KR101932966B1 - Super capacitor and method for manufacturing the same - Google Patents

Super capacitor and method for manufacturing the same Download PDF

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Publication number
KR101932966B1
KR101932966B1 KR1020160161100A KR20160161100A KR101932966B1 KR 101932966 B1 KR101932966 B1 KR 101932966B1 KR 1020160161100 A KR1020160161100 A KR 1020160161100A KR 20160161100 A KR20160161100 A KR 20160161100A KR 101932966 B1 KR101932966 B1 KR 101932966B1
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South Korea
Prior art keywords
activated carbon
binder
electrode
current collector
metal
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KR1020160161100A
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Korean (ko)
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KR20180061670A (en
Inventor
허진우
이문배
임창건
조진익
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삼신디바이스 주식회사
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/66—Current collectors
    • H01G11/68—Current collectors characterised by their material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/22—Electrodes
    • H01G11/30—Electrodes characterised by their material
    • H01G11/32—Carbon-based
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G11/00—Hybrid capacitors, i.e. capacitors having different positive and negative electrodes; Electric double-layer [EDL] capacitors; Processes for the manufacture thereof or of parts thereof
    • H01G11/84—Processes for the manufacture of hybrid or EDL capacitors, or components thereof
    • H01G11/86—Processes for the manufacture of hybrid or EDL capacitors, or components thereof specially adapted for electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/13—Energy storage using capacitors

Abstract

The present invention relates to an ultra-high capacity capacitor and a method of manufacturing the same. The present invention relates to a positive electrode; cathode; Electrolytic solution; And a separator interposed between the anode and the cathode, wherein at least one selected from the anode and the cathode has a metal current collector and an activated carbon electrode formed on the metal current collector, And a metal oxide film layer formed by oxidation on the surface to be bonded, and a method of manufacturing the same. According to the present invention, a metal oxide film layer is formed on a metal current collector in contact with an activated carbon electrode, and has excellent electrical characteristics such as a high capacity. In addition, it has excellent electrical properties and long-term reliability.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a super capacitor,

The present invention relates to a super capacitor and a method of manufacturing the same. According to one embodiment, the contact area between the electrode (active material) and the metal current collector is improved, and the electrical characteristic such as the capacitance To an improved super-high capacity capacitor and a manufacturing method thereof.

Super Capacitor such as Electric Double Layer Capacitor (EDLC) or Lithium Capacitor (LiC) as an electrochemical device has a higher energy density than other general secondary batteries, Demand is high because the deterioration due to repetition is small, requiring little repair.

Therefore, supercapacitor is mainly used as auxiliary power supply for various electric and electronic devices, IC backup power supply, etc. Recently, toys, industrial power supply, uninterruptible power supply (UPS), solar energy storage, HEV / EV SUB POWER Has been widely applied.

In general, a super-high capacity capacitor such as an electric double layer capacitor (EDLC) has two electrodes (polarized electrodes) of positive and negative electrodes and a pair of electrodes interposed between the two electrodes to allow only ion conduction, A separator made of a porous material, and an electrolyte solution impregnated with the positive and negative electrodes to conduct ions. In this case, the positive electrode and the negative electrode may be the same or different from each other depending on the kind of the ultra-high capacity capacitor, and in most cases, they include porous activated carbon. Specifically, most super-capacity capacitors are mainly manufactured by coating at least one of the positive electrode and the negative electrode with an activated carbon electrode composition (electrode active material) coated on a metal current collector such as an aluminum foil .

Activated carbon has a high specific surface area and is useful as an electrode material for electric double layer capacitors (EDLC) and the like. For example, the capacitance of the electric double layer capacitor (EDLC) is determined by the amount of charge accumulated in the electric double layer, and the amount of the electric charge is increased as the specific surface area of the electrode is larger. Accordingly, the activated carbon having the porous structure has a high specific surface area, so that the capacity of the electrode can be increased and the energy density can be improved.

Generally, activated carbon is produced by carbonizing a carbon raw material (carbon precursor) at a high temperature and then activating the carbon precursor into a porous structure. At this time, in the activation step, an alkali activating agent such as potassium hydroxide (KOH) is mixed mainly with the carbon raw material, and then heated in an inert gas atmosphere to cause alkali metal to penetrate between the carbon crystal layers and react to form micropores . The activated carbon obtained by such alkali activation has a large specific surface area and uniform particle size, and is useful as an electrode material of an electric double layer capacitor (EDLC). For example, Japanese Patent Application Laid-Open No. 2009-260177 and Japanese Patent Application Laid-Open No. 2010-245482 disclose techniques related to this.

Activated carbon is also widely used as a raw material for carbon, which is activated by phenol resin, activated by coconut shell (coconut shell), apricot seeds and rice hull. For example, Korean Patent No. 10-0348499 discloses a method for producing activated carbon using rice hulls, and Korean Patent No. 10-0342069 discloses a method of mixing a binder and the like in rice hull activated carbon, A method of manufacturing an electrode is disclosed. Korean Patent No. 10-1105715 discloses a method for producing an electrode using phenol resin-based activated carbon and coconut shell-based activated carbon.

Generally, most of the activated carbon has a high content of impurities and the like, resulting in low resistance characteristics. Accordingly, in manufacturing an electrode of the electric double layer capacitor (EDLC), an electrically conductive conductive material is added to activated carbon. Specifically, an activated carbon electrode composition is obtained by mixing a particulate activated carbon, a particulate conductive material for electrically connecting activated carbon particles, and a binder for binding them, and then coating the same on the metal current collector, And rolled to manufacture an electrode. At this time, carbon black or the like is mainly used as the conductive material. By the addition of the conductive material, the electric conductivity can be improved and the resistance characteristic can be improved. As the metal current collector, an etching foil in which a thin metal film such as aluminum (Al) is etched is mainly used. The etch foil can improve the surface area of the electrode.

However, the electric double layer capacitor (EDLC) according to the prior art has a low capacity. For example, when a large amount of conductive material is added to improve the resistance characteristic, the content of activated carbon is relatively low, and it is difficult to show a high capacitance. Further, the electric double layer capacitor (EDLC) according to the prior art has low long-term reliability. Specifically, the electric double layer capacitor (EDLC) according to the related art has a problem that the long-term reliability such as a drop in capacitance and an increase in resistance due to an increase in the internal pressure or deterioration of the electrode becomes lower as the use time increases. In addition, it is difficult to obtain a high operating voltage due to an increase in internal pressure or the like.

On the other hand, almost all electronic products including products such as IC and backup power supply have an operating voltage of 1.8V or more, and advantageously, 3V or more. Highly, it requires use in a wide voltage range up to 48V for electric vehicles. Accordingly, in a product requiring a high voltage, two or more unit cells are connected in series to increase the operating voltage to at least 5 V. For example, in industrial devices, electric vehicles and UPS, 100 unit cells are packed in series / parallel so that a voltage of 10V to 48V is driven.

However, when two or more unit cells are connected in series to increase the operating voltage of the electric double layer capacitor (EDLC), there is another problem that must solve the balance problem between each unit cell that necessarily occurs. Specifically, in consideration of the capacity of the unit cell, the equivalent series resistance (ESR), the leakage current, and the like, the voltage balance of the resistor, diode, and other ICs is adjusted so that the entire operating voltage of the electric double layer capacitor A protection circuit is required. In this case, moreover, in order to provide a margin of the total operating voltage, the above packaging should also be designed by adding at least one unit cell so that the total voltage distribution is much lower than the operating voltage of each unit cell.

Also, the energy storage amount, which is one of the data relating to the energy storage, is a good index for comparing the amount of energy in the case of an electric double layer capacitor (EDLC) like a general secondary battery. At this time, the energy storage amount can be obtained by the following equation.

Energy storage amount (J) = 1 / 2CV 2

(Where C is the cell's capacitance (F) and V is the voltage).

