to pass without being rotated, But is not limited to, the shape of any one of a column, a half column, a rod, and a board.

Current is applied to the electrifying terminals 130, 230, and 330 to generate juxtaposition (S3).

The surface modification is performed by applying current to the carbon material electrodes 110, 210, and 310 through the current supply terminals 130, 230, and 330 that are in contact with the carbon material electrodes 110, 210 and 310. When an electric current is supplied to the carbon material electrodes 110, 210 and 310, resistance is generated by the contact resistance between the carbon material powders and the pore structure of the carbon material, and Joule's heat is generated in these carbon materials.

When a short circuit is generated due to the instantaneous power supply to the carbon material electrodes 110, 210 and 310, a rapid temperature change occurs and the acidic functional group or the adsorbed water can be easily removed in a short time. (CO), carbon dioxide (CO ₂ ), or hydrogen (CO ₂ ), which is present in the pores of the carbon material, carbon dioxide, carboxyl group or ketone group, H ₂ ) or the like and is discharged to the outside.

The current applied to the carbon electrodes 110, 210, and 310 may be either DC or AC, and may be applied to the carbon electrodes 110, 210, and 310, A string is generated. The power density of the current supplied here is preferably 1 to 100 W / cm < 3 > If the power density is less than 1 W / cm < 3 >, it is difficult to generate a desired number of joule heat. If the power density exceeds 100 W / cm < 3 >, the temperature may rise excessively and the shape of the carbon material pores in the carbon material electrode may change.

In the case of continuous surface modification of the carbonaceous electrode 310 shown in FIG. 4, the heat generated by the current may be insignificant compared to the temperature required for surface modification depending on the situation. Accordingly, a plurality of heaters 500 may be provided along the direction in which the carbon material electrode 310 moves. When the plurality of heaters 500 are installed as described above, there is an advantage that the effect of energization can be maximized. The heater 500 can maximize the effect of electric power by applying at least one heater 500 to the case of FIG. 2 and FIG. 3 as well as FIG. 4.

The method may further include the step of injecting gas into the carbon material electrodes 110, 210 and 310 in a step of applying a current to the carbon material electrodes 110, 210 and 310 to generate a joule heat.

When a gas containing nitrogen (N), hydrogen (H) and fluorine (F) elements is injected into the carbon material electrodes 110 and 210, the surface of the carbon material is filled with a hetero element such as nitrogen, hydrogen, ) Can be adsorbed. In the step of energizing the carbon material electrodes 110, 210 and 310, the acidic functional groups are removed by the joule heat, and when the gas is injected into the carbon materials, the carbon structure including the hetero element is formed in the pores of the carbon material.

For example, by passing a gas containing nitrogen (N) element, a carbon structure such as Pyrydone, Pyrrolic, Pyrydinic and Quaternary on the surface of the carbonaceous material . The carbon structure containing these nitrogen elements is adsorbed on the pores to inhibit the reformation of the acidic functional groups, increase the polarization and charge density of the carbonaceous material, inhibit deterioration with electrolyte ions, and increase the electric double layer capacity.

Here, the gas containing the nitrogen element includes nitrogen gas (N ₂ ), nitrogen monoxide (NO), nitrogen dioxide (NO ₂ ), ammonia (NH ₃ ), etc. These gases can be obtained by heating a polymer containing nitrogen . For example, when melamine (C ₃ N ₆ H ₆ ) is heated at 350 ° C or higher, it decomposes into carbon nitride (C ₃ N ₄ ) and -CN x and decomposes into nitrogen molecules And the nitrogen molecules are bound.

A gas containing nitrogen can be directly injected into the carbonaceous materials 110, 210 and 310 which are energized at a constant flow rate and can be mixed with hydrogen gas (H ₂ ) or argon gas (Ar). When nitrogen and nitrogen mixed gas is injected into the carbon material electrode, it is possible to bind nitrogen to the surface of the carbon material.

When a gas containing nitrogen is passed through the carbon material electrodes 110, 210 and 310, nitrogen per weight of the carbon material generally bonds with the carbon material within the range of 0.1 to 5%. Such weight parts may vary depending on the functional groups contained in the raw material of the carbonaceous material and the activation treatment of the carbonaceous material. That is, as the degree of graphitization of the carbonaceous raw material is smaller or the degree of activation is greater, the edge surface of the carbonaceous unit structure is more likely to be replaced with nitrogen. It is preferable that the raw material of the carbon material contains nitrogen in the range of 0.1 to 4 parts by weight in case of graphitization and 0.1 to 5 parts by weight in case of non-graphitizable property.

