WO2023042280A1 - 電極、電池セル、セルスタック、電池システム、及び電極の製造方法 - Google Patents

電極、電池セル、セルスタック、電池システム、及び電極の製造方法 Download PDF

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WO2023042280A1
WO2023042280A1 PCT/JP2021/033821 JP2021033821W WO2023042280A1 WO 2023042280 A1 WO2023042280 A1 WO 2023042280A1 JP 2021033821 W JP2021033821 W JP 2021033821W WO 2023042280 A1 WO2023042280 A1 WO 2023042280A1
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Prior art keywords
electrode
electrode material
sheet
thickness
less
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PCT/JP2021/033821
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English (en)
French (fr)
Japanese (ja)
Inventor
雄大 越智
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Sumitomo Electric Industries Ltd
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Sumitomo Electric Industries Ltd
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Application filed by Sumitomo Electric Industries Ltd filed Critical Sumitomo Electric Industries Ltd
Priority to CN202180007296.8A priority Critical patent/CN116323123A/zh
Priority to EP21904618.2A priority patent/EP4177022A1/en
Priority to PCT/JP2021/033821 priority patent/WO2023042280A1/ja
Priority to US17/786,218 priority patent/US20240162411A1/en
Priority to JP2022515795A priority patent/JP7415255B2/ja
Publication of WO2023042280A1 publication Critical patent/WO2023042280A1/ja
Priority to JP2023140097A priority patent/JP2023155421A/ja
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
    • B26D—CUTTING; DETAILS COMMON TO MACHINES FOR PERFORATING, PUNCHING, CUTTING-OUT, STAMPING-OUT OR SEVERING
    • B26D1/00—Cutting through work characterised by the nature or movement of the cutting member or particular materials not otherwise provided for; Apparatus or machines therefor; Cutting members therefor
    • B26D1/01—Cutting through work characterised by the nature or movement of the cutting member or particular materials not otherwise provided for; Apparatus or machines therefor; Cutting members therefor involving a cutting member which does not travel with the work
    • B26D1/02—Cutting through work characterised by the nature or movement of the cutting member or particular materials not otherwise provided for; Apparatus or machines therefor; Cutting members therefor involving a cutting member which does not travel with the work having a stationary cutting member
    • B26D1/025—Cutting through work characterised by the nature or movement of the cutting member or particular materials not otherwise provided for; Apparatus or machines therefor; Cutting members therefor involving a cutting member which does not travel with the work having a stationary cutting member for thin material, e.g. for sheets, strips or the like
    • 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
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
    • B26D—CUTTING; DETAILS COMMON TO MACHINES FOR PERFORATING, PUNCHING, CUTTING-OUT, STAMPING-OUT OR SEVERING
    • B26D3/00—Cutting work characterised by the nature of the cut made; Apparatus therefor
    • B26D3/28—Splitting layers from work; Mutually separating layers by cutting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
    • B26D—CUTTING; DETAILS COMMON TO MACHINES FOR PERFORATING, PUNCHING, CUTTING-OUT, STAMPING-OUT OR SEVERING
    • B26D3/00—Cutting work characterised by the nature of the cut made; Apparatus therefor
    • B26D3/30—Halving devices, e.g. for halving buns
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
    • B26D—CUTTING; DETAILS COMMON TO MACHINES FOR PERFORATING, PUNCHING, CUTTING-OUT, STAMPING-OUT OR SEVERING
    • B26D7/00—Details of apparatus for cutting, cutting-out, stamping-out, punching, perforating, or severing by means other than cutting
    • B26D7/01—Means for holding or positioning work
    • B26D7/015—Means for holding or positioning work for sheet material or piles of sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
    • B26D—CUTTING; DETAILS COMMON TO MACHINES FOR PERFORATING, PUNCHING, CUTTING-OUT, STAMPING-OUT OR SEVERING
    • B26D7/00—Details of apparatus for cutting, cutting-out, stamping-out, punching, perforating, or severing by means other than cutting
    • B26D7/06—Arrangements for feeding or delivering work of other than sheet, web, or filamentary form
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
    • B26D—CUTTING; DETAILS COMMON TO MACHINES FOR PERFORATING, PUNCHING, CUTTING-OUT, STAMPING-OUT OR SEVERING
    • B26D7/00—Details of apparatus for cutting, cutting-out, stamping-out, punching, perforating, or severing by means other than cutting
    • B26D7/06—Arrangements for feeding or delivering work of other than sheet, web, or filamentary form
    • B26D7/0683—Arrangements for feeding or delivering work of other than sheet, web, or filamentary form specially adapted for elongated articles
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4209—Inorganic fibres
    • D04H1/4242—Carbon fibres
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06H—MARKING, INSPECTING, SEAMING OR SEVERING TEXTILE MATERIALS
    • D06H7/00—Apparatus or processes for cutting, or otherwise severing, specially adapted for the cutting, or otherwise severing, of textile materials
    • 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
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
    • 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
    • H01M4/8605—Porous electrodes
    • 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
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/023—Porous and characterised by the material
    • H01M8/0234—Carbonaceous material
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2404/00—Parts for transporting or guiding the handled material
    • B65H2404/70—Other elements in edge contact with handled material, e.g. registering, orientating, guiding devices
    • B65H2404/74—Guiding means
    • B65H2404/742—Guiding means for guiding transversely
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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
    • H01M8/184—Regeneration by electrochemical means
    • H01M8/188—Regeneration by electrochemical means by recharging of redox couples containing fluids; Redox flow type batteries
    • 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
    • Y02E60/10—Energy storage using batteries
    • 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 disclosure relates to electrodes, battery cells, cell stacks, battery systems, and methods of manufacturing electrodes.
  • Patent Document 1 discloses the following.
  • a roll of carbon fiber nonwoven fabric is prepared.
  • the width of the carbon fiber nonwoven fabric is 1.2m to 1.5m.
  • the length of the carbon fiber nonwoven fabric is 20m to 70m.
  • the roll-shaped carbon fiber nonwoven fabric runs by being unwound by a winder.
  • the running carbon fiber nonwoven fabric passes between a pair of vertically facing transport rollers.
  • the carbon fiber nonwoven fabric passed between the pair of transport rollers is cut by a band knife arranged near the outlet of the pair of transport rollers. This cutting produces two layers of carbon fiber nonwoven of uniform thickness.
  • the two carbon fiber nonwoven fabric layers thus produced are respectively wound by different winding machines.
  • the electrodes of the present disclosure are An electrode for use in a battery system, comprising: Equipped with a sheet made of nonwoven fabric containing multiple carbon fibers, The sheet has a first surface and a second surface facing each other in a direction along the thickness of the sheet, The plurality of carbon fibers includes a first carbon fiber, The first carbon fiber has at least one of a cut surface facing the first surface and a cut surface facing the second surface, The width of the sheet is 1000 mm or less, The sheet has a length of 2000 mm or less.
  • a battery cell of the present disclosure includes an electrode of the present disclosure.
  • a cell stack of the present disclosure includes a plurality of battery cells of the present disclosure.
  • the battery system of the present disclosure includes the battery cell of the present disclosure or the cell stack of the present disclosure.
  • a method for manufacturing an electrode of the present disclosure includes: A method for manufacturing an electrode used in a battery system, comprising: preparing a sheet-shaped first electrode material having a width of 1000 mm or less and a length of 2000 mm or less and made of a nonwoven fabric containing a plurality of carbon fibers; A step of cutting the first electrode material to produce the electrode, The step of fabricating the electrode includes: feeding the first electrode material to a cutting tool by rotation of a first roller and a second roller sandwiching the first electrode material; and slicing the first electrode material with the cutting tool so that the thickness of the first electrode material is reduced.
  • FIG. 1 is a schematic perspective view showing electrodes of the embodiment.
  • FIG. 2 is a schematic diagram showing a part of the II-II section of FIG.
  • FIG. 3 is a schematic cross-sectional view schematically showing a cross section of carbon fibers that constitute the electrode of the embodiment.
  • FIG. 4 is an explanatory diagram showing measurement points for measuring the thickness of the electrode according to the embodiment.
  • FIG. 5 is an explanatory diagram showing measurement points for measuring the thickness of the electrode according to the embodiment.
  • FIG. 6 is a perspective view for explaining the method of manufacturing the electrode of the embodiment.
  • FIG. 7 is a top view for explaining the method for manufacturing the electrode of the embodiment.
  • FIG. 8 is a cross-sectional view for explaining the method for manufacturing the electrode of the embodiment.
  • FIG. 9 is a schematic configuration diagram of the redox flow battery system of the embodiment.
  • FIG. 10 is a schematic configuration diagram of a cell stack included in the redox flow battery system of the embodiment.
  • One of the purposes of the present disclosure is to provide an electrode with small variations in thickness.
  • An object of the present disclosure is to provide a battery cell including the electrode.
  • An object of the present disclosure is to provide a cell stack including the battery cells described above.
  • An object of the present disclosure is to provide a battery system including the battery cell or the cell stack.
  • An object of the present disclosure is to provide an electrode manufacturing method capable of manufacturing an electrode with small variations in thickness.
  • the electrodes of the present disclosure have small thickness variations.
  • the battery cell, cell stack, and battery system of the present disclosure can easily increase current efficiency and reduce cell resistivity.
  • the electrode manufacturing method of the present disclosure can manufacture electrodes with small variations in thickness.