As shown in the above equation, the energy storage amount is proportional to the capacitance (C), but is proportional to the square of the voltage (V). For example, doubling the capacity increases the energy storage by a factor of two, but doubling the voltage increases the energy storage by a factor of four. Therefore, the best way to increase the maximum amount of energy of the electric double layer capacitor (EDLC) is to increase the operating voltage (V).

However, a conventional electric double layer capacitor (EDLC) has a low operating voltage (V), and thus it is difficult to show a high energy storage amount. For example, a cylindrical electric double layer capacitor (EDLC) has a low operating voltage (V) in the range of 2.3 to 2.5V. Accordingly, most of the conventional electric double layer capacitors (EDLC) have a problem that at least two or more electric double layer capacitors (EDLC) are connected in series when they are applied to products such as ICs. Also, in this case, the volume of the electric double layer capacitor (EDLC) installed on the printed circuit board (PCB) is increased, which makes it difficult to miniaturize the electric / electronic product.

Japanese Laid-Open Patent Application No. 2009-260177 Japanese Laid-Open Patent Application No. 2010-245482 Korean Patent No. 10-0348499 Korean Patent No. 10-0342069 Korean Patent No. 10-1105715

Accordingly, it is an object of the present invention to provide an ultra-high capacity capacitor having improved characteristics and a manufacturing method thereof. According to one embodiment of the present invention, there is provided an ultra-high capacity capacitor having a low resistance and a high capacitance, and a manufacturing method thereof.

According to an aspect of the present invention,

anode;

cathode;

Electrolytic solution; And

And a separator interposed between the positive electrode and the negative electrode,

At least one selected from the positive electrode and the negative electrode,

A metal current collector, and an activated carbon electrode formed on the metal current collector,

And the metal current collector includes a metal oxide layer formed by oxidation on the surface of the metal current collector joined to the activated carbon electrode.

According to a preferred embodiment, the activated carbon electrode includes activated carbon, a binder and a conductive material, wherein the binder includes carboxymethylcellulose and a butadiene-styrene-alkyl methacrylate copolymer.

Further, according to the present invention,

Preparing an anode;

Preparing a cathode;

Obtaining a laminate including a separator between the anode and the cathode; And

Impregnating the laminate with an electrolytic solution,

Wherein the step of preparing the positive electrode and the step of preparing the negative electrode comprise:

A) a step (a) of immersing the metal current collector in an electrolytic aqueous solution and then forming the metal current collector on the surface of the metal current collector by applying a voltage to the positive electrode (+); And

And b) forming an activated carbon electrode on the metal oxide film layer.

According to a preferred embodiment, in the step a) of forming the metal oxide film layer, an electrolytic aqueous solution containing perchloric acid (HClO 4 ) and oxalic acid (C 2 H 2 O 4 ) is used as the electrolytic aqueous solution, It is preferable to form a metal oxide film layer having a thickness of 10 nm or less.

According to a preferred embodiment, in the step b) of forming the activated carbon electrode, an activated carbon electrode composition comprising activated carbon, a binder and a conductive material is used, and examples of the binder include carboxymethyl cellulose and butadiene-styrene-alkyl methacrylate It is preferable to use a binder containing a copolymer.

According to the present invention, an ultra-high capacity capacitor having improved characteristics and a method of manufacturing the same are provided. According to the present invention, for example, there is an effect that a metal oxide film layer is formed on a metal current collector in contact with an activated carbon electrode to have a high capacity.

Further, according to the present invention, it is possible to realize excellent long-term reliability with excellent electrical characteristics.

1 is a manufacturing process diagram of an ultra-high capacity capacitor according to an exemplary embodiment of the present invention.
FIG. 2 is a cross-sectional view of a metal current collector constituting an ultra-high capacity capacitor according to the present invention and a manufacturing process of the electrode.
3 is a graph showing the results of evaluation of interlaminar adhesive strength of an electrode sheet according to Examples and Comparative Examples of the present invention.
4 is a graph showing a capacity retention rate (%) according to a discharge rate ([C]) of an EDLC cell according to an embodiment and a comparative example of the present invention.
FIG. 5 is a graph showing a capacity retention rate (%) according to a cycle number of an EDLC cell according to an embodiment of the present invention and a comparative example.
6 is a graph showing resistance increase rate (%) of an EDLC cell according to Examples and Comparative Examples of the present invention with time.
7 is a graph showing the result of evaluating the interlaminar adhesion of the electrode sheet according to the embodiment of the present invention.

As used herein, the term "and / or" is used to mean at least one of the elements listed before and after. The term "one or more" as used herein means one or more than two. In this specification, terms such as " first "and" second "are used to distinguish one element from another, and each element is not limited to these terms.

In the present specification, the terms "forming on top of "," forming on top ", "installing on top ", and" mounting on top "do not mean only that the components are directly laminated And includes the meaning that another component is formed (installed) between the components. For example, "formed on" And "mounted on" means not only that the second component is formed directly in contact with the first component, but also a third component between the first component and the second component It also includes a meaning that can be further formed (installed).

An ultra-high capacity capacitor according to the present invention includes: a positive electrode; cathode; Electrolytic solution; And a separator interposed between the anode and the cathode, wherein at least one selected from the anode and the cathode comprises a metal current collector and an activated carbon electrode formed on the metal current collector. At this time, the metal current collector includes a metal oxide layer formed by oxidation on a surface bonded to the activated carbon electrode.

Also, a method of manufacturing an ultra-high capacity capacitor according to the present invention includes: preparing a cathode; Preparing a cathode; Obtaining a laminate through a separator between the anode and the cathode; And impregnating the laminate with an electrolytic solution. At least one of the steps of preparing the positive electrode and preparing the negative electrode may be a step of immersing the metal current collector in an electrolytic aqueous solution and then applying the voltage to the metal current collector as a positive electrode, A) forming a metal oxide film layer on the surface of the metal current collector; And b) forming an activated carbon electrode on the metal oxide film layer.

According to the present invention, it has at least a high capacity characteristic. That is, according to the present invention, at least the electrostatic capacity is improved. According to one embodiment, the capacitance (high capacity characteristic) is improved by the metal oxide film layer formed on the metal current collector. According to another embodiment, the capacitance (high capacity characteristic) is improved also by the configuration of the activated carbon electrode or the like. Further, according to the present invention, electrical characteristics such as resistance and / or high voltage characteristics are improved, lifetime characteristics are improved, and long-term reliability is obtained.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate exemplary embodiments of the invention and are provided to aid in the understanding of the invention only. In the following description of the exemplary embodiments of the present invention, detailed descriptions of commonly known general functions and / or configurations are omitted.

Fig. 1 is a block diagram (manufacturing process diagram) of an ultra-high capacity capacitor according to an exemplary embodiment of the present invention. FIG. 2 is a cross-sectional view of a metal current collector constituting an ultra-high capacity capacitor according to the present invention and a process of manufacturing the electrode.

Hereinafter, an embodiment of an ultra-high capacity capacitor according to the present invention will be described with reference to an electric double layer capacitor (EDLC). However, the ultra high capacity capacitor according to the present invention is not limited to the electric double layer capacitor (EDLC), and it is an electrochemical device for storing energy such as lithium ion capacitor (LiC), pseudo capacitor (pseudo capacitor) and hybrid capacitor Hybrid capacitors), lithium ion secondary batteries, lithium polymer batteries, and the like.

The term "electrical characteristic" used in the present invention means at least one or more selected from the capacity, energy density, voltage, resistance and leakage current of the super-high capacity capacitor. For example, "electrical characteristics are improved (improved)" means that at least one selected from the capacity, energy density, voltage, resistance, and leakage current of a supercapacitor is excellent .

