WO2016002564A1 - Cathode for capacitor and method for producing capacitor - Google Patents

Cathode for capacitor and method for producing capacitor Download PDF

Info

Publication number
WO2016002564A1
WO2016002564A1 PCT/JP2015/067889 JP2015067889W WO2016002564A1 WO 2016002564 A1 WO2016002564 A1 WO 2016002564A1 JP 2015067889 W JP2015067889 W JP 2015067889W WO 2016002564 A1 WO2016002564 A1 WO 2016002564A1
Authority
WO
WIPO (PCT)
Prior art keywords
positive electrode
capacitor
negative electrode
current collector
active material
Prior art date
Application number
PCT/JP2015/067889
Other languages
French (fr)
Japanese (ja)
Inventor
知陽 竹山
真嶋　正利
光靖 小川
奥野　一樹
高橋　賢治
光保 上田
Original Assignee
住友電気工業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 住友電気工業株式会社 filed Critical 住友電気工業株式会社
Publication of WO2016002564A1 publication Critical patent/WO2016002564A1/en

Links

Images

Classifications

    • 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
    • H01G11/20—Reformation or processes for removal of impurities, e.g. scavenging
    • 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
    • H01G11/66—Current collectors
    • H01G11/70—Current collectors characterised by their structure
    • 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

