WO2020111084A1 - Electrode for redox flow battery, method for manufacturing same, redox flow battery, and conductive sheet material for electrode - Google Patents

Electrode for redox flow battery, method for manufacturing same, redox flow battery, and conductive sheet material for electrode Download PDF

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Publication number
WO2020111084A1
WO2020111084A1 PCT/JP2019/046255 JP2019046255W WO2020111084A1 WO 2020111084 A1 WO2020111084 A1 WO 2020111084A1 JP 2019046255 W JP2019046255 W JP 2019046255W WO 2020111084 A1 WO2020111084 A1 WO 2020111084A1
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electrode
layer
nanocarbon
redox flow
flow battery
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PCT/JP2019/046255
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French (fr)
Japanese (ja)
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丈智 西方
みゆき 冨田
ティンティン シュウ
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昭和電工株式会社
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Publication of WO2020111084A1 publication Critical patent/WO2020111084A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/96—Carbon-based electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/18—Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to an electrode for a redox flow battery in which an electrolyte is circulated for charging and discharging, a manufacturing method thereof, and a redox flow battery having the electrode and a conductive sheet material for the electrode.
  • redox flow batteries which are electrolyte flow batteries.
  • a redox flow battery supplies and circulates a positive electrode electrolytic solution and a negative electrode electrolytic solution to and from a battery cell having a positive electrode, a negative electrode, and a diaphragm interposed between both electrodes, and a power converter (for example, an AC/DC converter or the like).
  • a power converter for example, an AC/DC converter or the like.
  • an aqueous solution containing a metal ion (active material) whose valence changes by redox is usually used.
  • a redox flow battery for example, a vanadium redox flow battery using vanadium (V) as an active material of a positive electrode and a negative electrode is well known.
  • Carbon materials such as carbon nanotubes and carbon fibers are used as the material of the electrodes used in such a redox flow battery.
  • the present applicant discloses in Patent Document 1 that as an electrode material for a redox flow battery, a conductive sheet containing carbon nanotubes having an average fiber diameter of 1 ⁇ m or less and carbon fibers having an average fiber diameter of more than 1 ⁇ m, and an average fiber.
  • porous sheets made of carbon fibers having a diameter larger than 1 ⁇ m are laminated.
  • the redox flow battery described in Patent Document 1 has a large electric capacity, a low cell resistivity, and a small pressure loss when an electrolytic solution is passed through the electrodes. It cannot be said that the performance such as the rate is sufficient, and there is room for further improvement.
  • a laminated structure of an electrode of a redox flow battery when a laminated structure of an electrode of a redox flow battery is produced, a laminated structure is constituted by two layers of a conductive sheet containing carbon nanotubes and carbon fibers and a porous sheet made of carbon fibers. , The electrodes were made.
  • the conductive sheet tends to have low mechanical strength because it contains fine carbon nanotubes, and as a result, the mechanical strength as an electrode also tends to be low. Therefore, for a redox flow battery having sufficiently high mechanical strength. An electrode was sought.
  • An object of the present invention is to contribute to reduction of cell resistivity of a redox flow battery, and an electrode for a redox flow battery having sufficiently high mechanical strength, a method for producing the same, and a redox flow battery and a conductive sheet for an electrode. To provide the material.
  • the present inventors have arranged a first porous layer composed of carbon fibers on one surface of a composite conductive layer composed of both a nanocarbon material and carbon fibers for an electrode for a redox flow battery,
  • An integrated redox flow battery electrode with a nanocarbon layer composed of a nanocarbon material on the other side makes the mechanical strength of the electrode higher and damages less likely to occur, as well as redox flow.
  • the inventors have found that the cell resistivity is low when used in batteries, and have completed the present invention. More specifically, the present invention provides the following.
  • the present invention provides a composite conductive layer composed of both a nanocarbon material and a carbon fiber having an average fiber diameter of 1 ⁇ m or more, and one of the both surfaces of the composite conductive layer.
  • An electrode for a redox flow battery comprising: a first porous layer composed of and a nanocarbon layer located on the other surface of the composite conductive layer and composed of the nanocarbon material.
  • each of the nanocarbon layer and the composite conductive layer has a thickness of 0.01 mm to 0.20 mm, and the first porous layer has a thickness of 0.05 mm.
  • the electrode for a redox flow battery according to (1) which has a thickness of up to 0.30 mm.
  • the present invention further comprises a second porous layer which is located on a surface opposite to the composite conductive layer on both surfaces of the nanocarbon layer and which is composed of the carbon fiber.
  • a second porous layer which is located on a surface opposite to the composite conductive layer on both surfaces of the nanocarbon layer and which is composed of the carbon fiber.
  • it is the electrode for a redox flow battery according to (2).
  • the present invention is the electrode for a redox flow battery according to (3), wherein the thickness dimension of the second porous layer is 0.10 mm to 0.50 mm.
  • the present invention also provides the electrode for redox flow battery according to (3) or (4), wherein the thickness dimension of the first porous layer is smaller than the thickness dimension of the second porous layer. Is.
  • the present invention is the electrode for a redox flow battery according to any one of (1) to (5), wherein the nanocarbon material contains carbon nanotubes having an average fiber diameter of less than 1 ⁇ m.
  • the composite conductive layer contains 20 parts by mass to 90 parts by mass of the carbon fiber with respect to 100 parts by mass in total of the nanocarbon material and the carbon fiber, (1) to (6) ) It is an electrode for redox flow batteries as described in any one of the above.
  • the present invention is a redox flow battery having the electrode for redox flow battery according to any one of (1) to (7).
  • the present invention provides the redox flow battery electrode according to any one of (1) to (7) between the ion exchange membrane and the electrode plate, wherein the first porous layer is It is a redox flow battery provided so as to face an ion exchange membrane.
  • the present invention is a composite conductive layer composed of both a nanocarbon material and a carbon fiber having an average fiber diameter of 1 ⁇ m or more;
  • a conductive sheet material for an electrode comprising a first porous layer composed of carbon fibers and a nanocarbon layer located on the other surface of the composite conductive layer and composed of the nanocarbon material.
  • the present invention further comprises a second porous layer which is located on a surface opposite to the composite conductive layer on both surfaces of the nanocarbon layer and which is composed of the carbon fiber.
  • the present invention is a method for producing an electrode for a redox flow battery, wherein a composite dispersion liquid containing a nanocarbon material and carbon fibers is applied to one surface of the first porous layer and dried to form a composite. And a step of forming a conductive layer, and applying a nanocarbon dispersion liquid containing the nanocarbon material to a surface of the composite conductive layer opposite to the first porous layer on both surfaces of the composite conductive layer, followed by drying to form a nanoparticle. And a step of forming a carbon layer, which is a method for manufacturing an electrode for a redox flow battery.
  • an electrode for a redox flow battery which can contribute to reduction of the cell resistivity of the redox flow battery and has sufficiently high mechanical strength, and a manufacturing method thereof.
  • FIG. 1 is a cross-sectional view showing an example of a redox flow battery electrode (hereinafter, may be simply referred to as “electrode”) according to the present embodiment.
  • the redox flow battery electrode 1 according to the present embodiment includes a composite conductive layer 11, a first porous layer 12 located on one surface of both surfaces of the composite conductive layer 11, and the other surface of the composite conductive layer 11. And the nanocarbon layer 13 located in the main structure. Further, it is preferable that the electrode 1 further has a second porous layer 15 located on the surface opposite to the composite conductive layer 11 on both surfaces of the nanocarbon layer 13.
  • the nanocarbon layer 13, the composite conductive layer 11, and the first porous layer 12 are sequentially provided on one surface of the second porous layer 15.
  • the first porous layer 12 is laminated so as to face the ion exchange membrane 60 described later.
  • the second porous layer 15 is provided such that the other surface thereof is adjacent to or opposite to the electrode plate 16 described later.
  • the redox flow battery electrode 1 has a laminated structure including at least three layers of the composite conductive layer 11, the first porous layer 12, and the nanocarbon layer 13, so that the mechanical structure of the electrode 1 is improved. Since the strength is increased, the overall thickness of the electrode 1 can be reduced, and the cell resistivity of the redox flow battery can be reduced accordingly.
  • the composite conductive layer 11 and the nanocarbon layer 13 containing the fine nanocarbon material are provided in the first porous layer 12 when the electrode laminated structure is produced. Since the layers can be laminated by a method such as sequentially coating on one side, the nanocarbon layer 13, the composite conductive layer 11, and the first porous layer 12 can be formed integrally. Therefore, even if the layer containing the nanocarbon material, particularly the nanocarbon layer 13 having a high concentration of the nanocarbon material, is provided, the first porous layer 12 has sufficient mechanical strength, and thus is formed of these layers. Since the electrode 1 also has sufficient mechanical strength as a whole, the electrode 1 can be less likely to be damaged and the electrode 1 can be manufactured more easily.
  • the nanocarbon layer 13 itself having a high concentration of the nanocarbon material has a property that mechanical strength is not sufficient and is easily damaged, it may be laminated and integrated with the composite conductive layer 11 and the first porous layer 12. Since the nanocarbon layer 13 is reinforced by at least the first porous layer 12 by being formed, it is possible to increase mechanical strength and prevent damage.
  • the nanocarbon layer 13 composed only of the nanocarbon material and the composite conductive layer 11 composed of both the nanocarbon material and the carbon fiber are integrated.
  • the nanocarbon material contained in the nanocarbon layer 13 is easily entangled and retained by the carbon fibers of the composite conductive layer 11, so that the nanocarbon material flows out (separates) from the nanocarbon layer 13. ) Is effectively suppressed, it is possible to prevent the deterioration of the electrode.
  • the composite conductive layer 11, the first porous layer 12, the nanocarbon layer 13, and the second porous layer 15 will be described in detail below.
  • the composite conductive layer 11 is configured to include both a nanocarbon material and carbon fibers having an average fiber diameter of 1 ⁇ m or more. As a result, the reactivity is enhanced by the nanocarbon material having a relatively large surface area, while the nanocarbon material is held by the carbon fibers, so that the nanocarbon material can be prevented from flowing out of the electrode 1.
  • the nanocarbon material may include a carbon material having a size of less than 1 ⁇ m in at least one of the three dimensions, and among them, from the viewpoint of acid resistance and oxidation resistance, the average fiber It preferably contains carbon nanotubes having a diameter of less than 1 ⁇ m.
  • the nanocarbon material in addition to carbon nanotubes, for example, carbon nanofibers and graphene can be cited.
  • the average fiber diameter of the carbon nanotubes is preferably 1 nm to 300 nm, more preferably 10 nm to 200 nm, and further preferably 15 nm to 150 nm.
  • the average fiber length of the carbon nanotubes is preferably 0.1 ⁇ m to 30 ⁇ m, more preferably 0.5 ⁇ m to 25 ⁇ m, still more preferably 0.5 ⁇ m to 20 ⁇ m. At this time, a plurality of types of carbon nanotubes having different average fiber diameters or average fiber lengths may be mixed.
  • the carbon fibers contained in the composite conductive layer 11 have a large average fiber diameter of 1 ⁇ m or more.
  • carbon fibers having an average fiber diameter of 1 ⁇ m or more it is possible to form a larger void inside the composite conductive layer 11 and reduce the pressure loss when the electrolytic solution is passed through the electrodes. .. Further, the effect of improving the conductivity and mechanical strength of the composite conductive layer 11 can be expected.
  • carbon fibers having an average fiber diameter of 200 ⁇ m or less the nanocarbon material is easily entangled and retained in the carbon fibers, so that the nanocarbon materials included in the composite conductive layer 11 and the adjacent nanocarbon layer 13 are The outflow to the electrolyte can be suppressed.
  • the average fiber diameter of the carbon fibers is preferably 1 ⁇ m to 200 ⁇ m, more preferably 2 ⁇ m to 100 ⁇ m, still more preferably 5 ⁇ m to 30 ⁇ m.
  • the average fiber length of the carbon fibers is preferably 0.01 mm to 20 mm, more preferably 0.05 mm to 10 mm, further preferably 0.1 mm to 8 mm.
  • the average fiber diameter and average fiber length of carbon nanotubes and carbon fibers, which are nanocarbon materials are randomly determined for each type of fibers (carbon nanotubes and carbon fibers) using a transmission electron microscope (TEM). It is possible to measure the diameters of 100 or more fibers and obtain the arithmetic mean value of the measured values.
  • TEM transmission electron microscope
  • the composite conductive layer 11 has a fine structure made of nanocarbon material and carbon fiber.
  • This fine structure is a structure in which a nanocarbon material is attached to the surface of carbon fiber.
  • the carbon nanotube which is a nanocarbon material, may have a structure that spans a plurality of carbon fibers.
  • the composite conductive layer 11 has a carbon fiber content of preferably 90 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less based on 100 parts by mass of the total of the nanocarbon material and the carbon fiber. .. Further, the lower limit of the content of the carbon fiber is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and further preferably 40 parts by mass or more based on 100 parts by mass of the total of the nanocarbon material and the carbon fiber. By setting the content of the carbon fibers in the composite conductive layer 11 within this range, it is possible to improve the reactivity in the composite conductive layer 11 and reduce the pressure loss when the electrolytic solution is passed through the electrodes. ..
  • the thickness (thickness dimension) of the composite conductive layer 11 in a dry state is preferably 0.01 mm to 0.20 mm, more preferably 0.01 mm to 0.15 mm, further preferably 0.02 mm to 0.15 mm, and further It is preferably 0.02 mm to 0.10 mm.
  • the thickness of the composite conductive layer 11 is preferably 0.01 mm or more, the reactivity in the composite conductive layer 11 is enhanced, and thus the charge/discharge efficiency of the redox flow battery can be enhanced.
  • the composite conductive layer 11 having a thickness of 0.01 mm or more integrally with the nanocarbon layer 13 as a layer constituting the laminated structure of the electrode 1 the nanocarbon material contained in the nanocarbon layer 13 is a composite material.
  • the nanocarbon layer 13 can be easily held by the electrode 1.
  • the thickness of the composite conductive layer 11 to 0.20 mm or less, when this electrode is used in a redox flow battery, the protons generated by charge and discharge move quickly to the ion exchange membrane, and The resistivity can be reduced.
  • the first porous layer 12 is provided on one surface of both surfaces of the composite conductive layer 11, and is composed of carbon fibers having an average fiber diameter of 1 ⁇ m or more.
  • the first porous layer 12 is a layer having a small pressure loss when the electrolytic solution is passed through the electrode, and has a high mechanical strength that can be easily handled alone.
  • the carbon fiber contained in the first porous layer 12 has a large average fiber diameter of 1 ⁇ m or more, similar to that contained in the composite conductive layer 11. Thereby, a larger void can be formed inside the first porous layer 12, so that the pressure loss when the electrolytic solution is passed through the electrode can be reduced.
  • the average fiber diameter of the carbon fibers contained in the first porous layer 12 is preferably 1 ⁇ m to 200 ⁇ m, more preferably 2 ⁇ m to 100 ⁇ m, still more preferably 5 ⁇ m to 30 ⁇ m.
  • the carbon fibers forming the first porous layer 12 include a woven fabric of relatively long fibers, a non-woven fabric (felt) woven without woven fibers, and a sheet of paper made by filtering relatively short fibers. Of these, any form may be used. At this time, as the average fiber length of the carbon fibers, it is preferable to adopt a length usually used in each form.
  • the thickness (thickness dimension) of the first porous layer 12 in a dry state is preferably 0.05 mm to 0.30 mm, more preferably 0.07 mm to 0.25 mm, further preferably 0.10 mm to 0.20 mm. Is. By setting the thickness of the first porous layer 12 in the above range, it is possible to sufficiently maintain the mechanical strength of the electrode for a redox flow battery and to suppress an increase in cell resistivity when used in a redox flow battery. ..
  • the composite conductive layer 11 and the first porous layer 12 may not be distinguished by a clear boundary, and the composite conductive layer 11 and the first porous layer 12 may be integrated.
  • the layer in which the composite conductive layer 11 and the first porous layer 12 are integrated has a region containing no nanocarbon material on one side in the thickness direction and a region containing nanocarbon material on the other side. May be configured to have. At this time, the region containing the nanocarbon material corresponds to the composite conductive layer 11, and the region not containing the nanocarbon material corresponds to the first porous layer 12.
  • the nanocarbon layer 13 is provided on the surface of the composite conductive layer 11 opposite to the first porous layer 12, and is made of a nanocarbon material. Since the nanocarbon layer 13 is an aggregate of nanocarbon materials having a nano size, it has a large surface area per unit volume and a large number of active points, as compared with other layers, and thus a layer where electrode reaction is actively performed. Is. On the other hand, since the nanocarbon layer 13 is inferior in mechanical strength to the other layers, in the present embodiment, the nanocarbon layer 13 is composed of the composite conductive layer 11 and the carbon fiber as the first porous layer. 12 and an integral laminated structure. Thereby, the insufficient strength of the nanocarbon layer 13 can be sufficiently compensated by the integration of the composite conductive layer 11 and the first porous layer 12 having high mechanical strength.
  • the nanocarbon material forming the nanocarbon layer 13 may include a carbon material having a size of less than 1 ⁇ m in at least one of the three dimensions. Among them, from the viewpoint of acid resistance and oxidation resistance, it is preferable to include carbon nanotubes having an average fiber diameter of less than 1 ⁇ m.
  • the average fiber diameter and average fiber length of the carbon nanotubes can be the same as those included in the composite conductive layer 11. At this time, a plurality of types of carbon nanotubes having different average fiber diameters or average fiber lengths may be mixed.
  • the dry thickness (thickness dimension) of the nanocarbon layer 13 is preferably 0.01 mm to 0.20 mm, more preferably 0.01 mm to 0.15 mm, and further preferably 0.01 mm to 0.10 mm. ..
  • the thickness of the nanocarbon layer 13 is preferably 0.01 mm to 0.20 mm, more preferably 0.01 mm to 0.15 mm, and further preferably 0.01 mm to 0.10 mm. ..
  • the thickness of the nanocarbon layer 13 is preferably 0.01 mm to 0.20 mm, more preferably 0.01 mm to 0.15 mm, and further preferably 0.01 mm to 0.10 mm. ..
  • the ratio (a/b) of the thickness dimension (a) of the composite conductive layer 11 to the thickness dimension (b) of the first porous layer 12 is preferably 0. 10 to 2.0, more preferably 0.20 to 1.5, still more preferably 0.20 to 1.0.
  • the ratio (c/b) of the thickness dimension (c) of the nanocarbon layer 13 to the thickness dimension (b) of the first porous layer 12 is preferably 0.05 to 2.0, more preferably 0.
  • the range is 0.05 to 1.0, and more preferably 0.2 to 1.0.
  • the nanocarbon layer 13 and the composite conductive layer 11 may not be distinguished by a clear boundary, and the nanocarbon layer 13 and the composite conductive layer 11 may be integrated. It is preferable that the layer in which the nanocarbon layer 13 and the composite conductive layer 11 are integrated has a region made of a nanocarbon material in at least a part of one side in the thickness direction. At this time, it is more preferable that the region made of the nanocarbon material has a layer having a constant thickness.