  • An electrode for use in a battery system comprising: Equipped with a sheet made of nonwoven fabric containing multiple carbon fibers, The sheet has a first surface and a second surface facing each other in a direction along the thickness of the sheet, The plurality of carbon fibers includes a first carbon fiber, The first carbon fiber has at least one of a cut surface facing the first surface and a cut surface facing the second surface, The width of the sheet is 1000 mm or less, The sheet has a length of 2000 mm or less.
  • the electrode containing the first carbon fibers is manufactured by the electrode manufacturing method described below.
  • the electrode manufacturing method is a method of manufacturing an electrode by slicing the first electrode material so that the thickness of the first electrode material becomes thin.
  • the width of the sliced first electrode material is 1000 mm or less, and the length of the first electrode material is 2000 mm or less. That is, the width of the first electrode material is narrow and the length of the first electrode material is short.
  • the rotation of the first roller and the second roller sandwiching the first electrode material feeds the first electrode material to a cutting tool that slices the first electrode material.
  • the first electrode material is sliced without substantially applying tension to the first electrode material.
  • substantially no tension acts means that tension associated with winding the first electrode material downstream of the first roller and the second roller does not act.
  • tension acts on the first electrode material, and the produced electrode has a first thickness variation described below that exceeds 25%. . It is permissible for the tension resulting from being sandwiched between the first roller and the second roller to act on the first electrode material. Therefore, in the electrode manufacturing method, the same position in the thickness direction of the first electrode material is likely to be cut along the width direction and the length direction of the first electrode material.
  • the electrodes facilitate construction of battery cells, cell stacks, and battery systems with excellent battery performance. Specifically, the electrodes facilitate construction of battery cells, cell stacks, and battery systems with high current efficiency and low cell resistivity.
  • the sheet preferably has an average thickness of 0.5 mm or more and 3 mm or less.
  • a sheet with an average thickness of 0.5 mm or more facilitates construction of battery cells, cell stacks, and RF battery systems with excellent battery performance. Moreover, a sheet having an average thickness of 0.5 mm or more has excellent mechanical strength.
  • the carbon fiber nonwoven fabric having a wide width and a long length is cut while tension is applied to the carbon fiber nonwoven fabric. Since the technique of Patent Document 1 described above is a method for producing two sheets of electrodes having a uniform thickness, the thickness of the carbon fiber nonwoven fabric is also reduced when an electrode having a small thickness is produced. As the thickness of the carbon fiber nonwoven fabric becomes thinner, it becomes more difficult to uniformly apply the tension in the width direction of the carbon fiber nonwoven fabric. Therefore, the thinner the carbon fiber nonwoven fabric, the more difficult it is to cut the same position in the thickness direction of the carbon fiber nonwoven fabric along the width direction of the carbon fiber nonwoven fabric.
  • the sheet has a length of 500 mm or more.
  • Sheets with a length of 500 mm or more facilitate construction of high-power battery cells, cell stacks, and battery systems.
  • Variation in thickness of the sheet is preferably 25% or less.
  • the variation in thickness is 25% or less, the battery performance of the electrode tends to be uniform over the entire area of the electrode. This variation in thickness is the first variation in thickness, which will be described later.
  • Variation in basis weight of the sheet is preferably 25% or less.
  • variation in basis weight is 25% or less, the electrical conductivity of the electrode and the fluidity of the electrolytic solution tend to be uniform over the entire electrode.
  • This variation in basis weight refers to the first variation in basis weight, which will be described later.
  • the basis weight of the sheet is 50 g/m 2 or more and 350 g/m 2 or less.
  • a sheet having a basis weight of 50 g/m 2 or more tends to increase contact points between carbon fibers, and thus tends to increase conductivity.
  • a sheet having a basis weight of 350 g/m 2 or less easily secures voids, and thus has excellent flowability of the electrolytic solution.
  • the plurality of carbon fibers may include carbon fibers having a plurality of pleats on the surface.
  • the surface area of the carbon fiber tends to increase. Carbon fibers with a large surface area tend to increase the reaction area in contact with the electrolytic solution. Therefore, the reactivity between the electrode and the electrolyte is improved.
  • the density of the plurality of carbon fibers is 1.5 g/cm 3 or more and 2.2 g/cm 3 or less; It is preferable that the sheet has a porosity of 60% or more and 99% or less.
  • the density of the carbon fiber is 1.5 g/cm 3 or more, the conductive component is large. Electrodes containing this carbon fiber facilitate construction of battery cells with low internal resistance. If the density of the carbon fiber is 2.2 g/cm 3 or less, the stiffness of the carbon fiber is not too high. An electrode containing this carbon fiber facilitates construction of a battery cell in which the diaphragm is less likely to be damaged.
  • the porosity of the sheet is 60% or more, there are more voids than a sheet with a porosity of less than 60%. This sheet is excellent in electrolyte solution flowability. If the porosity of the sheet is 99% or less, the electrode is excellent in battery reactivity.
  • a battery cell according to one aspect of the present disclosure is The electrode according to any one of (1) to (8) above is provided.
  • the battery cell includes electrodes with small variations in thickness, it is easy to increase the current efficiency and reduce the cell resistivity.
  • a cell stack according to one aspect of the present disclosure includes: A plurality of battery cells according to (9) are provided.
  • the cell stack includes a plurality of battery cells, it is easy to increase current efficiency and reduce cell resistivity.
  • a battery system according to an aspect of the present disclosure includes: The battery cell according to (9) above or the cell stack according to (10) above is provided.
  • the battery system includes the battery cells or the cell stack, it is easy to increase the current efficiency and reduce the cell resistivity.
  • a method for manufacturing an electrode according to one aspect of the present disclosure includes: A method for manufacturing an electrode used in a battery system, comprising: preparing a sheet-shaped first electrode material having a width of 1000 mm or less and a length of 2000 mm or less and made of a nonwoven fabric containing a plurality of carbon fibers; A step of cutting the first electrode material to produce the electrode, The step of fabricating the electrode includes: feeding the first electrode material to a cutting tool by rotation of a first roller and a second roller sandwiching the first electrode material; and slicing the first electrode material with the cutting tool so that the thickness of the first electrode material is reduced.
  • the manufacturing method described above can manufacture electrodes with small variations in thickness.
  • the width of the first electrode material to be sliced is 1000 mm or less, and the length of the first electrode material is 2000 mm or less. That is, the width of the first electrode material is narrow and the length of the first electrode material is short.
  • the rotation of the first roller and the second roller sandwiching the first electrode material feeds the first electrode material to the cutting tool for slicing the first electrode material. That is, in the manufacturing method described above, the first electrode material is sliced without substantially applying tension to the first electrode material. Therefore, the manufacturing method described above facilitates cutting at the same position in the thickness direction of the first electrode material along the width direction and the length direction of the first electrode material.
  • the first electrode material may be sliced so that the electrode has an average thickness of 0.5 mm or more and 3 mm or less.
  • an electrode with small variations in thickness can be manufactured even if the average thickness satisfies the above range.
  • the first electrode material In the step of preparing the first electrode material, preparing the first electrode material having a thickness more than twice the average thickness of the electrode; In the step of slicing the first electrode material, the first electrode material may be sliced so as to produce the electrodes and a second electrode material having a thickness greater than the average thickness of the electrodes.
  • the thickness of the fabricated second electrode material is more than 1 times the average thickness of the electrodes, so that at least one electrode can be obtained by slicing the second electrode material again as the first electrode material. This is because it can be manufactured. That is, in the above embodiment, the slicing step can be performed two or more times.
  • the method of slicing the first electrode material unevenly so as to fabricate electrodes with different thicknesses and the second electrode material is a method in which two electrodes with uniform thickness are fabricated.
  • the uneven slicing method requires that the thickness of the first electrode material be more than twice the average thickness of the electrode, whereas the even slicing method requires the thickness of the first electrode material This is because the thickness must be 2 n times the average thickness of the electrodes. n is an integer of 1 or more.
  • the first electrode material In the step of preparing the first electrode material, preparing the first electrode material having a thickness that is an integral multiple of three or more times the average thickness of the electrode; In the step of slicing the first electrode material, the first electrode material may be sliced so as to produce the electrodes and a second electrode material having a thickness greater than the average thickness of the electrodes.
  • the thickness of the manufactured second electrode material has a thickness that is an integral multiple of two or more times the thickness of the electrode. This is because two electrodes can be produced. That is, in the above embodiment, the slicing step can be performed two or more times.
  • the electrode can be produced without leaving the first electrode material.
  • the above-described configuration reduces the carbon fiber shavings generated by cutting to the first roller. And it is difficult to clog between the second roller and the first electrode material.
  • the step of feeding the first electrode material to the cutting tool it is preferable to feed the first electrode material to the cutting tool while restricting displacement of the first electrode material in the width direction by a guide.
  • the first electrode material can be easily moved substantially straight toward the gap between the first roller and the second roller, so it is easy to manufacture electrodes with small variations in thickness.
  • Batteries are redox flow batteries, fuel cells, lithium-ion batteries, and other batteries that use carbon materials as electrodes.
  • the following battery system will be described using a redox flow battery system as an example.
  • a redox flow battery system may be referred to as an RF battery system.
  • the same reference numerals in the drawings indicate the same names.
  • FIG. Electrode 1 is used in RF battery system 100, which will be described later with reference to FIG.
  • the electrode 1 comprises a sheet 2 made of nonwoven fabric containing a plurality of carbon fibers.
  • One of the features of the electrode 1 of this embodiment is to satisfy the following requirement (a1) and requirement (b1).