Referring first to FIG. 1, an electric double layer capacitor (EDLC) according to the present invention includes at least one anode 10; At least one cathode (20); At least one separator (30); And an electrolytic solution. The separator 30 is sandwiched between the positive electrode 10 and the negative electrode 20. The electric double layer capacitor (EDLC) according to the present invention includes a stacked body 100 in which an anode 10 and a cathode 20 are alternately stacked with a separator 30 interposed therebetween, 100). The positive electrode 10 and the negative electrode 20 are impregnated with the electrolytic solution.

In the present invention, the number of the positive electrode 10, the negative electrode 20, and the separator 30 is not limited. In addition, the electric double layer capacitor (EDLC) according to the present invention can be selected from a cylindrical (winding) type, a rectangular type (box type), a coin type, and a pouch type, and the shape and kind thereof are not particularly limited.

Figure 1 illustrates a cylindrical electric double layer capacitor (EDLC). 1, the laminate 100 including the positive electrode 10, the negative electrode 20 and the separator 30 is wound in a cylindrical shape and then subjected to banding ). The positive and negative electrodes 15 and 25 are formed on the anode 10 and the cathode 20 respectively and a part of the terminals 15 and 25 may be drawn out.

The laminate 100 may be embedded in the housing 200. At this time, an electrolytic solution is injected into the housing 200, and at least the anode 10 and the cathode 20 are impregnated with the electrolytic solution. The housing 200 may be made of, for example, a metal material such as aluminum (Al) and / or a plastic material. In addition, according to an exemplary embodiment of the present invention, a finishing plate (not shown) may be installed on the upper portion of the housing 200, and then closed by a curling process in which the upper end is bent.

The anode 10 and the cathode 20 include metal collectors 12 and 22 and activated carbon electrodes 14 and 24 formed on the metal collectors 12 and 22. The activated carbon electrodes 14 and 24 are formed on at least one surface of the metal collectors 12 and 22. Specifically, the activated carbon electrodes 14 and 24 may be formed on only one side of the metal collectors 12 and 22, or on both sides of the metal collectors 12 and 22. Hereinafter, an exemplary embodiment of each component constituting the electric double layer capacitor (EDLC) according to the present invention will be described.

[1] metal collectors

The metal collectors 12 and 22 are selected from a metal foil. The metal current collectors 12 and 22 are made of a metal thin film selected from aluminum (Al), copper (Cu), titanium (Ti), nickel (Ni), stainless steel (SUS) Lt; / RTI > At this time, it is preferable that the metal current collectors 12 and 22 are selected from a metal etching foil whose surface is etched for a high surface area. In one example, the metal current collectors 12 and 22 may advantageously use an aluminum (Al) etched foil.

The metal collectors 12 and 22 may have a thickness T of, for example, 15 占 퐉 or less. The metal current collectors 12 and 22 may have a thickness T of 2 to 15 占 퐉, for example. At this time, when the thickness T of the metal current collectors 12 and 22 is less than 2 mu m, the high voltage characteristics and the like may be lowered if it is too thin, and the flexible characteristics and the like may be lowered if it is too thick . In consideration of this point, it is preferable that the metal current collectors 12 and 22 have a thickness T of 5 mu m to 12 mu m.

According to the embodiment of the present invention, at least one of the metal collectors 12 and 22 among the metal collectors 12 and 22 constituting the positive electrode 10 and the negative electrode 20 is a metal oxide film Layer 12a (22a). 2, the metal collectors 12 and 22 have a structure in which metal oxide layers 12a and 22a are formed on the surfaces of the metal collectors 12 and 22, which are joined to the activated carbon electrodes 14 and 24, respectively. At this time, it is preferable that both the metal collectors 12 and 22 constituting the anode 10 and the cathode 20 include the metal oxide film layers 12a and 22a.

The metal oxide film layers 12a and 22a are formed by surface oxidation of the metal collectors 12 and 22 and have porosity. Further, as shown in Fig. 2, the metal oxide film layer 12a (22a) may have a concavo-convex structure (a). At this time, the concavo-convex structure (a) has, for example, random and irregular roughness. According to the present invention, the contact area between at least the activated carbon electrodes 14 and 24 and the metal collectors 12 and 22 is widened by the metal oxide film layers 12a and 22a to have a high capacity. The interlayer coupling force between the activated carbon electrodes 14 and 24 and the metal collectors 12 and 22 is improved.

The metal oxide film layers 12a and 22a may have a thickness (Ta) of, for example, 0.1 탆 to 10 탆. At this time, when the thickness Ta of the metal oxide film layer 12a (22a) is less than 0.1 占 퐉, the effect of improving the contact area (capacity improvement) due to its formation may be insignificant. When the thickness (Ta) of the metal oxide film layer 12a (22a) exceeds 10 占 퐉, for example, the resistance characteristic and the like may not be preferable. Considering this point, it is preferable that the metal oxide film layer 12a (22a) has a thickness (Ta) of 0.5 占 퐉 to 8 占 퐉, or 1 占 퐉 to 5 占 퐉.

According to a preferred embodiment of the present invention, the metal current collectors 12 and 22 have a thickness T of 5 占 퐉 to 12 占 퐉, and the metal oxide film layers 12a and 22a formed thereon have a thickness of 1 占 퐉 (Capacity improvement), resistance characteristics, and / or high-voltage characteristics (operation voltage) of the contact area with the activated carbon electrodes 14 and 24 are preferable.

The metal oxide film layers 12a and 22a are formed through an oxidation reaction using electrolysis. At this time, in the electrolytic oxidation, the metal collectors 12 and 22 are made positive (+). As the negative electrode (-) for electrolytic oxidation, for example, a carbon material such as a graphite plate (or a black rope) can be used. In electrolytic oxidation, an aqueous acid solution is used as the electrolytic aqueous solution.

An acid aqueous solution is injected into the electrolytic bath according to one embodiment and then the metal current collectors 12 and 22 and the graphite plate are immersed in an aqueous acid solution, (12) and (22). Then, a graphite plate is connected to the negative electrode (-), and then a voltage is applied. When the voltage is applied in this way, the oxidation proceeds to grow porous metal oxide film layers 12a and 22a on the surfaces of the metal collectors 12 and 22, and the surface of the metal oxide film layers 12a and 22a Has a concavo-convex structure (a).

In addition, the thickness Ta of the metal oxide layer 12a 22a can be controlled by adjusting the applied voltage, the application time of the voltage, and / or the temperature of the electrolytic aqueous solution during the electrolytic oxidation. For example, the oxidation can be performed at a voltage of 5 V to 15 V for 30 seconds (sec) to 30 minutes (min). And the electrolytic aqueous solution can be maintained at a temperature of from 10 캜 to 50 캜. When the oxidation proceeds under these conditions, the metal oxide film layers 12a and 22a having the above-described thickness Ta can be formed. Although not particularly limited, a current of about 0.2 A to 5 A may be applied during the electrolytic oxidation.

In addition, according to a preferred embodiment, ultrasonic vibration may be applied to the electrolytic aqueous solution using the ultrasonic generator during the electrolytic oxidation. When oxidation proceeds while applying ultrasonic vibration as described above, the porosity, the concavo-convex structure (a) and / or growth rate of the metal oxide film layers 12a and 22a can be improved.

The electrolytic aqueous solution is an aqueous solution containing at least one acid selected from perchloric acid (HClO 4 ), sulfuric acid (H 2 SO 4 ), hydrochloric acid (HCl), nitric acid (HNO 3 ) and phosphoric acid (H 3 PO 4 ) Can be used. At this time, according to a preferred embodiment, it is preferable that the electrolytic aqueous solution further contains oxalic acid (C 2 H 2 O 4 ). Specifically, the electrolytic solution comprises a first acid and a second acid, said first acid is perchloric acid (HClO 4), sulfuric acid (H 2 SO 4), hydrochloric acid (HCl), nitric acid (HNO 3) and phosphoric acid (H 3 PO 4 ), and the like, and the second acid is selected from oxalic acid (C 2 H 2 O 4 ), and the electrolytic aqueous solution preferably further comprises oxalic acid (C 2 H 2 O 4 ). As described above, when oxalic acid (C 2 H 2 O 4 ) is further contained in the electrolytic aqueous solution, the chemical resistance and / or hardness of the metal oxide film layers 12a and 22a are improved.

