JP2008288549A - Collector electrode member for nonaqueous electrical double layer capacitor which is produced by providing undercoat layer on high-purity aluminum plane foil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a collector electrode using an aluminum foil in which voltage resistance is enhanced. <P>SOLUTION: This collector electrode member for a nonaqueous electrical double layer capacitor has a high-purity aluminum plane foil and an undercoat layer formed by coating the surface of the aluminum plane foil with a slurry containing a conducting adjuvant and a latex of a synthetic rubber and by drying the resultant laminate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a collector electrode member of a non-aqueous electric double layer capacitor.

  Electronic parts such as non-aqueous electric double layer capacitors, non-aqueous batteries, and electrolytic capacitors have a configuration in which an electrode member is immersed in an electrolytic solution in which a solute is dissolved in a non-aqueous solvent. An electrode member refers to an assembly that introduces electricity into or removes electricity from an electrolytic cell holding an electrolytic solution. In the present specification, the electrode member refers to a combined body of a collecting electrode and a polarizable electrode.

  A polarizable electrode refers to an electrode that contains an electrode active material and acts on an electrolyte during charge / discharge of an electronic component to cause polarization, and a collecting electrode refers to an electrode that supports a polarizable electrode. As the material of the collector electrode, a good conductor that can sufficiently transfer charges to the polarizable electrode is used. Examples of such good conductors include aluminum, copper, silver, nickel, and titanium. However, from the viewpoint of cost and availability, aluminum is mainly used as the material for the collector electrode.

  When used as a collector electrode, the aluminum is foiled, the surface is roughened, and the surface is bonded to the polarizable electrode layer. The reason for roughening the surface is to increase the surface area of the collector electrode to adhere the polarizable electrode to the collector electrode.

  However, the collector electrode using aluminum foil starts oxidative deterioration when the voltage between the terminals of the electric double layer capacitor exceeds about 3.2 V, and the rated voltage cannot be increased further. On the other hand, electrode active materials that operate at high voltages such as non-porous carbon and graphite are being developed, and the withstand voltage of polarizable electrodes is expected to be further improved. Therefore, it is desired to further improve the withstand voltage of the collector electrode using the aluminum foil.

  Patent Document 1 describes a technique for improving the rated voltage of an electric double layer capacitor using high-purity aluminum as a collecting electrode. However, the maximum value of the rated voltage achieved by this technology is only 2.7V.

  Patent Document 4 describes an electrochemical capacitor manufactured using a current collector made of a metal plain foil. An electrode layer is formed on the surface of the current collector via an anchor coat layer. As the binder constituting the anchor coat layer, an ammonium salt of carboxymethyl cellulose is described. In addition, usable resins are suggested to be water-soluble and hardly water-soluble after drying.

  The technique of Patent Document 4 is characterized by using graphitized carbon black having excellent conductivity instead of general acetylene black or the like as the conductive material of the anchor coat layer. Thus, the resistance of the anchor coat layer is reduced.

  That is, by combining a low-resistance anchor coat layer and a plain foil that is high in strength but difficult to reduce in resistance as compared with an etched foil, the object is to achieve both low resistance and high strength of the electrode.

However, Patent Document 4 does not describe a technique for improving the withstand voltage of the electric double layer capacitor electrode.
JP 2001-176757 A Patent 3889025 JP 2005-286178 A JP 2006-210883 A

  The present invention solves the above-described conventional problems, and an object of the present invention is to improve the withstand voltage of a collector electrode using an aluminum foil.

The present invention provides a high purity aluminum plain foil,
An undercoat layer formed by applying and drying a slurry containing a conductive auxiliary agent and a latex of synthetic rubber on the surface of the aluminum plain foil;
A non-aqueous electric double layer capacitor collecting electrode member having the above object is achieved.

  The collector electrode member of the present invention has a high withstand voltage and low resistance. As a result, even if the rated voltage of the electric double layer capacitor cell is increased, the electrolytic solution is hardly deteriorated, and the cycle characteristics, particularly energy density and durability are improved. Further, since the surface roughening treatment is not performed, the aluminum foil has high physical strength, the electrode member can be made thinner, and the manufacturing cost is low.

