TW201743339A - Conductive composition, electrode and electrochemical double layer capacitor formed therefrom - Google Patents

Abstract

The present invention provides a conductive composition comprising a first activated carbon, a conductive material, polytetrafluoroethylene (PTFE), a water-soluble adhesive, a water-soluble thickening agent and water. The first activated carbon has a specific median of a particle size, as well as percentages of ultramicropores, micropores and mesopores. An electrode and an electrochemical double layer capacitor (EDLC) produced by the conductive composition have a high energy density, a high power density, a high capacity and a low resistance.

Description

Conductive composition, electric double layer capacitor electrode and electric double layer capacitance

The invention relates to a conductive composition, an electric double layer capacitor electrode and an electric double layer capacitor, and in particular to an activity having a specific particle size median and a specific ultramicroporosity, microporosity and mesoporosity. A conductive composition of carbon, and an electric double layer capacitor electrode and an electric double layer capacitor obtained by using the above composition.

Recently, double-layer capacitors with high energy density have largely replaced traditional electrolytic capacitors, which are commonly used in the market. In order to further enhance the efficacy of the electric double layer capacitor, how to reduce its DC impedance and / or increase its capacitance is a problem that is currently actively studied and solved.

One of the currently known methods is to provide a carbonaceous slurry formulation of a specific composition ratio comprising activated carbon, conductive carbon, polytetrafluoroethylene, water-soluble adhesive rubber, water-soluble thickener and water, and The above carbonaceous slurry formulation is formed by a specific manufacturing method. Applying the above carbonaceous slurry formulation to a conductive substrate to form an electrode having a conductive layer, which may have good Flexibility to avoid the disadvantage of cracks in the conductive layer when manufacturing electric double layer capacitors. However, the DC resistance of the electric double layer capacitor electrode obtained by the above method is too high to meet the standards required by the current industry.

Another method is to provide an electrode sheet formulation comprising activated carbon, conductive carbon, polytetrafluoroethylene, water-soluble adhesive rubber and water-soluble thickener, wherein the activated carbon is active with two different average particle sizes. Carbon, and defines a particle size that is three times or more larger than those having a small particle size. Further, it is particularly preferred to add a small particle size of activated carbon in the preparation of the above electrode sheet formulation. Still another method provides the electrode sheet formulation composition as described above, except that it further defines the ratio of the amount of activated carbon having a large particle size to the amount of activated carbon having a small particle size. The above two methods use cellulose-based activated carbon having a high mesoporosity (70% to 99%) to lower the DC resistance and increase the power density. However, the electric double layer capacitor obtained by the above method cannot have a high electric capacity.

There is still another method for utilizing a carbon material having a microcrystalline structure as a precursor of activated carbon, the microcrystalline structure having a layered structure such as graphite, and the activated carbon formed by the activation treatment may have a ratio of less than 300 m ² /g. The surface area can be used as a material for an electric double layer capacitor electrode and can be applied to both positive and negative electrodes of an electric double layer capacitor. However, this method has a small specific surface area and cannot achieve a predetermined capacitance.

In another method, a carbon material which is difficult to graphitize is used as a precursor of activated carbon, and the carbon material is activated by physical activation of water vapor. In this method, the median diameter of the activated carbon may be between 4 μm and 8 μm, and the adsorption amount of the above activated carbon to benzene may be from 47% by weight to 60% by weight. However, the electric double layer capacitor electrode obtained by using the activated carbon of this method is still A good DC impedance cannot be achieved.

In addition, there is a method in which a composite formulation of two activated carbons is used as a raw material of a conductive layer of an electric double layer capacitor electrode, and the activated carbon is a mesophase pitch activated carbon obtained by an alkali chemical activation method, which respectively have different average values. The particle size and the difference in specific surface area are large. After mixing the above-mentioned two kinds of activated carbon, the range of specific surface area falls between about 900m ² / g to 1900m ² / g. The electric double layer capacitor electrode produced by the above activated carbon composite formulation cannot achieve good capacitance and DC impedance.

Therefore, it is urgent to propose a conductive composition and apply it to fabricate an electric double layer capacitor electrode and an electric double layer capacitor having good energy density, power density, high capacitance, and low DC resistance.

Therefore, one aspect of the present invention provides an electrically conductive composition which utilizes activated carbon having a specific particle size and a specific ultramicroporosity, microporosity, and mesoporosity to have high power density and high The advantages of energy density, high capacitance and low DC impedance.

Another aspect of the present invention provides an electric double layer capacitor electrode comprising a conductive layer formed of the above-described conductive composition.

Yet another aspect of the present invention provides an electric double layer capacitor comprising the above described electric double layer capacitor electrode.