Specifically, in the case of using an electrolytic aqueous solution containing oxalic acid (C 2 H 2 O 4 ) as a second acid rather than the electrolytic aqueous solution containing the first disturbance listed above, the metal oxide film layer 12a (22a The chemical resistance and / or the hardness and the like are improved. The metal oxide film layers 12a and 22a may be dissolved by an electrolyte (particularly an organic solvent) of an electric double layer capacitor (EDLC). An electrolytic aqueous solution containing oxalic acid (C 2 H 2 O 4 ) It is possible to improve the chemical resistance and / or hardness of the metal oxide film layers 12a and 22a and to prevent dissolution by the electrolytic solution. Thus, for example, gas generation during charging / discharging is small and electrical characteristics can be improved. In addition, when perchloric acid (HClO 4 ) is used as the first acid, it is advantageous in terms of the porosity, the concavo-convex structure (a) and / or the growth rate of the metal oxide film layers 12a and 22a.

According to one embodiment, the electrolytic aqueous solution contains 5 to 15% by weight of the first acid, 0.5 to 3% by weight of the second acid (oxalic acid) and the remaining amount of water (distilled water, etc.) based on the total weight of the electrolytic aqueous solution can do. In addition, the electrolytic aqueous solution may further include a conductive salt which flows electricity more efficiently, and the conductive salt may be contained in an amount of, for example, 2 to 15% by weight based on the total weight of the electrolytic aqueous solution.

The conductive salt is not particularly limited, and may be selected from, for example, sodium borate (NaBO 2 ) and / or sodium chloride (NaCl). In one example, the electrolytic aqueous solution comprises 5 to 15 wt% of perchloric acid (HClO 4 ), 0.5 to 3 wt% of oxalic acid (C 2 H 2 O 4 ), 2 to 15 wt% of sodium borate (NaBO 2 ) (Such as distilled water).

[2] activated carbon electrode

The activated carbon electrodes 14 and 24 preferably include activated carbon, a binder, and a conductive material. The activated carbon electrodes 14 and 24 are formed on the metal oxide film layers 12a and 22a of the metal collectors 12 and 22 as described above. More specifically, at least one activated carbon electrode 14 ((a) is formed on the metal oxide film layer 12a (22a) of the metal current collectors 12 and 22 by using an activated carbon electrode composition including activated carbon, a binder and a conductive material. 24 are formed.

At this time, the activated carbon electrodes 14 and 24 may be produced by forming an activated carbon electrode composition including, for example, activated carbon, a binder and a conductive material on a sheet, Or by rolling and rolling the activated carbon electrode composition on the metal oxide film layers 12a and 22a of the metal collectors 12 and 22, Dried, and then rolled and rolled. 2 shows an activated carbon electrode composition coated and dried on the metal oxide layers 12a and 22a of the metal collectors 12 and 22 and rolled through a roller R.

In forming the activated carbon electrodes 14 and 24, a temperature in the same range as usual may be applied during rolling. During rolling, a temperature of, for example, 120 ° C to 180 ° C may be applied. That is, referring to FIG. 2, when the rolling is performed using the roller R, the temperature of the roller R may be maintained at 120 ° C. to 180 ° C. to perform rolling.

According to a preferred embodiment of the present invention, the rolling may be carried out at room temperature without applying a separate temperature. That is, in FIG. 2, the temperature of the roller R can be rolled to room temperature. In this case, since no extra temperature is applied to the roller R, it is advantageous in terms of energy saving, and in particular, the increase in resistance of the activated carbon electrodes 14 and 24 can be prevented.

Concretely, when rolling is performed at a high temperature (for example, 120 to 180 ° C) during rolling, the volume of the binder is widened (volume expansion of the binder) and the resistance of the activated carbon electrodes 14 and 24 Can be increased. However, according to a preferred embodiment of the present invention, when the rolling is performed at room temperature, the bulge of the binder does not occur and the increase in resistance can be prevented.

In the present invention, room temperature refers to a temperature at which no artificial heat (temperature) is applied, which may vary depending on the season. In the present invention, the ambient temperature may be in the range of, for example, 2 ° C to 35 ° C, more specifically 5 ° C to 30 ° C, or 5 ° C to 25 ° C.

(1) activated carbon

The activated carbon is not particularly limited. As the activated carbon, for example, powdery activated carbon commonly used in the art can be used. The activated carbon may be selected from, for example, those having a specific surface area of at least 800 m 2 / g or more and an average particle size of 2 μm to 50 μm. The larger the specific surface area of the activated carbon, the more advantageous it is in the electrical characteristics. For this, the activated carbon may be selected from those having a specific surface area of 1500 m < 2 > / g or more, preferably from 1800 m < 2 > However, if the specific surface area of activated carbon is too large, the electrode density may be lowered. Considering this point, the activated carbon preferably has a specific surface area of 1500 to 2500 m 2 / g, more preferably a specific surface area of 1800 to 2200 m 2 / g.

In addition, the average particle size of the activated carbon may affect energy storage and resistance characteristics and the like. When the average particle size of the activated carbon is less than 2 mu m, for example, energy storage characteristics and the like may be lowered. If the average particle size of the activated carbon is more than 50 mu m, for example, the resistance characteristic may be deteriorated. In view of this point, the activated carbon may be selected from those having an average particle size distribution of 5 mu m to 30 mu m.

In the present invention, the activated carbon may be carbonized and activated from a carbon raw material (activated carbon precursor) to have a porous structure, and the raw material and the activation method are not particularly limited. The activated carbon may be, for example, a resin such as phenol resin; Plant systems such as palm shells (coconut shells), apricot seeds and rice hulls; And coal / petroleum based materials such as pitch cokes and the like as raw materials and carbonizing and activating them.

The activated carbon may be activated by using an alkali activating agent such as potassium hydroxide (KOH) and / or activated by steam, but it is preferably activated by steam (water vapor) It is better to use activated carbon. At this time, activated carbon activated by steam (water vapor) is less in impurities and less in gas generation than activated carbon activated by an alkali activator (such as KOH), and is favorable for the present invention because it is advantageous in electrical characteristics.

According to one embodiment, the activated carbon may be a palm shell activated carbon activated by steam of a coconut shell carbide. As commercialized products, for example, YP series products (for example, YP-50F and YP-80F) can be used.

(2) Binders

The binder may be an adhesive, and may be selected from those conventionally used in the art, for example. The binder may be selected from the group consisting of polytetrafluoroethylene (PTFE), carboxymethylcellulose (CMC), polyvinylpyrrolidone (PVP), polyvinylidene fluoride (PVDF), acrylic acid, acrylic rubber, nitrile-butadiene rubber Butadiene rubber (NBR), styrene-butadiene rubber (SBR), butyl rubber (BR), and polyvinyl alcohol (PVA).

The binder may be used in an amount of 0.5 to 20 parts by weight (based on the solid content) based on 100 parts by weight of the activated carbon. When the content of the binder is less than 0.5 part by weight, the adhesion of the binder is insignificant. When the amount of the binder is more than 20 parts by weight, the synergistic effect of excessive use is not so large, which may be undesirable for electrical properties. Considering this point, the binder may be used in an amount of 1 to 15 parts by weight (based on the solid content) based on 100 parts by weight of the activated carbon.

According to a preferred embodiment of the present invention, the binder includes a butadiene-styrene-alkyl methacrylate copolymer. According to a specific embodiment, the binder comprises a mixture of one or more binders selected from the listed binders (first binder) and the butadiene-styrene-alkyl methacrylate copolymer (second binder), or the butadiene-styrene -Alkyl methacrylate copolymer (second binder) alone.

