WO2024004740A1 - Electric double layer capacitor and method for producing same - Google Patents

Electric double layer capacitor and method for producing same Download PDF

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WO2024004740A1
WO2024004740A1 PCT/JP2023/022648 JP2023022648W WO2024004740A1 WO 2024004740 A1 WO2024004740 A1 WO 2024004740A1 JP 2023022648 W JP2023022648 W JP 2023022648W WO 2024004740 A1 WO2024004740 A1 WO 2024004740A1
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electrode
negative electrode
positive electrode
electric double
double layer
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PCT/JP2023/022648
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French (fr)
Japanese (ja)
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正輝 菅野
裕介 川崎
将之 萩谷
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日本ケミコン株式会社
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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
    • H01G11/14—Arrangements or processes for adjusting or protecting hybrid or EDL capacitors
    • H01G11/16—Arrangements or processes for adjusting or protecting hybrid or EDL capacitors against electric overloads, e.g. including fuses
    • 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
    • H01G11/24—Electrodes characterised by structural features of the materials making up or comprised in the electrodes, e.g. form, surface area or porosity; characterised by the structural features of powders or particles used therefor
    • 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
    • H01G11/54—Electrolytes
    • H01G11/58—Liquid electrolytes
    • H01G11/60—Liquid electrolytes characterised by the solvent
    • 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

Definitions

  • the present invention relates to a wound type electric double layer capacitor containing sulfolane and chain sulfone as a solvent and a manufacturing method.
  • An electric double layer capacitor consists of a device containing a pair of polarizable electrodes impregnated with an electrolyte and housed in a container, and utilizes the power storage effect of the electric double layer formed at the interface between the polarizable electrode and the electrolyte. ing.
  • This electric double layer capacitor has the advantage that the electrode active material is less likely to deteriorate due to repeated charging and discharging and has a long life.
  • an electric double layer capacitor uses activated carbon powder as a polarizable electrode material, a metal with a valve action such as aluminum as a current collector, and an aprotic electrolyte as an electrolyte.
  • a quaternary ammonium salt is mainly used as the electrolyte of the electrolytic solution.
  • a carbonate solvent such as polypropylene carbonate or a carboxylic acid ester such as ⁇ -butyrolactone is used as the solvent for the electrolytic solution (see, for example, Patent Document 1).
  • a carbonate solvent such as polypropylene carbonate or a carboxylic acid ester such as ⁇ -butyrolactone
  • electric double layer capacitors using carbonate-based solvents or ⁇ -butyrolactone tend to deteriorate in capacitance over time due to the recent demand for higher voltage resistance.
  • Electric double layer capacitors using sulfolane have improved withstand voltage compared to those using carbonate-based or ⁇ -butyrolactone as the electrolyte solvent.
  • Sulfolane is reported to have a freezing point of 28°C, and is mixed with dimethylsulfone in order to improve the low-temperature characteristics of electric double layer capacitors.
  • the present invention was proposed to solve the above problems.
  • the purpose is to provide an electric double layer capacitor that suppresses gas generation and a method for manufacturing the same.
  • an electric double layer capacitor is an electric double layer capacitor in which an element in which a positive electrode and a negative electrode are wound with a separator interposed therebetween is impregnated with an electrolytic solution.
  • the liquid contains sulfolane and chain sulfone as a solvent, and the capacitance ratio Cp:Cn between the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode is 1.3 or more:1.
  • the chain sulfone may be dimethylsulfone.
  • a capacitance ratio Cp:Cn between the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode may be 1.3:1 to 1.7:1.
  • the capacitance ratio Cp:Cn is 1.7 or less:1, it is also possible to suppress a decrease in capacitance.
  • the positive electrode and the negative electrode each have a current collector and a polarizable electrode layer on the current collector, and the thickness of the polarizable electrode layer of the positive electrode is equal to the thickness of the polarizable electrode layer of the negative electrode. It may be made to be 1.2 times or more and 1.5 times or less.
  • the capacitance ratio Cp:Cn of the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode is 1.3 or more. :Easy to fall within 1.
  • the capacitance ratio Cp:Cn is within this range, even if the withstand voltage of the electric double layer capacitor is 3.0V, the electrode potential of the positive electrode and the electrode potential of the negative electrode fall within the potential window of the mixed solvent of sulfolane and chain sulfone. It fits.
  • the capacity ratio expands beyond this range, the electrode potential of the negative electrode deviates from the potential window of the mixed solvent of sulfolane and chain sulfone.
  • the capacity ratio is narrower than this range, the electrode potential of the positive electrode deviates from the potential window of the mixed solvent of sulfolane and chain sulfone.
  • the electrode potential of the positive electrode (vs Ag/Ag+) is in the range of +0.58V to +0.78V
  • the electrode potential of the negative electrode (vs Ag/Ag+) is in the range of +0.58V to +0.78V. ) may be in the range of -2.42V to -2.19V.
  • the strip length of the negative electrode is longer than the positive electrode, and the element is wound such that the negative electrode is located at the innermost and outermost peripheries, and the negative electrode is wound more in the strip length direction than the positive electrode. It may be made to protrude at the beginning and end of winding.
  • the electrode potential of the positive electrode and the electrode potential of the negative electrode are shifted in the base direction.
  • this shift in the base direction becomes even larger. Therefore, the electrode potential of the positive electrode and the electrode potential of the negative electrode become more likely to fall within the potential window range of the mixed solvent of sulfolane and chain sulfone, and the mixed solvent of chain sulfone becomes electrochemically stable.
  • a positive electrode forming process is performed in which a positive electrode with an electrode potential (vs.Ag/Ag+) in the range of +0.58V to +0.78V is formed, and a positive electrode with an electrode potential (vs.Ag/Ag+) in the range of -2.
  • Another embodiment of the present invention is a method for manufacturing an electric double layer capacitor, which includes an electrolytic solution impregnation step of impregnating the electrolytic solution containing sulfone.
  • the electrode potential of the positive electrode and the electrode potential of the negative electrode tend to fall within the potential window of the mixed solvent of sulfolane and chain sulfone, thereby suppressing gas generation within the electric double layer capacitor.
  • Example 3 shows a cyclic voltammogram of a mixed solvent of sulfolane and chain sulfone and positive and negative electrode potentials in Example 3.
  • a cyclic voltammogram of a mixed solvent of sulfolane and chain sulfone and positive and negative electrode potentials in Example 4 are shown. It is a graph showing the amount of case swelling over time of electric double layer capacitors of each example and comparative example. It is a graph comparing the change over time of the capacitance change rate ⁇ Cap (%) of each electric double layer capacitor.
  • An electric double layer capacitor is a passive element that stores and discharges charges through capacitance by utilizing the power storage effect of an electric double layer formed at the interface between a polarizable electrode and an electrolyte.
  • the element of this electric double layer capacitor includes a positive electrode, a negative electrode, a separator, and an electrolyte, and has a wound shape.
  • the positive electrode and the negative electrode face each other with a separator in between.
  • the electrolytic solution fills the void of the capacitor element.
  • This element is housed in a case and sealed with a sealing body.
  • the case has a cylindrical shape with a bottom that houses the element, and is made of aluminum, for example.
  • the sealing body is attached to the opening of the case by crimping and seals the opening of the case.
  • Lead terminals are connected to the positive and negative electrodes.
  • An external terminal led out to the outside is attached to the sealing body.
  • the lead terminals connected to the positive and negative electrodes and the external terminals of the sealing body are electrically connected, so that the electric double layer capacitor can be mounted on a circuit.
  • the lead terminals connected to the positive electrode and the negative electrode are led out through the through hole of the sealing body.
  • the electrolytic solution contains sulfolane (hereinafter sometimes abbreviated as SLF) and chain sulfone (hereinafter sometimes abbreviated as CS) as a solvent.
  • SLF sulfolane
  • CS chain sulfone
  • the weight ratio of SLF:CS is in the range of 9:1 to 7:3. Within this range, it is possible to suppress deterioration of the performance of the electrical frost capacitor over time, for example, in a high breakdown voltage region of 3.0 V and a low temperature region of -20° C. to -30° C.
  • chain sulfone examples include dimethylsulfone, ethylmethylsulfone, butylisobutylsulfone, isopropylmethylsulfone, ethylisobutylsulfone, and ethylisopropylsulfone, and two or more of these may be mixed.
  • FIG. 1 shows a voltammogram obtained by cyclic voltammetry of a mixed solvent (hereinafter also simply referred to as mixed solvent) in which sulfolane and chain sulfone are mixed in a weight ratio of SLF:CS in the range of 9:1 to 7:3.
  • the cyclic voltammogram of a mixture of sulfolane and chain sulfone is measured as follows. That is, an activated carbon electrode with an area of 2 cm x 2 cm and a coating thickness of 51 ⁇ m is used as the working electrode, an activated carbon electrode with an area of 2 cm x 10 cm and a coating thickness of 50 ⁇ m as the counter electrode, and an Ag/Ag+reference electrode as the reference electrode.
  • a solution to which 2 mol of 5-azoniaspiro[4,4]nonane BF 4 is added per 1 L of the mixed solvent is used as a measurement solution.
  • Potential scanning is started from the immersion potential, and potential scanning is started from the immersion potential to 1.5 V on the positive side.
  • the potential scanning speed is 0.5 mV/s.
  • potential scanning is started from the immersion potential, and potential scanning is started from the immersion potential to -2.8V on the negative side.
  • the potential scanning speed is 0.5 mV/s.
  • a separator is sandwiched between a positive electrode and a negative electrode having an area of 2 cm ⁇ 2 cm, and an element is produced in which the positive electrode and the negative electrode are sandwiched between glass plates from the outside.
  • the device is immersed in a solution containing 2 mol of 5-azoniaspiro[4,4]nonane BF 4 per 1 L of mixed solvent.
  • a reference electrode (Ag/Ag+) is also placed in the solution.
  • this electric double layer capacitor is charged to 3.0V with a current of 5A, for example, and held for 4 hours.
  • the potentials of the positive and negative electrodes with respect to the reference electrode are set as polarization potentials.
  • the potential window of the mixed solvent ranges from -2.42V to +0.78V.
  • the dotted lines indicate the lower limit of the potential window on the negative side and the upper limit of the potential window on the positive side.
  • the electrolyte of the electrolytic solution may be any electrolyte as long as it can generate quaternary ammonium ions, and examples thereof include one or more selected from various quaternary ammonium salts.
  • Cations include tetramethylammonium, ethyltrimethylammonium, tetraethylammonium, triethylmethylammonium, diethyldimethylammonium, methylethylpyrrolidinium, spirobipyrrolidinium, etc.
  • anions include BF 4 - , PF 6 - , ClO 4 ⁇ , AsF 6 ⁇ , SbF 6 ⁇ , AlCl 4 ⁇ , or RfSO 3 ⁇ , (RfSO 2 ) 2 N ⁇ , RfCO 2 ⁇ (Rf is a fluoroalkyl group having 1 to 8 carbon atoms), etc. Can be done.
  • quaternary ammonium salts include tetramethylammonium BF 4 , ethyltrimethylammonium BF 4 , diethyldimethylammonium BF 4 , triethylmethylammonium BF 4 , tetraethylammonium BF 4 , spirobipyrrolidinium BF 4 , methyl Ethylpyrrolidinium BF 4 , Tetramethylammonium PF 6 , Ethyltrimethylammonium PF 6 , Diethyldimethylammonium PF 6 , Triethylmethylammonium PF 6 , Tetraethylammonium PF 6 , Spirobipyrrolidinium PF 6 , Methylethylpyrrolidinium PF 6.
  • phosphoric acids and their derivatives phosphoric acid, phosphorous acid, phosphoric acid esters, phosphonic acids, etc.
  • boric acids and their derivatives boric acids and their derivatives (boric acid, boric acid oxide, boric acid esters, boron and complexes with compounds having a hydroxyl group and/or carboxyl group, etc.), nitrates (lithium nitrate, etc.), nitro compounds (nitrobenzoic acid, nitrophenol, nitrophenethol, nitroacetophenone, aromatic nitro compounds, etc.).
  • the positive electrode and the negative electrode are mainly composed of a current collector and a polarizable electrode layer.
  • the current collector is a metal such as aluminum foil, platinum, gold, nickel, titanium, and steel.
  • the shape of the current collector may be any shape such as a film, a foil, a plate, a net, an expanded metal, or a cylinder. Further, the surface of the current collector may be formed with an uneven surface by etching or the like, or may be a plain surface.
  • the polarizable electrode layer mainly contains activated carbon.
  • Activated carbon is made from natural plant tissues such as coconut shells, synthetic resins such as phenol, fossil fuels such as coal, coke, and pitch, and is processed through activation treatments such as steam activation, alkali activation, zinc chloride activation, or electric field activation. In addition, it is sufficient that the opening treatment is performed.
  • the capacitance of the positive electrode is Cp.
  • the capacitance of the negative electrode is Cn.
  • the polarizable electrode layer is adjusted so that the capacitance ratio Cp:Cn between the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode is 1.3 or more:1.