Definitions

  • the present invention relates to a positive electrode for a capacitor using a positive electrode active material containing activated carbon and a method for manufacturing the capacitor.
  • a capacitor includes a positive electrode containing activated carbon as a positive electrode active material, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte.
  • a negative electrode including activated carbon is used as a negative electrode active material
  • a negative electrode including a material that absorbs and releases lithium ions is used as a negative electrode active material.
  • Patent Document 1 proposes drying an electrode material containing an electrode active material and a binder.
  • Patent Document 1 a drying process is performed at the electrode material stage in order to reduce the moisture of the electrode.
  • the moisture content of the obtained active material layer is as large as 2900 ppm to 5800 ppm, and it is difficult to sufficiently reduce the moisture content.
  • a current collector containing aluminum is used.
  • the thickness of the positive electrode is larger than when using an aluminum foil, so the water content of the positive electrode is reduced. Becomes even more difficult.
  • the metal porous body has a very large surface area, when the water content of the positive electrode is large, by-products generated by side reactions involving water are deposited on the surface of the metal porous body, and the resistance of the positive electrode is increased.
  • Such an increase in positive electrode resistance is a problem peculiar to a metal porous body containing aluminum, and hardly causes a problem when an aluminum foil having a small surface area is used. Then, it aims at providing the manufacturing method of the positive electrode for capacitors useful for obtaining the capacitor by which the increase in resistance was suppressed, and a capacitor.
  • One aspect of the present invention is a positive electrode for a capacitor comprising a positive electrode current collector and a positive electrode mixture supported on the positive electrode current collector,
  • the positive electrode current collector has a three-dimensional network skeleton containing aluminum or an aluminum alloy,
  • the positive electrode mixture includes at least a positive electrode active material and a binder,
  • the positive electrode active material includes activated carbon,
  • the binder includes a polymer in which at least one of a melting point and a deflection temperature under load according to JIS K7191 is 250 ° C. or higher.
  • the moisture content relates to a positive electrode for a capacitor having 500 ppm or less.
  • Another aspect of the present invention is: Preparing a positive electrode (a), A step (b) of forming an electrode group with the positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and a step (c) of accommodating the electrode group and a non-aqueous electrolyte in a cell case,
  • the step (a) A step (a1) of preparing a positive electrode mixture containing at least a positive electrode active material containing activated carbon, and a binder containing at least one of a melting point and a deflection temperature under load in accordance with JIS K7191 of 250 ° C.
  • the present invention relates to a method for manufacturing a capacitor.
  • FIG. 2 is a partial cross-sectional view schematically showing an internal structure when the capacitor of FIG. 1 is viewed from the front.
  • FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2.
  • a positive electrode for a capacitor according to an embodiment of the present invention includes (1) a positive electrode current collector and a positive electrode mixture supported on the positive electrode current collector.
  • the positive electrode current collector has a three-dimensional network skeleton containing aluminum or an aluminum alloy.
  • the positive electrode mixture includes at least a positive electrode active material and a binder.
  • the positive electrode active material includes activated carbon.
  • the binder includes a polymer in which at least one of a melting point and a deflection temperature under load according to JIS K7191 is 250 ° C. or higher.
  • the water content of the positive electrode is 500 ppm or less.
  • the positive electrode active material containing activated carbon is used for the positive electrode of the capacitor. Since activated carbon has a large specific surface area and high hydrophilicity, a large amount of moisture is easily adsorbed on the activated carbon. Therefore, in the positive electrode containing activated carbon, the moisture content (or residual moisture content) of the positive electrode tends to increase. On the other hand, in an alkali metal ion capacitor such as a lithium ion capacitor and a capacitor such as EDLC, a nonaqueous electrolyte containing a nonaqueous solvent is used as an electrolyte.
  • an alkali metal ion capacitor such as a lithium ion capacitor and a capacitor such as EDLC
  • a nonaqueous electrolyte containing a nonaqueous solvent is used as an electrolyte.
  • the thickness of the positive electrode tends to be large, so that it is difficult to remove moisture compared to the case where a metal foil is used as a current collector.
  • the positive electrode current collector If the amount of water in the positive electrode is large, side reactions involving water tend to occur.
  • a metal porous body having a three-dimensional network skeleton containing aluminum is used as the positive electrode current collector, the surface area of the positive electrode current collector is very large. Therefore, a by-product generated by a side reaction between the electrolyte and water is deposited on the surface of the positive electrode current collector, and the resistance of the positive electrode increases. As the resistance of the positive electrode increases, the rate characteristics of the capacitor decrease.
  • the positive electrode resistance means "positive electrode charge transfer resistance". If a large amount of moisture remains in a capacitor using a non-aqueous electrolyte, hydrogen gas is generated due to electrolysis of water, the internal pressure of the capacitor increases, and a micro short circuit may occur. In addition, an acid is generated due to a side reaction between the electrolyte and water, and the positive electrode current collector containing aluminum may be corroded, resulting in a decrease in capacitor capacity.
  • the water content of the positive electrode is greatly reduced, it is possible to suppress the deposition of by-products on the surface of the positive electrode current collector having a three-dimensional network skeleton containing aluminum. Therefore, an increase in resistance at the positive electrode can be suppressed.
  • By maintaining high conductivity in the positive electrode it is possible to suppress a decrease in the rate characteristics of the capacitor.
  • the side reaction is reduced by using the positive electrode with a reduced amount of moisture, it is possible to suppress a reduction in the capacitor capacity.
  • the moisture content (or residual moisture amount) of the positive electrode means the moisture content (residual moisture amount) of the positive electrode after assembling the electrode group using the positive electrode and before contacting with the nonaqueous electrolyte. To do. More specifically, it may be the moisture content (or residual moisture amount) of the positive electrode in a stage after the electrode group is accommodated in the cell case and before the nonaqueous electrolyte is accommodated in the cell case.
  • the amount of water in the positive electrode is the total amount of water in the positive electrode current collector and the positive electrode mixture supported on the positive electrode current collector.
  • a capacitor is assembled, and after degassing after acclimation charging / discharging, the moisture content in the positive electrode is further reduced.
  • At least one of the melting point and the deflection temperature under load of the polymer contained in the binder is 250 ° C. or higher.
  • the polymer contained in the binder has only one of the melting point and the deflection temperature under load, one of them is 250 ° C. or higher.
  • the polymer contained in the binder has both a melting point and a deflection temperature under load, only one of the melting point and the deflection temperature under load may be 250 ° C or higher, and both are 250 ° C or higher. Also good.
  • at least one of the melting point and the deflection temperature under load of the polymer contained in the binder is 250 ° C.
  • the melting point and the deflection temperature under load are indicators of the heat resistance of the polymer. Further, the deflection temperature under load can be measured in accordance with method A of JIS K7191 (or ISO 75 or ASTM D648). The load at the time of measurement is, for example, 1.80 MPa to 1.82 MPa.
  • the charge transfer resistance of the positive electrode is preferably 2 ⁇ ⁇ cm 2 or less. In such a positive electrode, the effect of improving the rate characteristics of the capacitor is even higher.
  • the polymer is preferably at least one selected from the group consisting of carboxyalkyl cellulose, carboxyalkyl cellulose salt, and polyimide resin.
  • the polymer is preferably at least one selected from the group consisting of carboxymethylcellulose, alkali metal salts of carboxymethylcellulose, polyimide, and polyamideimide.
  • the polyimide resin refers to a resin such as polyimide, polyamideimide, polyetherimide, or polyesterimide.
  • the water content of the positive electrode is preferably 300 ppm or less.
  • the use of the binder as described above and the use of the positive electrode current collector having a three-dimensional network skeleton can suppress the falling off of the positive electrode active material and the positive electrode mixture. Even when charging and discharging are repeated, a high capacitor capacity can be maintained.
  • the positive electrode preferably has a thickness of 500 ⁇ m to 2000 ⁇ m.
  • the amount of the polymer in the binder is 90% by mass to 100% by mass, and the amount of the binder is preferably 10 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. Even if the amount of the binder is as small as this, by using the positive electrode current collector having a three-dimensional network skeleton, it is possible to suppress the falling off of the positive electrode active material and the positive electrode mixture, and even if charging and discharging are repeated. A high capacitor capacity can be maintained.
  • the method for manufacturing a capacitor according to another embodiment of the present invention includes a step (a) of preparing a positive electrode, a step of forming an electrode group with a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. (B) and the process (c) which accommodates an electrode group and a nonaqueous electrolyte in a cell case.
  • Step (a) is a step of preparing a positive electrode mixture containing at least a positive electrode active material containing activated carbon and a binder containing a polymer having a melting point and a deflection temperature under load in accordance with JIS K7191 of 250 ° C. or higher.
  • Step (A1) The step (a2) and the step (a2) of filling the positive electrode mixture with a positive electrode current collector having a three-dimensional network skeleton containing aluminum or an aluminum alloy are compressed in the thickness direction.
  • Step (a3) the compressed product obtained in the step (a3) at a temperature of 200 ° C. or higher so that the moisture content of the positive electrode is 500 ppm or less before the electrode group is in contact with the nonaqueous electrolyte.
  • the “temperature lower than the lower one of the melting point and the deflection temperature under load of the polymer” means a temperature lower than one when the polymer has only one of the melting point and the deflection temperature under load. When a molecule has both a melting point and a deflection temperature under load, the temperature is lower than both.
  • the compressed product is preferably dried under reduced pressure, far infrared rays, or reduced pressure and far infrared rays.
  • the positive electrode is dried by such a drying method, not only the surface of the positive electrode but also the inside thereof is easily dried relatively uniformly. Therefore, an increase in resistance of the positive electrode can be more effectively suppressed.
  • the non-aqueous electrolyte has alkali metal ion conductivity
  • the negative electrode is a negative electrode current collector
  • the negative electrode current collector preferably has a three-dimensional network metal skeleton
  • the negative electrode active material preferably contains a material that reversibly carries alkali metal ions.
  • the capacitor obtained by the manufacturing method according to such an embodiment is referred to as an alkali metal ion capacitor.
  • the negative electrode active material used has high hydrophobicity and easily reduces the moisture content of the negative electrode. Therefore, the amount of moisture in the capacitor can be further reduced, and the effect of suppressing side reactions is further enhanced.
  • the positive electrode includes a positive electrode current collector and a positive electrode mixture supported on the positive electrode current collector, and the positive electrode mixture includes at least a positive electrode active material and a binder.
  • the positive electrode current collector contains aluminum or an aluminum alloy.
  • the content of aluminum in the positive electrode current collector is, for example, 80% by mass or more, preferably 90% by mass or more, and more preferably 95% by mass or more or 98% by mass or more.
  • the content of aluminum in the positive electrode current collector is 100% by mass or less, and may be 99.9% by mass or less. These lower limit values and upper limit values can be arbitrarily combined.
  • the content of aluminum in the positive electrode current collector may be, for example, 80% by mass to 100% by mass, or 95% by mass to 100% by mass.
  • the positive electrode current collector may contain impurities inevitably mixed therein.
  • Examples of the aluminum alloy contained in the positive electrode current collector include an aluminum-iron alloy, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-silicon alloy, an aluminum-magnesium alloy, an aluminum-magnesium-silicon alloy, and an aluminum-zinc alloy. And aluminum-nickel alloy.
  • the positive electrode current collector has a three-dimensional network skeleton containing aluminum or an aluminum alloy.
  • a three-dimensional network skeleton is a skeleton or structure having a fiber part (or rod-like part) formed of aluminum or an aluminum alloy, and the fiber parts are three-dimensionally connected to form a network network.
  • the positive electrode current collector can include a plurality of fiber portions (or rod-shaped portions), and the plurality of fiber portions are three-dimensionally connected to form a three-dimensional network skeleton.
  • the three-dimensional network positive electrode current collector is a resin porous material (resin foam, resin nonwoven fabric, etc.) having continuous voids, for example, a metal constituting the current collector by plating or the like (specifically Can be formed by coating with aluminum and / or an aluminum alloy.
  • Each of the obtained positive electrode current collectors has a large number of cell-like pores corresponding to the shape of the resin foam, and continuous pores (that is, these cell-like pores communicated) (that is, Communication hole). It is preferable that an opening (or window) is formed between the adjacent cellular holes, and the holes communicate with each other.
  • the porosity of the positive electrode current collector is, for example, 30% to 99% by volume, preferably 50% to 98% by volume, and more preferably 80% to 98% by volume or 90%. From volume% to 98 volume%.
  • the average pore diameter in the three-dimensional network skeleton (average diameter of cell-like pores communicating with each other) is, for example, 50 ⁇ m to 1000 ⁇ m from the viewpoint of filling and retaining properties of the positive electrode mixture and easy removal of moisture.
  • the thickness is preferably 100 ⁇ m to 900 ⁇ m, more preferably 350 ⁇ m to 900 ⁇ m.
  • the average pore diameter is preferably smaller than the thickness of the positive electrode current collector (or positive electrode).
  • the three-dimensional network skeleton of the positive electrode current collector has a cavity inside (that is, is hollow).
  • the cavity in the skeleton is formed by removing the porous resin body.
  • the cavity in the skeleton of the positive electrode current collector may have a communication hole shape, and such a skeleton has a tunnel shape or a tube shape.
  • a positive electrode current collector having a hollow skeleton is extremely lightweight while having a bulky three-dimensional structure.
  • the average width of the cavity inside the skeleton is, for example, 0.5 ⁇ m to 5 ⁇ m, preferably 1 ⁇ m to 4 ⁇ m, or 2 ⁇ m to 3 ⁇ m.
  • the positive electrode mixture supported on the positive electrode current collector contains at least a positive electrode active material and a binder.
  • the positive electrode active material includes activated carbon.
  • Activated carbon functions as a positive electrode active material by carrying at least an anion reversibly among the anions and cations contained in the electrolyte of the capacitor.
  • the activated carbon can reversibly carry both anions and cations in the capacitor.
  • Activated carbon can reversibly carry at least an anion by a non-Faraday reaction during charging and discharging.
  • activated carbon can adsorb and desorb at least anions during charging and discharging.
  • the activated carbon known ones used for capacitors can be used.
  • the raw material of activated carbon include wood; coconut shells; pulp waste liquid; coal or coal-based pitch obtained by thermal decomposition thereof; heavy oil or petroleum-based pitch obtained by thermal decomposition thereof; phenol resin and the like.
  • the activated carbon may not be activated, but is preferably activated.
  • the average particle diameter of the activated carbon is not particularly limited, but is preferably 20 ⁇ m or less, and more preferably 3 ⁇ m to 15 ⁇ m.
  • the average particle diameter means a volume-based median diameter in a particle size distribution obtained by laser diffraction particle size distribution measurement.
  • the specific surface area (BET specific surface area) of the activated carbon is not particularly limited, but is preferably 800 m 2 / g to 3000 m 2 / g, and more preferably 1500 m 2 / g to 3000 m 2 / g.
  • the specific surface area is in such a range, it is advantageous for increasing the capacitance of the capacitor, and it is easy to reduce the internal resistance.
  • Activated carbon may be used alone or in combination of two or more different raw materials, average particle diameters and / or specific surface areas.
  • the positive electrode active material may include an active material other than activated carbon (for example, mesoporous carbon, carbon nanotube, etc.).
  • the content of activated carbon in the positive electrode active material is preferably 80% by mass to 100% by mass, and more preferably 90% by mass to 100% by mass. It is also preferable that the positive electrode active material contains only activated carbon.
  • the binder contained in the positive electrode mixture contains a polymer having binding properties.
  • at least one of the melting point of the polymer contained in the binder and the deflection temperature under load in accordance with JIS K7191 is 250 ° C. or higher.
  • Such a polymer has high heat resistance and hardly deteriorates in the manufacturing process of the positive electrode and the capacitor. Therefore, the polymer can be dried at a relatively high temperature.
  • the positive electrode current collector having a three-dimensional network shape is used, it is difficult to remove moisture from the positive electrode.
  • a binder containing such a polymer drying at a higher temperature is possible.
  • the amount of water contained in the positive electrode can be greatly reduced.
  • the positive electrode active material and / or the positive electrode mixture are prevented from falling off, and a high capacitor capacity can be maintained even after repeated charge and discharge.
  • At least one of the melting point and the deflection temperature under load of the polymer is preferably 250 ° C. or higher, and more preferably 270 ° C. or higher. Since at least one of the melting point of the polymer and the deflection temperature under load is such a temperature, it becomes possible to perform drying at a higher temperature in the manufacturing process of the positive electrode and / or capacitor, so that the water content is greatly reduced. it can. At least one of the melting point and the deflection temperature under load of the polymer is, for example, 500 ° C. or less, and preferably 400 ° C. or less. These lower limit values and upper limit values can be arbitrarily combined. For example, a preferable temperature range of at least one of the melting point and the deflection temperature under load of the polymer may be 250 ° C. to 500 ° C., or 270 ° C. to 400 ° C.
  • one of them is preferably 200 ° C or higher or higher than 200 ° C, more preferably 220 ° C or higher or higher than 220 ° C, more preferably 250 ° C. More preferably, it is more preferably 270 ° C. or higher.
  • both are preferably 200 ° C or higher or higher than 200 ° C, more preferably 220 ° C or higher or higher than 220 ° C, and 250 ° C or higher. Is more preferable, and it is especially preferable that it is 270 degreeC or more.
  • the polymer has only one of the melting point and the deflection temperature under load, one of them is, for example, 500 ° C. or less, preferably 400 ° C. or less.
  • the polymer has both a melting point and a deflection temperature under load, both are, for example, 500 ° C. or lower, and preferably 400 ° C. or lower.
  • the polymer needs to have a certain degree of binding properties from the viewpoint of suppressing the removal of the positive electrode active material and / or the positive electrode mixture.
  • the binding property required for the polymer may not be so high, and the binding property required for the binder used in the electrode of the capacitor.
  • the binding property may be such that viscosity can be imparted to the positive electrode mixture (specifically, the positive electrode mixture slurry).
  • Examples of the polymer used for the binder include cellulose ether, polyimide resin (polyimide, polyamideimide, polyetherimide, polyesterimide, etc.), polyamide resin (aromatic polyamide, etc.), and the like.
  • Examples of cellulose ethers include carboxyalkyl celluloses such as carboxymethyl cellulose (CMC); carboxyalkyl cellulose salts such as sodium salt of CMC (alkali metal salts such as sodium salt and potassium salt; ammonium salts); hydroxyethyl cellulose, hydroxy Examples thereof include hydroxyalkylcellulose such as propylmethylcellulose. These polymers can be used singly or in combination of two or more.
  • carboxyalkyl cellulose, its salt, and polyimide resin are preferred from the viewpoint of high heat resistance and excellent function as a binder.
  • carboxy C 1-3 alkyl cellulose such as CMC and salts thereof (such as alkali metal salt of CMC), polyimide, and polyamideimide are preferable.
  • cellulose ethers such as carboxyalkyl cellulose
  • CMC and CMC salts are preferable.
  • the degree of etherification of cellulose ether is an average value of the amount of ether bonds introduced, and can take a value of 0 to 3. From the viewpoint of dispersibility, binding properties and / or ease of water content reduction in the positive electrode mixture, the degree of etherification of the cellulose ether used in the binder is preferably 0.6 to 1.5. More preferably, it is 0.6 to 1.0.
  • the cellulose ether has a certain molecular weight or degree of polymerization.
  • the molecular weight or degree of polymerization of cellulose ether is often evaluated using the viscosity of an aqueous solution containing cellulose ether at a predetermined concentration (for example, a concentration of 1% by mass to 2% by mass) as an index.
  • the cellulose ether used in the binder preferably has a viscosity of an aqueous solution having a concentration of 1% by mass of 10 mPa ⁇ s to 300 mPa ⁇ s at 25 ° C., more preferably 10 mPa ⁇ s to 50 mPa ⁇ s. .
  • the effect which suppresses the increase in resistance in a positive electrode can also be heightened further.
  • the amount of the polymer in the binder is, for example, 80% by mass to 100% by mass, and preferably 90% by mass to 100% by mass. You may comprise a binder only with said polymer
  • the amount of the binder is, for example, 10 parts by mass or less (eg, 0.1 to 10 parts by mass), preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the positive electrode active material. More preferably, it is 1 to 4 parts by mass.
  • the positive electrode mixture can further contain a conductive additive.
  • the type of the conductive aid is not particularly limited, and carbon black such as acetylene black and ketjen black; graphite (natural graphite such as flake graphite and earth graphite; artificial graphite and the like); conductive compound such as ruthenium oxide; Examples thereof include conductive fibers such as carbon fibers and metal fibers.
  • a conductive support agent can be used individually by 1 type or in combination of 2 or more types.
  • the amount of the conductive assistant is, for example, 1 part by mass to 20 parts by mass, or preferably 5 parts by mass to 15 parts by mass with respect to 100 parts by mass of the positive electrode active material.
  • the moisture content of the positive electrode can be greatly reduced despite the use of a positive electrode active material containing activated carbon having high hydrophilicity.
  • the moisture content of the positive electrode is 500 ppm or less, preferably 400 ppm or less, more preferably 300 ppm or less, and still more preferably 200 ppm or less.
  • the moisture content of the positive electrode is desirably as small as possible, but it is difficult to make it 0 ppm. Therefore, the moisture content of the positive electrode may be, for example, more than 0 ppm or 10 ppm or more.
  • the moisture content of the positive electrode exceeds 500 ppm, the side reaction involving water becomes prominent in the capacitor, and the resistance of the positive electrode is greatly increased. For this reason, the rate characteristics of the capacitor are deteriorated. In addition, gas generation becomes significant and the capacitor capacity decreases.
  • the moisture content of the positive electrode can be measured by the Karl Fischer method.
  • the Karl Fischer method is classified into a volumetric titration method and a coulometric titration method.
  • a coulometric titration method with high analysis accuracy is adopted.
  • a commercially available Karl Fischer moisture meter for example, MKC-610 manufactured by Kyoto Denshi Kogyo Co., Ltd.
  • MKC-610 manufactured by Kyoto Denshi Kogyo Co., Ltd.
  • the positive electrode according to the embodiment of the present invention although a positive electrode current collector containing aluminum having a three-dimensional network skeleton is used, it is possible to suppress the accumulation of by-products on the surface of the positive electrode current collector. , The increase in resistance is suppressed.
  • the charge transfer resistance of the positive electrode is preferably 2 ⁇ ⁇ cm 2 or less (specifically, 0 ⁇ ⁇ cm 2 to 2 ⁇ ⁇ cm 2 ), more preferably 1.5 ⁇ ⁇ cm 2 or less. 4 ⁇ ⁇ cm 2 or less is more preferable, and 1.2 ⁇ ⁇ cm 2 or less is particularly preferable.
  • the charge transfer resistance of the positive electrode tends to increase as the cell becomes smaller, for example, in a cell having a capacity of 2 Ah to 4 Ah, the charge transfer resistance of the positive electrode is preferably in the above range.
  • the charge transfer resistance of the positive electrode can be obtained by, for example, an AC impedance method.
  • the thickness of the positive electrode can be selected from the range of 100 ⁇ m to 2000 ⁇ m, for example, preferably 300 ⁇ m to 2000 ⁇ m, more preferably 500 ⁇ m to 2000 ⁇ m. When the thickness of the positive electrode is in such a range, a high capacitor capacity is easily obtained. When the thickness of the positive electrode is large, for example, even when the thickness of the positive electrode is 300 ⁇ m or more or 500 ⁇ m or more, according to the embodiment of the present invention, the moisture content is effectively reduced by using a specific binder. can do.
  • the positive electrode is obtained by preparing a positive electrode mixture, supporting the positive electrode mixture on a positive electrode current collector, and compressing (or rolling) the supported material.
  • a positive electrode mixture is prepared, the positive electrode current collector is filled with the positive electrode mixture, the resulting filler is compressed in the thickness direction, and the moisture content of the positive electrode becomes 500 ppm.
  • the positive electrode can be obtained by drying at a high temperature (for example, 200 ° C. or higher and lower than the lower melting point of the polymer contained in the binder and the deflection temperature under load). Details of the manufacturing method of the positive electrode and the capacitor will be described later.
  • the positive electrode mixture filled in the positive electrode current collector is usually used in the form of a slurry containing the components of the positive electrode mixture (positive electrode active material, binder, conductive additive, etc.).
  • the positive electrode mixture slurry is obtained by dispersing the components of the positive electrode mixture in a dispersion medium.
  • the dispersion medium include water, an organic solvent such as N-methyl-2-pyrrolidone (NMP), or a mixture of water and an organic solvent (water-soluble organic solvent such as ethanol). A solvent or the like is used.
  • the type of dispersion medium can be selected according to the type of binder.
  • a binder containing cellulose ether or the like it is preferable to use water or a mixed solvent of water and an organic solvent as the dispersion medium.
  • an organic solvent is preferably used as the dispersion medium.
  • the dispersion medium is removed by drying in the process of manufacturing the positive electrode (after filling the current collector with the slurry and / or after rolling).
  • the moisture content of the positive electrode tends to be high, but according to the embodiment of the present invention, the moisture content of the positive electrode can be greatly reduced even when using a dispersion medium containing water.
  • the capacitor includes a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte in addition to the positive electrode.
  • a negative electrode a separator interposed between the positive electrode and the negative electrode
  • a nonaqueous electrolyte in addition to the positive electrode.
  • the well-known negative electrode used for a capacitor can be used.
  • the negative electrode includes a negative electrode active material.
  • the negative electrode active material preferably includes a material that reversibly supports cations.
  • a negative electrode active material can be suitably selected according to the kind of capacitor.
  • the negative electrode active material includes a material that reversibly carries cations (specifically, adsorption and desorption), that is, a material that causes a non-Faraday reaction.
  • adsorption and desorption a material that causes a non-Faraday reaction.
  • activated carbon, mesoporous carbon and the like exemplified for the positive electrode active material can be used.
  • activated carbon is often used as the negative electrode active material.
  • a negative electrode active material containing activated carbon it is difficult to reduce the moisture content of the negative electrode, and it is difficult to reduce the moisture content in the capacitor. Therefore, when a negative electrode active material containing activated carbon is used, it is preferable to use a negative electrode with a reduced amount of water in accordance with the case of the positive electrode.
  • the negative electrode active material includes a material that reversibly carries (or occludes and releases) alkali metal ions. Such materials cause a Faraday reaction during charging and discharging.
  • an alkali metal titanium oxide for example, a spinel type such as lithium titanium oxide (lithium titanate or the like) Lithium titanium oxide etc.), sodium titanium oxide (sodium titanate etc.)]
  • silicon oxide silicon alloy
  • tin oxide silicon alloy
  • tin alloy examples of the first carbon material include graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), graphite (carbonaceous materials having a graphite-type crystal structure such as natural graphite and artificial graphite), and the like. it can.
  • a negative electrode active material may be used individually by 1 type, and may be used in combination of 2 or more type.
  • the negative electrode active material preferably has a theoretical capacity of 300 mAh / g or more.
  • the first carbon material is preferable, and graphite and / or hard carbon is particularly preferable.
  • the positive electrode according to the embodiment of the present invention is particularly suitable for an alkali metal ion capacitor using such a negative electrode active material.
  • the negative electrode is not particularly limited as long as it includes the negative electrode active material as described above, and may include a negative electrode mixture containing a negative electrode active material and, as an optional component, a binder and / or a conductive additive.
  • the negative electrode can further include a negative electrode current collector.
  • the negative electrode current collector carries a negative electrode active material or a negative electrode mixture.
  • As a conductive support agent it can select suitably from what was illustrated about the positive electrode.
  • the amount of the conductive additive relative to 100 parts by mass of the negative electrode active material can be appropriately selected from the same range as the amount of the conductive auxiliary relative to 100 parts by mass of the positive electrode active material.
  • the type of the binder is not particularly limited.
  • fluorine resins such as polyvinylidene fluoride (PVDF); polyolefin resins; rubbery polymers such as styrene butadiene rubber can be used.
  • a binder can be used individually by 1 type or in combination of 2 or more types.
  • the amount of the binder is not particularly limited, but can be selected from a range of, for example, about 0.1 to 15 parts by mass per 100 parts by mass of the negative electrode active material, from the viewpoint of easily ensuring high binding properties and capacity. Is 0.5 to 10 parts by mass.
  • the negative electrode current collector may be a metal foil, but is preferably a metal porous body from the viewpoint of increasing the capacity of the capacitor.
  • the metal porous body those having the same three-dimensional network skeleton as the positive electrode current collector (particularly, a hollow skeleton) are preferable.
  • the porosity, average pore diameter, void width inside the skeleton, specific surface area, and the like of the metal porous body can be appropriately selected from the ranges exemplified for the positive electrode current collector.
  • the material of the negative electrode current collector is preferably copper, copper alloy, nickel, nickel alloy, stainless steel, or the like.
  • the negative electrode current collector can be produced according to the case of the positive electrode current collector using these materials instead of aluminum or aluminum alloy when the resin porous body is metal-coated.
  • the negative electrode can be formed, for example, by supporting at least a negative electrode active material on a negative electrode current collector.
  • the negative electrode can also be formed by applying or filling a negative electrode mixture containing a negative electrode active material and compressing (or rolling). You may perform a drying process in a suitable stage (after apply
  • the negative electrode one obtained by forming a deposited film of a negative electrode active material on the surface of the negative electrode current collector by a vapor phase method such as vapor deposition or sputtering may be used.
  • the negative electrode mixture is usually used in the form of a slurry containing the constituent components of the negative electrode mixture. The slurry is obtained by dispersing the constituent components of the negative electrode mixture in a dispersion medium. As a dispersion medium, it can select suitably from what was illustrated about the positive electrode.
  • alkali metal ions such as lithium ions and sodium ions are supported (pre-doped) on the negative electrode active material.
  • the pre-doping of alkali metal ions can be performed by a known method.
  • the alkali metal ion pre-doping may be performed before the assembly of the capacitor, or may be performed in the capacitor.
  • the negative electrode used for an alkali metal ion capacitor since the active material is highly hydrophobic, even when a negative electrode mixture that easily mixes moisture is used, the negative electrode current collector is loaded before compressing the support. In addition, the moisture content of the negative electrode can be greatly reduced at the stage of drying after compression. Further, in both the EDLC and the alkali metal ion capacitor, as in the case of the positive electrode, the moisture content of the negative electrode can be further reduced when the capacitor is manufactured.
  • the moisture content of the capacitor other than the positive electrode is as low as possible.
  • the moisture content of the negative electrode can be selected from the same range as the moisture content of the positive electrode, for example, and may be 300 ppm or less or 100 ppm or less.
  • the moisture content of the negative electrode is the moisture content of the negative electrode before being brought into contact with the non-aqueous electrolyte, similarly to the moisture content of the positive electrode, and can be measured by the Karl Fischer method according to the case of the moisture content of the positive electrode.
  • the thickness of the negative electrode can be appropriately selected from the range of 50 ⁇ m to 2000 ⁇ m, for example.
  • the thickness of the negative electrode is, for example, 100 ⁇ m to 2000 ⁇ m, preferably 150 ⁇ m to 2000 ⁇ m.
  • the separator included in the capacitor can be appropriately selected according to the type of the capacitor.
  • the separator has ion permeability, is interposed between the positive electrode and the negative electrode, and physically separates them to prevent a short circuit.
  • the separator has a porous structure and allows ions to pass through by holding an electrolyte in the pores.
  • a material of the separator for example, polyolefin such as polyethylene and polypropylene; polyester such as polyethylene terephthalate; polyamide; polyimide; cellulose; glass fiber and the like can be used.
  • the average pore diameter of the separator is not particularly limited and is, for example, about 0.01 ⁇ m to 5 ⁇ m.
  • the thickness of the separator is not particularly limited and is, for example, about 10 ⁇ m to 100 ⁇ m.
  • the separator is preferably dried when assembling the electrode group to reduce the amount of water.
  • the moisture content of the separator is preferably 400 ppm or less, and more preferably 250 ppm or less, before the electrode group is formed.
  • the moisture content of this separator is the moisture content of the separator before contacting with the non-aqueous electrolyte as in the case of the positive electrode, and can be measured by the Karl Fischer method according to the case of the positive electrode.
  • the nonaqueous electrolyte can be selected according to the type of capacitor.
  • the non-aqueous electrolyte includes a cation and an anion.
  • the non-aqueous electrolyte is preferably reduced in water content before being injected into the capacitor.
  • the water content of the non-aqueous electrolyte can be reduced by dehydrating a medium (specifically, an organic solvent and an ionic liquid described later) and / or a solute (such as an alkali metal salt) as a raw material.
  • a medium specifically, an organic solvent and an ionic liquid described later
  • a solute such as an alkali metal salt
  • the dehydration of the medium and the solute can be performed by a known method.
  • the moisture content can be further reduced when the capacitor is manufactured.
  • the water content of the nonaqueous electrolyte is, for example, preferably 200 ppm or less, and more preferably 100 ppm or less or 50 ppm or less.
  • the water content of the non-aqueous electrolyte is before the non-aqueous electrolyte is accommodated in the cell case, and can be measured by the Karl Fischer method according to the case of the positive electrode.
  • Nonaqueous electrolyte for alkali metal ion capacitors In the alkali metal ion capacitor, a non-aqueous electrolyte having alkali metal ion conductivity is used. Such a non-aqueous electrolyte contains a cation containing an alkali metal ion and an anion.
  • Nonaqueous electrolytes include, for example, an electrolyte (organic electrolyte) in which a salt of an alkali metal ion and an anion (alkali metal salt) is dissolved in a nonaqueous solvent (or an organic solvent), and a cation and an anion containing an alkali metal ion.
  • An ionic liquid containing or the like is used.
  • the organic electrolyte can contain an ionic liquid and / or an additive in addition to the non-aqueous solvent (organic solvent) and the alkali metal salt.
  • the total content of the nonaqueous solvent and the lithium salt in the electrolyte is, for example, 60% by mass to 100% by mass, preferably 75% by mass to 100% by mass, or 85% by mass to 100% by mass.
  • the total content of the nonaqueous solvent and the lithium salt in the electrolyte may be, for example, 95% by mass or less.
  • an ionic liquid is synonymous with a salt (molten salt) in a molten state, and is a liquid ionic substance composed of an anion and a cation.
  • the electrolyte can contain a nonaqueous solvent and / or an additive in addition to the ionic liquid containing a cation containing an alkali metal ion and an anion.
  • the content of the ionic liquid in the electrolyte is preferably 60% by mass to 100% by mass, and may be 80% by mass to 100% by mass or 90% by mass to 100% by mass.
  • an electrolyte containing an organic solvent From the viewpoint of low temperature characteristics and the like, it is preferable to use an electrolyte containing an organic solvent. From the viewpoint of suppressing the decomposition of the electrolyte as much as possible, an electrolyte containing an ionic liquid is preferably used, and an electrolyte containing an ionic liquid and an organic solvent may be used.
  • the concentration of the alkali metal salt or alkali metal ion in the electrolyte can be appropriately selected from the range of 0.3 mol / L to 5 mol / L, for example.
  • alkali metal ions examples include at least one selected from the group consisting of lithium ions, sodium ions, potassium ions, rubidium ions, and cesium ions. Of these, at least one selected from the group consisting of lithium ions and sodium ions is preferred.
  • the alkali metal ions can be smoothly occluded in the negative electrode active material during charging, and can be released from the negative electrode active material during discharge.
  • An alkali metal ion capacitor using an electrolyte having lithium ion conductivity is also referred to as a lithium ion capacitor.
  • An alkali metal ion capacitor using an electrolyte having sodium ion conductivity is also referred to as a sodium ion capacitor.
  • the kind of anion (first anion) constituting the alkali metal salt is not particularly limited.
  • an anion of a fluorine-containing acid anion of fluorine-containing phosphate such as hexafluorophosphate ion; fluorine such as tetrafluoroborate ion; Oxides such as anions of boric acid containing], anions of chlorine containing acids [such as perchlorate ions], anions of oxygen acids having oxalate groups [bis (oxalato) borate ions (B (C 2 O 4 ) 2 ⁇ )] Latoborate ion; Oxalatophosphate ion such as tris (oxalato) phosphate ion (P (C 2 O 4 ) 3 ⁇ ), anion of fluoroalkanesulfonic acid [trifluoromethanesulfonic acid ion (CF 3 SO 3 ⁇ ), etc. ], Bissulfonylamide anion, etc.
  • bissulfonylamide anion examples include bis (fluorosulfonyl) amide anion (FSA ⁇ : bis (fluorosulfonyl) amide anion), bis (trifluoromethylsulfonyl) amide anion (TFSA ⁇ : bis (trifluoromethylsulfamide) amide anion.
  • the non-aqueous solvent is not particularly limited, and a known non-aqueous solvent used for a lithium ion capacitor can be used.
  • Non-aqueous solvents include, for example, cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; cyclic carbonates such as ⁇ -butyrolactone. Etc. can be preferably used.
  • a non-aqueous solvent may be used individually by 1 type, and may be used in combination of 2 or more type.
  • the ionic liquid contains a molten salt of a cation and an anion (second anion).
  • the ionic liquid may contain a kind of molten salt, or may contain two or more kinds of molten salts having different types of cations and / or second anions.
  • a bissulfonylamide anion is preferably used as the second anion.
  • the bissulfonylamide anion can be selected from those similar to those exemplified for the first anion.
  • the cation constituting the ionic liquid contains at least an alkali metal ion, and may contain an alkali metal ion (first cation) and a second cation.
  • the second cation include an inorganic cation and an organic cation different from the alkali metal ion.
  • the inorganic cation include alkaline earth metal ions (magnesium ions, calcium ions, etc.), ammonium ions, and the like.
  • the second cation may be an inorganic cation, but is preferably an organic cation.
  • the ionic liquid may contain one type of second cation, or may contain two or more types in combination.
  • Organic cations include cations derived from aliphatic amines, alicyclic amines or aromatic amines (for example, quaternary ammonium cations), as well as cations having nitrogen-containing heterocycles (that is, derived from cyclic amines). Examples thereof include nitrogen-containing onium cations such as cations); sulfur-containing onium cations; and phosphorus-containing onium cations. Of the nitrogen-containing organic onium cations, those having a pyrrolidine, pyridine, or imidazole skeleton as the nitrogen-containing heterocyclic skeleton in addition to the quaternary ammonium cation are particularly preferable.
  • nitrogen-containing organic onium cations include tetraalkylammonium cations (TEA + : tetraethylammonium cation), tetraalkylammonium cations such as methyltriethylammonium cation (TEMA + : methyltriethylammonium cation); 1-methyl-1-propylpyrrolidinium Cations (MPPY + : 1-methyl-1-propylpyrrolidinium cation), 1-butyl-1-methylpyrrolidinium cation (MBPY + : 1-butyl-1-methylpyrrolidinium cation); 1-ethyl-3-methylimidazolium cation (EMI +: 1-ethyl- 3-methylimidazo ium cation), 1- butyl-3-methylimidazolium cation (BMI +: 1-buthyl- 3-methylimidazolium cation) and the like.
  • TEA + te
  • Nonaqueous electrolytes used in EDLC include electrolytes in which a salt of a cation (third cation) and an anion (third anion) is dissolved in a nonaqueous solvent (or organic solvent), as well as a cation (fourth cation). And a non-aqueous electrolyte such as an ionic liquid containing an anion (fourth anion) is preferably used.
  • Examples of the third and fourth cations include inorganic cations (alkali metal ions, alkaline earth metal ions, ammonium ions, etc.) and organic cations exemplified for the non-aqueous electrolyte of the alkali metal ion capacitor.
  • concentration of the cation in the electrolyte can be appropriately selected from a range of 0.3 mol / L to 5 mol / L, for example.
  • the third anion can be appropriately selected from those exemplified as the first anion of the alkali metal ion capacitor. As a nonaqueous solvent, it can select suitably from what was illustrated about the alkali metal ion capacitor.
  • the fourth anion contained in the ionic liquid can be appropriately selected from those exemplified as the second anion of the alkali metal ion capacitor.
  • the fourth anion preferably includes at least a bissulfonylamide anion. The content of the bissulfonylamide anion in the fourth anion can be selected from the same range as in the case of the second anion.
  • the content of the ionic liquid in the electrolyte can be appropriately selected from the range exemplified for the alkali metal ion capacitor.
  • an electrolyte containing an ionic liquid is preferably used, and an electrolyte containing an ionic liquid and an organic solvent may be used.
  • a capacitor according to an embodiment of the present invention includes (a) a step of preparing a positive electrode, (b) a step of forming an electrode group with a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and (c) It can manufacture by passing through the process of accommodating an electrode group and a nonaqueous electrolyte in a cell case. After the step (c), an activation step (d) may be further performed. When the activation step (d) is performed, the amount of moisture in the capacitor can be further reduced.
  • step (a) the step (a1) for preparing the positive electrode mixture, the step (a2) for filling the positive electrode current collector with the positive electrode mixture, and the packing obtained in the step (a2) are compressed in the thickness direction (or Rolling) and a step (a4) of drying the compressed product obtained in the step (a3).
  • the step (a) may be performed in a dry atmosphere, and the step (a1), the step (a2) and / or the step (a3) may be performed in a dry atmosphere.
  • a material (component of the positive electrode mixture) used in the step (a1) it is preferable to use a dried material.
  • step (a3) the packing obtained in step (a2) may be dried (preliminarily dried) prior to compression.
  • the preliminary drying may be performed in an air atmosphere or under reduced pressure.
  • the temperature of the preliminary drying is not particularly limited, but may be, for example, 60 ° C. to 150 ° C. or 80 ° C. to 120 ° C.
  • the drying time for the preliminary drying is not particularly limited, and may be, for example, 0.5 to 6 hours or 0.5 to 3 hours.
  • Compressing in the step (a3) may be performed in a dry atmosphere so that the moisture content of the positive electrode does not increase before contacting with the non-aqueous electrolyte.
  • the compression may be performed, for example, in an atmosphere having a dew point temperature of ⁇ 50 ° C. or lower or ⁇ 60 ° C. or lower.
  • step (a4) the amount of water in the positive electrode is reduced by drying the compressed product obtained in step (a3) at a high temperature.
  • the drying temperature in the step (a4) is 200 ° C. or higher, and may be 220 ° C. or higher. By drying at such a temperature, the amount of water in the positive electrode after assembling the electrode group and before contacting with the non-aqueous electrolyte can be reduced to the above range.
  • the drying temperature is preferably lower than the lower one of the melting point and the deflection temperature under load of the polymer contained in the binder.
  • the drying in the step (a4) can be performed using hot air drying and / or far infrared drying.
  • drying may be performed under normal pressure or under reduced pressure.
  • a plurality of drying methods can be appropriately combined.
  • drying may be performed using far infrared rays under reduced pressure.
  • the drying in the step (a4) may be performed under reduced pressure, far infrared rays, or reduced pressure and far infrared rays.
  • the drying time in step (a4) is, for example, 3 hours to 48 hours, and may be 6 hours to 24 hours or 8 hours to 16 hours.
  • the electrode group may be formed by laminating the positive electrode and the negative electrode via a separator, or may be formed by winding the positive electrode and the negative electrode via a separator.
  • a well-known method can be employ
  • the capacitor assembled in step (c) is usually subjected to an activation treatment step (d).
  • the capacitor In the activation treatment step (d), the capacitor is subjected to aging treatment (or heat treatment), and charged and discharged in order to enable stable charge and discharge.
  • aging treatment or heat treatment
  • step (d) degassing treatment is performed.
  • the aging treatment is performed after pre-doping.
  • Step (d) can include a pre-doping step, an aging treatment step, a break-in charge / discharge step, and a degassing step.
  • the deposition of by-products on the positive electrode current collector is particularly noticeable when performing an aging treatment. Therefore, in order to suppress the accumulation of by-products, it is preferable to sufficiently reduce the moisture content of the positive electrode in the stage before step (c). According to the embodiment of the present invention, by the step (a4), by reducing the moisture content of the positive electrode used for assembling the capacitor to the above range, it is possible to suppress the accumulation of by-products during the aging process.
  • the aging treatment is preferably performed at, for example, 10 ° C. to 60 ° C., more preferably 20 ° C. to 40 ° C.
  • the degassing process can be performed by discharging the gas generated in the capacitor out of the capacitor from a valve (a degassing valve, a safety valve described later) provided in the capacitor case.
  • FIG. 1 is a perspective view showing an external appearance of a capacitor (lithium ion capacitor) obtained by a manufacturing method according to an embodiment of the present invention.
  • FIG. 2 is a partial cross-sectional view showing the internal structure when the capacitor of FIG. 1 is viewed from the front.
  • 3 is a cross-sectional view taken along line III-III in FIG. 2, showing a part of the internal structure of the capacitor in FIG.
  • the capacitor (lithium ion capacitor) 10 includes an electrode group 12, a non-aqueous electrolyte (not shown), and a cell case that houses them.
  • the cell case includes a case body 14 and a sealing plate 16 that seals the open end of the case body 14.
  • the cell case has a square shape.
  • the electrode group 12 includes a plurality of sheet-like positive electrodes 18 and a plurality of sheet-like negative electrodes 20.
  • the positive electrode 18 and the negative electrode 20 are alternately stacked with the separator 21 interposed therebetween.
  • the separator 21 is formed in a bag shape so as to accommodate the positive electrode 18 therein, but the shape of the separator is not particularly limited.
  • the positive electrode 18 includes a positive electrode current collector 22 and a positive electrode active material.
  • the negative electrode 20 includes a negative electrode current collector 24 and a negative electrode active material. In FIG. 3, it is difficult to distinguish between the electrode and the current collector, and therefore, the electrode and the current collector are indicated by the same element.
  • the sealing plate 16 has a positive external terminal 40 electrically connected to the plurality of positive electrodes 18 and a negative external terminal 42 electrically connected to the plurality of negative electrodes 20.
  • a safety valve 44 is provided at the center of the sealing plate 16. Further, a liquid stopper 48 that closes the liquid injection hole is attached to the sealing plate 16 at a position near the positive electrode external terminal 40 with the safety valve 44 as the center.
  • the positive electrode current collector 22 has a tab-shaped positive electrode connection portion 26, and the negative electrode current collector 24 has a tab-shaped negative electrode connection portion 28.
  • the positive electrode connection portion 26 is formed at a position near the positive electrode external terminal 40
  • the negative electrode connection portion 28 is formed at a position near the negative electrode external terminal 42.
  • Each connecting portion is preferably made of the same material as the current collector and formed integrally with the current collector.
  • a first conductive spacer 30 is disposed between the adjacent positive electrode connection portions 26.
  • a second conductive spacer is disposed between adjacent negative electrode connection portions 28.
  • the first conductive spacer 30 and the second conductive spacer can each be formed of a plate-like member including a conductor (for example, a metal or a carbon material).
  • the first conductive spacer 30 is preferably formed of a metal porous body in order to improve the adhesion with the positive electrode connection portion 26, and in particular, the same material as the positive electrode current collector 22 (for example, aluminum or aluminum alloy).
  • the second conductive spacer is also preferably formed of a metal porous body as in the case of the first conductive spacer 30, and in particular, the same material as the negative electrode current collector 24 (for example, tertiary including copper or copper alloy). It is preferably formed of a metal porous body having an original network-like skeleton.
  • the positive electrode connection portion 26 of the positive electrode 18 is provided with a through hole 36 for inserting a first fastening member (rivet) 34.
  • the first conductive spacer 30 is also provided with a through hole 37 for inserting the first fastening member 34 at a position overlapping the through hole 36 of the positive electrode connecting portion 26.
  • the negative electrode connecting portion 28 of the negative electrode 20 is provided with a through hole for inserting the second fastening member (rivet).
  • the second conductive spacer is also provided with a through hole for inserting the second fastening member at a position overlapping the through hole of the negative electrode connecting portion 28.
  • two through holes are provided, but the number of through holes is not particularly limited.
  • the through holes 36 are aligned in a straight line.
  • the first conductive spacers 30 are also arranged so that the through holes 37 are aligned with the corresponding through holes 36.
  • the first fastening member 34 is formed of the same conductive material as that of the positive electrode current collector 22 in terms of obtaining high corrosion resistance.
  • the second fastening member is preferably formed of the same conductive material as that of the second current collector 24.
  • the positive electrode 18 and the positive external terminal 40 are electrically connected through a positive electrode lead 62.
  • the negative electrode 20 and the negative external terminal 42 are electrically connected via a negative electrode lead.
  • the positive electrode lead 62 in the illustrated example is a member having an L-shaped cross section, and has a plate-like first portion 62a and a second portion 62b that are perpendicular to each other.
  • the positive electrode lead 62 is disposed so that the first portion 62 a is parallel to the sealing plate 16 and the second portion 62 b is perpendicular to the sealing plate 16.
  • the positive electrode lead 62 is electrically connected to the positive electrode 18 mainly when the second portion 62 b comes into contact with the positive electrode connecting portion 26.
  • the second portion 62 b has one or more through holes for inserting the first fastening member 34.
  • the first fastening member 34 inserted through the through hole, the second portion 62b is fixed in contact with the positive electrode connection portion 26, whereby the positive electrode lead 62 is fixed to the positive electrode connection portions 26 of the plurality of positive electrodes 18.
  • the negative electrode lead also has the same shape as the positive electrode lead 62, and is solidified in the negative electrode connection portion 28 and electrically connected to the negative electrode 20 in the same manner as the positive electrode lead 62.
  • the electrode group 12 is configured by laminating the positive electrode 18 and the negative electrode 20 with the separator 21 interposed therebetween. And the comprised electrode group 12 is accommodated in a cell case. Thereafter, a step of injecting a nonaqueous electrolyte into the cell case and impregnating the electrolyte into the gaps of the separator 21, the positive electrode 18, and the negative electrode 20 constituting the electrode group 12 is performed.
  • the moisture content of the positive electrode can be measured before the nonaqueous electrolyte injection step, and may be measured for the electrode group 12 before being accommodated in the cell case.
  • a positive electrode for a capacitor comprising a positive electrode current collector and a positive electrode mixture supported on the positive electrode current collector,
  • the positive electrode current collector has a three-dimensional network skeleton containing aluminum or an aluminum alloy
  • the positive electrode mixture includes at least a positive electrode active material and a binder
  • the positive electrode active material includes activated carbon
  • the binder includes a polymer having binding properties, At least one of a melting point of the polymer and a deflection temperature under load in accordance with JIS K7191 is 250 ° C. or higher, Capacitor positive electrode having a moisture content of 500 ppm or less.
  • the thickness is 500 ⁇ m to 2000 ⁇ m, The charge transfer resistance is 1.5 ⁇ ⁇ cm 2 or less, The amount of water is 300 ppm or less,
  • a lithium ion capacitor A1 was produced according to the following procedure.
  • the foam having a conductive layer formed on the surface was immersed in a molten salt aluminum plating bath, and a direct current having a current density of 3.6 A / dm 2 was applied for 90 minutes to form an aluminum layer.
  • the mass of the aluminum layer per apparent area of the foam was 150 g / m 2 .
  • the molten salt aluminum plating bath contained 33 mol% 1-ethyl-3-methylimidazolium chloride and 67 mol% aluminum chloride, and the temperature was 40 ° C.
  • the foam with the aluminum layer formed on the surface was immersed in a lithium chloride-potassium chloride eutectic molten salt at 500 ° C., and a negative potential of ⁇ 1 V was applied for 30 minutes to decompose the foam.
  • the obtained aluminum porous body was taken out from the molten salt, cooled, washed with water, and dried to obtain a positive electrode current collector.
  • the obtained positive electrode current collector has a three-dimensional network-like porous structure in which pores communicate, reflecting the pore shape of the foam, has a porosity of 94% by volume, and an average pore diameter of 550 ⁇ m.
  • the BET specific surface area was 350 cm 2 / g, and the thickness was 1100 ⁇ m.
  • the three-dimensional mesh-like aluminum skeleton had a communication hole-like cavity formed by removing the foam. In this way, a positive electrode current collector was obtained.
  • the melting point of the CMC Na salt is 290 ° C., and the CMC Na salt does not have a deflection temperature under load. Further, the binder is composed only of Na salt of CMC (the amount of polymer in the binder is 100% by mass).
  • the obtained positive electrode mixture slurry is filled in the current collector obtained in the above step (a), and the filling is pre-dried at 100 ° C. for 60 minutes in an air atmosphere.
  • the film was compressed in the thickness direction using a pair of rolls at a dew point temperature of ⁇ 65 ° C.
  • the obtained compressed product was dried at 220 ° C. for 12 hours under reduced pressure (about 0.1 Pa) to produce a positive electrode having a thickness of 800 ⁇ m.
  • a Cu film having a basis weight of 5 g / cm 2 is formed on the surface of the same thermosetting polyurethane foam as used in the production of the positive electrode current collector ( Conductive layer) was formed.
  • a foam having a conductive layer formed on the surface was used as a work, immersed in a copper sulfate plating bath, and a direct current having a cathode current density of 2 A / dm 2 was applied to form a Cu layer on the surface.
  • the copper sulfate plating bath contained 250 g / L copper sulfate, 50 g / L sulfuric acid, and 30 g / L copper chloride, and the temperature was 30 ° C.
  • the foam with the Cu layer formed on the surface is heat-treated at 700 ° C. in an air atmosphere to decompose the foam, and then fired in a hydrogen atmosphere to reduce the oxide film formed on the surface.
  • a copper porous body (negative electrode current collector) was obtained.
  • the obtained negative electrode current collector has a three-dimensional network-like porous structure in which pores communicate, reflecting the pore shape of the foam, has a porosity of 92% by volume, and an average pore diameter of 550 ⁇ m.
  • the BET specific surface area was 200 cm 2 / g.
  • the three-dimensional network copper skeleton had a communication hole-like cavity formed by removing the foam.
  • a negative electrode mixture slurry was prepared by mixing artificial graphite powder as a negative electrode active material, acetylene black as a conductive additive, PVDF as a binder, and NMP as a dispersion medium. .
  • the mass ratio of the graphite powder, acetylene black, and PVDF was 87: 8: 5.
  • the obtained negative electrode mixture slurry was filled in the current collector obtained in the above step (a), and the filler was pre-dried at 100 ° C. for 60 minutes in the air atmosphere.
  • the dried product was compressed in the thickness direction using a pair of rolls in a dry atmosphere.
  • the compressed product was vacuum-dried at 120 ° C. for 12 hours to prepare a negative electrode having a thickness of 240 ⁇ m.
  • the water content of the obtained negative electrode was 60 ppm.
  • steps (1) and (2) the filling amounts of the positive electrode mixture and the negative electrode mixture were adjusted so that the chargeable capacity of the negative electrode after pre-doping was about twice the capacity of the positive electrode.
  • a lithium foil (thickness: 50 ⁇ m) is pressure-bonded to one surface of a punching copper foil (thickness: 20 ⁇ m, opening diameter: 50 ⁇ m, opening ratio 50%, 2 cm ⁇ 2 cm) as a current collector.
  • a lithium electrode was produced.
  • a nickel lead was welded to the other surface of the current collector of the lithium electrode.
  • the lithium electrode was produced in a dry atmosphere (temperature 25 ° C., dew point ⁇ 50 ° C. or lower).
  • the positive electrode obtained in (1) was cut into a predetermined size, and a positive electrode current collector exposed portion (tab) having a size of 1 cm ⁇ 4 cm was formed at the end.
  • the negative electrode obtained in (2) above was cut into a predetermined size, and a negative electrode current collector exposed portion (tab) having a size of 1 cm ⁇ 4 cm was formed at the end.
  • the size of the positive electrode was 8.5 cm ⁇ 10 cm excluding the tab, and the size of the negative electrode was 8.5 cm ⁇ 10.5 cm excluding the tab.
  • the lead made of aluminum was welded to the exposed portion of the positive electrode current collector, and the lead made of nickel was welded to the exposed portion of the negative electrode current collector.
  • a single cell electrode group was formed by laminating the positive electrode and the negative electrode with a dried cellulose separator (thickness: 60 ⁇ m) interposed between the positive electrode and the negative electrode.
  • the electrode group was formed in an atmosphere having a dew point temperature of about ⁇ 65 ° C. Further, a lithium electrode was arranged on the negative electrode side of the electrode group with the same separator as above, and the obtained laminate was accommodated in a cell case made of an aluminum laminate sheet.
  • the moisture content of the separator was measured by the Karl Fischer method, it was 200 ppm at the stage before the electrode group was formed.
  • a nonaqueous electrolyte was injected into the cell case, and impregnated into the positive electrode, the negative electrode, and the separator.
  • a solution in which LiPF 6 as a lithium salt was dissolved to a concentration of 1.0 mol / L in a mixed solvent containing ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1 was used as the non-aqueous electrolyte.
  • the amount of water in the nonaqueous electrolyte used was 50 ppm.
  • the cell case was sealed while reducing the pressure with a vacuum sealer.
  • the negative electrode lead wire and the lithium electrode lead wire were connected to a power source outside the cell case.
  • the cell in this state was allowed to stand for a predetermined time in a thermostat at 30 ° C. so that the temperature of the electrolyte was the same as the temperature of the thermostat.
  • the negative electrode active material was predoped with lithium. After pre-doping, the cell was aged by heating at 30 ° C. for 12 hours.
  • (C) Charge transfer resistance of positive electrode The charge transfer resistance of the positive electrode was measured by the AC impedance method under the conditions of a voltage amplitude of 5 mV and a frequency range of 0.01 Hz to 10 kHz. Specifically, the charge transfer resistance was determined based on the Nyquist diagram obtained by AC impedance measurement.
  • Examples 2 and 3> A positive electrode was produced in the same manner as in Example 1 except that the time for drying the compressed material was adjusted in (1) and (b) of Example 1 so that the moisture content of the positive electrode was the value shown in Table 1. . Except for using the obtained positive electrode, lithium ion capacitors A2 and A3 were prepared and evaluated in the same manner as in Example 1.
  • Example 1 A positive electrode was produced in the same manner as in Example 1 except that the time for drying the compressed material was adjusted in (1) and (b) of Example 1 so that the moisture content of the positive electrode was the value shown in Table 1. . Except for using the obtained positive electrode, lithium ion capacitors B1 to B3 were prepared and evaluated in the same manner as in Example 1.
  • Example 1 (1) and (b) in place of CMC Na salt, PVDF was used as a binder, and the temperature at which the compressed product was dried was changed to 120 ° C. As in Example 1, the positive electrode Was made. A lithium ion capacitor B4 was produced and evaluated in the same manner as in Example 1 except that the obtained positive electrode was used.
  • Table 1 shows the evaluation results of the examples (lithium ion capacitors A1 to A3) and the comparative examples (lithium ion capacitors B1 to B4).
  • the positive electrode resistance (positive electrode charge transfer resistance) and cell resistance were high, and the rate characteristics were low.
  • the resistance of the positive electrode charge transfer resistance of the positive electrode
  • the cell resistance was remarkably reduced, and the rate characteristics were greatly improved. This is presumably because the use of the positive electrode with a reduced amount of moisture suppressed side reactions and reduced the accumulation of by-products on the surface of the positive electrode current collector.
  • the positive electrode resistance (positive electrode charge transfer resistance) is particularly small, and the rate characteristics are particularly excellent.
  • the drying temperature of the positive electrode could not be raised to the melting point of PVDF or more, and sufficient drying could not be performed. Therefore, it is considered that the resistance of the positive electrode is increased because the amount of water in the positive electrode is large and by-products are deposited on the surface of the positive electrode current collector.
  • the melting point of PVDF is 170 ° C.
  • the deflection temperature under load of PVDF is 156 ° C.
  • the positive electrode for a capacitor and the capacitor according to one embodiment of the present invention an increase in the resistance of the positive electrode is suppressed, and an excellent rate characteristic is obtained. Therefore, it can be applied to various uses that require a high rate.
  • Negative electrode connection portion 30 first conductive spacer, 34: first fastening member, 36, 37: through hole 40: positive electrode external terminal, 42: negative electrode external terminal, 44: safety valve, 48: liquid stopper 62: positive electrode lead, 62a : First part, 62b: Second part