The butadiene-styrene-alkyl methacrylate copolymer (second binder) is a ternary copolymer of butadiene, styrene, and alkyl methacrylate. The butadiene-styrene-alkyl methacrylate copolymer includes 30 to 45% by weight of butadiene- 10% by weight and an alkyl methacrylate monomer in an amount of 40 to 60% by weight. At this time, the alkyl methacrylate monomer may be selected from, for example, methyl methacrylate, ethyl methacrylate and / or n-butyl methacrylate.

Specific examples of the butadiene-styrene-alkyl methacrylate copolymer (second binder) include butadiene-styrene-methyl methacrylate copolymer, butadiene-styrene-ethyl methacrylate copolymer and / or butadiene- Butyl methacrylate copolymer, and the like.

According to the present invention, the butadiene-styrene-alkyl methacrylate copolymer (second binder) can improve the binding force between the activated carbon particles and the conductive material particles as compared with the conventional binders (first binder) , The interlayer adhesion between the activated carbon electrodes 14 and 24 and the metal collectors 12 and 22 and the electrode density of the activated carbon electrodes 14 and 24 are effectively reduced. For this reason, electrical characteristics such as capacitance and resistance can be improved.

According to a preferred form, the binder may comprise at least carboxymethylcellulose (first binder) and butadiene-styrene-alkyl methacrylate copolymer (second binder). At this time, carboxymethylcellulose (first binder) effectively improves the dispersibility of the butadiene-styrene-alkyl methacrylate copolymer (second binder) together with the function of the binder. Accordingly, according to the present invention, when carboxymethylcellulose (first binder) and butadiene-styrene-alkyl methacrylate copolymer (second binder) are mixed and used as a binder, interlayer adhesion, gas generation and / Characteristics and the like.

According to a preferred embodiment of the present invention, the binder may be used in a weight ratio of 1: 0.2 to 5: carboxymethylcellulose (first binder) and butadiene-styrene-alkyl methacrylate copolymer (second binder) . At this time, when the amount of the butadiene-styrene-alkyl methacrylate copolymer (second binder) used is less than 0.2 weight ratio with respect to carboxymethyl cellulose (first binder), a butadiene-styrene-alkyl methacrylate copolymer (Such as interlayer adhesion and electrical characteristics) may be insignificant. When the amount of the butadiene-styrene-alkyl methacrylate copolymer (second binder) is more than 5 parts by weight, the content of carboxymethyl cellulose (first binder) becomes relatively low and, for example, a butadiene-styrene- The dispersibility and the like of the acrylate copolymer (second binder) may be lowered.

The butadiene-styrene-alkyl methacrylate copolymer (second binder) may be selected from nano-particles having an average particle size of 50 nm to 400 nm, more preferably an average particle size of 80 nm to 230 nm Nanoparticles. ≪ / RTI > When the butadiene-styrene-alkyl methacrylate copolymer (second binder) has a nano-size, it is uniformly dispersed among the activated carbon particles to improve the adhesive strength and electrical characteristics more effectively. At this time, according to one embodiment, the binder may be added to a solution (for example, an aqueous solution) containing carboxymethylcellulose (first binder), the nano-sized butadiene-styrene-alkyl methacrylate copolymer ) Can be used.

(3) Conductive material

The conductive material is not particularly limited as long as it has electrical conductivity and can be selected from those conventionally used in the art, for example. The conductive material may include, for example, carbon black such as acetylene black, graphite, graphene, carbon nanotube (CNT), and carbon nanofiber (CNF); And / or an oxide powder such as titanium oxide and ruthenium oxide, and the like.

In addition, the conductive material may have an average particle size of, for example, 40 탆 or less, more specifically, an average particle size of 3 탆 to 20 탆. The conductive material may be used in an amount of 0.2 to 20 parts by weight based on 100 parts by weight of activated carbon. At this time, when the content of the conductive material is less than 0.2 parts by weight, the improvement of the electric conductivity (that is, the improvement of the internal resistance characteristic) is small with use thereof, and when it exceeds 20 parts by weight, the capacitance may be decreased. Considering this point, the conductive material may be used in an amount of 2 to 10 parts by weight based on 100 parts by weight of activated carbon.

(4) Solvent

Meanwhile, the activated carbon electrode composition may further include a solvent. When the activated carbon electrodes 14 and 24 are formed by coating on the metal collectors 12 and 22 in manufacturing the activated carbon electrodes 14 and 24, May be included as a diluent for acid and coating properties.

The solvent is not particularly limited as long as it is volatilized by heat or can be volatilized by natural drying, for example, water and / or an organic solvent. Examples of the organic solvent include methyl pyrrolidone (NMP) and the like. The solvent may be mixed with, for example, 5 to 500 parts by weight based on 100 parts by weight of activated carbon.

[3] separator

The separator 30 is an insulating porous member, for example, which is commonly used in the art can be used.

The separator 30 may be selected from, for example, a nonwoven fabric (or a woven fabric) or a glass fiber nonwoven fabric selected from polyethylene (PE) based, polypropylene (PP) based and / or cellulose based, It is not.

[4] electrolyte

The electrolytic solution may be selected from an organic electrolyte solution, for example, for high-voltage characteristics and the like. The electrolytic solution includes an electrolyte (electrolytic salt) and an organic solvent. At this time, the types of the electrolyte and the organic solvent are not particularly limited, and those conventionally used in the art can be used.

Examples of the electrolyte include quaternary ammonium salts such as tetraethylammonium and triethylmethylammonium; (C 2 H 5 ) 4 NBF 4 ; Aliphatic cyclic ammonium salts such as N-ethyl-N-methylpyrrolidinium and N, N-tetramethylenepyrrolidinium; Quaternary imidazole such as 1,3-dimethylimidazole and 1-ethyl-3-methylimidazole; And / or derivatives thereof, and the like. In addition, the electrolyte may be contained (dissolved) in the electrolyte solution, for example, at 0.1 to 4.0 mol / L, preferably 0.5 to 3.0 mol / L. At this time, if the concentration of the electrolyte is high, the resistance of the electrolyte may become large or the discharge characteristic may be deteriorated. If the concentration of the electrolyte is low, the solubility may be deteriorated or crystal precipitation may be caused.

The organic solvent is not particularly limited as long as it can dissolve (dilute) the electrolyte. Examples of the organic solvent include organic solvents such as propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, -butylolactone, dimethylsulfoxide, sulfolane, dimethylformamide, dimethylacetamide, Selected from triesters, maleic anhydride, succinic anhydride, phthalic anhydride, 1,3-propane sultone, nitrobenzene, 1,2-dimethoxyethane, tetrahydrofuran, acetonitrile, nitromethane and / .

Further, according to an exemplary embodiment, the electrolytic solution may further include a gas generation inhibitor. In general, the electric double layer capacitor (EDLC) has an internal pressure (internal pressure) increased over time. The rise of the breakdown voltage provides the cause of the low operating voltage. That is, if the internal pressure is increased, the electrolyte may be leaked or the electric double layer capacitor (EDLC) cell may be broken. Accordingly, in order to prevent accumulation of pressure (increase in internal pressure), it is necessary to operate at a low voltage, so that the increase of the internal pressure causes the operating voltage to be lowered.

In the present invention, the gas generation inhibitor solves the problem of the rise in the internal pressure as described above, and has a high operating voltage (high voltage). At the same time, the gas generation inhibitor promotes the long life of the electric double layer capacitor (EDLC).

Generally, gas is generated inside an electric double layer capacitor (EDLC) cell. The generation of the gas can be caused by, for example, decomposition reaction of the electrolyte or chemical reaction occurring at the contact interface of the activated carbon electrodes 14 and 24 and the electrolyte. At this time, most of the generated gas may include an acid component. The gas thus generated causes rise of the internal pressure and deterioration, thereby lowering the operating voltage and lifetime characteristics.