  • the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode are measured as follows. That is, a test piece of a specified area is cut out, immersed in a capacitance measurement liquid in a glass measurement tank using a platinum plate as a counter electrode, and measured using a capacitance meter.
  • the specified area is 1 cm2
  • the capacitance measurement liquid is an ammonium pentaborate aqueous solution at 30°C
  • the capacitance meter is a potentiostat
  • a frequency response analyzer is a frequency response analyzer
  • an electrochemical impedance analyzer is an LCR meter, etc.
  • the measurement conditions are as follows:
  • the DC bias voltage is 1.5V
  • the AC amplitude is 1V.
  • the electrode potential of the positive electrode vs. Ag/Ag+QRE
  • the electrode potential of the negative electrode vs. Ag/Ag+QRE
  • the electrode potential of the negative electrode vs. Ag/Ag+QRE
  • the capacitance Cp of the positive electrode is 1.7 times or less than the capacitance Cn of the negative electrode, and within this range, a decrease in the capacitance of the electric double layer capacitor can also be suppressed.
  • the positive electrode potential and negative electrode potential are measured as follows. That is, a separator is sandwiched between a positive electrode and a negative electrode having an area of 2 cm x 2 cm, and an element is produced in which the positive electrode and the negative electrode are sandwiched between glass plates from the outside.
  • the device is immersed in a solution containing 2 mol of 5-azoniaspiro[4,4]nonane BF 4 per 1 L of mixed solvent.
  • a reference electrode (Ag/Ag+) is also placed in the solution. Then, this electric double layer capacitor is charged to 3.0V with a current of 5A, for example, and held for 4 hours. After holding for 4 hours, the potentials of the positive and negative electrodes with respect to the reference electrode are set as polarization potentials.
  • the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode can also be adjusted by the thickness of each polarizable electrode layer. That is, in order to set the capacitance ratio Cp:Cn between the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode to 1.3:1 to 1.7:1, the thickness of the polarizable electrode layer of the positive electrode should be The thickness is preferably 1.2 or more and 1.5 or less times the thickness of the polarizable electrode layer. In other words, the thickness ratio Tp:Tn of the thickness Tp of the polarizable electrode layer of the positive electrode and the thickness Tn of the polarizable electrode layer of the negative electrode is preferably 1.2:1 to 1.5:1. Furthermore, since the capacitance is proportional to the foil area, the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode can also be adjusted by adjusting the length of each foil.
  • the polarizable electrode layer may be formed by, for example, applying a slurry of activated carbon and a binder onto the current collector using a doctor blade method or the like and drying it.
  • a mixture of the carbon material and the binder may be formed into a sheet shape, and the sheet may be pressure-bonded to the current collector.
  • the binder include rubbers such as fluorine rubber, diene rubber, and styrene rubber, fluorine-containing polymers such as polytetrafluoroethylene and polyvinylidene fluoride, celluloses such as carboxymethyl cellulose and nitrocellulose, and other materials such as polyolefin resins and polyimides.
  • Examples include resins, acrylic resins, nitrile resins, polyester resins, phenol resins, polyvinyl acetate resins, polyvinyl alcohol resins, and epoxy resins. These binders may be used alone or in combination of two or more.
  • the polarizable electrode layer may contain a conductive additive.
  • conductive additives include carbon black such as Ketjen black, acetylene black, and channel black, carbon nanohorn, amorphous carbon, natural graphite, artificial graphite, graphitized Ketjen black, mesoporous carbon, carbon nanotubes, and carbon nanofibers.
  • Carbon nanotubes can be single-walled carbon nanotubes (SWCNTs), which have a single layer of graphene sheets, or multi-walled carbon nanotubes (MWCNTs), which have two or more layers of graphene sheets rolled coaxially and have multiple tube walls, or they can be mixed. may have been done.
  • phosphorus that suppresses hydration and oxidation of the current collector may be attached to the surface of the current collector.
  • the current collector is immersed in an aqueous phosphoric acid solution or an aqueous phosphate solution.
  • a carbon coat layer containing a conductive agent such as graphite may be provided between the current collector and the polarizable electrode layer.
  • a carbon coat layer can be formed by applying a slurry containing a conductive agent such as graphite, a binder, etc. to the surface of a current collector and drying the slurry.
  • Such a positive electrode and a negative electrode have a long band shape and are spirally wound with a separator interposed therebetween.
  • the direction along the spiral is called the band length direction, and generally, the positive and negative electrodes are wound along the longitudinal direction, and this longitudinal direction is the band length direction.
  • FIG. 2 is a schematic diagram showing a method of winding a positive electrode and a negative electrode, with the dotted line representing the positive electrode and the solid line representing the negative electrode.
  • the negative electrode is longer in the band length direction than the positive electrode, and the negative electrode is the innermost circumference and the outermost circumference
  • Negative electrode non-facing portions that do not face the positive electrode are formed at the beginning and end of winding the negative electrode. That is, the element is formed with the negative electrode as the first winding start side and the second winding end side.
  • the negative electrode foils are positioned at the innermost and outermost peripheries.
  • the electrode potential of the positive electrode and the electrode potential of the negative electrode are shifted to the base direction.
  • the shift in direction becomes even larger. Therefore, the electrode potential of the negative electrode and the electrode potential of the positive electrode are more likely to fall within the potential window of the mixed solvent, and the chain sulfone becomes electrochemically stable.
  • Such an electric double layer capacitor is manufactured through a positive electrode forming process, a negative electrode forming process, an element forming process, and an electrolyte impregnation process.
  • a polarizable electrode layer is formed on the current collector, and a positive electrode with an electrode potential (vs. Ag/Ag+) in the range of +0.58V to +0.78V is formed by adjusting the polarizable electrode layer. do.
  • a polarizable electrode layer is formed on the current collector, and by adjusting the polarizable electrode layer, the electrode potential (vs. Ag/Ag+) is in the range of -2.42V to -2.19V. form the negative electrode.
  • a positive electrode and a negative electrode are spirally wound with a separator interposed therebetween.
  • the negative electrode foil is positioned at the innermost and outermost peripheries.
  • Electric double layer capacitors of Examples 1 to 3 and Comparative Example 1 with a withstand voltage of 3.0 V were manufactured as follows. That is, a slurry was obtained by mixing steam-activated carbon, carbon black, carboxymethyl cellulose as a dispersant, SBR emulsion as a binder, and pure water.
  • a current collector foil was prepared by applying a paint containing graphite to the surface of the aluminum foil to form a carbon coat layer on both sides of the aluminum foil. A similarly prepared slurry was applied to both sides of the prepared current collector foil and dried to produce a positive electrode and a negative electrode having the same length in the band width direction.
  • the center lines of the positive and negative electrodes extending in the band length direction were aligned and overlapped with a rayon separator interposed therebetween to form a wound type element.
  • the negative electrode was placed at the beginning of the first winding and at the end of the second winding.
  • the negative electrode was rolled in first, and the layer of positive electrode, separator, and negative electrode was wound so that the negative electrode was on the inner circumferential side and the positive electrode on the outer circumferential side, and at the outermost circumference, the negative electrode was wound last beyond the end of the positive electrode. . Therefore, negative electrode non-facing portions that do not face the positive electrode are formed at the beginning and end of winding the negative electrode.
  • the amount of activated carbon in the portion not facing the negative electrode was the same in Examples 1 to 3 and Comparative Example 1, and was 6 wt % based on the total amount of activated carbon coated on the negative electrode.
  • This element was impregnated with an electrolyte.
  • 2.0M 5-azoniaspiro[4,4]nonane BF 4 was used as the solute in the electrolyte.
  • 2.0M represents the number of moles of electrolyte (mol/L) with respect to 1L of electrolyte solution.
  • the element was impregnated with this electrolytic solution, and the element impregnated with the electrolytic solution was placed in a case of ⁇ 18 ⁇ 50 L and sealed with a sealing body.
  • the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1 differ in the coating thickness of the polarizable electrode layer and the lengths of the positive electrode and negative electrode.
  • the capacitance ratio Cp:Cn between the capacitance Cp and the capacitance Cn of the negative electrode is different.
  • the capacitance ratio Cp:Cn is 1.2:1, so when calculating the capacitance ratio, a coefficient is added to the capacitance Cp on the positive electrode side. Multiplied by 1.2. The reason for this multiplication is that the difference in ion size between the cation component and the anion component on the positive electrode side and the magnitude of the reaction current on the positive electrode side are taken into consideration.
  • the electrode potentials V (vs. Ag/Ag+) of the positive and negative electrodes of the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1 were measured.
  • the method and conditions for measuring the electrode potential V are as follows. That is, the elements of Examples 1 to 4 and Comparative Example 1 were immersed in an electrolytic solution. The element was also impregnated with the electrolyte. A reference electrode (Ag/Ag+) was placed at the outermost periphery of the element. Then, it was charged to 3.0V at 5A and held for 4 hours. The potential of the positive and negative electrodes with respect to the reference electrode after holding for 4 hours was defined as the polarization potential.
  • each electrode potential was written on the cyclic voltammogram of the mixed solvent of sulfolane and chain sulfone.
  • the results are shown in FIGS. 3 to 7.
  • 3 shows the positive and negative electrode potentials of Comparative Example 1
  • FIG. 4 shows the positive and negative electrode potentials of Example 1
  • FIG. 5 shows the positive and negative electrode potentials of Example 2
  • FIG. 6 shows the positive and negative electrode potentials of Example 3.
  • 7 shows the positive and negative electrode potentials of Example 4.
  • the dotted line is the lower limit value on the negative side and the upper limit value on the positive side of the potential window
  • the solid line is the electrode potential of the positive electrode and the electrode potential of the negative electrode.
  • Example 1 to 3 in which the capacitance Cp:Cn of the positive electrode and negative electrode is in the range of 1.3 or more:1, the electrode potential of the positive electrode and the electrode potential of the negative electrode are within the potential window of the mixed solvent of sulfolane and chain sulfone. It is within the range.
  • Example 4 where the capacity Cp:Cn of the positive electrode and negative electrode is in the range of 1.91:1, the electrode potential of the positive electrode falls within the range of the potential window of the mixed solvent of sulfolane and chain sulfone, and the electrode potential of the negative electrode falls within the range of the potential window of the mixed solvent of sulfolane and chain sulfone. It is close to the lower limit of the electrode window.
  • Table 3 shows the results of case swelling amounts of the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1. (Table 3)
  • FIG. 8 is a graph showing the amount of swelling of the case after being left for 3000 hours, where the horizontal axis is the ratio of the positive electrode capacitance Cp to the negative electrode capacitance Cn, and the vertical axis is the swelling amount of the case.
  • the capacity Cp of the positive electrode is 1.3 times or more the capacity Cn of the negative electrode, and the electrode potential of the positive electrode is within the potential window of the mixed solvent of sulfolane and chain sulfone.
  • the electrode potential of the negative electrode is within the electrode window or is close to the lower limit.
  • the capacitances of the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1 were measured according to a constant current discharge method. That is, a constant voltage of 3.0 V was applied in a temperature environment of 20° C., and the electric double layer capacitor was charged over 20 minutes. Immediately after charging was completed, the battery was discharged at a constant current I, and the time T required for the voltage to drop from the measurement start voltage excluding IR drop to the measurement end voltage of 1.35V was measured. Then, the capacity (F) was calculated from the product of the constant current I and the required time T and the difference (V) between the measurement start voltage and the measurement end voltage. The measurement was performed four times, and the average value was used.
  • Table 4 shows changes over time in the capacitance change rate ⁇ Cap (%) of the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1. (Table 4)
  • FIG. 9 shows changes over time in the capacitance change rate ⁇ Cap (%) of the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1.
  • FIG. 9 is a graph comparing the changes over time in the capacitance change rate ⁇ Cap (%) of each electric double layer capacitor.
  • the graph plotted with x marks indicates Comparative Example 1
  • the graph plotted with white square marks indicates Example 1
  • the graph plotted with asterisks indicates Example 2
  • the graph plotted with filled squares indicates Example 2.
  • the graph plotted with marks indicates Example 3, and the graph plotted with triangle marks indicates Example 4.
  • the electrode potential of the positive electrode falls within the range of the potential window of the mixed solvent of sulfolane and chain sulfone, It was confirmed that the electrode potential of the negative electrode was within the electrode window or close to the lower limit. Based on the gas generation amount measurement test and capacitance measurement test, the positive electrode and electrode potentials are within the potential window of this mixed solvent, so that even if the withstand voltage is 3.0V or more, the gas inside the electric double layer capacitor is It was confirmed that the amount generated was suppressed and the decrease in capacitance over time was also suppressed.