According to the above aspect of the invention, a conductive composition is proposed. In an embodiment, the electrically conductive composition may comprise a first activated carbon, a conductive material, a polytetrafluoroethylene, a water soluble adhesive, a water soluble thickener, and water. Above An activated carbon may have a median diameter of 3 μm to 20 μm, a first microporosity of the first activated carbon may be 40% to 70%, and a first microporosity of the first activated carbon and the first mesopores The sum of the rates is 30% to 60%. The amount of the conductive material used is 10 parts by weight to 32 parts by weight, the amount of the polytetrafluoroethylene used is 1 part by weight to 12 parts by weight, and the amount of the water-soluble adhesive is used, based on 100 parts by weight of the first activated carbon. The amount is from 1 part by weight to 12 parts by weight, and the water-soluble thickener is used in an amount of from 0.5 part by weight to 3 parts by weight.

According to an embodiment of the present invention, the conductive composition may further comprise a second activated carbon, wherein the second activated carbon may have a median particle size as described above, and the second ultrafine porosity of the second activated carbon may be From 20% to less than 40%, the sum of the second microporosity of the second activated carbon and the second mesoporosity may be greater than 60% to 80%.

According to an embodiment of the present invention, the second activated carbon may be used in an amount of from 14 parts by weight to 33 parts by weight based on 100 parts by weight of the first activated carbon.

According to an embodiment of the invention, the first microporosity and the second microporosity are calculated by using a first hole having a first pore diameter of less than 0.75 nanometers (nm), the first microporosity and the second micro The porosity is calculated as a second hole having a second pore diameter of 0.75 nm to 1.1 nm, and the first mesoporosity and the second mesoporosity are calculated as a third hole having a third pore diameter greater than 1.1 nm.

According to an embodiment of the present invention, the first total specific surface area of the first activated carbon may be from 1400 m ² /g to 2000 m ² /g.

According to an embodiment of the invention, the second total specific surface area of the second activated carbon may be greater than 2000 m ² /g.

According to an embodiment of the invention, the first activated carbon and the second activated carbon may be alkali activated activated carbon.

According to an embodiment of the present invention, the water may be used in an amount of from 300 parts by weight to 500 parts by weight based on 100 parts by weight of the first activated carbon.

According to an embodiment of the invention, the conductive material comprises a conductive polymer, a conductive carbon material, or any combination thereof.

According to the above aspect of the invention, an electric double layer capacitor electrode is proposed. In one embodiment, the electric double layer capacitor electrode may include a conductive substrate and a conductive layer, and the conductive layer is disposed on at least one surface of the conductive substrate. Wherein, the conductive layer may be formed by the above-mentioned activated carbon composition through a coating step, a drying step, and a rolling step.

According to the above aspect of the invention, an electric double layer capacitor is proposed. In an embodiment, the electric double layer capacitor may include the foregoing electric double layer capacitor electrode and an electrolyte.

According to an embodiment of the present invention, the above electrolyte may include an electrolyte and an organic solvent. The above electrolyte may comprise tetraethylammonium tetrafluoroborate or triethylmethylammonium tetrafluoroborate, and the above organic solvent may comprise acetonitrile or propylene carbonate.

According to an embodiment of the invention, the electric double layer capacitor may comprise a can type electric double layer capacitor or a button type electric double layer capacitor.

The electroconductive composition of the present invention can be obtained by using activated carbon having a specific particle diameter and a specific ultramicroporosity, microporosity and mesoporosity, and the resulting electric double layer capacitor electrode and the above Electrode double layer It has the advantages of high power density, high energy density, high capacitance and low DC impedance.

The present invention provides a conductive composition which may comprise a first activated carbon, a conductive material, a polytetrafluoroethylene, a water-soluble adhesive, a water-soluble thickener, and water. The above conductive composition may utilize an electric double layer capacitor electrode having a specific particle diameter and a specific super microporosity, a microporosity, and a mesoporosity, to obtain an electric double layer capacitor electrode and a conductive composition. Double layer capacitors combine the advantages of high power density, high energy density, high capacitance and low DC impedance. The conductive composition of the present invention will be separately described below.

The ultramicroporosity referred to herein as the ratio refers to the ratio of the total surface area occupied by the ultramicropores on the surface of the activated carbon. The ultramicropores refer to pores having a pore diameter of less than 0.75 nanometers (nm).

The microporosity referred to herein as the ratio of the total surface area occupied by the micropores on the surface of the activated carbon. The micropores refer to pores having a pore diameter of 0.75 nm to 1.1 nm.

The term "porosity" as used herein refers to the ratio of the total surface area occupied by mesopores on the surface of activated carbon. The mesoporous refers to a pore having a pore diameter greater than 1.1 nm. Preferably, the pore size of the mesopores is greater than 1.1 nm to 5.0 nm.

The median particle size referred to herein as used herein refers to the Among the particle diameters of activated carbon, the particle size of the largest distribution is not necessarily the same as the average particle diameter.