In the present invention, the gas generation inhibitor is not particularly limited as long as it can suppress the gas generation as described above. It is sufficient that the gas generation inhibitor is capable of suppressing (eliminating) the generation of gas by, for example, adsorbing or neutralizing the gas generated in the electrolyte solution.

The gas generation inhibitor may be liquid and / or solid and may be dissolved and / or dispersed in the electrolyte solution. According to one embodiment, the gas generation inhibitor may include at least one selected from a basic organic compound and a porous inorganic particle. At this time, the basic organic compound can be inhibited (removed) by, for example, dissolving in an electrolytic solution and generating a gas through a neutralization reaction with the generated gas (acid component). Further, the porous inorganic particles can be dispersed in, for example, an electrolyte solution, and the generation of gas can be suppressed (eliminated) by adsorbing the generated gas.

Therefore, according to the embodiment of the present invention, when the gas generation inhibitor is included in the electrolytic solution, generation of gas which causes increase in internal pressure and deterioration can be suppressed (eliminated), and high operating voltage (high voltage) and long life can be obtained.

The basic organic compound may be selected from, for example, an alkaloid compound having at least one nitrogen (N) in the molecule, and specific examples thereof include 1,3-diazole, pyridine, triethylamine, and the like may be used.

The porous inorganic particles may be selected from, for example, silicon (Si), aluminum (Al), magnesium (Mg), sodium (Na), potassium (K), titanium May be selected from porous inorganic oxide particles having one or more elements, and specific examples thereof may be selected from silica, alumina, titania and zeolite. In addition, the porous inorganic particles may have an average particle size of, for example, 0.1 탆 to 20 탆. In addition, according to one embodiment, the gas generation inhibitor may be included in the electrolytic solution in an amount of 0.001 wt% to 10 wt%, but is not limited thereto.

According to the present invention described above, an improved super-high capacity capacitor and a manufacturing method thereof are provided. According to the present invention, the contact area between, for example, the activated carbon electrodes 14 and 24 and the metal collectors 12 and 22 is improved by the metal oxide film layers 12a and 22a to have excellent electrical characteristics .

Further, according to the present invention, it has excellent electrical characteristics and long-term reliability. Specifically, according to the present invention, a high capacity retention and a low resistance increase according to the elapse of time (or the number of charge / discharge cycles) can be achieved, and excellent long-term reliability can be achieved. According to the present invention, according to the exemplary embodiment, when the gas generation inhibitor is included in the electrolytic solution, for example, the operating voltage (high voltage characteristic) and the life characteristic are further improved.

Hereinafter, examples and comparative examples of the present invention will be exemplified. The following examples are provided to illustrate the present invention only and the technical scope of the present invention is not limited thereto. In addition, the following comparative example is not meant to be a prior art, but is provided for comparison with embodiments only.

[Examples 1 to 3]

(1) Oxidation treatment of Al etched foil

An Al (aluminum) etched foil having a thickness of about 10 mu m was prepared. The prepared Al etched foil was washed with water and dried. Then, the Al etching foil and the graphite plate were immersed in an electrolytic bath, and an Al etching foil was connected to the positive electrode (+) and a graphite plate was connected to the negative electrode (-). At this time, an electrolytic aqueous solution containing 10% by weight of perchloric acid (HClO 4 ), 2 % by weight of oxalic acid (C 2 H 2 O 4 ), 8% by weight of sodium borate (NaBO 2 ) and distilled water was injected into the electrolytic bath.

Next, while maintaining the temperature of the electrolytic aqueous solution at about 25 캜 and applying ultrasonic vibration through the ultrasonic generator to the electrolytic aqueous solution, a voltage of about 12 V and a current of about 0.8 A were applied for about 15 minutes to oxidize the Al etch foil A porous Al oxide film layer having a thickness of about 2.6 mu m was formed. At this time, the thickness of the Al oxide film layer was measured by a cross-sectional photograph using a scanning electron microscope.

(2) Electrode Fabrication

First, an aqueous solution containing 28% by weight (based on solids) of carboxymethyl cellulose (CMC) was prepared and then a butadiene-styrene-methyl methacrylate copolymer (BSM) was added thereto. The mixture was stirred at 5,000 rpm for 15 minutes Respectively. The butadiene-styrene-methyl methacrylate copolymer (BSM) was prepared by copolymerizing 34% by weight of a butadiene monomer, 8% by weight of a styrene monomer and 58% by weight of a methyl methacrylate monomer and had a particle size distribution of about 120 nm to 220 nm Nanoparticles were used.

Next, activated carbon and acetylene black were put into the stirring solution, and then mixed and stirred at about 1,800 rpm (at 30 kPa) for 10 minutes to prepare an activated carbon electrode composition on a slurry. At this time, YP-50F product (average particle size about 8 μm) was used as the activated carbon activated coconut shell activated carbon, and Super P product (average particle size about 4.5 μm) was used for the acetylene black. The activated carbon electrode composition used about 6 parts by weight of acetylene black and about 1.5 parts by weight of carboxymethyl cellulose (CMC) based on 100 parts by weight of activated carbon. 2 parts by weight (Example 1), 3 parts by weight (Example 2) and 4 parts by weight (based on 100 parts by weight of activated carbon) of the butadiene-styrene-methyl methacrylate copolymer (BSM) Example 3).

An activated carbon electrode composition (slurry) according to each of Examples 1 to 3 was coated on the Al oxide film layer of the Al etching foil by a doctor blade method and then dried. Thereafter, rolled and rolled at about 150 캜 to form an activated carbon electrode having a thickness of about 120 탆 on the Al oxide film layer to produce an electrode sheet having a laminated structure of Al etching foil / Al oxide film / activated carbon electrode.

(3) Production of EDLC cell

A cylindrical EDLC cell was prepared by the ordinary process using the electrode sheet prepared above. Specifically, the prepared electrode sheet was cut into a predetermined size (20 mm.times.15 cm), a connection terminal was provided, and a separator (PE nonwoven fabric) was interposed between the two electrode sheets. Thereafter, it was wound in a cylindrical shape, taped and finished, and then housed in a cylindrical aluminum case. Then, the electrolyte solution was injected into the case, and then the upper end of the case was sealed.

The electrolytic solution was a solution [(C 2 H 5 ) 4 NBF 4 / ACN] in which 1.0 mol / L of (C 2 H 5 ) 4 NBF 4 (electrolyte) and acetonitrile (organic solvent) were mixed.

[Example 4]

An EDLC cell was prepared in the same manner as in Example 1, except that a product activated with KOH was used as the activated carbon in contrast to Example 1. [ Specifically, phenol resin-based activated carbon (product MSP-20) activated with KOH was used as activated carbon in this embodiment.

[Example 5]

An EDLC cell was prepared in the same manner as in Example 1, except that styrene-butadiene rubber (SBR) was used instead of butadiene-styrene-methyl methacrylate copolymer (BSM) . Specifically, in this example, styrene-butadiene rubber (SBR) generally used in the production of EDLC was used instead of butadiene-styrene-methyl methacrylate copolymer (BSM) as a binder, , An activated carbon electrode was formed using an activated carbon electrode composition comprising about 6 parts by weight of acetylene black, about 1.5 parts by weight of carboxymethyl cellulose (CMC), and about 2 parts by weight of styrene-butadiene rubber (SBR).

[Example 6]

In contrast to Example 1, an EDLC cell was prepared in the same manner as in Example 1, except that the composition of the electrolytic aqueous solution was changed when the Al etched foil was oxidized. Specifically, in this embodiment, in forming the Al oxide film layer on the surface of the Al etching foil, an aqueous solution containing 12% by weight of perchloric acid (HClO 4 ), 8% by weight of sodium borate (NaBO 2 ) Was used to form a porous Al oxide film layer having a thickness of about 2.6 mu m.