After the acidic functional groups or the adsorbed water are removed from the carbonaceous electrodes 110, 210, and 310, the carbonaceous materials 110, 210, and 310 having the carbonaceous material surface-modified are finally obtained (S4).

The surface-modified carbon material in the carbon material electrodes 110, 210 and 310 is finally formed to contain 10 to 100 ppm / g of adsorbed water and 0.01 to 0.4 meq / g of the acidic functional group. When the adsorption water is less than 10 ppm / g and the acidic functional group is less than 0.01 meq / g, the wettability of the carbon material pores is not good. When the adsorption water is more than 100 ppm / g and the acid functional group is more than 0.4 meq / g, It is not possible to increase the specific surface area of the carbon material because the amount of carbon is large.

If the surface of the carbonaceous material in the carbonaceous electrodes 110, 210 and 310 is reformed through the above steps S1 to S4, the surface modification is performed in a short time using the heat generated by energization to change the pore structure of the carbonaceous material Can be minimized. As a result, impurities such as acidic functional groups or adsorbed water contained in the pores are removed to increase the specific surface area of the carbon material, and the heat is applied in a short time, so that the pore distribution is uniform and unchanged. The electrochemical capacitors including the surface-modified carbon electrodes 110, 210 and 310 improve the output characteristics and increase the long-term reliability.

The density of the carbonaceous electrodes 110, 210, and 310 for the electrochemical capacitor according to the present invention is 0.1 to 0.7 g / ml, and the electrostatic capacity per electrode volume of the two- 25 F / ml, it can be used excellently in electrochemical capacitors, especially in electric double layer capacitors and hybrid capacitor electrodes.

The electrochemical capacitor is composed of an electrode composed of a cathode and an anode, and an electrolytic solution. Here, the electrode refers to a carbon material electrode 110, 210, 310 whose surface has been modified.

The type of the electrolytic solution of the electrochemical capacitor is not particularly limited, but is generally selected in consideration of the solubility, dissociation degree, viscosity of the solution, and the like, and an electrolytic solution having a high conductivity and a high potential difference is preferable. The electrolytic solution is preferably selected from the group consisting of a quaternary ammonium salt, a quaternary imidazolium salt, a quaternary pyridinium salt, a quaternary hosoponium salt, a quaternary spiroid salt and a mixture thereof. As a representative example, a quaternary ammonium salt such as Et ₄ NBF ₄ (Tetraethylammonium tetrafluoroborate) or Et ₃ MeNBF ₄ (Triethylmethylammonium tetrafluoroborate) is dissolved in an organic solvent such as PC (propylene carbonate) and AcN (Acetonitrile). Since the aqueous electrolytic solution has a low electrochemical decomposition voltage, the use voltage of the electrochemical capacitor is limited, so it is preferable to use an organic solvent electrolytic solution.

Hereinafter, specific experimental examples and comparative examples of the present invention will be described. However, it should be understood that the following examples are provided for the purpose of further illustrating the present invention and are not intended to limit the technical scope of the present invention.

<Manufacturing and energizing method>

(a) Production method of activated carbon electrode

1) The sheet was composed of activated carbon (2,000 m 2 / g, Kuraray Co.), carbon black and PTFE in a weight ratio of 85: 10: 5, followed by mixing and kneading, followed by roll- Lt; / RTI &gt;

2) Sheet-laminating electrode was prepared by applying a conductive adhesive agent (Acheson, Hitachi Chemical Co.) to an etching aluminum foil (20 탆, Korea JCC Co.) And adhered to one side or both sides of the sheet, and roll-leasing was performed at a roll surface temperature of 80 deg.

3) A slurry-coating electorde was prepared by mixing activated carbon (2,000 m 2 / g, Kuraray Co.), carbon black and a mixed binder (CMC: SBR = 40: 60 weight ratio) in an aqueous slurry (20 탆, JCC Co., Korea) was coated on both sides or both sides of an etching aluminum foil. The coated electrode was dried at 80 캜 and rolled to 80 캜 on a roll surface to prepare a slurry coated electrode having a thickness of 180 탆.