Abstract

A capacitor cathode including a cathode collector and a cathode mixture supported by the cathode collector, wherein the cathode collector has a 3D network shaped skeleton containing aluminum or an aluminum alloy, the cathode mixture contains at least a cathode active material and a binder, the cathode active material contains activated charcoal, the binder contains a polymer of which the melting point and/or the deflection temperature under load conforming to JIS K7191 is at least 250°C, and the moisture content is no greater than 500 ppm.

Description

キャパシタ用正極およびキャパシタの製造方法Capacitor positive electrode and capacitor manufacturing method
　本発明は、活性炭を含む正極活物質を用いたキャパシタ用正極およびキャパシタの製造方法に関する。 The present invention relates to a positive electrode for a capacitor using a positive electrode active material containing activated carbon and a method for manufacturing the capacitor.
　環境問題がクローズアップされる中、太陽光または風力などのクリーンエネルギーを電力に変換し、電気エネルギーとして蓄電するシステムの開発が盛んに行われている。このような蓄電デバイスとしては、リチウムイオン二次電池、電気二重層キャパシタ（ＥＤＬＣ：ｅｌｅｃｔｒｉｃ　ｄｏｕｂｌｅ－ｌａｙｅｒ　ｃａｐａｃｉｔｏｒ）、リチウムイオンキャパシタなどが知られている。最近では、瞬時の充放電特性に優れるとともに、高い出力特性が得られ、取り扱い性に優れるといった観点から、ＥＤＬＣ、リチウムイオンキャパシタなどのキャパシタが注目されている。 中 Amid the close-up of environmental issues, systems that convert clean energy such as solar or wind power into electric power and store it as electric energy are being actively developed. As such an electricity storage device, a lithium ion secondary battery, an electric double-layer capacitor (EDLC), a lithium ion capacitor, and the like are known. Recently, capacitors such as EDLCs and lithium ion capacitors have attracted attention from the viewpoints of excellent instantaneous charge / discharge characteristics, high output characteristics, and excellent handleability.
　一般に、キャパシタは、正極活物質として活性炭を含む正極と、負極と、正極および負極間に介在するセパレータと、電解質とを含む。ＥＤＬＣでは、負極活物質として活性炭を含む負極が用いられ、リチウムイオンキャパシタでは、負極活物質としてリチウムイオンを吸蔵および放出する材料を含む負極が用いられている。 Generally, a capacitor includes a positive electrode containing activated carbon as a positive electrode active material, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. In EDLC, a negative electrode including activated carbon is used as a negative electrode active material, and in a lithium ion capacitor, a negative electrode including a material that absorbs and releases lithium ions is used as a negative electrode active material.
　非水溶媒を含む電解質（いわゆる非水電解質）を用いるキャパシタでは、水分の混入がキャパシタ特性に影響する場合がある。そのため、キャパシタ内の水分量を低減することが検討されている。例えば、特許文献１では、電極活物質および結着剤を含む電極材料を乾燥することが提案されている。 In a capacitor using an electrolyte containing a non-aqueous solvent (so-called non-aqueous electrolyte), mixing of moisture may affect the capacitor characteristics. Therefore, it has been studied to reduce the amount of moisture in the capacitor. For example, Patent Document 1 proposes drying an electrode material containing an electrode active material and a binder.
特開２００８－２５１７７６号公報JP 2008-251776 A
　特許文献１では、電極の水分を低減するため、電極材料の段階で乾燥処理を行っている。しかし、得られる活物質層の水分量は、２９００ｐｐｍ～５８００ｐｐｍと多く、十分に水分量を低減することは難しい。 In Patent Document 1, a drying process is performed at the electrode material stage in order to reduce the moisture of the electrode. However, the moisture content of the obtained active material layer is as large as 2900 ppm to 5800 ppm, and it is difficult to sufficiently reduce the moisture content.
　キャパシタ内の水分量を低減するには、キャパシタの構成要素をできるだけ乾燥する必要がある。セパレータおよび非水電解質の乾燥は比較的容易である。リチウムイオンキャパシタで使用される黒鉛および／またはハードカーボンを負極活物質として含む負極でも、これらの負極活物質は親水性が低いため、比較的乾燥し易い。しかし、正極活物質に使用される活性炭は比表面積が大きく、親水性が高いため、正極における水分量を低減することは難しい。 To reduce the amount of moisture in the capacitor, it is necessary to dry the components of the capacitor as much as possible. Drying of the separator and the non-aqueous electrolyte is relatively easy. Even in a negative electrode including graphite and / or hard carbon used as a negative electrode active material in a lithium ion capacitor, these negative electrode active materials have a low hydrophilicity and are relatively easy to dry. However, since the activated carbon used for the positive electrode active material has a large specific surface area and high hydrophilicity, it is difficult to reduce the water content in the positive electrode.
　正極では、アルミニウムを含む集電体が使用されている。正極集電体として、アルミニウムを含む三次元網目状の骨格を有する金属多孔体を用いた場合、アルミニウム箔を用いる場合と比べて、正極の厚みが大きくなるため、正極の水分量を低減することはさらに困難となる。また、金属多孔体は、表面積が非常に大きいため、正極の水分量が多いと、水が関与する副反応で生成した副生物が金属多孔体の表面に堆積し、正極の抵抗が高くなる。このような正極抵抗の増加は、アルミニウムを含む金属多孔体に特有の課題であり、表面積が小さなアルミニウム箔を用いる場合にはほとんど問題とならない。
　そこで、抵抗の増加が抑制されたキャパシタを得るのに有用なキャパシタ用正極、およびキャパシタの製造方法を提供することを目的とする。 In the positive electrode, a current collector containing aluminum is used. When using a metal porous body having a three-dimensional network-like skeleton containing aluminum as the positive electrode current collector, the thickness of the positive electrode is larger than when using an aluminum foil, so the water content of the positive electrode is reduced. Becomes even more difficult. In addition, since the metal porous body has a very large surface area, when the water content of the positive electrode is large, by-products generated by side reactions involving water are deposited on the surface of the metal porous body, and the resistance of the positive electrode is increased. Such an increase in positive electrode resistance is a problem peculiar to a metal porous body containing aluminum, and hardly causes a problem when an aluminum foil having a small surface area is used.
Then, it aims at providing the manufacturing method of the positive electrode for capacitors useful for obtaining the capacitor by which the increase in resistance was suppressed, and a capacitor.
　本発明の一局面は、正極集電体と、前記正極集電体に担持された正極合剤とを含むキャパシタ用正極であって、
　前記正極集電体は、アルミニウムまたはアルミニウム合金を含む三次元網目状の骨格を有し、
　前記正極合剤は、正極活物質およびバインダを少なくとも含み、
　前記正極活物質は、活性炭を含み、
　前記バインダは、融点およびＪＩＳ　Ｋ７１９１に準拠した荷重たわみ温度の少なくとも一方が２５０℃以上である高分子を含み、
　水分量は５００ｐｐｍ以下であるキャパシタ用正極に関する。 One aspect of the present invention is a positive electrode for a capacitor comprising a positive electrode current collector and a positive electrode mixture supported on the positive electrode current collector,
The positive electrode current collector has a three-dimensional network skeleton containing aluminum or an aluminum alloy,
The positive electrode mixture includes at least a positive electrode active material and a binder,
The positive electrode active material includes activated carbon,
The binder includes a polymer in which at least one of a melting point and a deflection temperature under load according to JIS K7191 is 250 ° C. or higher.
The moisture content relates to a positive electrode for a capacitor having 500 ppm or less.
　本発明の他の一局面は、
　正極を準備する工程（ａ）、
　前記正極と、負極と、正極および負極の間に介在するセパレータとで電極群を形成する工程（ｂ）、ならびに
　前記電極群および非水電解質をセルケース内に収容する工程（ｃ）を含み、
　前記工程（ａ）は、
　活性炭を含む正極活物質と、融点およびＪＩＳ　Ｋ７１９１に準拠した荷重たわみ温度の少なくとも一方が２５０℃以上である高分子を含むバインダとを、少なくとも含む正極合剤を調製する工程（ａ１）、
　前記正極合剤を、アルミニウムまたはアルミニウム合金を含む三次元網目状の骨格を有する正極集電体に充填する工程（ａ２）、
　前記工程（ａ２）で得られた充填物を厚み方向に圧縮する工程（ａ３）、ならびに
　前記工程（ａ３）で得られた圧縮物を、前記電極群が前記非水電解質と接触する前の状態において、前記正極の水分量が５００ｐｐｍ以下となるように、２００℃以上で、かつ前記高分子の前記融点および前記荷重たわみ温度の低い方よりも低い温度で乾燥する工程（ａ４）、を含む、キャパシタの製造方法に関する。 Another aspect of the present invention is:
Preparing a positive electrode (a),
A step (b) of forming an electrode group with the positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and a step (c) of accommodating the electrode group and a non-aqueous electrolyte in a cell case,
The step (a)
A step (a1) of preparing a positive electrode mixture containing at least a positive electrode active material containing activated carbon, and a binder containing at least one of a melting point and a deflection temperature under load in accordance with JIS K7191 of 250 ° C. or higher;
Filling the positive electrode mixture into a positive electrode current collector having a three-dimensional network skeleton containing aluminum or an aluminum alloy (a2),
The step (a3) of compressing the packing obtained in the step (a2) in the thickness direction, and the compressed product obtained in the step (a3) before the electrode group comes into contact with the nonaqueous electrolyte. And (a4) drying at a temperature lower than the melting point of the polymer and the lower deflection temperature under load so that the water content of the positive electrode is 500 ppm or less. The present invention relates to a method for manufacturing a capacitor.
　上記構成によれば、アルミニウムを含む三次元網目状の骨格を有する正極集電体を用い、かつ活性炭を含む正極活物質を用いた正極において、正極集電体の表面に副生成物が堆積するのを抑制することができる。その結果、正極の抵抗の増加が抑制されたキャパシタを得ることができる。 According to the above configuration, in the positive electrode using the positive electrode current collector having a three-dimensional network skeleton containing aluminum and the positive electrode active material containing activated carbon, a by-product is deposited on the surface of the positive electrode current collector. Can be suppressed. As a result, a capacitor in which an increase in positive electrode resistance is suppressed can be obtained.
本発明の一実施形態に係る製造方法により得られるキャパシタの外観を概略的に示す斜視図である。It is a perspective view which shows roughly the external appearance of the capacitor obtained by the manufacturing method which concerns on one Embodiment of this invention. 図１のキャパシタを正面から見たときの内部構造を概略的に示す一部断面図である。FIG. 2 is a partial cross-sectional view schematically showing an internal structure when the capacitor of FIG. 1 is viewed from the front. 図２のＩＩＩ－ＩＩＩ線による矢視断面図である。FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2.
　最初に、本発明の実施形態の内容を列記して説明する。
　本発明の一実施形態に係るキャパシタ用正極は、（１）正極集電体と、正極集電体に担持された正極合剤とを含む。正極集電体は、アルミニウムまたはアルミニウム合金を含む三次元網目状の骨格を有する。正極合剤は、正極活物質およびバインダを少なくとも含む。正極活物質は、活性炭を含む。バインダは、融点およびＪＩＳ　Ｋ７１９１に準拠した荷重たわみ温度の少なくとも一方が２５０℃以上である高分子を含む。正極の水分量は５００ｐｐｍ以下である。 First, the contents of the embodiment of the present invention will be listed and described.
A positive electrode for a capacitor according to an embodiment of the present invention includes (1) a positive electrode current collector and a positive electrode mixture supported on the positive electrode current collector. The positive electrode current collector has a three-dimensional network skeleton containing aluminum or an aluminum alloy. The positive electrode mixture includes at least a positive electrode active material and a binder. The positive electrode active material includes activated carbon. The binder includes a polymer in which at least one of a melting point and a deflection temperature under load according to JIS K7191 is 250 ° C. or higher. The water content of the positive electrode is 500 ppm or less.
　キャパシタの正極には、活性炭を含む正極活物質が使用されている。活性炭は、比表面積が大きく、親水性が高いため、活性炭には多くの水分が吸着し易い。そのため、活性炭を含む正極では、正極の水分量（または水分残存量）が多くなり易い。一方、リチウムイオンキャパシタなどのアルカリ金属イオンキャパシタおよびＥＤＬＣなどのキャパシタでは、電解質として、非水溶媒を含む非水電解質が用いられている。 The positive electrode active material containing activated carbon is used for the positive electrode of the capacitor. Since activated carbon has a large specific surface area and high hydrophilicity, a large amount of moisture is easily adsorbed on the activated carbon. Therefore, in the positive electrode containing activated carbon, the moisture content (or residual moisture content) of the positive electrode tends to increase. On the other hand, in an alkali metal ion capacitor such as a lithium ion capacitor and a capacitor such as EDLC, a nonaqueous electrolyte containing a nonaqueous solvent is used as an electrolyte.
　非水電解質を用いるキャパシタでは、キャパシタ内の水分量を低減できれば、ある程度、キャパシタ特性の低下を抑制できると考えられる。セパレータおよび非水電解質の水分量を低減するのは比較的容易である。また、黒鉛および／またはハードカーボンなどの活物質を用いる負極でも、活物質の疎水性が高いため、水分量の低減は容易である。しかし、活性炭は、親水性が非常に高いため、正極の水分量を低減することは難しい。特に、三次元網目状の骨格を有する金属多孔体を集電体として用いる場合、正極の厚みが大きくなり易いため、金属箔を集電体として用いる場合に比べて、水分を除去し難い。 In the case of a capacitor using a non-aqueous electrolyte, it is considered that a decrease in capacitor characteristics can be suppressed to some extent if the moisture content in the capacitor can be reduced. It is relatively easy to reduce the water content of the separator and the non-aqueous electrolyte. Further, even in a negative electrode using an active material such as graphite and / or hard carbon, the water content can be easily reduced because the active material is highly hydrophobic. However, since activated carbon is very hydrophilic, it is difficult to reduce the moisture content of the positive electrode. In particular, when a metal porous body having a three-dimensional network skeleton is used as a current collector, the thickness of the positive electrode tends to be large, so that it is difficult to remove moisture compared to the case where a metal foil is used as a current collector.
　正極中の水分量が多いと、水が関与する副反応が起こり易い。正極集電体として、アルミニウムを含む三次元網目状の骨格を有する金属多孔体を用いた場合、正極集電体の表面積が非常に大きい。そのため、電解質と、水との副反応により生成する副生物が、正極集電体の表面に堆積し、正極の抵抗が増加する。正極の抵抗が大きくなると、キャパシタのレート特性が低下する。なお、正極の抵抗とは「正極の電荷移動抵抗」を意味する。
　非水電解質を用いるキャパシタ内に多くの水分が残存すると、水の電気分解により水素ガスが発生し、キャパシタの内圧が上昇して、微小短絡が発生する場合がある。また、電解質と水との副反応により酸が発生し、アルミニウムを含む正極集電体を腐食して、キャパシタ容量の低下を招く場合がある。 If the amount of water in the positive electrode is large, side reactions involving water tend to occur. When a metal porous body having a three-dimensional network skeleton containing aluminum is used as the positive electrode current collector, the surface area of the positive electrode current collector is very large. Therefore, a by-product generated by a side reaction between the electrolyte and water is deposited on the surface of the positive electrode current collector, and the resistance of the positive electrode increases. As the resistance of the positive electrode increases, the rate characteristics of the capacitor decrease. The positive electrode resistance means "positive electrode charge transfer resistance".
If a large amount of moisture remains in a capacitor using a non-aqueous electrolyte, hydrogen gas is generated due to electrolysis of water, the internal pressure of the capacitor increases, and a micro short circuit may occur. In addition, an acid is generated due to a side reaction between the electrolyte and water, and the positive electrode current collector containing aluminum may be corroded, resulting in a decrease in capacitor capacity.
　本発明の実施形態によれば、正極の水分量が大きく低減しているため、アルミニウムを含む三次元網目状の骨格を有する正極集電体の表面に副生物が堆積することを抑制できる。よって、正極における抵抗の増加を抑制できる。正極において高い導電性を維持できることにより、キャパシタのレート特性の低下を抑制できる。また、水分量が低減された正極を用いることで、副反応が低減されるため、キャパシタ容量の低下を抑制することもできる。 According to the embodiment of the present invention, since the water content of the positive electrode is greatly reduced, it is possible to suppress the deposition of by-products on the surface of the positive electrode current collector having a three-dimensional network skeleton containing aluminum. Therefore, an increase in resistance at the positive electrode can be suppressed. By maintaining high conductivity in the positive electrode, it is possible to suppress a decrease in the rate characteristics of the capacitor. In addition, since the side reaction is reduced by using the positive electrode with a reduced amount of moisture, it is possible to suppress a reduction in the capacitor capacity.
　なお、本明細書中、正極の水分量（または水分残存量）とは、正極を用いて電極群を組み立てた後、非水電解質と接触させる前の正極の水分量（水分残存量）を意味する。より具体的には、セルケース内に電極群を収容した後、非水電解質をセルケースに収容する前の段階における正極の水分量（または水分残存量）であってもよい。正極の水分量は、正極集電体および正極集電体に担持された正極合剤における水分量の合計である。なお、非水電解質をセルケースに収容してキャパシタを組み立て、慣らし充放電後にガス抜きした後には、正極における水分量はさらに小さくなる。 In this specification, the moisture content (or residual moisture amount) of the positive electrode means the moisture content (residual moisture amount) of the positive electrode after assembling the electrode group using the positive electrode and before contacting with the nonaqueous electrolyte. To do. More specifically, it may be the moisture content (or residual moisture amount) of the positive electrode in a stage after the electrode group is accommodated in the cell case and before the nonaqueous electrolyte is accommodated in the cell case. The amount of water in the positive electrode is the total amount of water in the positive electrode current collector and the positive electrode mixture supported on the positive electrode current collector. In addition, after accommodating a nonaqueous electrolyte in a cell case, a capacitor is assembled, and after degassing after acclimation charging / discharging, the moisture content in the positive electrode is further reduced.
　本発明の実施形態のキャパシタ用正極では、バインダに含まれる高分子の融点および荷重たわみ温度のうち少なくとも一方が２５０℃以上である。バインダに含まれる高分子が融点および荷重たわみ温度のいずれか一方のみを有する場合には、その一方が２５０℃以上である。バインダに含まれる高分子が融点および荷重たわみ温度の双方を有する場合には、その融点および荷重たわみ温度のうちの一方のみが２５０℃以上であってもよいし、双方が２５０℃以上であってもよい。バインダに含まれる高分子の融点および荷重たわみ温度の少なくとも一方が２５０℃以上であることで、正極および／またはキャパシタの作製工程において、高分子の劣化が抑制され、バインダとしての機能が損なわれることが抑制される。
　なお、融点および荷重たわみ温度は、高分子の耐熱性の指標である。また、荷重たわみ温度は、ＪＩＳ　Ｋ７１９１（もしくは、ＩＳＯ７５またはＡＳＴＭ　Ｄ６４８）のＡ法に準拠して測定できる。測定時の荷重は、例えば、１．８０ＭＰａ～１．８２ＭＰａである。 In the positive electrode for a capacitor according to the embodiment of the present invention, at least one of the melting point and the deflection temperature under load of the polymer contained in the binder is 250 ° C. or higher. When the polymer contained in the binder has only one of the melting point and the deflection temperature under load, one of them is 250 ° C. or higher. When the polymer contained in the binder has both a melting point and a deflection temperature under load, only one of the melting point and the deflection temperature under load may be 250 ° C or higher, and both are 250 ° C or higher. Also good. When at least one of the melting point and the deflection temperature under load of the polymer contained in the binder is 250 ° C. or higher, deterioration of the polymer is suppressed in the positive electrode and / or capacitor manufacturing process, and the function as the binder is impaired. Is suppressed.
The melting point and the deflection temperature under load are indicators of the heat resistance of the polymer. Further, the deflection temperature under load can be measured in accordance with method A of JIS K7191 (or ISO 75 or ASTM D648). The load at the time of measurement is, for example, 1.80 MPa to 1.82 MPa.
　（２）正極の電荷移動抵抗は２Ω・ｃｍ2以下であることが好ましい。このような正極では、キャパシタのレート特性の向上効果がさらに高い。 (2) The charge transfer resistance of the positive electrode is preferably 2 Ω · cm 2 or less. In such a positive electrode, the effect of improving the rate characteristics of the capacitor is even higher.
　（３）高分子は、カルボキシアルキルセルロース、カルボキシアルキルセルロース塩、およびポリイミド樹脂からなる群より選択される少なくとも一種であることが好ましい。
　（４）高分子は、カルボキシメチルセルロース、カルボキシメチルセルロースのアルカリ金属塩、ポリイミド、およびポリアミドイミドからなる群より選択される少なくとも一種であることが好ましい。
　このような高分子を含むバインダを用いると、正極における水分量を低減し易いことに加え、バインダの劣化が抑制されるため、充放電を繰り返しても高いキャパシタ容量が得られ易い。なお、ポリイミド樹脂とは、ポリイミド、ポリアミドイミド、ポリエーテルイミド、ポリエステルイミドなどの樹脂のことをいう。 (3) The polymer is preferably at least one selected from the group consisting of carboxyalkyl cellulose, carboxyalkyl cellulose salt, and polyimide resin.
(4) The polymer is preferably at least one selected from the group consisting of carboxymethylcellulose, alkali metal salts of carboxymethylcellulose, polyimide, and polyamideimide.
When such a polymer-containing binder is used, it is easy to reduce the amount of water in the positive electrode, and the deterioration of the binder is suppressed. Therefore, a high capacitor capacity can be easily obtained even when charging and discharging are repeated. The polyimide resin refers to a resin such as polyimide, polyamideimide, polyetherimide, or polyesterimide.
　（５）正極の水分量は３００ｐｐｍ以下であることが好ましい。正極の水分量を大きく低減することで、正極における抵抗の増加を抑制する効果をさらに高めることができる。本発明の実施形態によれば、上記のようなバインダを用いるとともに、三次元網目状の骨格を有する正極集電体を用いることで、正極活物質および正極合剤の脱落を抑制することができ、充放電を繰り返しても高いキャパシタ容量を維持することができる。 (5) The water content of the positive electrode is preferably 300 ppm or less. By greatly reducing the moisture content of the positive electrode, the effect of suppressing an increase in resistance at the positive electrode can be further enhanced. According to the embodiment of the present invention, the use of the binder as described above and the use of the positive electrode current collector having a three-dimensional network skeleton can suppress the falling off of the positive electrode active material and the positive electrode mixture. Even when charging and discharging are repeated, a high capacitor capacity can be maintained.
　（６）正極は、５００μｍ～２０００μｍの厚みを有することが好ましい。上記のようなバインダを用いることで、正極の厚みがこのような範囲でも、正極の水分量を低減することができる。
　（７）バインダに占める前記高分子の量は、９０質量％～１００質量％であり、バインダの量は、正極活物質１００質量部に対して、１０質量部以下であることが好ましい。バインダの量がこのように少なくても、三次元網目状の骨格を有する正極集電体を用いることで、正極活物質および正極合剤の脱落を抑制することができ、充放電を繰り返しても高いキャパシタ容量を維持することができる。 (6) The positive electrode preferably has a thickness of 500 μm to 2000 μm. By using the binder as described above, the moisture content of the positive electrode can be reduced even when the thickness of the positive electrode is in such a range.
(7) The amount of the polymer in the binder is 90% by mass to 100% by mass, and the amount of the binder is preferably 10 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. Even if the amount of the binder is as small as this, by using the positive electrode current collector having a three-dimensional network skeleton, it is possible to suppress the falling off of the positive electrode active material and the positive electrode mixture, and even if charging and discharging are repeated. A high capacitor capacity can be maintained.
　（８）本発明の他の実施形態に係るキャパシタの製造方法は、正極を準備する工程（ａ）、正極と、負極と、正極および負極の間に介在するセパレータとで電極群を形成する工程（ｂ）、ならびに、電極群および非水電解質をセルケース内に収容する工程（ｃ）を含む。工程（ａ）は、活性炭を含む正極活物質と、融点およびＪＩＳ　Ｋ７１９１に準拠した荷重たわみ温度の少なくとも一方が２５０℃以上である高分子を含むバインダとを、少なくとも含む正極合剤を調製する工程（ａ１）、正極合剤を、アルミニウムまたはアルミニウム合金を含む三次元網目状の骨格を有する正極集電体に充填する工程（ａ２）、工程（ａ２）で得られた充填物を厚み方向に圧縮する工程（ａ３）、前記工程（ａ３）で得られた圧縮物を、電極群が非水電解質と接触する前の状態において、正極の水分量が５００ｐｐｍ以下となるように、２００℃以上で、かつ高分子の融点および荷重たわみ温度の低い方よりも低い温度で乾燥する工程（ａ４）を含む。
　このような製造方法によれば、正極における水分量を大幅に低減できるため、正極の抵抗の増加を抑制できる。従って、レート特性の低下が抑制されたキャパシタを得ることができる。
　なお、「高分子の融点および荷重たわみ温度の低い方よりも低い温度」とは、高分子が融点および荷重たわみ温度のいずれか一方のみを有する場合にはその一方よりも低い温度であり、高分子が融点および荷重たわみ温度の双方を有する場合にはそのいずれよりも低い温度である。 (8) The method for manufacturing a capacitor according to another embodiment of the present invention includes a step (a) of preparing a positive electrode, a step of forming an electrode group with a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. (B) and the process (c) which accommodates an electrode group and a nonaqueous electrolyte in a cell case. Step (a) is a step of preparing a positive electrode mixture containing at least a positive electrode active material containing activated carbon and a binder containing a polymer having a melting point and a deflection temperature under load in accordance with JIS K7191 of 250 ° C. or higher. (A1) The step (a2) and the step (a2) of filling the positive electrode mixture with a positive electrode current collector having a three-dimensional network skeleton containing aluminum or an aluminum alloy are compressed in the thickness direction. Step (a3), the compressed product obtained in the step (a3) at a temperature of 200 ° C. or higher so that the moisture content of the positive electrode is 500 ppm or less before the electrode group is in contact with the nonaqueous electrolyte. And a step (a4) of drying at a temperature lower than the lower one of the melting point and the deflection temperature under load of the polymer.
According to such a manufacturing method, the amount of water in the positive electrode can be significantly reduced, and thus an increase in resistance of the positive electrode can be suppressed. Therefore, it is possible to obtain a capacitor in which the deterioration of rate characteristics is suppressed.
The “temperature lower than the lower one of the melting point and the deflection temperature under load of the polymer” means a temperature lower than one when the polymer has only one of the melting point and the deflection temperature under load. When a molecule has both a melting point and a deflection temperature under load, the temperature is lower than both.
　（９）工程（ａ４）では、前記圧縮物を、減圧下、遠赤外線下、または減圧下および遠赤外線下で乾燥することが好ましい。このような乾燥方法により、正極を乾燥すると、正極の表面だけでなく、内部まで比較的均一に乾燥し易い。よって、正極の抵抗の増加をより効果的に抑制できる。 (9) In the step (a4), the compressed product is preferably dried under reduced pressure, far infrared rays, or reduced pressure and far infrared rays. When the positive electrode is dried by such a drying method, not only the surface of the positive electrode but also the inside thereof is easily dried relatively uniformly. Therefore, an increase in resistance of the positive electrode can be more effectively suppressed.
　（１０）好ましい実施形態において、非水電解質は、アルカリ金属イオン伝導性を有し、負極は、負極集電体と、前記負極集電体に担持され、かつ負極活物質を含む負極合剤とを含む。負極集電体は、三次元網目状の金属の骨格を有し、負極活物質は、アルカリ金属イオンを可逆的に担持する材料を含むことが好ましい。このような実施形態に係る製造方法で得られるキャパシタは、アルカリ金属イオンキャパシタと称される。使用される負極活物質は、疎水性が高く、負極の水分量を低減し易い。よって、キャパシタ内の水分量をさらに低減することができ、副反応を抑制する効果がさらに高まる。 (10) In a preferred embodiment, the non-aqueous electrolyte has alkali metal ion conductivity, the negative electrode is a negative electrode current collector, and a negative electrode mixture supported on the negative electrode current collector and including a negative electrode active material. including. The negative electrode current collector preferably has a three-dimensional network metal skeleton, and the negative electrode active material preferably contains a material that reversibly carries alkali metal ions. The capacitor obtained by the manufacturing method according to such an embodiment is referred to as an alkali metal ion capacitor. The negative electrode active material used has high hydrophobicity and easily reduces the moisture content of the negative electrode. Therefore, the amount of moisture in the capacitor can be further reduced, and the effect of suppressing side reactions is further enhanced.
［発明の実施形態の詳細］
　本発明の実施形態に係るキャパシタ用正極およびこの正極を用いたキャパシタ、ならびにキャパシタの製造方法の具体例を、適宜図面を参照しつつ以下に説明する。なお、本発明はこれらの例示に限定されるものではなく、添付の特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内での全ての変更が含まれることが意図される。 [Details of the embodiment of the invention]
Specific examples of a positive electrode for a capacitor, a capacitor using the positive electrode, and a method for manufacturing the capacitor according to an embodiment of the present invention will be described below with reference to the drawings as appropriate. In addition, this invention is not limited to these illustrations, is shown by the attached claim, and is intended that all the changes within the meaning and range equivalent to the claim are included. .
　（キャパシタ用正極）
　正極は、正極集電体と、正極集電体に担持された正極合剤とを含み、正極合剤は、正極活物質およびバインダを少なくとも含む。 (Positive electrode for capacitors)
The positive electrode includes a positive electrode current collector and a positive electrode mixture supported on the positive electrode current collector, and the positive electrode mixture includes at least a positive electrode active material and a binder.
　（正極集電体）
　正極集電体は、アルミニウムまたはアルミニウム合金を含む。正極集電体中のアルミニウムの含有量は、例えば、８０質量％以上、好ましくは９０質量％以上、さらに好ましくは９５質量％以上または９８質量％以上である。正極集電体中のアルミニウムの含有量は、１００質量％以下であり、９９．９質量％以下であってもよい。これらの下限値と上限値とは任意に組み合わせることができる。正極集電体中のアルミニウムの含有量は、例えば、８０質量％～１００質量％、または９５質量％～１００質量％であってもよい。正極集電体には、不可避的に混入する不純物が含まれていてもよい。 (Positive electrode current collector)
The positive electrode current collector contains aluminum or an aluminum alloy. The content of aluminum in the positive electrode current collector is, for example, 80% by mass or more, preferably 90% by mass or more, and more preferably 95% by mass or more or 98% by mass or more. The content of aluminum in the positive electrode current collector is 100% by mass or less, and may be 99.9% by mass or less. These lower limit values and upper limit values can be arbitrarily combined. The content of aluminum in the positive electrode current collector may be, for example, 80% by mass to 100% by mass, or 95% by mass to 100% by mass. The positive electrode current collector may contain impurities inevitably mixed therein.
　正極集電体に含まれるアルミニウム合金としては、例えば、アルミニウム－鉄合金、アルミニウム－銅合金、アルミニウム－マンガン合金、アルミニウム－ケイ素合金、アルミニウム－マグネシウム合金、アルミニウム－マグネシウム－ケイ素合金、アルミニウム－亜鉛合金、アルミニウム－ニッケル合金などが挙げられる。 Examples of the aluminum alloy contained in the positive electrode current collector include an aluminum-iron alloy, an aluminum-copper alloy, an aluminum-manganese alloy, an aluminum-silicon alloy, an aluminum-magnesium alloy, an aluminum-magnesium-silicon alloy, and an aluminum-zinc alloy. And aluminum-nickel alloy.
　正極集電体は、アルミニウムまたはアルミニウム合金を含む三次元網目状の骨格を有する。三次元網目状の骨格とは、アルミニウムまたはアルミニウム合金で形成された繊維部（または棒状部）を有し、繊維部が三次元的に連結して網目状のネットワークを形成した骨格またはその構造であってもよい。つまり、正極集電体は、複数の繊維部（または棒状部）を含むことができ、これらの複数の繊維部は、三次元的に連結して三次元網目状の骨格を形成している。 The positive electrode current collector has a three-dimensional network skeleton containing aluminum or an aluminum alloy. A three-dimensional network skeleton is a skeleton or structure having a fiber part (or rod-like part) formed of aluminum or an aluminum alloy, and the fiber parts are three-dimensionally connected to form a network network. There may be. That is, the positive electrode current collector can include a plurality of fiber portions (or rod-shaped portions), and the plurality of fiber portions are three-dimensionally connected to form a three-dimensional network skeleton.
　三次元網目状の正極集電体は、連続空隙を有する樹脂製の多孔体（樹脂発泡体、樹脂製の不織布など）を、例えば、めっき処理などにより、集電体を構成する金属（具体的には、アルミニウムおよび／またはアルミニウム合金）で被覆することにより形成できる。得られる正極集電体は、樹脂製発泡体の形状に対応して、１つ１つがセル状の空孔を多数有しており、これらのセル状の空孔が連通した連続空隙（つまり、連通孔）を有する。隣り合うセル状の空孔の間には、開口（または窓）が形成され、この開口により空孔が連通した状態となることが好ましい。 The three-dimensional network positive electrode current collector is a resin porous material (resin foam, resin nonwoven fabric, etc.) having continuous voids, for example, a metal constituting the current collector by plating or the like (specifically Can be formed by coating with aluminum and / or an aluminum alloy. Each of the obtained positive electrode current collectors has a large number of cell-like pores corresponding to the shape of the resin foam, and continuous pores (that is, these cell-like pores communicated) (that is, Communication hole). It is preferable that an opening (or window) is formed between the adjacent cellular holes, and the holes communicate with each other.
　キャパシタを高容量化する観点から、正極集電体の気孔率は、例えば、３０体積％～９９体積％、好ましくは５０体積％～９８体積％、さらに好ましくは８０体積％～９８体積％または９０体積％～９８体積％である。三次元網目状の骨格における平均空孔径（連通するセル状の空孔の平均径）は、正極合剤の充填性および保持性の観点、ならびに水分を除去し易い観点から、例えば、５０μｍ～１０００μｍ、好ましくは１００μｍ～９００μｍ、さらに好ましくは３５０μｍ～９００μｍである。なお、平均空孔径は、正極集電体（または正極）の厚みよりも小さいことが好ましい。 From the viewpoint of increasing the capacity of the capacitor, the porosity of the positive electrode current collector is, for example, 30% to 99% by volume, preferably 50% to 98% by volume, and more preferably 80% to 98% by volume or 90%. From volume% to 98 volume%. The average pore diameter in the three-dimensional network skeleton (average diameter of cell-like pores communicating with each other) is, for example, 50 μm to 1000 μm from the viewpoint of filling and retaining properties of the positive electrode mixture and easy removal of moisture. The thickness is preferably 100 μm to 900 μm, more preferably 350 μm to 900 μm. The average pore diameter is preferably smaller than the thickness of the positive electrode current collector (or positive electrode).