  High purity aluminum refers to aluminum in which the content of impurities is reduced. The impurity here refers to a metal element such as copper. The purity of the high-purity aluminum is preferably 99.85% or more, 99.99% or more, or 99.999% or more. When the purity of the high-purity aluminum is less than 99.85%, impurities are eluted from the collector electrode when a voltage is applied, and the voltage holding characteristics of the electric double layer capacitor cell are deteriorated.

  Aluminum plain foil refers to an aluminum foil having no roughening layer on the surface. For example, by removing unnecessary components such as rolling oil from the surface of foil that has been thinned by rolling metal aluminum, and removing rolling oil and surface impurities on the surface by alcohol cleaning, plasma treatment, ozone treatment, UV treatment, etc. An aluminum foil or the like that improves the coatability of a liquid having a large surface tension corresponds to an aluminum plain foil.

  The thickness of the aluminum plain foil is 8 to 50 μm, preferably 10 to 20 μm, more preferably 12 to 15 μm. The aluminum plain foil has a high physical strength because there is no roughening layer on the surface, and can be made thinner than an aluminum foil that has been subjected to a roughening treatment. In general, it is difficult to reduce the thickness of an aluminum foil that has been roughened to a thickness of about 30 μm or less. By thinning the collector electrode, the electrode member is also thinned, the electric double layer capacitor cell can be miniaturized, and the electrode density can be further increased.

  The undercoat layer is provided to adhere the polarizable electrode to the collector electrode and inhibit contact between the aluminum plain foil and the electrolytic solution. The undercoat layer is excellent in the electrolyte barrier property, redox resistance, and chemical resistance, and needs to exhibit good stability over the life of the electric double layer capacitor. Further, the undercoat layer needs to electrically connect the aluminum plain foil and the polarizable electrode layer.

  A preferred material for constituting the undercoat layer is an elastomer in which a conductive auxiliary agent is dispersed. Specific examples of conductive auxiliary agents include graphite having high conductivity due to the presence of delocalized π electrons; carbon black, which is a spherical aggregate in which several layers of graphite carbon microcrystals gather to form a turbulent structure (Acetylene black, ketjen black, other furnace blacks, channel blacks, thermal lamp blacks, etc.); Hydrocarbons such as methane, propane, and acetylene are vapor-phase pyrolyzed and deposited in a thin film on the blackboard as a substrate And pyrolytic graphite. Among them, flaky graphite [particularly natural graphite (scaly graphite)] is also a acetylene because it has a relatively small particle size and a relatively good conductivity because it can ensure high conductivity. Black is preferred.

  The elastomer in which the conductive auxiliary agent is dispersed is preferably a synthetic rubber. Specific examples of the synthetic rubber include isoprene rubbers such as isoprene rubber (polyisoprene); butadiene rubbers such as butadiene rubber (cis-1,4-polybutadiene) and styrene-butadiene rubber (SBR); nitrile rubber (NBR) And diene special rubbers such as chloroprene rubber; olefin rubbers such as ethylene / propylene rubber, ethylene / propylene / diene rubber and acrylic rubber; hydrin rubber; urethane rubber; fluorine rubber;

  Among the above synthetic rubbers, SBR having various varieties is inexpensive and suitable. Furthermore, as SBR, a glass transition temperature (Tg) of −100 ° C. to 0 ° C., particularly −90 ° C. to −70 ° C. is more preferable. Here, the TBR of SBR is a value measured in accordance with JIS-K7121 regulations.

  Of the above synthetic rubbers, latex may be used for those for which latex is easily available. For example, latex such as SBR and NBR is common. In this case, all of the conductive adhesive dispersion medium may be derived from latex, or a dispersion medium may be added separately.