(b) Activation method of activated carbon electrode

1) The sheet was energized with a structure as shown in Fig. In FIG. 2, the current-carrying terminals 130 were brought into contact with both ends of the sheet 110 having a size of 2.5 × 2.5 cm 2, and then electricity was applied in the horizontal direction of the electrode surface under conditions of DC 50V, 2A. The atmosphere was maintained at a vacuum of 1 atm (760mHg) or more after the replacement with nitrogen, and the separation of the electrodes was performed after nitrogen was substituted at room temperature.

2) The sheet-laminating electrode was energized with a structure as shown in Fig. An electrode in which a sheet (2.5 x 2.5 cm 2) is attached to a cross section or both surfaces of a current collector 250 formed of an etching aluminum foil has a structure in which an energizing terminal 230 is brought into contact with upper and lower portions, Direction and DC 10V and 60A, respectively. The 20-layer sheet-attached electrode was energized under the conditions of DC 10V and 60A in the up-and-down direction of the electrode surface after bringing the energizing terminal 230 into contact with the upper and lower sides as shown in FIG. 3B. At the time of energization, the atmosphere was once substituted with nitrogen, and then a vacuum of 1 atm or more was maintained. The separation of the electrodes was performed after nitrogen was substituted at room temperature.

3) The slurry-coating electorde was energized with a structure as shown in Fig. A slurry coating (2.5 × 2.5 cm 2) electrode coated on one or both sides of a current collector 250 formed of an etching aluminum foil was prepared by bringing a current carrying terminal 230 into contact with upper and lower electrodes as shown in FIG. , And 60A. As shown in FIG. 3B, the 20-layer slurry coating electrode was energized in the condition of DC 10V and 60A in the up-and-down direction of the electrode surface after bringing the energizing terminal 230 into contact with the upper and lower sides. At the time of energization, the atmosphere was once substituted with nitrogen, and then a vacuum of 1 atm or more was maintained. The separation of the electrodes was performed after nitrogen was substituted at room temperature.

(c) Production of electric double layer capacitor cell

The sheet was attached to an etching aluminum foil as a current collector through a conductive adhesive agent (Acheson, Hitachi Chemical Co.), and the binding force was improved through a roll press maintaining a surface temperature of 150 ° C.

The sheet-attached electrode and the slurry-coated electrode were cut to 2.5 × 2.5 cm 2, and one end face of the current collector to which no electrode was attached was cut in the longitudinal direction and used as a terminal. Sectional carbon electrode / separator / cross-section carbon electrode] were laminated in this order using a sheet-attached electrode, a slurry-coated electrode, a separator (TF4035, Japan High Purity Industry Co., Ltd.) and a laminated polymer pouch Insert into the polymer bag. Then, an electrolyte solution in which 1.2 M of Et ₄ NBF ₄ was dissolved in acetonitrile (AcN) was impregnated and vacuum packed in an electrolyte injector capable of vacuum depressurization. In the polymer bag, a space for separating and removing gas that can occur at an applied voltage of the overvoltage is secured in advance.

<Measurement method>

(a) Measurement of electrode surface temperature during energization

The surface temperature of the electrode surface during the energization was measured by a thermal couple in contact with the electrode surface.

(b) 2.7V capacitance measurement

The electrostatic capacity of the electric double-layer capacitor cell was charged and discharged by a constant current method in a charge-discharge tester (MACCOR, Model MC-4). Charging and discharging of the electric double-layer capacitor cell in a temperature chamber maintaining the temperature of 25 ° C were charged from 0 to 2.7 V at a current density of 2 mA / cm 2 and then discharged to 0 V under the same conditions. The electrostatic capacity of the electric double layer capacitor cell was calculated by the following equation in the curve of the time-voltage in the tenth constant current discharge.

C (capacitance, F) = dt i / dV (1)

The electrostatic capacity per weight of activated carbon (F / g) is expressed by a value obtained by dividing the electrostatic capacity calculated by the above formula (1) by the weight of activated carbon of one electrode.

(c) AC resistance measurement

The internal resistance (ESR) of the electric double layer capacitor cell was measured by using an impedance analyzer (Zahner IM6) after charging and discharging 10 times. The internal resistance behavior was investigated in the frequency range of 100 kHz to 2.5 mHz, and the internal resistance (ESR) specified in the present invention showed an AC resistance value at 1 kHz.