　好ましい実施形態では、正極集電体の三次元網目状の骨格は、内部に空洞を有する（つまり、中空である）。骨格内の空洞は、樹脂製の多孔体の除去により形成される。正極集電体の骨格内の空洞は、連通孔状であってもよく、このような骨格は、トンネル状またはチューブ状になっている。中空の骨格を有する正極集電体は、嵩高い三次元構造を有しながらも、極めて軽量である。骨格内部の空洞の幅は、平均値で、例えば、０．５μｍ～５μｍ、好ましくは１μｍ～４μｍまたは２μｍ～３μｍである。 In a preferred embodiment, the three-dimensional network skeleton of the positive electrode current collector has a cavity inside (that is, is hollow). The cavity in the skeleton is formed by removing the porous resin body. The cavity in the skeleton of the positive electrode current collector may have a communication hole shape, and such a skeleton has a tunnel shape or a tube shape. A positive electrode current collector having a hollow skeleton is extremely lightweight while having a bulky three-dimensional structure. The average width of the cavity inside the skeleton is, for example, 0.5 μm to 5 μm, preferably 1 μm to 4 μm, or 2 μm to 3 μm.
　（正極合剤）
　正極集電体に担持される正極合剤は、正極活物質およびバインダを少なくとも含む。
　正極活物質は、活性炭を含む。活性炭は、キャパシタの電解質に含まれるアニオンおよびカチオンのうち、少なくともアニオンを可逆的に担持することにより、正極活物質として機能する。正極の電位によって、活性炭は、キャパシタ内において、アニオンおよびカチオンの双方を可逆的に担持することができる。活性炭は、充放電時に非ファラデー反応により、少なくともアニオンを可逆的に担持することができる。具体的には、活性炭は、充放電時に、少なくともアニオンを吸着および脱着することができる。 (Positive electrode mixture)
The positive electrode mixture supported on the positive electrode current collector contains at least a positive electrode active material and a binder.
The positive electrode active material includes activated carbon. Activated carbon functions as a positive electrode active material by carrying at least an anion reversibly among the anions and cations contained in the electrolyte of the capacitor. Depending on the potential of the positive electrode, the activated carbon can reversibly carry both anions and cations in the capacitor. Activated carbon can reversibly carry at least an anion by a non-Faraday reaction during charging and discharging. Specifically, activated carbon can adsorb and desorb at least anions during charging and discharging.
　活性炭としては、キャパシタに使用される公知のものを使用できる。活性炭の原料としては、例えば、木材；ヤシ殻；パルプ廃液；石炭またはその熱分解により得られる石炭系ピッチ；重質油またはその熱分解により得られる石油系ピッチ；フェノール樹脂などが挙げられる。活性炭は、賦活処理されていなくてもよいが、賦活処理されたものであることが好ましい。 As the activated carbon, known ones used for capacitors can be used. Examples of the raw material of activated carbon include wood; coconut shells; pulp waste liquid; coal or coal-based pitch obtained by thermal decomposition thereof; heavy oil or petroleum-based pitch obtained by thermal decomposition thereof; phenol resin and the like. The activated carbon may not be activated, but is preferably activated.
　活性炭の平均粒径は、特に限定されないが、２０μｍ以下であることが好ましく、３μｍ～１５μｍであることがより好ましい。
　本明細書中、平均粒径とは、レーザー回折式の粒度分布測定で得られる粒度分布における体積基準のメディアン径を意味する。 The average particle diameter of the activated carbon is not particularly limited, but is preferably 20 μm or less, and more preferably 3 μm to 15 μm.
In this specification, the average particle diameter means a volume-based median diameter in a particle size distribution obtained by laser diffraction particle size distribution measurement.
　活性炭の比表面積（ＢＥＴ比表面積）は、特に限定されないが、８００ｍ2／ｇ～３０００ｍ2／ｇが好ましく、１５００ｍ2／ｇ～３０００ｍ2／ｇがさらに好ましい。比表面積がこのような範囲である場合、キャパシタの静電容量を大きくする上で有利であるとともに、内部抵抗を小さくし易い。 The specific surface area (BET specific surface area) of the activated carbon is not particularly limited, but is preferably 800 m 2 / g to 3000 m 2 / g, and more preferably 1500 m 2 / g to 3000 m 2 / g. When the specific surface area is in such a range, it is advantageous for increasing the capacitance of the capacitor, and it is easy to reduce the internal resistance.
　活性炭は、一種を単独で用いてもよく、原料、平均粒径および／または比表面積が異なる二種以上を組み合わせて使用してもよい。
　正極活物質は、活性炭以外の活物質（例えば、メソポーラスカーボン、カーボンナノチューブなど）を含んでもよい。正極活物質中の活性炭の含有量は、８０質量％～１００質量％であることが好ましく、９０質量％～１００質量％であることがさらに好ましい。また、正極活物質が、活性炭のみを含む場合も好ましい。 Activated carbon may be used alone or in combination of two or more different raw materials, average particle diameters and / or specific surface areas.
The positive electrode active material may include an active material other than activated carbon (for example, mesoporous carbon, carbon nanotube, etc.). The content of activated carbon in the positive electrode active material is preferably 80% by mass to 100% by mass, and more preferably 90% by mass to 100% by mass. It is also preferable that the positive electrode active material contains only activated carbon.
　正極合剤に含まれるバインダは、結着性を有する高分子を含む。また、バインダに含まれる高分子の融点およびＪＩＳ　Ｋ７１９１に準拠した荷重たわみ温度の少なくとも一方が２５０℃以上である。このような高分子は、耐熱性が高く、正極およびキャパシタの作製工程において、劣化し難いため、比較的高い温度で乾燥することができる。本発明の実施形態では、三次元網目状の正極集電体を用いるため、正極の水分を除去し難いが、このような高分子を含むバインダを用いることで、より高い温度での乾燥が可能となり、正極に含まれる水分量を大幅に低減できる。また、三次元網目状の正極集電体を用いることで、正極活物質および／または正極合剤の脱落が抑制され、充放電を繰り返しても高いキャパシタ容量を維持することができる。 The binder contained in the positive electrode mixture contains a polymer having binding properties. In addition, at least one of the melting point of the polymer contained in the binder and the deflection temperature under load in accordance with JIS K7191 is 250 ° C. or higher. Such a polymer has high heat resistance and hardly deteriorates in the manufacturing process of the positive electrode and the capacitor. Therefore, the polymer can be dried at a relatively high temperature. In the embodiment of the present invention, since the positive electrode current collector having a three-dimensional network shape is used, it is difficult to remove moisture from the positive electrode. However, by using a binder containing such a polymer, drying at a higher temperature is possible. Thus, the amount of water contained in the positive electrode can be greatly reduced. Moreover, by using a three-dimensional network positive electrode current collector, the positive electrode active material and / or the positive electrode mixture are prevented from falling off, and a high capacitor capacity can be maintained even after repeated charge and discharge.
　高分子の融点および荷重たわみ温度の少なくとも一方は、２５０℃以上であることが好ましく、２７０℃以上であることがより好ましい。高分子の融点および荷重たわみ温度の少なくとも一方がこのような温度であることで、正極および／またはキャパシタの作製工程における乾燥をより高い温度で行うことが可能となるため、水分量を大幅に低減できる。高分子の融点および荷重たわみ温度の少なくとも一方は、例えば、５００℃以下であり、好ましくは４００℃以下である。
　これらの下限値と上限値とは任意に組み合わせることができる。例えば、高分子の融点および荷重たわみ温度の少なくとも一方の好ましい温度範囲は、２５０℃～５００℃であってもよいし、または２７０℃～４００℃であってもよい。 At least one of the melting point and the deflection temperature under load of the polymer is preferably 250 ° C. or higher, and more preferably 270 ° C. or higher. Since at least one of the melting point of the polymer and the deflection temperature under load is such a temperature, it becomes possible to perform drying at a higher temperature in the manufacturing process of the positive electrode and / or capacitor, so that the water content is greatly reduced. it can. At least one of the melting point and the deflection temperature under load of the polymer is, for example, 500 ° C. or less, and preferably 400 ° C. or less.
These lower limit values and upper limit values can be arbitrarily combined. For example, a preferable temperature range of at least one of the melting point and the deflection temperature under load of the polymer may be 250 ° C. to 500 ° C., or 270 ° C. to 400 ° C.
　高分子の融点および荷重たわみ温度のいずれか一方のみを有する場合、その一方は、２００℃以上または２００℃超であることが好ましく、２２０℃以上または２２０℃超であることがより好ましく、２５０℃以上であることがさらに好ましく、２７０℃以上であることが特に好ましい。高分子が融点および荷重たわみ温度の双方を有する場合、双方とも、２００℃以上または２００℃超であることが好ましく、２２０℃以上または２２０℃超であることがより好ましく、２５０℃以上であることがさらに好ましく、２７０℃以上であることが特に好ましい。
　このような高分子を含むバインダを用いることによって、正極およびキャパシタの作製工程において、比較的高い温度で乾燥することが可能となり、正極に含まれる水分量を大幅に低減できる。 In the case of having only one of the melting point and the deflection temperature under load of the polymer, one of them is preferably 200 ° C or higher or higher than 200 ° C, more preferably 220 ° C or higher or higher than 220 ° C, more preferably 250 ° C. More preferably, it is more preferably 270 ° C. or higher. When the polymer has both a melting point and a deflection temperature under load, both are preferably 200 ° C or higher or higher than 200 ° C, more preferably 220 ° C or higher or higher than 220 ° C, and 250 ° C or higher. Is more preferable, and it is especially preferable that it is 270 degreeC or more.
By using such a binder containing a polymer, it becomes possible to dry at a relatively high temperature in the manufacturing process of the positive electrode and the capacitor, and the amount of water contained in the positive electrode can be greatly reduced.
　また、高分子が融点および荷重たわみ温度のいずれか一方のみを有する場合、その一方は、例えば５００℃以下であり、好ましくは４００℃以下である。高分子が融点および荷重たわみ温度の双方を有する場合、双方とも、例えば５００℃以下であり、好ましくは４００℃以下である。 Further, when the polymer has only one of the melting point and the deflection temperature under load, one of them is, for example, 500 ° C. or less, preferably 400 ° C. or less. When the polymer has both a melting point and a deflection temperature under load, both are, for example, 500 ° C. or lower, and preferably 400 ° C. or lower.
　高分子は、正極活物質および／または正極合剤の脱落を抑制する観点から、ある程度の結着性を有する必要がある。本発明の実施形態では、三次元網目状の正極集電体を用いるため、高分子に求められる結着性はそれほど高くなくてもよく、キャパシタの電極において使用されるバインダに求められる結着性に限らず、正極合剤（具体的には、正極合剤スラリー）に粘性を付与できる程度の結着性であってもよい。 The polymer needs to have a certain degree of binding properties from the viewpoint of suppressing the removal of the positive electrode active material and / or the positive electrode mixture. In the embodiment of the present invention, since the three-dimensional network positive electrode current collector is used, the binding property required for the polymer may not be so high, and the binding property required for the binder used in the electrode of the capacitor. The binding property may be such that viscosity can be imparted to the positive electrode mixture (specifically, the positive electrode mixture slurry).
　バインダに使用される上記の高分子としては、例えば、セルロースエーテル、ポリイミド樹脂（ポリイミド、ポリアミドイミド、ポリエーテルイミド、ポリエステルイミドなど）、ポリアミド樹脂（芳香族ポリアミドなど）などが挙げられる。セルロースエーテルとしては、カルボキシメチルセルロース（ＣＭＣ：ｃａｒｂｏｘｙｍｅｔｈｙｌ　ｃｅｌｌｕｌｏｓｅ）などのカルボキシアルキルセルロース；ＣＭＣのナトリウム塩などのカルボキシアルキルセルロース塩（ナトリウム塩、カリウム塩などのアルカリ金属塩；アンモニウム塩など）；ヒドロキシエチルセルロース、ヒドロキシプロピルメチルセルロースなどのヒドロキシアルキルセルロースなどが例示できる。これらの高分子は、一種を単独でまたは二種以上を組み合わせて使用できる。 Examples of the polymer used for the binder include cellulose ether, polyimide resin (polyimide, polyamideimide, polyetherimide, polyesterimide, etc.), polyamide resin (aromatic polyamide, etc.), and the like. Examples of cellulose ethers include carboxyalkyl celluloses such as carboxymethyl cellulose (CMC); carboxyalkyl cellulose salts such as sodium salt of CMC (alkali metal salts such as sodium salt and potassium salt; ammonium salts); hydroxyethyl cellulose, hydroxy Examples thereof include hydroxyalkylcellulose such as propylmethylcellulose. These polymers can be used singly or in combination of two or more.
　耐熱性が高く、バインダとしての機能に優れる観点から、上記高分子のうち、カルボキシアルキルセルロースおよびその塩、ポリイミド樹脂が好ましい。中でも、ＣＭＣなどのカルボキシＣ1-3アルキルセルロースおよびその塩（ＣＭＣのアルカリ金属塩など）、ポリイミド、およびポリアミドイミドなどが好ましい。
　正極における抵抗を低減することが比較的容易である観点から、ＣＭＣおよびＣＭＣ塩などのセルロースエーテル（カルボキシアルキルセルロースなど）が好ましい。 Of the above polymers, carboxyalkyl cellulose, its salt, and polyimide resin are preferred from the viewpoint of high heat resistance and excellent function as a binder. Among these, carboxy C 1-3 alkyl cellulose such as CMC and salts thereof (such as alkali metal salt of CMC), polyimide, and polyamideimide are preferable.
From the viewpoint that it is relatively easy to reduce the resistance in the positive electrode, cellulose ethers (such as carboxyalkyl cellulose) such as CMC and CMC salts are preferable.
　セルロースエーテルでは、セルロースの無水グルコース単位１個当たり３個のヒドロキシル基の一部または全てがエーテル結合に変換されている。セルロースエーテルのエーテル化度は、エーテル結合の導入量の平均値であり、０～３の値を取り得る。
　正極合剤における分散性、結着性および／または水分量の低減し易さなどの観点から、バインダに使用されるセルロースエーテルのエーテル化度は、０．６～１．５であることが好ましく、０．６～１．０であることがさらに好ましい。 In cellulose ethers, some or all of the three hydroxyl groups per anhydroglucose unit of cellulose are converted to ether linkages. The degree of etherification of cellulose ether is an average value of the amount of ether bonds introduced, and can take a value of 0 to 3.
From the viewpoint of dispersibility, binding properties and / or ease of water content reduction in the positive electrode mixture, the degree of etherification of the cellulose ether used in the binder is preferably 0.6 to 1.5. More preferably, it is 0.6 to 1.0.
　耐熱性、正極合剤における分散性、および／または結着性などの観点から、セルロースエーテルは、ある程度の分子量または重合度を有することが望ましい。セルロースエーテルの分子量または重合度は、しばしば、セルロースエーテルを所定濃度（例えば、１質量％～２質量％の濃度）で含む水溶液の粘度を指標として評価される。バインダに使用されるセルロースエーテルは、その１質量％濃度の水溶液の粘度が、２５℃において、１０ｍＰａ・ｓ～３００ｍＰａ・ｓであるものが好ましく、１０ｍＰａ・ｓ～５０ｍＰａ・ｓであるものがさらに好ましい。このような粘度を示すセルロースエーテルを用いる場合、正極における抵抗の増加を抑制する効果をさらに高めることもできる。 From the viewpoint of heat resistance, dispersibility in the positive electrode mixture, and / or binding property, it is desirable that the cellulose ether has a certain molecular weight or degree of polymerization. The molecular weight or degree of polymerization of cellulose ether is often evaluated using the viscosity of an aqueous solution containing cellulose ether at a predetermined concentration (for example, a concentration of 1% by mass to 2% by mass) as an index. The cellulose ether used in the binder preferably has a viscosity of an aqueous solution having a concentration of 1% by mass of 10 mPa · s to 300 mPa · s at 25 ° C., more preferably 10 mPa · s to 50 mPa · s. . When using the cellulose ether which shows such a viscosity, the effect which suppresses the increase in resistance in a positive electrode can also be heightened further.
　バインダに占める上記の高分子の量は、例えば、８０質量％～１００質量％であり、好ましくは９０質量％～１００質量％である。バインダを、上記の高分子のみで構成してもよい。高分子の量がこのような範囲である場合、バインダの耐熱性を高め易いため、正極の水分量をより容易に低減することができる。 The amount of the polymer in the binder is, for example, 80% by mass to 100% by mass, and preferably 90% by mass to 100% by mass. You may comprise a binder only with said polymer | macromolecule. When the amount of the polymer is within such a range, the heat resistance of the binder can be easily increased, so that the moisture content of the positive electrode can be more easily reduced.
　本発明の実施形態では、三次元網目状の骨格を有する正極集電体を用いることで、正極活物質および正極合剤の脱落を抑制することができる。そのため、バインダの量を少なくしても、充放電を安定して行うことができ、高いキャパシタ容量を維持することができる。バインダの量は、正極活物質１００質量部に対して、例えば、１０質量部以下（例えば、０．１質量部～１０質量部）であり、好ましくは０．５質量部～５質量部であり、さらに好ましくは１質量部～４質量部である。 In the embodiment of the present invention, by using a positive electrode current collector having a three-dimensional network skeleton, it is possible to prevent the positive electrode active material and the positive electrode mixture from falling off. Therefore, even if the amount of the binder is reduced, charging / discharging can be performed stably, and a high capacitor capacity can be maintained. The amount of the binder is, for example, 10 parts by mass or less (eg, 0.1 to 10 parts by mass), preferably 0.5 to 5 parts by mass with respect to 100 parts by mass of the positive electrode active material. More preferably, it is 1 to 4 parts by mass.
　正極合剤は、さらに導電助剤を含むことができる。導電助剤の種類は、特に制限されず、アセチレンブラック、ケッチェンブラックなどのカーボンブラック；黒鉛（鱗片状黒鉛、土状黒鉛などの天然黒鉛；人造黒鉛など）；酸化ルテニウムなどの導電性化合物；炭素繊維、金属繊維などの導電性繊維などが挙げられる。導電助剤は、一種を単独でまたは二種以上を組み合わせて使用できる。導電助剤の量は、正極活物質１００質量部に対して、例えば１質量部～２０質量部、または好ましくは５質量部～１５質量部である。 The positive electrode mixture can further contain a conductive additive. The type of the conductive aid is not particularly limited, and carbon black such as acetylene black and ketjen black; graphite (natural graphite such as flake graphite and earth graphite; artificial graphite and the like); conductive compound such as ruthenium oxide; Examples thereof include conductive fibers such as carbon fibers and metal fibers. A conductive support agent can be used individually by 1 type or in combination of 2 or more types. The amount of the conductive assistant is, for example, 1 part by mass to 20 parts by mass, or preferably 5 parts by mass to 15 parts by mass with respect to 100 parts by mass of the positive electrode active material.
　本発明の実施形態では、親水性が高い活性炭を含む正極活物質を用いるにも拘わらず、正極の水分量を大幅に低減できる。正極の水分量は、５００ｐｐｍ以下であり、好ましくは４００ｐｐｍ以下、より好ましくは３００ｐｐｍ以下、さらに好ましくは２００ｐｐｍ以下である。正極の水分量はできるだけ小さいことが望ましいが、０ｐｐｍにすることは難しい。したがって、正極の水分量は、例えば、０ｐｐｍ超、または１０ｐｐｍ以上であってもよい。正極の水分量が５００ｐｐｍを超えると、キャパシタ内において、水が関与する副反応が顕著になり、正極の抵抗が大きく増加し、このため、キャパシタのレート特性が低下する。また、ガス発生が顕著になり、キャパシタ容量が低下する。 In the embodiment of the present invention, the moisture content of the positive electrode can be greatly reduced despite the use of a positive electrode active material containing activated carbon having high hydrophilicity. The moisture content of the positive electrode is 500 ppm or less, preferably 400 ppm or less, more preferably 300 ppm or less, and still more preferably 200 ppm or less. The moisture content of the positive electrode is desirably as small as possible, but it is difficult to make it 0 ppm. Therefore, the moisture content of the positive electrode may be, for example, more than 0 ppm or 10 ppm or more. When the moisture content of the positive electrode exceeds 500 ppm, the side reaction involving water becomes prominent in the capacitor, and the resistance of the positive electrode is greatly increased. For this reason, the rate characteristics of the capacitor are deteriorated. In addition, gas generation becomes significant and the capacitor capacity decreases.
　正極の水分量は、カールフィッシャー法により測定することができる。カールフィッシャー法は、容量滴定法と電量滴定法とに分類されるが、ここでは、分析精度の高い電量滴定法を採用する。また、水分量測定機器には、市販のカールフィッシャー水分計（例えば、京都電子工業（株）製のＭＫＣ－６１０）を用いることができる。 The moisture content of the positive electrode can be measured by the Karl Fischer method. The Karl Fischer method is classified into a volumetric titration method and a coulometric titration method. Here, a coulometric titration method with high analysis accuracy is adopted. A commercially available Karl Fischer moisture meter (for example, MKC-610 manufactured by Kyoto Denshi Kogyo Co., Ltd.) can be used as the moisture content measuring instrument.
　本発明の実施形態に係る正極では、三次元網目状の骨格を有するアルミニウムを含む正極集電体を用いているにも拘わらず、正極集電体の表面に副生物が堆積することが抑制され、抵抗の増加が抑制される。正極の電荷移動抵抗は、２Ω・ｃｍ2以下（具体的には、０Ω・ｃｍ2～２Ω・ｃｍ2）であることが好ましく、１．５Ω・ｃｍ2以下であることがより好ましく、１．４Ω・ｃｍ2以下であることがさらに好ましく、１．２Ω・ｃｍ2以下であることが特に好ましい。正極の電荷移動抵抗は、セルが小さくなると大きくなる傾向があるため、例えば、容量が２Ａｈ～４Ａｈのセルにおいて、正極の電荷移動抵抗が上記のような範囲となることが好ましい。正極の電荷移動抵抗は、例えば、交流インピーダンス法により求めることができる。 In the positive electrode according to the embodiment of the present invention, although a positive electrode current collector containing aluminum having a three-dimensional network skeleton is used, it is possible to suppress the accumulation of by-products on the surface of the positive electrode current collector. , The increase in resistance is suppressed. The charge transfer resistance of the positive electrode is preferably 2 Ω · cm 2 or less (specifically, 0 Ω · cm 2 to 2 Ω · cm 2 ), more preferably 1.5 Ω · cm 2 or less. 4Ω · cm 2 or less is more preferable, and 1.2Ω · cm 2 or less is particularly preferable. Since the charge transfer resistance of the positive electrode tends to increase as the cell becomes smaller, for example, in a cell having a capacity of 2 Ah to 4 Ah, the charge transfer resistance of the positive electrode is preferably in the above range. The charge transfer resistance of the positive electrode can be obtained by, for example, an AC impedance method.
　正極の厚みは、例えば、１００μｍ～２０００μｍの範囲から選択でき、好ましくは３００μｍ～２０００μｍ、さらに好ましくは５００μｍ～２０００μｍである。正極の厚みがこのような範囲である場合、高いキャパシタ容量が得られ易い。正極の厚みが大きい場合、例えば、正極の厚みが３００μｍ以上または５００μｍ以上である場合であっても、本発明の実施形態によれば、特定のバインダを用いることにより、水分量を効果的に低減することができる。 The thickness of the positive electrode can be selected from the range of 100 μm to 2000 μm, for example, preferably 300 μm to 2000 μm, more preferably 500 μm to 2000 μm. When the thickness of the positive electrode is in such a range, a high capacitor capacity is easily obtained. When the thickness of the positive electrode is large, for example, even when the thickness of the positive electrode is 300 μm or more or 500 μm or more, according to the embodiment of the present invention, the moisture content is effectively reduced by using a specific binder. can do.
　一般に、正極は、正極合剤を調製し、正極集電体に、正極合剤を担持させ、担持物を圧縮（または圧延）することにより得られる。本発明の実施形態では、正極合剤を調製し、正極集電体に正極合剤を充填し、得られた充填物を厚み方向に圧縮し、圧縮物を、正極の水分量が５００ｐｐｍとなるように、高温（例えば、２００℃以上で、かつ、バインダに含まれる高分子の融点および荷重たわみ温度の低い方よりも低い温度）で乾燥することにより、正極を得ることができる。正極およびキャパシタの製造方法の詳細については、後述する。 Generally, the positive electrode is obtained by preparing a positive electrode mixture, supporting the positive electrode mixture on a positive electrode current collector, and compressing (or rolling) the supported material. In the embodiment of the present invention, a positive electrode mixture is prepared, the positive electrode current collector is filled with the positive electrode mixture, the resulting filler is compressed in the thickness direction, and the moisture content of the positive electrode becomes 500 ppm. Thus, the positive electrode can be obtained by drying at a high temperature (for example, 200 ° C. or higher and lower than the lower melting point of the polymer contained in the binder and the deflection temperature under load). Details of the manufacturing method of the positive electrode and the capacitor will be described later.
　正極集電体に充填する正極合剤は、通常、正極合剤の構成成分（正極活物質、バインダ、導電助剤など）を含むスラリーの形態で使用される。正極合剤スラリーは、正極合剤の構成成分を、分散媒に分散することにより得られる。分散媒としては、例えば、水、Ｎ－メチル－２－ピロリドン（ＮＭＰ：Ｎ－ｍｅｔｈｙｌ－２－ｐｙｒｒｏｌｉｄｏｎｅ）などの有機溶媒、もしくは水と有機溶媒（エタノールなどの水溶性有機溶媒など）との混合溶媒などが用いられる。 The positive electrode mixture filled in the positive electrode current collector is usually used in the form of a slurry containing the components of the positive electrode mixture (positive electrode active material, binder, conductive additive, etc.). The positive electrode mixture slurry is obtained by dispersing the components of the positive electrode mixture in a dispersion medium. Examples of the dispersion medium include water, an organic solvent such as N-methyl-2-pyrrolidone (NMP), or a mixture of water and an organic solvent (water-soluble organic solvent such as ethanol). A solvent or the like is used.
　分散媒の種類は、バインダの種類に応じて選択することができる。例えば、セルロースエーテルなどを含むバインダを用いる場合、分散媒としては、水または水と有機溶媒との混合溶媒が用いることが好ましい。ポリイミド樹脂を含むバインダを用いる場合、分散媒としては、有機溶媒が好適に使用される。分散媒は、正極の製造過程で（スラリーを集電体に充填した後、および／または圧延した後などに）、乾燥により除去される。水を含む分散媒を用いる場合、正極の水分量が高くなり易いが、本発明の実施形態によれば、水を含む分散媒を用いる場合にも、正極の水分量を大きく低減できる。 The type of dispersion medium can be selected according to the type of binder. For example, when a binder containing cellulose ether or the like is used, it is preferable to use water or a mixed solvent of water and an organic solvent as the dispersion medium. When using a binder containing a polyimide resin, an organic solvent is preferably used as the dispersion medium. The dispersion medium is removed by drying in the process of manufacturing the positive electrode (after filling the current collector with the slurry and / or after rolling). When using a dispersion medium containing water, the moisture content of the positive electrode tends to be high, but according to the embodiment of the present invention, the moisture content of the positive electrode can be greatly reduced even when using a dispersion medium containing water.
　キャパシタは、正極に加え、負極、正極と負極との間に介在するセパレータ、および非水電解質を含む。以下、正極以外のキャパシタの構成要素についてより詳細に説明する。 The capacitor includes a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a nonaqueous electrolyte in addition to the positive electrode. Hereinafter, the components of the capacitor other than the positive electrode will be described in more detail.
　（負極）
　負極としては、キャパシタに使用される公知の負極が使用できる。具体的には、負極は、負極活物質を含む。負極活物質は、カチオンを可逆的に担持する材料を含むことが好ましい。負極活物質は、キャパシタの種類に応じて適宜選択できる。 (Negative electrode)
As a negative electrode, the well-known negative electrode used for a capacitor can be used. Specifically, the negative electrode includes a negative electrode active material. The negative electrode active material preferably includes a material that reversibly supports cations. A negative electrode active material can be suitably selected according to the kind of capacitor.
　ＥＤＬＣでは、負極活物質は、カチオンを可逆的に担持（具体的には、吸着および脱着）する材料、つまり、非ファラデー反応を起こす材料を含む。負極活物質としては、正極活物質について例示した活性炭、メソポーラスカーボンなどが使用できる。 In EDLC, the negative electrode active material includes a material that reversibly carries cations (specifically, adsorption and desorption), that is, a material that causes a non-Faraday reaction. As the negative electrode active material, activated carbon, mesoporous carbon and the like exemplified for the positive electrode active material can be used.
　ＥＤＬＣでは、しばしば活性炭が負極活物質として用いられる。活性炭を含む負極活物質を用いる場合、負極の水分量を低減し難く、キャパシタ内の水分量を低減し難い。そのため、活性炭を含む負極活物質を用いる場合には、正極の場合に準じて、水分量を低減した負極を用いることが好ましい。 In EDLC, activated carbon is often used as the negative electrode active material. When a negative electrode active material containing activated carbon is used, it is difficult to reduce the moisture content of the negative electrode, and it is difficult to reduce the moisture content in the capacitor. Therefore, when a negative electrode active material containing activated carbon is used, it is preferable to use a negative electrode with a reduced amount of water in accordance with the case of the positive electrode.
　リチウムイオンキャパシタ、ナトリウムイオンキャパシタなどのアルカリ金属イオンキャパシタでは、負極活物質は、アルカリ金属イオンを可逆的に担持（または、吸蔵および放出）する材料を含む。このような材料は、充放電の際にファラデー反応を起こすものである。 In alkali metal ion capacitors such as lithium ion capacitors and sodium ion capacitors, the negative electrode active material includes a material that reversibly carries (or occludes and releases) alkali metal ions. Such materials cause a Faraday reaction during charging and discharging.
　このような材料としては、例えば、アルカリ金属イオンを吸蔵および放出する炭素材料（第１炭素材料とも言う）の他、アルカリ金属チタン酸化物［例えば、リチウムチタン酸化物（チタン酸リチウムなどのスピネル型リチウムチタン酸化物など）、ナトリウムチタン酸化物（チタン酸ナトリウムなど）］、ケイ素酸化物、ケイ素合金、錫酸化物、錫合金が挙げられる。第１炭素材料としては、易黒鉛化性炭素（ソフトカーボン）、難黒鉛化性炭素（ハードカーボン）、黒鉛（天然黒鉛、人造黒鉛などの黒鉛型結晶構造を有する炭素質材料など）などが例示できる。負極活物質は、一種を単独で用いてもよく、二種以上を組み合わせて用いてもよい。負極活物質は、理論容量が３００ｍＡｈ／ｇ以上であるものが好ましい。負極活物質のうち、第１炭素材料が好ましく、特に、黒鉛および／またはハードカーボンが好ましい。 As such a material, for example, in addition to a carbon material that occludes and releases alkali metal ions (also referred to as a first carbon material), an alkali metal titanium oxide [for example, a spinel type such as lithium titanium oxide (lithium titanate or the like) Lithium titanium oxide etc.), sodium titanium oxide (sodium titanate etc.)], silicon oxide, silicon alloy, tin oxide and tin alloy. Examples of the first carbon material include graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), graphite (carbonaceous materials having a graphite-type crystal structure such as natural graphite and artificial graphite), and the like. it can. A negative electrode active material may be used individually by 1 type, and may be used in combination of 2 or more type. The negative electrode active material preferably has a theoretical capacity of 300 mAh / g or more. Of the negative electrode active materials, the first carbon material is preferable, and graphite and / or hard carbon is particularly preferable.
　アルカリ金属イオンキャパシタの負極活物質は、疎水性が高いため、負極の水分量を低減し易い。そのため、本発明の実施形態に係る正極は、特に、このような負極活物質を用いるアルカリ金属イオンキャパシタに適している。 Since the negative electrode active material of the alkali metal ion capacitor has high hydrophobicity, it is easy to reduce the moisture content of the negative electrode. Therefore, the positive electrode according to the embodiment of the present invention is particularly suitable for an alkali metal ion capacitor using such a negative electrode active material.
　負極は、上記のような負極活物質を含む限り特に制限されず、負極活物質と、任意成分として、バインダおよび／または導電助剤などとを含む負極合剤を含んでもよい。負極は、さらに負極集電体を含むことができ、このような負極において、負極集電体には、負極活物質、または負極合剤が担持されている。導電助剤としては、正極について例示したものから適宜選択できる。負極活物質１００質量部に対する導電助剤の量は、正極活物質１００質量部に対する導電助剤の量と同様の範囲から適宜選択できる。 The negative electrode is not particularly limited as long as it includes the negative electrode active material as described above, and may include a negative electrode mixture containing a negative electrode active material and, as an optional component, a binder and / or a conductive additive. The negative electrode can further include a negative electrode current collector. In such a negative electrode, the negative electrode current collector carries a negative electrode active material or a negative electrode mixture. As a conductive support agent, it can select suitably from what was illustrated about the positive electrode. The amount of the conductive additive relative to 100 parts by mass of the negative electrode active material can be appropriately selected from the same range as the amount of the conductive auxiliary relative to 100 parts by mass of the positive electrode active material.
　バインダの種類は特に制限されず、例えば、正極について例示したものの他、ポリフッ化ビニリデン（ＰＶＤＦ：ｐｏｌｙｖｉｎｙｌｉｄｅｎｅ　ｆｌｕｏｒｉｄｅ）などのフッ素樹脂；ポリオレフィン樹脂；スチレンブタジエンゴムなどのゴム状重合体などを用いることができる。バインダは、一種を単独でまたは二種以上を組み合わせて使用できる。バインダの量は、特に制限されないが、高い結着性および容量を確保し易い観点から、負極活物質１００質量部当たり、例えば、０．１質量部～１５質量部程度の範囲から選択でき、好ましくは０．５質量部～１０質量部である。 The type of the binder is not particularly limited. For example, in addition to those exemplified for the positive electrode, fluorine resins such as polyvinylidene fluoride (PVDF); polyolefin resins; rubbery polymers such as styrene butadiene rubber can be used. . A binder can be used individually by 1 type or in combination of 2 or more types. The amount of the binder is not particularly limited, but can be selected from a range of, for example, about 0.1 to 15 parts by mass per 100 parts by mass of the negative electrode active material, from the viewpoint of easily ensuring high binding properties and capacity. Is 0.5 to 10 parts by mass.
　負極集電体は、金属箔でもよいが、キャパシタを高容量化する観点からは、金属多孔体であることが好ましい。金属多孔体としては、正極集電体と同様の三次元網目状の骨格（特に、中空の骨格）を有するものが好ましい。金属多孔体の気孔率、平均空孔径、骨格内部の空洞の幅、比表面積などは、正極集電体について例示した範囲から適宜選択できる。 The negative electrode current collector may be a metal foil, but is preferably a metal porous body from the viewpoint of increasing the capacity of the capacitor. As the metal porous body, those having the same three-dimensional network skeleton as the positive electrode current collector (particularly, a hollow skeleton) are preferable. The porosity, average pore diameter, void width inside the skeleton, specific surface area, and the like of the metal porous body can be appropriately selected from the ranges exemplified for the positive electrode current collector.
　負極集電体の材質としては、銅、銅合金、ニッケル、ニッケル合金、ステンレス鋼などが好ましい。負極集電体は、樹脂多孔体を金属被覆する際に、アルミニウムまたはアルミニウム合金に代えて、これらの材質を用い、正極集電体の場合に準じて作製することができる。 The material of the negative electrode current collector is preferably copper, copper alloy, nickel, nickel alloy, stainless steel, or the like. The negative electrode current collector can be produced according to the case of the positive electrode current collector using these materials instead of aluminum or aluminum alloy when the resin porous body is metal-coated.
　負極は、例えば、負極集電体に、少なくとも負極活物質を担持することにより形成できる。負極は、負極活物質を含む負極合剤を塗布または充填し、圧縮（または圧延）することにより形成することもできる。適当な段階（負極合剤を塗布または充填した後、および／または圧縮した後など）で乾燥処理を行ってもよい。負極としては、負極集電体の表面に、蒸着、スパッタリングなどの気相法で負極活物質の堆積膜を形成することにより得られるものを用いてもよい。負極合剤は、正極合剤の場合と同様に、通常、負極合剤の構成成分を含むスラリーの形態で使用される。スラリーは、負極合剤の構成成分を分散媒に分散することにより得られる。分散媒としては、正極について例示したものから適宜選択できる。 The negative electrode can be formed, for example, by supporting at least a negative electrode active material on a negative electrode current collector. The negative electrode can also be formed by applying or filling a negative electrode mixture containing a negative electrode active material and compressing (or rolling). You may perform a drying process in a suitable stage (after apply | coating or filling a negative mix, and / or after compressing etc.). As the negative electrode, one obtained by forming a deposited film of a negative electrode active material on the surface of the negative electrode current collector by a vapor phase method such as vapor deposition or sputtering may be used. As in the case of the positive electrode mixture, the negative electrode mixture is usually used in the form of a slurry containing the constituent components of the negative electrode mixture. The slurry is obtained by dispersing the constituent components of the negative electrode mixture in a dispersion medium. As a dispersion medium, it can select suitably from what was illustrated about the positive electrode.