  • the boundary between them is unclear. May become integrated. Even in that case, since the integrated nanocarbon layer 13 and the composite conductive layer 11 are supported by the first porous layer 12, the mechanical strength of the redox flow battery electrode 1 can be increased.
  • the second porous layer 15 is a layer that is located on a surface opposite to the composite conductive layer 11 on both surfaces of the nanocarbon layer 13, and is composed of carbon fibers having an average fiber diameter of 1 ⁇ m or more. Can be provided.
  • the second porous layer 15 is a layer having a small pressure loss when the electrolytic solution is passed through the electrode, and has a high mechanical strength that can be easily handled by itself.
  • the electrolytic solution spreads inside the second porous layer 15, so that the nanocarbon layer of the second porous layer 15 is included.
  • the electrolytic solution can be spread over almost the entire surface adjacent to 13. As a result, the electrolytic solution flows more uniformly and vertically to the surface of the nanocarbon layer 13, so that the liquid permeability in the redox flow battery electrode 1 can be further enhanced.
  • the same carbon fiber contained in the first porous layer 12 can be used as the carbon fiber contained in the second porous layer 15 as the carbon fiber contained in the second porous layer 12.
  • the thickness (thickness dimension) of the second porous layer 15 in a dry state is preferably 0.10 mm to 0.50 mm, more preferably 0.15 mm to 0.40 mm, further preferably 0.20 mm to 0.40 mm. Is. By setting the thickness of the second porous layer 15 within the range of 0.10 mm to 0.50 mm, the electrolytic solution spreads uniformly inside the second porous layer 15, so that the liquid permeability of the electrode 1 is improved. You can
  • FIG. 2 is a schematic configuration diagram showing an example of the configuration of the redox flow battery according to the present embodiment, and shows an example in which a vanadium compound is used as an active material.
  • the redox flow battery 2 according to the present embodiment is used in a form called a battery cell stack in which the battery cell 6 is used as a minimum unit, or a single unit of the battery cell 6 is stacked, and an electrolytic solution is circulated in the battery cell 6. Charge and discharge.
  • the redox flow battery 2 includes a positive electrode cell 41 having a positive electrode 1a incorporated therein, a negative electrode cell 51 having a negative electrode 1b incorporated therein, and a positive electrode 1a and a negative electrode 1b interposed therebetween to separate the cells.
  • the battery cell 6 having the ion exchange membrane 60 that allows predetermined ions to permeate is the main component.
  • the redox flow battery 2 uses the above-mentioned redox flow battery electrode 1 for one or both of the positive electrode 1a and the negative electrode 1b.
  • the redox flow battery electrode 1 is disposed between the ion exchange membrane 60 and the electrode plate 16a.
  • the redox flow battery electrode 1 is used as the negative electrode 1b, the redox flow battery electrode 1 is disposed between the ion exchange membrane 60 and the electrode plate 16b.
  • the electrode 1 for redox flow battery is provided so that the surface of the first porous layer 12 opposite to the composite conductive layer 11 faces the ion exchange membrane 60.
  • the surface of the second porous layer 15 opposite to the nanocarbon layer 13 faces the electrode plates 16a and 16b.
  • the electrode 1 (the positive electrode 1a or the negative electrode 1b) is provided such that one surface of the second porous layer 15 faces the electrode plates 16a and 16b.
  • the surface opposite to the composite conductive layer 11 may be provided so as to face the electrode plates 16a and 16b.
  • the surface opposite to the nanocarbon layer faces the ion exchange membrane 60.
  • the electrode 1 for a redox flow battery described above as one or both of the positive electrode 1a and the negative electrode 1b, the charge/discharge efficiency of the electrolytic solution in the redox flow battery 2 is increased, and the redox flow battery 2 is used.
  • the cell resistivity of can be lowered.
  • the active material contained in the electrolytic solution on the positive electrode side and the negative electrode side of the redox flow battery 2 is, for example, one of a vanadium compound, a molybdenum compound, a tin compound, an iron compound, a chromium compound, a manganese compound, a titanium compound, and a zinc compound.
  • a vanadium compound as an active material in both the positive electrode side and negative electrode side electrolytic solutions, and also include a manganese compound in the positive electrode side electrolytic solution as an active material, and a titanium compound as an active material on the negative electrode side. It is also preferable to include it in the electrolytic solution.
  • a known cation exchange membrane can be used as the ion exchange membrane 60 used in the redox flow battery 2.
  • a perfluorocarbon polymer having a sulfonic acid group a hydrocarbon-based polymer compound having a sulfonic acid group, a polymer compound doped with an inorganic acid such as phosphoric acid, a part of which is a proton-conductive functional group.
  • perfluorocarbon polymers having a sulfonic acid group are preferable, and Nafion (registered trademark) is more preferable.
  • a conductive material containing carbon can be used. More specifically, a conductive resin composed of graphite and an organic polymer compound, or a conductive resin in which a part of graphite is replaced with one or both of carbon black and diamond-like carbon, and carbon and the resin are kneaded.
  • An example of the molded material is a molded material. Of these, it is preferable to use a molding material obtained by kneading and molding carbon and resin.
  • the electrode plates 16a and 16b may be provided with a flow path of an electrolytic solution which communicates with the outside of the redox flow battery electrode 1. More specifically, it is preferable that a groove portion including a groove or a recess for improving the liquid permeability of the electrolytic solution is formed on the electrode side. Only one groove or recess may be formed in the electrode plates 16a and 16b as in the groove portion 161 shown in FIG. 1, and a plurality of grooves or recesses may be formed on the surface facing the redox flow battery electrode 1. May be. Further, the size of the groove or the dent is not particularly limited. Further, the electrode plates 16a and 16b may exchange electricity via a current collector plate (not shown).
  • the redox flow battery 2 includes a positive electrode electrolytic solution tank 42 that stores a positive electrode electrolytic solution that is circulated and supplied to the positive electrode cell 41, a positive electrode forward pipe 43 that sends the positive electrode electrolytic solution from the positive electrode electrolytic solution tank 42 to the positive electrode cell 41, and a positive electrode electrolytic solution. And a positive electrode return pipe 44 for returning from the positive electrode cell 41 to the positive electrode electrolyte tank 42.
  • a pump 45 for circulating the positive electrode electrolytic solution is arranged in the positive electrode outward piping 43.
  • the redox flow battery 2 includes a negative electrode electrolytic solution tank 52 that stores a negative electrode electrolytic solution that is circulated and supplied to the negative electrode cell 51, and a negative electrode outward piping 53 that sends the negative electrode electrolytic solution from the negative electrode electrolytic solution tank 52 to the negative electrode cell 51. And a negative electrode return pipe 54 for returning the negative electrode electrolytic solution from the negative electrode cell 51 to the negative electrode electrolytic solution tank 52.
  • a pump 55 for circulating the negative electrode electrolytic solution is arranged in the negative electrode outward piping 53.
  • the electrolytic solution in the positive electrode electrolytic solution tank 42 is sent to the battery cell 6 (more strictly, the positive electrode cell 41) through the positive electrode outward piping 43 by operating the pump 45. ..
  • the positive electrode electrolytic solution sent to the battery cell 6 is discharged upward through the inside of the battery cell 6 and returned to the positive electrode electrolytic solution tank 42 through the positive electrode return pipe 44, whereby the positive electrode electrolytic solution is directed in the direction of arrow A in the figure. Circulate.
  • the electrolytic solution in the negative electrode electrolytic solution tank 52 is sent to the battery cell 6 (more strictly, the negative electrode cell 51) through the negative electrode outward pipe 53 by operating the pump 55.
  • the electrolytic solution sent to the battery cell 6 is circulated in the direction of arrow B in the figure by being discharged upward through the inside of the battery cell 6 and returned to the negative electrode electrolytic solution tank 52 through the negative electrode return pipe 54.
  • the battery cell 6 of the redox flow battery 2 has been described as a single cell, but it may be configured in a form called a cell stack in which a plurality of single cells are stacked (not shown).
  • the polar plates 16a and 16b of the adjacent battery cells 6 in the stacked cell stacks may be formed by one bipolar plate, and the stacked structure of the electrode 1 may be provided on each of both surfaces thereof.
  • the conductive sheet material for electrodes is a conductive sheet material used for electrodes, particularly for the above-described redox flow battery electrode 1.
  • This conductive sheet material is a composite conductive layer 11 composed of both a nanocarbon material and carbon fibers, and a first porous layer composed of carbon fibers and located on one surface of both surfaces of the composite conductive layer 11. 12 and a nanocarbon layer 13 located on the other surface of the composite conductive layer and made of a nanocarbon material.
  • the conductive sheet material for electrodes By forming the conductive sheet material for electrodes into the above layer structure, it is possible to obtain a structure in which the first porous layer is arranged on one surface of the composite conductive layer and the nanocarbon layer is arranged on the other surface. At the same time, the first porous layer ensures the mechanical strength that can withstand the production of the laminated structure, so that the conductive sheet material for electrodes is less likely to be damaged and the production of electrodes is facilitated. Therefore, it is possible to contribute to the reduction of the cell resistivity of the redox flow battery, and it is possible to more easily obtain an electrode having high mechanical strength.
  • a dispersion containing a nanocarbon material and carbon fibers is applied to one surface of the first porous layer 12 and dried to form the composite conductive layer 11.
  • a step of forming a nanocarbon layer 13 by applying a dispersion liquid containing only a nanocarbon material to one of both surfaces of the composite conductive layer 11 opposite to the first porous layer 12 and then drying it.
  • the composite conductive layer 11 is integrated with the first porous layer 12 by forming a composite conductive layer 11 by applying a dispersion liquid containing a nanocarbon material and carbon fibers on one surface of the first porous layer 12. It becomes possible to change. Further, the nanocarbon layer 13 is formed by applying the dispersion liquid containing only the nanocarbon material to the surface opposite to the first porous layer 12 of both surfaces of the composite conductive layer 11 to form the nanocarbon layer 13. Can be integrated with the composite conductive layer 11 and the first porous layer 12. Accordingly, when the composite conductive layer 11 or the nanocarbon layer 13 that is a thin layer containing carbon nanotubes is integrally provided on the first porous layer 12, damage to these layers is unlikely to occur, and thus the redox flow is prevented. The production of the battery electrode can be made easier.
  • the nanocarbon dispersion liquid containing the nanocarbon material used in the manufacturing method according to the present embodiment can be obtained by dispersing the nanocarbon material in the dispersion medium.
  • the nanocarbon material can include a carbon material having a size of less than 1 ⁇ m in at least one of the three dimensions. Among them, from the viewpoint of acid resistance and oxidation resistance, it is preferable to include carbon nanotubes having an average fiber diameter of less than 1 ⁇ m.
  • the dispersion medium is not particularly limited, and water can be used, for example.
  • a dispersant When dispersing the nanocarbon material in the dispersion medium, it is preferable to add a dispersant to the dispersion medium, which can facilitate uniform dispersion of the nanocarbon material.
  • a dispersant a known dispersant can be used, and for example, a water-soluble conductive polymer can be used.
  • the method for preparing the nanocarbon dispersion by dispersing the nanocarbon material is not particularly limited, and examples thereof include a method using a ball mill, a paint shaker, ultrasonic waves, a jet mill, and the like. Among them, the method using ultrasonic waves or a wet jet mill is preferable in that the nanocarbon material can be uniformly dispersed while suppressing damage to the nanocarbon material.
  • the composite dispersion liquid containing a nanocarbon material and carbon fibers used in the manufacturing method according to the present embodiment can be obtained, for example, by further dispersing carbon fibers in the above-mentioned nanocarbon dispersion liquid. Further, a composite dispersion liquid may be obtained by simultaneously dispersing the nanocarbon material and the carbon fiber in the dispersion medium.
  • carbon fibers having an average fiber diameter of 1 ⁇ m or more can be used.
  • the method of dispersing the carbon fiber in the nanocarbon dispersion is not particularly limited, and examples thereof include a method using ultrasonic waves, a ball mill, and a magnetic stirrer.
  • the first porous layer 12 the one made of carbon fibers having an average fiber diameter of 1 ⁇ m or more as described above is used.
  • a woven fabric, felt, paper or the like made of carbon fiber having an average fiber diameter of 1 ⁇ m or more and processed into a predetermined size can be used.
  • the composite dispersion liquid As a means for applying the composite dispersion liquid to the first porous layer 12, for example, a roll coater method or a spray method can be used. Then, after applying the composite dispersion liquid to the first porous layer 12, the dispersion medium is distilled off to form the composite conductive layer 11 on one surface of the first porous layer 12.
  • a nanocarbon layer 13 is formed by applying a nanocarbon dispersion liquid to the surface of the composite conductive layer 11 located on the opposite side of the first porous layer 12 from both surfaces. To do.
  • the nanocarbon layer 13 can be formed on the composite conductive layer 11 by applying the nanocarbon dispersion liquid to the composite conductive layer 11 and then distilling the dispersion medium. In this way, a laminate having the three layers of the first porous layer 12, the composite conductive layer 11 and the nanocarbon layer 13 can be obtained.
  • the obtained laminated body is processed into a predetermined size if necessary, and then, as shown in FIG. 3(C), on a surface of the nanocarbon layer 13 opposite to the composite conductive layer 11, the surface is located. It is preferable to stack the second porous layer 15.
  • the second porous layer 15 may be held by the electrode plate 16 as shown in FIG. In this case, for the redox flow battery, by stacking a laminate having the nanocarbon layer 13, the composite conductive layer 11 and the first porous layer 12 in this order on the second porous layer 15 held by the electrode plate 16. The electrode 1 can be obtained.
  • the second porous layer 15 as with the first porous layer 12, a layer made of carbon fiber having an average fiber diameter of 1 ⁇ m or more is used.
  • the second porous layer 15 is disposed so as to face the nanocarbon layer 13 of the laminated body having the first porous layer 12, the composite conductive layer 11 and the nanocarbon layer 13, and is press-formed while being heated if necessary. Thereby, it can be integrated with the laminated body having the first porous layer 12, the composite conductive layer 11, and the nanocarbon layer 13.
  • the press pressure and heating temperature during press molding can be determined by preliminary experiments.
  • the redox flow battery electrode 1 can be manufactured by heating at a temperature of 50° C. to 250° C. under a pressure of 10 MPa to 20 MPa.
  • the nanocarbon layer 13 may be laminated with the second porous layer 15 not held by the electrode plate 16.
  • the conductive sheet material for electrodes is obtained by laminating the second porous layer 15.
  • You can The redox flow battery electrode 1 can be obtained by processing the obtained electrode conductive sheet material into a predetermined size and then attaching the electrode plate 16 to the second porous layer 15 if necessary.
  • the redox flow battery electrode 1 thus produced can be incorporated into the redox flow battery 2 shown in FIG. 2 by a conventional method.
  • the redox flow battery electrode 1 is used as the positive electrode 1a
  • the redox flow battery electrode 1 is provided between the ion exchange membrane 60 and the positive electrode plate 16a.
  • the redox flow battery electrode 1 is used as the negative electrode 1b
  • the redox flow battery electrode 1 is provided between the ion exchange membrane 60 and the negative electrode plate 16b.
  • Example 1 Preparation of Dispersion Liquid Containing Nanocarbon Material A solution was prepared by dissolving 0.3 mg of polyisothionaphthenesulfonic acid, which is a water-soluble conductive polymer, as a dispersant in 30 mL of pure water. To this solution, 0.4 g of VGCF (registered trademark)-H (average fiber diameter: 150 nm, average fiber length: 15 ⁇ m) manufactured by Showa Denko Co., Ltd. as a carbon nanotube, which is a nanocarbon material, was added, and the mixture was ultrasonically cleaned for 30 minutes. By performing the dispersion treatment, a dispersion liquid (dispersion liquid A) of the nanocarbon material was obtained.
  • VGCF registered trademark
  • Dispersion Liquid Containing Nanocarbon Material and Carbon Fiber A solution was prepared by dissolving 0.3 mg of polyisothionaphthenesulfonic acid, which is a water-soluble conductive polymer, as a dispersant in 30 mL of pure water. In this solution, 0.3 g of VGCF (registered trademark)-H (average fiber diameter 150 nm, average fiber length 15 ⁇ m) manufactured by Showa Denko KK as carbon nanotubes, which is a nanocarbon material, and carbon fiber donacarb made by Osaka Gas Chemicals, Inc.
  • VGCF registered trademark
  • H average fiber diameter 150 nm, average fiber length 15 ⁇ m
  • the content of carbon fiber in this dispersion B is 40 parts by mass when the total content of the nanocarbon material and the carbon fiber is 100 parts by mass.
  • a carbon paper having a size of 100 mm ⁇ 100 mm and a thickness of 0.19 mm (manufactured by SGL Carbon Co., model number GDL-29AA) is arranged, and the nanocarbon material and the carbon fiber described above are arranged.
  • the dispersion liquid B containing was applied by using a spray as a coating means. Then, it dried and formed the composite conductive layer in the 1st porous layer.
  • the thickness obtained by subtracting the thickness b of the first porous layer from the total thickness of the first porous layer on which the composite conductive layer is formed was determined as the thickness a of the composite conductive layer.
  • the content of carbon fibers in the composite conductive layer is the content of carbon fibers contained in dispersion B when the total content of the nanocarbon material and carbon fibers contained in dispersion B is 100 parts by mass ( Mass part).
  • the composite conductive layer formed on the first porous layer was coated with the above-mentioned dispersion liquid of the nanocarbon material using a spray as a coating means. Then, it was dried to form a nanocarbon layer on the composite conductive layer, thereby obtaining a conductive sheet material for electrodes.
  • the thickness obtained by subtracting the thickness of the first porous layer and the composite conductive layer from the thickness of the electrode conductive sheet material was determined as the thickness c of the nanocarbon layer.
  • the electrode plate is made of a flat-plate molding material obtained by kneading and molding carbon and plastic, and has a concave portion on its main surface, and the concave portion is surrounded by a peripheral wall.
  • the size of the recess is 49 mm ⁇ 49 mm ⁇ depth 0.37 mm (that is, the height of the peripheral wall surrounding the recess is 0.37 mm), and the width of the peripheral wall surrounding the recess is 1 mm.
  • the size of the recess is such that the second porous layer described below fits into the recess without any gap.
  • a plurality of grooves are formed in parallel with each other on the surface of the electrode plate facing the electrode.
  • the width of each groove formed in the electrode plate is 0.5 mm
  • the depth of each groove is 1.0 mm
  • the interval between the grooves is 0.5 mm.
  • the second porous layer carbon paper having a size of 49 mm ⁇ 49 mm (manufactured by Toray Industries, Inc., model number TGP-H-120, thickness 0.37 mm) was used, and this second porous layer was used as a concave portion of the electrode plate. Mated.
  • the conductive sheet material for electrodes is cut into a size of 50 mm ⁇ 50 mm, and the conductive sheet material for electrodes is arranged on the electrode plate so that the nanocarbon layer of the conductive sheet material for electrodes faces the second porous layer.