  • (a1) As shown in FIG. 1, the sheet 2 has a specific width Wa and a specific length La.
  • (b1) the plurality of carbon fibers have specific first carbon fibers;
  • the electrode 1 of this embodiment shown in FIG. 1 constitutes at least one of a positive electrode 4P and a negative electrode 4N, which will be described later with reference to FIG.
  • the electrode 1 contributes to the battery reaction in the RF battery system 100 shown in FIG.
  • the sheet 2 contains carbon fiber as a main component. Having carbon fiber as the main component means that the ratio of the weight of carbon fiber to the weight of sheet 2 is 50% or more.
  • the weight ratio of the carbon fibers to the weight of the sheet 2 is preferably 60% or more, particularly 70% or more.
  • the sheet 2 is a nonwoven fabric containing a plurality of carbon fibers. A nonwoven fabric is made by entangling independent carbon fibers. A plurality of carbon fibers form a three-dimensional network structure. Gaps are provided between the carbon fibers, that is, between the meshes.
  • the sheet 2 may contain at least one of binder, carbon particles, catalyst, hydrophilic material and hydrophobic material. The binder binds the carbon fibers together.
  • the carbon particles increase the surface area of sheet 2 . Catalysts promote cell reactions.
  • the sheet 2 has a first surface 21 and a second surface 22 facing each other in the direction along the thickness of the sheet 2, as shown in FIG. At least one of the first surface 21 and the second surface 22 is a cut surface.
  • the plurality of carbon fibers includes the first carbon fiber.
  • the first carbon fiber has at least one of a cut surface facing the first surface 21 and a cut surface facing the second surface 22 .
  • An example of the number of first carbon fibers is plural. That is, when the first surface 21 is a cut surface, a plurality of cut surfaces of the first carbon fibers are arranged side by side on the first surface 21 .
  • the second surface 22 is also a cut surface like the first surface 21 , the cut surfaces of the plurality of first carbon fibers are arranged on the second surface 22 like the first surface 21 .
  • the plurality of carbon fibers further includes a second carbon fiber.
  • Each of the second carbon fibers does not have both a cut surface facing the first surface 21 and a cut surface facing the second surface 22, unlike the first carbon fibers.
  • the second surface 22 is a non-cut surface
  • the second surface 22 faces the middle portion of the second carbon fiber in the longitudinal direction.
  • the end faces of the second carbon fibers are not aligned with the second surface 22 and are randomly arranged.
  • the cut surfaces of the plurality of first carbon fibers are not aligned on the second surface 22 .
  • planar shape The planar shape of the sheet 2 is rectangular as shown in FIG.
  • the planar shape is the shape when the first surface 21 or the second surface 22 is viewed from the thickness direction of the sheet 2 .
  • the term "rectangular shape" as used herein includes a rectangular shape and a square shape.
  • an example of the ratio of the long side to the short side of the sheet 2 is more than 1 and 5 or less. The above ratio may also be greater than 1 and no greater than 3, in particular greater than 1 and no greater than 2.
  • the width Wa of the sheet 2 is 1000 mm or less. Since the width Wa is 1000 mm or less, variations in the thickness of the sheet 2 are small.
  • the width Wa maintains the width Wb of the first electrode material 11 prepared in the electrode manufacturing method of the embodiment described later with reference to FIG. 7 and the like.
  • the sheet 2 with a width Wa of 1000 mm is produced using the first electrode material 11 with a width Wb of 1000 mm.
  • the width Wb is 1000 mm or less, it is easy to cut the same position in the thickness direction of the first electrode material 11 along the width direction of the first electrode material 11 in the electrode manufacturing method of the embodiment. Therefore, in the electrode manufacturing method of the embodiment, a sheet 2 having a small variation in thickness can be obtained.
  • the width Wa is also less than or equal to 750 mm, especially less than or equal to 500 mm.
  • An example of the lower limit of the width Wa is 200 mm.
  • a sheet 2 having a width Wa of 200 mm or more facilitates construction of high-output battery cells, cell stacks, and RF battery systems.
  • the width Wa is 200 mm or more and 1000 mm or less, further 300 mm or more and 750 mm or less, and particularly 350 mm or more and 500 mm or less.
  • the width Wa is the maximum width of the sheet 2 .
  • the length La of the sheet 2 is 2000 mm or less. Since the length La is 2000 mm or less, variations in the thickness of the sheet 2 are small. The length La is maintained at the length Lb of the first electrode material 11 shown in FIG.
  • the sheet 2 with a length La of 2000 mm is produced using the first electrode material 11 with a length Lb of 2000 mm.
  • the length Lb is 2000 mm or less, it is easy to cut the same position in the thickness direction of the first electrode material 11 along the length direction of the first electrode material 11 in the electrode manufacturing method of the embodiment. Therefore, in the electrode manufacturing method of the embodiment, a sheet 2 having a small variation in thickness can be obtained. Variation in the thickness of the sheet 2 tends to decrease as the length La decreases.
  • the length La is also less than or equal to 1500 mm, in particular less than or equal to 1000 mm.
  • An example of the lower limit of the length La is 500 mm.
  • a sheet 2 having a length La of 500 mm or more facilitates construction of high-output battery cells, cell stacks, and RF battery systems.
  • the length La is 500 mm or more and 2000 mm or less, further 650 mm or more and 1500 mm or less, and particularly 750 mm or more and 1000 mm or less.
  • the length La may be 500 mm or more and 1000 mm or less.
  • Length La is the maximum length of sheet 2 .
  • An example of the average thickness of the sheet 2 is 0.5 mm or more and 3 mm or less.
  • the sheet 2 having an average thickness of 0.5 mm or more facilitates construction of battery cells, cell stacks, and RF battery systems with excellent battery performance.
  • the sheet 2 having an average thickness of 0.5 mm or more has excellent mechanical strength.
  • a sheet 2 having an average thickness of 3 mm or less facilitates construction of thin battery cells and cell stacks. Therefore, the sheet 2 having an average thickness of 3 mm or less facilitates construction of a compact RF battery system.
  • An example of the average thickness of the sheet 2 is 0.5 mm or more and 2.5 mm or less, further 0.6 mm or more and 2.0 mm or less, and particularly 0.8 mm or more and 1.5 mm or less.
  • the average thickness of the sheet 2 is obtained as follows.
  • the number of thickness measurement points shall be 6 or more.
  • An example of the measurement points is at least the first intersection point P1 to the sixth intersection point P6, as shown in FIG. 4 or FIG.
  • the first intersection point P1 is the intersection point between the first virtual line V1 and the third virtual line V3.
  • the second intersection point P2 is the intersection point between the first virtual line V1 and the fourth virtual line V4.
  • a third intersection point P3 is an intersection point between the second virtual line V2 and the third virtual line V3.
  • a fourth intersection point P4 is an intersection point between the second virtual line V2 and the fourth virtual line V4.
  • the fifth intersection P5 is the intersection of the fifth virtual line V5 and the third virtual line V3.
  • the fifth intersection P5 is the intersection of the first virtual line V1 and the fifth virtual line V5.
  • the sixth intersection P6 is the intersection of the fifth virtual line V5 and the fourth virtual line V4.
  • the sixth intersection P6 is the intersection of the second virtual line V2 and the fifth virtual line V5.
  • the first imaginary line V1 is a straight line along the width direction of the sheet 2, and the distance from the first short side of the sheet 2 to the first imaginary line V1 is at least La ⁇ 0.1 times the length La ⁇ The straight line is 0.2 times or less.
  • the second imaginary line V2 is a straight line along the width direction of the sheet 2, and the distance from the second short side of the sheet 2 to the second imaginary line V2 is the length La ⁇ 0.1 times or more the length La ⁇ The straight line is 0.2 times or less.
  • the distance from the first short side to the first virtual line V1 is the same as the distance from the second short side to the second virtual line V2.
  • the third imaginary line V3 is a straight line along the length direction of the sheet 2, and the distance from the first long side of the sheet 2 to the third imaginary line V3 is not less than the width Wa ⁇ 0.1 times the width Wa ⁇ 0. .2 times or less.
  • the fourth imaginary line V4 is a straight line along the length direction of the sheet 2, and the distance from the second long side of the sheet 2 to the fourth imaginary line V4 is width Wa ⁇ 0.1 times or more width Wa ⁇ 0. .2 times or less.
  • the distance from the first long side to the third virtual line V3 is the same as the distance from the second long side to the fourth virtual line V4.
  • the fifth virtual line V5 is a straight line that divides evenly between the first virtual line V1 and the second virtual line V2.
  • the fifth virtual line V5 is a straight line that divides evenly between the third virtual line V3 and the fourth virtual line V4.
  • the above measurement points should be selected from the above range according to the width and length of the sheet 2 so that 6 or more measurement points can be collected.
  • a plurality of intersection points are arranged at equal intervals between the first intersection point P1 and the third intersection point P3 on the third virtual line V3, and the intersection between the second intersection point P2 and the fourth intersection point P4 on the fourth virtual line V4
  • a plurality of intersection points are arranged at regular intervals.
  • a plurality of intersection points are arranged at equal intervals between the first intersection point P1 and the second intersection point P2 on the first virtual line V1, and the intersection between the third intersection point P3 and the fourth intersection point P4 on the second virtual line V2.
  • a plurality of intersection points are arranged at regular intervals.
  • two or more virtual lines that equally divide the first virtual line V1 and the second virtual line V2 are taken.