  The content (based on solid content) of the conductive additive in the undercoat layer is, for example, 40 to 90% by mass, 40 to 80% by mass, preferably 45 to 70% by mass, and more preferably 50 to 60% by mass. When the amount of the conductive auxiliary is less than 40% by mass, it is difficult to ensure conductivity, and when it exceeds 90% by mass, the coating property is deteriorated. The content of the synthetic rubber in the undercoat layer is, for example, 10 to 60% by mass, particularly 20 to 60% by mass, preferably 30 to 55% by mass, and more preferably 40 to 50% by mass. When the amount of the synthetic rubber is less than 10% by mass, the coating property is deteriorated, and when it exceeds 60% by mass, it is difficult to ensure conductivity.

  The undercoat layer is formed by applying and drying a liquid (slurry) containing a conductive auxiliary agent, a latex of synthetic rubber and, if necessary, a dispersion medium, on the surface of the aluminum plain foil. The application method is not particularly limited, but is usually applied by a gravure printing method or a die head method. The thickness of the undercoat layer is 1 to 5 μm, preferably 1 to 2 μm in a dry state. When the thickness of the undercoat layer is less than 1 μm, the barrier property of the electrolyte is insufficient, and when it exceeds 5 μm, the conductivity is insufficient.

  The dispersion medium is not particularly limited, but water, lower alcohols (such as methanol, ethanol, n-propanol, and isopropanol), and organic solvents (such as toluene and NMP) are preferable. In this case, all of the slurry dispersion medium may be derived from latex, or a dispersion medium may be added separately.

  Synthetic rubber latex is a stable colloidal dispersion in which synthetic rubber is dispersed in an aqueous medium. This latex preferably comprises an acid-modified latex. Although the reason is not clear, the acid-modified latex is easily conductive after being coated and dried to form a film.

  On the other hand, a resin solution in which the resin is completely dissolved in a solvent is not preferable for use in forming the undercoat layer. This is because such a resin is difficult to become conductive after being coated and dried to form a film. An example of an unfavorable resin solution includes an aqueous carboxymethyl cellulose solution.

  The acid-modified latex may contain a rubber selected from the group consisting of NBR, SBR, acrylic rubber, fluororubber and IIR as a component. Specifically, the acid-modified latex may contain a synthetic rubber polymerized using an acidic monomer.

  The acidic monomer used as the raw material of the latex is not particularly limited as long as it has a pH lower than 7 at 20 ° C. when 1 g of the monomer is dissolved in water or mixed with water. A monomer is a preferred example. In particular, it is preferable to use an ethylenically unsaturated carboxylic acid monomer, an ethylenically unsaturated carboxylic acid ester monomer, and a monomer copolymerizable therewith if necessary. A method for producing acid-modified latex is described in paragraphs 0019 to 0024 of Patent Document 2, for example.

  Although there is no restriction | limiting in particular about the shape of a synthetic rubber particle, The particle diameter is 0.005-1000 micrometers normally, Preferably it is 0.01-100 micrometers, Most preferably, it is 0.05-20 micrometers. If the particle diameter is too large, it will be difficult to contact the conductive auxiliary material, and the internal resistance of the electrode will increase. If it is too small, the amount of the necessary binder becomes too large and the surface of the conductive auxiliary material is covered. The particle diameter referred to here is a value calculated as an average value obtained by measuring the longest diameter of 100 synthetic rubber particles in a latex state in a transmission electron micrograph.

  Since the latex used in the present invention is obtained using an acidic monomer such as an ethylenically unsaturated carboxylic acid monomer as the monomer as described above, the pH of the latex after polymerization is almost pH 4 or less. Therefore, it is necessary to neutralize the latex. The pH adjustment is pH 4.0 to 10.0, preferably pH 6.0 to 9.0 because it adversely affects the performance of the electronic component when the pH is lower than 4 and higher than pH 10.

  A commercially available acid-modified latex may be used. Examples of preferred commercial products include “BM-400B” manufactured by ZEON Corporation, “XSBR-0696” manufactured by JSR Corporation, “NA20” manufactured by Nippon A & L Co., Ltd., and “NA105S”.

  The undercoat layer may have a two-layer structure having a first undercoat layer and a second undercoat layer that are sequentially formed on the surface of the high-purity aluminum plain foil.