Conductive composition First activated carbon

The first activated carbon referred to herein may have a median diameter of 3 μm to 20 μm, the first ultramicroporosity of the first activated carbon may be 40% to 70%, and the first micro-first carbon The sum of the porosity and the first mesoporosity is 30% to 60%.

In one embodiment, the first activated carbon may have a total specific surface area of 1400 m ² /g to 2000 m ² /g, wherein the total specific surface area is a density functional theory measured by isothermal adsorption of nitrogen (Density Functional Theory) ; DFT) or BET theory (Brunauer-Emmett-Teller Theory; BET) measured.

In one embodiment, the first activated carbon may be an alkali activated activated carbon. Specifically, the activated carbon may be formed by using a coal tar pitch as a precursor and performing pore formation by an alkali chemical activation method to obtain a specific ultramicroporosity, microporosity, and mesoporosity ratio as described above. An activated carbon. In one example, the above alkali chemical activation method is carried out using potassium hydroxide as an activator. The alkali chemical activation method should be a technique well known to those skilled in the art and will not be described here.

Specifically, the above-mentioned first activated carbon may be a product manufactured by Sinosteel Carbon Chemical Company under the names of ACS 15 and ACS 20.

In particular, ultra-micropores with small pore sizes can provide larger Capacitance, however, because the small aperture affects the diffusion of ions, the DC impedance is large. On the other hand, micropores and mesopores with large pore sizes provide less capacitance, but large pore sizes contribute to ion diffusion and thus help reduce DC impedance. Therefore, the present invention can utilize the ratio of the micropores of the specific composition to the micropores and mesopores, so that the prepared electric double layer capacitor electrodes and the electric double layer capacitors can have high energy density, high power density, and high power. Capacity and low DC impedance.

Therefore, if the first ultramicroporosity of the first activated carbon is less than 40% or the sum of the first microporosity and the first mesoporosity is higher than 60%, the obtained electric double layer capacitor electrode cannot be effectively improved. And the capacitance of the electric double layer capacitor. On the other hand, if the first ultra-microporosity of the first activated carbon is higher than 70% or the sum of the first mesoporosity is less than 30%, the electric double layer capacitor electrode and the electric double layer capacitor are obtained. The DC impedance difference.

Conductive material

In one embodiment, the electrically conductive material referred to herein as the conductive material may comprise a conductive polymer, a conductive carbon material, or any combination thereof. In a specific example, the conductive polymer may be, for example, poly(acetylene); PAC, poly(p-phenylene vinylene); PPV, or may or may not contain impurities. Aromatic polycyclic ring of atoms. The hetero atom may be a nitrogen atom or a sulfur atom.

Polyaromatic ring groups containing no heteroatoms may include, but are not limited to, polyfluorenes, polypyrenes, polynaphthalenes, or polyazulenes.

Polyaromatics containing nitrogen atoms may include, but are not limited to, polyanilines (polyanilines; PANI), polypyrroles (PPY) polypyrollidines, polycarbazoles, polyindoles.

The polyaromatic ring family containing sulfur atoms may include, but is not limited to, polythiophenes. The above polythiophenes may, for example, be poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (abbreviated as PEDOT:PSS), poly(3,4-ethylenedioxythiophene) [Poly ( 3,4-ethylenedioxythiophene); PEDOT] or poly(styrenesulfonate); PSS].

The above conductive polymers may be used singly or in combination.

In another specific example, the conductive carbon material may be, for example, conductive carbon black, graphite, graphene, nano carbon fiber or carbon nanotube, wherein the type of graphite is, for example but not limited to, flake, granular, agglomerate or Tubular.

In one embodiment, the conductive material may be used in an amount of 10 parts by weight to 32 parts by weight based on 100 parts by weight of the first activated carbon.

In particular, the conductive material helps to increase the conductivity of the conductive composition. When the conductive composition is applied to the electric double layer capacitor electrode and the electric double layer capacitor, the addition of the conductive material helps to reduce the DC resistance. However, the conductive material does not contribute to the capacitance. Therefore, if the amount of the conductive material used is less than 10 parts by weight, the direct current impedance of the conductive composition is too high. On the other hand, if the amount of the conductive material used is more than 32 parts by weight, the capacity of the first activated carbon is relatively reduced, resulting in loss of capacitance.

PTFE

The type and nature of the polytetrafluoroethylene referred to herein as There is no particular limitation. In a specific example, the polytetrafluoroethylene may be, for example, modified or unmodified polytetrafluoroethylene, and the polytetrafluoroethylene may be polytetrafluoroethylene particles or polytetrafluoroethylene fibers. . Preferably, the polytetrafluoroethylene particles have an average particle diameter of 10 μm or less, more preferably 1 μm or less.