  • two or more virtual lines that equally divide the third virtual line V3 and the fourth virtual line V4 are taken.
  • the thickness at each intersection can be obtained by measuring in accordance with JIS L 1096:2010 A method (JIS method). Specifically, using a commercially available thickness measuring device, the thickness of each intersection is measured under a constant time and a constant pressure. A contact-type digital synex gauge SMD-565J-L manufactured by Teclock is used as a thickness measuring device. The above time shall be 10 seconds. The above pressure is 0.7 kPa. Let the average value of all measured thicknesses be the average thickness of the sheet 2 .
  • a first example of variation in the thickness of the sheet 2 is 25% or less.
  • the first variation in thickness is obtained by "(standard deviation of thickness/average value of thickness) x 100".
  • the standard deviation of thickness is a value based on the average thickness of the sheet 2 and the measured value at each intersection as described above.
  • the average thickness is the average thickness of the sheet 2 described above. If the first variation in thickness is 25% or less, the battery performance of electrode 1 tends to be uniform over the entire area of electrode 1 .
  • the first variation in thickness is preferably as small as possible.
  • An example of the lower limit of the first variation in thickness is practically 2%.
  • the first thickness variation is 2% or more and 25% or less, further 5% or more and 20% or less, and particularly 6% or more and 15% or less.
  • the first variation in thickness may be between 2% and 15%.
  • a second example of variation in the thickness of the sheet 2 is 30% or less.
  • the second variation in thickness is obtained by " ⁇ (maximum thickness - minimum thickness)/average thickness ⁇ x 100".
  • the maximum thickness value is the maximum thickness among all the thicknesses at the intersections measured to obtain the average thickness of the sheet 2 described above.
  • the minimum thickness refers to the minimum thickness among all the thicknesses at the intersections. If the second thickness variation is 30% or less, the battery performance of the electrode 1 tends to be uniform over the entire area of the electrode 1 .
  • the second variation in thickness is preferably as small as possible.
  • An example of the lower limit of the second variation in thickness is practically 3%.
  • the second thickness variation is 3% or more and 30% or less, further 5% or more and 25% or less, and particularly 6% or more and 20% or less.
  • the first variation in basis weight of the sheet 2 is 25% or less.
  • the first variation in basis weight is obtained by "(standard deviation of basis weight/average value of basis weight) x 100".
  • the standard deviation of the basis weight is a value based on the average value of the basis weight and the measured value of the basis weight of each measurement piece.
  • the average weight per unit area is obtained as follows. Six or more measurement strips are cut out from one sheet 2. Each measurement piece has a square shape centered on each of the above intersections. The length of one side of each measuring piece shall be 30 mm.
  • the basis weight of each measurement piece is obtained by measuring the weight per unit area. Take the average value of all the basis weights obtained.
  • the conductivity of the electrode 1 and the fluidity of the electrolytic solution tend to be uniform over the entire area of the electrode 1 . It is preferable that the first variation in basis weight is as small as possible.
  • An example of the lower limit of the first variation in basis weight is practically 2%.
  • the first variation in basis weight is 2% or more and 25% or less, further 5% or more and 20% or less, and particularly 6% or more and 15% or less.
  • the first variation in basis weight may be 2% or more and 15% or less.
  • An example of a second variation in basis weight of the sheet 2 is 50 g/m 2 or less.
  • the second variation in basis weight is obtained by "maximum basis weight - minimum basis weight".
  • the maximum basis weight refers to the maximum basis weight among all the basis weights of the above-mentioned measurement pieces measured to obtain the above-mentioned average basis weight.
  • the minimum weight per unit area refers to the minimum weight per unit area among all the above-described measurement pieces. If the second variation in the basis weight is 50 g/m 2 or less, the conductivity of the electrode 1 and the flowability of the electrolytic solution tend to be uniform over the entire area of the electrode 1 .
  • the second variation in basis weight is preferably as small as possible.
  • An example of the lower limit of the second variation in basis weight is 2 g/m 2 .
  • the second variation of basis weight is 2 g/m 2 or more and 50 g/m 2 or less, further 4 g/m 2 or more and 35 g/m 2 or less, and particularly 5 g/m 2 or more and 20 g/m 2 or less.
  • the basis weight of the sheet 2 is 50 g/m 2 or more and 350 g/m 2 or less.
  • the basis weight of the sheet 2 is the basis weight of the entire sheet 2 .
  • the basis weight is obtained by measuring the weight per unit area.
  • the sheet 2 having a basis weight of 50 g/m 2 or more tends to increase the contact points between the carbon fibers, and thus tends to increase the conductivity.
  • the sheet 2 having a basis weight of 350 g/m 2 or less easily secures voids, and thus has excellent flowability of the electrolytic solution.
  • the basis weight of the sheet 2 is further 70 g/m 2 or more and 300 g/m 2 or less, particularly 80 g/m 2 or more and 250 g/m 2 or less.
  • porosity An example of the porosity of the sheet 2 is 60% or more and 99% or less. If the porosity of the sheet 2 is 60% or more, it has more voids than a sheet with a porosity of less than 60%. This sheet 2 is excellent in electrolyte solution flowability. If the porosity of the sheet 2 is 99% or less, the electrode 1 is excellent in battery reactivity.
  • the porosity of the sheet 2 is 60% or more and 95% or less, further 65% or more and 94% or less, and particularly 75% or more and 90% or less. The porosity is determined by "100 ⁇ [ ⁇ basis weight (g/m 2 )/average thickness (mm)/1000/density (g/cm 3 ) ⁇ 100]". Density is the density of carbon fibers. The density of carbon fibers will be described later.
  • the plurality of carbon fibers includes a carbon fiber 30 having a plurality of pleats 35 on its surface in this embodiment, as shown in FIG. FIG. 3 schematically shows the contour of the cross section of the carbon fiber 30.
  • the carbon fiber 30 has a corrugated uneven structure on its surface. Having a plurality of pleats 35 on the surface of the carbon fiber 30 facilitates increasing the surface area of the carbon fiber 30 .
  • the carbon fiber 30 having a large surface area tends to increase the reaction area in contact with the electrolytic solution. Therefore, the reactivity between the electrode 1 and the electrolyte is improved.
  • the cross-sectional shape of the carbon fibers 30 is an irregular cross-sectional shape.
  • At least one of the above-described first carbon fibers and the above-described second carbon fibers may have pleats 35 .
  • the plurality of carbon fibers may include carbon fibers that do not have pleats 35 . Also, not all of the plurality of carbon fibers may have the pleats 35 .
  • the cross-sectional shape of the carbon fibers without the pleats 35 may be, for example, circular or elliptical.
  • the circumference L1 is the circumference of the cross section of the carbon fiber 30 .
  • the perimeter L2 is the perimeter of the imaginary rectangle R circumscribing the cross section of the carbon fiber 30 .
  • the circumference ratio L1/L2 is more than 1, it is possible to secure a sufficient reaction area where the carbon fibers 30 and the electrolytic solution are in contact. Therefore, the reactivity between the electrode 1 and the electrolytic solution is improved.
  • the surface area of the carbon fiber 30 is proportional to the circumference L1.
  • An example of the circumference ratio L1/L2 is 1.1 or more.
  • the perimeter ratio L1/L2 When the perimeter ratio L1/L2 is large, the number of pleats 35 tends to increase. When the number of pleats 35 increases, the pleats 35 may stick together or the gap between the pleats 35 may narrow. In that case, it becomes difficult for the electrolytic solution to enter the gaps between the pleats 35 . Therefore, it may become difficult to obtain the effect of increasing the reaction area between the electrode 1 and the electrolytic solution.
  • One example of the upper limit of the circumference ratio L1/L2 is two. If the circumference ratio L1/L2 is 2 or less, it is easy to secure a sufficient gap between the pleats 35 . Therefore, it becomes easier for the electrolyte to enter the gaps between the pleats 35 .
  • An example of the circumference ratio L1/L2 is 1.8 or less, further 1.6 or less, and 1.4 or less.
  • the circumference ratio L1/L2 is more than 1 and 2 or less, more than 1.1 and 1.8 or less, more than 1.1 and 1.6 or less, and particularly more than 1.1 and 1.4 or less.
  • the circumference L1 is obtained as follows.
  • a cross section of the electrode 1 is observed with an optical microscope or a scanning electron microscope (SEM).
  • a cross section of the electrode 1 is a cross section cut along the thickness direction of the electrode 1 .
  • the outline of the cross section of the carbon fiber 30 is extracted from the cross section observation image obtained by this observation.
  • the total length of the extracted contour is measured by image analysis.
  • the method of obtaining the virtual rectangle R is as follows.
  • the contour of the cross section of the carbon fiber 30 is extracted from the cross section observed image.
  • a virtual rectangle R is defined by a first set of parallel lines and a second set of parallel lines.
  • the first pair of parallel lines is a pair of parallel lines having the minimum distance between the pair of parallel lines sandwiching the outline of the carbon fiber 30 .
  • the second pair of parallel lines is a pair of parallel lines that intersect the first pair of parallel lines and sandwich the outline of the carbon fiber 30, and the distance between the pair of parallel lines is the maximum distance. be.
  • the perimeter L2 is "the length of the short side of the virtual rectangle R a ⁇ 2+the length of the long side of the virtual rectangle R b ⁇ 2".