Abstract

The present invention provides: an electric double layer capacitor which is suppressed in gas generation; and a method for producing this electric double layer capacitor. This electric double layer capacitor is obtained by impregnating an element, which is obtained by winding a positive electrode and a negative electrode with a separator being interposed therebetween, with an electrolyte solution that contains sulfolane and a chain sulfone as solvents. The ratio Cp:Cn of the electrostatic capacitance Cp of the positive electrode to the electrostatic capacitance Cn of the negative electrode is set to (1.3 or more):1. The positive electrode is formed such that the electrode potential (vs Ag/Ag+) is within or in the vicinity of the range of +0.58 V to +0.78 V; and the negative electrode is formed such that the electrode potential (vs Ag/Ag+) is within the range of -2.42 V to -2.19 V. According to the present invention, an element is formed by winding a positive electrode and a negative electrode with a separator being interposed therebetween; and the element is impregnated with an electrolyte solution that contains sulfolane and a chain sulfone as solvents.

Description

電気二重層キャパシタ及びその製造方法Electric double layer capacitor and its manufacturing method
　本発明は、スルホランと鎖状スルホンを溶媒として含む巻回型の電気二重層キャパシタ及び製造方法に関する。 The present invention relates to a wound type electric double layer capacitor containing sulfolane and chain sulfone as a solvent and a manufacturing method.
　電気二重層キャパシタは、一対の分極性電極を電解液に含浸させた素子を容器に収容して成り、分極性電極と電解液との境界面に形成される電気二重層の蓄電作用を利用している。この電気二重層キャパシタは、繰り返し充放電による電極活物質の劣化が少なく長寿命であるという利点を有する。 An electric double layer capacitor consists of a device containing a pair of polarizable electrodes impregnated with an electrolyte and housed in a container, and utilizes the power storage effect of the electric double layer formed at the interface between the polarizable electrode and the electrolyte. ing. This electric double layer capacitor has the advantage that the electrode active material is less likely to deteriorate due to repeated charging and discharging and has a long life.
　電気二重層キャパシタは、代表的には、分極性電極材料に活性炭粉末が用いられ、集電体にアルミニウム等の弁作用を有する金属が用いられ、非プロトン系電解液が電解液として用いられる。電解液の電解質は、第４級アンモニウム塩が主に用いられる。 Typically, an electric double layer capacitor uses activated carbon powder as a polarizable electrode material, a metal with a valve action such as aluminum as a current collector, and an aprotic electrolyte as an electrolyte. As the electrolyte of the electrolytic solution, a quaternary ammonium salt is mainly used.
　電解液の溶媒は、代表的には、ポリプロピレンカーボネート等のカーボネート系溶媒や、γーブチロラクトン等のカルボン酸エステルが用いられる（例えば特許文献１参照）。しかしながら、カーボネート系溶媒やγ－ブチロラクトンを用いた電気二重層キャパシタは、近年の高耐電圧化の要請に伴い、経時的な静電容量の悪化が大きくなっていく傾向がある。 Typically, a carbonate solvent such as polypropylene carbonate or a carboxylic acid ester such as γ-butyrolactone is used as the solvent for the electrolytic solution (see, for example, Patent Document 1). However, electric double layer capacitors using carbonate-based solvents or γ-butyrolactone tend to deteriorate in capacitance over time due to the recent demand for higher voltage resistance.
　そこで、スルホランとジメチルスルホンの混合溶媒を電解液に用いた電気二重層キャパシタが提案されている（例えば特許文献２参照）。スルホランを用いた電気二重層キャパシタは、カーボネート系やγ－ブチロラクトンを電解液の溶媒に用いた場合と比べて耐電圧が改善される。スルホランは、凝固点が２８℃であると報告されており、電気二重層キャパシタの低温特性を向上させるために、ジメチルスルホンが混合されるものである。 Therefore, an electric double layer capacitor using a mixed solvent of sulfolane and dimethylsulfone as an electrolyte has been proposed (see, for example, Patent Document 2). Electric double layer capacitors using sulfolane have improved withstand voltage compared to those using carbonate-based or γ-butyrolactone as the electrolyte solvent. Sulfolane is reported to have a freezing point of 28°C, and is mixed with dimethylsulfone in order to improve the low-temperature characteristics of electric double layer capacitors.
特開２００１－２１７１５０号公報Japanese Patent Application Publication No. 2001-217150 特開２０１３－１７５６１９号公報Japanese Patent Application Publication No. 2013-175619
　しかしながら、ジメチルスルホン等の鎖状スルホンを混合することで低温特性を向上させた場合、電気二重層キャパシタの正極側が経時的に酸性側にシフトし、負極側が経時的にアルカリ側にシフトしたとき、鎖状スルホンが電気化学的に酸化分解してしまう。そして、この鎖状スルホンの分解によって水素や一酸化炭素等のガスが発生してしまう。これらガスは、電気二重層キャパシタの内圧を上昇させてしまう虞がある。 However, when the low temperature characteristics are improved by mixing a chain sulfone such as dimethyl sulfone, when the positive electrode side of the electric double layer capacitor shifts to the acidic side over time, and the negative electrode side shifts to the alkaline side over time, The chain sulfone is electrochemically oxidized and decomposed. Then, gases such as hydrogen and carbon monoxide are generated by decomposition of this chain sulfone. These gases may increase the internal pressure of the electric double layer capacitor.
　本発明は、上記課題を解決するために提案されたものである。その目的は、ガス発生を抑制した電気二重層キャパシタ及びその製造方法を提供することにある。 The present invention was proposed to solve the above problems. The purpose is to provide an electric double layer capacitor that suppresses gas generation and a method for manufacturing the same.
　発明者らの鋭意研究の結果、正極の静電容量Ｃｐと負極の静電容量Ｃｎの容量比Ｃｐ：Ｃｎを１．３以上：１とすると、スルホランに鎖状スルホン混合させた溶媒を電気二重層キャパシタの電解液に用いても、水素ガスや一酸化炭素ガスの発生が抑制されるとの知見が得られた。 As a result of intensive research by the inventors, we found that when the capacitance ratio Cp:Cn of the positive electrode capacitance Cp and the negative electrode capacitance Cn is set to 1.3 or more:1, a solvent containing a chain sulfone mixed with sulfolane can be It has been found that the generation of hydrogen gas and carbon monoxide gas can be suppressed even when used in the electrolyte solution of multilayer capacitors.
　このメカニズムは推測であり、このメカニズムに限定されるものではないが、正極の静電容量Ｃｐと負極の静電容量Ｃｎの容量比Ｃｐ：Ｃｎを１．３以上：１の範囲とすると、正極の電極電位及び負極の電極電位がスルホランと鎖状スルホンの混合溶媒の電位窓の範囲に収まる。そのため、鎖状スルホンが電気化学的に安定し、電気化学的酸化分解が生じ難くなる。従って、スルホランに鎖状スルホンを混合させた溶媒を電気二重層キャパシタの電解液に用いても、水素ガスや一酸化炭素ガスの発生が抑制される。 Although this mechanism is speculation and is not limited to this mechanism, if the capacitance ratio Cp:Cn of the positive electrode capacitance Cp and the negative electrode capacitance Cn is in the range of 1.3 or more:1, the positive electrode The electrode potential of and the electrode potential of the negative electrode fall within the potential window of the mixed solvent of sulfolane and chain sulfone. Therefore, the chain sulfone becomes electrochemically stable and electrochemical oxidative decomposition is less likely to occur. Therefore, even if a solvent in which sulfolane and chain sulfone are mixed is used in the electrolyte solution of an electric double layer capacitor, the generation of hydrogen gas and carbon monoxide gas is suppressed.
　そこで、上記の課題を解決すべく、実施形態の電気二重層キャパシタは、正極と負極とをセパレータを介して巻回した素子に電解液を含浸させて成る電気二重層キャパシタであって、前記電解液は、溶媒としてスルホランと鎖状スルホンを含有し、前記正極の静電容量Ｃｐと前記負極の静電容量Ｃｎの容量比Ｃｐ：Ｃｎは、１．３以上：１とする。 Therefore, in order to solve the above problems, an electric double layer capacitor according to an embodiment is an electric double layer capacitor in which an element in which a positive electrode and a negative electrode are wound with a separator interposed therebetween is impregnated with an electrolytic solution. The liquid contains sulfolane and chain sulfone as a solvent, and the capacitance ratio Cp:Cn between the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode is 1.3 or more:1.
　鎖状スルホンは、ジメチルスルホンであってもよい。 The chain sulfone may be dimethylsulfone.
　前記正極の静電容量Ｃｐと前記負極の静電容量Ｃｎの容量比Ｃｐ：Ｃｎは、１．３：１～１．７：１であるようにしてもよい。容量比Ｃｐ：Ｃｎが１．７以下：１であると、静電容量の低下を抑制することもできる。 A capacitance ratio Cp:Cn between the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode may be 1.3:1 to 1.7:1. When the capacitance ratio Cp:Cn is 1.7 or less:1, it is also possible to suppress a decrease in capacitance.
　前記正極と前記負極は、各々が、集電体と当該集電体上の分極性電極層とを有し、前記正極の分極性電極層の厚みは、前記負極の分極性電極層の厚みに対し１．２倍以上１．５倍以下であるようにしてもよい。 The positive electrode and the negative electrode each have a current collector and a polarizable electrode layer on the current collector, and the thickness of the polarizable electrode layer of the positive electrode is equal to the thickness of the polarizable electrode layer of the negative electrode. It may be made to be 1.2 times or more and 1.5 times or less.
　正極の分極性電極層の厚みと負極の分極性電極層の厚みの厚み比をこの範囲にすると、正極の静電容量Ｃｐと負極の静電容量Ｃｎの容量比Ｃｐ：Ｃｎが１．３以上：１に収まり易い。 When the thickness ratio between the thickness of the polarizable electrode layer of the positive electrode and the thickness of the polarizable electrode layer of the negative electrode is within this range, the capacitance ratio Cp:Cn of the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode is 1.3 or more. :Easy to fall within 1.
　ここで、容量比Ｃｐ：Ｃｎをこの範囲にすると、電気二重層キャパシタの耐電圧を３．０Ｖとしても、正極の電極電位及び負極の電極電位がスルホランと鎖状スルホンの混合溶媒の電位窓に収まる。容量比がこの範囲を超えて拡がると、負極の電極電位がスルホランと鎖状スルホンの混合溶媒の電位窓から逸脱する。容量比がこの範囲よりも狭まると、正極の電極電位がスルホランと鎖状スルホンの混合溶媒の電位窓から逸脱する。 Here, when the capacitance ratio Cp:Cn is within this range, even if the withstand voltage of the electric double layer capacitor is 3.0V, the electrode potential of the positive electrode and the electrode potential of the negative electrode fall within the potential window of the mixed solvent of sulfolane and chain sulfone. It fits. When the capacity ratio expands beyond this range, the electrode potential of the negative electrode deviates from the potential window of the mixed solvent of sulfolane and chain sulfone. When the capacity ratio is narrower than this range, the electrode potential of the positive electrode deviates from the potential window of the mixed solvent of sulfolane and chain sulfone.
　即ち、電気二重層キャパシタの耐電圧を３．０Ｖとしても、前記正極の電極電位（ｖｓ　Ａｇ／Ａｇ＋）が＋０．５８Ｖ～＋０．７８Ｖの範囲であり、前記負極の電極電位（ｖｓ　Ａｇ／Ａｇ＋）が－２．４２Ｖ～－２．１９Ｖの範囲とすればよい。 That is, even if the withstand voltage of the electric double layer capacitor is 3.0V, the electrode potential of the positive electrode (vs Ag/Ag+) is in the range of +0.58V to +0.78V, and the electrode potential of the negative electrode (vs Ag/Ag+) is in the range of +0.58V to +0.78V. ) may be in the range of -2.42V to -2.19V.
　前記負極の帯長さは、前記正極よりも長く、前記素子は、前記負極が最内周及び最外周に位置するように巻回され、前記負極は、前記正極よりも帯長さ方向において巻き始め及び巻き終わりではみ出すようにしてもよい。 The strip length of the negative electrode is longer than the positive electrode, and the element is wound such that the negative electrode is located at the innermost and outermost peripheries, and the negative electrode is wound more in the strip length direction than the positive electrode. It may be made to protrude at the beginning and end of winding.
　負極の静電容量Ｃｐを負極の静電容量Ｃｎよりも大きくすることで、正極の電極電位及び負極の電極電位は卑方向へシフトする。負極に非対向部分を生じさせることで、この卑方向へのシフトは更に大きくなる。従って、正極の電極電位及び負極の電極電位がスルホランと鎖状スルホンの混合溶媒の電位窓の範囲に益々収まり易くなり、鎖状スルホンの混合溶媒が電気化学的に安定する。 By making the capacitance Cp of the negative electrode larger than the capacitance Cn of the negative electrode, the electrode potential of the positive electrode and the electrode potential of the negative electrode are shifted in the base direction. By creating a non-opposed portion in the negative electrode, this shift in the base direction becomes even larger. Therefore, the electrode potential of the positive electrode and the electrode potential of the negative electrode become more likely to fall within the potential window range of the mixed solvent of sulfolane and chain sulfone, and the mixed solvent of chain sulfone becomes electrochemically stable.