  • the electrodes thus prepared were used as a positive electrode and a negative electrode, respectively, and these electrodes were arranged such that the first porous layer side of the electrodes faced the ion exchange membrane.
  • Nafion (registered trademark) 212 model number
  • a gold-plated brass plate was placed as a current collector plate on the outside of the two electrode plates to form a single cell of a redox flow battery.
  • the obtained redox flow batteries were evaluated for charge/discharge characteristics and durability.
  • An aqueous solution containing vanadium ions (IV valence) and sulfuric acid was introduced into the positive electrode side, and an aqueous solution containing vanadium ions (III valence) and sulfuric acid was introduced into the negative electrode side as electrolyte solutions, and 25 mL of each electrolyte solution was circulated by a tube pump.
  • the flow rate of the electrolytic solution was set to 64 mL/min.
  • the current during charge/discharge was 2.5 A (100 mA/cm 2 ), the charge stop voltage was 1.75 V, and the discharge stop voltage was 1.00 V.
  • the cell resistivity was a value obtained by calculating the charge average voltage and the discharge average voltage at the fifth charge/discharge cycle and using the following formula.
  • Cell resistivity [ ⁇ cm 2 ] (charge average voltage [V] ⁇ discharge average voltage [V]) ⁇ electrode area [cm 2 ] ⁇ (2 ⁇ charge current [A])
  • the charge/discharge efficiency was measured at the fifth charge/discharge cycle.
  • the redox flow battery was disassembled, the second porous layer and the electrode plate were removed from the electrodes, and the presence or absence of cracks in the nanocarbon layer and the composite conductive layer was visually checked. Confirmed by.
  • those in which cracks are not observed in both the nanocarbon layer and the composite conductive layer are " ⁇ "
  • one of the nanocarbon layer and the composite conductive layer or Those having cracks on both sides were marked with "x”.
  • Example 2 In "2. Preparation of dispersion containing nanocarbon material and carbon fiber", a single cell of a redox flow battery was constructed in the same manner as in Example 1 except that the amount of carbon fiber added was 0.4 g. At this time, the content of the carbon fibers in the dispersion B is 57 parts by mass when the total content of the nanocarbon material and the carbon fibers is 100 parts by mass. Charge/discharge characteristics and durability of the obtained redox flow battery were evaluated in the same manner.
  • Example 3 In “3. Formation of composite conductive layer", carbon paper having a size of 100 mm x 100 mm and a thickness of 0.11 mm (manufactured by Toray Industries, Inc., model number TGP-H-30) was used as the first porous layer, except that A single cell of a redox flow battery was constructed in the same manner as in Example 2. Charge/discharge characteristics and durability of the obtained redox flow battery were evaluated in the same manner.
  • Example 4 In “1. Preparation of dispersion containing nanocarbon material”, addition of VGCF (registered trademark)-H (average fiber diameter 150 nm, average fiber length 15 ⁇ m) manufactured by Showa Denko KK, which is a nanocarbon material (carbon nanotube) The amount was 0.5 g. Moreover, in “2. Preparation of dispersion containing nanocarbon material and carbon fiber”, VGCF (registered trademark)-H (average fiber diameter 150 nm, average, manufactured by Showa Denko KK, which is a nanocarbon material (carbon nanotube), is used. The amount of the fiber length (15 ⁇ m) added was 0.4 g.
  • the content of the carbon fiber in the dispersion B is 50 parts by mass when the total content of the nanocarbon material and the carbon fiber is 100 parts by mass. Except for these, a single cell of a redox flow battery was constructed in the same manner as in Example 3. Charge/discharge characteristics and durability of the obtained redox flow battery were evaluated in the same manner.
  • Example 5 In “1. Preparation of Dispersion Liquid Containing Nanocarbon Material” and “2. Preparation of Dispersion Liquid Containing Nanocarbon Material and Carbon Fiber”, instead of VGCF-H, graphene (xGnP-C- manufactured by XG Science Co., Ltd. A single cell of a redox flow battery was constructed in the same manner as in Example 1 except that 300) was used. Charge/discharge characteristics and durability of the obtained redox flow battery were evaluated in the same manner.
  • Example 1 A single cell of a redox flow battery was constructed by using the same conductive sheet as in Example 13 of WO 2016/104613.
  • the conductive sheet described in Example 13 of WO2016/104613 when the total content of the nanocarbon material and the carbon fiber is 100 parts by mass, VGCF-H of 45 is used as the carbon nanotube. 5 parts by mass of VGCF (registered trademark)-X (average fiber diameter 15 nm, average fiber length 3 ⁇ m, manufactured by Showa Denko KK), and 50 parts by mass of Dona Carbo Chop SG-249 as carbon fiber. Contains.
  • This conductive sheet was cut into a size of 50 mm ⁇ 50 mm, and the conductive sheet was placed on the electrode plate so that one surface of the conductive sheet faced the second porous layer. Then, the first porous layer was cut into a size of 50 mm ⁇ 50 mm, and the first porous layer was arranged so as to overlap with the other surface of the conductive sheet.
  • a single cell of a redox flow battery was constructed in the same manner as in Example 1 except for the above. That is, the single cell of the redox flow battery configured in Comparative Example 1 does not have the nanocarbon layer. Charge/discharge characteristics and durability of the obtained redox flow battery were evaluated in the same manner.
  • Comparative example 2 A single cell of a redox flow battery was constructed in the same manner as in Comparative Example 1 except that carbon paper having a size of 50 mm ⁇ 50 mm (Toray Industries, Inc., model number TGP-H-30) was used as the first porous layer. did. That is, the single cell of the redox flow battery configured in Comparative Example 2 also does not have the nanocarbon layer as in Comparative Example 1. Charge/discharge characteristics and durability of the obtained redox flow battery were evaluated in the same manner.
  • Table 1 shows various conditions in Examples 1 to 5 and Comparative Examples 1 to 2, cell resistivity, charge/discharge efficiency (Coulomb efficiency), and durability.
  • the electrodes of Examples 1 to 5 were located on one of both surfaces of the composite conductive layer and a composite conductive layer composed of both a nanocarbon material and carbon fibers having an average fiber diameter of 1 ⁇ m or more.
  • Comparative Example 1 that does not have a nanocarbon layer by including the first porous layer that is configured and the nanocarbon layer that is located on the other surface of both surfaces of the composite conductive layer and that is formed of a nanocarbon material It was found that the cell resistivity of the redox flow battery was reduced as compared with the No. 2 electrode. Further, the total thickness of the composite conductive layer and the nanocarbon layer forming the electrodes of Examples 1 to 5 should be smaller than the thickness of the composite conductive layer forming the electrodes of Comparative Examples 1 and 2 having no nanocarbon layer. Nonetheless, since the electrode material was not damaged, it was found that the electrode material having such a laminated structure is less likely to be damaged, and as a result, the electrode is easily manufactured. ..
  • the electrodes of Examples 1 to 5 do not cause cracks after charge and discharge, so that the mechanical strength of the electrodes can be increased. confirmed.

Abstract

Provided are: an electrode for a redox flow battery which can contribute to reduction in cell resistance of the redox flow battery and which has sufficiently high mechanical strength; a method for manufacturing the same; a redox flow battery; and a conductive sheet material for an electrode. An electrode 1 for a redox flow battery includes: a composite conductive layer 11 formed by both a nanocarbon material and carbon fibers having an average fiber diameter of 1 μm or greater; a first porous layer 12 positioned on one surface from between the two surfaces of the composite conductive layer 11 and formed by carbon fibers; and a nanocarbon layer 13 positioned on the other surface of the composite conductive layer 11 and formed by a nanocarbon material.

Description

レドックスフロー電池用電極及びその製造方法、並びにレドックスフロー電池及び電極用導電シート材料Redox flow battery electrode and method of manufacturing the same, and redox flow battery and conductive sheet material for electrode
　本発明は、電解液を循環させて充放電を行なうレドックスフロー電池用の電極及びその製造方法、並びに前記電極を有するレドックスフロー電池及び電極用導電シート材料に関する。 The present invention relates to an electrode for a redox flow battery in which an electrolyte is circulated for charging and discharging, a manufacturing method thereof, and a redox flow battery having the electrode and a conductive sheet material for the electrode.
　電力貯蔵用の電池として、種々の電池の開発が進められているが、電解液流通型の電池、いわゆるレドックスフロー電池がある。レドックスフロー電池は、正極と負極と両電極の間に介在される隔膜とを有する電池セルに、正極電解液及び負極電解液をそれぞれ供給循環し、電力変換器（例えば、交流／直流変換器等）を介して充放電を行なう。電解液には、通常酸化還元により価数が変化する金属イオン（活物質）を含有する水溶液が使用されている。レドックスフロー電池としては、例えば正極及び負極の活物質にバナジウム（Ｖ）を用いたバナジウム系レドックスフロー電池がよく知られている。 Various types of batteries are being developed as batteries for storing electricity, but there are so-called redox flow batteries, which are electrolyte flow batteries. A redox flow battery supplies and circulates a positive electrode electrolytic solution and a negative electrode electrolytic solution to and from a battery cell having a positive electrode, a negative electrode, and a diaphragm interposed between both electrodes, and a power converter (for example, an AC/DC converter or the like). ) To charge and discharge. As the electrolytic solution, an aqueous solution containing a metal ion (active material) whose valence changes by redox is usually used. As a redox flow battery, for example, a vanadium redox flow battery using vanadium (V) as an active material of a positive electrode and a negative electrode is well known.
　このようなレドックスフロー電池に用いられる電極の材料としては、カーボンナノチューブやカーボンファイバー等の炭素材料が用いられる。例えば、本出願人は、特許文献１において、レドックスフロー電池の電極材料として、平均繊維径が１μｍ以下のカーボンナノチューブと、平均繊維径が１μｍより大きいカーボンファイバーとを含む導電性シートと、平均繊維径が１μｍより大きいカーボンファイバーからなる多孔性シートが積層されてなるレドックスフロー電池用電極について提案した。 Carbon materials such as carbon nanotubes and carbon fibers are used as the material of the electrodes used in such a redox flow battery. For example, the present applicant discloses in Patent Document 1 that as an electrode material for a redox flow battery, a conductive sheet containing carbon nanotubes having an average fiber diameter of 1 μm or less and carbon fibers having an average fiber diameter of more than 1 μm, and an average fiber. We proposed an electrode for a redox flow battery in which porous sheets made of carbon fibers having a diameter larger than 1 μm are laminated.
国際公開第２０１６／１０４６１３号International Publication No. 2016/104613
　特許文献１に記載のレドックスフロー電池は、電気容量を大きくするとともに、セル抵抗率を低くし、また、電解液を電極に通液させた時の圧力損失を小さくしたものであるが、セル抵抗率等の性能においては十分であるとはいえず、さらに改善の余地があった。また、特許文献１では、レドックスフロー電池の電極の積層構造を作製する際に、カーボンナノチューブとカーボンファイバーとを含む導電性シートと、カーボンファイバーからなる多孔性シートの２層で積層構造を構成し、電極を作製していた。特に、導電性シートは、微細なカーボンナノチューブを含むために機械的強度が低くなり、それにより電極としての機械的強度も低くなる傾向があることから、機械的強度が十分に高いレドックスフロー電池用電極が求められていた。 The redox flow battery described in Patent Document 1 has a large electric capacity, a low cell resistivity, and a small pressure loss when an electrolytic solution is passed through the electrodes. It cannot be said that the performance such as the rate is sufficient, and there is room for further improvement. Further, in Patent Document 1, when a laminated structure of an electrode of a redox flow battery is produced, a laminated structure is constituted by two layers of a conductive sheet containing carbon nanotubes and carbon fibers and a porous sheet made of carbon fibers. , The electrodes were made. In particular, the conductive sheet tends to have low mechanical strength because it contains fine carbon nanotubes, and as a result, the mechanical strength as an electrode also tends to be low. Therefore, for a redox flow battery having sufficiently high mechanical strength. An electrode was sought.
　本発明の目的は、レドックスフロー電池のセル抵抗率の低減に寄与することができ、且つ機械的強度が十分に高いレドックスフロー電池用の電極及びその製造方法、並びにレドックスフロー電池及び電極用導電シート材料を提供することである。 An object of the present invention is to contribute to reduction of cell resistivity of a redox flow battery, and an electrode for a redox flow battery having sufficiently high mechanical strength, a method for producing the same, and a redox flow battery and a conductive sheet for an electrode. To provide the material.
　本発明者らは、レドックスフロー電池用の電極について、ナノカーボン材料及びカーボンファイバーの双方で構成される複合導電層の一方の面に、カーボンファイバーで構成される第１多孔質層を配置し、他方の面にナノカーボン材料で構成されるナノカーボン層を配置した、一体化されたレドックスフロー電池用電極とすることで、電極の機械的強度が高くなって破損が起こり難くなるとともに、レドックスフロー電池に用いたときにセル抵抗率が低くなることを見出し、本発明を完成するに至った。より具体的に、本発明は、以下のものを提供する。 The present inventors have arranged a first porous layer composed of carbon fibers on one surface of a composite conductive layer composed of both a nanocarbon material and carbon fibers for an electrode for a redox flow battery, An integrated redox flow battery electrode with a nanocarbon layer composed of a nanocarbon material on the other side makes the mechanical strength of the electrode higher and damages less likely to occur, as well as redox flow. The inventors have found that the cell resistivity is low when used in batteries, and have completed the present invention. More specifically, the present invention provides the following.
　（１）本発明は、ナノカーボン材料及び平均繊維径が１μｍ以上のカーボンファイバーの双方で構成される複合導電層と、前記複合導電層の両面のうち、一方の面に位置し、前記カーボンファイバーで構成される第１多孔質層と、前記複合導電層の他方の面に位置し、前記ナノカーボン材料で構成されるナノカーボン層とを有する、レドックスフロー電池用電極である。 (1) The present invention provides a composite conductive layer composed of both a nanocarbon material and a carbon fiber having an average fiber diameter of 1 μm or more, and one of the both surfaces of the composite conductive layer. An electrode for a redox flow battery, comprising: a first porous layer composed of and a nanocarbon layer located on the other surface of the composite conductive layer and composed of the nanocarbon material.
　（２）また、本発明は、前記ナノカーボン層および前記複合導電層の厚さ寸法は、いずれも０．０１ｍｍ～０．２０ｍｍであり、前記第１多孔質層の厚さ寸法は０．０５ｍｍ～０．３０ｍｍである、（１）に記載のレドックスフロー電池用電極である。 (2) Further, in the present invention, each of the nanocarbon layer and the composite conductive layer has a thickness of 0.01 mm to 0.20 mm, and the first porous layer has a thickness of 0.05 mm. The electrode for a redox flow battery according to (1), which has a thickness of up to 0.30 mm.
　（３）また、本発明は、前記ナノカーボン層の両面のうち、前記複合導電層と反対側の面に位置し、前記カーボンファイバーで構成される第２多孔質層をさらに有する、（１）又は（２）に記載のレドックスフロー電池用電極である。 (3) Further, the present invention further comprises a second porous layer which is located on a surface opposite to the composite conductive layer on both surfaces of the nanocarbon layer and which is composed of the carbon fiber. Alternatively, it is the electrode for a redox flow battery according to (2).
　（４）また、本発明は、前記第２多孔質層の厚さ寸法は０．１０ｍｍ～０．５０ｍｍである、（３）に記載のレドックスフロー電池用電極である。 (4) Further, the present invention is the electrode for a redox flow battery according to (3), wherein the thickness dimension of the second porous layer is 0.10 mm to 0.50 mm.
　（５）また、本発明は、前記第１多孔質層の厚さ寸法は、前記第２多孔質層の厚さ寸法よりも小さい、（３）又は（４）に記載のレドックスフロー電池用電極である。 (5) The present invention also provides the electrode for redox flow battery according to (3) or (4), wherein the thickness dimension of the first porous layer is smaller than the thickness dimension of the second porous layer. Is.
　（６）また、本発明は、前記ナノカーボン材料は、平均繊維径１μｍ未満のカーボンナノチューブを含む、（１）～（５）のいずれか一項に記載のレドックスフロー電池用電極である。 (6) Further, the present invention is the electrode for a redox flow battery according to any one of (1) to (5), wherein the nanocarbon material contains carbon nanotubes having an average fiber diameter of less than 1 μm.
　（７）また、本発明は、前記複合導電層が、前記ナノカーボン材料と前記カーボンファイバーの合計１００質量部に対し、前記カーボンファイバーを２０質量部～９０質量部含む、（１）～（６）のいずれか一項に記載のレドックスフロー電池用電極である。 (7) Further, in the present invention, the composite conductive layer contains 20 parts by mass to 90 parts by mass of the carbon fiber with respect to 100 parts by mass in total of the nanocarbon material and the carbon fiber, (1) to (6) ) It is an electrode for redox flow batteries as described in any one of the above.
　（８）また、本発明は、（１）～（７）のいずれか一項に記載のレドックスフロー電池用電極を有するレドックスフロー電池である。 (8) Further, the present invention is a redox flow battery having the electrode for redox flow battery according to any one of (1) to (7).
　（９）また、本発明は、イオン交換膜と極板との間に、（１）～（７）のいずれか一項に記載のレドックスフロー電池用電極を、前記第１多孔質層が前記イオン交換膜と対向するように備えるレドックスフロー電池である。 (9) Further, the present invention provides the redox flow battery electrode according to any one of (1) to (7) between the ion exchange membrane and the electrode plate, wherein the first porous layer is It is a redox flow battery provided so as to face an ion exchange membrane.
　（１０）また、本発明は、ナノカーボン材料及び平均繊維径が１μｍ以上のカーボンファイバーの双方で構成される複合導電層と、前記複合導電層の両面のうち、一方の面に位置し、前記カーボンファイバーで構成される第１多孔質層と、前記複合導電層の他方の面に位置し、前記ナノカーボン材料で構成されるナノカーボン層と、を有する、電極用導電シート材料である。 (10) Further, the present invention is a composite conductive layer composed of both a nanocarbon material and a carbon fiber having an average fiber diameter of 1 μm or more; A conductive sheet material for an electrode, comprising a first porous layer composed of carbon fibers and a nanocarbon layer located on the other surface of the composite conductive layer and composed of the nanocarbon material.
　（１１）また、本発明は、前記ナノカーボン層の両面のうち、前記複合導電層と反対側の面に位置し、前記カーボンファイバーで構成される第２多孔質層をさらに有する、（１０）に記載の電極用導電シート材料である。 (11) Further, the present invention further comprises a second porous layer which is located on a surface opposite to the composite conductive layer on both surfaces of the nanocarbon layer and which is composed of the carbon fiber. The conductive sheet material for an electrode according to 1.