　アルカリ金属イオンキャパシタに使用する負極において、負極活物質には、リチウムイオン、ナトリウムイオンなどのアルカリ金属イオンが担持（プレドープ）されていることが望ましい。アルカリ金属イオンを負極活物質にプレドープすることで、負極の電位を十分に低くすることができ、負極の容量を大きくすることができる。アルカリ金属イオンのプレドープは公知の方法で行うことができる。アルカリ金属イオンのプレドープは、キャパシタの組み立て前に行ってもよく、キャパシタ内で行ってもよい。 In a negative electrode used for an alkali metal ion capacitor, it is desirable that alkali metal ions such as lithium ions and sodium ions are supported (pre-doped) on the negative electrode active material. By pre-doping the negative electrode active material with alkali metal ions, the potential of the negative electrode can be sufficiently lowered, and the capacity of the negative electrode can be increased. The pre-doping of alkali metal ions can be performed by a known method. The alkali metal ion pre-doping may be performed before the assembly of the capacitor, or may be performed in the capacitor.
　アルカリ金属イオンキャパシタに使用する負極では、活物質の疎水性が高いため、水分が混入し易い負極合剤を用いる場合でも、負極集電体に負極合剤を担持させた担持物を圧縮する前および／または圧縮した後に乾燥する段階で、負極の水分量を大きく低減することができる。また、ＥＤＬＣおよびアルカリ金属イオンキャパシタのいずれにおいても、正極の場合と同様に、キャパシタを製造する際に、負極の水分量をさらに低減することができる。 In the negative electrode used for an alkali metal ion capacitor, since the active material is highly hydrophobic, even when a negative electrode mixture that easily mixes moisture is used, the negative electrode current collector is loaded before compressing the support. In addition, the moisture content of the negative electrode can be greatly reduced at the stage of drying after compression. Further, in both the EDLC and the alkali metal ion capacitor, as in the case of the positive electrode, the moisture content of the negative electrode can be further reduced when the capacitor is manufactured.
　キャパシタ内において、正極は酸化側であるため、充放電により活性炭に親水性の官能基が生成して、水分を吸着し易い状態となり、副反応が起こり易くなる。そのため、正極以外のキャパシタの構成要素（例えば、負極、セパレータ、および／または電解質）の水分もできるだけ低いことが好ましい。負極の水分量は、例えば、正極の水分量と同じ範囲から選択でき、３００ｐｐｍ以下または１００ｐｐｍ以下であってもよい。負極の水分量は、正極の水分量と同じく、非水電解質と接触させる前の負極の水分量であり、正極の水分量の場合に準じて、カールフィッシャー法により測定できる。 In the capacitor, since the positive electrode is on the oxidation side, a hydrophilic functional group is generated on the activated carbon by charge / discharge, so that moisture is easily adsorbed and side reactions are likely to occur. Therefore, it is preferable that the moisture content of the capacitor other than the positive electrode (for example, the negative electrode, the separator, and / or the electrolyte) is as low as possible. The moisture content of the negative electrode can be selected from the same range as the moisture content of the positive electrode, for example, and may be 300 ppm or less or 100 ppm or less. The moisture content of the negative electrode is the moisture content of the negative electrode before being brought into contact with the non-aqueous electrolyte, similarly to the moisture content of the positive electrode, and can be measured by the Karl Fischer method according to the case of the moisture content of the positive electrode.
　負極の厚みは、例えば、５０μｍ～２０００μｍの範囲から適宜選択できる。負極集電体として三次元網目状の金属多孔体を用いる場合、負極の厚みは、例えば、１００μｍ～２０００μｍ、好ましくは１５０μｍ～２０００μｍである。 The thickness of the negative electrode can be appropriately selected from the range of 50 μm to 2000 μm, for example. When a three-dimensional network metal porous body is used as the negative electrode current collector, the thickness of the negative electrode is, for example, 100 μm to 2000 μm, preferably 150 μm to 2000 μm.
　（セパレータ）
　キャパシタに含まれるセパレータは、キャパシタの種類に応じて適宜選択できる。
　セパレータは、イオン透過性を有し、正極と負極との間に介在して、これらを物理的に離間させて短絡を防止する。セパレータは、多孔質構造を有し、細孔内に電解質を保持することで、イオンを透過させる。セパレータの材質としては、例えば、ポリエチレン、ポリプロピレンなどのポリオレフィン；ポリエチレンテレフタレートなどのポリエステル；ポリアミド；ポリイミド；セルロース；ガラス繊維などを用いることができる。
　セパレータの平均孔径は特に制限されず、例えば、０．０１μｍ～５μｍ程度である。セパレータの厚みは特に制限されず、例えば、１０μｍ～１００μｍ程度である。 (Separator)
The separator included in the capacitor can be appropriately selected according to the type of the capacitor.
The separator has ion permeability, is interposed between the positive electrode and the negative electrode, and physically separates them to prevent a short circuit. The separator has a porous structure and allows ions to pass through by holding an electrolyte in the pores. As a material of the separator, for example, polyolefin such as polyethylene and polypropylene; polyester such as polyethylene terephthalate; polyamide; polyimide; cellulose; glass fiber and the like can be used.
The average pore diameter of the separator is not particularly limited and is, for example, about 0.01 μm to 5 μm. The thickness of the separator is not particularly limited and is, for example, about 10 μm to 100 μm.
　セパレータは、電極群を組み立てる際に、乾燥させて、水分量を低減させることが好ましい。セパレータの水分量は、電極群を形成する前の段階で、４００ｐｐｍ以下であることが好ましく、２５０ｐｐｍ以下であることがさらに好ましい。このセパレータの水分量は、正極の場合と同じく非水電解質と接触させる前のセパレータの水分量であり、正極の場合に準じて、カールフィッシャー法により測定できる。 The separator is preferably dried when assembling the electrode group to reduce the amount of water. The moisture content of the separator is preferably 400 ppm or less, and more preferably 250 ppm or less, before the electrode group is formed. The moisture content of this separator is the moisture content of the separator before contacting with the non-aqueous electrolyte as in the case of the positive electrode, and can be measured by the Karl Fischer method according to the case of the positive electrode.
　（非水電解質）
　非水電解質は、キャパシタの種類に応じて選択できる。非水電解質は、カチオンおよびアニオンを含む。
　非水電解質は、キャパシタに注液する前に、水分量を低減させておくことが好ましい。非水電解質の水分量は、原料となる媒体（具体的には、後述の有機溶媒およびイオン液体）、および／または溶質（アルカリ金属塩など）を脱水することにより低減できる。また、乾燥雰囲気下で、非水電解質を調製することが好ましい。媒体および溶質の脱水は公知の方法で行うことができる。非水電解質についても、正極の場合と同様に、キャパシタを製造する際に、水分量をさらに低減することができる。 (Nonaqueous electrolyte)
The nonaqueous electrolyte can be selected according to the type of capacitor. The non-aqueous electrolyte includes a cation and an anion.
The non-aqueous electrolyte is preferably reduced in water content before being injected into the capacitor. The water content of the non-aqueous electrolyte can be reduced by dehydrating a medium (specifically, an organic solvent and an ionic liquid described later) and / or a solute (such as an alkali metal salt) as a raw material. Moreover, it is preferable to prepare a non-aqueous electrolyte in a dry atmosphere. The dehydration of the medium and the solute can be performed by a known method. As for the non-aqueous electrolyte, as in the case of the positive electrode, the moisture content can be further reduced when the capacitor is manufactured.
　非水電解質の水分量は、例えば、２００ｐｐｍ以下であることが好ましく、１００ｐｐｍ以下または５０ｐｐｍ以下であることがさらに好ましい。非水電解質の水分量は、セルケースに非水電解質を収容する前のものであり、正極の場合に準じて、カールフィッシャー法により測定できる。 The water content of the nonaqueous electrolyte is, for example, preferably 200 ppm or less, and more preferably 100 ppm or less or 50 ppm or less. The water content of the non-aqueous electrolyte is before the non-aqueous electrolyte is accommodated in the cell case, and can be measured by the Karl Fischer method according to the case of the positive electrode.
　（アルカリ金属イオンキャパシタ用非水電解質）
　アルカリ金属イオンキャパシタでは、アルカリ金属イオン伝導性を有する非水電解質が使用される。このような非水電解質は、アルカリ金属イオンを含むカチオンとアニオンとを含む。非水電解質としては、例えば、非水溶媒（または有機溶媒）にアルカリ金属イオンとアニオンとの塩（アルカリ金属塩）を溶解させた電解質（有機電解質）の他、アルカリ金属イオンを含むカチオンとアニオンとを含むイオン液体などが用いられる。 (Nonaqueous electrolyte for alkali metal ion capacitors)
In the alkali metal ion capacitor, a non-aqueous electrolyte having alkali metal ion conductivity is used. Such a non-aqueous electrolyte contains a cation containing an alkali metal ion and an anion. Nonaqueous electrolytes include, for example, an electrolyte (organic electrolyte) in which a salt of an alkali metal ion and an anion (alkali metal salt) is dissolved in a nonaqueous solvent (or an organic solvent), and a cation and an anion containing an alkali metal ion. An ionic liquid containing or the like is used.
　有機電解質は、非水溶媒（有機溶媒）およびアルカリ金属塩に加え、イオン液体および／または添加剤などを含むことができる。ただし、電解質中の非水溶媒およびリチウム塩の含有量の合計は、例えば、６０質量％～１００質量％、好ましくは７５質量％～１００質量％、または８５質量％～１００質量％である。電解質中の非水溶媒およびリチウム塩の含有量の合計は、例えば、９５質量％以下であってもよい。 The organic electrolyte can contain an ionic liquid and / or an additive in addition to the non-aqueous solvent (organic solvent) and the alkali metal salt. However, the total content of the nonaqueous solvent and the lithium salt in the electrolyte is, for example, 60% by mass to 100% by mass, preferably 75% by mass to 100% by mass, or 85% by mass to 100% by mass. The total content of the nonaqueous solvent and the lithium salt in the electrolyte may be, for example, 95% by mass or less.
　本明細書中、イオン液体は、溶融状態の塩（溶融塩）と同義であり、アニオンとカチオンとで構成される液状イオン性物質である。
　電解質にイオン液体を用いる場合、電解質は、アルカリ金属イオンを含むカチオンとアニオンとを含むイオン液体に加え、非水溶媒および／または添加剤などを含むことができる。ただし、電解質中のイオン液体の含有量は、６０質量％～１００質量％であることが好ましく、８０質量％～１００質量％または９０質量％～１００質量％であってもよい。 In this specification, an ionic liquid is synonymous with a salt (molten salt) in a molten state, and is a liquid ionic substance composed of an anion and a cation.
When an ionic liquid is used for the electrolyte, the electrolyte can contain a nonaqueous solvent and / or an additive in addition to the ionic liquid containing a cation containing an alkali metal ion and an anion. However, the content of the ionic liquid in the electrolyte is preferably 60% by mass to 100% by mass, and may be 80% by mass to 100% by mass or 90% by mass to 100% by mass.
　低温特性などの観点からは、有機溶媒を含む電解質を用いることが好ましい。電解質の分解をできるだけ抑制する観点からは、イオン液体を含む電解質を用いることが好ましく、イオン液体および有機溶媒を含む電解質を用いてもよい。
　電解質におけるアルカリ金属塩またはアルカリ金属イオンの濃度は、例えば、０．３ｍｏｌ／Ｌ～５ｍｏｌ／Ｌの範囲から適宜選択できる。 From the viewpoint of low temperature characteristics and the like, it is preferable to use an electrolyte containing an organic solvent. From the viewpoint of suppressing the decomposition of the electrolyte as much as possible, an electrolyte containing an ionic liquid is preferably used, and an electrolyte containing an ionic liquid and an organic solvent may be used.
The concentration of the alkali metal salt or alkali metal ion in the electrolyte can be appropriately selected from the range of 0.3 mol / L to 5 mol / L, for example.
　アルカリ金属イオンとしては、例えば、リチウムイオン、ナトリウムイオン、カリウムイオン、ルビジウムイオン、およびセシウムイオンからなる群より選択される少なくとも一種が挙げられる。これらのうち、リチウムイオンおよびナトリウムイオンからなる群より選択される少なくとも一種が好ましい。これらのアルカリ金属イオンを用いることで、アルカリ金属イオンを、充電時にはスムーズに負極活物質に吸蔵させることができるとともに、放電時には負極活物質から放出させることができる。 Examples of the alkali metal ions include at least one selected from the group consisting of lithium ions, sodium ions, potassium ions, rubidium ions, and cesium ions. Of these, at least one selected from the group consisting of lithium ions and sodium ions is preferred. By using these alkali metal ions, the alkali metal ions can be smoothly occluded in the negative electrode active material during charging, and can be released from the negative electrode active material during discharge.
　リチウムイオン伝導性を有する電解質を用いるアルカリ金属イオンキャパシタは、リチウムイオンキャパシタとも称される。また、ナトリウムイオン伝導性を有する電解質を用いるアルカリ金属イオンキャパシタは、ナトリウムイオンキャパシタとも称される。 An alkali metal ion capacitor using an electrolyte having lithium ion conductivity is also referred to as a lithium ion capacitor. An alkali metal ion capacitor using an electrolyte having sodium ion conductivity is also referred to as a sodium ion capacitor.
　アルカリ金属塩を構成するアニオン（第１アニオン）の種類は特に限定されず、例えば、フッ素含有酸のアニオン［ヘキサフルオロリン酸イオンなどのフッ素含有リン酸のアニオン；テトラフルオロホウ酸イオンなどのフッ素含有ホウ酸のアニオンなど］、塩素含有酸のアニオン［過塩素酸イオンなど］、オキサレート基を有する酸素酸のアニオン［ビス（オキサラト）ボレートイオン（Ｂ（Ｃ2Ｏ4）2 -）などのオキサラトボレートイオン；トリス（オキサラト）ホスフェートイオン（Ｐ（Ｃ2Ｏ4）3 -）などのオキサラトホスフェートイオンなど］、フルオロアルカンスルホン酸のアニオン［トリフルオロメタンスルホン酸イオン（ＣＦ3ＳＯ3 -）など］、ビススルホニルアミドアニオンなどが挙げられる。
　アルカリ金属塩は、一種を単独で用いてもよく、第１アニオンの種類が異なるアルカリ金属塩を二種以上組み合わせて用いてもよい。 The kind of anion (first anion) constituting the alkali metal salt is not particularly limited. For example, an anion of a fluorine-containing acid [anion of fluorine-containing phosphate such as hexafluorophosphate ion; fluorine such as tetrafluoroborate ion; Oxides such as anions of boric acid containing], anions of chlorine containing acids [such as perchlorate ions], anions of oxygen acids having oxalate groups [bis (oxalato) borate ions (B (C 2 O 4 ) 2 − )] Latoborate ion; Oxalatophosphate ion such as tris (oxalato) phosphate ion (P (C 2 O 4 ) 3 − ), anion of fluoroalkanesulfonic acid [trifluoromethanesulfonic acid ion (CF 3 SO 3 − ), etc. ], Bissulfonylamide anion, etc. are mentioned.
One alkali metal salt may be used alone, or two or more alkali metal salts having different types of first anions may be used in combination.
　上記のビススルホニルアミドアニオンとしては、例えば、ビス（フルオロスルホニル）アミドアニオン（ＦＳＡ-：ｂｉｓ（ｆｌｕｏｒｏｓｕｌｆｏｎｙｌ）ａｍｉｄｅ　ａｎｉｏｎ））、ビス（トリフルオロメチルスルホニル）アミドアニオン（ＴＦＳＡ-：ｂｉｓ（ｔｒｉｆｌｕｏｒｏｍｅｔｈｙｌｓｕｌｆｏｎｙｌ）ａｍｉｄｅ　ａｎｉｏｎ）、（フルオロスルホニル）（パーフルオロアルキルスルホニル）アミドアニオン［（ＦＳＯ2）（ＣＦ3ＳＯ2）Ｎ-など］、ビス（パーフルオロアルキルスルホニル）アミドアニオン［Ｎ（ＳＯ2ＣＦ3）2 -、Ｎ（ＳＯ2Ｃ2Ｆ5）2 -など］などが挙げられる。これらの中では、ＦＳＡ-が好ましい。 Examples of the bissulfonylamide anion include bis (fluorosulfonyl) amide anion (FSA − : bis (fluorosulfonyl) amide anion), bis (trifluoromethylsulfonyl) amide anion (TFSA − : bis (trifluoromethylsulfamide) amide anion. ), (Fluorosulfonyl) (perfluoroalkylsulfonyl) amide anion [(FSO 2 ) (CF 3 SO 2 ) N − etc.], bis (perfluoroalkylsulfonyl) amide anion [N (SO 2 CF 3 ) 2 − , N (SO 2 C 2 F 5 ) 2 — and the like]. Of these, FSA - is preferred.
　非水溶媒は、特に限定されず、リチウムイオンキャパシタに使用される公知の非水溶媒が使用できる。非水溶媒は、イオン伝導度の観点から、例えば、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネートなどの環状カーボネート；ジメチルカーボネート、ジエチルカーボネート、エチルメチルカーボネートなどの鎖状カーボネート；γ－ブチロラクトンなどの環状炭酸エステルなどを好ましく用いることができる。非水溶媒は、一種を単独で用いてもよく、二種以上を組み合わせて用いてもよい。 The non-aqueous solvent is not particularly limited, and a known non-aqueous solvent used for a lithium ion capacitor can be used. Non-aqueous solvents include, for example, cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; cyclic carbonates such as γ-butyrolactone. Etc. can be preferably used. A non-aqueous solvent may be used individually by 1 type, and may be used in combination of 2 or more type.
　イオン液体は、カチオンとアニオン（第２アニオン）との溶融塩を含む。イオン液体は、一種の溶融塩を含んでもよく、カチオンおよび／または第２アニオンの種類が異なる二種以上の溶融塩を含んでもよい。
　第２アニオンとしては、ビススルホニルアミドアニオンを用いることが好ましい。ビススルホニルアミドアニオンとしては、第１アニオンについて例示したものと同様のものから選択できる。 The ionic liquid contains a molten salt of a cation and an anion (second anion). The ionic liquid may contain a kind of molten salt, or may contain two or more kinds of molten salts having different types of cations and / or second anions.
As the second anion, a bissulfonylamide anion is preferably used. The bissulfonylamide anion can be selected from those similar to those exemplified for the first anion.
　イオン液体を構成するカチオンは、少なくともアルカリ金属イオンを含み、アルカリ金属イオン（第１カチオン）と第２カチオンとを含んでもよい。
　第２カチオンとしては、アルカリ金属イオンとは異なる無機カチオン、有機カチオンなどが例示できる。無機カチオンとしては、例えば、アルカリ土類金属イオン（マグネシウムイオン、カルシウムイオンなど）、アンモニウムイオンなどが挙げられる。第２カチオンは、無機カチオンであってもよいが、有機カチオンであることが好ましい。イオン液体は、第２カチオンを、一種含んでもよく、二種以上組合せて含んでもよい。 The cation constituting the ionic liquid contains at least an alkali metal ion, and may contain an alkali metal ion (first cation) and a second cation.
Examples of the second cation include an inorganic cation and an organic cation different from the alkali metal ion. Examples of the inorganic cation include alkaline earth metal ions (magnesium ions, calcium ions, etc.), ammonium ions, and the like. The second cation may be an inorganic cation, but is preferably an organic cation. The ionic liquid may contain one type of second cation, or may contain two or more types in combination.
　有機カチオンとしては、脂肪族アミン、脂環族アミンまたは芳香族アミンに由来するカチオン（例えば、第４級アンモニウムカチオンなど）の他、窒素含有へテロ環を有するカチオン（つまり、環状アミンに由来するカチオン）などの窒素含有オニウムカチオン；イオウ含有オニウムカチオン；リン含有オニウムカチオンなどが例示できる。
　窒素含有有機オニウムカチオンのうち、特に、第４級アンモニウムカチオンの他、窒素含有ヘテロ環骨格として、ピロリジン、ピリジン、またはイミダゾール骨格を有するものが好ましい。 Organic cations include cations derived from aliphatic amines, alicyclic amines or aromatic amines (for example, quaternary ammonium cations), as well as cations having nitrogen-containing heterocycles (that is, derived from cyclic amines). Examples thereof include nitrogen-containing onium cations such as cations); sulfur-containing onium cations; and phosphorus-containing onium cations.
Of the nitrogen-containing organic onium cations, those having a pyrrolidine, pyridine, or imidazole skeleton as the nitrogen-containing heterocyclic skeleton in addition to the quaternary ammonium cation are particularly preferable.
　窒素含有有機オニウムカチオンの具体例としては、テトラエチルアンモニウムカチオン（ＴＥＡ+：ｔｅｔｒａｅｔｈｙｌａｍｍｏｎｉｕｍ　ｃａｔｉｏｎ）、メチルトリエチルアンモニウムカチオン（ＴＥＭＡ+：ｍｅｔｈｙｌｔｒｉｅｔｈｙｌａｍｍｏｎｉｕｍ　ｃａｔｉｏｎ）などのテトラアルキルアンモニウムカチオン；１－メチル－１－プロピルピロリジニウムカチオン（ＭＰＰＹ+：１－ｍｅｔｈｙｌ－１－ｐｒｏｐｙｌｐｙｒｒｏｌｉｄｉｎｉｕｍ　ｃａｔｉｏｎ）、１－ブチル－１－メチルピロリジニウムカチオン（ＭＢＰＹ+：１－ｂｕｔｙｌ－１－ｍｅｔｈｙｌｐｙｒｒｏｌｉｄｉｎｉｕｍ　ｃａｔｉｏｎ）；１－エチル－３－メチルイミダゾリウムカチオン（ＥＭＩ+：　１－ｅｔｈｙｌ－３－ｍｅｔｈｙｌｉｍｉｄａｚｏｌｉｕｍ　ｃａｔｉｏｎ）、１－ブチル－３－メチルイミダゾリウムカチオン（ＢＭＩ+：１－ｂｕｔｈｙｌ－３－ｍｅｔｈｙｌｉｍｉｄａｚｏｌｉｕｍ　ｃａｔｉｏｎ）などが挙げられる。 Specific examples of nitrogen-containing organic onium cations include tetraalkylammonium cations (TEA + : tetraethylammonium cation), tetraalkylammonium cations such as methyltriethylammonium cation (TEMA + : methyltriethylammonium cation); 1-methyl-1-propylpyrrolidinium Cations (MPPY + : 1-methyl-1-propylpyrrolidinium cation), 1-butyl-1-methylpyrrolidinium cation (MBPY + : 1-butyl-1-methylpyrrolidinium cation); 1-ethyl-3-methylimidazolium cation (EMI +: 1-ethyl- 3-methylimidazo ium cation), 1- butyl-3-methylimidazolium cation (BMI +: 1-buthyl- 3-methylimidazolium cation) and the like.
　（ＥＤＬＣ用非水電解質）
　ＥＤＬＣに使用される非水電解質としては、カチオン（第３カチオン）とアニオン（第３アニオン）との塩を非水溶媒（または有機溶媒）に溶解させた電解質の他、カチオン（第４カチオン）およびアニオン（第４アニオン）を含むイオン液体などの非水電解質が好ましく用いられる。
　第３および第４カチオンとしては、それぞれ、アルカリ金属イオンキャパシタの非水電解質について例示した無機カチオン（アルカリ金属イオン、アルカリ土類金属イオン、アンモニウムイオンなど）および有機カチオンなどが例示できる。
　電解質におけるカチオンの濃度は、例えば、０．３ｍｏｌ／Ｌ～５ｍｏｌ／Ｌの範囲から適宜選択できる。 (Non-aqueous electrolyte for EDLC)
Nonaqueous electrolytes used in EDLC include electrolytes in which a salt of a cation (third cation) and an anion (third anion) is dissolved in a nonaqueous solvent (or organic solvent), as well as a cation (fourth cation). And a non-aqueous electrolyte such as an ionic liquid containing an anion (fourth anion) is preferably used.
Examples of the third and fourth cations include inorganic cations (alkali metal ions, alkaline earth metal ions, ammonium ions, etc.) and organic cations exemplified for the non-aqueous electrolyte of the alkali metal ion capacitor.
The concentration of the cation in the electrolyte can be appropriately selected from a range of 0.3 mol / L to 5 mol / L, for example.
　第３アニオンとしては、アルカリ金属イオンキャパシタの第１アニオンとして例示したものから適宜選択できる。非水溶媒としては、アルカリ金属イオンキャパシタについて例示したものから適宜選択できる。
　イオン液体に含まれる第４アニオンとしては、アルカリ金属イオンキャパシタの第２アニオンとして例示したものから適宜選択できる。第４アニオンは、少なくともビススルホニルアミドアニオンを含むことが好ましい。第４アニオン中のビススルホニルアミドアニオンの含有量は、第２アニオンの場合と同様の範囲から選択できる。 The third anion can be appropriately selected from those exemplified as the first anion of the alkali metal ion capacitor. As a nonaqueous solvent, it can select suitably from what was illustrated about the alkali metal ion capacitor.
The fourth anion contained in the ionic liquid can be appropriately selected from those exemplified as the second anion of the alkali metal ion capacitor. The fourth anion preferably includes at least a bissulfonylamide anion. The content of the bissulfonylamide anion in the fourth anion can be selected from the same range as in the case of the second anion.
　電解質中のイオン液体の含有量は、アルカリ金属イオンキャパシタについて例示した範囲から適宜選択できる。アルカリ金属イオンキャパシタの場合と同様に、電解質の分解を抑制する観点からは、イオン液体を含む電解質を用いることが好ましく、イオン液体および有機溶媒を含む電解質を用いてもよい。 The content of the ionic liquid in the electrolyte can be appropriately selected from the range exemplified for the alkali metal ion capacitor. As in the case of the alkali metal ion capacitor, from the viewpoint of suppressing the decomposition of the electrolyte, an electrolyte containing an ionic liquid is preferably used, and an electrolyte containing an ionic liquid and an organic solvent may be used.
　（キャパシタの製造方法）
　本発明の実施形態に係るキャパシタは、（ａ）正極を準備する工程、（ｂ）正極と、負極と、正極および負極の間に介在するセパレータとで電極群を形成する工程、ならびに（ｃ）電極群および非水電解質をセルケース内に収容する工程を経ることにより製造できる。工程（ｃ）の後、さらに活性化工程（ｄ）を行ってもよい。活性化工程（ｄ）を行うと、キャパシタ内の水分量をさらに低減することができる。 (Capacitor manufacturing method)
A capacitor according to an embodiment of the present invention includes (a) a step of preparing a positive electrode, (b) a step of forming an electrode group with a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and (c) It can manufacture by passing through the process of accommodating an electrode group and a nonaqueous electrolyte in a cell case. After the step (c), an activation step (d) may be further performed. When the activation step (d) is performed, the amount of moisture in the capacitor can be further reduced.
　工程（ａ）は、正極合剤を調製する工程（ａ１）、正極合剤を正極集電体に充填する工程（ａ２）、工程（ａ２）で得られた充填物を厚み方向に圧縮（または圧延）する工程（ａ３）、および工程（ａ３）で得られた圧縮物を乾燥する工程（ａ４）を含む。正極の水分量を低減する観点から、工程（ａ）を乾燥雰囲気下で行ってもよいし、工程（ａ１）、工程（ａ２）および／または工程（ａ３）を乾燥雰囲気下で行ってもよい。工程（ａ１）に使用される材料（正極合剤の構成成分）としては、乾燥したものを用いることが好ましい。 In step (a), the step (a1) for preparing the positive electrode mixture, the step (a2) for filling the positive electrode current collector with the positive electrode mixture, and the packing obtained in the step (a2) are compressed in the thickness direction (or Rolling) and a step (a4) of drying the compressed product obtained in the step (a3). From the viewpoint of reducing the moisture content of the positive electrode, the step (a) may be performed in a dry atmosphere, and the step (a1), the step (a2) and / or the step (a3) may be performed in a dry atmosphere. . As a material (component of the positive electrode mixture) used in the step (a1), it is preferable to use a dried material.
　工程（ａ３）では、圧縮に先立って、工程（ａ２）で得られた充填物を、乾燥（予備乾燥）してもよい。予備乾燥は、大気雰囲気中で行ってもよく、減圧下で行ってもよい。予備乾燥の温度は、特に制限されないが、例えば、６０℃～１５０℃または８０℃～１２０℃であってもよい。予備乾燥の乾燥時間は、特に制限されず、例えば、０．５時間～６時間でまたは０．５時間～３時間であってもよい。 In step (a3), the packing obtained in step (a2) may be dried (preliminarily dried) prior to compression. The preliminary drying may be performed in an air atmosphere or under reduced pressure. The temperature of the preliminary drying is not particularly limited, but may be, for example, 60 ° C. to 150 ° C. or 80 ° C. to 120 ° C. The drying time for the preliminary drying is not particularly limited, and may be, for example, 0.5 to 6 hours or 0.5 to 3 hours.
　工程（ａ３）の圧縮は、非水電解質と接触させる前に正極の水分量が増加しないように、乾燥雰囲気下で行ってもよい。圧縮は、例えば、露点温度が－５０℃以下または－６０℃以下の雰囲気下で行ってもよい。 Compressing in the step (a3) may be performed in a dry atmosphere so that the moisture content of the positive electrode does not increase before contacting with the non-aqueous electrolyte. The compression may be performed, for example, in an atmosphere having a dew point temperature of −50 ° C. or lower or −60 ° C. or lower.
　工程（ａ４）では、工程（ａ３）で得られた圧縮物を高温で乾燥させることにより、正極中の水分量を低減させる。工程（ａ４）における乾燥温度は、２００℃以上であり、２２０℃以上であってもよい。このような温度で乾燥を行うことにより、電極群を組み立てた後、非水電解質と接触させる前の正極中の水分量を、上述の範囲に低減できる。結着性を確保し易く、抵抗の増加を抑制し易い観点から、乾燥温度は、バインダに含まれる高分子の融点および荷重たわみ温度の低い方よりも低い温度であることが望ましい。 In step (a4), the amount of water in the positive electrode is reduced by drying the compressed product obtained in step (a3) at a high temperature. The drying temperature in the step (a4) is 200 ° C. or higher, and may be 220 ° C. or higher. By drying at such a temperature, the amount of water in the positive electrode after assembling the electrode group and before contacting with the non-aqueous electrolyte can be reduced to the above range. From the viewpoint of easily securing the binding property and suppressing the increase in resistance, the drying temperature is preferably lower than the lower one of the melting point and the deflection temperature under load of the polymer contained in the binder.
　工程（ａ４）の乾燥は、熱風乾燥および／または遠赤外線乾燥などを利用して行うことができる。また、乾燥は、常圧下で行ってもよく、減圧下で行ってもよい。複数の乾燥法を適宜組み合わせることもでき、例えば、減圧下で、遠赤外線を利用して乾燥させてもよい。正極の表面だけでなく、内部までより均一に乾燥させる観点からは、工程（ａ４）の乾燥を、減圧下、遠赤外線下、または減圧下および遠赤外線下で行ってもよい。
　工程（ａ４）の乾燥時間は、例えば、３時間～４８時間であり、６時間～２４時間または８時間～１６時間であってもよい。 The drying in the step (a4) can be performed using hot air drying and / or far infrared drying. In addition, drying may be performed under normal pressure or under reduced pressure. A plurality of drying methods can be appropriately combined. For example, drying may be performed using far infrared rays under reduced pressure. From the viewpoint of more uniformly drying not only the surface of the positive electrode but also the inside thereof, the drying in the step (a4) may be performed under reduced pressure, far infrared rays, or reduced pressure and far infrared rays.
The drying time in step (a4) is, for example, 3 hours to 48 hours, and may be 6 hours to 24 hours or 8 hours to 16 hours.
　工程（ｂ）において、電極群は、正極と負極とをセパレータを介して積層させることにより形成してもよく、正極と負極とをセパレータを介して捲回することにより形成してもよい。電極群の形成には、公知の方法が採用できる。
　非水電解質と接触させる前に正極の水分量が増加しないように、工程（ｂ）を、乾燥雰囲気下で行うことが好ましい。工程（ｂ）は、露点温度が－５０℃以下または－６０℃以下の雰囲気下で行ってもよい。また、キャパシタ内の水分量をできるだけ低減するため、工程（ｃ）も乾燥雰囲気下で行うことが好ましい。 In the step (b), the electrode group may be formed by laminating the positive electrode and the negative electrode via a separator, or may be formed by winding the positive electrode and the negative electrode via a separator. A well-known method can be employ | adopted for formation of an electrode group.
It is preferable to perform step (b) in a dry atmosphere so that the moisture content of the positive electrode does not increase before being brought into contact with the nonaqueous electrolyte. Step (b) may be performed in an atmosphere having a dew point temperature of −50 ° C. or lower or −60 ° C. or lower. In order to reduce the amount of moisture in the capacitor as much as possible, it is preferable that step (c) is also performed in a dry atmosphere.
　工程（ｃ）で組み立てたキャパシタは、通常、活性化処理工程（ｄ）に供される。活性化処理工程（ｄ）では、キャパシタは、エージング処理（または加熱処理）され、安定した充放電を可能にするために慣らし充放電される。エージング処理および／または慣らし充放電を行うことにより、キャパシタ内には、ガスが発生するため、工程（ｄ）において、ガス抜き処理を行われる。キャパシタ内において、負極活物質にアルカリ金属イオンをプレドープする場合、エージング処理は、プレドープ後に行われる。工程（ｄ）は、プレドープ工程、エージング処理工程、慣らし充放電工程、およびガス抜き工程を含むことができる。 The capacitor assembled in step (c) is usually subjected to an activation treatment step (d). In the activation treatment step (d), the capacitor is subjected to aging treatment (or heat treatment), and charged and discharged in order to enable stable charge and discharge. By performing aging treatment and / or break-in charge / discharge, gas is generated in the capacitor. Therefore, in step (d), degassing treatment is performed. In the capacitor, when alkali metal ions are pre-doped on the negative electrode active material, the aging treatment is performed after pre-doping. Step (d) can include a pre-doping step, an aging treatment step, a break-in charge / discharge step, and a degassing step.
　正極集電体への副生物の堆積は、エージング処理を行う際に特に顕著に起こる。そのため、副生物の堆積を抑制するには、工程（ｃ）よりも前の段階で、正極の水分量を十分に低減しておくことが好ましい。本発明の実施形態によれば、工程（ａ４）により、キャパシタの組み立てに供する正極の水分量を上述の範囲に低減することで、エージング処理時の副生物の堆積を抑制することができる。 The deposition of by-products on the positive electrode current collector is particularly noticeable when performing an aging treatment. Therefore, in order to suppress the accumulation of by-products, it is preferable to sufficiently reduce the moisture content of the positive electrode in the stage before step (c). According to the embodiment of the present invention, by the step (a4), by reducing the moisture content of the positive electrode used for assembling the capacitor to the above range, it is possible to suppress the accumulation of by-products during the aging process.
　工程（ｄ）において、エージング処理は、例えば、１０℃～６０℃で行うことが好ましく、２０℃～４０℃で行うことがさらに好ましい。
　ガス抜き処理は、キャパシタ内に発生したガスを、キャパシタケースに設けた弁（ガス抜き弁、後述の安全弁など）からキャパシタ外に排出することにより行うことができる。 In the step (d), the aging treatment is preferably performed at, for example, 10 ° C. to 60 ° C., more preferably 20 ° C. to 40 ° C.
The degassing process can be performed by discharging the gas generated in the capacitor out of the capacitor from a valve (a degassing valve, a safety valve described later) provided in the capacitor case.
　図１に、本発明の一実施形態に係る製造方法により得られるキャパシタ（リチウムイオンキャパシタ）の外観を斜視図により示す。図２は、図１のキャパシタを正面から見たときの内部構造を示す一部断面図である。図３は、図２のキャパシタの内部構造の一部を示す、図２のＩＩＩ－ＩＩＩ線による矢示断面図である。 FIG. 1 is a perspective view showing an external appearance of a capacitor (lithium ion capacitor) obtained by a manufacturing method according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view showing the internal structure when the capacitor of FIG. 1 is viewed from the front. 3 is a cross-sectional view taken along line III-III in FIG. 2, showing a part of the internal structure of the capacitor in FIG.
　キャパシタ（リチウムイオンキャパシタ）１０は、電極群１２および非水電解質（図示せず）と、これらを収容するセルケースとを備えている。セルケースは、ケース本体１４と、ケース本体１４の開口端部を封口する封口板１６とを含む。図示例では、セルケースは角形である。 The capacitor (lithium ion capacitor) 10 includes an electrode group 12, a non-aqueous electrolyte (not shown), and a cell case that houses them. The cell case includes a case body 14 and a sealing plate 16 that seals the open end of the case body 14. In the illustrated example, the cell case has a square shape.
　電極群１２は、シート状の複数の正極１８と、シート状の複数の負極２０とを含んでいる。正極１８と負極２０とは、セパレータ２１を間に挟んで、交互に積層されている。セパレータ２１は、正極１８を内部に収容するように袋状に形成されているが、セパレータの形状は特に限定されない。正極１８は、正極集電体２２と、正極活物質とを含む。負極２０は、負極集電体２４と、負極活物質とを含む。なお、図３では、電極と集電体とを区別して示すことが困難であるため、同一要素により電極と集電体とを示す。 The electrode group 12 includes a plurality of sheet-like positive electrodes 18 and a plurality of sheet-like negative electrodes 20. The positive electrode 18 and the negative electrode 20 are alternately stacked with the separator 21 interposed therebetween. The separator 21 is formed in a bag shape so as to accommodate the positive electrode 18 therein, but the shape of the separator is not particularly limited. The positive electrode 18 includes a positive electrode current collector 22 and a positive electrode active material. The negative electrode 20 includes a negative electrode current collector 24 and a negative electrode active material. In FIG. 3, it is difficult to distinguish between the electrode and the current collector, and therefore, the electrode and the current collector are indicated by the same element.
　封口板１６は、複数の正極１８と電気的に接続された正極外部端子４０と、複数の負極２０と電気的に接続された負極外部端子４２とを有している。封口板１６の中央部には、安全弁４４が設けられている。また、封口板１６には、安全弁４４を中心にして、正極外部端子４０寄りの位置に、注液孔を塞ぐ液栓４８が取り付けられている。 The sealing plate 16 has a positive external terminal 40 electrically connected to the plurality of positive electrodes 18 and a negative external terminal 42 electrically connected to the plurality of negative electrodes 20. A safety valve 44 is provided at the center of the sealing plate 16. Further, a liquid stopper 48 that closes the liquid injection hole is attached to the sealing plate 16 at a position near the positive electrode external terminal 40 with the safety valve 44 as the center.
　電極群１２において、正極集電体２２は、タブ状の正極接続部２６を有し、負極集電体２４は、タブ状の負極接続部２８を有している。図１に示すように、正極接続部２６は、正極外部端子４０寄りの位置に形成され、負極接続部２８は、負極外部端子４２寄りの位置に形成されている。各接続部は、集電体と同じ材質で、集電体と一体に形成することが好ましい。 In the electrode group 12, the positive electrode current collector 22 has a tab-shaped positive electrode connection portion 26, and the negative electrode current collector 24 has a tab-shaped negative electrode connection portion 28. As shown in FIG. 1, the positive electrode connection portion 26 is formed at a position near the positive electrode external terminal 40, and the negative electrode connection portion 28 is formed at a position near the negative electrode external terminal 42. Each connecting portion is preferably made of the same material as the current collector and formed integrally with the current collector.