In one embodiment, the polytetrafluoroethylene may be used in an amount of from 1 part by weight to 12 parts by weight based on 100 parts by weight of the first activated carbon.

In one example, the polytetrafluoroethylene is a polytetrafluoroethylene particle, and in the method for producing an activated carbon composition described later, the polytetrafluoroethylene particles may pass through a shearing force (Shear Force) and the first activated carbon described above. The second activated carbon to be described later generates friction and is further converted into a polytetrafluoroethylene fiber (for details, please refer to later). The aforementioned specific average particle diameter (10 μm or less) contributes to the conversion of the polytetrafluoroethylene particles into polytetrafluoroethylene fibers.

In the conductive composition, the above polytetrafluoroethylene fiber can provide good flexibility and toughness. Further, when the conductive layer of the present invention is used to form a conductive layer, cracks are generated at the winding portion of the electric double layer capacitor electrode. However, it is also possible to use polytetrafluoroethylene particles directly.

Therefore, when the amount of polytetrafluoroethylene used is less than 1 part by weight, the formed conductive layer is insufficient in flexibility and toughness. On the other hand, if the amount of polytetrafluoroethylene used is more than 12 parts by weight, the direct current impedance of the conductive layer is increased.

Water soluble adhesive

The water-soluble adhesive referred to herein as the water-soluble adhesive may comprise a water-soluble adhesive rubber. Specifically, the above water-soluble adhesive rubber may be natural rubber Glue, synthetic rubber or a combination of the above.

In a specific example, the above synthetic rubber may include, but is not limited to, a styrenic block copolymer, polyisobutylene, or a combination thereof. The aforementioned styrenic block copolymer may be, for example, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene. - ethylene/butadiene-styrene block copolymer (SEBS), styrene-ethylene/propylene-styrene block copolymer (SEPS).

Specific examples of the above styrene block copolymer may be, for example, those manufactured by KRATONPOLYMER Co., Ltd. under the trade names of KRATON D-1112, D-1llU D-1107, KRAT0N D-KX401CS or D-1107CU, Japanese synthetic rubber ( A product of the trade name TRD-102A, JSR5000 or JSR5002, a linear block copolymer such as a product of the Japanese ZEON Co., Ltd. under the trade name Quintac3530, 3421 or 3570C, and a product made by POLYMER. A product called KRATON D-1124, a graft block copolymer of Phillips Petroleum, which is marketed under the trade name Solprene 418.

In one embodiment, the water-soluble adhesive may be used in an amount of from 1 part by weight to 12 parts by weight based on 100 parts by weight of the first activated carbon.

The water-soluble adhesive referred to herein helps to increase the adhesion between the conductive layer formed by the conductive composition and the conductive substrate. Further, the water-soluble adhesive can make the conductive layer and the conductive substrate difficult to separate when the electric double layer capacitor electrode is wound.

Therefore, if the above water-soluble adhesive is used in an amount less than 1 weight In this case, the adhesion between the conductive layer and the conductive substrate is poor and easy to separate. On the other hand, if the amount of the above water-soluble adhesive is more than 12 parts by weight, the direct current impedance of the conductive layer is increased.

Water soluble thickener

The water-soluble thickener referred to herein as the water-soluble thickener has no limitation on the use, and it is preferred that it is miscible with water. Specifically, the water-soluble thickener may be, for example, sodium carboxymethylcellulose, an ammonium salt of carboxymethylcellulose, methylcellulose or hydroxypropylcellulose. Preferably, the above water-soluble thickener may be sodium carboxymethylcellulose. The above water-soluble thickeners may be used singly or in combination.

In one embodiment, the water-soluble thickener may be used in an amount of from 0.5 part by weight to 3 parts by weight based on 100 parts by weight of the first activated carbon.

The water-soluble thickener referred to herein has the effects of thickening and Thixotropic, so that the conductive composition of the present invention can be prevented from being separated or precipitated upon standing storage. Further, the water-soluble thickener can stably form the conductive layer formed of the conductive composition on the conductive substrate. In one example, the water soluble thickener increases the viscosity of the electrically conductive composition to prevent the aforementioned polytetrafluoroethylene particles from floating on the liquid surface and affecting the proportion of the polytetrafluoroethylene fibers.

Therefore, if the above water-soluble thickener is used in an amount of less than 0.5 part by weight, the thickening effect is not obtained. On the other hand, if the above-mentioned water-soluble thickener is used in an amount of more than 3 parts by weight, the viscosity of the conductive composition is too high, so that the other components of the conductive composition are not uniformly dispersed.

water

The water herein is not limited in kind, and specifically, for example, distilled water, deionized water, pure water, reverse osmosis water or any combination of the above may be used.