　（１２）また、本発明は、レドックスフロー電池用電極の製造方法であって、第１多孔質層の片面に、ナノカーボン材料及びカーボンファイバーを含む複合分散液を塗布して乾燥させて、複合導電層を形成する工程と、前記複合導電層の両面のうち、前記第１多孔質層と反対側に位置する面に、前記ナノカーボン材料を含むナノカーボン分散液を塗布した後に乾燥させてナノカーボン層を形成する工程と、を有することを特徴とするレドックスフロー電池用電極の製造方法である。 (12) Further, the present invention is a method for producing an electrode for a redox flow battery, wherein a composite dispersion liquid containing a nanocarbon material and carbon fibers is applied to one surface of the first porous layer and dried to form a composite. And a step of forming a conductive layer, and applying a nanocarbon dispersion liquid containing the nanocarbon material to a surface of the composite conductive layer opposite to the first porous layer on both surfaces of the composite conductive layer, followed by drying to form a nanoparticle. And a step of forming a carbon layer, which is a method for manufacturing an electrode for a redox flow battery.
　本発明によれば、レドックスフロー電池のセル抵抗率の低減に寄与することができ、且つ機械的強度が十分高いレドックスフロー電池用の電極及びその製造方法を得ることができる。 According to the present invention, it is possible to obtain an electrode for a redox flow battery, which can contribute to reduction of the cell resistivity of the redox flow battery and has sufficiently high mechanical strength, and a manufacturing method thereof.
本実施形態に係るレドックスフロー電池用電極の一例を線図的に示す断面図である。It is a sectional view showing diagrammatically an example of an electrode for redox flow batteries concerning this embodiment. 本実施形態に係るレドックスフロー電池用電極を備えたレドックスフロー電池システムの構成の一例を示す構成図である。It is a block diagram which shows an example of a structure of the redox flow battery system provided with the electrode for redox flow batteries which concerns on this embodiment. 本実施形態に係るレドックスフロー電池用電極の製造方法における主要な工程の一例を説明するための図である。It is a figure for demonstrating an example of the main processes in the manufacturing method of the electrode for redox flow batteries which concerns on this embodiment.
　以下、本発明の具体的な実施形態について、図面を参照しながら詳細に説明する。なお、本発明は、以下の実施形態に限定されるものではなく、本発明の要旨を変更しない範囲で種々の変更が可能である。 Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and various modifications can be made without changing the gist of the present invention.
＜レドックスフロー電池用電極＞
　図１は、本実施形態に係るレドックスフロー電池用電極（以下、単に「電極」という場合がある。）の一例を示す断面図である。本実施形態に係るレドックスフロー電池用電極１は、複合導電層１１と、複合導電層１１の両面のうち、一方の面に位置する第１多孔質層１２と、複合導電層１１の他方の面に位置するナノカーボン層１３とを主構成とする。また、電極１は、ナノカーボン層１３の両面のうち、複合導電層１１と反対側の面に位置する第２多孔質層１５を、さらに有することが好ましい。すなわち、本実施形態に係るレドックスフロー電池用電極１は、その好ましい態様において、第２多孔質層１５の一方の面に、ナノカーボン層１３、複合導電層１１、第１多孔質層１２が順に積層されており、第１多孔質層１２は、後述するイオン交換膜６０に対向するように設けられる。また、第２多孔質層１５は、その他方の面が、後述する極板１６に隣接又は対向するように設けられる。 <Redox flow battery electrode>
FIG. 1 is a cross-sectional view showing an example of a redox flow battery electrode (hereinafter, may be simply referred to as “electrode”) according to the present embodiment. The redox flow battery electrode 1 according to the present embodiment includes a composite conductive layer 11, a first porous layer 12 located on one surface of both surfaces of the composite conductive layer 11, and the other surface of the composite conductive layer 11. And the nanocarbon layer 13 located in the main structure. Further, it is preferable that the electrode 1 further has a second porous layer 15 located on the surface opposite to the composite conductive layer 11 on both surfaces of the nanocarbon layer 13. That is, in the redox flow battery electrode 1 according to the present embodiment, in a preferable aspect thereof, the nanocarbon layer 13, the composite conductive layer 11, and the first porous layer 12 are sequentially provided on one surface of the second porous layer 15. The first porous layer 12 is laminated so as to face the ion exchange membrane 60 described later. The second porous layer 15 is provided such that the other surface thereof is adjacent to or opposite to the electrode plate 16 described later.
　本実施形態に係るレドックスフロー電池用電極１は、複合導電層１１と、第１多孔質層１２と、ナノカーボン層１３との少なくとも３層からなる積層構造とすることにより、電極１の機械的強度が高まるため、電極１の全体の厚さを薄くすることができ、それに伴って、レドックスフロー電池のセル抵抗率を低くすることができる。 The redox flow battery electrode 1 according to the present embodiment has a laminated structure including at least three layers of the composite conductive layer 11, the first porous layer 12, and the nanocarbon layer 13, so that the mechanical structure of the electrode 1 is improved. Since the strength is increased, the overall thickness of the electrode 1 can be reduced, and the cell resistivity of the redox flow battery can be reduced accordingly.
　また、本実施形態に係るレドックスフロー電池用電極１では、電極の積層構造を作製する際に、微細なナノカーボン材料を含む複合導電層１１及びナノカーボン層１３を、第１多孔質層１２の片面に順に塗布する等の手段によって積層することが可能になるため、ナノカーボン層１３、複合導電層１１及び第１多孔質層１２を、一体となるように形成することが可能になる。したがって、ナノカーボン材料を含む層、特にナノカーボン材料の濃度が高いナノカーボン層１３を設けても、第１多孔質層１２が十分な機械的強度を有することで、これらの層で構成される電極１も全体として十分な機械的強度を有することになるため、電極１の破損を起こり難くすることができるとともに、電極１をより容易に作製することができる。すなわち、ナノカーボン材料の濃度が高いナノカーボン層１３自体は、機械的強度が十分でなく破損しやすい性質を有するが、複合導電層１１や第１多孔質層１２とともに積層して一体となるように形成することで、ナノカーボン層１３が少なくとも第１多孔質層１２によって補強されるため、機械的強度を高めて破損し難くすることができる。 In addition, in the redox flow battery electrode 1 according to the present embodiment, the composite conductive layer 11 and the nanocarbon layer 13 containing the fine nanocarbon material are provided in the first porous layer 12 when the electrode laminated structure is produced. Since the layers can be laminated by a method such as sequentially coating on one side, the nanocarbon layer 13, the composite conductive layer 11, and the first porous layer 12 can be formed integrally. Therefore, even if the layer containing the nanocarbon material, particularly the nanocarbon layer 13 having a high concentration of the nanocarbon material, is provided, the first porous layer 12 has sufficient mechanical strength, and thus is formed of these layers. Since the electrode 1 also has sufficient mechanical strength as a whole, the electrode 1 can be less likely to be damaged and the electrode 1 can be manufactured more easily. That is, although the nanocarbon layer 13 itself having a high concentration of the nanocarbon material has a property that mechanical strength is not sufficient and is easily damaged, it may be laminated and integrated with the composite conductive layer 11 and the first porous layer 12. Since the nanocarbon layer 13 is reinforced by at least the first porous layer 12 by being formed, it is possible to increase mechanical strength and prevent damage.
　また、本実施形態に係るレドックスフロー電池用電極１では、ナノカーボン材料のみで構成されるナノカーボン層１３と、ナノカーボン材料及びカーボンファイバーの双方で構成される複合導電層１１とを一体化した積層構造として構成することによって、ナノカーボン層１３に含まれるナノカーボン材料が、複合導電層１１のカーボンファイバーに絡まって保持され易くなることで、ナノカーボン層１３からのナノカーボン材料の流出（分離）が有効に抑えられるため、電極の劣化を防ぐことができる。 In addition, in the redox flow battery electrode 1 according to the present embodiment, the nanocarbon layer 13 composed only of the nanocarbon material and the composite conductive layer 11 composed of both the nanocarbon material and the carbon fiber are integrated. By configuring as a laminated structure, the nanocarbon material contained in the nanocarbon layer 13 is easily entangled and retained by the carbon fibers of the composite conductive layer 11, so that the nanocarbon material flows out (separates) from the nanocarbon layer 13. ) Is effectively suppressed, it is possible to prevent the deterioration of the electrode.
　以下、複合導電層１１、第１多孔質層１２、ナノカーボン層１３及び第２多孔質層１５について、それぞれ詳細に説明する。 The composite conductive layer 11, the first porous layer 12, the nanocarbon layer 13, and the second porous layer 15 will be described in detail below.
　（複合導電層）
　複合導電層１１は、ナノカーボン材料及び平均繊維径が１μｍ以上のカーボンファイバーの双方を含んで構成される。これにより、表面積の相対的に大きなナノカーボン材料によって反応性が高められる一方で、ナノカーボン材料がカーボンファイバーによって保持されるため、電極１の外部へのナノカーボン材料の流出を抑えることができる。 (Composite conductive layer)
The composite conductive layer 11 is configured to include both a nanocarbon material and carbon fibers having an average fiber diameter of 1 μm or more. As a result, the reactivity is enhanced by the nanocarbon material having a relatively large surface area, while the nanocarbon material is held by the carbon fibers, so that the nanocarbon material can be prevented from flowing out of the electrode 1.
　このうち、ナノカーボン材料としては、三つの次元のうち少なくとも一つの次元についての大きさが１μｍ未満である炭素材料を含むことができ、その中でも、耐酸性及び耐酸化性の観点から、平均繊維径１μｍ未満のカーボンナノチューブを含むことが好ましい。ここで、ナノカーボン材料としては、カーボンナノチューブのほか、例えばカーボンナノファイバー、グラフェン等を挙げることができる。 Among them, the nanocarbon material may include a carbon material having a size of less than 1 μm in at least one of the three dimensions, and among them, from the viewpoint of acid resistance and oxidation resistance, the average fiber It preferably contains carbon nanotubes having a diameter of less than 1 μm. Here, as the nanocarbon material, in addition to carbon nanotubes, for example, carbon nanofibers and graphene can be cited.
　ナノカーボン材料がカーボンナノチューブを含む場合、カーボンナノチューブの平均繊維径は、好ましくは１ｎｍ～３００ｎｍ、より好ましくは１０ｎｍ～２００ｎｍ、さらに好ましくは１５ｎｍ～１５０ｎｍである。また、カーボンナノチューブの平均繊維長は、好ましくは０．１μｍ～３０μｍ、より好ましくは０．５μｍ～２５μｍ、さらに好ましくは０．５μｍ～２０μｍである。このとき、平均繊維径や平均繊維長が異なる、複数の種類のカーボンナノチューブが混合していてもよい。 When the nanocarbon material contains carbon nanotubes, the average fiber diameter of the carbon nanotubes is preferably 1 nm to 300 nm, more preferably 10 nm to 200 nm, and further preferably 15 nm to 150 nm. The average fiber length of the carbon nanotubes is preferably 0.1 μm to 30 μm, more preferably 0.5 μm to 25 μm, still more preferably 0.5 μm to 20 μm. At this time, a plurality of types of carbon nanotubes having different average fiber diameters or average fiber lengths may be mixed.
　また、複合導電層１１に含まれるカーボンファイバーは、１μｍ以上の大きい平均繊維径を有する。平均繊維径が１μｍ以上のカーボンファイバーを用いることで、より大きな空隙を複合導電層１１の内部に形成することができ、電解液を電極に通液させた時の圧力損失を小さくすることができる。また、複合導電層１１の導電性や機械的強度を向上する効果も期待できる。他方で、平均繊維径が２００μｍ以下のカーボンファイバーを用いることで、ナノカーボン材料がカーボンファイバーに絡まって保持され易くなるため、複合導電層１１や隣接するナノカーボン層１３に含まれるナノカーボン材料の、電解液への流出を抑えることができる。カーボンファイバーの平均繊維径は、好ましくは１μｍ～２００μｍ、より好ましくは２μｍ～１００μｍ、さらに好ましくは５μｍ～３０μｍである。また、カーボンファイバーの平均繊維長は、好ましくは０．０１ｍｍ～２０ｍｍ、より好ましくは０．０５ｍｍ～１０ｍｍ、さらに好ましくは０．１ｍｍ～８ｍｍである。 Also, the carbon fibers contained in the composite conductive layer 11 have a large average fiber diameter of 1 μm or more. By using carbon fibers having an average fiber diameter of 1 μm or more, it is possible to form a larger void inside the composite conductive layer 11 and reduce the pressure loss when the electrolytic solution is passed through the electrodes. .. Further, the effect of improving the conductivity and mechanical strength of the composite conductive layer 11 can be expected. On the other hand, by using carbon fibers having an average fiber diameter of 200 μm or less, the nanocarbon material is easily entangled and retained in the carbon fibers, so that the nanocarbon materials included in the composite conductive layer 11 and the adjacent nanocarbon layer 13 are The outflow to the electrolyte can be suppressed. The average fiber diameter of the carbon fibers is preferably 1 μm to 200 μm, more preferably 2 μm to 100 μm, still more preferably 5 μm to 30 μm. The average fiber length of the carbon fibers is preferably 0.01 mm to 20 mm, more preferably 0.05 mm to 10 mm, further preferably 0.1 mm to 8 mm.
　ここで、ナノカーボン材料であるカーボンナノチューブとカーボンファイバーの平均繊維径及び平均繊維長は、透過型電子顕微鏡（ＴＥＭ）を用いて、繊維（カーボンナノチューブ及びカーボンファイバー）の種類ごとに、無作為に１００本以上の繊維の直径を測定し、各々その算術平均値として求めることができる。 Here, the average fiber diameter and average fiber length of carbon nanotubes and carbon fibers, which are nanocarbon materials, are randomly determined for each type of fibers (carbon nanotubes and carbon fibers) using a transmission electron microscope (TEM). It is possible to measure the diameters of 100 or more fibers and obtain the arithmetic mean value of the measured values.
　複合導電層１１は、ナノカーボン材料とカーボンファイバーとで微細構造を構成する。この微細構造は、カーボンファイバーの表面にナノカーボン材料が付着した構造である。この構造によることで、ナノカーボン材料がカーボンファイバーに絡まって保持されるため、複合導電層１１や隣接するナノカーボン層１３に含まれるナノカーボン材料が、電解液に流出することを抑えることができる。また、複合導電層１１における導電性を高める観点から、ナノカーボン材料であるカーボンナノチューブは、複数のカーボンファイバー間に跨った構造を有してもよい。 The composite conductive layer 11 has a fine structure made of nanocarbon material and carbon fiber. This fine structure is a structure in which a nanocarbon material is attached to the surface of carbon fiber. With this structure, since the nanocarbon material is entangled and held in the carbon fiber, the nanocarbon material contained in the composite conductive layer 11 or the adjacent nanocarbon layer 13 can be suppressed from flowing out into the electrolytic solution. .. In addition, from the viewpoint of enhancing the conductivity of the composite conductive layer 11, the carbon nanotube, which is a nanocarbon material, may have a structure that spans a plurality of carbon fibers.
　複合導電層１１は、ナノカーボン材料とカーボンファイバーの合計１００質量部に対する、カーボンファイバーの含有量が、好ましくは９０質量部以下、より好ましくは８０質量部以下、さらに好ましくは７０質量部以下である。また、ナノカーボン材料とカーボンファイバーの合計１００質量部に対する、前記カーボンファイバーの含有量の下限は、好ましくは２０質量部以上、より好ましくは３０質量部以上、さらに好ましくは４０質量部以上である。複合導電層１１におけるカーボンファイバーの含有量をこの範囲内にすることで、複合導電層１１における反応性を向上しつつ、電解液を電極に通液させた時の圧力損失を小さくすることができる。 The composite conductive layer 11 has a carbon fiber content of preferably 90 parts by mass or less, more preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less based on 100 parts by mass of the total of the nanocarbon material and the carbon fiber. .. Further, the lower limit of the content of the carbon fiber is preferably 20 parts by mass or more, more preferably 30 parts by mass or more, and further preferably 40 parts by mass or more based on 100 parts by mass of the total of the nanocarbon material and the carbon fiber. By setting the content of the carbon fibers in the composite conductive layer 11 within this range, it is possible to improve the reactivity in the composite conductive layer 11 and reduce the pressure loss when the electrolytic solution is passed through the electrodes. ..
　複合導電層１１の乾燥状態での厚み（厚さ寸法）は、好ましくは０．０１ｍｍ～０．２０ｍｍ、より好ましくは０．０１ｍｍ～０．１５ｍｍ、さらに好ましくは０．０２ｍｍ～０．１５ｍｍ、さらに好ましくは０．０２ｍｍ～０．１０ｍｍである。複合導電層１１の厚みを０．０１ｍｍ以上にすることで、複合導電層１１における反応性が高められることで、レドックスフロー電池の充放電効率を高めることができる。また、電極１の積層構造を構成する層として、厚みが０．０１ｍｍ以上の複合導電層１１をナノカーボン層１３に一体化して設けることによって、ナノカーボン層１３に含まれるナノカーボン材料が、複合導電層１１のカーボンファイバーに絡まって保持されるため、ナノカーボン層１３を電極１に保持し易くすることができる。他方で、複合導電層１１の厚みを０．２０ｍｍ以下と薄くすることで、この電極をレドックスフロー電池に用いたときに、充放電によって生成したプロトンが速やかにイオン交換膜へ移動するため、セル抵抗率を低減することができる。 The thickness (thickness dimension) of the composite conductive layer 11 in a dry state is preferably 0.01 mm to 0.20 mm, more preferably 0.01 mm to 0.15 mm, further preferably 0.02 mm to 0.15 mm, and further It is preferably 0.02 mm to 0.10 mm. By setting the thickness of the composite conductive layer 11 to 0.01 mm or more, the reactivity in the composite conductive layer 11 is enhanced, and thus the charge/discharge efficiency of the redox flow battery can be enhanced. In addition, by providing the composite conductive layer 11 having a thickness of 0.01 mm or more integrally with the nanocarbon layer 13 as a layer constituting the laminated structure of the electrode 1, the nanocarbon material contained in the nanocarbon layer 13 is a composite material. Since it is entangled and held by the carbon fibers of the conductive layer 11, the nanocarbon layer 13 can be easily held by the electrode 1. On the other hand, by reducing the thickness of the composite conductive layer 11 to 0.20 mm or less, when this electrode is used in a redox flow battery, the protons generated by charge and discharge move quickly to the ion exchange membrane, and The resistivity can be reduced.
　（第１多孔質層）
　第１多孔質層１２は、複合導電層１１の両面のうち一方の面に設けられ、平均繊維径が１μｍ以上のカーボンファイバーによって構成される。第１多孔質層１２は、電解液を電極に通液させた時の圧力損失が小さい層であり、また、単独で容易に取り扱える程度の高い機械的強度を有する層である。 (First porous layer)
The first porous layer 12 is provided on one surface of both surfaces of the composite conductive layer 11, and is composed of carbon fibers having an average fiber diameter of 1 μm or more. The first porous layer 12 is a layer having a small pressure loss when the electrolytic solution is passed through the electrode, and has a high mechanical strength that can be easily handled alone.