　上記の課題を解決すべく、電極電位（ｖｓ．　Ａｇ／Ａｇ＋）が＋０．５８Ｖ～＋０．７８Ｖの範囲の正極を形成する正極形成工程と、電極電位（ｖｓ．　Ａｇ／Ａｇ＋）が－２．４２Ｖ～－２．１９Ｖの範囲の負極を形成する負極形成工程と、前記正極と前記負極とをセパレータを介して巻回して素子を形成する素子形成工程と、前記素子に溶媒としてスルホランと鎖状スルホンを含有する電解液を含浸させる電解液含浸工程と、を含む、電気二重層キャパシタの製造方法も本発明の一態様である。 In order to solve the above problems, a positive electrode forming process is performed in which a positive electrode with an electrode potential (vs.Ag/Ag+) in the range of +0.58V to +0.78V is formed, and a positive electrode with an electrode potential (vs.Ag/Ag+) in the range of -2. a negative electrode forming step of forming a negative electrode in the range of 42 V to -2.19 V; an element forming step of winding the positive electrode and the negative electrode with a separator in between to form an element; Another embodiment of the present invention is a method for manufacturing an electric double layer capacitor, which includes an electrolytic solution impregnation step of impregnating the electrolytic solution containing sulfone.
　本発明によれば、正極の電極電位及び負極の電極電位がスルホランと鎖状スルホンの混合溶媒の電位窓の範囲に収まり易くなり、電気二重層キャパシタ内のガス発生を抑制する。 According to the present invention, the electrode potential of the positive electrode and the electrode potential of the negative electrode tend to fall within the potential window of the mixed solvent of sulfolane and chain sulfone, thereby suppressing gas generation within the electric double layer capacitor.
スルホランと鎖状スルホンの混合溶媒のサイクリックボルタモグラムを示すグラフである。It is a graph showing a cyclic voltammogram of a mixed solvent of sulfolane and chain sulfone. 正極及び負極の巻回方法を示す図である。It is a figure which shows the winding method of a positive electrode and a negative electrode. スルホランと鎖状スルホンの混合溶媒のサイクリックボルタモグラムと比較例１の正負の電極電位を示す。A cyclic voltammogram of a mixed solvent of sulfolane and chain sulfone and positive and negative electrode potentials of Comparative Example 1 are shown. スルホランと鎖状スルホンの混合溶媒のサイクリックボルタモグラムと実施例１の正負の電極電位を示す。1 shows a cyclic voltammogram of a mixed solvent of sulfolane and chain sulfone and positive and negative electrode potentials of Example 1. スルホランと鎖状スルホンの混合溶媒のサイクリックボルタモグラムと実施例２の正負の電極電位を示す。3 shows a cyclic voltammogram of a mixed solvent of sulfolane and chain sulfone and positive and negative electrode potentials in Example 2. スルホランと鎖状スルホンの混合溶媒のサイクリックボルタモグラムと実施例３の正負の電極電位を示す。3 shows a cyclic voltammogram of a mixed solvent of sulfolane and chain sulfone and positive and negative electrode potentials in Example 3. スルホランと鎖状スルホンの混合溶媒のサイクリックボルタモグラムと実施例４の正負の電極電位を示す。A cyclic voltammogram of a mixed solvent of sulfolane and chain sulfone and positive and negative electrode potentials in Example 4 are shown. 各実施例及び比較例の電気二重層キャパシタの経時的なケース膨れ量を示すグラフである。It is a graph showing the amount of case swelling over time of electric double layer capacitors of each example and comparative example. 各電気二重層キャパシタの容量変化率ΔＣａｐ（％）の経時変化を比較したグラフである。It is a graph comparing the change over time of the capacitance change rate ΔCap (%) of each electric double layer capacitor.
　以下、本発明の実施形態に係る電気二重層キャパシタ及びその製造方法について説明する。なお、本発明は、以下に説明する実施形態に限定されるものでない。 Hereinafter, an electric double layer capacitor and a manufacturing method thereof according to an embodiment of the present invention will be described. Note that the present invention is not limited to the embodiments described below.
　（全体構造）
　電気二重層キャパシタは、分極性電極と電解液との境界面に形成される電気二重層の蓄電作用を利用し、静電容量により電荷の蓄電及び放電を行う受動素子である。この電気二重層キャパシタの素子は、正極、負極、セパレータ及び電解液を備え、巻回形の形態を採る。正極と負極はセパレータを介して対向する。電解液は、コンデンサ素子の空隙部に充填される。 (Overall structure)
An electric double layer capacitor is a passive element that stores and discharges charges through capacitance by utilizing the power storage effect of an electric double layer formed at the interface between a polarizable electrode and an electrolyte. The element of this electric double layer capacitor includes a positive electrode, a negative electrode, a separator, and an electrolyte, and has a wound shape. The positive electrode and the negative electrode face each other with a separator in between. The electrolytic solution fills the void of the capacitor element.
　この素子は、ケースに収容され、封口体で密封されている。ケースは、素子を収容する有底筒状であり、例えばアルミニウム製である。封口体は、ケースの開口に加締め加工により取り付けられ、ケースの開口を封止する。正極と負極には引出端子が接続されている。封口体には、外部に導出する外部端子が取り付けられている。正極及び負極に接続された引出端子と封口体の外部端子は電気的に接続され、これにより電気二重層キャパシタは、回路上に実装可能となっている。または、正極と負極に接続された引出端子が封口体の貫通孔を通って外部に導出されている。 This element is housed in a case and sealed with a sealing body. The case has a cylindrical shape with a bottom that houses the element, and is made of aluminum, for example. The sealing body is attached to the opening of the case by crimping and seals the opening of the case. Lead terminals are connected to the positive and negative electrodes. An external terminal led out to the outside is attached to the sealing body. The lead terminals connected to the positive and negative electrodes and the external terminals of the sealing body are electrically connected, so that the electric double layer capacitor can be mounted on a circuit. Alternatively, the lead terminals connected to the positive electrode and the negative electrode are led out through the through hole of the sealing body.
　（電解液）
　電解液は、溶媒としてスルホラン（以下、ＳＬＦと略すこともある）と鎖状スルホン（以下、ＣＳと略すこともある）を含有している。スルホランと鎖状スルホンの混合比に限定はないが、例えば重量比でＳＬＦ：ＣＳ＝９：１～７：３の範囲が好ましい。この範囲であると、例えば３．０Ｖといった高耐圧及び－２０℃～－３０℃といった低温領域において、電気に樹霜キャパシタの経時的性能劣化を抑制できる。 (electrolyte)
The electrolytic solution contains sulfolane (hereinafter sometimes abbreviated as SLF) and chain sulfone (hereinafter sometimes abbreviated as CS) as a solvent. Although there is no limitation on the mixing ratio of sulfolane and chain sulfone, it is preferable, for example, that the weight ratio of SLF:CS is in the range of 9:1 to 7:3. Within this range, it is possible to suppress deterioration of the performance of the electrical frost capacitor over time, for example, in a high breakdown voltage region of 3.0 V and a low temperature region of -20° C. to -30° C.
　鎖状スルホンとしては、ジメチルスルホン、エチルメチルスルホン、ブチルイソブチルスルホン、イソプロピルメチルスルホン、エチルイソブチルスルホン、又はエチルイソプロピルスルホンが挙げられ、これらの２種以上が混合されてもよい。 Examples of the chain sulfone include dimethylsulfone, ethylmethylsulfone, butylisobutylsulfone, isopropylmethylsulfone, ethylisobutylsulfone, and ethylisopropylsulfone, and two or more of these may be mixed.
　スルホランと鎖状スルホンを重量比でＳＬＦ：ＣＳ＝９：１～７：３の範囲内で混合した混合溶媒（以下、単に混合溶媒ともいう）のサイクリックボルタンメトリーによるボルタモグラムを図１に示す。スルホランと鎖状スルホンの混合液のサイクリックボルタモグラムは、次の通り測定する。即ち、作用極に面積２ｃｍ×２ｃｍ、塗工厚み５１μｍの活性炭電極、対極に面積２ｃｍ×１０ｃｍ、塗工厚み５０μｍの活性炭電極、参照電極にＡｇ／Ａｇ＋参照電極を用いる。１Ｌの混合溶媒当たり２ｍｏｌの５－アゾニアスピロ［４，４］ノナンＢＦ4を添加した溶液を測定溶液とする。浸漬電位から電位走査を開始し、浸漬電位から正側に１．５Ｖまで電位走査を始める。電位走査速度は０．５ｍＶ／ｓとする。また、浸漬電位から電位走査を開始し、浸漬電位から負側に-２．８Ｖまで電位走査を始める。電位走査速度は０．５ｍＶ／ｓとする。 FIG. 1 shows a voltammogram obtained by cyclic voltammetry of a mixed solvent (hereinafter also simply referred to as mixed solvent) in which sulfolane and chain sulfone are mixed in a weight ratio of SLF:CS in the range of 9:1 to 7:3. The cyclic voltammogram of a mixture of sulfolane and chain sulfone is measured as follows. That is, an activated carbon electrode with an area of 2 cm x 2 cm and a coating thickness of 51 μm is used as the working electrode, an activated carbon electrode with an area of 2 cm x 10 cm and a coating thickness of 50 μm as the counter electrode, and an Ag/Ag+reference electrode as the reference electrode. A solution to which 2 mol of 5-azoniaspiro[4,4]nonane BF 4 is added per 1 L of the mixed solvent is used as a measurement solution. Potential scanning is started from the immersion potential, and potential scanning is started from the immersion potential to 1.5 V on the positive side. The potential scanning speed is 0.5 mV/s. Further, potential scanning is started from the immersion potential, and potential scanning is started from the immersion potential to -2.8V on the negative side. The potential scanning speed is 0.5 mV/s.
　図１に示すように、横軸を電位（ｖｓ．　Ａｇ／Ａｇ＋）及び縦軸を電流（ｍＡ）としたときに、スルホランと鎖状スルホンの混合溶媒が電子授受をせずに、電流値がゼロ近辺で、傾きがゼロに近い平坦領域がある。平坦領域は、混合溶媒の電位窓である。 As shown in Figure 1, when the horizontal axis is potential (vs.Ag/Ag+) and the vertical axis is current (mA), the mixed solvent of sulfolane and chain sulfone does not transfer electrons and the current value increases. There is a flat region near zero where the slope is close to zero. The flat region is the potential window of the mixed solvent.
　ここで、面積２ｃｍ×２ｃｍの正極及び負極との間にセパレータを挟み込み、正極と負極を外側からガラス板で挟み込んだ素子を作製する。１Ｌの混合溶媒当たり２ｍｏｌの５－アゾニアスピロ［４，４］ノナンＢＦ4を添加した溶液に、素子を浸漬する。溶液には参照極（Ａｇ/Ａｇ＋）も配置する。そして、この電気二重層キャパシタに対して例えば５Ａの電流で３．０Ｖまで充電し４時間保持する。４時間保持した後、参照極に対する正極と負極の電位を分極電位とする。この測定の結果、混合溶媒の電位窓は－２．４２Ｖ～＋０．７８Ｖの範囲に及ぶ。図１中、点線は負側の電位窓の下限値及び正側の電位窓の上限値である。 Here, a separator is sandwiched between a positive electrode and a negative electrode having an area of 2 cm×2 cm, and an element is produced in which the positive electrode and the negative electrode are sandwiched between glass plates from the outside. The device is immersed in a solution containing 2 mol of 5-azoniaspiro[4,4]nonane BF 4 per 1 L of mixed solvent. A reference electrode (Ag/Ag+) is also placed in the solution. Then, this electric double layer capacitor is charged to 3.0V with a current of 5A, for example, and held for 4 hours. After holding for 4 hours, the potentials of the positive and negative electrodes with respect to the reference electrode are set as polarization potentials. As a result of this measurement, the potential window of the mixed solvent ranges from -2.42V to +0.78V. In FIG. 1, the dotted lines indicate the lower limit of the potential window on the negative side and the upper limit of the potential window on the positive side.
　電解液の電解質としては第４級アンモニウムイオンを生成し得るものであればよく、各種第４級アンモニウム塩から選ばれる１種以上が挙げられる。カチオンとしてテトラメチルアンモニウム、エチルトリメチルアンモニウム、テトラエチルアンモニウム、トリエチルメチルアンモニウム、ジエチルジメチルアンモニウム、メチルエチルピロリジニウム、スピロビピロリジニウム等を挙げることができ、アニオンとしては、ＢＦ４ －、ＰＦ６ －、ＣｌＯ４ －、ＡｓＦ６ －、ＳｂＦ６ －、ＡｌＣｌ４ －、またはＲｆＳＯ３ －、（ＲｆＳＯ２）２Ｎ－、ＲｆＣＯ２ －(Ｒｆは炭素数１～８のフルオロアルキル基)等を挙げることができる。 The electrolyte of the electrolytic solution may be any electrolyte as long as it can generate quaternary ammonium ions, and examples thereof include one or more selected from various quaternary ammonium salts. Cations include tetramethylammonium, ethyltrimethylammonium, tetraethylammonium, triethylmethylammonium, diethyldimethylammonium, methylethylpyrrolidinium, spirobipyrrolidinium, etc., and anions include BF 4 - , PF 6 - , ClO 4 − , AsF 6 − , SbF 6 − , AlCl 4 − , or RfSO 3 − , (RfSO 2 ) 2 N − , RfCO 2 − (Rf is a fluoroalkyl group having 1 to 8 carbon atoms), etc. Can be done.