  • the circumference ratio L1/L2 is an average value measured as follows. A cross-sectional circumference L1 of each of the plurality of carbon fibers 30 is measured. A virtual rectangle R of the cross section of each of the plurality of carbon fibers 30 is obtained, and the circumference L2 of each virtual rectangle R is measured. Then, the circumference ratio L1/L2 of each carbon fiber 30 is calculated. Find the average value of all circumference ratios L1/L2.
  • the number of carbon fibers 30 to be measured is, for example, 3 or more, and further 5 or more.
  • Area ratio Sa/Sb An example of the area ratio Sa/Sb between the area Sa and the area Sb is 0.5 or more and 0.8 or less.
  • the area Sa is the cross-sectional area of the carbon fiber 30 .
  • the area Sb is the area of the imaginary rectangle R circumscribing the cross section of the carbon fiber 30 .
  • a cross section of the carbon fiber 30 is a cross section when the electrode 1 is cut along the thickness direction of the electrode 1 .
  • the area ratio Sa/Sb When the area ratio Sa/Sb is 0.5 or more, it is easy to sufficiently secure the strength of the carbon fibers 30 . Therefore, the strength of the electrode 1 is less likely to decrease.
  • the larger the area ratio Sa/Sb the narrower the gap between the folds 35 becomes.
  • the area ratio Sa/Sb is 0.8 or less, it is easy to sufficiently secure the gap between the pleats 35 . Therefore, it becomes difficult for the electrolyte to enter the gaps between the folds 35 . Therefore, the reaction area between the electrode 1 and the electrolytic solution can be ensured.
  • An example of the area ratio Sa/Sb is 0.55 or more and 0.75 or less, and particularly 0.55 or more and 0.7 or less.
  • An example of the area Sa is, for example, 20 ⁇ m 2 or more and 320 ⁇ m 2 or less, further 30 ⁇ m 2 or more and 300 ⁇ m 2 or less, and particularly 30 ⁇ m 2 or more and 90 ⁇ m 2 or less.
  • the area Sa can be measured by image analysis of the cross-sectional observation image described above.
  • the area ratio Sa/Sb is an average value measured as follows.
  • the cross-sectional area Sa of each of the plurality of carbon fibers 30 is measured.
  • the virtual rectangle R of the cross section of each of the plurality of carbon fibers 30 is obtained, and the area Sb of each virtual rectangle R is measured.
  • the area ratio Sa/Sb of each carbon fiber 30 is calculated. Find the average value of all the area ratios Sa/Sb.
  • the number of carbon fibers 30 to be measured is, for example, 3 or more, and further 5 or more.
  • An example of the long diameter of the carbon fibers 30 is 5 ⁇ m or more and 20 ⁇ m or less.
  • the major diameter of the carbon fiber 30 corresponds to the length b of the long side of the imaginary rectangle R.
  • the long diameter of the carbon fibers 30 is 5 ⁇ m or more, the strength of the carbon fibers 30 can be easily secured, and a decrease in the strength of the electrode 1 can be suppressed.
  • Carbon fibers 30 are thin because the major axis of carbon fibers 30 is 20 ⁇ m or less. Therefore, the carbon fibers 30 have flexibility. Therefore, the carbon fibers 30 are less likely to stick into a diaphragm 4M, which will be described later with reference to the upper diagram of FIG.
  • the long diameter of the carbon fibers 30 is 15 ⁇ m or less.
  • the short diameter of the carbon fiber 30 is equal to or less than the long diameter.
  • the minor axis of the carbon fiber 30 corresponds to the length a of the short side of the imaginary rectangle R.
  • An example of the short diameter of the carbon fibers 30 is 2 ⁇ m or more and 15 ⁇ m or less.
  • the short diameter and long diameter of the carbon fiber 30 are measured as follows. A virtual rectangle R of the cross section of each of the plurality of carbon fibers 30 is obtained. The short side length a and the long side length b of each virtual rectangle R are measured. Let the average value of the length a of all the short sides be the short diameter of the carbon fiber 30 . Let the average value of the length b of all the long sides be the length of the carbon fiber 30 .
  • the number of carbon fibers 30 to be measured is, for example, 3 or more, and further 5 or more.
  • the carbon fibers 30 are obtained by burning and carbonizing organic fibers.
  • the carbon fiber 30 having a plurality of pleats 35 can be produced by firing an organic fiber having a modified cross section with a plurality of pleats formed on the surface.
  • the organic fibers can change the cross-sectional shape of the fibers depending on the shape of the nozzle hole.
  • the density of carbon fibers is 1.5 g/cm 3 or more and 2.2 g/cm 3 or less. If the density of the carbon fiber is 1.5 g/cm 3 or more, the conductive component is large. The electrode 1 containing this carbon fiber facilitates construction of a battery cell with low internal resistance. If the density of the carbon fiber is 2.2 g/cm 3 or less, the stiffness of the carbon fiber is not too high. The electrode 1 containing this carbon fiber facilitates construction of a battery cell in which a diaphragm 4M, which will be described later with reference to the upper diagram of FIG. 10, is less likely to be damaged.
  • the density of the carbon fibers is further between 1.7 g/cm 3 and 2.1 g/cm 3 and especially between 1.8 g/cm 3 and 2.0 g/cm 3 .
  • the density of carbon fibers is obtained by measuring in accordance with JIS R 7603:1999 A method: liquid replacement method.
  • tensile strength An example of the tensile strength of the sheet 2 is 40 kPa or more and 300 kPa or less. A sheet 2 having a tensile strength of 40 kPa or more is excellent in strength. A sheet 2 having a tensile strength of 300 kPa or less tends to suppress damage to the diaphragm 4M. The tensile strength of the sheet 2 is further 60 kPa or more and 200 kPa or less, particularly 70 kPa or more and 150 kPa or less. The tensile strength of the sheet 2 is obtained by measuring in accordance with JIS L 1913:2010.
  • the electrode 1 of the present embodiment facilitates construction of battery cells, cell stacks, and RF battery systems with excellent battery performance. Specifically, the electrode 1 of the present embodiment facilitates construction of battery cells, cell stacks, and RF battery systems with high current efficiency and low cell resistivity.
  • the electrode manufacturing method of the present embodiment includes the following steps S1 and S2.
  • step S1 a sheet-like first electrode material 11 is prepared.
  • step S ⁇ b>2 the electrode 1 is produced by cutting the first electrode material 11 .
  • step S2 has a step S21 and a step S22.
  • a step S21 feeds the first electrode material 11 to the cutting tool 530 .
  • step S22 the cutting tool 530 slices the first electrode material 11 so that the thickness of the first electrode material 11 is reduced. Steps S1 and S2 will be described in order below.
  • the sheet-shaped first electrode material 11 to be prepared is composed of a nonwoven fabric containing a plurality of carbon fibers.
  • the cross-sectional shape, density, etc. of the carbon fibers contained in the first electrode material 11 are the same as the cross-sectional shape, density, etc. of the carbon fibers contained in the electrode 1 described above.
  • the first electrode material 11 is sliced so that the thickness of the first electrode material 11 is reduced in step S22, which will be described later.
  • the electrode 1 is produced by slicing the first electrode material 11 . That is, the first electrode material 11 and the electrode 1 differ only in thickness.
  • the planar shape, width Wb, and length Lb of the first electrode material 11 are maintained to the planar shape, width Wa, and length La of the electrode 1 .
  • the width Wa and the length La of the electrode 1 can be adjusted.
  • the planar shape, the numerical range of the width Wb, and the numerical range of the length Lb of the first electrode material 11 correspond to the planar shape of the sheet 2 constituting the electrode 1, the numerical range of the width Wa, and the numerical range of the length La. is similar to That is, the planar shape of the first electrode material 11 is rectangular.
  • the width Wb of the first electrode material 11 is 1000 mm or less.
  • the length Lb of the first electrode material 11 is 2000 mm or less.
  • the first electrode material 11 By preparing the first electrode material 11 having a width Wb of 1000 mm or less and a length Lb of 2000 mm or less, it is easy to manufacture the electrode 1 with a small first variation in thickness.
  • the second electrode 1 having a small variation in thickness is easily manufactured.
  • the electrode 1 having a small first variation in basis weight is easily manufactured.
  • the reason for this is that the width Wb of the first electrode material 11 is 1000 mm or less and the length Lb is 2000 mm or less, so that the first electrode material 11 extends along the width direction and the length direction of the first electrode material 11. This is because it is easy to cut at the same position in the thickness direction.
  • the thickness of the first electrode material 11 is not particularly limited and can be appropriately selected as long as it is more than 1 times the average thickness of the electrode 1 to be produced.
  • An example of the thickness of the first electrode material 11 is more than twice the average thickness of the electrode 1 , and an integer multiple of 3 times or more the average thickness of the electrode 1 .
  • the thickness of the first electrode material 11 is an integer multiple of 20 or less times the average thickness of the electrode 1, further an integer multiple of 15 or less times, and particularly an integer multiple of 10 or less times. That is, the thickness of the first electrode material 11 is an integer multiple of 3 to 20 times the average thickness of the electrode 1, further an integer multiple of 4 to 15 times, particularly 5 to 10 times. It is an integral multiple of the following.
  • the numerical ranges of the basis weight and the porosity of the first electrode material 11 are the same as the numerical ranges of the basis weight and the porosity of the sheet 2 described above.
  • a cutting machine 500 is used for cutting the first electrode material 11 .
  • the cutting machine 500 comprises a first roller 510 , a second roller 520 and a cutting tool 530 .
  • the first roller 510 and the second roller 520 are feed rollers that feed the first electrode material 11 toward the cutting tool 530 .