　第１多孔質層１２に含まれるカーボンファイバーは、複合導電層１１に含まれるものと同様に、１μｍ以上の大きい平均繊維径を有する。これにより、第１多孔質層１２の内部に、より大きな空隙を形成することができるため、電解液を電極に通液させた時の圧力損失を小さくすることができる。第１多孔質層１２に含まれるカーボンファイバーの平均繊維径は、好ましくは１μｍ～２００μｍ、より好ましくは２μｍ～１００μｍ、さらに好ましくは５μｍ～３０μｍである。 The carbon fiber contained in the first porous layer 12 has a large average fiber diameter of 1 μm or more, similar to that contained in the composite conductive layer 11. Thereby, a larger void can be formed inside the first porous layer 12, so that the pressure loss when the electrolytic solution is passed through the electrode can be reduced. The average fiber diameter of the carbon fibers contained in the first porous layer 12 is preferably 1 μm to 200 μm, more preferably 2 μm to 100 μm, still more preferably 5 μm to 30 μm.
　また、第１多孔質層１２を構成するカーボンファイバーは、比較的長い繊維を織った織物、繊維を織らずに絡み合わせた不織布（フェルト）、比較的短い繊維を漉いてシート状にしたペーパーのうち、何れの形態であってもよい。このとき、カーボンファイバーの平均繊維長として、それぞれの形態において通常用いられる長さが採用されることが好ましい。 The carbon fibers forming the first porous layer 12 include a woven fabric of relatively long fibers, a non-woven fabric (felt) woven without woven fibers, and a sheet of paper made by filtering relatively short fibers. Of these, any form may be used. At this time, as the average fiber length of the carbon fibers, it is preferable to adopt a length usually used in each form.
　第１多孔質層１２の乾燥状態での厚み（厚さ寸法）は、好ましくは０．０５ｍｍ～０．３０ｍｍ、より好ましくは０．０７ｍｍ～０．２５ｍｍ、さらに好ましくは０．１０ｍｍ～０．２０ｍｍである。第１多孔質層１２の厚みを上記範囲にすることで、レドックスフロー電池用電極の機械的強度を十分に保つとともに、レドックスフロー電池に用いたときのセル抵抗率の上昇を抑制することができる。 The thickness (thickness dimension) of the first porous layer 12 in a dry state is preferably 0.05 mm to 0.30 mm, more preferably 0.07 mm to 0.25 mm, further preferably 0.10 mm to 0.20 mm. Is. By setting the thickness of the first porous layer 12 in the above range, it is possible to sufficiently maintain the mechanical strength of the electrode for a redox flow battery and to suppress an increase in cell resistivity when used in a redox flow battery. ..
　なお、複合導電層１１と第１多孔質層１２は、明確な境界によって区別されなくてもよく、複合導電層１１と第１多孔質層１２とが一体化されていてもよい。複合導電層１１と第１多孔質層１２が一体化された層は、厚さ方向について一方の側にナノカーボン材料を含まない領域を有し、且つ、他方の側にナノカーボン材料を含む領域を有するように構成されてもよい。このとき、ナノカーボン材料を含む領域が複合導電層１１に相当し、ナノカーボン材料を含まない領域が第１多孔質層１２に相当する。複合導電層１１と第１多孔質層１２とが接触する部分では、複合導電層１１に含まれていたナノカーボン材料の一部が第１多孔質層１２に入り込むため、これらの境界が不明確になって一体化することがある。その場合であっても、一体化された複合導電層１１と第１多孔質層１２によって、レドックスフロー電池用電極１の機械的強度を高めることができる。 The composite conductive layer 11 and the first porous layer 12 may not be distinguished by a clear boundary, and the composite conductive layer 11 and the first porous layer 12 may be integrated. The layer in which the composite conductive layer 11 and the first porous layer 12 are integrated has a region containing no nanocarbon material on one side in the thickness direction and a region containing nanocarbon material on the other side. May be configured to have. At this time, the region containing the nanocarbon material corresponds to the composite conductive layer 11, and the region not containing the nanocarbon material corresponds to the first porous layer 12. In the portion where the composite conductive layer 11 and the first porous layer 12 are in contact with each other, a part of the nanocarbon material contained in the composite conductive layer 11 enters the first porous layer 12, so that the boundary between them is unclear. May be integrated into one. Even in that case, the mechanical strength of the redox flow battery electrode 1 can be increased by the integrated composite conductive layer 11 and the first porous layer 12.
　（ナノカーボン層）
　ナノカーボン層１３は、複合導電層１１の両面のうち、第１多孔質層１２と反対側の面に設けられ、ナノカーボン材料によって構成される。ナノカーボン層１３は、ナノサイズを有するナノカーボン材料の集合体であることから、他の層と比べて、単位体積当たりの表面積が大きく、活性点も多いため、電極反応が盛んに行われる層である。他方で、ナノカーボン層１３は、機械的強度が他の層と比べて劣るため、本実施形態では、ナノカーボン層１３を、複合導電層１１及びカーボンファイバーで構成されている第１多孔質層１２との一体積層構造で構成する。これにより、ナノカーボン層１３の強度不足は、機械的強度の高い複合導電層１１及び第１多孔質層１２との一体化によって、十分に補うことができる。 (Nanocarbon layer)
The nanocarbon layer 13 is provided on the surface of the composite conductive layer 11 opposite to the first porous layer 12, and is made of a nanocarbon material. Since the nanocarbon layer 13 is an aggregate of nanocarbon materials having a nano size, it has a large surface area per unit volume and a large number of active points, as compared with other layers, and thus a layer where electrode reaction is actively performed. Is. On the other hand, since the nanocarbon layer 13 is inferior in mechanical strength to the other layers, in the present embodiment, the nanocarbon layer 13 is composed of the composite conductive layer 11 and the carbon fiber as the first porous layer. 12 and an integral laminated structure. Thereby, the insufficient strength of the nanocarbon layer 13 can be sufficiently compensated by the integration of the composite conductive layer 11 and the first porous layer 12 having high mechanical strength.
　ナノカーボン層１３を構成するナノカーボン材料としては、複合導電層１１と同様に、三つの次元のうち少なくとも一つの次元についての大きさが１μｍ未満である炭素材料を含むことができる。その中でも、耐酸性及び耐酸化性の観点から、平均繊維径１μｍ未満のカーボンナノチューブを含むことが好ましい。 As with the composite conductive layer 11, the nanocarbon material forming the nanocarbon layer 13 may include a carbon material having a size of less than 1 μm in at least one of the three dimensions. Among them, from the viewpoint of acid resistance and oxidation resistance, it is preferable to include carbon nanotubes having an average fiber diameter of less than 1 μm.
　ナノカーボン材料としてカーボンナノチューブを含む場合、カーボンナノチューブの平均繊維径及び平均繊維長も、複合導電層１１に含まれるものと同様にすることができる。このとき、平均繊維径や平均繊維長が異なる、複数の種類のカーボンナノチューブが混合していてもよい。 When carbon nanotubes are included as the nanocarbon material, the average fiber diameter and average fiber length of the carbon nanotubes can be the same as those included in the composite conductive layer 11. At this time, a plurality of types of carbon nanotubes having different average fiber diameters or average fiber lengths may be mixed.
　ナノカーボン層１３の乾燥状態での厚み（厚さ寸法）は、好ましくは０．０１ｍｍ～０．２０ｍｍ、より好ましくは０．０１ｍｍ～０．１５ｍｍ、さらに好ましくは０．０１ｍｍ～０．１０ｍｍである。ナノカーボン層１３の厚みを０．０１ｍｍ以上にすることで、ナノカーボン層１３における反応性が高められるため、レドックスフロー電池の充放電効率を高めることができる。他方で、この厚みを０．２０ｍｍ以下にすることで、ナノカーボン層１３への電解液の通液性を高めることができる。 The dry thickness (thickness dimension) of the nanocarbon layer 13 is preferably 0.01 mm to 0.20 mm, more preferably 0.01 mm to 0.15 mm, and further preferably 0.01 mm to 0.10 mm. .. By setting the thickness of the nanocarbon layer 13 to 0.01 mm or more, the reactivity of the nanocarbon layer 13 is enhanced, and thus the charge/discharge efficiency of the redox flow battery can be enhanced. On the other hand, if the thickness is 0.20 mm or less, the liquid permeability of the electrolytic solution to the nanocarbon layer 13 can be improved.
　本実施形態に係るレドックスフロー電池用電極１では、第１多孔質層１２の厚さ寸法（ｂ）に対する複合導電層１１の厚さ寸法（ａ）の比率（ａ／ｂ）は、好ましくは０．１０～２．０、より好ましくは０．２０～１．５の範囲、さらに好ましくは０．２０～１．０の範囲である。また、第１多孔質層１２の厚さ寸法（ｂ）に対するナノカーボン層１３の厚さ寸法（ｃ）の比率（ｃ／ｂ）は、好ましくは０．０５～２．０、より好ましくは０．０５～１．０、さらに好ましくは０．２～１．０の範囲である。比率（ａ／ｂ）や比率（ｃ／ｂ）が上記の範囲内であれば、所望の低い抵抗率と、高い機械的強度を有する電極１を得易くすることができ、且つ電極１において良好な通液性を確保することができる。 In the electrode 1 for redox flow battery according to this embodiment, the ratio (a/b) of the thickness dimension (a) of the composite conductive layer 11 to the thickness dimension (b) of the first porous layer 12 is preferably 0. 10 to 2.0, more preferably 0.20 to 1.5, still more preferably 0.20 to 1.0. The ratio (c/b) of the thickness dimension (c) of the nanocarbon layer 13 to the thickness dimension (b) of the first porous layer 12 is preferably 0.05 to 2.0, more preferably 0. The range is 0.05 to 1.0, and more preferably 0.2 to 1.0. When the ratio (a/b) or the ratio (c/b) is within the above range, it is possible to easily obtain the electrode 1 having a desired low resistivity and high mechanical strength, and the electrode 1 is good. It is possible to secure a sufficient liquid permeability.
　なお、ナノカーボン層１３と複合導電層１１は、明確な境界によって区別されなくてもよく、ナノカーボン層１３と複合導電層１１とが一体化されていてもよい。ナノカーボン層１３と複合導電層１１が一体化された層は、厚さ方向について一方の側の少なくとも一部分に、ナノカーボン材料からなる領域を有するように構成されることが好ましい。このとき、ナノカーボン材料からなる領域が、一定の厚みを持った層を有するように構成されることがより好ましい。ここで、ナノカーボン層１３と複合導電層１１とが接触する部分では、ナノカーボン層１３に含まれていたナノカーボン材料の一部が複合導電層１１に入り込むため、これらの境界が不明確になって一体化することがある。その場合であっても、一体化されたナノカーボン層１３と複合導電層１１が、第１多孔質層１２によって支持されるため、レドックスフロー電池用電極１の機械的強度を高めることができる。 Note that the nanocarbon layer 13 and the composite conductive layer 11 may not be distinguished by a clear boundary, and the nanocarbon layer 13 and the composite conductive layer 11 may be integrated. It is preferable that the layer in which the nanocarbon layer 13 and the composite conductive layer 11 are integrated has a region made of a nanocarbon material in at least a part of one side in the thickness direction. At this time, it is more preferable that the region made of the nanocarbon material has a layer having a constant thickness. Here, since a part of the nanocarbon material contained in the nanocarbon layer 13 enters the composite conductive layer 11 at the portion where the nanocarbon layer 13 and the composite conductive layer 11 are in contact with each other, the boundary between them is unclear. May become integrated. Even in that case, since the integrated nanocarbon layer 13 and the composite conductive layer 11 are supported by the first porous layer 12, the mechanical strength of the redox flow battery electrode 1 can be increased.
　（第２多孔質層）
　第２多孔質層１５は、ナノカーボン層１３の両面のうち、複合導電層１１と反対側の面に位置し、平均繊維径が１μｍ以上のカーボンファイバーによって構成される層であり、必要に応じて設けることができる。第２多孔質層１５は、電解液を電極に通液させた際の圧力損失が小さい層であり、また、単独で容易に取り扱える程度の高い機械的強度を有する層である。本実施形態に係るレドックスフロー電池用電極１は、第２多孔質層１５を設けることで、第２多孔質層１５の内部で電解液が広がるため、第２多孔質層１５のうちナノカーボン層１３と隣接する面のほぼ全面にわたって電解液を広げることができる。その結果、電解液が、ナノカーボン層１３の面に対してより均一且つより垂直的に流れるため、レドックスフロー電池用電極１における通液性をより高めることができる。 (Second porous layer)
The second porous layer 15 is a layer that is located on a surface opposite to the composite conductive layer 11 on both surfaces of the nanocarbon layer 13, and is composed of carbon fibers having an average fiber diameter of 1 μm or more. Can be provided. The second porous layer 15 is a layer having a small pressure loss when the electrolytic solution is passed through the electrode, and has a high mechanical strength that can be easily handled by itself. In the electrode 1 for a redox flow battery according to this embodiment, by providing the second porous layer 15, the electrolytic solution spreads inside the second porous layer 15, so that the nanocarbon layer of the second porous layer 15 is included. The electrolytic solution can be spread over almost the entire surface adjacent to 13. As a result, the electrolytic solution flows more uniformly and vertically to the surface of the nanocarbon layer 13, so that the liquid permeability in the redox flow battery electrode 1 can be further enhanced.
　第２多孔質層１５に含まれるカーボンファイバーとしては、第１多孔質層１２に含まれるものと同様のものを用いることができる。 As the carbon fiber contained in the second porous layer 15, the same carbon fiber contained in the first porous layer 12 can be used.
　第２多孔質層１５の乾燥状態での厚み（厚さ寸法）は、好ましくは０．１０ｍｍ～０．５０ｍｍ、より好ましくは０．１５ｍｍ～０．４０ｍｍ、さらに好ましくは０．２０ｍｍ～０．４０ｍｍである。第２多孔質層１５の厚みを０．１０ｍｍ～０．５０ｍｍの範囲にすることにより、電解液が第２多孔質層１５の内部で均一に広がるため、電極１の通液性を向上することができる。 The thickness (thickness dimension) of the second porous layer 15 in a dry state is preferably 0.10 mm to 0.50 mm, more preferably 0.15 mm to 0.40 mm, further preferably 0.20 mm to 0.40 mm. Is. By setting the thickness of the second porous layer 15 within the range of 0.10 mm to 0.50 mm, the electrolytic solution spreads uniformly inside the second porous layer 15, so that the liquid permeability of the electrode 1 is improved. You can
＜レドックスフロー電池＞
　図２は、本実施形態に係るレドックスフロー電池の構成の一例を示す概略構成図であり、バナジウム化合物を活物質として用いた場合を例として示すものである。本実施形態に係るレドックスフロー電池２は、電池セル６を最小単位として、これを単独、又は複数枚積層した電池セルスタックと称される形態で使用され、電池セル６に電解液を循環させて充放電を行なう。 <Redox flow battery>
FIG. 2 is a schematic configuration diagram showing an example of the configuration of the redox flow battery according to the present embodiment, and shows an example in which a vanadium compound is used as an active material. The redox flow battery 2 according to the present embodiment is used in a form called a battery cell stack in which the battery cell 6 is used as a minimum unit, or a single unit of the battery cell 6 is stacked, and an electrolytic solution is circulated in the battery cell 6. Charge and discharge.
　本実施形態に係るレドックスフロー電池２は、正極電極１ａを内蔵する正極セル４１と、負極電極１ｂを内蔵する負極セル５１と、正極電極１ａ及び負極電極１ｂの間に介在されて両セルを分離するとともに、所定のイオンを透過するイオン交換膜６０とを有する電池セル６を主構成とする。 The redox flow battery 2 according to the present embodiment includes a positive electrode cell 41 having a positive electrode 1a incorporated therein, a negative electrode cell 51 having a negative electrode 1b incorporated therein, and a positive electrode 1a and a negative electrode 1b interposed therebetween to separate the cells. In addition, the battery cell 6 having the ion exchange membrane 60 that allows predetermined ions to permeate is the main component.
　本実施形態に係るレドックスフロー電池２は、正極電極１ａ及び負極電極１ｂの一方又は両方に、上述のレドックスフロー電池用電極１を用いる。ここで、レドックスフロー電池用電極１を正極電極１ａとして用いる場合、レドックスフロー電池用電極１は、イオン交換膜６０と極板１６ａとの間に配置される。また、レドックスフロー電池用電極１を負極電極１ｂとして用いる場合、レドックスフロー電池用電極１は、イオン交換膜６０と極板１６ｂとの間に配置される。このとき、レドックスフロー電池用電極１は、第１多孔質層１２の両面のうち、複合導電層１１と反対側の面がイオン交換膜６０と対向するように設けられることが好ましい。このとき、レドックスフロー電池用電極１は、第２多孔質層１５の両面のうち、ナノカーボン層１３と反対側の面が極板１６ａ、１６ｂと対向することになる。 The redox flow battery 2 according to the present embodiment uses the above-mentioned redox flow battery electrode 1 for one or both of the positive electrode 1a and the negative electrode 1b. Here, when the redox flow battery electrode 1 is used as the positive electrode 1a, the redox flow battery electrode 1 is disposed between the ion exchange membrane 60 and the electrode plate 16a. When the redox flow battery electrode 1 is used as the negative electrode 1b, the redox flow battery electrode 1 is disposed between the ion exchange membrane 60 and the electrode plate 16b. At this time, it is preferable that the electrode 1 for redox flow battery is provided so that the surface of the first porous layer 12 opposite to the composite conductive layer 11 faces the ion exchange membrane 60. At this time, in the redox flow battery electrode 1, the surface of the second porous layer 15 opposite to the nanocarbon layer 13 faces the electrode plates 16a and 16b.
　なお、本実施形態に係るレドックスフロー電池２は、電極１（正極電極１ａ又は負極電極１ｂ）が、第２多孔質層１５の一方の面が極板１６ａ、１６ｂと対向するように設けられる態様に限られない。例えば、第１多孔質層１２の両面のうち、複合導電層１１と反対側の面が、極板１６ａ、１６ｂと対向するように設けられていてもよい。このとき、レドックスフロー電池用電極の第２多孔質層１５の両面のうち、ナノカーボン層と反対側の面が、イオン交換膜６０と対向することになる。 In the redox flow battery 2 according to this embodiment, the electrode 1 (the positive electrode 1a or the negative electrode 1b) is provided such that one surface of the second porous layer 15 faces the electrode plates 16a and 16b. Not limited to For example, of the both surfaces of the first porous layer 12, the surface opposite to the composite conductive layer 11 may be provided so as to face the electrode plates 16a and 16b. At this time, of the two surfaces of the second porous layer 15 of the electrode for redox flow battery, the surface opposite to the nanocarbon layer faces the ion exchange membrane 60.