　典型的には、第４級アンモニウム塩として、テトラメチルアンモニウムＢＦ４、エチルトリメチルアンモニウムＢＦ4、ジエチルジメチルアンモニウムＢＦ4、トリエチルメチルアンモニウムＢＦ4、テトラエチルアンモニウムＢＦ4、スピロビピロリジニウムＢＦ4、メチルエチルピロリジニウムＢＦ4、テトラメチルアンモニウムＰＦ６、エチルトリメチルアンモニウムＰＦ6、ジエチルジメチルアンモニウムＰＦ6、トリエチルメチルアンモニウムＰＦ6、テトラエチルアンモニウムＰＦ6、スピロビピロリジニウムＰＦ6、メチルエチルピロリジニウムＰＦ６、テトラメチルアンモニウムビス（オキサラト）ボレート、エチルトリメチルアンモニウムビス（オキサラト）ボレート、ジエチルジメチルアンモニウムビス（オキサラト）ボレート、トリエチルメチルアンモニウムビス（オキサラト）ボレート、テトラエチルアンモニウムビス（オキサラト）ボレート、スピロビピロリジニウムビス（オキサラト）ボレート、メチルエチルピロリジニウムビス（オキサラト）ボレート、テトラメチルアンモニウムジフルオロオキサラトボレート、エチルトリメチルアンモニウムジフルオロオキサラトボレート、ジエチルジメチルアンモニウムジフルオロオキサラトボレート、トリエチルメチルアンモニウムジフルオロオキサラトボレート、テトラエチルアンモニウムジフルオロオキサラトボレート、スピロビピロリジニウムジフルオロオキサラトボレート、メチルエチルピロリジニウムジフルオロオキサラトボレート等を用いることができる。 Typically, quaternary ammonium salts include tetramethylammonium BF 4 , ethyltrimethylammonium BF 4 , diethyldimethylammonium BF 4 , triethylmethylammonium BF 4 , tetraethylammonium BF 4 , spirobipyrrolidinium BF 4 , methyl Ethylpyrrolidinium BF 4 , Tetramethylammonium PF 6 , Ethyltrimethylammonium PF 6 , Diethyldimethylammonium PF 6 , Triethylmethylammonium PF 6 , Tetraethylammonium PF 6 , Spirobipyrrolidinium PF 6 , Methylethylpyrrolidinium PF 6. Tetramethylammonium bis(oxalato)borate, ethyltrimethylammoniumbis(oxalato)borate, diethyldimethylammoniumbis(oxalato)borate, triethylmethylammoniumbis(oxalato)borate, tetraethylammoniumbis(oxalato)borate, spirobipyrrolidi Niumium bis(oxalato)borate, methylethylpyrrolidinium bis(oxalato)borate, tetramethylammonium difluorooxalatoborate, ethyltrimethylammonium difluorooxalatoborate, diethyldimethylammonium difluorooxalatoborate, triethylmethylammonium difluorooxalatoborate, Tetraethylammonium difluorooxalatoborate, spirobipyrrolidinium difluorooxalatoborate, methylethylpyrrolidinium difluoroxalatoborate, etc. can be used.
　また、添加剤としては、リン酸類及びその誘導体（リン酸、亜リン酸、リン酸エステル類、ホスホン酸類等）、ホウ酸類及びその誘導体（ホウ酸、酸化ホウ酸、ホウ酸エステル類、ホウ素と水酸基及び／又はカルボキシル基を有する化合物との錯体等）、硝酸塩（硝酸リチウム等）、ニトロ化合物（ニトロ安息香酸、ニトロフェノール、ニトロフェネトール、ニトロアセトフェノン、芳香族ニトロ化合物等）等が挙げられる。 In addition, as additives, phosphoric acids and their derivatives (phosphoric acid, phosphorous acid, phosphoric acid esters, phosphonic acids, etc.), boric acids and their derivatives (boric acid, boric acid oxide, boric acid esters, boron and complexes with compounds having a hydroxyl group and/or carboxyl group, etc.), nitrates (lithium nitrate, etc.), nitro compounds (nitrobenzoic acid, nitrophenol, nitrophenethol, nitroacetophenone, aromatic nitro compounds, etc.).
　（電極）
　正極及び負極は、主に集電体と分極性電極層により構成される。集電体は、アルミニウム箔、白金、金、ニッケル、チタン及び鋼等の金属である。集電体の形状は、膜状、箔状、板状、網状、エキスパンドメタル状、円筒状などの任意の形状を採用することができる。また集電体の表面はエッチング処理などによる凹凸面を形成してもよく、またプレーン面であってもよい。 (electrode)
The positive electrode and the negative electrode are mainly composed of a current collector and a polarizable electrode layer. The current collector is a metal such as aluminum foil, platinum, gold, nickel, titanium, and steel. The shape of the current collector may be any shape such as a film, a foil, a plate, a net, an expanded metal, or a cylinder. Further, the surface of the current collector may be formed with an uneven surface by etching or the like, or may be a plain surface.
　分極性電極層は主として活性炭を含有する。活性炭は、やしがら等の天然植物組織、フェノール等の合成樹脂、石炭、コークス、ピッチ等の化石燃料由来のものを原料とし、水蒸気賦活、アルカリ賦活、塩化亜鉛賦活又は電界賦活等の賦活処理並びに開口処理が施されていればよい。 The polarizable electrode layer mainly contains activated carbon. Activated carbon is made from natural plant tissues such as coconut shells, synthetic resins such as phenol, fossil fuels such as coal, coke, and pitch, and is processed through activation treatments such as steam activation, alkali activation, zinc chloride activation, or electric field activation. In addition, it is sufficient that the opening treatment is performed.
　ここで、正極の静電容量Ｃｐとする。また、負極の静電容量Ｃｎとする。このとき、正極の静電容量Ｃｐと負極の静電容量Ｃｎの容量比Ｃｐ：Ｃｎが１．３以上：１となるように、分極性電極層を調整する。正極の静電容量Ｃｐ及び負極の静電容量Ｃｎは、次のようにして測定する。即ち、規定面積の試験片を切り出し、白金板を対向電極としてガラス製の測定槽内の静電容量測定液に浸漬し、静電容量計を用いて計測する。例えば、規定面積は１ｃｍ２とし、静電容量測定液は３０℃の五ホウ酸アンモニウム水溶液とし、静電容量計はポテンショスタットと周波数応答アナライザ、電気化学インピーダンスアナライザー又はＬＣＲメータ等とし、測定条件としてＤＣバイアス電圧は１．５Ｖとし、交流振幅を１Ｖとする。 Here, it is assumed that the capacitance of the positive electrode is Cp. Further, it is assumed that the capacitance of the negative electrode is Cn. At this time, the polarizable electrode layer is adjusted so that the capacitance ratio Cp:Cn between the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode is 1.3 or more:1. The capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode are measured as follows. That is, a test piece of a specified area is cut out, immersed in a capacitance measurement liquid in a glass measurement tank using a platinum plate as a counter electrode, and measured using a capacitance meter. For example, the specified area is 1 cm2 , the capacitance measurement liquid is an ammonium pentaborate aqueous solution at 30°C, the capacitance meter is a potentiostat, a frequency response analyzer, an electrochemical impedance analyzer, an LCR meter, etc., and the measurement conditions are as follows: The DC bias voltage is 1.5V, and the AC amplitude is 1V.
　正極の静電容量Ｃｐを負極の静電容量Ｃｎよりも大きいＣｐ＞Ｃｎとすると、正極の電極電位（ｖｓ．　Ａｇ／Ａｇ＋ＱＲＥ）及び負極の電極電位（ｖｓ．　Ａｇ／Ａｇ＋ＱＲＥ）が卑方向にシフトする。そして、正極の静電容量Ｃｐを負極の静電容量Ｃｎの１．３倍以上にすると、電気二重層キャパシタの耐電圧を３．０Ｖ以上とした場合においても、正極の電極電位及び負極の電極電位が、スルホランと鎖状スルホンの混合溶媒の電位窓範囲に収まる。 When the capacitance Cp of the positive electrode is larger than the capacitance Cn of the negative electrode, Cp>Cn, the electrode potential of the positive electrode (vs. Ag/Ag+QRE) and the electrode potential of the negative electrode (vs. Ag/Ag+QRE) shift in the base direction. do. If the capacitance Cp of the positive electrode is made 1.3 times or more the capacitance Cn of the negative electrode, even if the withstand voltage of the electric double layer capacitor is set to 3.0 V or more, the electrode potential of the positive electrode and the electrode potential of the negative electrode The potential falls within the potential window range of a mixed solvent of sulfolane and chain sulfone.
　そのため、鎖状スルホンが電気化学的に安定し、電気二重層キャパシタの耐電圧が大きくなっても、鎖状スルホンの分解反応電流は小さく、電気二重層キャパシタ内のガス発生が抑制される。但し、正極の静電容量Ｃｐが負極の静電容量Ｃｎの１．７倍以下であることが好ましく、この範囲であれば電気二重層キャパシタの静電容量の低下も抑制できる。 Therefore, even if the chain sulfone becomes electrochemically stable and the withstand voltage of the electric double layer capacitor increases, the decomposition reaction current of the chain sulfone is small, and gas generation within the electric double layer capacitor is suppressed. However, it is preferable that the capacitance Cp of the positive electrode is 1.7 times or less than the capacitance Cn of the negative electrode, and within this range, a decrease in the capacitance of the electric double layer capacitor can also be suppressed.
　例えば、３．０Ｖの耐電圧の電気二重層キャパシタにおいて、正極の静電容量Ｃｐと負極の静電容量Ｃｎの容量比Ｃｐ：Ｃｎを１．３：１とすると、正極の電極電位（ｖｓ．　Ａｇ／Ａｇ＋ＱＲＥ）が＋０．７７Ｖであり、負極の電極電位（ｖｓ．　Ａｇ／Ａｇ＋ＱＲＥ）が－２．１９Ｖであり、スルホランと鎖状スルホンの混合溶媒の電位窓に収まる。また、３．０Ｖの耐電圧の電気二重層キャパシタにおいて、正極の静電容量Ｃｐと負極の静電容量Ｃｎの容量比Ｃｐ：Ｃｎを１．７：１とすると、正極の電極電位（ｖｓ．　Ａｇ／Ａｇ＋ＱＲＥ）が＋０．５８Ｖであり、負極の電極電位（ｖｓ．　Ａｇ／Ａｇ＋ＱＲＥ）が－２．４１Ｖであり、スルホランと鎖状スルホンの混合溶媒の電位窓に収まる。 For example, in an electric double layer capacitor with a withstand voltage of 3.0 V, if the capacitance ratio Cp:Cn of the positive electrode capacitance Cp and the negative electrode capacitance Cn is 1.3:1, then the electrode potential of the positive electrode (vs. Ag/Ag+QRE) is +0.77 V, and the electrode potential of the negative electrode (vs. Ag/Ag+QRE) is -2.19 V, which falls within the potential window of the mixed solvent of sulfolane and chain sulfone. In addition, in an electric double layer capacitor with a withstand voltage of 3.0 V, if the capacitance ratio Cp:Cn of the positive electrode capacitance Cp and the negative electrode capacitance Cn is 1.7:1, then the electrode potential of the positive electrode (vs. Ag/Ag+QRE) is +0.58 V, and the electrode potential of the negative electrode (vs. Ag/Ag+QRE) is -2.41 V, which falls within the potential window of the mixed solvent of sulfolane and chain sulfone.
　尚、正極電位と負極電位は次の通り測定する。即ち、面積２ｃｍ×２ｃｍの正極及び負極との間にセパレータを挟み込み、正極と負極を外側からガラス板で挟み込んだ素子を作製する。１Ｌの混合溶媒当たり２ｍｏｌの５－アゾニアスピロ［４，４］ノナンＢＦ4を添加した溶液に、素子を浸漬する。溶液には参照極（Ａｇ/Ａｇ＋）も配置する。そして、この電気二重層キャパシタに対して例えば５Ａの電流で３．０Ｖまで充電し４時間保持する。４時間保持した後、参照極に対する正極と負極の電位を分極電位とする。 Note that the positive electrode potential and negative electrode potential are measured as follows. That is, a separator is sandwiched between a positive electrode and a negative electrode having an area of 2 cm x 2 cm, and an element is produced in which the positive electrode and the negative electrode are sandwiched between glass plates from the outside. The device is immersed in a solution containing 2 mol of 5-azoniaspiro[4,4]nonane BF 4 per 1 L of mixed solvent. A reference electrode (Ag/Ag+) is also placed in the solution. Then, this electric double layer capacitor is charged to 3.0V with a current of 5A, for example, and held for 4 hours. After holding for 4 hours, the potentials of the positive and negative electrodes with respect to the reference electrode are set as polarization potentials.