  • the first roller 510 and the second roller 520 are arranged vertically such that the peripheral surface of the first roller 510 and the peripheral surface of the second roller 520 face each other.
  • the rotation axis of the first roller 510 and the rotation axis of the second roller 520 are parallel.
  • the first roller 510 and the second roller 520 are drive rollers.
  • a drive roller is a roller driven by a drive source such as a motor.
  • the direction of rotation of the first roller 510 and the direction of rotation of the second roller 520 are opposite.
  • the gap between the first roller 510 and the second roller 520 is a gap that satisfies the following requirement (a3) and requirement (b3).
  • Requirement (a3) Pressure acts on the first electrode material 11 by sandwiching the first electrode material 11 from both sides in the thickness direction of the first electrode material 11 .
  • Requirement (b3) By the friction between the first roller 510 and the first electrode material 11 accompanying the rotation of the first roller 510 and the friction between the second roller 520 and the first electrode material 11 accompanying the rotation of the second roller 520 , the first electrode material 11 moves from upstream to downstream of the first roller 510 and the second roller 520 .
  • the cutting machine 500 of the present embodiment has a first roller 510 that can move at least one of the installation position of the first roller 510 and the installation position of the second roller 520 so as to increase or decrease the interval. It has a mechanism.
  • the cutting machine 500 is provided with a first mechanism so that the first electrode material 11 with various thicknesses can be sent to the cutting tool 530 by rotating the first roller 510 and the second roller 520 .
  • the width of the first roller 510 and the width of the second roller 520 are the same width.
  • the width of the first roller 510 is the length along the axis of rotation of the first roller 510 .
  • the width of the second roller 520 is the length along the axis of rotation of the second roller 520 .
  • Width Wr of first roller 510 will be described representatively with reference to FIG.
  • the width Wr of the first roller 510 is wider than the width Wb of the first electrode material 11 .
  • An example of the width Wr of the first roller 510 is 1200 mm or less. If the width Wr of the first roller 510 is 1200 mm or less, the width Wr of the first roller 510 is not too wide. Therefore, the interval is easily maintained uniform along the width direction. That is, the pressure applied to the first electrode material 11 by the first roller 510 and the second roller 520 can be made uniform in the width direction of the first electrode material 11 . Therefore, it is possible to manufacture the electrode 1 with small variations in thickness.
  • the cutting tool 530 is arranged downstream of the first roller 510 and the second roller 520 .
  • the cutting tool 530 is provided parallel to the rotation axis of the first roller 510 .
  • the cutting tool 530 is arranged so as to overlap the first roller 510 .
  • the cutting tool 530 may be arranged away from the first roller 510 without overlapping the first roller 510.
  • a knife can be used as the cutting tool 530 .
  • the knife may be provided to travel in one direction along the rotation axis of the first roller 510, or may be provided to reciprocate along the direction parallel to the rotation axis of the first roller 510. good too.
  • a ring-shaped band knife can be suitably used as the knife. This band knife runs in one direction in the longitudinal direction of the band knife.
  • the cutting machine 500 of this embodiment includes a second mechanism capable of vertically moving the installation position of the cutting tool 530 .
  • the installation position of the cutting tool 530 can be a position that satisfies the following requirement (a4) or requirement (b4).
  • (a4) The thickness of the first electrode material 11 is evenly sliced.
  • (b4) The thickness of the first electrode material 11 is sliced unevenly.
  • the electrode 1 can be fabricated with the same thickness as For example, if the thickness of the first electrode material 11 is more than twice the average thickness of the electrode 1 and the installation position of the cutting tool 530 satisfies the above requirement (b4), as shown in FIG.
  • the electrode 1 and the second electrode material 12 having an average thickness greater than that of the electrode 1 can be produced.
  • the second electrode material 12 is sliced again as the first electrode material 11 .
  • the installation position of the cutting tool 530 can be set to a position that satisfies the following requirement (a5) or requirement (b5) by controlling the second mechanism. can. (a5)
  • the electrode 1 flows below the position where the cutting tool 530 is installed, and the second electrode material 12 flows above the position where the cutting tool 530 is installed.
  • the electrode 1 flows above the position where the cutting tool 530 is installed, and the second electrode material 12 flows below the position where the cutting tool 530 is installed.
  • the installation position of the cutting tool 530 that satisfies the requirement (a5) is more preferable than the position that satisfies the requirement (b5).
  • the carbon fiber shavings generated by cutting are more likely to be between the first roller 510 and the first electrode material 11 than when the position satisfies the above requirement (b5). This is because clogging is less likely to occur between the second roller 520 and the first electrode material 11 .
  • the cutting machine 500 may further include a table 540 shown in FIG. 8 and a pair of guides 550 shown in FIG. FIG. 6 omits the table and the pair of guides for convenience of explanation.
  • FIG. 7 omits the table for convenience of explanation.
  • FIG. 8 omits one guide for convenience of explanation.
  • the table 540 is arranged upstream of the first roller 510 and the second roller 520 .
  • the first electrode material 11 moves on the table 540 toward the first roller 510 and the second roller 520 .
  • the table 540 includes a plurality of rollers.
  • a plurality of rollers are arranged so that the rotation axes of the rollers are parallel to each other.
  • the rotation axis of each roller is parallel to the rotation axis of the first roller 510 .
  • a plurality of rollers are driven rollers.
  • the driven roller is a roller that rotates due to friction with the first electrode material 11 but is not driven by a driving source such as a motor.
  • the plurality of rollers may be drive rollers.
  • a drive roller is a roller rotated by a drive source such as a motor. Since the table 540 has a plurality of rollers, the first electrode material 11 can easily move on the table 540 toward the first roller 510 and the second roller 520 .
  • the pair of guides 550 regulates the displacement of the first electrode material 11 in the width direction.
  • a pair of guides 550 can feed the first electrode material 11 straight toward the first roller 510 and the second roller 520 .
  • Each of the pair of guides 550 is arranged on each side of the table 540 in the width direction.
  • a ridge extending along the direction perpendicular to the width direction of the table 540 can be preferably used.
  • a pair of guides 550 are arranged parallel to each other.
  • a pair of guides 550 are arranged along a direction perpendicular to the rotation axis of the first roller 510 .
  • the gap between the pair of guides 550 is slightly larger than the width Wb of the first electrode material 11 .
  • Step S21 the first electrode material 11 is sandwiched between the first roller 510 and the second roller 520, and the first electrode material 11 is fed to the cutting tool 530 by rotating the first roller 510 and the second roller 520. be done.
  • the first electrode material 11 is not pulled from the downstream side of the first roller 510 and the second roller 520 . That is, the first electrode material 11 is sent to the cutting tool 530 without substantially acting on the first electrode material 11 in tension along the traveling direction of the first electrode material 11 .
  • substantially no tension is applied to the first electrode material 11 in the traveling direction of the first electrode material 11 .
  • Step S22 In step S ⁇ b>22 , the first electrode material 11 is sliced without substantially acting on the first electrode material 11 with tension along the traveling direction of the first electrode material 11 . Therefore, the same position in the thickness direction of the first electrode material 11 is easily cut along the width direction and the length direction of the first electrode material 11 by the cutting tool 530 .
  • the electrode 1 having an average thickness of 0.5 mm or more and 3 mm or less is preferably manufactured.
  • the first electrode material 11 may be sliced so that the electrode 1 and the second electrode material 12 are produced by slicing the first electrode material 11 . Moreover, it is preferable to slice the first electrode material 11 so that the electrode 1 flows below the installation position of the cutting tool 530 and the second electrode material 12 flows above the installation position.
  • the second electrode material 12 is sliced again by the cutting machine 500 as the first electrode material 11 . That is, step S21 and step S22 are repeated. Although it depends on the thickness of the first electrode material 11 to be prepared, two electrodes 1 are produced by slicing the second electrode material 12, and one electrode 1 is thicker than the electrode 1. In other cases, a single electrode 1 and a third electrode material thicker than the electrode 1 are produced. Steps S21 and S22 are repeated until two electrodes 1 or one electrode 1 and the remainder portion are fabricated by one step S2. That is, when the third electrode material is produced, the third electrode material is sliced again by the cutting machine 500 as the first electrode material 11 .
  • the first step S22 to the last step before the final step. Up to S22, the first electrode material 11 is sliced unevenly. In the final step S22, the first electrode material 11 is evenly sliced.
  • the electrode 1 produced by slicing the first electrode material 11 is a sheet 2 having a first surface 21 which is a cut surface and a second surface 22 which is a non-cut surface.
  • the multiple carbon fibers forming the sheet 2 include the first carbon fibers described above and the multiple second carbon fibers described above.
  • the first carbon fibers have cut surfaces facing the first surface 21 as described above.
  • the first carbon fibers do not have a cut surface facing the second surface 22 .
  • a plurality of cut surfaces of the first carbon fibers are arranged side by side on the first surface 21 .
  • the second surface 22 faces the middle portion of the second carbon fiber in the longitudinal direction.
  • the electrode 1 When one electrode 1 and one third electrode material are produced by slicing the second electrode material 12, the electrode 1 has a first surface 21 as a cut surface and a second surface 22 as a cut surface.
  • one electrode 1 has a first surface 21 which is a cut surface and a non-cut surface.
  • Another electrode 1 is a sheet 2 having a first surface 21 that is a cut surface and a second surface 22 that is a cut surface.
  • the electrode manufacturing method of this embodiment can manufacture the electrode 1 described above.