  The first undercoat layer is formed by applying and drying a synthetic rubber latex and, if necessary, a liquid (slurry) containing a dispersion medium on the surface of the aluminum plain foil. It is preferable not to contain a component that is not compatible with the synthetic rubber and inhibits the uniformity of the layer, such as a conductive additive. This is because the function of shielding the aluminum plain foil from the electrolyte is enhanced.

  The thickness of the first undercoat layer is 1 to 5 μm, preferably 1 to 2 μm in a dry state. When the thickness of the first undercoat layer is less than 1 μm, the barrier property of the electrolytic solution is insufficient, and when it exceeds 5 μm, the conductivity is insufficient.

  A preferable material for forming the second undercoat layer is a binder resin in which a conductive auxiliary agent is dispersed. The resin in which the conductive auxiliary agent is dispersed is generally a resin that is used when preparing a slurry of polarizable electrode material, as long as it is stable to an organic electrolyte and electrochemically stable. Examples include isoprene rubbers such as isoprene rubber (polyisoprene); butadiene rubbers such as butadiene rubber (cis-1,4-polybutadiene) and styrene-butadiene rubber (SBR); dienes such as nitrile rubber (NBR) and chloroprene rubber Olefin rubbers such as ethylene / propylene rubber, ethylene / propylene / diene rubber, and acrylic rubber; hydrin rubber; urethane rubber; fluorine rubber; A thickener such as carboxymethyl cellulose (CMC) may be used alone, or a mixture of CMC and the above synthetic rubber may be used.

  It is preferable that content (based on solid content) of the conductive auxiliary agent in the second undercoat layer is, for example, 50 to 99% by mass, 80 to 99% by mass, 90 to 99% by mass, and particularly 95 to 99% by mass. When the amount of the conductive auxiliary is less than 50% by mass, it is difficult to ensure conductivity, and when it exceeds 99% by mass, the coating property is deteriorated.

  The second undercoat layer is formed in the same manner as the undercoat layer. The thickness of the second undercoat layer is 1 to 5 μm, preferably 1 to 3 μm in a dry state. If the thickness of the second undercoat layer is less than 1 μm, it is difficult to ensure conductivity, and if it exceeds 5 μm, the volume of the effective polarizable electrode decreases.

  The collector electrode member on which the undercoat layer is formed is preferably heated after at least the second undercoat layer is formed, particularly when the undercoat layer has a two-layer structure. This is because the conductivity between the polarizable electrode is improved by heating. The step of heating the collector electrode member may be performed before the polarizable electrode is formed, or may be performed after the polarizable electrode is formed. Moreover, you may carry out simultaneously with the process of evaporating a dispersion medium.

  The heating temperature is generally 100 to 220 ° C, preferably 130 to 190 ° C. If the heating temperature is less than 100 ° C., the conductivity of the current collecting station member is not sufficiently improved, and if it exceeds 220 ° C., the deterioration of other electrode constituent materials proceeds. The heating time is generally 1 to 12 hours, preferably 4 to 8 hours. When the heating time is less than 1 hour, the conductivity is not improved sufficiently, and various properties are not improved even if the heat treatment is performed for more than 12 hours.

  The collector member thus obtained can be used for manufacturing an electrode member of an electric double layer capacitor. For example, a sheet-like electrode member is a mixture of a polarizable electrode material, a binding resin, and a conductive auxiliary agent, and dispersed in an appropriate dispersion medium to obtain a slurry of the electrode material, which is applied to the surface of the collector electrode member, It is formed by drying until the dispersion medium is completely evaporated.

As the electrode active material of the polarizable electrode, a carbonaceous material usually used for electric double layer capacitors such as activated carbon can be used. Activated carbon refers to amorphous carbon having a very large specific surface area because it has countless fine pores. In the present specification, amorphous carbon having a specific surface area of about 500 m ² / g or more is referred to as activated carbon.

The electrode active material may be non-porous carbon. Patent Document 3 describes nonporous carbon as an electrode active material used for an electric double layer capacitor. This carbon material has graphite-like microcrystals and a specific surface area of 300 m ² / g or less, which is relatively small. It is considered that an electrode containing non-porous carbon forms an electric double layer by inserting an electrolyte ion between fine graphite-like microcrystal layers with a solvent when a voltage is applied.