　本実施形態では、上述のレドックスフロー電池用電極１を、正極電極１ａ及び負極電極１ｂの一方又は両方に用いることで、レドックスフロー電池２における電解液の充放電効率を高め、且つレドックスフロー電池２のセル抵抗率を低くすることができる。また、レドックスフロー電池用電極１を構成する積層構造（体）の一部の層又は積層構造全体の破損を起こり難くすることができる。 In the present embodiment, by using the electrode 1 for a redox flow battery described above as one or both of the positive electrode 1a and the negative electrode 1b, the charge/discharge efficiency of the electrolytic solution in the redox flow battery 2 is increased, and the redox flow battery 2 is used. The cell resistivity of can be lowered. In addition, it is possible to make it difficult for some layers of the laminated structure (body) constituting the redox flow battery electrode 1 or the entire laminated structure to be damaged.
　レドックスフロー電池２の正極側及び負極側の電解液に含まれる活物質としては、例えば、バナジウム化合物、モリブデン化合物、スズ化合物、鉄化合物、クロム化合物、マンガン化合物、チタン化合物、亜鉛化合物のうち１種又は２種以上が挙げられる。特に、バナジウム化合物を活物質として正極側及び負極側の両方の電解液に含むことが好ましく、また、マンガン化合物を活物質として正極側の電解液に含み、且つチタン化合物を活物質として負極側の電解液に含むことも好ましい。 The active material contained in the electrolytic solution on the positive electrode side and the negative electrode side of the redox flow battery 2 is, for example, one of a vanadium compound, a molybdenum compound, a tin compound, an iron compound, a chromium compound, a manganese compound, a titanium compound, and a zinc compound. Alternatively, two or more kinds may be mentioned. In particular, it is preferable to include a vanadium compound as an active material in both the positive electrode side and negative electrode side electrolytic solutions, and also include a manganese compound in the positive electrode side electrolytic solution as an active material, and a titanium compound as an active material on the negative electrode side. It is also preferable to include it in the electrolytic solution.
　レドックスフロー電池２に用いられるイオン交換膜６０としては、公知の陽イオン交換膜を用いることができる。具体的には、スルホン酸基を有するパーフルオロカーボン重合体、スルホン酸基を有する炭化水素系高分子化合物、リン酸等の無機酸をドープさせた高分子化合物、一部がプロトン伝導性の官能基で置換された有機／無機ハイブリッドポリマー、高分子マトリックスにリン酸溶液や硫酸溶液を含浸させたプロトン伝導体が挙げられる。これらのうち、スルホン酸基を有するパーフルオロカーボン重合体が好ましく、ナフィオン（登録商標）がより好ましい。 As the ion exchange membrane 60 used in the redox flow battery 2, a known cation exchange membrane can be used. Specifically, a perfluorocarbon polymer having a sulfonic acid group, a hydrocarbon-based polymer compound having a sulfonic acid group, a polymer compound doped with an inorganic acid such as phosphoric acid, a part of which is a proton-conductive functional group. Examples of the organic/inorganic hybrid polymer substituted with, and a proton conductor obtained by impregnating a polymer matrix with a phosphoric acid solution or a sulfuric acid solution. Among these, perfluorocarbon polymers having a sulfonic acid group are preferable, and Nafion (registered trademark) is more preferable.
　レドックスフロー電池２に用いられる極板１６ａ、１６ｂとしても、公知のものを用いることができ、例えば炭素を含有する導電性材料を用いることができる。より具体的には、黒鉛と有機高分子化合物とからなる導電性樹脂、もしくは黒鉛の一部をカーボンブラック及びダイヤモンドライクカーボンのうち一方又は両方に置換した導電性樹脂、及びカーボンと樹脂とを混練成形した成形材が挙げられる。これらのうち、カーボンと樹脂とを混練成形した成形材を用いることが好ましい。 As the electrode plates 16a and 16b used in the redox flow battery 2, known ones can be used, and for example, a conductive material containing carbon can be used. More specifically, a conductive resin composed of graphite and an organic polymer compound, or a conductive resin in which a part of graphite is replaced with one or both of carbon black and diamond-like carbon, and carbon and the resin are kneaded. An example of the molded material is a molded material. Of these, it is preferable to use a molding material obtained by kneading and molding carbon and resin.
　ここで、極板１６ａ、１６ｂは、レドックスフロー電池用電極１の外部に通じた電解液の流路を備えてもよい。より具体的には、電解液の通液性を向上させるための溝や凹みからなる溝部が電極側に形成されていることが好ましい。極板１６ａ、１６ｂに形成される溝や凹みは、図１に示される溝部１６１のように１本のみ形成されていてもよく、レドックスフロー電池用電極１に対向する面に複数本形成されていてもよい。また、溝や凹みの大きさについても特に限定されない。さらに、極板１６ａ、１６ｂは、図示しない集電板を介して電気のやりとりを行ってもよい。 Here, the electrode plates 16a and 16b may be provided with a flow path of an electrolytic solution which communicates with the outside of the redox flow battery electrode 1. More specifically, it is preferable that a groove portion including a groove or a recess for improving the liquid permeability of the electrolytic solution is formed on the electrode side. Only one groove or recess may be formed in the electrode plates 16a and 16b as in the groove portion 161 shown in FIG. 1, and a plurality of grooves or recesses may be formed on the surface facing the redox flow battery electrode 1. May be. Further, the size of the groove or the dent is not particularly limited. Further, the electrode plates 16a and 16b may exchange electricity via a current collector plate (not shown).
　レドックスフロー電池２は、正極セル４１に循環供給する正極電解液を貯蔵する正極電解液タンク４２と、正極電解液を正極電解液タンク４２から正極セル４１に送る正極往路配管４３と、正極電解液を正極セル４１から正極電解液タンク４２に戻す正極復路配管４４とを備える。このうち、正極往路配管４３には、正極電解液を循環させるためのポンプ４５が配置される。 The redox flow battery 2 includes a positive electrode electrolytic solution tank 42 that stores a positive electrode electrolytic solution that is circulated and supplied to the positive electrode cell 41, a positive electrode forward pipe 43 that sends the positive electrode electrolytic solution from the positive electrode electrolytic solution tank 42 to the positive electrode cell 41, and a positive electrode electrolytic solution. And a positive electrode return pipe 44 for returning from the positive electrode cell 41 to the positive electrode electrolyte tank 42. Of these, a pump 45 for circulating the positive electrode electrolytic solution is arranged in the positive electrode outward piping 43.
　同様に、レドックスフロー電池２は、負極セル５１に循環供給する負極電解液を貯蔵する負極電解液タンク５２と、負極電解液を負極電解液タンク５２から負極セル５１に送る負極往路配管５３と、負極電解液を負極セル５１から負極電解液タンク５２に戻す負極復路配管５４とを備える。このうち、負極往路配管５３には、負極電解液を循環させるためのポンプ５５が配置される。 Similarly, the redox flow battery 2 includes a negative electrode electrolytic solution tank 52 that stores a negative electrode electrolytic solution that is circulated and supplied to the negative electrode cell 51, and a negative electrode outward piping 53 that sends the negative electrode electrolytic solution from the negative electrode electrolytic solution tank 52 to the negative electrode cell 51. And a negative electrode return pipe 54 for returning the negative electrode electrolytic solution from the negative electrode cell 51 to the negative electrode electrolytic solution tank 52. Of these, a pump 55 for circulating the negative electrode electrolytic solution is arranged in the negative electrode outward piping 53.
　上記構成のレドックスフロー電池２において、正極電解液タンク４２内の電解液は、ポンプ４５を作動させることにより、正極往路配管４３を通って電池セル６（より厳密には正極セル４１）に送られる。電池セル６に送られた正極電解液は、電池セル６の下方から内部を通って上方に排出され、且つ正極復路配管４４を通して正極電解液タンク４２に戻されることで、図中矢印Ａ方向に循環する。同様に、負極電解液タンク５２内の電解液は、ポンプ５５を作動させることにより、負極往路配管５３を通って電池セル６（より厳密には負極セル５１）に送られる。電池セル６に送られた電解液は、電池セル６の下方から内部を通って上方に排出され、且つ負極復路配管５４を通して負極電解液タンク５２に戻されることで、図中矢印Ｂ方向に循環する。 In the redox flow battery 2 having the above-described configuration, the electrolytic solution in the positive electrode electrolytic solution tank 42 is sent to the battery cell 6 (more strictly, the positive electrode cell 41) through the positive electrode outward piping 43 by operating the pump 45. .. The positive electrode electrolytic solution sent to the battery cell 6 is discharged upward through the inside of the battery cell 6 and returned to the positive electrode electrolytic solution tank 42 through the positive electrode return pipe 44, whereby the positive electrode electrolytic solution is directed in the direction of arrow A in the figure. Circulate. Similarly, the electrolytic solution in the negative electrode electrolytic solution tank 52 is sent to the battery cell 6 (more strictly, the negative electrode cell 51) through the negative electrode outward pipe 53 by operating the pump 55. The electrolytic solution sent to the battery cell 6 is circulated in the direction of arrow B in the figure by being discharged upward through the inside of the battery cell 6 and returned to the negative electrode electrolytic solution tank 52 through the negative electrode return pipe 54. To do.
　これにより、電池セル６の中で電解液に含まれる活物質の酸化還元反応が行われるため、電力を取出し又は貯蔵することが可能となる。すなわち、交流／直流変換器９を介して発電所等の交流電源８１からの電力を充電し、充電した電力を、交流／直流変換器９を介して負荷電源８２に放電することが可能となる。 Due to this, since the redox reaction of the active material contained in the electrolytic solution is performed in the battery cell 6, it becomes possible to extract or store electric power. That is, it becomes possible to charge the electric power from the AC power supply 81 such as a power plant via the AC/DC converter 9 and discharge the charged power to the load power supply 82 via the AC/DC converter 9. ..
　本実施形態では、レドックスフロー電池２の電池セル６を、単セルで構成した場合で説明したが、複数の単セルを積層したセルスタックと呼ばれる形態で構成してもよい（図示せず）。このとき、積層されたセルスタックにおいて隣接する電池セル６の極板１６ａ、１６ｂは、１枚の双極板により形成し、その両面のそれぞれに、電極１の積層構造を設けてもよい。 In the present embodiment, the battery cell 6 of the redox flow battery 2 has been described as a single cell, but it may be configured in a form called a cell stack in which a plurality of single cells are stacked (not shown). At this time, the polar plates 16a and 16b of the adjacent battery cells 6 in the stacked cell stacks may be formed by one bipolar plate, and the stacked structure of the electrode 1 may be provided on each of both surfaces thereof.
＜電極用導電シート材料＞
　本実施形態に係る電極用導電シート材料は、電極、特に上述したレドックスフロー電池用電極１に用いられる導電シート材料である。この導電シート材料は、ナノカーボン材料及びカーボンファイバーの双方で構成される複合導電層１１と、複合導電層１１の両面のうち一方の面に位置し、カーボンファイバーで構成される第１多孔質層１２と、複合導電層の他方の面に位置し、ナノカーボン材料で構成されたナノカーボン層１３とを少なくとも有する。 <Conductive sheet material for electrodes>
The conductive sheet material for electrodes according to the present embodiment is a conductive sheet material used for electrodes, particularly for the above-described redox flow battery electrode 1. This conductive sheet material is a composite conductive layer 11 composed of both a nanocarbon material and carbon fibers, and a first porous layer composed of carbon fibers and located on one surface of both surfaces of the composite conductive layer 11. 12 and a nanocarbon layer 13 located on the other surface of the composite conductive layer and made of a nanocarbon material.
　電極用導電シート材料を上記の層構成にすることで、複合導電層の一方の面に第１多孔質層が配置され、他方の面にナノカーボン層が配置された構造を得ることができる。それとともに、第１多孔質層によって積層構造の作製に耐えうる機械的強度が確保されるため、電極用導電シート材料の破損が起こり難くなって電極の作製が容易になる。そのため、レドックスフロー電池のセル抵抗率の低減に寄与することができ、且つ機械的強度の高い電極を、より容易に得ることができる。 By forming the conductive sheet material for electrodes into the above layer structure, it is possible to obtain a structure in which the first porous layer is arranged on one surface of the composite conductive layer and the nanocarbon layer is arranged on the other surface. At the same time, the first porous layer ensures the mechanical strength that can withstand the production of the laminated structure, so that the conductive sheet material for electrodes is less likely to be damaged and the production of electrodes is facilitated. Therefore, it is possible to contribute to the reduction of the cell resistivity of the redox flow battery, and it is possible to more easily obtain an electrode having high mechanical strength.
＜レドックスフロー電池用電極の製造方法＞
　本実施形態に係るレドックスフロー電池用電極の製造方法は、第１多孔質層１２の片面に、ナノカーボン材料及びカーボンファイバーを含む分散液を塗布して乾燥させて、複合導電層１１を形成する工程と、複合導電層１１の両面のうち、第１多孔質層１２と反対側に位置する面に、ナノカーボン材料のみを含む分散液を塗布した後に乾燥させてナノカーボン層１３を形成する工程とを有する。 <Method of manufacturing electrode for redox flow battery>
In the method for manufacturing a redox flow battery electrode according to the present embodiment, a dispersion containing a nanocarbon material and carbon fibers is applied to one surface of the first porous layer 12 and dried to form the composite conductive layer 11. And a step of forming a nanocarbon layer 13 by applying a dispersion liquid containing only a nanocarbon material to one of both surfaces of the composite conductive layer 11 opposite to the first porous layer 12 and then drying it. Have and.
　ここで、第１多孔質層１２の片面に、ナノカーボン材料及びカーボンファイバーを含む分散液を塗布して複合導電層１１を形成することにより、複合導電層１１を第１多孔質層１２と一体化することが可能になる。また、複合導電層１１の両面のうち、第１多孔質層１２と反対側の面に、ナノカーボン材料のみを含む分散液を塗布してナノカーボン層１３を形成することにより、ナノカーボン層１３も複合導電層１１及び第１多孔質層１２と一体化することが可能になる。これにより、カーボンナノチューブを含む薄い層である、複合導電層１１やナノカーボン層１３を第１多孔質層１２に一体化して設けるときに、これらの層への破損が起こり難くなるため、レドックスフロー電池用電極の作製をより容易にすることができる。 Here, the composite conductive layer 11 is integrated with the first porous layer 12 by forming a composite conductive layer 11 by applying a dispersion liquid containing a nanocarbon material and carbon fibers on one surface of the first porous layer 12. It becomes possible to change. Further, the nanocarbon layer 13 is formed by applying the dispersion liquid containing only the nanocarbon material to the surface opposite to the first porous layer 12 of both surfaces of the composite conductive layer 11 to form the nanocarbon layer 13. Can be integrated with the composite conductive layer 11 and the first porous layer 12. Accordingly, when the composite conductive layer 11 or the nanocarbon layer 13 that is a thin layer containing carbon nanotubes is integrally provided on the first porous layer 12, damage to these layers is unlikely to occur, and thus the redox flow is prevented. The production of the battery electrode can be made easier.
　以下、図３（Ａ）～（Ｃ）を参照しながら、本実施形態に係る電極用導電シート材料の製造方法について、詳細に説明する。 Hereinafter, the method for manufacturing the conductive sheet material for electrodes according to the present embodiment will be described in detail with reference to FIGS. 3(A) to 3(C).
（ナノカーボン分散液の準備）
　本実施形態に係る製造方法に用いられる、ナノカーボン材料を含むナノカーボン分散液は、ナノカーボン材料を分散媒に分散させることにより得ることができる。 (Preparation of nanocarbon dispersion)
The nanocarbon dispersion liquid containing the nanocarbon material used in the manufacturing method according to the present embodiment can be obtained by dispersing the nanocarbon material in the dispersion medium.
　ここで、ナノカーボン材料は、三つの次元のうち少なくとも一つの次元についての大きさが１μｍ未満である炭素材料を含むことができる。その中でも、耐酸性及び耐酸化性の観点から、平均繊維径１μｍ未満のカーボンナノチューブを含むことが好ましい。また、分散媒としては、特に限定されず、例えば水を用いることができる。 Here, the nanocarbon material can include a carbon material having a size of less than 1 μm in at least one of the three dimensions. Among them, from the viewpoint of acid resistance and oxidation resistance, it is preferable to include carbon nanotubes having an average fiber diameter of less than 1 μm. The dispersion medium is not particularly limited, and water can be used, for example.
　ナノカーボン材料を分散媒に分散させる際、分散媒に分散剤を加えることが好ましく、これによりナノカーボン材料を均一に分散させ易くすることができる。ここで、分散剤としては、公知のものを用いることができ、例えば水溶性導電性高分子を用いることができる。 When dispersing the nanocarbon material in the dispersion medium, it is preferable to add a dispersant to the dispersion medium, which can facilitate uniform dispersion of the nanocarbon material. Here, as the dispersant, a known dispersant can be used, and for example, a water-soluble conductive polymer can be used.
　ナノカーボン材料を分散させてナノカーボン分散液を調製する方法は、特に限定されないが、ボールミル、ペイントシェーカー、超音波、ジェットミル等を用いる方法を挙げることができる。その中でも、ナノカーボン材料の損傷を抑えつつナノカーボン材料を均一に分散できる点では、超音波や湿式ジェットミルを用いる方法が好ましい。 The method for preparing the nanocarbon dispersion by dispersing the nanocarbon material is not particularly limited, and examples thereof include a method using a ball mill, a paint shaker, ultrasonic waves, a jet mill, and the like. Among them, the method using ultrasonic waves or a wet jet mill is preferable in that the nanocarbon material can be uniformly dispersed while suppressing damage to the nanocarbon material.
（複合分散液の準備）
　本実施形態に係る製造方法に用いられる、ナノカーボン材料とカーボンファイバーを含む複合分散液は、例えば、上述のナノカーボン分散液にカーボンファイバーをさらに分散させることにより得ることができる。また、ナノカーボン材料及びカーボンファイバーを同時に分散媒に分散させることで、複合分散液を得てもよい。 (Preparation of composite dispersion)
The composite dispersion liquid containing a nanocarbon material and carbon fibers used in the manufacturing method according to the present embodiment can be obtained, for example, by further dispersing carbon fibers in the above-mentioned nanocarbon dispersion liquid. Further, a composite dispersion liquid may be obtained by simultaneously dispersing the nanocarbon material and the carbon fiber in the dispersion medium.
　ここで、カーボンファイバーとしては、１μｍ以上の平均繊維径を有するものを用いることができる。 Here, carbon fibers having an average fiber diameter of 1 μm or more can be used.
　ナノカーボン分散液にカーボンファイバーを分散させる方法は、特に限定されないが、例えば、超音波、ボールミル、マグネティックスターラーを用いる方法を挙げることができる。 The method of dispersing the carbon fiber in the nanocarbon dispersion is not particularly limited, and examples thereof include a method using ultrasonic waves, a ball mill, and a magnetic stirrer.
（複合導電層の形成）
　次いで、図３（Ａ）に示すように、得られた複合分散液を、第１多孔質層１２の片面に塗布して乾燥させることで、複合導電層１１を形成する。 (Formation of composite conductive layer)
Next, as shown in FIG. 3(A), the obtained composite dispersion liquid is applied to one surface of the first porous layer 12 and dried to form the composite conductive layer 11.