[Examples 7 and 8]

An EDLC cell was fabricated in the same manner as in Example 1, except that the thickness of the Al oxide film layer was different from that of the first embodiment. Specifically, in this embodiment, in forming the Al oxide film layer on the surface of the Al etch foil, the thickness of the Al oxide film is about 0.8 mu m (Example 7) and about 6.2 mu m Mu m (Example 8).

At this time, in the case of forming the Al oxide film layer, 10 wt% of sulfuric acid (H 2 SO 4 ), 2 wt% of oxalic acid (C 2 H 2 O 4 ), 8 wt% of sodium borate (NaBO 2 ) An electrolytic aqueous solution consisting of distilled water was used and oxidized for about 2 minutes by applying a voltage of about 10V. In the case of Example 8, an electrolytic aqueous solution containing 10 wt% of perchloric acid (HClO 4 ), 2 wt% of oxalic acid (C 2 H 2 O 4 ), 8 wt% of sodium borate (NaBO 2 ) A voltage of about 15 V was applied, and oxidation proceeded for about 25 minutes.

[Comparative Example 1]

An EDLC cell was fabricated in the same manner as in Example 1, except that the Al etch foil and the binder were different from those of Example 1. Specifically, in this comparative example, an Al etch foil which was not oxidized was used. As a binder, instead of butadiene-styrene-methyl methacrylate copolymer (BSM), styrene-butadiene rubber (SBR) generally used in the production of EDLC was used instead of acetylene black An activated carbon electrode was formed using an activated carbon electrode composition comprising about 6 parts by weight of a carbon black, about 1.5 parts by weight of carboxymethyl cellulose (CMC), and about 2 parts by weight of styrene-butadiene rubber (SBR).

≪ Evaluation of electrical characteristics &

The capacitance (F / cc) and the internal resistance (m?) Per unit volume at a voltage of 2.7 V were measured for the EDLC cell according to each of the Examples and Comparative Examples, and the results are shown in Table 1 below .

             <Electrical Characteristic Evaluation Results of EDLC Cell (@ 2.7V)>
Remarks Al oxide film layer
Activated carbon electrode
capacitance
[F / cc]
resistance
[mΩ] thickness
Electrolytic aqueous solution Activated carbon Binder (content) Example 1
2.6 탆 HClO 4 + C 2 H 2 O 4 YP-50F CMC + BSM (2 parts by weight) 13.0 7.5 Example 2
2.6 탆 HClO 4 + C 2 H 2 O 4 YP-50F CMC + BSM (3 parts by weight) 12.8 8.3 Example 3
2.6 탆 HClO 4 + C 2 H 2 O 4 YP-50F CMC + BSM (4 parts by weight) 12.6 8.4 Example 4
2.6 탆 HClO 4 + C 2 H 2 O 4 MSP-20 CMC + BSM (2 parts by weight) 15.6 11.3 Example 5
2.6 탆 HClO 4 + C 2 H 2 O 4 YP-50F CMC + SBR (2 parts by weight) 12.7 8.4 Example 6
2.6 탆 HClO 4 YP-50F CMC + BSM (2 parts by weight) 12.2 9.0 Example 7
0.8 탆 H 2 SO 4 + C 2 H 2 O 4 YP-50F CMC + BSM (2 parts by weight) 12.2 8.8 Example 8
6.2 탆 HClO 4 + C 2 H 2 O 4 YP-50F CMC + BSM (2 parts by weight) 13.1 9.6 Comparative Example 1
- - YP-50F CMC + SBR (2 parts by weight) 11.5 10.0
* YP-50F: Coconut shell activated carbon (activated by steam)
* MSP-20: Phenolic resin-based activated carbon (activated by KOH)
* CMC: Carboxymethylcellulose
* BSM: Butadiene-styrene-methyl methacrylate copolymer
* SBR: styrene-butadiene rubber

As shown in Table 1, the cell specimen in which the Al oxide film layer is formed on the Al etched foil has higher capacity than the cell specimen in Comparative Example 1.

Also, in comparison with Examples 1, 7, and 8, it can be seen that as the thickness of the Al oxide film increases, the capacity increases. However, as in Embodiment 8, it can be seen that the resistance becomes somewhat higher if the thickness is too thick.

In contrast to Examples 1 and 6, in the case of using oxalic acid (C 2 H 2 O 4 ) as an electrolytic aqueous solution in forming the Al oxide film layer (Example 1), the capacity and resistance characteristics . &Lt; / RTI &gt; It is considered that this is because the use of further oxalic acid (C 2 H 2 O 4 ) improves the chemical resistance and hardness of the Al oxide film layer and prevents the dissolution of the Al oxide film layer by the electrolytic solution.

On the other hand, in the case of Examples 1 and 4, in the case of using activated carbon, the product activated with steam (YP-50F) (Example 1) The advantage can be seen. This is because the activated carbon (YP-50F) activated by steam is lower in content of impurities than activated carbon activated by KOH (MSP-20).

In contrast to Examples 1 and 5, when a nano-sized butadiene-styrene-methyl methacrylate copolymer (BSM) was used as the binder (Example 1), styrene-butadiene rubber (SBR) (Example 5) is more advantageous in terms of capacity and resistance characteristics. This is because it has a high dispersibility and an improvement in adhesion and a low gas generation.

&Lt; Evaluation of adhesion &

In order to evaluate the interlaminar adhesive strength depending on the content and type of the binder, the interlaminar adhesive strength of the electrode sheet (Al-etched foil + laminated sheet of activated carbon electrode) according to Examples 1 to 3, Example 5 and Comparative Example 1 was evaluated. At this time, a 90 degree peel test method was used for the interlayer adhesion, and the peeling force between the Al etched foil and the activated carbon electrode was evaluated. The results are shown in Fig.

As shown in FIG. 3, it can be seen that as the content of the binder, that is, the content of the butadiene-styrene-methyl methacrylate copolymer (BSM) increases, the interlayer adhesion is excellent.

In contrast to Example 1, Example 5 and Comparative Example 1, when a butadiene-styrene-methyl methacrylate copolymer (BSM) was used in the same amount (2 parts by weight) (Example 1) It can be seen that the interlaminar adhesive strength is superior to the case of using butadiene rubber (SBR) (Example 5 and Comparative Example 1).

<Long term reliability evaluation>

Capacitance Retention (%) and Resistance Increase (%) were evaluated for EDLC cells according to Examples 1 and 5 and Comparative Example 1. The results are shown in FIGS. 4 to 6 attached hereto.

FIG. 4 shows a capacity retention rate (%) according to a discharge rate ([C]), and FIG. 5 shows a capacity retention rate (%) according to a charge / discharge cycle number (cycle number). At this time, charge / discharge conditions are Charge: CC (1.0C) -CV (4.2V) and Discharge: CC (1.0C) to 2.7V. 6 shows the resistance increase rate (%) over time versus initial resistance. 6, the x-axis is time (hrs).

As shown in FIGS. 4 to 6, the cells according to Examples 1 and 5 have higher capacity retention ratios and lower resistance increase rates than the cells according to Comparative Example 1, while maintaining high capacity and low resistance. This means excellent long-term reliability.

In contrast to Examples 1 and 5, when a nano-sized butadiene-styrene-methyl methacrylate copolymer (BSM) was used as the binder (Example 1), styrene-butadiene rubber (SBR) (Example 5) is superior in terms of long-term reliability, and in particular, the cycle life is improved as shown in FIG.

[Examples 9 to 17]

The properties of the binder according to the type and content of the binder were measured in the same manner as in Example 1 except that the type and content of the binder were varied according to each of Examples (9 to 17) . The EDLC cell according to each example was evaluated for capacitance and resistance, and the results are shown in Table 2 below. At this time, in the following [Table 2], the content (parts by weight) of the binder is based on the solid basis with respect to 100 parts by weight of activated carbon.