  The preferred non-porous carbon is, for example, a heat treatment of a carbon raw material at a high temperature of 800 to 1000 ° C. in an inert atmosphere, a further heat treatment in the presence of an alkali hydroxide powder and / or an alkali metal, and then removal of alkali content This is a carbon powder obtained. As the carbon raw material, graphitizable carbon generally called soft carbon can be used. The graphitizable carbon may be carbon that is graphitized by heating. For example, coke green powder, mesophase carbon, infusible vinyl chloride and the like correspond to graphitizable carbon.

  The method for producing non-porous carbon is different from the method for producing activated carbon in the type of carbon raw material and the heat treatment temperature. Activated carbon is produced by carbonizing non-graphitizable carbon, generally called hard carbon, at a low temperature of 300 to 700 ° C., and then activated with water vapor, chemicals, potassium, etc. to make it porous. .

Further, the electrode active material of the polarizable electrode may be graphite. Preferred graphite has a 002-plane crystal lattice constant C _{0 (002)} of 0.670 to 0.673 nm. Mean spacing d ₀₀₂ is 0.337nm or less, preferably 0.3352～0.3369Nm.

  In addition to carbon black, powdered graphite and the like can be used as the conductive auxiliary for the polarizable electrode, and PVDF, PE, PP and the like can be used in addition to PTFE as the binding resin. In this case, the blending ratio of non-porous carbon, conductive auxiliary agent (carbon black) and binder resin (PTFE) is generally about 10: 1: 0.5-10: 0.5-0.25. is there.

  The electrode member of the present invention can be preferably used for a non-aqueous electric double layer capacitor. This is because the non-aqueous electric double layer capacitor has a higher rated voltage than that of the water-based one. A polarizable electrode containing non-porous carbon or graphite as an electrode active material has a particularly high operating voltage and can increase the rated voltage. The non-aqueous electric double layer capacitor using the electrode member of the present invention may have a voltage with a rated voltage exceeding 3.2 V, for example, 3.3 V or more, 3.4 V or more, 3.5 V or more.

The non-aqueous electric double layer capacitor can be assembled by, for example, forming a positive electrode and a negative electrode by overlapping sheet-like electrode members with a separator interposed therebetween, and then impregnating the electrolyte. Examples of the electrolytic solution include non-aqueous solvents such as ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL) and sulfolane (SL), and acetonitrile (AC). For example, tetraethylmethyl ammonium (TEMAF) ₄ ) A non-aqueous solution in which a quaternary ammonium salt electrolyte such as spirobipyrrolidinium tetrafluoroborate (SBPBF ₄ ) is dissolved is used.

  The following examples further illustrate the present invention, but the present invention is not limited thereto. In the examples, “part” or “%” is based on weight unless otherwise specified.

Example
Production of non-porous carbon Remove quinoline insolubles from the soft pitch of coal, and put graphite precursor powder (made by Nippon Steel Co., Ltd.) carbonized using the refined raw material into an alumina crucible, which is muffled While circulating nitrogen in a furnace, the temperature was raised to 840 to 950 ° C. over 3 hours, followed by firing and natural cooling. Next, the fired product was mixed with 1.5 times the potassium hydroxide powder per weight ratio. Each was put in an alumina crucible and covered with an alumina lid to shut off the outside air.

  While this mixture was circulated with nitrogen in a muffle furnace, the temperature in the furnace was adjusted to 750 ° C., and the mixture was activated for 4 hours. The fired product was taken out, washed lightly with pure water, and then washed by applying ultrasonic waves. The time is 1 minute. The water was then separated using a Buchner funnel. The same washing operation was repeated until the pH of the washing water reached around 7. Then, the washed product was dried with a vacuum dryer.

  The dried carbon powder was put in a crucible, post-fired at 300 ° C. for 10 hours, then taken out and allowed to cool to room temperature.

This carbon powder was pulverized for 1 hour with 10 mmφ alumina balls using a ball mill (AV-1 manufactured by Fujiwara Seisakusho). When the particle size was measured with a Coulter counter, all of them became powdery with a center particle diameter of about 10 microns. It was 80 m < ² > / g when the specific surface area of the obtained powdery carbon was measured by BET method.