　隣接する正極接続部２６の間には、第１導電性スペーサ３０が配されている。同様に、隣接する負極接続部２８の間にも、第２導電性スペーサが配される。第１導電性スペーサ３０および第２導電性スペーサは、それぞれ、導体（例えば、金属、炭素材料）を含む板状の部材で形成できる。ただし、第１導電性スペーサ３０は、正極接続部２６との密着性を高めるために、金属多孔体で形成することが好ましく、特に、正極集電体２２と同じ材料（例えば、アルミニウムまたはアルミニウム合金を含む三次元網目状の骨格を有する金属多孔体）で形成することが好ましい。そして、第２導電性スペーサも、第１導電性スペーサ３０の場合と同様に金属多孔体で形成することが好ましく、特に、負極集電体２４と同じ材料（例えば、銅または銅合金を含む三次元網目状の骨格を有する金属多孔体）で形成することが好ましい。 A first conductive spacer 30 is disposed between the adjacent positive electrode connection portions 26. Similarly, a second conductive spacer is disposed between adjacent negative electrode connection portions 28. The first conductive spacer 30 and the second conductive spacer can each be formed of a plate-like member including a conductor (for example, a metal or a carbon material). However, the first conductive spacer 30 is preferably formed of a metal porous body in order to improve the adhesion with the positive electrode connection portion 26, and in particular, the same material as the positive electrode current collector 22 (for example, aluminum or aluminum alloy). It is preferable to form a porous metal body having a three-dimensional network skeleton containing The second conductive spacer is also preferably formed of a metal porous body as in the case of the first conductive spacer 30, and in particular, the same material as the negative electrode current collector 24 (for example, tertiary including copper or copper alloy). It is preferably formed of a metal porous body having an original network-like skeleton.
　図示例では、正極１８の正極接続部２６には、第１締結部材（リベット）３４を挿通するための貫通孔３６が設けられている。また、第１導電性スペーサ３０にも、正極接続部２６の貫通孔３６と重なる位置に、第１締結部材３４を挿通するための貫通孔３７が設けられている。また、正極１８の場合と同様に、負極２０の負極接続部２８にも、第２締結部材（リベット）を挿通するための貫通孔が設けられている。第２導電性スペーサにも、負極接続部２８の貫通孔と重なる位置に、第２締結部材を挿通するための貫通孔が設けられている。各接続部および各導電性スペーサにおいて、貫通孔は２個ずつ設けられているが、貫通孔の個数は特に限定されない。 In the illustrated example, the positive electrode connection portion 26 of the positive electrode 18 is provided with a through hole 36 for inserting a first fastening member (rivet) 34. The first conductive spacer 30 is also provided with a through hole 37 for inserting the first fastening member 34 at a position overlapping the through hole 36 of the positive electrode connecting portion 26. Similarly to the case of the positive electrode 18, the negative electrode connecting portion 28 of the negative electrode 20 is provided with a through hole for inserting the second fastening member (rivet). The second conductive spacer is also provided with a through hole for inserting the second fastening member at a position overlapping the through hole of the negative electrode connecting portion 28. In each connection portion and each conductive spacer, two through holes are provided, but the number of through holes is not particularly limited.
　複数の正極１８の正極接続部２６は、電極群１２の積層方向に沿って重なるように配されるため、それらの貫通孔３６は一直線上に並んでいる。第１導電性スペーサ３０も、貫通孔３７が、対応する貫通孔３６と一直線上に並ぶように配置される。一直線上に並んだ貫通孔３６、３７に第１締結部材３４を挿通し、例えば、第１締結部材３４の端部（頭部）を潰して拡径することにより、複数の正極接続部２６が締結される。同様に、複数の負極接続部２８および第２導電性スペーサにおいても、貫通孔は一直線上に並んでおり、これらの貫通孔に挿通される第２締結部材により、複数の負極接続部２８が締結される。 Since the positive electrode connection portions 26 of the plurality of positive electrodes 18 are arranged so as to overlap in the stacking direction of the electrode group 12, the through holes 36 are aligned in a straight line. The first conductive spacers 30 are also arranged so that the through holes 37 are aligned with the corresponding through holes 36. By inserting the first fastening member 34 into the through holes 36 and 37 aligned in a straight line, for example, by crushing the end (head) of the first fastening member 34 and expanding the diameter, the plurality of positive electrode connection portions 26 are formed. It is concluded. Similarly, in the plurality of negative electrode connection portions 28 and the second conductive spacers, the through holes are aligned, and the plurality of negative electrode connection portions 28 are fastened by the second fastening member inserted through these through holes. Is done.
　第１締結部材３４は、正極集電体２２と同じ導電性材料で形成することが、高い耐食性が得られる点で好ましい。同様の理由で、第２締結部材も、第２集電体２４と同じ導電性材料で形成することが好ましい。 It is preferable that the first fastening member 34 is formed of the same conductive material as that of the positive electrode current collector 22 in terms of obtaining high corrosion resistance. For the same reason, the second fastening member is preferably formed of the same conductive material as that of the second current collector 24.
　正極１８と、正極外部端子４０とは、正極リード６２を介して電気的に接続されている。同様に、負極２０と、負極外部端子４２とは、負極リードを介して電気的に接続されている。図示例の正極リード６２は、横断面がＬ字形状の部材であり、互いに垂直な、板状の第１部分６２ａと、第２部分６２ｂとを有している。正極リード６２は、第１部分６２ａが封口板１６と平行で、かつ第２部分６２ｂが封口板１６と垂直になるように配置される。正極リード６２は、主として第２部分６２ｂが正極接続部２６と接触することで、正極１８と電気的に接続される。第２部分６２ｂは、第１締結部材３４を挿通するための１つ以上の貫通孔を有している。この貫通孔に挿通された第１締結部材３４により、第２部分６２ｂが正極接続部２６と接触した状態で固定され、これにより、正極リード６２が複数の正極１８の正極接続部２６に固定される。負極リードも、正極リード６２と同様の形状を有しており、正極リード６２の場合と同様にして、負極接続部２８に固体され、負極２０と電気的に接続される。 The positive electrode 18 and the positive external terminal 40 are electrically connected through a positive electrode lead 62. Similarly, the negative electrode 20 and the negative external terminal 42 are electrically connected via a negative electrode lead. The positive electrode lead 62 in the illustrated example is a member having an L-shaped cross section, and has a plate-like first portion 62a and a second portion 62b that are perpendicular to each other. The positive electrode lead 62 is disposed so that the first portion 62 a is parallel to the sealing plate 16 and the second portion 62 b is perpendicular to the sealing plate 16. The positive electrode lead 62 is electrically connected to the positive electrode 18 mainly when the second portion 62 b comes into contact with the positive electrode connecting portion 26. The second portion 62 b has one or more through holes for inserting the first fastening member 34. By the first fastening member 34 inserted through the through hole, the second portion 62b is fixed in contact with the positive electrode connection portion 26, whereby the positive electrode lead 62 is fixed to the positive electrode connection portions 26 of the plurality of positive electrodes 18. The The negative electrode lead also has the same shape as the positive electrode lead 62, and is solidified in the negative electrode connection portion 28 and electrically connected to the negative electrode 20 in the same manner as the positive electrode lead 62.
　キャパシタ１０を組み立てる際には、まず、正極１８と負極２０とをこれらの間にセパレータ２１を介在させた状態で積層することにより電極群１２を構成する。そして、構成された電極群１２をセルケースに収容する。その後、セルケースに非水電解質を注液し、電極群１２を構成するセパレータ２１、正極１８および負極２０の空隙に電解質を含浸する工程が行われる。なお、正極の水分量は、この非水電解質の注液工程の前に測定でき、セルケースに収容する前の電極群１２について測定してもよい。 When the capacitor 10 is assembled, first, the electrode group 12 is configured by laminating the positive electrode 18 and the negative electrode 20 with the separator 21 interposed therebetween. And the comprised electrode group 12 is accommodated in a cell case. Thereafter, a step of injecting a nonaqueous electrolyte into the cell case and impregnating the electrolyte into the gaps of the separator 21, the positive electrode 18, and the negative electrode 20 constituting the electrode group 12 is performed. The moisture content of the positive electrode can be measured before the nonaqueous electrolyte injection step, and may be measured for the electrode group 12 before being accommodated in the cell case.
　［付記］
　以上の実施形態に関し、さらに以下の付記を開示する。
　（付記１）
　正極集電体と、前記正極集電体に担持された正極合剤とを含むキャパシタ用正極であって、
　前記正極集電体は、アルミニウムまたはアルミニウム合金を含む三次元網目状の骨格を有し、
　前記正極合剤は、正極活物質およびバインダを少なくとも含み、
　前記正極活物質は、活性炭を含み、
　前記バインダは、結着性を有する高分子を含み、
　前記高分子の融点およびＪＩＳ　Ｋ７１９１に準拠した荷重たわみ温度の少なくとも一方が２５０℃以上であり、
　水分量は５００ｐｐｍ以下であるキャパシタ用正極。
　キャパシタにおいて、このような正極を用いると、正極集電体の表面に副生物が堆積することが抑制されるため、正極の抵抗が増加することを抑制できる。その結果、キャパシタのレート特性の低下を抑制できる。 [Appendix]
Regarding the above embodiment, the following additional notes are disclosed.
(Appendix 1)
A positive electrode for a capacitor comprising a positive electrode current collector and a positive electrode mixture supported on the positive electrode current collector,
The positive electrode current collector has a three-dimensional network skeleton containing aluminum or an aluminum alloy,
The positive electrode mixture includes at least a positive electrode active material and a binder,
The positive electrode active material includes activated carbon,
The binder includes a polymer having binding properties,
At least one of a melting point of the polymer and a deflection temperature under load in accordance with JIS K7191 is 250 ° C. or higher,
Capacitor positive electrode having a moisture content of 500 ppm or less.
When such a positive electrode is used in the capacitor, the accumulation of by-products on the surface of the positive electrode current collector is suppressed, so that an increase in the resistance of the positive electrode can be suppressed. As a result, it is possible to suppress a decrease in the rate characteristics of the capacitor.
　（付記２）
　厚みは５００μｍ～２０００μｍであり、
　電荷移動抵抗は１．５Ω・ｃｍ2以下であり、
　水分量は３００ｐｐｍ以下であり、
　前記高分子は、カルボキシメチルセルロース、カルボキシメチルセルロースのアルカリ金属塩、ポリイミド、およびポリアミドイミドからなる群より選択される少なくとも一種である付記１に記載のキャパシタ用正極。
　このような正極は、キャパシタのレート特性の低下を抑制する効果をさらに高めることができる。 (Appendix 2)
The thickness is 500 μm to 2000 μm,
The charge transfer resistance is 1.5 Ω · cm 2 or less,
The amount of water is 300 ppm or less,
The positive electrode for a capacitor according to appendix 1, wherein the polymer is at least one selected from the group consisting of carboxymethylcellulose, an alkali metal salt of carboxymethylcellulose, polyimide, and polyamideimide.
Such a positive electrode can further enhance the effect of suppressing a decrease in the rate characteristics of the capacitor.
　以下、本発明を実施例および比較例に基づいて具体的に説明するが、本発明は以下の実施例に限定されるものではない。 Hereinafter, the present invention will be specifically described based on examples and comparative examples, but the present invention is not limited to the following examples.
＜実施例１＞
　下記の手順でリチウムイオンキャパシタＡ１を作製した。
　（１）正極の作製
　（ａ）正極集電体の作製
　熱硬化性ポリウレタンの発泡体（気孔率：９５体積％、表面１インチ（＝２．５４ｃｍ）長さ当たりの空孔（セル）数：約５０個、縦１００ｍｍ×横３０ｍｍ×厚み１．１ｍｍ）を準備した。
　発泡体を、黒鉛、カーボンブラック（平均粒径Ｄ50：０．５μｍ）、樹脂バインダ、浸透剤、および消泡剤を含む導電性懸濁液の中に浸漬した後、乾燥することにより、発泡体の表面に導電性層を形成した。なお、懸濁液中の黒鉛およびカーボンブラックの含有量は合計で２５質量％であった。 <Example 1>
A lithium ion capacitor A1 was produced according to the following procedure.
(1) Production of positive electrode (a) Production of positive electrode current collector Thermosetting polyurethane foam (porosity: 95 vol%, surface 1 inch (= 2.54 cm) Number of pores (cells) per length: About 50, 100 mm long × 30 mm wide × 1.1 mm thick) were prepared.
The foam is immersed in a conductive suspension containing graphite, carbon black (average particle size D 50 : 0.5 μm), a resin binder, a penetrating agent, and an antifoaming agent, and then dried to foam. A conductive layer was formed on the surface of the body. The total content of graphite and carbon black in the suspension was 25% by mass.
　表面に導電性層を形成した発泡体を、溶融塩アルミニウムめっき浴中に浸漬して、電流密度３．６Ａ／ｄｍ2の直流電流を９０分間印加することにより、アルミニウム層を形成した。なお、発泡体の見掛け面積当たりのアルミニウム層の質量は、１５０ｇ／ｍ2であった。溶融塩アルミニウムめっき浴は、３３ｍｏｌ％の１－エチル－３－メチルイミダゾリウムクロライドおよび６７ｍｏｌ％の塩化アルミニウムを含み、温度は、４０℃であった。 The foam having a conductive layer formed on the surface was immersed in a molten salt aluminum plating bath, and a direct current having a current density of 3.6 A / dm 2 was applied for 90 minutes to form an aluminum layer. The mass of the aluminum layer per apparent area of the foam was 150 g / m 2 . The molten salt aluminum plating bath contained 33 mol% 1-ethyl-3-methylimidazolium chloride and 67 mol% aluminum chloride, and the temperature was 40 ° C.
　表面にアルミニウム層が形成された発泡体を、５００℃の塩化リチウム－塩化カリウム共晶溶融塩中に浸漬し、－１Ｖの負電位を３０分間印加することにより、発泡体を分解させた。得られたアルミニウム製の多孔体を、溶融塩から取り出して冷却し、水洗し、乾燥させることにより正極集電体を得た。得られた正極集電体は、発泡体の空孔形状を反映した、空孔が連通した三次元網目状の多孔構造を有し、気孔率は９４体積％であり、平均空孔径は５５０μｍであり、ＢＥＴ法による比表面積（ＢＥＴ比表面積）は、３５０ｃｍ2／ｇであり、厚みは１１００μｍであった。また、三次元網目状のアルミニウム製の骨格は、発泡体の除去により形成された連通孔状の空洞を内部に有していた。このようにして正極集電体を得た。 The foam with the aluminum layer formed on the surface was immersed in a lithium chloride-potassium chloride eutectic molten salt at 500 ° C., and a negative potential of −1 V was applied for 30 minutes to decompose the foam. The obtained aluminum porous body was taken out from the molten salt, cooled, washed with water, and dried to obtain a positive electrode current collector. The obtained positive electrode current collector has a three-dimensional network-like porous structure in which pores communicate, reflecting the pore shape of the foam, has a porosity of 94% by volume, and an average pore diameter of 550 μm. Yes, the BET specific surface area (BET specific surface area) was 350 cm 2 / g, and the thickness was 1100 μm. In addition, the three-dimensional mesh-like aluminum skeleton had a communication hole-like cavity formed by removing the foam. In this way, a positive electrode current collector was obtained.
　（ｂ）正極の作製
　正極活物質として活性炭粉末（比表面積２３００ｍ2／ｇ、平均粒径約５μｍ）および導電助剤としてアセチレンブラック、バインダとしてＣＭＣのＮａ塩、および分散媒としての水を、混合機にて混合、攪拌することにより、正極合剤スラリーを調製した。スラリー中の各成分の質量比は、活性炭：アセチレンブラック：ＣＭＣのＮａ塩＝９０：５：５であった。使用したＣＭＣのＮａ塩のエーテル化度は、０．９であり、１質量％濃度の水溶液の粘度は、２０ｍＰａ・ｓであった。なお、ＣＭＣのＮａ塩の融点は２９０℃であり、ＣＭＣのＮａ塩は荷重たわみ温度を有していない。また、バインダはＣＭＣのＮａ塩のみで構成している（バインダに占める高分子の量は１００質量％）。 (B) Preparation of positive electrode Activated carbon powder (specific surface area 2300 m 2 / g, average particle size of about 5 μm) as a positive electrode active material, acetylene black as a conductive additive, CMC Na salt as a binder, and water as a dispersion medium are mixed. A positive electrode mixture slurry was prepared by mixing and stirring in a machine. The mass ratio of each component in the slurry was activated carbon: acetylene black: NaC salt of CMC = 90: 5: 5. The degree of etherification of the Na salt of CMC used was 0.9, and the viscosity of an aqueous solution having a concentration of 1% by mass was 20 mPa · s. The melting point of the CMC Na salt is 290 ° C., and the CMC Na salt does not have a deflection temperature under load. Further, the binder is composed only of Na salt of CMC (the amount of polymer in the binder is 100% by mass).
　得られた正極合剤スラリーを、上記工程（ａ）で得られた集電体に充填し、充填物を、大気雰囲気中、１００℃で６０分間予備乾燥し、乾燥物を、乾燥雰囲気下（露点温度－６５℃）で、一対のロールを用いて厚み方向に圧縮した。得られた圧縮物を、２２０℃にて１２時間、減圧下（約０．１Ｐａ）で乾燥することにより、厚み８００μｍの正極を作製した。 The obtained positive electrode mixture slurry is filled in the current collector obtained in the above step (a), and the filling is pre-dried at 100 ° C. for 60 minutes in an air atmosphere. The film was compressed in the thickness direction using a pair of rolls at a dew point temperature of −65 ° C. The obtained compressed product was dried at 220 ° C. for 12 hours under reduced pressure (about 0.1 Pa) to produce a positive electrode having a thickness of 800 μm.
　（２）負極の作製
　（ａ）負極集電体の作製
　正極集電体の作製で用いたものと同じ熱硬化性ポリウレタンの発泡体の表面に、スパッタリングにより目付量５ｇ／ｃｍ2のＣｕ被膜（導電性層）を形成した。
　表面に導電性層を形成した発泡体をワークとして、硫酸銅めっき浴中に浸漬して、陰極電流密度２Ａ／ｄｍ2の直流電流を印加することにより、表面にＣｕ層を形成した。硫酸銅めっき浴は、２５０ｇ／Ｌの硫酸銅、５０ｇ／Ｌの硫酸、および３０ｇ／Ｌの塩化銅を含み、温度は、３０℃であった。 (2) Production of Negative Electrode (a) Production of Negative Electrode Current Collector A Cu film having a basis weight of 5 g / cm 2 is formed on the surface of the same thermosetting polyurethane foam as used in the production of the positive electrode current collector ( Conductive layer) was formed.
A foam having a conductive layer formed on the surface was used as a work, immersed in a copper sulfate plating bath, and a direct current having a cathode current density of 2 A / dm 2 was applied to form a Cu layer on the surface. The copper sulfate plating bath contained 250 g / L copper sulfate, 50 g / L sulfuric acid, and 30 g / L copper chloride, and the temperature was 30 ° C.
　表面にＣｕ層が形成された発泡体を、大気雰囲気下、７００℃で熱処理することにより、発泡体を分解させ、次いで、水素雰囲気下で焼成することにより表面に形成された酸化被膜を還元することにより、銅製の多孔体（負極集電体）を得た。得られた負極集電体は、発泡体の空孔形状を反映した、空孔が連通した三次元網目状の多孔構造を有し、気孔率は９２体積％であり、平均空孔径は５５０μｍであり、ＢＥＴ比表面積は２００ｃｍ2／ｇであった。また、三次元網目状の銅製の骨格は、発泡体の除去により形成された連通孔状の空洞を内部に有していた。 The foam with the Cu layer formed on the surface is heat-treated at 700 ° C. in an air atmosphere to decompose the foam, and then fired in a hydrogen atmosphere to reduce the oxide film formed on the surface. As a result, a copper porous body (negative electrode current collector) was obtained. The obtained negative electrode current collector has a three-dimensional network-like porous structure in which pores communicate, reflecting the pore shape of the foam, has a porosity of 92% by volume, and an average pore diameter of 550 μm. The BET specific surface area was 200 cm 2 / g. In addition, the three-dimensional network copper skeleton had a communication hole-like cavity formed by removing the foam.
　（ｂ）負極の作製
　負極活物質としての人造黒鉛粉末と、導電助剤としてのアセチレンブラックと、バインダとしてのＰＶＤＦと、分散媒としてのＮＭＰとを混合することにより、負極合剤スラリーを調製した。黒鉛粉末と、アセチレンブラックと、ＰＶＤＦとの質量比は、８７：８：５であった。 (B) Production of negative electrode A negative electrode mixture slurry was prepared by mixing artificial graphite powder as a negative electrode active material, acetylene black as a conductive additive, PVDF as a binder, and NMP as a dispersion medium. . The mass ratio of the graphite powder, acetylene black, and PVDF was 87: 8: 5.
　得られた負極合剤スラリーを、上記工程（ａ）で得られた集電体に充填し、充填物を大気雰囲気中、１００℃で６０分予備乾燥させた。乾燥物を、乾燥雰囲気下で、一対のロールを用いて厚み方向に圧縮した。圧縮物を、１２０℃にて１２時間、真空乾燥することにより、厚み２４０μｍの負極を作製した。得られた負極の水分量は、６０ｐｐｍであった。
　なお、工程（１）および（２）では、プレドープ後の負極の充電可能な容量が、正極の容量の約２倍となるように、正極合剤および負極合剤の充填量を調節した。 The obtained negative electrode mixture slurry was filled in the current collector obtained in the above step (a), and the filler was pre-dried at 100 ° C. for 60 minutes in the air atmosphere. The dried product was compressed in the thickness direction using a pair of rolls in a dry atmosphere. The compressed product was vacuum-dried at 120 ° C. for 12 hours to prepare a negative electrode having a thickness of 240 μm. The water content of the obtained negative electrode was 60 ppm.
In steps (1) and (2), the filling amounts of the positive electrode mixture and the negative electrode mixture were adjusted so that the chargeable capacity of the negative electrode after pre-doping was about twice the capacity of the positive electrode.
　（３）リチウム極の作製
　集電体としてのパンチング銅箔（厚み：２０μｍ、開口径：５０μｍ、開口率５０％、２ｃｍ×２ｃｍ）の一方の表面に、リチウム箔（厚み：５０μｍ）を圧着することにより、リチウム極を作製した。リチウム極の集電体の他方の表面には、ニッケル製のリードを溶接した。リチウム極の作製は、乾燥雰囲気下（温度２５℃、露点－５０℃以下）で行った。 (3) Production of lithium electrode A lithium foil (thickness: 50 μm) is pressure-bonded to one surface of a punching copper foil (thickness: 20 μm, opening diameter: 50 μm, opening ratio 50%, 2 cm × 2 cm) as a current collector. Thus, a lithium electrode was produced. A nickel lead was welded to the other surface of the current collector of the lithium electrode. The lithium electrode was produced in a dry atmosphere (temperature 25 ° C., dew point −50 ° C. or lower).
　（４）リチウムイオンキャパシタの作製
　上記（１）で得られた正極を所定サイズに切り出し、端部には、１ｃｍ×４ｃｍのサイズの正極集電体露出部（タブ）を形成した。上記（２）で得られた負極を所定サイズに切り出し、端部には、１ｃｍ×４ｃｍのサイズの負極集電体露出部（タブ）を形成した。正極のサイズは、タブを除いて８．５ｃｍ×１０ｃｍであり、負極のサイズは、タブを除いて、８．５ｃｍ×１０．５ｃｍとした。正極集電体露出部には、アルミニウム製のリードを、負極集電体露出部には、ニッケル製のリードを、それぞれ溶接した。 (4) Production of Lithium Ion Capacitor The positive electrode obtained in (1) was cut into a predetermined size, and a positive electrode current collector exposed portion (tab) having a size of 1 cm × 4 cm was formed at the end. The negative electrode obtained in (2) above was cut into a predetermined size, and a negative electrode current collector exposed portion (tab) having a size of 1 cm × 4 cm was formed at the end. The size of the positive electrode was 8.5 cm × 10 cm excluding the tab, and the size of the negative electrode was 8.5 cm × 10.5 cm excluding the tab. The lead made of aluminum was welded to the exposed portion of the positive electrode current collector, and the lead made of nickel was welded to the exposed portion of the negative electrode current collector.
　正極と負極との間に、乾燥させたセルロース製のセパレータ（厚み：６０μｍ）を介在させて正極と負極とを積層することにより単セルの電極群を形成した。電極群の形成は、露点温度－６５℃程度の雰囲気下で行った。さらに、電極群の負極側に、上記と同様のセパレータを介在させて、リチウム極を配置し、得られた積層物を、アルミニウムラミネートシートで作製されたセルケース内に収容した。セパレータの水分量をカールフィッシャー法により測定したところ、電極群を形成する前の段階で、２００ｐｐｍであった。 A single cell electrode group was formed by laminating the positive electrode and the negative electrode with a dried cellulose separator (thickness: 60 μm) interposed between the positive electrode and the negative electrode. The electrode group was formed in an atmosphere having a dew point temperature of about −65 ° C. Further, a lithium electrode was arranged on the negative electrode side of the electrode group with the same separator as above, and the obtained laminate was accommodated in a cell case made of an aluminum laminate sheet. When the moisture content of the separator was measured by the Karl Fischer method, it was 200 ppm at the stage before the electrode group was formed.
　次いで、非水電解質をセルケース内に注入して、正極、負極およびセパレータに含浸させた。非水電解質としては、エチレンカーボネートおよびジエチルカーボネートを体積比１：１で含む混合溶媒に、リチウム塩としてＬｉＰＦ6を１．０ｍｏｌ／Ｌの濃度となるように溶解させた溶液を用いた。用いた非水電解質中の水分量は、５０ｐｐｍであった。最後に真空シーラーにて減圧しながらセルケースを封止した。 Next, a nonaqueous electrolyte was injected into the cell case, and impregnated into the positive electrode, the negative electrode, and the separator. As the non-aqueous electrolyte, a solution in which LiPF 6 as a lithium salt was dissolved to a concentration of 1.0 mol / L in a mixed solvent containing ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1 was used. The amount of water in the nonaqueous electrolyte used was 50 ppm. Finally, the cell case was sealed while reducing the pressure with a vacuum sealer.
　負極のリード線とリチウム極のリード線とを、セルケース外部で電源に接続した。この状態のセルを、３０℃の恒温槽内で、電解質の温度が恒温槽の温度と同じになるように所定時間静置した。次いで、負極とリチウム極との間で、０．２ｍＡ／ｃｍ2の電流で、金属リチウムに対して０Ｖの電位まで充電した後、０．２ｍＡ／ｃｍ2の電流で２．３ｍＡｈ放電して、負極活物質にリチウムをプレドープした。プレドープ後、セルを３０℃で１２時間加熱することによりエージングした。 The negative electrode lead wire and the lithium electrode lead wire were connected to a power source outside the cell case. The cell in this state was allowed to stand for a predetermined time in a thermostat at 30 ° C. so that the temperature of the electrolyte was the same as the temperature of the thermostat. Then, between the negative electrode and the lithium electrode, with a current 0.2 mA / cm 2, it was charged to a potential of 0V with respect to metallic lithium, and 2.3mAh discharged at a current 0.2 mA / cm 2, The negative electrode active material was predoped with lithium. After pre-doping, the cell was aged by heating at 30 ° C. for 12 hours.
　エージングしたセルを、０．５ｍＡ／ｃｍ2の電流で、上限電圧３．８Ｖまで充電し、０．５ｍＡ／ｃｍ2の電流で、電圧が２．２Ｖになるまで放電する充放電サイクルを１０回繰り返すことにより慣らし充放電を行った。そして、セル内で発生したガスを、ラミネートを一度開封することにより、セル外に排出した。このようにして、リチウムイオンキャパシタ（Ａ１）を作製した。リチウムイオンキャパシタＡ１の設計容量は、３．８Ｖ充電時で約１．０ｍＡｈ／ｃｍ2であった。 10 charge / discharge cycles in which the aged cell is charged at a current of 0.5 mA / cm 2 to an upper limit voltage of 3.8 V and discharged at a current of 0.5 mA / cm 2 until the voltage reaches 2.2 V. The running-in and charging were performed by repeating. The gas generated in the cell was discharged out of the cell by opening the laminate once. In this way, a lithium ion capacitor (A1) was produced. The design capacity of the lithium ion capacitor A1 was about 1.0 mAh / cm 2 when charged at 3.8V.
　リチウムイオンキャパシタを用いて、下記の評価を行った。
　（ａ）正極の水分量
　非水電解質の注液前の段階で、電極群を分解し、正極を取り出して、カールフィッシャー法により正極の水分量を測定した。具体的には、まず、取り出した正極を、幅２ｃｍ×長さ１０ｃｍのサイズに切り出し、試験片を作製した。試験片をドライルーム（温度２５℃，露点－５０℃以下）で１時間放置した。その後、ドライルーム内に設置した電量滴定式水分計を用い、水分気化法（気化温度１５０℃）により水分量を測定した。測定値に基づいて、正極に含まれる水分量を算出した。 The following evaluation was performed using a lithium ion capacitor.
(A) Moisture content of positive electrode In the stage before pouring the nonaqueous electrolyte, the electrode group was disassembled, the positive electrode was taken out, and the moisture content of the positive electrode was measured by the Karl Fischer method. Specifically, first, the taken out positive electrode was cut into a size of 2 cm wide × 10 cm long to prepare a test piece. The test piece was left in a dry room (temperature 25 ° C., dew point −50 ° C. or less) for 1 hour. Thereafter, the moisture content was measured by a moisture vaporization method (vaporization temperature 150 ° C.) using a coulometric titration moisture meter installed in a dry room. Based on the measured value, the amount of water contained in the positive electrode was calculated.
　（ｂ）セル抵抗
　５ｍＡ／ｃｍ2の電流で、上限電圧３．８Ｖまで充電し、５ｍＡ／ｃｍ2の電流で、電圧が２．２Ｖになるまで放電する充放電サイクルを５回繰り返した。各サイクルについて、充電終止電圧と放電初期電圧との差（ΔＶ）を、放電電流で除した値を求め、これらの平均値をセル抵抗とした。 In the current (b) the cell resistance 5 mA / cm 2, and charged to the upper limit voltage 3.8 V, at 5 mA / cm 2 current was repeated charge-discharge cycle for discharging until the voltage becomes 2.2V 5 times. For each cycle, a value obtained by dividing the difference (ΔV) between the end-of-charge voltage and the initial discharge voltage by the discharge current was determined, and the average value was taken as the cell resistance.
　（ｃ）正極の電荷移動抵抗
　正極の電荷移動抵抗を、交流インピーダンス法により、電圧振幅５ｍＶおよび周波数範囲０．０１Ｈｚ～１０ｋＨｚの条件で測定した。具体的には、交流インピーダンス測定で得られるナイキスト線図に基づいて、電荷移動抵抗を求めた。 (C) Charge transfer resistance of positive electrode The charge transfer resistance of the positive electrode was measured by the AC impedance method under the conditions of a voltage amplitude of 5 mV and a frequency range of 0.01 Hz to 10 kHz. Specifically, the charge transfer resistance was determined based on the Nyquist diagram obtained by AC impedance measurement.
　（ｄ）レート特性
　２Ｃの電流で、３．８Ｖまで充電し、２Ｃまたは５０Ｃの電流で、電圧が２．２Ｖになるまで放電した。このときの放電容量（ｍＡｈ）を求めた。２Ｃの電流で放電したときの放電容量を「放電容量Ａ」とし、５０Ｃの電流で放電したときの放電容量を「放電容量Ｂ」とした。
　放電容量Ａに対する放電容量Ｂの比率（百分率）を指標として、リチウムイオンキャパシタのレート特性を評価した。 (D) Rate characteristics The battery was charged to 3.8V with a current of 2C and discharged until the voltage became 2.2V with a current of 2C or 50C. The discharge capacity (mAh) at this time was determined. The discharge capacity when discharged at a current of 2 C was “discharge capacity A”, and the discharge capacity when discharged at a current of 50 C was “discharge capacity B”.
Using the ratio (percentage) of the discharge capacity B to the discharge capacity A as an index, the rate characteristics of the lithium ion capacitor were evaluated.
＜実施例２、３＞
　正極の水分量が表１の値となるように、実施例１の（１）（ｂ）において、圧縮物を乾燥する際の時間を調整した以外は、実施例１と同様に正極を作製した。得られた正極を用いる以外は、実施例１と同様にリチウムイオンキャパシタＡ２およびＡ３を作製し、評価を行った。 <Examples 2 and 3>
A positive electrode was produced in the same manner as in Example 1 except that the time for drying the compressed material was adjusted in (1) and (b) of Example 1 so that the moisture content of the positive electrode was the value shown in Table 1. . Except for using the obtained positive electrode, lithium ion capacitors A2 and A3 were prepared and evaluated in the same manner as in Example 1.
＜比較例１～３＞
　正極の水分量が表１の値となるように、実施例１の（１）（ｂ）において、圧縮物を乾燥する際の時間を調整した以外は、実施例１と同様に正極を作製した。得られた正極を用いる以外は、実施例１と同様にリチウムイオンキャパシタＢ１～Ｂ３を作製し、評価を行った。 <Comparative Examples 1 to 3>
A positive electrode was produced in the same manner as in Example 1 except that the time for drying the compressed material was adjusted in (1) and (b) of Example 1 so that the moisture content of the positive electrode was the value shown in Table 1. . Except for using the obtained positive electrode, lithium ion capacitors B1 to B3 were prepared and evaluated in the same manner as in Example 1.
＜比較例４＞
　実施例１の（１）（ｂ）において、ＣＭＣのＮａ塩に代えて、ＰＶＤＦをバインダとして用い、圧縮物を乾燥する際の温度を１２０℃に変更した以外は、実施例１と同様に正極を作製した。得られた正極を用いる以外は、実施例１と同様にリチウムイオンキャパシタＢ４を作製し、評価を行った。 <Comparative example 4>
In Example 1 (1) and (b), in place of CMC Na salt, PVDF was used as a binder, and the temperature at which the compressed product was dried was changed to 120 ° C. As in Example 1, the positive electrode Was made. A lithium ion capacitor B4 was produced and evaluated in the same manner as in Example 1 except that the obtained positive electrode was used.
　実施例（リチウムイオンキャパシタＡ１～Ａ３）および比較例（リチウムイオンキャパシタＢ１～Ｂ４）の評価結果を表１に示す。 Table 1 shows the evaluation results of the examples (lithium ion capacitors A1 to A3) and the comparative examples (lithium ion capacitors B1 to B4).
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１に示されるように、水分量が５００ｐｐｍより多い正極を用いた比較例のキャパシタＢ１～Ｂ４では、正極の抵抗（正極の電荷移動抵抗）およびセル抵抗が高く、レート特性が低くなった。
　それに対して、水分量が５００ｐｐｍ以下の正極を用いた実施例のキャパシタＡ１～Ａ３では、正極の抵抗（正極の電荷移動抵抗）が低くなった。これに伴い、セル抵抗が顕著に低下し、レート特性が大きく向上した。これは、水分量が低減された正極を用いたことで、副反応が抑制され、正極集電体の表面への副生物の堆積が低減されたためと考えられる。キャパシタＡ３では、正極の抵抗（正極の電荷移動抵抗）が特に小さく、レート特性は特に優れたものとなっている。 As shown in Table 1, in the capacitors B1 to B4 of the comparative examples using the positive electrode having a water content of more than 500 ppm, the positive electrode resistance (positive electrode charge transfer resistance) and cell resistance were high, and the rate characteristics were low.
In contrast, in the capacitors A1 to A3 of the example using the positive electrode having a moisture content of 500 ppm or less, the resistance of the positive electrode (charge transfer resistance of the positive electrode) was low. Along with this, the cell resistance was remarkably reduced, and the rate characteristics were greatly improved. This is presumably because the use of the positive electrode with a reduced amount of moisture suppressed side reactions and reduced the accumulation of by-products on the surface of the positive electrode current collector. In the capacitor A3, the positive electrode resistance (positive electrode charge transfer resistance) is particularly small, and the rate characteristics are particularly excellent.
　また、ＰＶＤＦをバインダとして含む正極を用いたＢ４では、正極の乾燥温度をＰＶＤＦの融点以上に上げることができず、十分な乾燥を行うことができなかった。そのため、正極の水分量が多く、副生物が正極集電体の表面に堆積したことにより、正極の抵抗が増加したものと考えられる。なお、ＰＶＤＦの融点は１７０℃であり、ＰＶＤＦの荷重たわみ温度は１５６℃である。 Moreover, in B4 using a positive electrode containing PVDF as a binder, the drying temperature of the positive electrode could not be raised to the melting point of PVDF or more, and sufficient drying could not be performed. Therefore, it is considered that the resistance of the positive electrode is increased because the amount of water in the positive electrode is large and by-products are deposited on the surface of the positive electrode current collector. The melting point of PVDF is 170 ° C., and the deflection temperature under load of PVDF is 156 ° C.
　本発明の一実施形態に係るキャパシタ用正極およびキャパシタでは、正極の抵抗の増加が抑制されており、優れたレート特性が得られる。そのため、高レートが求められる様々な用途に適用することができる。 In the positive electrode for a capacitor and the capacitor according to one embodiment of the present invention, an increase in the resistance of the positive electrode is suppressed, and an excellent rate characteristic is obtained. Therefore, it can be applied to various uses that require a high rate.
　１０：キャパシタ、１２：電極群、１４：ケース本体、１６：封口板
　１８：正極、２０：負極、２１：セパレータ
　２２：正極集電体、２４：負極集電体
　２６：正極接続部、２８：負極接続部
　３０：第１導電性スペーサ、３４：第１締結部材、３６、３７：貫通孔
　４０：正極外部端子、４２：負極外部端子、４４：安全弁、４８：液栓
　６２：正極リード、６２ａ：第１部分、６２ｂ：第２部分 10: capacitor, 12: electrode group, 14: case body, 16: sealing plate 18: positive electrode, 20: negative electrode, 21: separator 22: positive electrode current collector, 24: negative electrode current collector 26: positive electrode connection part, 28: Negative electrode connection portion 30: first conductive spacer, 34: first fastening member, 36, 37: through hole 40: positive electrode external terminal, 42: negative electrode external terminal, 44: safety valve, 48: liquid stopper 62: positive electrode lead, 62a : First part, 62b: Second part