  • the width of the first electrode material 11 to be sliced is 1000 mm or less, and the length of the first electrode material 11 is 2000 mm or less. That is, the width of the first electrode material 11 is narrow and the length of the first electrode material 11 is short.
  • the first electrode material 11 is sent to the cutting tool 530 by the rotation of the first roller 510 and the second roller 520 that sandwich the first electrode material 11 . That is, in the electrode manufacturing method of the present embodiment, the first electrode material 11 is sliced without substantially applying tension to the first electrode material 11 . Therefore, in the electrode manufacturing method of the present embodiment, it is easy to cut the same position in the thickness direction of the first electrode material 11 along the width direction and the length direction of the first electrode material 11 .
  • the RF battery system 100 includes battery cells 4 .
  • the battery cell 4 has a diaphragm 4M, a positive electrode 4P and a negative electrode 4N.
  • the diaphragm 4M is arranged between the positive electrode 4P and the negative electrode 4N.
  • At least one of the positive electrode 4P and the negative electrode 4N is composed of the electrode 1 described above.
  • the RF battery system 100 shown in FIG. 9 charges and stores the power generated by the power generation unit 310 , discharges the stored power, and supplies it to the load 330 .
  • RF battery system 100 is typically connected between power generation section 310 and load 330 via AC/DC converter 300 and transformer equipment 320 .
  • An example of the power generation unit 310 is a solar power generation device, a wind power generation device, or other general power plants.
  • An example of the load 330 is a power consumer or the like.
  • a solid line arrow extending from the substation equipment 320 toward the AC/DC converter 300 means charging.
  • a dashed arrow extending from the AC/DC converter 300 toward the substation 320 means discharge.
  • the RF battery system 100 uses a positive electrolyte and a negative electrolyte.
  • the positive electrode electrolyte and the negative electrode electrolyte contain, as active materials, metal ions whose valences change due to oxidation-reduction. Charging and discharging of the RF battery system 100 is performed using the difference between the oxidation-reduction potential of ions contained in the positive electrode electrolyte and the oxidation-reduction potential of ions contained in the negative electrode electrolyte. Examples of applications for the RF battery system 100 include load leveling, voltage sag compensation, emergency power, or output smoothing of natural energy sources such as solar or wind power.
  • a battery cell 4 provided in the RF battery system 100 is separated into a positive electrode cell and a negative electrode cell by a diaphragm 4M.
  • the diaphragm 4M is an ion exchange membrane that is impermeable to electrons but permeable to hydrogen ions, for example.
  • the positive cell incorporates a positive electrode 4P.
  • the negative cell incorporates a negative electrode 4N.
  • An electrolytic solution is circulated in the battery cells 4 by a circulation mechanism 6, which will be described later.
  • the circulation mechanism 6 includes a positive electrode circulation mechanism 6P and a negative electrode circulation mechanism 6N.
  • the positive electrode circulation mechanism 6P circulates the positive electrode electrolyte to the positive electrode cells.
  • the negative electrode circulation mechanism 6N circulates the negative electrode electrolyte to the negative electrode cells.
  • Battery cells 4 are usually formed inside a structure called a cell stack 200 as shown in FIGS. 9 and 10 .
  • the cell stack 200 includes a substack 201 , two end plates 220 and a tightening mechanism 230 .
  • the cell stack 200 exemplifies a form including a plurality of sub-stacks 201 in the lower diagram of FIG. 10 .
  • Each sub-stack 201 comprises a laminate and two feeding/discharging plates 210, as shown in the lower diagram of FIG.
  • the laminate is constructed by stacking a plurality of cell frames 5, positive electrodes 4P, diaphragms 4M, and negative electrodes 4N in this order.
  • the supply/discharge plates 210 are arranged at both ends of the laminate, as shown in the lower diagram of FIG.
  • a supply pipe 63 and a discharge pipe 65 of the positive electrode circulation mechanism 6P and a supply pipe 64 and a discharge pipe 66 of the negative electrode circulation mechanism 6N, which will be described later, are connected to the supply/discharge plate 210 .
  • the two end plates 220 sandwich the plurality of substacks 201 from the outside of the substacks 201 at both ends.
  • a tightening mechanism 230 tightens both end plates 220 .
  • the cell frame 5 includes bipolar plates 51 and a frame 52 .
  • the frame 52 surrounds the outer peripheral edge of the bipolar plate 51 .
  • One battery cell 4 is formed between the bipolar plates 51 of adjacent cell frames 5 .
  • a positive electrode 4P is arranged on one side of the bipolar plate 51 so as to face each other.
  • a negative electrode 4N is arranged on the other surface of the bipolar plate 51 so as to face each other.
  • the frame body 52 is formed with liquid supply manifolds 53 and 54, liquid supply slits 53s and 54s, liquid discharge manifolds 55 and 56, and liquid discharge slits 55s and 56s, which will be described later.
  • An annular seal member 57 is arranged in an annular seal groove between the frames 52 .
  • the positive electrode circulation mechanism 6 ⁇ /b>P includes a positive electrode electrolyte tank 61 , a supply pipe 63 , a discharge pipe 65 and a pump 67 .
  • a positive electrode electrolyte is stored in the positive electrode electrolyte tank 61 .
  • the positive electrode electrolyte flows through the supply pipe 63 and the discharge pipe 65 .
  • the supply pipe 63 connects the positive electrode electrolyte tank 61 and the positive electrode cell.
  • the discharge pipe 65 connects the positive electrode cell and the positive electrode electrolyte tank 61 .
  • the pump 67 pressure-feeds the positive electrode electrolyte in the positive electrode electrolyte tank 61 .
  • the pump 67 is provided in the middle of the supply pipe 63 .
  • the negative electrode circulation mechanism 6N includes a negative electrode electrolyte tank 62, a supply pipe 64, a discharge pipe 66, and a pump 68.
  • a negative electrode electrolyte is stored in the negative electrode electrolyte tank 62 .
  • a negative electrode electrolyte is circulated through the supply pipe 64 and the discharge pipe 66 .
  • a supply pipe 64 connects the negative electrode electrolyte tank 62 and the negative electrode cell.
  • the discharge pipe 66 connects the negative electrode cell and the negative electrode electrolyte tank 62 .
  • a pump 68 pumps the negative electrode electrolyte in the negative electrode electrolyte tank 62 .
  • a pump 68 is provided in the middle of the supply pipe 64 .
  • the flow of the positive electrode electrolyte and the negative electrode electrolyte during charge/discharge operation is as follows.
  • the positive electrode electrolyte is supplied from the positive electrode electrolyte tank 61 through the supply pipe 63 to the positive electrode cell by the pump 67 .
  • the positive electrode electrolyte flows from the liquid supply manifold 53 through the liquid supply slit 53s and is supplied to the positive electrode 4P.
  • the positive electrode electrolyte supplied to the positive electrode 4P flows from the lower side to the upper side of the positive electrode 4P as indicated by the arrows in the upper diagram of FIG.
  • the positive electrode electrolyte that has flowed through the positive electrode 4 ⁇ /b>P flows through the drainage slit 55 s and is discharged to the drainage manifold 55 .
  • the positive electrode electrolyte flows from the positive electrode cell through the discharge pipe 65 and is discharged to the positive electrode electrolyte tank 61 .
  • a pump 68 supplies the negative electrode electrolyte from the negative electrode electrolyte tank 62 through the supply pipe 64 to the negative electrode cell.
  • the negative electrode electrolyte flows from the liquid supply manifold 54 through the liquid supply slit 54s and is supplied to the negative electrode 4N.
  • the negative electrode electrolyte supplied to the negative electrode 4N flows from the lower side to the upper side of the negative electrode 4N as indicated by the arrows in the upper diagram of FIG.
  • the negative electrode electrolyte that has flowed through the negative electrode 4N flows through the drain slit 56s and is discharged to the drain manifold 56.
  • the negative electrode electrolyte flows from the negative electrode cell through the discharge pipe 66 and is discharged to the negative electrode electrolyte tank 62 .
  • the positive electrode electrolyte is circulated to the positive electrode cell, and the negative electrode electrolyte is circulated to the negative electrode cell.
  • the pumps 67 and 68 are stopped during standby when charging and discharging are not performed. That is, the positive electrolyte and the negative electrolyte are not circulated.
  • the positive electrode active material contained in the positive electrode electrolyte includes one or more selected from the group consisting of manganese ions, vanadium ions, iron ions, polyacids, quinone derivatives, and amines.
  • the negative electrode active material contained in the negative electrode electrolyte includes one or more selected from the group consisting of titanium ions, vanadium ions, chromium ions, polyacids, quinone derivatives, and amines.
  • RF battery system 100 may be, for example, an all-vanadium RF battery system in which each of the positive and negative electrode active materials is vanadium ions.
  • Solvents for the positive electrode electrolyte and the negative electrode electrolyte include aqueous solutions containing one or more acids or acid salts selected from the group consisting of sulfuric acid, phosphoric acid, nitric acid, and hydrochloric acid.
  • Sample no. 1 to sample no. 3 electrode similarly to the electrode manufacturing method of the above-described embodiment, the step S1 of preparing a sheet-like first electrode material and the step S2 of cutting the first electrode material to prepare an electrode are performed in this order. manufactured by
  • the first electrode material of each sample consisted of a nonwoven fabric containing a plurality of carbon fibers.
  • the plurality of carbon fibers includes carbon fibers having a plurality of pleats on their surfaces.
  • the planar shape of each first electrode material is rectangular.