A high-purity aluminum plain foil (manufactured by Tokai Aluminum Co., Ltd.) having a capacitor cell production thickness of 20 μm and a purity of 99.85% was prepared. The rolling oil was removed from the surface of the foil by plasma treatment.

  7 g of acetylene black (“DENKA BLACK” manufactured by Denki Kagaku Kogyo Co., Ltd.) was dispersed in 6 g of acid-modified NBR latex (“NA20” manufactured by Nippon A & L Co., Ltd.), and water was added appropriately to prepare a slurry. And the said slurry was apply | coated to the surface of the high purity aluminum plain foil processed as mentioned above, and it was made to dry at 120 degreeC for 10 minute (s), and the 5-micrometer-thick undercoat layer was formed.

  Next, a slurry was prepared by adding SBR to a dispersion of powdered carbon in an aqueous carboxymethyl cellulose (CMC) solution to adjust the viscosity. The slurry was applied as a polarizable electrode layer on the undercoat layer. The obtained coated product laminate was pressed with a press machine to obtain a coated electrode having a thickness of 100 microns. This was heat-treated at 160 ° C. for 6 hours and dried to prepare a coated electrode member.

This coated electrode member was punched into a 20 mmφ disk and assembled into a three-electrode cell as shown in FIG. As the reference electrode, “# 1711” activated carbon manufactured by Kureha Chemical Co., Ltd. was dispersed in a CMC solution, the viscosity was adjusted with SBR, and a slurry was prepared to be a coated electrode. These cells were dried in a vacuum at 220 ° C. for 24 hours and cooled. An electrolyte solution was prepared by dissolving spirobipyrrolidinium tetrafluoroborate (SBPBF ₄ ) in propylene carbonate so as to be 2.0 mol%. And the obtained electrolyte solution was inject | poured into the cell, and the electrical double layer capacitor was produced.

Measurement of initial capacity and initial internal resistance After connecting the power system charge / discharge test device “CDT-RD20” to the assembled electric double layer capacitor and conducting electric field activation, the ambient temperature was kept at 25 ° C. and at 5 mA. Constant current and constant voltage charging was performed for 7200 seconds, and then constant current discharging was performed at 5 mA. The set voltage was 3.5 V, 3 cycles were performed, and the data for the third cycle was adopted.
The DC resistance (Ω) was calculated from the IR drop during constant current discharge. The electrostatic capacity (F / ml) was calculated from the discharge power.

The current value 7200 seconds after charging at the leakage current rated current was defined as the leakage current.

Measurement of capacity retention rate The rated voltage was continuously applied in a high temperature environment to measure how the cell capacitance changed. The ambient temperature was raised to 70 ° C., and charging / discharging under the above conditions was performed 100 cycles. Thereafter, the ambient temperature was returned to 25 ° C., charging and discharging were performed for 3 cycles, and the capacity and internal resistance were calculated. Table 1 shows the capacity retention rate (%) after 106 cycles of the electric double layer capacitor and the initial internal resistance (Ω) after 3 cycles.
The capacity maintenance rate was calculated from the following formula. The results are shown in Table 1.
Capacity maintenance rate (%) = C106 / C3 × 100

Withstand voltage test The same operation as the method for measuring the capacity retention rate was performed by changing the charging voltage by 0.1 V, and the voltage at which the capacity after 106 cycles was 80% of the initial capacity was defined as the withstand voltage.

Example 2
An electric double layer capacitor cell was produced and tested in the same manner as in Example 1 except that 6 g of acid-modified acrylonitrile butadiene rubber latex (“BM-400B” manufactured by Nippon Zeon Co., Ltd.) was used instead of acid-modified NBR latex. The test results are shown in Table 1.