(d) Capacity retention rate measurement at 3.5V

The 3.5V capacity retention rate of the electric double-layer capacitor cell was measured by a constant current method in a charge-discharge tester (MACCOR, Model MC-4). The electric double layer capacitor cell was charged and discharged from 0 to 3.5 V at a current density of 2 mA / cm 2 in a temperature chamber maintained at 40 ° C, and then charged to 3.5 V at the same current density and maintained for 100 hours. An electric double-layer capacitor cell with 100 hours elapsed under a 3.5 V charge state was discharged at the same current density, and the capacity retention rate (%) was calculated by the following formula.

Capacity retention rate (%) = (1st discharge capacity - discharge capacity after 100 hours passed) / 1st discharge capacity 占 100 (2)

&Lt; Example 1 >

The sheet having a size of 2.5 x 2.5 cm 2 was energized for 2 minutes at DC 50V, 2A in a direction parallel to the electrode surface. The electrode was attached to the end face of the etched aluminum using a conductive adhesive agent, and the cell was constituted of 'Electrode having a conductive sheet / separator / energized sheet', and impregnated with an electrolyte in which 1.2 M of Et ₄ NBF ₄ was dissolved in AcN . The surface temperature at the time of sheet activation was 120 ° C, and the non-capacity and 1 kHz resistance at AC of 2.7 V for the cell were 121 F / g and 86 mΩ, respectively. Also, the capacity retention rate obtained from the 3.5 V aging test of the cell was 67%.

&Lt; Example 2 >

The sheet having a size of 2.5 x 2.5 cm 2 was subjected to DC 50 V, 2A for 4 minutes in a direction parallel to the electrode surface. The electrode was attached to the end face of the etched aluminum using a conductive adhesive agent, and the cell was constituted of 'Electrode having a conductive sheet / separator / energized sheet', and impregnated with an electrolyte in which 1.2 M of Et ₄ NBF ₄ was dissolved in AcN . The surface temperature of the sheet was 150 ° C. The capacitance of the cell at 2.7V and the 1kHz resistance at AC were 121F / g and 85mΩ, respectively. Also, the capacity retention rate obtained from the 3.5 V Aging test of the cell was 75%.

&Lt; Example 3 >

The sheet having a size of 2.5 x 2.5 cm 2 was supplied to the electrode surface in a horizontal direction at DC 50V, 2A for 5 minutes. The electrode was attached to the end face of the etched aluminum using a conductive adhesive agent, and the cell was constituted of 'Electrode having a conductive sheet / separator / energized sheet', and impregnated with an electrolyte in which 1.2 M of Et ₄ NBF ₄ was dissolved in AcN . The surface temperature of the sheet was 180 ° C. The capacitance of the cell at 2.7V and the 1kHz resistance at AC were 121F / g and 79mΩ respectively. Also, the capacity retention rate obtained from the 3.5V Aging test of the cell was 85%.

<Example 4>

Twenty layers of sheet-attached electrodes having a 2.5-by-2.5 cm2 size sheet adhered to the end face of an etching aluminum foil were stacked and then energized for 5 minutes at DC 10V and 60A in the vertical direction of the electrode surface. The cell was constituted of an electrode with a conductive sheet and an electrode with a conductive sheet using only one anode of the first layer and a negative electrode of the first layer, and impregnated with an electrolyte in which 1.2 M of Et ₄ NBF ₄ was dissolved in AcN. The sheet surface had a surface temperature of 150 ° C when the electrode was energized. The capacitance of the cell at 2.7 V and the 1 kHz resistance at AC were 125 F / g and 72 mΩ, respectively. Also, the capacity retention rate obtained from the 3.5 V Aging test of the cell was 80%.

&Lt; Example 5 >

Twenty layers of 2.5 × 2.5 cm 2 sheets were laminated, and then electricity was applied for 6 minutes at DC 10V and 60A in the vertical direction of the electrode surface. The cell was constituted of an electrode with a conductive sheet and an electrode with a conductive sheet using only one anode of the first layer and a negative electrode of the first layer, and impregnated with an electrolyte in which 1.2 M of Et ₄ NBF ₄ was dissolved in AcN. The sheet surface had a surface temperature of 150 ° C during the energization of the sheet, and the non-capacity and 1 kHz resistance at AC of 2.7 V for the cell were 115 F / g and 75 mΩ, respectively. Also, the capacity retention rate obtained from the 3.5 V Aging test of the cell was 75%.