In one embodiment, water may be used in an amount of from 300 parts by weight to 500 parts by weight based on 100 parts by weight of the first conductive composition.

Second activated carbon

The conductive composition of the present invention may further comprise a second activated carbon which may have the same median particle size as the first activated carbon (i.e., 3 μm to 20 μm). The second ultraporosity of the second activated carbon may be from 20% to less than 40%, and the sum of the second microporosity of the second activated carbon and the second mesoporosity may be greater than 60% to 80%.

In one embodiment, the second activated carbon may have a total specific surface area greater than 2000 m ² /g. Further, the second activated carbon referred to herein as the first activated carbon may be an alkali activated activated carbon. The specific content of the alkali activated activated carbon has been specifically described in the paragraph of the aforementioned first activated carbon, and will not be further described herein. Specifically, the second activated carbon may be a product of the model ACS 25 manufactured by Sinosteel Carbon Co., Ltd.

In one embodiment, the second activated carbon may be used in an amount of from 14 parts by weight to 33 parts by weight based on 100 parts by weight of the first activated carbon.

The second active carbon of the present invention has a higher sum of microporosity and mesoporosity, thereby contributing to a reduction in the direct current impedance of the produced electric double layer capacitor electrode and the electric double layer capacitor. If the amount of the second activated carbon used is less than 14 parts by weight, the help for the direct current impedance of the electric double layer capacitor electrode and the electric double layer capacitor is limited. On the other hand, if the amount of the second activated carbon used is more than 33 parts by weight, since the influence of the second activated carbon on the capacitance is less than that of the first activated carbon, the excessive second activated carbon causes the electric double layer capacitance. The capacitance of the electrodes and the electric double layer capacitors decreases.

In one example, when the first activated carbon and the second activated carbon are simultaneously present in the conductive composition, the median diameters of the two are the same or similar. If the median diameter of the two is far apart (for example, the median difference between the two particles is 1.5 times or more), the manufacturing difficulty of the conductive composition is increased, and the manufacturing cost is increased.

Method for producing conductive composition

Hereinafter, a method of producing the electrically conductive composition of the present invention will be specifically described. In one embodiment, water, a water soluble thickener, and polytetrafluoroethylene particles are first mixed. Next, the first activated carbon (or the second activated carbon) is added and uniformly mixed with the aforementioned materials. Then, a shearing force is provided to cause the aforementioned polytetrafluoroethylene particles to rub with the first activated carbon (or the added second activated carbon), so that the polytetrafluoroethylene particles are converted into polytetrafluoroethylene fibers to form a conductive Composition.

In one example, the water-soluble adhesive may be added before or after the shearing force is provided, but it is preferred to add it after providing a shearing force. In mention The addition of a water-soluble adhesive after shearing forces contributes to the formation of fibrous polytetrafluoroethylene.

In yet another example, the electrically conductive material can be added after mixing the water, the water soluble thickener, and the polytetrafluoroethylene particles, and prior to providing the shearing force.

The above-described method of providing the shearing force can be, for example, a step of performing mixing and stirring using a stirrer having a disk type stirring blade or a high-speed emulsifier. The progress time and the magnitude of the force of the above-described mixing and stirring step are determined depending on the total amount of the conductive composition, and are not particularly limited herein.

In particular, although the method for producing the conductive composition of the present invention uses polytetrafluoroethylene particles and forms a polytetrafluoroethylene fiber by shearing force, in other embodiments, the polytetrafluoroethylene fiber can also be used directly. Fluoroethylene fibers, or directly blending polytetrafluoroethylene particles with other components of the conductive composition without forming polytetrafluoroethylene fibers. The above-mentioned changes do not depart from the scope and spirit of the present invention, and do not substantially affect the intended effects of the present invention. Therefore, those having ordinary knowledge in the art should be able to perform the above-mentioned contents according to the disclosure of the present invention. Retouching.

Electric double layer capacitor electrode and manufacturing method thereof

Hereinafter, the electric double layer capacitor electrode of the present invention and a method of manufacturing the same will be specifically described. In one embodiment, the aforementioned conductive composition is first applied to a conductive substrate. Then, the above-mentioned conductive substrate coated with the conductive composition is dried. Thereafter, the conductive substrate is subjected to a rolling step to form a conductive layer on the conductive substrate, and the electric double layer capacitor electrode can be obtained. In an example, the fabricated double layer capacitor electrode can be used as the positive electrode in the electric double layer capacitor. Polar or negative electrode.

The aforementioned conductive substrate may be, for example, a metal foil. Specifically, the material of the above metal foil may include, but not limited to, stainless steel, gold, silver, copper, molybdenum, aluminum, titanium, or any combination thereof.

The coating step is not particularly limited, and specifically, roll coating, spray coating, blade coating, slit coating, dip coating, or the like can be used.