  • the width and length of each first electrode material are as shown in Table 1.
  • Step S2 In step S2, a step S21 of sending the first electrode material to the cutting tool and a step S22 of slicing the first electrode material so that the thickness of the first electrode material is reduced by the cutting tool were sequentially performed.
  • step S2 the cutting machine 500 described above with reference to FIGS. 6 to 8 was used.
  • the width of the first roller 510 and the width of the second roller 520 were greater than the width of each first electrode material.
  • a knife was used as the cutting tool 530 .
  • the installation position of the cutting tool 530 was a position that satisfies both the following requirement (a6) and requirement (b6).
  • An electrode and a second electrode material having a thickness greater than the average thickness of the electrode are produced by slicing the first electrode material unevenly.
  • the electrode flows below the position where the cutting tool 530 is installed, and the second electrode material flows above the position where the cutting tool 530 is installed.
  • the average electrode thickness of each sample was varied.
  • the spacing between the pair of guides 550 was slightly larger than the width of each first electrode material.
  • each first electrode material was sent to the cutting tool 530 by rotating the first roller 510 and the second roller 520 that sandwich the first electrode material.
  • step S22 an electrode and a second electrode material having a thickness greater than the average thickness of the electrode were produced. Further, in step S22, the produced electrode flowed below the position where the cutting tool 530 was installed, and the produced second electrode material flowed above the position where the cutting tool 530 was installed. In this example, the number of times that step S21 and step S22 were performed was five. That is, the number of electrodes produced from one first electrode material was six. Step S22 was performed so that the average thickness of the six electrodes was equal. The thickness of the first electrode material of each sample was such that the step S21 and step S22 were performed five times, and the average thickness of each electrode was the value shown in Table 2.
  • Each electrode has a first surface and a second surface facing each other in the thickness direction.
  • the first surface is the cut surface and the second surface is the non-cut surface.
  • both the first surface and the second surface are cut surfaces.
  • Each electrode was cut along the thickness direction of the electrode. The vicinity of the first surface in the cross section of each electrode was observed with an SEM.
  • Each electrode was found to include a first carbon fiber having a cut surface facing the first face.
  • the width and length of the electrode of each prepared sample were the same as the first electrode material of each prepared sample. Average thickness of electrode of each sample (mm), first variation in thickness (%), second variation in thickness (%), first variation in basis weight (%), second basis weight variation (g/m 2 ), basis weight (g/m 2 ), porosity (%), and density (g/cm 3 ) of the carbon fibers that make up the electrode of each sample were determined as described above. I asked. Those results are shown in Table 2. The results shown in Table 2 are the values for one of the six electrodes fabricated for each sample. Also, the tensile strength of the electrode of each sample is determined as described above.
  • the tensile strength of the electrode of each sample satisfies the range of 40 kPa or more and 300 kPa or less. This tensile strength result is also the value for one of the six electrodes fabricated for each sample.
  • Sample no. 101 electrode and sample no. 102 electrode is sample No. 1 to sample no. It was manufactured by a manufacturing method different from the manufacturing method of the electrode of No. 3. Sample no. 101 electrode and sample no. 102, the size of the electrode material to be prepared and the cutting method of the electrode material are the same as those of sample No. 102; 1 to sample no. 3 electrode manufacturing method. Sample no. 101 electrode and sample no. The electrode No. 102 was manufactured by sequentially performing a step S100 of preparing a roll-shaped electrode material and a step S200 of cutting the electrode material to prepare an electrode.
  • the electrode material of each sample is composed of a nonwoven fabric containing a plurality of carbon fibers. Table 1 shows the width and length of each electrode material.
  • step S200 the thickness of the electrode material is evenly sliced by a cutting tool.
  • step S200 a first cutting machine different from the cutting machine 500 described above was used.
  • the first cutting machine is equipped with a supply reel, an upper roller, a lower roller, a cutting tool and two take-up reels.
  • a roll-shaped electrode material is installed on the supply reel.
  • the supply reel is the driven reel.
  • the upper roller and the lower roller are mainly not feed rollers for feeding the electrode material to the cutting tool, but guide rollers for regulating vertical displacement of the electrode material. That is, the upper and lower rollers are driven rollers rather than driven rollers.
  • the width of the upper roller and the width of the lower roller were greater than the width of each electrode material.
  • a knife was used as the cutting tool.
  • the cutting tool was installed at a position where the thickness of the electrode material could be evenly sliced.
  • Each take-up reel winds up each of the two long sheets produced.
  • Each take-up reel is a drive reel.
  • Each take-up reel winds up each of the two long sheets, thereby rewinding the electrode material set on the supply reel.
  • the electrode material is sliced in a state in which tension is applied to the electrode material along the traveling direction of the electrode material by winding on each take-up reel.
  • the number of times the step S200 was performed is a plurality of times.
  • Each long sheet wound into a roll by each take-up reel is placed on the delivery reel, and sliced into a uniform thickness by the cutting tool as described above.
  • the number of long sheets produced from one electrode material was four or more.
  • the thickness of the electrode material of each sample was such that the average thickness of each long sheet was the value shown in Table 2 after performing step S200 a plurality of times.
  • An electrode for each sample is obtained by cutting the long sheet of each sample into a predetermined length.
  • the width and length of the long sheet of each sample prepared were the same as the electrode material of each prepared sample. Average thickness of long sheet of each sample (mm), first variation in thickness (%), second variation in thickness (%), first variation in basis weight (%), basis weight Second variation (g/m 2 ), basis weight (g/m 2 ), porosity (%), and carbon fiber density (g/cm 3 ) constituting the long sheet of each sample, Sample no. It was obtained in the same manner as for 1. Those results are shown in Table 2. The results shown in Table 2 are the values for one long sheet out of four or more long sheets produced.
  • a single cell battery was produced using the electrode of each sample, and the current efficiency and cell resistivity were measured.
  • a single cell battery is a battery having one positive electrode, one diaphragm, and one negative electrode.
  • a single cell battery was constructed by stacking a first cell frame, a positive electrode, a diaphragm, a negative electrode, and a second cell frame in this order. The diaphragm is sandwiched between the positive electrode and the negative electrode.
  • the first cell frame is arranged such that the bipolar plate provided in the first cell frame and the positive electrode are in contact with each other.
  • the second cell frame is arranged such that the bipolar plate provided in the second cell frame and the negative electrode are in contact with each other.
  • sample no. 1 was applied to the positive electrode and the negative electrode. 1 to sample no. 3, sample no. 101, and sample no. 102 individual electrodes were used. The width and length of the electrodes of each sample were the same.
  • the long sheets of sample No. 101 and sample No. 102 were cut into sample No. 101 and sample No. 102.
  • sample no. 2 sample no. 101 and sample No. 102 had a width of 350 mm and a length of 500 mm.
  • a vanadium sulfate solution containing vanadium ions as an active material was used for each of the positive electrode electrolyte and the negative electrode electrolyte.
  • the battery cell of each sample was charged and discharged at a constant current density of 90 mA/cm 2 .
  • multiple cycles of charging and discharging were performed.
  • charging was switched to discharging when a preset switching voltage was reached, and discharging was switched to charging when a preset switching voltage was reached.
  • the switching voltage from charge to discharge was set to 1.62V.
  • the switching voltage from discharging to charging was set to 1.0V.
  • the current efficiency (%) and cell resistivity ( ⁇ cm 2 ) of each sample were determined. The current efficiency was the average value calculated by (total discharge time/total charge time) ⁇ 100 for each cycle.
  • the cell resistivity was calculated by ⁇ (difference between average voltage during charge and average voltage during discharge)/(average current/2) ⁇ effective area of electrode.
  • the effective area was 320 mm ⁇ 470 mm.
  • the average voltage during charging and the average voltage during discharging were the average voltages in an arbitrary one cycle among a plurality of cycles. Those results are shown in Table 3.
  • Each of the 3 electrodes was sample no. 101 and sample no. The first variation in thickness and the second variation in thickness were small compared to each of the 102 elongated sheets.
  • Each of the 3 electrodes was sample no. 101 and sample no. The first variation in the basis weight and the second variation in the basis weight were smaller than each of the 102 long sheets.
  • Each of the single cell batteries using No. 3 electrodes was sample no. 101 and sample no. Compared to each of the single cell batteries using the 102 long sheets, the current efficiency was high and the cell resistivity was low. From this result, sample no. 1 to sample no.
  • Each of the 3 electrodes was sample no. 101 and sample no. It was found that a battery cell having excellent battery performance can be constructed compared to each of the 102 long sheets.
  • sample No. Sample No. 101 was prepared in the same manner. 200 long sheets are produced. That is, the electrode material having a width of 1000 mm or less is evenly sliced in a state in which tension is applied along the traveling direction of the electrode material. Sample no. 200 long sheet thickness first variation (%), thickness second variation (%), basis weight first variation (%), and basis weight second variation (g/ m 2 ), sample no. It is obtained in the same manner as the long sheet of 101. As a result, sample no. The first variation in thickness, the second variation in thickness, the first variation in basis weight, and the second variation in basis weight of the long sheet of sample No. 200 were obtained.
  • sample no. 200 single cell battery is sample no. 1 to sample no. It is considered that the battery performance is inferior to that of the single cell battery of No. 3.

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PCT/JP2021/033821 2021-09-14 2021-09-14 電極、電池セル、セルスタック、電池システム、及び電極の製造方法 Ceased WO2023042280A1 (ja)

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