&Lt; Comparative Example 1 &

An electrode with a sheet in which a sheet having a size of 2.5 × 2.5 cm 2 was adhered to the end face of an etching aluminum foil with a conductive adhesive constituted a cell with a sheet electrode / separator / sheet electrode together with a separator. These combinations were vacuum dried for 12 hours in a vacuum desiccator maintained at 150 占 폚. Then, an electrolytic solution in which 1.2 M of Et ₄ NBF ₄ was dissolved in AcN was impregnated to prepare an electric double layer capacitor cell. The capacitance of the cell at 2.7V and the 1kHz resistance at AC were 121F / g and 92mΩ, respectively. Also, the capacity retention rate obtained from the 3.5V Aging test of the cell was 45%.

&Lt; Comparative Example 2 &

A 2.5 × 2.5 cm 2 slurry cross-section coated electrode was fabricated with a slurry-coated electrode / separator / slurry-coated electrode along with a separator. These combinations were vacuum dried for 12 hours in a vacuum desiccator maintained at 150 占 폚. Then, an electrolytic solution in which 1.2 M of Et ₄ NBF ₄ was dissolved in AcN was impregnated to prepare an electric double layer capacitor cell. The capacitance of the cell at 2.7V and the 1kHz resistance at AC were 121F / g and 92mΩ, respectively. Also, the capacity retention rate obtained from the 3.5V Aging test of the cell was 35%.

Table 1 shows the results of the experiments of Examples and Comparative Examples.

Electrode state
Conduction direction Electrode surface temperature (캜) 2.7V test 3.5V test Non-capacity
(F / g) resistance
(mΩ) Volume
Retention rate (%) Example 1 Sheet Electrode face
level 120 121 86 67 Example 2 Sheet Electrode face
level 150 121 85 75 Example 3 Sheet Electrode face
level 180 121 79 85 Example 4 Sheet-attached electrode Electrode face
level 150 125 72 80 Example 5 Slurry coating electrode Electrode face
level 150 115 75 75 Comparative Example 1 Sheet-attached electrode Electrode face
level - 121 92 45 Comparative Example 2 Slurry coating electrode Electrode face
level - 115 95 35

Here, when 2.7V test was discharged at a current density of 2 mA / cm 2 at 2.7 V, the 3.5 V test was conducted at a current density of 2 mA / cm 2 for 100 h at 40 캜, and the capacity retention ratio relative to the initial 3.V discharge capacity was indicated .

It can be seen that the electrode surface temperature rises as the energization time increases in Examples 1 to 3 in which the sheet is horizontally energized on the electrode surface. In Example 3, the electrode surface temperature was increased to 180 ° C. As the surface temperature of the electrode increased, the internal resistance of the cell decreased and the capacity retention ratio increased to 85% in the 3.5V Aging test. On the other hand, the cell internal resistances of the electrode with the sheet of Example 4 and the slurry coated electrode of Example 5, which were energized to the top and bottom of the electrode surface, reached 72 ° C and 75mΩ respectively, The retention ratios were 80% and 75%, respectively. These values show excellent electrochemical characteristics as compared with the sheet-attached electrode of Comparative Example 1 and the slurry-coated electrode of Comparative Example 2, which are generally dried and assembled in a vacuum oven.

From these results, it can be seen that when the carbon electrode is energized horizontally or vertically on the electrode surface, the increase in the specific capacity (F / g), the decrease in the internal resistance of the cell, the capacity retention rate It can be seen that the change of the characteristic is increasing.

This means that it is easy to remove the acidic functional groups and adsorbed water present in the active carbon pores of the active material of the carbon electrode through energization and that the electrochemical characteristics of the electric double layer capacitor are improved by suppressing the side reaction of the activated carbon and the electrolyte by energization do.

In the method for modifying the surface of the carbonaceous material electrode after the carbonaceous electrodes 110 and 210 are fabricated, the surface of the carbonaceous material is modified within a short time due to generation of the joule heat. Therefore, The acidic functional group can be efficiently removed in a short time as compared with the modification method and the electrochemical capacitor using the same is a useful method for improving the capacity retention rate while minimizing the sacrifice of the capacity. Accordingly, the carbonaceous electrodes 110 and 210 and the capacitor manufactured through such a method exhibit higher output characteristics than conventional electrodes and capacitors.