　正極の静電容量Ｃｐと負極の静電容量Ｃｎは、各々の分極性電極層の厚みによって調整することもできる。即ち、正極の静電容量Ｃｐと負極の静電容量Ｃｎの容量比Ｃｐ：Ｃｎを１．３：１～１．７：１とするためには、正極の分極性電極層の厚みを、負極の分極性電極層の厚みに対し１．２以上１．５倍以下とすることが好ましい。換言すれば、正極の分極性電極層の厚みＴｐと負極の分極性電極層の厚みＴｎの厚み比Ｔｐ：Ｔｎを１．２：１～１．５：１にすることが好ましい。また、静電容量は箔面積に比例することから、正極の静電容量Ｃｐと負極の静電容量Ｃｎは、各々の箔長によって調整することもできる。 The capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode can also be adjusted by the thickness of each polarizable electrode layer. That is, in order to set the capacitance ratio Cp:Cn between the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode to 1.3:1 to 1.7:1, the thickness of the polarizable electrode layer of the positive electrode should be The thickness is preferably 1.2 or more and 1.5 or less times the thickness of the polarizable electrode layer. In other words, the thickness ratio Tp:Tn of the thickness Tp of the polarizable electrode layer of the positive electrode and the thickness Tn of the polarizable electrode layer of the negative electrode is preferably 1.2:1 to 1.5:1. Furthermore, since the capacitance is proportional to the foil area, the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode can also be adjusted by adjusting the length of each foil.
　分極性電極層は、例えば、活性炭とバインダーのスラリーをドクターブレード法等によって集電体上に塗工し、乾燥することにより電極を形成すればよい。炭素材料とバインダーの混合物をシート状に成型し、集電体に圧着するようにしてもよい。バインダーとしては、例えばフッ素系ゴム、ジエン系ゴム、スチレン系ゴム等のゴム類、ポリテトラフルオロエチレン、ポリフッ化ビニリデン等の含フッ素ポリマー、カルボキシメチルセルロース、ニトロセルロース等のセルロース、その他、ポリオレフィン樹脂、ポリイミド樹脂、アクリル樹脂、ニトリル樹脂、ポリエステル樹脂、フェノール樹脂、ポリ酢酸ビニル樹脂、ポリビニルアルコール樹脂、エポキシ樹脂などを挙げることができる。これらのバインダーは、単独で使用しても良く、２種以上を混合して使用してもよい。 The polarizable electrode layer may be formed by, for example, applying a slurry of activated carbon and a binder onto the current collector using a doctor blade method or the like and drying it. A mixture of the carbon material and the binder may be formed into a sheet shape, and the sheet may be pressure-bonded to the current collector. Examples of the binder include rubbers such as fluorine rubber, diene rubber, and styrene rubber, fluorine-containing polymers such as polytetrafluoroethylene and polyvinylidene fluoride, celluloses such as carboxymethyl cellulose and nitrocellulose, and other materials such as polyolefin resins and polyimides. Examples include resins, acrylic resins, nitrile resins, polyester resins, phenol resins, polyvinyl acetate resins, polyvinyl alcohol resins, and epoxy resins. These binders may be used alone or in combination of two or more.
　尚、分極性電極層には、導電助剤を含めてもよい。導電助剤としては、ケッチェンブラック、アセチレンブラック、チャネルブラックなどのカーボンブラック、カーボンナノホーン、無定形炭素、天然黒鉛、人造黒鉛、黒鉛化ケッチェンブラック、メソポーラス炭素、カーボンナノチューブ、カーボンナノファイバなどが挙げられる。カーボンナノチューブは、グラフェンシートが１層である単層カーボンナノチューブ（ＳＷＣＮＴ）でも、２層以上のグラフェンシートが同軸状に丸まり、チューブ壁が多層をなす多層カーボンナノチューブ（ＭＷＣＮＴ）でもよく、それらが混合されていてもよい。 Note that the polarizable electrode layer may contain a conductive additive. Examples of conductive additives include carbon black such as Ketjen black, acetylene black, and channel black, carbon nanohorn, amorphous carbon, natural graphite, artificial graphite, graphitized Ketjen black, mesoporous carbon, carbon nanotubes, and carbon nanofibers. Can be mentioned. Carbon nanotubes can be single-walled carbon nanotubes (SWCNTs), which have a single layer of graphene sheets, or multi-walled carbon nanotubes (MWCNTs), which have two or more layers of graphene sheets rolled coaxially and have multiple tube walls, or they can be mixed. may have been done.
　また、集電体の表面には、集電体の水和や酸化を抑制するリンを付着させるようにしてもよい。例えば、集電体をリン酸水溶液又はリン酸塩水溶液に浸漬する。更に、集電体と分極性電極層の間には、黒鉛等の導電剤を含むカーボンコート層を設けてもよい。集電体の表面に黒鉛等の導電剤、バインダー等を含むスラリーを塗布、乾燥することで、カーボンコート層を形成することができる。 Additionally, phosphorus that suppresses hydration and oxidation of the current collector may be attached to the surface of the current collector. For example, the current collector is immersed in an aqueous phosphoric acid solution or an aqueous phosphate solution. Furthermore, a carbon coat layer containing a conductive agent such as graphite may be provided between the current collector and the polarizable electrode layer. A carbon coat layer can be formed by applying a slurry containing a conductive agent such as graphite, a binder, etc. to the surface of a current collector and drying the slurry.
　このような正極及び負極は、長尺の帯形状を有し、セパレータの介在の上で渦巻き状に巻回される。正極及び負極において、渦巻きに沿う方向を帯長さ方向といい、一般的には、正極と負極は、長尺方向に沿って巻き込まれ、この長尺方向が帯長さ方向となる。 Such a positive electrode and a negative electrode have a long band shape and are spirally wound with a separator interposed therebetween. In the positive and negative electrodes, the direction along the spiral is called the band length direction, and generally, the positive and negative electrodes are wound along the longitudinal direction, and this longitudinal direction is the band length direction.
　図２は、正極と負極の巻回方法を示す模式図であり、点線が正極で、実線が負極である。図２に示すように、正極と負極とを帯長さ方向の長さで比べたとき、負極が正極よりも帯長さ方向が長くなり、負極が最内周及び最外周となるようにし、負極の巻き始めと巻き終わりに正極と対向しない負極非対向部分を形成する。即ち、素子は、負極を先巻き始め側かつ後巻き終わり側として形成する。先んじて負極を一周以上巻き込み、負極とセパレータと正極の層において負極が内周側で正極が外周側になるように巻きながら、最外周では負極を正極の端部を超えて最後に巻き終えることで、負極箔を最内周及び最外周に位置させる。 FIG. 2 is a schematic diagram showing a method of winding a positive electrode and a negative electrode, with the dotted line representing the positive electrode and the solid line representing the negative electrode. As shown in FIG. 2, when the positive electrode and the negative electrode are compared in length in the band length direction, the negative electrode is longer in the band length direction than the positive electrode, and the negative electrode is the innermost circumference and the outermost circumference, Negative electrode non-facing portions that do not face the positive electrode are formed at the beginning and end of winding the negative electrode. That is, the element is formed with the negative electrode as the first winding start side and the second winding end side. Wrap the negative electrode one or more times in advance, and wrap the layer of the negative electrode, separator, and positive electrode so that the negative electrode is on the inner side and the positive electrode on the outer side, and at the outermost circumference, wrap the negative electrode past the end of the positive electrode and finish winding last. Then, the negative electrode foils are positioned at the innermost and outermost peripheries.
　負極の静電容量Ｃｐを負極の静電容量Ｃｎよりも大きくすることで、正極の電極電位及び負極の電極電位は卑方向へシフトするが、負極に非対向部分を生じさせることで、この卑方向へのシフトは更に大きくなる。従って、負極の電極電位及び正極の電極電位が混合溶媒の電位窓の範囲に益々収まり易くなり、鎖状スルホンが電気化学的に安定する。 By making the capacitance Cp of the negative electrode larger than the capacitance Cn of the negative electrode, the electrode potential of the positive electrode and the electrode potential of the negative electrode are shifted to the base direction. The shift in direction becomes even larger. Therefore, the electrode potential of the negative electrode and the electrode potential of the positive electrode are more likely to fall within the potential window of the mixed solvent, and the chain sulfone becomes electrochemically stable.
　（セパレータ）
　セパレータは、正極箔と負極箔の接触を防止する。セパレータとしては、クラフト、マニラ麻、エスパルト、ヘンプ、レーヨン等のセルロースおよびこれらの混合紙、ポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリエチレンナフタレート、それらの誘導体などのポリエステル系樹脂、ポリテトラフルオロエチレン系樹脂、ポリフッ化ビニリデン系樹脂、ビニロン系樹脂、脂肪族ポリアミド、半芳香族ポリアミド、全芳香族ポリアミド等のポリアミド系樹脂、ポリイミド系樹脂、ポリエチレン樹脂、ポリプロピレン樹脂、トリメチルペンテン樹脂、ポリフェニレンサルファイド樹脂、アクリル樹脂等が挙げられ、これらの樹脂を単独で又は混合して用いることができる。 (separator)
The separator prevents contact between the positive electrode foil and the negative electrode foil. As a separator, cellulose such as kraft, Manila hemp, esparto, hemp, rayon, and mixed paper thereof, polyester resin such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and their derivatives, polytetrafluoroethylene resin, polyfluoroethylene resin, etc. Polyamide resins such as vinylidene chloride resin, vinylon resin, aliphatic polyamide, semi-aromatic polyamide, fully aromatic polyamide, polyimide resin, polyethylene resin, polypropylene resin, trimethylpentene resin, polyphenylene sulfide resin, acrylic resin, etc. These resins can be used alone or in combination.
　（製法）
　このような電気二重層キャパシタは、正極形成工程、負極電極工程、素子形成工程、電解液含浸工程を経て製造される。正極形成工程では、集電体上に分極性電極層を形成して、分極性電極層の調整により、電極電位（ｖｓ．　Ａｇ／Ａｇ＋）が＋０．５８Ｖ～＋０．７８Ｖの範囲の正極を形成する。また、負極形成工程では、集電体上に分極性電極層を形成して、分極性電極層の調整により、電極電位（ｖｓ．　Ａｇ／Ａｇ＋）が－２．４２Ｖ～－２．１９Ｖの範囲の負極を形成する。 (Manufacturing method)
Such an electric double layer capacitor is manufactured through a positive electrode forming process, a negative electrode forming process, an element forming process, and an electrolyte impregnation process. In the positive electrode forming step, a polarizable electrode layer is formed on the current collector, and a positive electrode with an electrode potential (vs. Ag/Ag+) in the range of +0.58V to +0.78V is formed by adjusting the polarizable electrode layer. do. In addition, in the negative electrode forming step, a polarizable electrode layer is formed on the current collector, and by adjusting the polarizable electrode layer, the electrode potential (vs. Ag/Ag+) is in the range of -2.42V to -2.19V. form the negative electrode.
　素子形成工程では、正極と負極をセパレータの介在の上で渦巻き状に巻回する。このとき、先んじて負極を一周以上巻き込み、正極とセパレータと負極の層において負極が内周側で正極が外周側になるように巻きながら、最外周では負極を正極の端部を超えて最後に巻き終えることで、負極箔を最内周及び最外周に位置させる。 In the element forming step, a positive electrode and a negative electrode are spirally wound with a separator interposed therebetween. At this time, first wrap the negative electrode one or more times around the layer of the positive electrode, separator, and negative electrode so that the negative electrode is on the inner circumferential side and the positive electrode is on the outer circumferential side. By completing the winding, the negative electrode foil is positioned at the innermost and outermost peripheries.
　電解液含浸工程では、スルホランと鎖状スルホンを重量比でＳＬＦ：ＣＳ＝９：１～７：３の範囲内で混合し、この混合溶媒を主溶媒として含む電解液を素子に含浸させる。含浸は減圧下で行ってもよい。素子に電解液を含浸させた後、素子をケースに入れて封口体で封止する。 In the electrolyte impregnation step, sulfolane and chain sulfone are mixed in a weight ratio of SLF:CS=9:1 to 7:3, and the element is impregnated with an electrolyte containing this mixed solvent as the main solvent. Impregnation may also be carried out under reduced pressure. After the element is impregnated with the electrolyte, the element is placed in a case and sealed with a sealing body.
　以下、実施例に基づいて本発明をさらに詳細に説明する。なお、本発明は下記実施例に限定されるものではない。 Hereinafter, the present invention will be explained in more detail based on Examples. Note that the present invention is not limited to the following examples.