The aforementioned drying step can be carried out, for example, at a temperature of from 40 ° C to 100 ° C. Further, the drying step can be carried out, for example, by hot air drying, infrared drying or microwave drying.

The aforementioned rolling step can be carried out, for example, at a temperature of from 25 ° C to 150 ° C. If the temperature of the rolling step is higher than 150 ° C, the adhesion of the water-soluble adhesive in the conductive composition is affected.

The thickness of the above conductive substrate may be, for example, 5 μm to 30 μm, and the thickness of the conductive composition coated on the conductive substrate may be, for example, 5 μm to 100 μm.

Electric double layer capacitor

The electric double layer capacitor of the present invention may comprise the aforementioned electric double layer capacitor electrode and an electrolyte. In one example, the concentration of the above electrolyte may be from 1 M to 2 M.

Specifically, the above electrolyte solution may contain an electrolyte and an organic solvent. The electrolyte may, for example, comprise Tetraethylammonium tetrafluoroborate (TEABF ₄ ) or Triethylmethylammonium tetrafluoroborate (TEMABF ₄ ), and the organic solvent may, for example, comprise acetonitrile (ACN) or carbonic acid. Propylene carbonate (PC).

In addition, the size of tetraethylammonium ion (TEA ⁺ ) is about 0.343 nm, the size of triethylmethylammonium ion (TEMA ⁺ ) is about 0.327 nm, and the size of tetrafluoroboric acid ion (BF ₄ ^- ). It is about 0.24 nm, and the size of the tetraethylammonium ion-adsorbed acetonitrile polymerized ion (TEA ⁺ ‧7 ACN) is about 0.68 nm. The pore size of the above-mentioned ultramicropores, micropores and mesopores of the present invention is defined by the above-mentioned tetraethylammonium ion-adsorbed acetonitrile polymerization ion.

In a specific example, the electric double layer capacitor of the present invention may comprise a canister type electric double layer capacitor having a capacitance of 1 farad (F), a button type electric double layer capacitor having a capacitance of 0.4 F, or other common electric double layer. capacitance.

Hereinafter, the manufacturing method and efficacy of the conductive composition, the electric double layer capacitor electrode, and the electric double layer capacitor of the present invention will be specifically described using a plurality of examples.

Preparation of conductive composition Preparation Example 1

3 parts by weight of sodium carboxymethylcellulose (manufactured by Daiichi Kogyo; model number H-1496A), 350 parts by weight of water, and 6 parts by weight of polytetrafluoroethylene particles (manufactured by Sigma-Aldrich; CAS No. 9002) -84-0) Add a mixer with a disc mixing blade (DC mixer made by IKA® EUROSTAR Digital, No. 10 for mixing blades, 40 mm for 40 mm). Next, 10 parts by weight of conductive carbon (manufactured by Timcal Co., Ltd.; trade name: Super P ^® ) and 100 parts by weight of activated carbon (manufactured by Sinosteel Carbon Co., Ltd.; model: ACS 15) were added. Then, the mixture was stirred for 1 hour by the aforementioned agitator, and 6 parts by weight of polystyrene-butadiene rubber (manufactured by JSR; model: TRD-102A, solid content: 48% by weight) was added and uniformly mixed to prepare Preparation Example 1 Conductive composition. The specific specifications of the activated carbon used in the preparation examples are shown in Table 1.

Preparation Examples 2 to 5 and Preparation Comparative Example 1

Preparation Examples 2 to 5 and Preparation Comparative Example 1 were carried out in the same manner as in Preparation Example 1, except that Preparation Examples 2 to 5 and Preparation Comparative Example 1 were used to change the types of the respective components in the conductive composition used and/or The specific components of Preparation Examples 2 to 5 and Preparation Comparative Example 1 are shown in Table 1 and Table 2, and are not described herein.

Example 1

The conductive composition of the above Preparation Example 1 was applied onto an aluminum sheet having a thickness of 30 μm, and the coating thickness was 100 μm, and dried at 85 ° C with hot air. Thereafter, rolling was further carried out at 80 ° C to form a conductive layer on the aluminum sheet, thereby producing an electric double layer capacitor electrode.

The electric double layer capacitor electrode is used as a positive electrode and a negative electrode of an electric double layer capacitor, and the positive electrode and the negative electrode are separated by a cellulose separator, and packaged into a can electric double layer of the first embodiment having a capacitance of 1F. A capacitor in which 1 M tetraethylammonium tetrafluoroborate (TEABF ₄ /ACN) dissolved in acetonitrile was used as an electrolyte. 50 pot-type electric double layer capacitors of the above-mentioned Example 1 were taken, and the tests of capacitance, DC impedance, energy density, and power density were repeated to obtain an average value of the above evaluation methods. The specific test results of the embodiment 1 are as shown in Table 3, and are not described here.