　ここで、第１多孔質層１２としては、上述するような、１μｍ以上の平均繊維径を有するカーボンファイバーによって構成されるものを用いる。例えば、平均繊維径が１μｍ以上のカーボンファイバーからなる、織物やフェルト、ペーパー等を、所定の大きさに加工したものを用いることができる。 Here, as the first porous layer 12, the one made of carbon fibers having an average fiber diameter of 1 μm or more as described above is used. For example, a woven fabric, felt, paper or the like made of carbon fiber having an average fiber diameter of 1 μm or more and processed into a predetermined size can be used.
　第１多孔質層１２に複合分散液を塗布する手段としては、例えば、ロールコーター法やスプレー法などを用いることができる。そして、第１多孔質層１２に複合分散液を塗布した後、分散媒を留去することで、第１多孔質層１２の片面に複合導電層１１を形成することができる。 As a means for applying the composite dispersion liquid to the first porous layer 12, for example, a roll coater method or a spray method can be used. Then, after applying the composite dispersion liquid to the first porous layer 12, the dispersion medium is distilled off to form the composite conductive layer 11 on one surface of the first porous layer 12.
（ナノカーボン層の形成）
　次いで、図３（Ｂ）に示すように、複合導電層１１の両面のうち、第１多孔質層１２と反対側に位置する面に、ナノカーボン分散液を塗布してナノカーボン層１３を形成する。 (Formation of nanocarbon layer)
Next, as shown in FIG. 3B, a nanocarbon layer 13 is formed by applying a nanocarbon dispersion liquid to the surface of the composite conductive layer 11 located on the opposite side of the first porous layer 12 from both surfaces. To do.
　ここで、複合導電層１１にナノカーボン分散液を塗布する手段としては、例えば、ロールコーター法やスプレー法などを用いることができる。また、複合導電層１１にナノカーボン分散液を塗布した後、分散媒を留去することで、複合導電層１１にナノカーボン層１３を形成することができる。このようにして、第１多孔質層１２、複合導電層１１及びナノカーボン層１３の３層を有する積層体を得ることができる。 Here, as a means for applying the nanocarbon dispersion liquid to the composite conductive layer 11, for example, a roll coater method or a spray method can be used. Further, the nanocarbon layer 13 can be formed on the composite conductive layer 11 by applying the nanocarbon dispersion liquid to the composite conductive layer 11 and then distilling the dispersion medium. In this way, a laminate having the three layers of the first porous layer 12, the composite conductive layer 11 and the nanocarbon layer 13 can be obtained.
（第２多孔質層の形成）
　得られた積層体は、必要に応じて所定の大きさに加工した後、図３（Ｃ）に示すように、ナノカーボン層１３の両面のうち複合導電層１１と反対側に位置する面に、第２多孔質層１５を積層することが好ましい。ここで、第２多孔質層１５は、図３（Ｃ）に示すように極板１６に保持されていてもよい。この場合、極板１６に保持された第２多孔質層１５上に、ナノカーボン層１３、複合導電層１１及び第１多孔質層１２を順に有する積層体を積層することによって、レドックスフロー電池用電極１を得ることができる。 (Formation of second porous layer)
The obtained laminated body is processed into a predetermined size if necessary, and then, as shown in FIG. 3(C), on a surface of the nanocarbon layer 13 opposite to the composite conductive layer 11, the surface is located. It is preferable to stack the second porous layer 15. Here, the second porous layer 15 may be held by the electrode plate 16 as shown in FIG. In this case, for the redox flow battery, by stacking a laminate having the nanocarbon layer 13, the composite conductive layer 11 and the first porous layer 12 in this order on the second porous layer 15 held by the electrode plate 16. The electrode 1 can be obtained.
　ここで、第２多孔質層１５としては、第１多孔質層１２と同様に、１μｍ以上の平均繊維径を有するカーボンファイバーによって構成されるものを用いる。 Here, as the second porous layer 15, as with the first porous layer 12, a layer made of carbon fiber having an average fiber diameter of 1 μm or more is used.
　第２多孔質層１５は、第１多孔質層１２、複合導電層１１及びナノカーボン層１３を有する積層体のナノカーボン層１３に対向させて配置し、必要に応じて加熱しながらプレス成形することにより、第１多孔質層１２、複合導電層１１、ナノカーボン層１３を有する積層体と一体化させることができる。 The second porous layer 15 is disposed so as to face the nanocarbon layer 13 of the laminated body having the first porous layer 12, the composite conductive layer 11 and the nanocarbon layer 13, and is press-formed while being heated if necessary. Thereby, it can be integrated with the laminated body having the first porous layer 12, the composite conductive layer 11, and the nanocarbon layer 13.
　プレス成形する際のプレス圧と加熱温度は、予備実験により求めることができる。例えば、１０ＭＰａ～２０ＭＰａのプレス圧で圧力をかけた状態で、５０℃～２５０℃の温度で加熱することによりレドックスフロー電池用電極１を製造することができる。 The press pressure and heating temperature during press molding can be determined by preliminary experiments. For example, the redox flow battery electrode 1 can be manufactured by heating at a temperature of 50° C. to 250° C. under a pressure of 10 MPa to 20 MPa.
　なお、ナノカーボン層１３に、極板１６に保持されていない第２多孔質層１５を積層してもよく、この場合は、第２多孔質層１５の積層によって電極用導電シート材料を得ることができる。得られた電極用導電シート材料を所定の大きさに加工した後、必要に応じて第２多孔質層１５に極板１６を貼り付けることにより、レドックスフロー電池用電極１を得ることができる。 The nanocarbon layer 13 may be laminated with the second porous layer 15 not held by the electrode plate 16. In this case, the conductive sheet material for electrodes is obtained by laminating the second porous layer 15. You can The redox flow battery electrode 1 can be obtained by processing the obtained electrode conductive sheet material into a predetermined size and then attaching the electrode plate 16 to the second porous layer 15 if necessary.
［レドックスフロー電池の作製］
　このようにして作製されるレドックスフロー電池用電極１は、常法により、例えば図２に記載されるレドックスフロー電池２に組み込むことができる。ここで、レドックスフロー電池用電極１を正極電極１ａとして用いる場合、レドックスフロー電池用電極１をイオン交換膜６０と正極側の極板１６ａとの間に設ける。また、レドックスフロー電池用電極１を負極電極１ｂとして用いる場合、レドックスフロー電池用電極１をイオン交換膜６０と負極側の極板１６ｂとの間に設ける。 [Preparation of redox flow battery]
The redox flow battery electrode 1 thus produced can be incorporated into the redox flow battery 2 shown in FIG. 2 by a conventional method. Here, when the redox flow battery electrode 1 is used as the positive electrode 1a, the redox flow battery electrode 1 is provided between the ion exchange membrane 60 and the positive electrode plate 16a. When the redox flow battery electrode 1 is used as the negative electrode 1b, the redox flow battery electrode 1 is provided between the ion exchange membrane 60 and the negative electrode plate 16b.
　以下、本発明を実施例によりさらに詳細に説明するが、本発明はこれらの実施例に何ら限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
［実施例１］
１．ナノカーボン材料を含む分散液の調製
　純水３０ｍＬに、分散剤として水溶性導電性高分子であるポリイソチオナフテンスルホン酸０．３ｍｇを溶解した溶液を作製した。この溶液に、ナノカーボン材料であるカーボンナノチューブとして昭和電工株式会社製のＶＧＣＦ（登録商標）－Ｈ（平均繊維径１５０ｎｍ、平均繊維長１５μｍ）０．４ｇを加え、超音波洗浄機で３０分間にわたり分散処理することにより、ナノカーボン材料の分散液（分散液Ａ）を得た。 [Example 1]
1. Preparation of Dispersion Liquid Containing Nanocarbon Material A solution was prepared by dissolving 0.3 mg of polyisothionaphthenesulfonic acid, which is a water-soluble conductive polymer, as a dispersant in 30 mL of pure water. To this solution, 0.4 g of VGCF (registered trademark)-H (average fiber diameter: 150 nm, average fiber length: 15 μm) manufactured by Showa Denko Co., Ltd. as a carbon nanotube, which is a nanocarbon material, was added, and the mixture was ultrasonically cleaned for 30 minutes. By performing the dispersion treatment, a dispersion liquid (dispersion liquid A) of the nanocarbon material was obtained.
２．ナノカーボン材料とカーボンファイバーとを含む分散液の調製
　純水３０ｍＬに、分散剤として水溶性導電性高分子であるポリイソチオナフテンスルホン酸０．３ｍｇを溶解した溶液を作製した。この溶液に、ナノカーボン材料であるカーボンナノチューブとして昭和電工株式会社製のＶＧＣＦ（登録商標）－Ｈ（平均繊維径１５０ｎｍ、平均繊維長１５μｍ）０．３ｇとカーボンファイバーである大阪ガスケミカル製のドナカーボ・チョップ（登録商標）ＳＧ－２４９（平均繊維径１３μｍ、平均繊維長０．１１ｍｍ）０．２ｇを加え、超音波洗浄機で３０分間にわたり分散処理することで、ナノカーボン材料とカーボンファイバーを含む分散液（分散液Ｂ）を得た。 2. Preparation of Dispersion Liquid Containing Nanocarbon Material and Carbon Fiber A solution was prepared by dissolving 0.3 mg of polyisothionaphthenesulfonic acid, which is a water-soluble conductive polymer, as a dispersant in 30 mL of pure water. In this solution, 0.3 g of VGCF (registered trademark)-H (average fiber diameter 150 nm, average fiber length 15 μm) manufactured by Showa Denko KK as carbon nanotubes, which is a nanocarbon material, and carbon fiber donacarb made by Osaka Gas Chemicals, Inc. -Chop (registered trademark) SG-249 (average fiber diameter 13 μm, average fiber length 0.11 mm) 0.2 g was added, and the dispersion treatment was performed for 30 minutes with an ultrasonic cleaner to contain a nanocarbon material and carbon fibers. A dispersion (dispersion B) was obtained.
　この分散液Ｂにおけるカーボンファイバーの含有量は、ナノカーボン材料とカーボンファイバーの合計含有量を１００質量部としたとき、４０質量部である。 The content of carbon fiber in this dispersion B is 40 parts by mass when the total content of the nanocarbon material and the carbon fiber is 100 parts by mass.
３．複合導電層の形成
　第１多孔質層として、大きさ１００ｍｍ×１００ｍｍ、厚み０．１９ｍｍのカーボンペーパー（ＳＧＬカーボン社製、型番ＧＤＬ－２９ＡＡ）を配置し、前述のナノカーボン材料とカーボンファイバーとを含む分散液Ｂを、塗布手段としてスプレーを用いて塗布した。その後乾燥して、第１多孔質層に複合導電層を形成した。ここで、複合導電層が形成されている第１多孔質層の全体の厚さから、第１多孔質層の厚さｂを引いた厚さを、複合導電層の厚さａとして求めた。なお、複合導電層におけるカーボンファイバーの含有量は、分散液Ｂに含まれるナノカーボン材料とカーボンファイバーの合計含有量を１００質量部としたときの、分散液Ｂに含まれるカーボンファイバーの含有量（質量部）とした。 3. Formation of Composite Conductive Layer As the first porous layer, a carbon paper having a size of 100 mm×100 mm and a thickness of 0.19 mm (manufactured by SGL Carbon Co., model number GDL-29AA) is arranged, and the nanocarbon material and the carbon fiber described above are arranged. The dispersion liquid B containing was applied by using a spray as a coating means. Then, it dried and formed the composite conductive layer in the 1st porous layer. Here, the thickness obtained by subtracting the thickness b of the first porous layer from the total thickness of the first porous layer on which the composite conductive layer is formed was determined as the thickness a of the composite conductive layer. The content of carbon fibers in the composite conductive layer is the content of carbon fibers contained in dispersion B when the total content of the nanocarbon material and carbon fibers contained in dispersion B is 100 parts by mass ( Mass part).
４．ナノカーボン層の形成
　第１多孔質層に形成された複合導電層に、前述のナノカーボン材料の分散液を、塗布手段としてスプレーを用いて塗布した。その後乾燥して、複合導電層にナノカーボン層を形成し、それにより電極用導電シート材料を得た。ここで、電極用導電シート材料の厚さから、第１多孔質層及び複合導電層の厚さを引いた厚さを、ナノカーボン層の厚さｃとして求めた。 4. Formation of Nanocarbon Layer The composite conductive layer formed on the first porous layer was coated with the above-mentioned dispersion liquid of the nanocarbon material using a spray as a coating means. Then, it was dried to form a nanocarbon layer on the composite conductive layer, thereby obtaining a conductive sheet material for electrodes. Here, the thickness obtained by subtracting the thickness of the first porous layer and the composite conductive layer from the thickness of the electrode conductive sheet material was determined as the thickness c of the nanocarbon layer.
５．電極及び電池の作製
　極板として、国際公開第２０１８／０２６００５号の図４Ａに記載される集電板と同様の形状を有するものを用いた。より具体的に、極板としては、カーボンとプラスチックとを混練成形した平板状の成形材からなり、その主表面に凹部を有し、その凹部の周囲が周縁壁によって囲まれた形状を有するものを用いた。ここで、凹部のサイズは、４９ｍｍ×４９ｍｍ×深さ０．３７ｍｍ（すなわち、凹部を囲む周縁壁の高さは０．３７ｍｍ）であり、凹部を囲む周縁壁の幅は１ｍｍである。この凹部のサイズは、後述する第２多孔質層が凹部に隙間なく嵌まるサイズである。 5. Manufacture of Electrode and Battery As an electrode plate, one having the same shape as the current collector plate described in FIG. 4A of International Publication No. 2018/026005 was used. More specifically, the electrode plate is made of a flat-plate molding material obtained by kneading and molding carbon and plastic, and has a concave portion on its main surface, and the concave portion is surrounded by a peripheral wall. Was used. Here, the size of the recess is 49 mm×49 mm×depth 0.37 mm (that is, the height of the peripheral wall surrounding the recess is 0.37 mm), and the width of the peripheral wall surrounding the recess is 1 mm. The size of the recess is such that the second porous layer described below fits into the recess without any gap.
　この極板の電極に対向する面には、複数本の溝が互いに平行に形成されている。ここで、極板に形成されている溝の幅はそれぞれ０．５ｍｍ、溝の深さはそれぞれ１．０ｍｍであり、各々の溝の間隔は０．５ｍｍである。 A plurality of grooves are formed in parallel with each other on the surface of the electrode plate facing the electrode. Here, the width of each groove formed in the electrode plate is 0.5 mm, the depth of each groove is 1.0 mm, and the interval between the grooves is 0.5 mm.
　第２多孔質層として、大きさが４９ｍｍ×４９ｍｍのカーボンペーパー（東レ株式会社製、型番ＴＧＰ－Ｈ―１２０、厚さ０．３７ｍｍ）を用い、この第２多孔質層を極板の凹部に嵌合させた。 As the second porous layer, carbon paper having a size of 49 mm×49 mm (manufactured by Toray Industries, Inc., model number TGP-H-120, thickness 0.37 mm) was used, and this second porous layer was used as a concave portion of the electrode plate. Mated.
　次いで、電極用導電シート材料を５０ｍｍ×５０ｍｍの大きさに切り出し、電極用導電シート材料のナノカーボン層が第２多孔質層に面するように、電極用導電シート材料を極板の上に配置した。このようにして作製される電極を、正極電極及び負極電極として１枚ずつ用い、電極の第１多孔質層の側がそれぞれイオン交換膜に対向するように、これらの電極を配置した。ここで、両電極間のイオン交換膜としては、ナフィオン（登録商標）２１２（型番）を用いた。そして、２枚の極板の外側に集電板として金メッキを施した真鍮板を載置して、レドックスフロー電池の単セルを構成した。 Then, the conductive sheet material for electrodes is cut into a size of 50 mm×50 mm, and the conductive sheet material for electrodes is arranged on the electrode plate so that the nanocarbon layer of the conductive sheet material for electrodes faces the second porous layer. did. The electrodes thus prepared were used as a positive electrode and a negative electrode, respectively, and these electrodes were arranged such that the first porous layer side of the electrodes faced the ion exchange membrane. Here, Nafion (registered trademark) 212 (model number) was used as the ion exchange membrane between both electrodes. Then, a gold-plated brass plate was placed as a current collector plate on the outside of the two electrode plates to form a single cell of a redox flow battery.
６．充放電特性及び耐久性の評価
　得られたレドックスフロー電池について、充放電特性及び耐久性を評価した。正極側にバナジウムイオン（ＩＶ価）と硫酸を含む水溶液、負極側にバナジウムイオン（ＩＩＩ価）と硫酸を含む水溶液を電解液として導入し、それぞれ２５ｍＬの電解液をチューブポンプで循環させた。電解液の流量は、それぞれ６４ｍＬ／ｍｉｎに設定した。充放電時の電流は２．５Ａ（１００ｍＡ／ｃｍ２）とし、充電停止電圧を１．７５Ｖ、放電停止電圧を１．００Ｖとした。 6. Evaluation of Charge/Discharge Characteristics and Durability The obtained redox flow batteries were evaluated for charge/discharge characteristics and durability. An aqueous solution containing vanadium ions (IV valence) and sulfuric acid was introduced into the positive electrode side, and an aqueous solution containing vanadium ions (III valence) and sulfuric acid was introduced into the negative electrode side as electrolyte solutions, and 25 mL of each electrolyte solution was circulated by a tube pump. The flow rate of the electrolytic solution was set to 64 mL/min. The current during charge/discharge was 2.5 A (100 mA/cm 2 ), the charge stop voltage was 1.75 V, and the discharge stop voltage was 1.00 V.
　セル抵抗率は、充放電サイクル５回目における充電平均電圧及び放電平均電圧を求め、次の計算式の基づいて得られる値とした。
　セル抵抗率[Ω・ｃｍ２]＝（充電平均電圧[Ｖ]－放電平均電圧[Ｖ]）×電極面積[ｃｍ２]÷（２×充電電流[Ａ]） The cell resistivity was a value obtained by calculating the charge average voltage and the discharge average voltage at the fifth charge/discharge cycle and using the following formula.
Cell resistivity [Ω·cm 2 ]=(charge average voltage [V]−discharge average voltage [V])×electrode area [cm 2 ]÷(2×charge current [A])
　充放電効率（クーロン効率）は、充放電サイクル５回目の数値を測定した。 The charge/discharge efficiency (Coulomb efficiency) was measured at the fifth charge/discharge cycle.
　耐久性については、１０００回目の充放電サイクルを完了した後に、レドックスフロー電池を分解し、第２多孔質層及び極板を電極から取り外し、ナノカーボン層及び複合導電層へのひび割れの有無を目視により確認した。このとき、正極及び負極の両方で、ナノカーボン層及び複合導電層の両方にひび割れが認められないものを「○」、正極及び負極の少なくともいずれかで、ナノカーボン層及び複合導電層の一方又は両方にひび割れが生じたものを「×」とした。 Regarding the durability, after the 1000th charge/discharge cycle was completed, the redox flow battery was disassembled, the second porous layer and the electrode plate were removed from the electrodes, and the presence or absence of cracks in the nanocarbon layer and the composite conductive layer was visually checked. Confirmed by. At this time, in both the positive electrode and the negative electrode, those in which cracks are not observed in both the nanocarbon layer and the composite conductive layer are "○", and in at least one of the positive electrode and the negative electrode, one of the nanocarbon layer and the composite conductive layer or Those having cracks on both sides were marked with "x".