　次の通り、実施例１乃至３並びに比較例１の耐電圧が３．０Ｖの電気二重層キャパシタを作製した。即ち、水蒸気賦活活性炭、カーボンブラック、分散剤としてカルボキシメチルセルロース、バインダーとしてＳＢＲエマルジョン及び純水を混合してスラリーを得た。また、アルミ箔の表面に黒鉛を含む塗料を塗布し、アルミ箔表面のカーボンコート層をアルミ箔両面に形成させることで、集電箔を作製した。作製した集電箔の両面に、同じく作製したスラリーを塗布して乾燥させ、帯幅方向の長さが同一の正極及び負極を作製した。 Electric double layer capacitors of Examples 1 to 3 and Comparative Example 1 with a withstand voltage of 3.0 V were manufactured as follows. That is, a slurry was obtained by mixing steam-activated carbon, carbon black, carboxymethyl cellulose as a dispersant, SBR emulsion as a binder, and pure water. In addition, a current collector foil was prepared by applying a paint containing graphite to the surface of the aluminum foil to form a carbon coat layer on both sides of the aluminum foil. A similarly prepared slurry was applied to both sides of the prepared current collector foil and dried to produce a positive electrode and a negative electrode having the same length in the band width direction.
　正極及び負極の帯長さ方向に延びる中心線を揃え、レーヨンセパレータを介して重ね合わせ、巻回型の素子を形成した。素子においては負極を先巻き始め及び後巻き終わりとした。先んじて負極を巻き込み、正極とセパレータと負極の層において負極が内周側で正極が外周側になるように巻きながら、最外周では負極を正極の端部を超えて最後に巻き終えるようにした。従って、負極の巻き始めと巻き終わりに正極と対向しない負極非対向部分が形成されている。尚、負極非対向部分の活性炭の量は、実施例１乃至３及び比較例１で共通であり、負極に塗工された活性炭全量に対する６ｗｔ％である。 The center lines of the positive and negative electrodes extending in the band length direction were aligned and overlapped with a rayon separator interposed therebetween to form a wound type element. In the device, the negative electrode was placed at the beginning of the first winding and at the end of the second winding. The negative electrode was rolled in first, and the layer of positive electrode, separator, and negative electrode was wound so that the negative electrode was on the inner circumferential side and the positive electrode on the outer circumferential side, and at the outermost circumference, the negative electrode was wound last beyond the end of the positive electrode. . Therefore, negative electrode non-facing portions that do not face the positive electrode are formed at the beginning and end of winding the negative electrode. The amount of activated carbon in the portion not facing the negative electrode was the same in Examples 1 to 3 and Comparative Example 1, and was 6 wt % based on the total amount of activated carbon coated on the negative electrode.
　この素子に電解液を含浸させた。電解液の溶質として、２．０Ｍの５－アゾニアスピロ［４，４］ノナンＢＦ4を用いた。２．０Ｍとは、１Ｌの電解液に対する電解質のモル数（ｍｏｌ／Ｌ）を表す。電解液の溶媒はスルホランとジメチルスルホンの混合溶媒であり、重量比でＳＬＦ：ＣＳ＝９：１とした。この電解液を素子に含浸させ、電解液が含浸した素子をφ１８×５０Ｌのケースに入れて封口体で封入した。 This element was impregnated with an electrolyte. 2.0M 5-azoniaspiro[4,4]nonane BF 4 was used as the solute in the electrolyte. 2.0M represents the number of moles of electrolyte (mol/L) with respect to 1L of electrolyte solution. The solvent of the electrolytic solution was a mixed solvent of sulfolane and dimethylsulfone, and the weight ratio was SLF:CS=9:1. The element was impregnated with this electrolytic solution, and the element impregnated with the electrolytic solution was placed in a case of φ18×50 L and sealed with a sealing body.
　実施例１乃至４並びに比較例１の電気二重層キャパシタは、下表１に示すように、分極性電極層の塗工厚、正極及び負極の長さが異なっており、これにより、正極の静電容量Ｃｐと負極の静電容量Ｃｎの容量比Ｃｐ：Ｃｎが異なる。
　（表１）
Figure JPOXMLDOC01-appb-I000001
As shown in Table 1 below, the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1 differ in the coating thickness of the polarizable electrode layer and the lengths of the positive electrode and negative electrode. The capacitance ratio Cp:Cn between the capacitance Cp and the capacitance Cn of the negative electrode is different.
(Table 1)
Figure JPOXMLDOC01-appb-I000001
　尚、３．０Ｖの範囲で正極と負極の電位が１：１のとき、容量比Ｃｐ：Ｃｎは１．２：１となることから、容量比算出の際には正極側の容量Ｃｐに係数１．２をかけた。この乗算の理由としては、正極側がカチオン成分とアニオン成分のイオンサイズの差、及び正極側の反応電流の大きさを考慮したためである。 In addition, when the potential of the positive electrode and negative electrode is 1:1 in the range of 3.0 V, the capacitance ratio Cp:Cn is 1.2:1, so when calculating the capacitance ratio, a coefficient is added to the capacitance Cp on the positive electrode side. Multiplied by 1.2. The reason for this multiplication is that the difference in ion size between the cation component and the anion component on the positive electrode side and the magnitude of the reaction current on the positive electrode side are taken into consideration.
　表１に示すように、正極の分極性電極層の厚みＴｐと負極の分極性電極層の厚みＴｎの厚み比Ｔｐ：Ｔｎが１．２：１～１．５：１であると、正極の静電容量Ｃｐと負極の静電容量Ｃｎの容量比Ｃｐ：Ｃｎが１．３：１～１．７：１に調整可能であることも確認された。 As shown in Table 1, when the thickness ratio Tp:Tn of the thickness Tp of the polarizable electrode layer of the positive electrode and the thickness Tn of the polarizable electrode layer of the negative electrode is 1.2:1 to 1.5:1, It was also confirmed that the capacitance ratio Cp:Cn between the capacitance Cp and the capacitance Cn of the negative electrode can be adjusted to 1.3:1 to 1.7:1.
　（正負極の電位測定試験）
　実施例１乃至４並びに比較例１の電気二重層キャパシタの正極及び負極の電極電位Ｖ（ｖｓ．　Ａｇ／Ａｇ＋）を測定した。電極電位Ｖの測定方法及び条件は次の通りである。即ち、実施例１乃至４並びに比較例１の素子を電解液に浸漬した。素子にも当該電解液を含浸させておいた。素子の最外周に参照極（Ａｇ/Ａｇ＋）を配置した。そして、５Ａで３．０Ｖまで充電し４時間保持した。４時間保持後の参照極に対する正負極の電位を分極電位とした。 (Potential measurement test of positive and negative electrodes)
The electrode potentials V (vs. Ag/Ag+) of the positive and negative electrodes of the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1 were measured. The method and conditions for measuring the electrode potential V are as follows. That is, the elements of Examples 1 to 4 and Comparative Example 1 were immersed in an electrolytic solution. The element was also impregnated with the electrolyte. A reference electrode (Ag/Ag+) was placed at the outermost periphery of the element. Then, it was charged to 3.0V at 5A and held for 4 hours. The potential of the positive and negative electrodes with respect to the reference electrode after holding for 4 hours was defined as the polarization potential.
　実施例１乃至４並びに比較例１の電極電位Ｖの測定結果を下表２に示す。
　（表２）
Figure JPOXMLDOC01-appb-I000002
The measurement results of the electrode potential V of Examples 1 to 4 and Comparative Example 1 are shown in Table 2 below.
(Table 2)
Figure JPOXMLDOC01-appb-I000002
　更に、上表２に基づき、スルホランと鎖状スルホンの混合溶媒のサイクリックボルタモグラム上に各電極電位を記載した。その結果を図３乃至７に示す。図３は比較例１の正負の電極電位を示し、図４は実施例１の正負の電極電位を示し、図５は実施例２の正負の電極電位を示し、図６は実施例３の正負の電極電位を示し、図７は実施例４の正負の電極電位を示す。図中、点線は電位窓の負側の下限値及び正側の上限値であり、実線は正極の電極電位と負極の電極電位である。 Further, based on Table 2 above, each electrode potential was written on the cyclic voltammogram of the mixed solvent of sulfolane and chain sulfone. The results are shown in FIGS. 3 to 7. 3 shows the positive and negative electrode potentials of Comparative Example 1, FIG. 4 shows the positive and negative electrode potentials of Example 1, FIG. 5 shows the positive and negative electrode potentials of Example 2, and FIG. 6 shows the positive and negative electrode potentials of Example 3. 7 shows the positive and negative electrode potentials of Example 4. In the figure, the dotted line is the lower limit value on the negative side and the upper limit value on the positive side of the potential window, and the solid line is the electrode potential of the positive electrode and the electrode potential of the negative electrode.
　表２並びに図３乃至７に示すように、実施例１乃至４並びに比較例１の負極と正極の電位差は全て３．０Ｖであり、耐電圧が３．０Ｖの電気二重層キャパシタが作製されている。 As shown in Table 2 and FIGS. 3 to 7, the potential differences between the negative electrode and the positive electrode in Examples 1 to 4 and Comparative Example 1 were all 3.0 V, and electric double layer capacitors with a withstand voltage of 3.0 V were fabricated. There is.
　しかし、正極と負極の容量Ｃｐ：Ｃｎが１．１３：１の比較例１は、負極の電極電位はスルホランと鎖状スルホンの混合溶媒の電位窓の範囲内であるが、正極の電極電位は混合溶媒の電位窓の上限から大きく逸脱してしまい、傾斜が急峻に変化した範囲に属している。 However, in Comparative Example 1 where the capacity Cp:Cn of the positive electrode and negative electrode is 1.13:1, the electrode potential of the negative electrode is within the potential window of the mixed solvent of sulfolane and chain sulfone, but the electrode potential of the positive electrode is It deviates significantly from the upper limit of the potential window of the mixed solvent and belongs to a range where the slope changes steeply.
　一方、正極と負極の容量Ｃｐ：Ｃｎが１．３以上：１の範囲である実施例１乃至３では、正極の電極電位も負極の電極電位もスルホランと鎖状スルホンの混合溶媒の電位窓の範囲内に収まっている。正極と負極の容量Ｃｐ：Ｃｎが１．９１：１の範囲である実施例４も、正極の電極電位がスルホランと鎖状スルホンの混合溶媒の電位窓の範囲内に収まり、負極の電極電位が当該電極窓の下限に近接している。 On the other hand, in Examples 1 to 3 in which the capacitance Cp:Cn of the positive electrode and negative electrode is in the range of 1.3 or more:1, the electrode potential of the positive electrode and the electrode potential of the negative electrode are within the potential window of the mixed solvent of sulfolane and chain sulfone. It is within the range. In Example 4 where the capacity Cp:Cn of the positive electrode and negative electrode is in the range of 1.91:1, the electrode potential of the positive electrode falls within the range of the potential window of the mixed solvent of sulfolane and chain sulfone, and the electrode potential of the negative electrode falls within the range of the potential window of the mixed solvent of sulfolane and chain sulfone. It is close to the lower limit of the electrode window.
　（ガス発生量測定試験）
　このような実施例１乃至４並びに比較例１の電気二重層キャパシタ内に発生するガスの量を測定した。ガス発生量の測定では、各電気二重層キャパシタを６５℃の温度環境下で３．０Ｖの定電圧を印加し続け、３０００時間経過後のケースの膨れ量を求めた。ケースの膨れ量は、３０００時間経過後のケースの最大長手寸法から試験前のケースの最大長手寸法を差分することで得られた。 (Gas generation amount measurement test)
The amount of gas generated in the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1 was measured. To measure the amount of gas generated, a constant voltage of 3.0 V was continuously applied to each electric double layer capacitor in a temperature environment of 65° C., and the amount of swelling of the case after 3000 hours was determined. The amount of swelling of the case was obtained by subtracting the maximum longitudinal dimension of the case before the test from the maximum longitudinal dimension of the case after 3000 hours.
　実施例１乃至４並びに比較例１の電気二重層キャパシタのケース膨れ量の結果を下表３に示す。
　（表３）
Figure JPOXMLDOC01-appb-I000003
Table 3 below shows the results of case swelling amounts of the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1.
(Table 3)
Figure JPOXMLDOC01-appb-I000003
　更に、上表３に基づき、実施例１乃至４並びに比較例１の電気二重層キャパシタのケース膨れ量の結果を図８のグラフに示した。図８は、３０００時間放置後のケース膨れ量を示すグラフであり、横軸は負極の容量Ｃｎに対する正極の容量Ｃｐの比であり、縦軸はケースの膨れ量である。 Furthermore, based on Table 3 above, the results of the case swelling amounts of the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1 are shown in the graph of FIG. FIG. 8 is a graph showing the amount of swelling of the case after being left for 3000 hours, where the horizontal axis is the ratio of the positive electrode capacitance Cp to the negative electrode capacitance Cn, and the vertical axis is the swelling amount of the case.