Specifically, in Examples 9 to 11, a mixture of carboxymethylcellulose (CMC) and butadiene-styrene-butyl methacrylate copolymer (BSB) was used as a binder, and the butadiene-styrene-butyl methacrylate copolymer (BSB) was prepared by copolymerizing 40% by weight of a butadiene monomer, 5% by weight of a styrene monomer and 55% by weight of a butyl methacrylate monomer, and fine particles having a particle size distribution of about 80 nm to 120 nm were used.

In Examples 12 to 14, a mixture of carboxymethylcellulose (CMC) and styrene-butadiene rubber (SBR) was used as a binder. In Examples 15 to 17, carboxymethylcellulose (CMC) A mixture of tetrafluoroethylene (PTFE) was used.

[Example 18]

In contrast to Example 9, an EDLC cell was manufactured by performing the same operation except that the rolling temperature of the activated carbon electrode was changed during rolling. Specifically, in Example 18, the same operation as in Example 9 was carried out, except that the activated carbon electrode was rolled at room temperature (about 12 ° C).

            <Electrical Characteristic Evaluation Results of EDLC Cell (@ 2.7V)> Remarks Binder (content) Rolling temperature capacitance
[F / cc] resistance
[mΩ] Example 9
CMC (1.0 part by weight) + BSB (0.5 part by weight) 150 ℃ 12.6 8.5 Example 10
CMC (1.0 part by weight) + BSB (0.75 part by weight) 150 ℃ 12.6 8.2 Example 11
CMC (1.0 part by weight) + BSB (1.0 part by weight) 150 ℃ 12.7 7.8 Example 12
CMC (1.0 part by weight) + SBR (0.5 part by weight) 150 ℃ 12.5 9.1 Example 13
CMC (1.0 part by weight) + SBR (0.75 part by weight) 150 ℃ 12.4 8.9 Example 14
CMC (1.0 part by weight) + SBR (1.0 part by weight) 150 ℃ 12.6 8.5 Example 15
CMC (1.0 part by weight) + PTFE (0.5 part by weight) 150 ℃ 12.4 10.2 Example 16
CMC (1.0 part by weight) + PTFE (0.75 part by weight) 150 ℃ 12.4 9.6 Example 17
CMC (1.0 part by weight) + PTFE (1.0 part by weight) 150 ℃ 12.5 9.2 Example 18
CMC (1.0 part by weight) + BSB (0.5 part by weight) Room temperature 12.8 8.1
* CMC: Carboxymethylcellulose
* BSB: Butadiene-styrene-butyl methacrylate copolymer
* SBR: styrene-butadiene rubber
* PTFE: Polytetrafluoroethylene

As shown in Table 2, the use of butadiene-styrene-butyl methacrylate copolymer (BSB) was superior to the use of styrene-butadiene rubber (SBR) or polytetrafluoroethylene (PTFE) Capacity and resistance characteristics.

In comparison with Examples 9 and 18, it can be seen that the electrostatic capacity and the resistance characteristics are improved in the rolling rolling at normal temperature (Example 18) than in the rolling rolling at a high temperature (150 ° C) .

On the other hand, the interlayer adhesion (90 degree peel test) between the Al etched foil and the activated carbon electrode was evaluated for the electrode sheet (Al etched foil + laminated sheet of activated carbon electrode) according to Examples 9-17. The results are shown in the attached Fig.

As shown in FIG. 7, the higher the content of the binder, the greater the interlayer adhesion. Particularly, in the case of using the butadiene-styrene-butyl methacrylate copolymer (BSB) in the same content, the interlayer adhesion is superior to that in the case of using styrene-butadiene rubber (SBR) or polytetrafluoroethylene (PTFE) Able to know.

As can be seen from the above experimental example, when the metal oxide film layer (Al oxide film layer) is formed on the metal current collector (Al etched foil), it is found that it has excellent electrical characteristics (such as high capacity).

When a nano-particle butadiene-styrene-alkyl methacrylate copolymer is used as a binder, interlayer adhesion and electrode density are improved to have excellent electrical properties (such as high capacity and low resistance) It can be seen that the resistance increase rate leads to long-term reliability and the like.

In addition, it can be seen that, in the case of forming the activated carbon electrode, rolling rolling at room temperature is more advantageous in electrical characteristics than rolling rolling at a high temperature (for example, 150 ° C).

10: anode 20: cathode
12, 22: metal current collectors 12a, 22a: metal oxide film layers
14, 24: activated carbon electrode 15, 25: terminal
30: separator 50: tape
100: electrode body 200: housing
a: concave and convex structure R: roller

Claims (8)

delete delete anode;
cathode;
Electrolytic solution; And
And a separator interposed between the positive electrode and the negative electrode,
At least one selected from the positive electrode and the negative electrode,
A metal current collector, and an activated carbon electrode formed on the metal current collector,
Wherein the metal current collector includes a metal oxide layer formed by oxidation on a surface bonded to an activated carbon electrode,
Wherein the activated carbon electrode comprises activated carbon, a binder and a conductive material,
Wherein the binder comprises carboxymethylcellulose and a butadiene-styrene-alkyl methacrylate copolymer,
Wherein the metal current collector is a metal etching foil having a thickness of 5 占 퐉 to 12 占 퐉,
Wherein the metal oxide film layer has a thickness of 1 탆 to 5 탆,
The activated carbon is activated by steam and has an average particle size of 5 mu m to 30 mu m and a specific surface area of 1500 to 2500 m2 / g,
The binder contains carboxymethylcellulose and a butadiene-styrene-alkyl methacrylate copolymer in a weight ratio of 1: 0.2 to 5,
Wherein said butadiene-styrene-alkyl methacrylate copolymer has an average particle size of 80 nm to 230 nm.
delete delete delete Preparing an anode;
Preparing a cathode;
Obtaining a laminate including a separator between the anode and the cathode; And
Impregnating the laminate with an electrolytic solution,
Wherein the step of preparing the positive electrode and the step of preparing the negative electrode comprise:
A) a step (a) of immersing the metal current collector in an electrolytic aqueous solution and then forming the metal current collector on the surface of the metal current collector by applying a voltage to the positive electrode (+); And
(B) forming an activated carbon electrode on the metal oxide film layer,
The step (a) of forming the metal oxide film layer comprises:
Wherein a metal foil having a thickness of 5 to 12 m is used as the metal current collector,
An electrolytic aqueous solution containing perchloric acid (HClO 4 ) and oxalic acid (C 2 H 2 O 4 ) is used as the electrolytic aqueous solution to form a metal oxide film layer having a thickness of 1 μm to 5 μm,
(B) forming the activated carbon electrode,
An activated carbon electrode composition comprising activated carbon, a binder and a conductive material is used,
The activated carbon is activated by steam and uses activated carbon having an average particle size of 5 to 30 μm and a specific surface area of 1,500 to 2,500 m 2 / g,
Wherein the binder is a binder containing carboxymethyl cellulose and butadiene-styrene-alkyl methacrylate copolymer in a weight ratio of 1: 0.2 to 5,
Wherein the butadiene-styrene-alkyl methacrylate copolymer has an average particle size of 80 nm to 230 nm.
8. The method of claim 7,
(B) forming the activated carbon electrode,
An activated carbon electrode composition including activated carbon, a binder and a conductive material is formed into a sheet, and the sheet is rolled and rolled on a metal oxide layer of a metal current collector to form an activated carbon electrode,
An activated carbon electrode composition comprising activated carbon, a binder and a conductive material is coated on the metal oxide layer of the metal current collector, followed by rolling to form an activated carbon electrode,
Wherein the rolling is performed at room temperature. &Lt; RTI ID = 0.0 &gt; 11. &lt; / RTI &gt;
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