　［実施例２］
　「２．ナノカーボン材料とカーボンファイバーとを含む分散液の調製」において、カーボンファイバーの添加量を０．４ｇにした以外は、実施例１と同様に、レドックスフロー電池の単セルを構成した。このとき、分散液Ｂにおけるカーボンファイバーの含有量は、ナノカーボン材料とカーボンファイバーの合計含有量を１００質量部としたとき、５７質量部である。得られたレドックスフロー電池について、同様に充放電特性及び耐久性を評価した。 [Example 2]
In "2. Preparation of dispersion containing nanocarbon material and carbon fiber", a single cell of a redox flow battery was constructed in the same manner as in Example 1 except that the amount of carbon fiber added was 0.4 g. At this time, the content of the carbon fibers in the dispersion B is 57 parts by mass when the total content of the nanocarbon material and the carbon fibers is 100 parts by mass. Charge/discharge characteristics and durability of the obtained redox flow battery were evaluated in the same manner.
　［実施例３］
　「３．複合導電層の形成」において、第１多孔質層として、大きさ１００ｍｍ×１００ｍｍ、厚み０．１１ｍｍのカーボンペーパー（東レ株式会社製、型番ＴＧＰ－Ｈ―３０）を用いた以外は、実施例２と同様にして、レドックスフロー電池の単セルを構成した。得られたレドックスフロー電池について、同様に充放電特性及び耐久性を評価した。 [Example 3]
In "3. Formation of composite conductive layer", carbon paper having a size of 100 mm x 100 mm and a thickness of 0.11 mm (manufactured by Toray Industries, Inc., model number TGP-H-30) was used as the first porous layer, except that A single cell of a redox flow battery was constructed in the same manner as in Example 2. Charge/discharge characteristics and durability of the obtained redox flow battery were evaluated in the same manner.
　［実施例４］
　「１．ナノカーボン材料を含む分散液の調製」において、ナノカーボン材料（カーボンナノチューブ）である昭和電工株式会社製のＶＧＣＦ（登録商標）－Ｈ（平均繊維径１５０ｎｍ、平均繊維長１５μｍ）の添加量を０．５ｇにした。また、「２．ナノカーボン材料とカーボンファイバーとを含む分散液の調製」において、ナノカーボン材料（カーボンナノチューブ）である昭和電工株式会社製のＶＧＣＦ（登録商標）－Ｈ（平均繊維径１５０ｎｍ、平均繊維長１５μｍ）の添加量を０．４ｇにした。このとき、分散液Ｂにおけるカーボンファイバーの含有量は、ナノカーボン材料とカーボンファイバーの合計含有量を１００質量部としたとき、５０質量部である。それら以外は、実施例３と同様にして、レドックスフロー電池の単セルを構成した。得られたレドックスフロー電池について、同様に充放電特性及び耐久性を評価した。 [Example 4]
In “1. Preparation of dispersion containing nanocarbon material”, addition of VGCF (registered trademark)-H (average fiber diameter 150 nm, average fiber length 15 μm) manufactured by Showa Denko KK, which is a nanocarbon material (carbon nanotube) The amount was 0.5 g. Moreover, in “2. Preparation of dispersion containing nanocarbon material and carbon fiber”, VGCF (registered trademark)-H (average fiber diameter 150 nm, average, manufactured by Showa Denko KK, which is a nanocarbon material (carbon nanotube), is used. The amount of the fiber length (15 μm) added was 0.4 g. At this time, the content of the carbon fiber in the dispersion B is 50 parts by mass when the total content of the nanocarbon material and the carbon fiber is 100 parts by mass. Except for these, a single cell of a redox flow battery was constructed in the same manner as in Example 3. Charge/discharge characteristics and durability of the obtained redox flow battery were evaluated in the same manner.
　［実施例５］
　「１．ナノカーボン材料を含む分散液の調製」及び「２．ナノカーボン材料とカーボンファイバーとを含む分散液の調製」において、ＶＧＣＦ―Ｈの代わりにグラフェン（ＸＧサイエンス社製、ｘＧｎＰ－Ｃ－３００）を用いた以外は、実施例１と同様にして、レドックスフロー電池の単セルを構成した。得られたレドックスフロー電池について、同様に充放電特性及び耐久性を評価した。 [Example 5]
In “1. Preparation of Dispersion Liquid Containing Nanocarbon Material” and “2. Preparation of Dispersion Liquid Containing Nanocarbon Material and Carbon Fiber”, instead of VGCF-H, graphene (xGnP-C- manufactured by XG Science Co., Ltd. A single cell of a redox flow battery was constructed in the same manner as in Example 1 except that 300) was used. Charge/discharge characteristics and durability of the obtained redox flow battery were evaluated in the same manner.
　［比較例１］
　国際公開第２０１６／１０４６１３号の実施例１３と同様の導電性シートを用いて、レドックスフロー電池の単セルを構成した。ここで、国際公開第２０１６／１０４６１３号の実施例１３に記載の導電性シートは、ナノカーボン材料とカーボンファイバーの合計含有量を１００質量部としたときに、カーボンナノチューブとして、ＶＧＣＦ－Ｈを４５質量部、ＶＧＣＦ（登録商標）－Ｘ（平均繊維径１５ｎｍ、平均繊維長３μｍ、昭和電工株式会社製）を５質量部含有し、また、カーボンファイバーとして、ドナカーボ・チョップＳＧ－２４９を５０質量部含有している。 [Comparative Example 1]
A single cell of a redox flow battery was constructed by using the same conductive sheet as in Example 13 of WO 2016/104613. Here, in the conductive sheet described in Example 13 of WO2016/104613, when the total content of the nanocarbon material and the carbon fiber is 100 parts by mass, VGCF-H of 45 is used as the carbon nanotube. 5 parts by mass of VGCF (registered trademark)-X (average fiber diameter 15 nm, average fiber length 3 μm, manufactured by Showa Denko KK), and 50 parts by mass of Dona Carbo Chop SG-249 as carbon fiber. Contains.
　この導電性シートを、５０ｍｍ×５０ｍｍの大きさに切り出し、導電性シートの一方の面が第２多孔質層に面するように、導電性シートを極板の上に配置した。次いで、第１多孔質層を５０ｍｍ×５０ｍｍの大きさに切り出し、第１多孔質層が上記導電性シートの他方の面に重なるように配置した。それ以外は、実施例１と同様にして、レドックスフロー電池の単セルを構成した。すなわち、比較例１で構成したレドックスフロー電池の単セルは、ナノカーボン層を有しない。得られたレドックスフロー電池について、同様に充放電特性及び耐久性を評価した。 This conductive sheet was cut into a size of 50 mm×50 mm, and the conductive sheet was placed on the electrode plate so that one surface of the conductive sheet faced the second porous layer. Then, the first porous layer was cut into a size of 50 mm×50 mm, and the first porous layer was arranged so as to overlap with the other surface of the conductive sheet. A single cell of a redox flow battery was constructed in the same manner as in Example 1 except for the above. That is, the single cell of the redox flow battery configured in Comparative Example 1 does not have the nanocarbon layer. Charge/discharge characteristics and durability of the obtained redox flow battery were evaluated in the same manner.
　［比較例２］
　第１多孔質層として、大きさ５０ｍｍ×５０ｍｍのカーボンペーパー（東レ株式会社製、型番ＴＧＰ－Ｈ―３０）を用いた以外は、比較例１と同様にして、レドックスフロー電池の単セルを構成した。すなわち、比較例２で構成したレドックスフロー電池の単セルも、比較例１と同様にナノカーボン層を有しない。得られたレドックスフロー電池について、同様に充放電特性及び耐久性を評価した。 [Comparative example 2]
A single cell of a redox flow battery was constructed in the same manner as in Comparative Example 1 except that carbon paper having a size of 50 mm×50 mm (Toray Industries, Inc., model number TGP-H-30) was used as the first porous layer. did. That is, the single cell of the redox flow battery configured in Comparative Example 2 also does not have the nanocarbon layer as in Comparative Example 1. Charge/discharge characteristics and durability of the obtained redox flow battery were evaluated in the same manner.
　表１に、実施例１～５、比較例１～２における各種条件と、セル抵抗率、充放電効率（クーロン効率）、耐久性について示す。 Table 1 shows various conditions in Examples 1 to 5 and Comparative Examples 1 to 2, cell resistivity, charge/discharge efficiency (Coulomb efficiency), and durability.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　実施例１～５の電極は、ナノカーボン材料及び平均繊維径が１μｍ以上のカーボンファイバーの双方で構成される複合導電層と、複合導電層の両面のうち一方の面に位置し、カーボンファイバーで構成される第１多孔質層と、複合導電層の両面のうち他方の面に位置し、ナノカーボン材料で構成されるナノカーボン層とを有することで、ナノカーボン層を有しない比較例１～２の電極に比べて、レドックスフロー電池のセル抵抗率が低減されることがわかった。また、実施例１～５の電極を構成する複合導電層及びナノカーボン層の合計厚さは、ナノカーボン層を有しない比較例１～２の電極を構成する複合導電層の厚さよりも薄いにもかかわらず、電極材料の破損が生じなかったことから、このような積層構成の電極とすることで、電極材料の破損が起こり難くなり、その結果、電極の作製が容易になることがわかった。 The electrodes of Examples 1 to 5 were located on one of both surfaces of the composite conductive layer and a composite conductive layer composed of both a nanocarbon material and carbon fibers having an average fiber diameter of 1 μm or more. Comparative Example 1 that does not have a nanocarbon layer by including the first porous layer that is configured and the nanocarbon layer that is located on the other surface of both surfaces of the composite conductive layer and that is formed of a nanocarbon material It was found that the cell resistivity of the redox flow battery was reduced as compared with the No. 2 electrode. Further, the total thickness of the composite conductive layer and the nanocarbon layer forming the electrodes of Examples 1 to 5 should be smaller than the thickness of the composite conductive layer forming the electrodes of Comparative Examples 1 and 2 having no nanocarbon layer. Nonetheless, since the electrode material was not damaged, it was found that the electrode material having such a laminated structure is less likely to be damaged, and as a result, the electrode is easily manufactured. ..
　また、表１には示していないが、実施例１～５の電極は、比較例１～２の電極とは異なり、充放電後にひび割れが生じないため、電極の機械的強度を高められることも確認した。 Further, although not shown in Table 1, unlike the electrodes of Comparative Examples 1 and 2, the electrodes of Examples 1 to 5 do not cause cracks after charge and discharge, so that the mechanical strength of the electrodes can be increased. confirmed.
　１　　　レドックスフロー電池用電極
　１ａ　　正極電極
　１ｂ　　負極電極
　１１　　複合導電層
　１２　　第１多孔質層
　１３　　ナノカーボン層
　１５　　第２多孔質層
　１６、１６ａ、１６ｂ　極板
　１６１　溝部
　２　　　レドックスフロー電池
　４１　　正極セル
　４２　　正極電解液タンク
　４３　　正極往路配管
　４４　　正極復路配管
　４５、５５　ポンプ
　５１　　負極セル
　５２　　負極電解液タンク
　５３　　負極往路配管
　５４　　負極復路配管
　６　　　電池セル
　６０　　イオン交換膜
　８１　　交流電源
　８２　　負荷電源
　９　　　交流／直流変換器 1 Redox Flow Battery Electrode 1a Positive Electrode 1b Negative Electrode 11 Composite Conductive Layer 12 First Porous Layer 13 Nanocarbon Layer 15 Second Porous Layer 16, 16a, 16b Electrode Plate 161 Groove 2 Redox Flow Battery 41 Positive Cell 42 Positive Electrode Electrolyte solution tank 43 Positive electrode forward piping 44 Positive electrode return piping 45, 55 Pump 51 Negative electrode cell 52 Negative electrode electrolytic tank 53 Negative outgoing piping 54 Negative return piping 6 Battery cell 60 Ion exchange membrane 81 AC power supply 82 Load power supply 9 AC/DC converter

Claims (12)

  1. 　ナノカーボン材料及び平均繊維径が１μｍ以上のカーボンファイバーの双方で構成される複合導電層と、
    　前記複合導電層の両面のうち、一方の面に位置し、前記カーボンファイバーで構成される第１多孔質層と、
    　前記複合導電層の他方の面に位置し、前記ナノカーボン材料で構成されるナノカーボン層と、
    を有する、レドックスフロー電池用電極。     A composite conductive layer composed of both a nanocarbon material and carbon fibers having an average fiber diameter of 1 μm or more,
    A first porous layer which is located on one surface of both surfaces of the composite conductive layer and is composed of the carbon fiber;
    Located on the other surface of the composite conductive layer, a nanocarbon layer composed of the nanocarbon material,
    An electrode for a redox flow battery having:
  2. 　前記ナノカーボン層および前記複合導電層の厚さ寸法は、いずれも０．０１ｍｍ～０．２０ｍｍであり、前記第１多孔質層の厚さ寸法は０．０５ｍｍ～０．３０ｍｍである、請求項１に記載のレドックスフロー電池用電極。 The thickness dimension of each of the nanocarbon layer and the composite conductive layer is 0.01 mm to 0.20 mm, and the thickness dimension of the first porous layer is 0.05 mm to 0.30 mm. 1. The redox flow battery electrode according to 1.
  3. 　前記ナノカーボン層の両面のうち、前記複合導電層と反対側の面に位置し、前記カーボンファイバーで構成される第２多孔質層をさらに有する、請求項１又は２に記載のレドックスフロー電池用電極。 The redox flow battery according to claim 1 or 2, further comprising a second porous layer which is located on a surface opposite to the composite conductive layer on both surfaces of the nanocarbon layer and which is composed of the carbon fiber. electrode.
  4. 　前記第２多孔質層の厚さ寸法は０．１０ｍｍ～０．５０ｍｍである、請求項３に記載のレドックスフロー電池用電極。 The electrode for redox flow battery according to claim 3, wherein the thickness dimension of the second porous layer is 0.10 mm to 0.50 mm.
  5. 　前記第１多孔質層の厚さ寸法は、前記第２多孔質層の厚さ寸法よりも小さい、請求項３又は４に記載のレドックスフロー電池用電極。 The electrode for a redox flow battery according to claim 3 or 4, wherein the thickness dimension of the first porous layer is smaller than the thickness dimension of the second porous layer.
  6. 　前記ナノカーボン材料は、平均繊維径１μｍ未満のカーボンナノチューブを含む、請求項１～５のいずれか一項に記載のレドックスフロー電池用電極。 The redox flow battery electrode according to any one of claims 1 to 5, wherein the nanocarbon material includes carbon nanotubes having an average fiber diameter of less than 1 µm.
  7. 　前記複合導電層が、前記ナノカーボン材料と前記カーボンファイバーの合計１００質量部に対し、前記カーボンファイバーを２０質量部～９０質量部含む、請求項１～６のいずれか一項に記載のレドックスフロー電池用電極。 7. The redox flow according to claim 1, wherein the composite conductive layer contains 20 parts by mass to 90 parts by mass of the carbon fiber with respect to 100 parts by mass of the total of the nanocarbon material and the carbon fiber. Battery electrode.
  8. 　請求項１～７のいずれか一項に記載のレドックスフロー電池用電極を有する、レドックスフロー電池。 A redox flow battery having the electrode for redox flow battery according to any one of claims 1 to 7.
  9. 　イオン交換膜と極板との間に、請求項１～７のいずれか一項に記載のレドックスフロー電池用電極を、前記第１多孔質層が前記イオン交換膜と対向するように備える、レドックスフロー電池。 A redox comprising the electrode for redox flow battery according to any one of claims 1 to 7 between the ion exchange membrane and the electrode plate such that the first porous layer faces the ion exchange membrane. Flow battery.
  10. 　ナノカーボン材料及び平均繊維径が１μｍ以上のカーボンファイバーの双方で構成される複合導電層と、
    　前記複合導電層の両面のうち、一方の面に位置し、前記カーボンファイバーで構成される第１多孔質層と、
    　前記複合導電層の他方の面に位置し、前記ナノカーボン材料で構成されるナノカーボン層と、
    を有する、電極用導電シート材料。     A composite conductive layer composed of both a nanocarbon material and carbon fibers having an average fiber diameter of 1 μm or more,
    A first porous layer which is located on one surface of both surfaces of the composite conductive layer and is composed of the carbon fiber;
    Located on the other surface of the composite conductive layer, a nanocarbon layer composed of the nanocarbon material,
    A conductive sheet material for an electrode, comprising:
  11. 　前記ナノカーボン層の両面のうち、前記複合導電層と反対側の面に位置し、前記カーボンファイバーで構成される第２多孔質層をさらに有する、請求項１０に記載の電極用導電シート材料。 The conductive sheet material for an electrode according to claim 10, further comprising a second porous layer which is located on a surface opposite to the composite conductive layer on both surfaces of the nanocarbon layer and which is composed of the carbon fiber.
  12. 　レドックスフロー電池用電極の製造方法であって、
    　第１多孔質層の片面に、ナノカーボン材料及びカーボンファイバーを含む複合分散液を塗布して乾燥させて、複合導電層を形成する工程と、
    　前記複合導電層の両面のうち、前記第１多孔質層と反対側に位置する面に、前記ナノカーボン材料を含むナノカーボン分散液を塗布した後に乾燥させて、ナノカーボン層を形成する工程と、
    を有することを特徴とする、レドックスフロー電池用電極の製造方法。     A method of manufacturing an electrode for a redox flow battery, comprising:
    A step of applying a composite dispersion liquid containing a nanocarbon material and carbon fibers to one surface of the first porous layer and drying it to form a composite conductive layer;
    A step of forming a nanocarbon layer by applying a nanocarbon dispersion liquid containing the nanocarbon material to a surface of the composite conductive layer opposite to the first porous layer on both sides of the composite conductive layer and then drying it. ,
    A method for manufacturing an electrode for a redox flow battery, comprising:
PCT/JP2019/046255 2018-11-26 2019-11-26 Electrode for redox flow battery, method for manufacturing same, redox flow battery, and conductive sheet material for electrode WO2020111084A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016104613A1 (en) * 2014-12-26 2016-06-30 昭和電工株式会社 Electrode for redox flow batteries, and redox flow battery
WO2018062356A1 (en) * 2016-09-30 2018-04-05 昭和電工株式会社 Redox flow battery

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016104613A1 (en) * 2014-12-26 2016-06-30 昭和電工株式会社 Electrode for redox flow batteries, and redox flow battery
WO2018062356A1 (en) * 2016-09-30 2018-04-05 昭和電工株式会社 Redox flow battery

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