Claims (10)

  1. 　正極集電体と、前記正極集電体に担持された正極合剤とを含むキャパシタ用正極であって、
    　前記正極集電体は、アルミニウムまたはアルミニウム合金を含む三次元網目状の骨格を有し、
    　前記正極合剤は、正極活物質およびバインダを少なくとも含み、
    　前記正極活物質は、活性炭を含み、
    　前記バインダは、融点およびＪＩＳ　Ｋ７１９１に準拠した荷重たわみ温度の少なくとも一方が２５０℃以上である高分子を含み、
    　水分量は５００ｐｐｍ以下であるキャパシタ用正極。     A positive electrode for a capacitor comprising a positive electrode current collector and a positive electrode mixture supported on the positive electrode current collector,
    The positive electrode current collector has a three-dimensional network skeleton containing aluminum or an aluminum alloy,
    The positive electrode mixture includes at least a positive electrode active material and a binder,
    The positive electrode active material includes activated carbon,
    The binder includes a polymer in which at least one of a melting point and a deflection temperature under load according to JIS K7191 is 250 ° C. or higher.
    Capacitor positive electrode having a moisture content of 500 ppm or less.
  2. 　電荷移動抵抗は２Ω・ｃｍ2以下である請求項１に記載のキャパシタ用正極。 The positive electrode for a capacitor according to claim 1, wherein the charge transfer resistance is 2 Ω · cm 2 or less.
  3. 　前記高分子は、カルボキシアルキルセルロース、カルボキシアルキルセルロース塩、およびポリイミド樹脂からなる群より選択される少なくとも一種である請求項１または請求項２に記載のキャパシタ用正極。 3. The positive electrode for a capacitor according to claim 1, wherein the polymer is at least one selected from the group consisting of carboxyalkyl cellulose, carboxyalkyl cellulose salt, and polyimide resin.
  4. 　前記高分子は、カルボキシメチルセルロース、カルボキシメチルセルロースのアルカリ金属塩、ポリイミド、およびポリアミドイミドからなる群より選択される少なくとも一種である請求項１～請求項３のいずれか１項に記載のキャパシタ用正極。 The positive electrode for a capacitor according to any one of claims 1 to 3, wherein the polymer is at least one selected from the group consisting of carboxymethylcellulose, an alkali metal salt of carboxymethylcellulose, polyimide, and polyamideimide.
  5. 　水分量は３００ｐｐｍ以下である請求項１～請求項４のいずれか１項に記載のキャパシタ用正極。 The capacitor positive electrode according to any one of claims 1 to 4, wherein the moisture content is 300 ppm or less.
  6. 　５００μｍ～２０００μｍの厚みを有する請求項１～請求項５のいずれか１項に記載のキャパシタ用正極。 6. The positive electrode for a capacitor according to claim 1, wherein the positive electrode for a capacitor has a thickness of 500 μm to 2000 μm.
  7. 　前記バインダに占める前記高分子の量は、９０質量％～１００質量％であり、
    　前記バインダの量は、前記正極活物質１００質量部に対して、１０質量部以下である請求項１～請求項６のいずれか１項に記載のキャパシタ用正極。     The amount of the polymer in the binder is 90% by mass to 100% by mass,
    The positive electrode for a capacitor according to any one of claims 1 to 6, wherein an amount of the binder is 10 parts by mass or less with respect to 100 parts by mass of the positive electrode active material.
  8. 　正極を準備する工程（ａ）、
    　前記正極と、負極と、正極および負極の間に介在するセパレータとで電極群を形成する工程（ｂ）、ならびに
    　前記電極群および非水電解質をセルケース内に収容する工程（ｃ）を含み、
    　前記工程（ａ）は、
    　活性炭を含む正極活物質と、融点およびＪＩＳ　Ｋ７１９１に準拠した荷重たわみ温度の少なくとも一方が２５０℃以上である高分子を含むバインダとを、少なくとも含む正極合剤を調製する工程（ａ１）、
    　前記正極合剤を、アルミニウムまたはアルミニウム合金を含む三次元網目状の骨格を有する正極集電体に充填する工程（ａ２）、
    　前記工程（ａ２）で得られた充填物を厚み方向に圧縮する工程（ａ３）、ならびに
    　前記工程（ａ３）で得られた圧縮物を、前記電極群が前記非水電解質と接触する前の状態において、前記正極の水分量が５００ｐｐｍ以下となるように、２００℃以上で、かつ前記高分子の前記融点および前記荷重たわみ温度の低い方よりも低い温度で乾燥する工程（ａ４）、を含む、キャパシタの製造方法。     Preparing a positive electrode (a),
    A step (b) of forming an electrode group with the positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and a step (c) of accommodating the electrode group and a non-aqueous electrolyte in a cell case,
    The step (a)
    A step (a1) of preparing a positive electrode mixture containing at least a positive electrode active material containing activated carbon, and a binder containing at least one of a melting point and a deflection temperature under load in accordance with JIS K7191 of 250 ° C. or higher;
    Filling the positive electrode mixture into a positive electrode current collector having a three-dimensional network skeleton containing aluminum or an aluminum alloy (a2),
    The step (a3) of compressing the packing obtained in the step (a2) in the thickness direction, and the compressed product obtained in the step (a3) before the electrode group comes into contact with the nonaqueous electrolyte. And (a4) drying at a temperature lower than the melting point of the polymer and the lower deflection temperature under load so that the water content of the positive electrode is 500 ppm or less. A method for manufacturing a capacitor.
  9. 　前記工程（ａ４）において、前記圧縮物を、減圧下、遠赤外線下、または減圧下および遠赤外線下で乾燥する、請求項８に記載のキャパシタの製造方法。 The method for producing a capacitor according to claim 8, wherein in the step (a4), the compressed product is dried under reduced pressure, far infrared rays, or reduced pressure and far infrared rays.
  10. 　前記非水電解質は、アルカリ金属イオン伝導性を有し、
    　前記負極は、負極集電体と、前記負極集電体に担持され、かつ負極活物質を含む負極合剤とを含み、
    　前記負極集電体は、三次元網目状の金属の骨格を有し、
    　前記負極活物質は、アルカリ金属イオンを可逆的に担持する材料を含む請求項８または請求項９に記載のキャパシタの製造方法。     The non-aqueous electrolyte has alkali metal ion conductivity,
    The negative electrode includes a negative electrode current collector and a negative electrode mixture supported on the negative electrode current collector and including a negative electrode active material,
    The negative electrode current collector has a three-dimensional network metal skeleton,
    The method for manufacturing a capacitor according to claim 8, wherein the negative electrode active material includes a material that reversibly carries alkali metal ions.
PCT/JP2015/067889 2014-07-01 2015-06-22 Cathode for capacitor and method for producing capacitor WO2016002564A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2014-135781 2014-07-01
JP2014135781A JP2017152416A (en) 2014-07-01 2014-07-01 Capacitor positive electrode and method of manufacturing capacitor