　表３及び図８に示すように、比較例１の電気二重層キャパシタに比べて、実施例１乃至４の電気二重層キャパシタのケースの膨れ量は少なく抑えられていることが確認された。実施例１乃至４の電気二重層キャパシタは、正極の容量Ｃｐが負極の容量Ｃｎの１．３倍以上であり、正極の電極電位はスルホランと鎖状スルホンの混合溶媒の電位窓の範囲内に収まり、負極の電極電位は当該電極窓に収まっているか、下限に近接している。 As shown in Table 3 and FIG. 8, it was confirmed that the amount of swelling of the cases of the electric double layer capacitors of Examples 1 to 4 was suppressed to be smaller than that of the electric double layer capacitor of Comparative Example 1. In the electric double layer capacitors of Examples 1 to 4, the capacity Cp of the positive electrode is 1.3 times or more the capacity Cn of the negative electrode, and the electrode potential of the positive electrode is within the potential window of the mixed solvent of sulfolane and chain sulfone. The electrode potential of the negative electrode is within the electrode window or is close to the lower limit.
　（静電容量測定試験）
　次に、実施例１乃至４並びに比較例１の電気二重層キャパシタに６５℃で３．０Ｖの定電圧を印加し、初期の放電容量と各時間経過後の放電容量を測定し、容量変化率ΔＣａｐ（％）を算出した。 (Capacitance measurement test)
Next, a constant voltage of 3.0V was applied to the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1 at 65°C, and the initial discharge capacity and the discharge capacity after each time elapsed were measured. ΔCap (%) was calculated.
　実施例１乃至４並びに比較例１の電気二重層キャパシタの静電容量は、定電流放電法に従って測定した。即ち、２０℃の温度環境下において３．０Ｖの定電圧を印加し、２０分間かけて電気二重層キャパシタを充電した。充電完了後に速やかに定電流Ｉで放電を行い、ＩＲドロップを省いた計測開始電圧から計測終了電圧１．３５Ｖに降下するのに要した所要時間Ｔを測定した。そして、定電流Ｉと所要時間Ｔの積と、計測開始電圧と計測終了電圧の差（Ｖ）とから、容量（Ｆ）を算出した。測定は４回行い、平均値を採用した。 The capacitances of the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1 were measured according to a constant current discharge method. That is, a constant voltage of 3.0 V was applied in a temperature environment of 20° C., and the electric double layer capacitor was charged over 20 minutes. Immediately after charging was completed, the battery was discharged at a constant current I, and the time T required for the voltage to drop from the measurement start voltage excluding IR drop to the measurement end voltage of 1.35V was measured. Then, the capacity (F) was calculated from the product of the constant current I and the required time T and the difference (V) between the measurement start voltage and the measurement end voltage. The measurement was performed four times, and the average value was used.
　実施例１乃至４並びに比較例１の電気二重層キャパシタの容量変化率ΔＣａｐ（％）の経時変化を下表４に示す。
　（表４）
Figure JPOXMLDOC01-appb-I000004
Table 4 below shows changes over time in the capacitance change rate ΔCap (%) of the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1.
(Table 4)
Figure JPOXMLDOC01-appb-I000004
　また、上表４に基づき、実施例１乃至４並びに比較例１の電気二重層キャパシタの容量変化率ΔＣａｐ（％）の経時変化を図９に示す。図９は各電気二重層キャパシタの容量変化率ΔＣａｐ（％）の経時変化を比較したグラフである。尚、図９中、ｘ印のプロットのグラフが比較例１を示し、白抜き四角印のプロットのグラフが実施例１を示し、星印のプロットのグラフが実施例２を示し、塗りつぶしの四角印のプロットのグラフが実施例３を示し、三角印のプロットのグラフが実施例４を示す。 Furthermore, based on Table 4 above, FIG. 9 shows changes over time in the capacitance change rate ΔCap (%) of the electric double layer capacitors of Examples 1 to 4 and Comparative Example 1. FIG. 9 is a graph comparing the changes over time in the capacitance change rate ΔCap (%) of each electric double layer capacitor. In FIG. 9, the graph plotted with x marks indicates Comparative Example 1, the graph plotted with white square marks indicates Example 1, the graph plotted with asterisks indicates Example 2, and the graph plotted with filled squares indicates Example 2. The graph plotted with marks indicates Example 3, and the graph plotted with triangle marks indicates Example 4.
　表４及び図９に示すように、実施例１及び２の電気二重層キャパシタは、比較例１の電気二重層キャパシタと比べて、経時的な静電容量の減少が抑制されていることが確認できる。実施例３の電気二重層キャパシタも、比較例１の電気二重層キャパシタと比べて、経時的な静電容量の減少は遜色ない。 As shown in Table 4 and FIG. 9, it was confirmed that the electric double layer capacitors of Examples 1 and 2 suppressed the decrease in capacitance over time compared to the electric double layer capacitor of Comparative Example 1. can. The electric double layer capacitor of Example 3 is also comparable to the electric double layer capacitor of Comparative Example 1 in terms of decrease in capacitance over time.
　このように、正極と負極の容量Ｃｐ：Ｃｎが１．３以上：１の実施例１乃至４については、正極の電極電位はスルホランと鎖状スルホンの混合溶媒の電位窓の範囲内に収まり、負極の電極電位は当該電極窓に収まっているか、下限に近接していることが確認された。そして、ガス発生量測定試験と静電容量測定試験に基づき、この混合溶媒の電位窓に正極及び電極電位が収まることで、耐電圧を３．０Ｖ以上としても、電気二重層キャパシタ内のガスの発生量が抑制され、且つ経時的な静電容量の減少も抑制されていることが確認された。 As described above, for Examples 1 to 4 in which the capacity Cp:Cn of the positive electrode and negative electrode is 1.3 or more: 1, the electrode potential of the positive electrode falls within the range of the potential window of the mixed solvent of sulfolane and chain sulfone, It was confirmed that the electrode potential of the negative electrode was within the electrode window or close to the lower limit. Based on the gas generation amount measurement test and capacitance measurement test, the positive electrode and electrode potentials are within the potential window of this mixed solvent, so that even if the withstand voltage is 3.0V or more, the gas inside the electric double layer capacitor is It was confirmed that the amount generated was suppressed and the decrease in capacitance over time was also suppressed.

Claims (8)

  1. 　正極と負極とをセパレータを介して巻回した素子に電解液を含浸させて成る電気二重層キャパシタであって、
    　前記電解液は、溶媒としてスルホランと鎖状スルホンを含有し、
    　前記正極の静電容量Ｃｐと前記負極の静電容量Ｃｎの容量比Ｃｐ：Ｃｎは、１．３以上：１であること、
    　を特徴とする電気二重層キャパシタ。     An electric double layer capacitor comprising an element in which a positive electrode and a negative electrode are wound with a separator interposed therebetween and impregnated with an electrolyte,
    The electrolytic solution contains sulfolane and chain sulfone as a solvent,
    The capacitance ratio Cp:Cn of the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode is 1.3 or more:1;
    An electric double layer capacitor featuring:
  2. 　前記正極の静電容量Ｃｐと前記負極の静電容量Ｃｎの容量比Ｃｐ：Ｃｎは、１．３：１～１．７：１であること、
    　を特徴とする請求項１記載の電気二重層キャパシタ。     The capacitance ratio Cp:Cn of the capacitance Cp of the positive electrode and the capacitance Cn of the negative electrode is 1.3:1 to 1.7:1;
    The electric double layer capacitor according to claim 1, characterized in that:
  3. 　前記鎖状スルホンは、ジメチルスルホンであること、
    　を特徴とする請求項１記載の電気二重層キャパシタ。     the chain sulfone is dimethyl sulfone;
    The electric double layer capacitor according to claim 1, characterized in that:
  4. 　前記正極と前記負極は、各々が、集電体と当該集電体上の分極性電極層とを有し、
    　前記正極の分極性電極層の厚みは、前記負極の分極性電極層の厚みに対し１．２倍以上１．５倍以下であること、
    　を特徴とする請求項１記載の電気二重層キャパシタ。     The positive electrode and the negative electrode each have a current collector and a polarizable electrode layer on the current collector,
    The thickness of the polarizable electrode layer of the positive electrode is not less than 1.2 times and not more than 1.5 times the thickness of the polarizable electrode layer of the negative electrode;
    The electric double layer capacitor according to claim 1, characterized in that:
  5. 　前記正極の電極電位（ｖｓ　Ａｇ／Ａｇ＋）及び前記負極の電極電位（ｖｓ　Ａｇ／Ａｇ＋）がスルホランと鎖状スルホンの混合溶媒の電位窓内に含まれること、
    　を特徴とする請求項１乃至４の何れかに記載の電気二重層キャパシタ。     The electrode potential of the positive electrode (vs Ag/Ag+) and the electrode potential of the negative electrode (vs Ag/Ag+) are included within the potential window of the mixed solvent of sulfolane and chain sulfone;
    The electric double layer capacitor according to any one of claims 1 to 4, characterized in that:
  6. 　前記正極の電極電位（ｖｓ　Ａｇ／Ａｇ＋）が＋０．５８Ｖ～＋０．７８Ｖの範囲であり、
    　前記負極の電極電位（ｖｓ　Ａｇ／Ａｇ＋）が－２．４２Ｖ～－２．１９Ｖの範囲であること、
    　を特徴とする請求項５記載の電気二重層キャパシタ。     The electrode potential (vs Ag/Ag+) of the positive electrode is in the range of +0.58V to +0.78V,
    The electrode potential (vs Ag/Ag+) of the negative electrode is in the range of -2.42V to -2.19V;
    The electric double layer capacitor according to claim 5, characterized in that:
  7. 　前記負極の帯長さは、前記正極よりも長く、
    　前記素子は、前記負極が最内周及び最外周に位置するように巻回され、
    　前記負極は、前記正極よりも帯長さ方向において巻き始め及び巻き終わりではみ出すこと、
    　を特徴とする請求項１乃至４の何れかに記載の電気二重層キャパシタ。     The band length of the negative electrode is longer than that of the positive electrode,
    The element is wound so that the negative electrode is located at the innermost circumference and the outermost circumference,
    The negative electrode protrudes beyond the positive electrode at the beginning and end of winding in the belt length direction;
    The electric double layer capacitor according to any one of claims 1 to 4, characterized in that:
  8. 　電極電位（ｖｓ．　Ａｇ／Ａｇ＋）が＋０．５８Ｖ～＋０．７８Ｖの範囲の正極を形成する正極形成工程と、
    　電極電位（ｖｓ．　Ａｇ／Ａｇ＋）が－２．４２Ｖ～－２．１９Ｖの範囲の負極を形成する負極形成工程と、
    　前記正極と前記負極とをセパレータを介して巻回して素子を形成する素子形成工程と、
    　前記素子に溶媒としてスルホランと鎖状スルホンを含有する電解液を含浸させる電解液含浸工程と、
    　を含むこと、
    　を特徴とする電気二重層キャパシタの製造方法。     a positive electrode forming step of forming a positive electrode with an electrode potential (vs. Ag/Ag+) in the range of +0.58V to +0.78V;
    a negative electrode forming step of forming a negative electrode with an electrode potential (vs.Ag/Ag+) in the range of -2.42V to -2.19V;
    an element forming step of forming an element by winding the positive electrode and the negative electrode with a separator in between;
    an electrolytic solution impregnation step of impregnating the element with an electrolytic solution containing sulfolane and chain sulfone as a solvent;
    including;
    A method for manufacturing an electric double layer capacitor characterized by:
PCT/JP2023/022648 2022-06-29 2023-06-19 Electric double layer capacitor and method for producing same WO2024004740A1 (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0665206B2 (en) * 1985-03-07 1994-08-22 松下電器産業株式会社 Electric double layer capacitor
JPH10270293A (en) * 1997-03-26 1998-10-09 Matsushita Electric Ind Co Ltd Electric double layer capacitor
JP2000286161A (en) * 1999-01-26 2000-10-13 Seiko Instruments Inc Electric double-layer capacitor
JP2007201118A (en) * 2006-01-26 2007-08-09 Matsushita Electric Ind Co Ltd Wound electric double-layer capacitor
JP2013175619A (en) * 2012-02-27 2013-09-05 Panasonic Corp Electrolyte used for electric double layer capacitor and electric double layer capacitor
JP2014029898A (en) * 2012-07-31 2014-02-13 Taiyo Yuden Co Ltd Electrochemical capacitor

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0665206B2 (en) * 1985-03-07 1994-08-22 松下電器産業株式会社 Electric double layer capacitor
JPH10270293A (en) * 1997-03-26 1998-10-09 Matsushita Electric Ind Co Ltd Electric double layer capacitor
JP2000286161A (en) * 1999-01-26 2000-10-13 Seiko Instruments Inc Electric double-layer capacitor
JP2007201118A (en) * 2006-01-26 2007-08-09 Matsushita Electric Ind Co Ltd Wound electric double-layer capacitor
JP2013175619A (en) * 2012-02-27 2013-09-05 Panasonic Corp Electrolyte used for electric double layer capacitor and electric double layer capacitor
JP2014029898A (en) * 2012-07-31 2014-02-13 Taiyo Yuden Co Ltd Electrochemical capacitor

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