Examples 2 to 8

Examples 2 to 8 were carried out in the same manner as in Example 1, except that Examples 2 to 8 were changed in the conductive composition, electrolytic solution or package form used. The specific conditions of the embodiments 2 to 8 are as shown in Table 3, and are not described herein.

Comparative Examples 1 to 3

Comparative Examples 1 to 3 used commercially available electric double layer capacitors, and tested for capacitance, DC resistance, energy density, and power density in the same electrolyte as in the present invention, and the conditions and evaluation results are shown in Table 3. Show, no further details here.

Comparative Examples 4 to 5

Comparative Examples 4 to 5 were carried out in the same manner as in Example 1, except that Comparative Examples 4 to 5 were changed in the conductive composition, electrolytic solution or package form used. The specific conditions for Comparative Examples 4 to 5 are shown in Table 3 and will not be further described herein.

In addition, if the package is a button type electric double layer capacitor, the area of the positive electrode and the negative electrode is 1.3273 cm ² and is isolated by a cellulose separator.

Evaluation method Capacitance

The capacitance referred to herein as the capacitance refers to the median capacitance of the 50 electric double layer capacitors sampled. In general, the higher the capacitance, the better, and 1.2F is the lower limit of the capacitance. The above-mentioned capacitance is measured by 10% of the capacity as DC charging and discharging current. For example, the 1F electric double layer capacitor is 0.1A, the saturated charging voltage is 2.7V, and the discharge target voltage is 1.35V, and according to the following formula (I) Calculating the capacitance of the embodiment and the comparative example: capacitance (C; unit is Farah (F)) = 2 × I × Δt / ΔV (I)

Where I is the discharge current, the unit is Ampere (A); Δt is the time when the electric double layer capacitor discharges from the saturated charging voltage to the discharge target voltage, and its unit is the second (sec) potential difference; ΔV is the saturated charging voltage discharge and The voltage difference between the discharge target voltages, in volts (V).

2. DC impedance

The DC impedance referred to herein is the median DC resistance of the 50 electric double layer capacitors sampled. In general, the lower the DC resistance, the better. The above DC impedance is measured by 10% of the capacitance as the DC charging and discharging current. For example, the 1F electric double layer capacitor is 0.1A, and the 2.7V saturated charging voltage is discharged to the target voltage of 1.35V for 7 seconds. The rebound amount is calculated as follows (II): DC impedance (ESR _DC ; unit is ohm (Ω)) = ΔV/I (II)

Where I is the discharge current, the unit is ampere (A); ΔV is the voltage difference between the saturated charge voltage discharge and the discharge target voltage, and the unit is volt (V).

3. Energy density (E _Max )

The term "energy density" as used herein refers to the amount of energy stored in a given space or mass of matter, in watt hours (Wh) per kilogram (Kg). In general, the higher the energy density, the better, and the energy density is calculated according to the following formula (III): energy density (unit: Wh/kg) = (0.5 × CV ² ) / (3600 × w) (III)

Where C is the capacitance and its unit is Farah (F); V is the rated voltage of the electric double layer capacitor of 2.7V, w is the electric double layer capacitance, and the constant term 3600 is converted to watt by Joule. Hour (Wh) required.

4. Power density (P _Max )

The power density referred to herein as "power density" refers to the power per unit volume in units of watts (W) per kilogram (kg). In general, the higher the power density, the better, and the power density is calculated according to the following formula (IV): Power density (in W/kg) = V ² / (4 × ESR _DC × w) (IV)

Where V is the rated voltage of the electric double layer capacitor of 2.7V, ESR _DC is the DC impedance of the electric double layer capacitor, and w is the electric double layer capacitance.

It can be seen from Tables 1 to 3 that in the case of the 1F can type electric double layer capacitor (with TEABF ₄ /ACN as the electrolyte), the first to fourth embodiments of the present invention can be achieved with Comparative Example 1 (i.e., commercially available). The electric double layer capacitor electrode) has comparable energy density, power density, capacitance, and DC impedance. Further, in Example 2, activated carbon having a high ultraporosity (ACS 20) was used, so that the surface of the capacitance was superior to that of the activated carbon (ACS 15) used in Example 1, but the DC resistance was slightly higher than that. Example 1. Further, as is apparent from Examples 3 and 4, in order to compensate for the DC resistance described above, the amount of the conductive material added can be increased, and the DC resistance of the obtained electric double layer capacitor can be further reduced, but the capacitance is not substantially affected.

Next, in the case of the 1F can type electric double layer capacitor (with TEMABF ₄ /ACN as the electrolyte), the inventive examples 5 and 6 can also be compared with the comparative example 2 of the commercially available electric double layer capacitor electrode. More excellent results. Further, Example 6 using activated carbon having a higher ultramicroporosity can have better electric capacity and lower DC resistance than in Example 5.