110, 210, 310: carbonaceous material electrode
130, 230, 330: Energizing terminal
131, 231, 331: (+) terminal
133, 233, 333: (-) terminal
250: The whole house
410: first rotating roll
430: second rotating roll
500: heater

Claims (20)

In a carbon material electrode surface modification method using energization,
Preparing a carbonaceous material electrode;
Contacting the electrification terminal to the carbonaceous material electrode;
And applying a current to the electrification terminal so as to remove an acidic functional group or adsorbed water present on the carbonaceous electrode to generate joule's heat, Modification method. The method according to claim 1,
Wherein the step of contacting the energizing terminal comprises:
And the current-carrying terminals are brought into contact with the left and right ends along the width direction of the carbonaceous material electrode, respectively. The method according to claim 1,
Wherein the step of contacting the energizing terminal comprises:
And the conductive terminals are brought into contact with the upper and lower portions of the carbonaceous material electrode along the height direction of the carbonaceous material electrode. The method according to claim 1,
Wherein the step of contacting the energizing terminal comprises:
Wherein the plurality of carbonaceous electrodes are laminated and the energizing terminal is brought into contact with the uppermost and lowermost portions along the height direction of the plurality of carbonaceous electrodes. The method according to claim 1,
Wherein the step of contacting the energizing terminal comprises:
The carbon material electrode is moved so that the first rotating roll on which the carbonaceous material electrode is wound is rotated and wound on the second rotating roll, and a pair of energizing terminals are disposed on the moving path so that the carbonaceous material electrode and the energizing terminal Wherein the carbon nanotubes are brought into contact with each other. 6. The method of claim 5,
Wherein the electrifying terminal is formed in any shape of a rotary roll, a column, a half column, a rod, and a board. The method according to claim 1,
The step of generating the string-
Wherein at least one heater is provided around the carbon material electrode to heat the carbon material electrode. The method according to claim 1,
The carbon material electrode
A method for modifying a carbonaceous material electrode surface by energization, characterized in that the carbonaceous material is a sheet shape obtained by kneading and rolling a carbon material, a conductive material and a binder. 9. The method of claim 8,
The sheet-like carbonaceous material electrode has,
Wherein the current collector is laminated to the current collector using a conductive adhesive agent. 9. The method of claim 8,
The carbonaceous electrode has an electrode density of 0.1 to 0.7 g / ml,
Wherein the carbonaceous material electrode has a thickness of 30 to 250 占 퐉. The method according to claim 1,
The carbon material electrode
A method for modifying a carbonaceous material electrode surface by electrification, wherein the carbonaceous material electrode surface is formed by coating a carbonaceous material slurry obtained by mixing a carbonaceous material, a conductive material and a binder on a current collector. The method according to claim 1,
Wherein the step of generating juxtaposition comprises:
Wherein the heating is performed in a gas atmosphere containing a nitrogen element. 12. The method of claim 11,
The gas containing the nitrogen element may be,
A gas obtained by heating a polymer containing nitrogen (N ₂ ), nitrogen monoxide (NO), nitrogen dioxide (NO ₂ ), ammonia (NH ₃ ) and nitrogen element and mixtures thereof. A method for modifying the surface of a carbon material electrode. The method according to claim 1,
After the step of generating joule heat,
Further comprising the step of obtaining the carbonaceous material having the surface modified carbonaceous material,
Wherein the surface-modified carbon material comprises 10 to 100 ppm / g of adsorbed water and 0.01 to 0.4 meq / g of a functional group. The method according to claim 1,
Wherein the power density of the current is in the range of 1 to 100 W / cm &lt; 3 &gt; so that the string current of 50 to 300 DEG C is generated. 16. The method of claim 15,
Wherein the current is either a direct current or an alternating current. The method according to claim 1,
Wherein the carbonaceous material has a specific surface area of 10 to 5000 m &lt; 2 &gt; / g. The method according to claim 1,
The carbon material,
Carbon black, graphite, graphene, hard carbon, carbon nano fiber, carbon nanotube, carbon nanotube, carbon nanotube, Powder, and a mixture thereof. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt; A surface-modified carbonaceous electrode comprising a carbonaceous material, a conductive material and a binder,
Wherein the carbonaceous material is an acidic functional group or an adsorbed water present in pores of the carbonaceous material by using Joule's heat generated by an applied current. In an electrochemical capacitor including a negative electrode, a positive electrode, and an electrolytic solution,
Wherein at least one of the cathode and the anode is made of a carbon material electrode,
Wherein the carbonaceous electrode comprises an acidic functional group existing in pores or a carbonaceous material from which adsorbed water is removed by using Joule's heat generated by an applied current.

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