Example 3
A slurry was prepared by appropriately adding water to 6 g of acid-modified NBR latex (“NA20” manufactured by Nippon A & L Co., Ltd.). And the said slurry was apply | coated to the surface of the high purity aluminum plain foil used in Example 1, and it dried at 120 degreeC for 10 minute (s), and formed the 1-micrometer-thick undercoat. Next, a slurry in which acetylene black was dispersed in an aqueous CMC solution in an amount of 97% by mass based on the solid content was applied to the surface of the first undercoat layer, dried at 120 ° C. for 10 minutes, and a thickness of 3 μm. A second undercoat layer was formed.

  Next, a slurry was prepared by adding SBR to a dispersion of powdered carbon in an aqueous carboxymethyl cellulose (CMC) solution to adjust the viscosity. The slurry was applied as a polarizable electrode layer on the second undercoat layer. The obtained coated product laminate was pressed with a press machine to obtain a coated electrode having a thickness of 100 microns. The finished electrode layer was heat-treated at 160 ° C. for 6 hours and dried to prepare a coated electrode member.

  An electric double layer capacitor cell was prepared and tested in the same manner as in Example 1 except that the obtained coated electrode member was used. The test results are shown in Table 1.

Example 4
An electric double layer capacitor cell was prepared and tested in the same manner as in Example 3 except that 12 g of acid-modified acrylonitrile butadiene rubber latex (“BM-400B” manufactured by Nippon Zeon Co., Ltd.) was used instead of acid-modified NBR latex. The test results are shown in Table 1.

Comparative Example 1
A high-purity aluminum etched foil (manufactured by JCC) having a thickness of 35 μm and a purity of 99.85% was prepared. The surface of the foil is roughened by etching using a method of applying an alternating current in an aqueous chloride solution.

  An electric double layer capacitor cell was produced and tested in the same manner as in Example 1 except that the high-purity aluminum etched foil thus treated was used. The test results are shown in Table 1.

Comparative Example 2
An electric double layer capacitor was prepared and tested in the same manner as in Example 1 except that no undercoat layer was formed on the surface of a high-purity aluminum plain foil having a purity of 99.85%. The test results are shown in Table 1.

[Table 1]

It is an assembly drawing which shows the structure of the electric double layer capacitor of an Example.

Explanation of symbols

1, 11 ... Insulating washer,
2 ... Top cover,
3 ... Spring,
4, 8 ... collector electrode,
5, 7 ... carbonaceous electrode,
6 ... separator,
9 ... Guide,
10, 13 ... O-ring,
12 ... the body,
14 ... Presser plate,
15 ... Reference electrode,
16 ... Bottom cover.

Claims (7)

A high-purity aluminum plain foil having an aluminum purity of 99.85% or more;
A collector electrode member for a non-aqueous electric double layer capacitor, comprising: an undercoat layer formed by applying and drying a slurry containing a conductive auxiliary agent and a latex of synthetic rubber on the surface of the aluminum plain foil.   The collector electrode member for a non-aqueous electric double layer capacitor according to claim 1, wherein the content of the conductive auxiliary agent in the undercoat layer is 40 to 80% by mass, and the content of the synthetic rubber is 20 to 60% by mass. A high-purity aluminum plain foil having an aluminum purity of 99.85% or more;
A first undercoat layer made of synthetic rubber, formed by applying and drying a slurry containing synthetic rubber latex on the surface of the aluminum plain foil;
A collector electrode member for a non-aqueous electric double layer capacitor having a second undercoat layer that is a layer comprising a conductive additive and a binder resin.   The collector electrode member for a non-aqueous electric double layer capacitor according to claim 3, wherein the content of the conductive auxiliary agent in the second undercoat layer is 50 to 99 mass%.   The collector member according to claim 3 or 4, which is heated at a temperature of 100 to 220 ° C for 1 to 12 hours in a state where at least the first undercoat layer and the second undercoat layer are formed.   The collector electrode member for a non-aqueous electric double layer capacitor according to any one of claims 1 to 5, wherein a rated voltage of the non-aqueous electric double layer capacitor exceeds 3.2V.   A non-aqueous electric double layer capacitor having a polarizable electrode layer containing non-porous carbon or graphite as an electrode active material on the surface of the collector electrode member for a non-aqueous electric double layer capacitor according to claim 1 Electrode member.

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