Examples 7 and 8 are examples of a 0.4F button type electric double layer capacitor package in which TEABF ₄ /ACN is used as an electrolyte. As shown in the evaluation results of Table 3, Examples 7 and 8 achieved a capacitance equivalent to Comparative Example 3 of a commercially available electric double layer capacitor electrode, and the DC resistance was lower than that of Comparative Example 3. In particular, Example 7 uses two activated carbons (ACS 20 and ACS 25) in combination, through the ultra-microporosity and a specific ratio of the sum of microporosity and mesoporosity, so that the resulting electric double layer capacitor It can have both high capacity and low DC resistance, so Example 7 can have better efficacy than Example 8 using an activated carbon component alone.

On the other hand, according to Comparative Examples 4 to 5 of Table 3, if the conductive composition does not include the first activated carbon claimed in the present invention (the ultramicroporosity is 40% to 70%, and the microporosity and the mesopores) The sum of the rates is 30% to 60%), although the electric double layer capacitor can have a lower DC impedance, but the capacitance is lower than the lower limit of the capacitance, so it cannot have both low DC impedance and high capacitance.

In the conductive composition of the present invention, the obtained electric double layer capacitor electrode and electric double layer capacitor can be obtained by using activated carbon having a specific particle diameter and a specific ultramicroporosity, microporosity and mesoporosity. It combines the advantages of high power density, high energy density, high capacitance and low DC resistance.

While the invention has been described above in terms of several embodiments, it is not intended to limit the scope of the invention, and the invention may be practiced in various embodiments without departing from the spirit and scope of the invention. The scope of protection of the present invention is defined by the scope of the appended claims.

Claims (13)

An electroconductive composition comprising: a first activated carbon, wherein the first activated carbon has a median diameter of one of 3 micrometers (μm) to 20 μm, and the first microporosity of the first activated carbon is 40 % to 70%, and the sum of the first microporosity and the first mesoporosity of the first activated carbon is 30% to 60%; a conductive material; polytetrafluoroethylene; a water-soluble adhesive; a water-soluble thickener; and water, wherein the conductive material is used in an amount of 10 parts by weight to 32 parts by weight based on the first activated carbon, and the polytetrafluoroethylene is used in an amount of 1 part by weight. The water-soluble adhesive is used in an amount of from 1 part by weight to 12 parts by weight, and the water-soluble thickener is used in an amount of from 0.5 part by weight to 3 parts by weight to 12 parts by weight. The conductive composition of claim 1, further comprising a second activated carbon, wherein the second activated carbon has a median of the particle diameter, and the second ultramicroporosity of the second activated carbon 20% to less than 40%, and the sum of the second microporosity and the second mesoporosity of the second activated carbon is greater than 60% to 80%. The conductive composition according to claim 2, wherein the first active carbon is used in an amount of 100 parts by weight, the first The amount of the second activated carbon used is from 14 parts by weight to 33 parts by weight. The conductive composition of claim 2, wherein the first ultramicroporosity and the second ultramicroporosity are calculated as a first hole having a first pore diameter of less than 0.75 nanometer (nm). The first microporosity and the second microporosity are calculated by using a second hole having a second pore diameter of 0.75 nm to 1.1 nm, and the first mesoporosity and the second mesoporosity are one A third hole having a third aperture greater than 1.1 nm is calculated. The conductive composition of claim 1, wherein the first total specific surface area of the first activated carbon is from 1400 m ² /g to 2000 m ² /g. The conductive composition of claim 2, wherein the second total specific surface area of the second activated carbon is greater than 2000 m ² /g. The conductive composition of claim 2, wherein the first activated carbon and the second activated carbon are activated activated carbon. The conductive composition according to claim 1, wherein the water is used in an amount of from 300 parts by weight to 500 parts by weight based on 100 parts by weight of the first activated carbon. The conductive composition as described in item 1 of the patent application scope And the conductive material comprises a conductive polymer, a conductive carbon material or any combination thereof. An electric double layer capacitor electrode comprising: a conductive substrate; and a conductive layer disposed on at least one surface of the conductive substrate, wherein the conductive layer is any one of items 1 to 8 of the patent application scope The conductive composition is formed by a coating step, a drying step, and a rolling step. An electric double layer capacitor comprising: the electric double layer capacitor electrode according to claim 10; and an electrolyte. The electric double layer capacitor according to claim 11, wherein the electrolyte comprises an electrolyte and an organic solvent, and the electrolyte comprises tetraethylammonium tetrafluoroborate or triethylmethylammonium tetrafluoroborate. The organic solvent contains acetonitrile or propylene carbonate. The electric double layer capacitor of claim 11, wherein the electric double layer capacitor comprises a can body type electric double layer capacitor or a button type electric double layer capacitor.