Publications (1)

Publication Number Publication Date
WO2016002564A1 true WO2016002564A1 (en) 2016-01-07

Family

ID=55019108

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2015/067889 WO2016002564A1 (en) 2014-07-01 2015-06-22 Cathode for capacitor and method for producing capacitor

Country Status (2)

Country Link
JP (1) JP2017152416A (en)
WO (1) WO2016002564A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7093505B2 (en) * 2018-08-08 2022-06-30 トヨタ自動車株式会社 A positive electrode for a lithium ion capacitor, a lithium ion capacitor using the positive electrode, and a method for manufacturing them.

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010109355A (en) * 2008-09-30 2010-05-13 Nippon Chemicon Corp Electrical double-layer capacitor
WO2012117910A1 (en) * 2011-03-01 2012-09-07 Jsr株式会社 Slurry for storage device electrode, storage device electrode, and storage device
JP2012186141A (en) * 2011-02-18 2012-09-27 Sumitomo Electric Ind Ltd Electrochemical device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010109355A (en) * 2008-09-30 2010-05-13 Nippon Chemicon Corp Electrical double-layer capacitor
JP2012186141A (en) * 2011-02-18 2012-09-27 Sumitomo Electric Ind Ltd Electrochemical device
WO2012117910A1 (en) * 2011-03-01 2012-09-07 Jsr株式会社 Slurry for storage device electrode, storage device electrode, and storage device

Also Published As

Publication number Publication date
JP2017152416A (en) 2017-08-31

Similar Documents

Publication Publication Date Title
WO2015098903A1 (en) Alkali metal ion capacitor
EP3109876A1 (en) Storage device and charging/discharging device
JP2015011823A (en) Lithium battery
WO2014148250A1 (en) Lithium ion capacitor and method for charging and discharging same
WO2015105136A1 (en) Positive electrode for lithium ion capacitors and lithium ion capacitor using same
JP6260209B2 (en) Alkali metal ion capacitor, method for producing the same and charge / discharge method
JP6217434B2 (en) Sodium molten salt battery
KR20140138739A (en) Electrode material, and capacitor and secondary battery using said electrode material
WO2016002564A1 (en) Cathode for capacitor and method for producing capacitor
JP2013143422A (en) Lithium ion capacitor
EP3109877A1 (en) Capacitor and method for charging and discharging same
WO2015093289A1 (en) Lithium ion capacitor
WO2015107800A1 (en) Copper porous body, electrode for electricity storage devices, and electricity storage device
JP2016171239A (en) Manufacturing method of lithium ion capacitor, and lithium ion capacitor
US20090027830A1 (en) Non-Aqueous Capacitor and Method for Manufacturing the Same
WO2015107965A1 (en) Aluminum porous body, electrode for electricity storage devices, and electricity storage device
JP2015204437A (en) lithium ion capacitor
WO2015087591A1 (en) Capacitor and method for charging/discharging same
JP2016181603A (en) Lithium ion capacitor
JP2015133183A (en) sodium molten salt battery
JP2017098365A (en) Lithium ion capacitor, and electronic device with lithium ion capacitor attached thereto
JP2007019491A (en) Electric double layer capacitor and electrode therefor
JP2017098363A (en) Lithium ion capacitor, and electronic device with lithium ion capacitor attached thereto
JP2013115179A (en) Lithium ion capacitor

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 15814067

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

NENP Non-entry into the national phase

Ref country code: JP

122 Ep: pct application non-entry in european phase

Ref document number: 15814067

Country of ref document: EP

Kind code of ref document: A1