WO2022153615A1 - Battery cell, cell stack, and redox flow battery system - Google Patents

Battery cell, cell stack, and redox flow battery system Download PDF

Info

Publication number
WO2022153615A1
WO2022153615A1 PCT/JP2021/035847 JP2021035847W WO2022153615A1 WO 2022153615 A1 WO2022153615 A1 WO 2022153615A1 JP 2021035847 W JP2021035847 W JP 2021035847W WO 2022153615 A1 WO2022153615 A1 WO 2022153615A1
Authority
WO
WIPO (PCT)
Prior art keywords
diaphragm
less
fiber
positive electrode
battery cell
Prior art date
Application number
PCT/JP2021/035847
Other languages
French (fr)
Japanese (ja)
Inventor
吉恭 川越
正幸 大矢
清晃 森内
Original Assignee
住友電気工業株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 住友電気工業株式会社 filed Critical 住友電気工業株式会社
Publication of WO2022153615A1 publication Critical patent/WO2022153615A1/en

Links

Images

Classifications

    • 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
    • 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
    • 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

Definitions

  • the present disclosure relates to battery cells, cell stacks, and redox flow battery systems.
  • This application claims priority based on Japanese Patent Application No. 2021-002853 of the Japanese application dated January 12, 2021, and incorporates all the contents described in the Japanese application.
  • the battery element of the redox flow battery of Patent Document 1 includes a positive electrode, a negative electrode, an ion exchange membrane, and a porous sheet material.
  • the ion exchange membrane is arranged between the positive electrode and the negative electrode.
  • the porous sheet material is provided on each surface of the ion exchange membrane facing the positive electrode and the surface facing the negative electrode.
  • the positive electrode and the negative electrode are made of a non-woven fabric made of carbon fiber.
  • the porous sheet material is composed of an organic material.
  • the battery cell of the present disclosure is a battery cell including a positive electrode, a negative electrode, and a diaphragm, and is arranged between the positive electrode and the diaphragm and at least one of the negative electrode and the diaphragm.
  • the first layer is a first fiber aggregate having a plurality of first fibers made of an insulating material, and the average diameter of the plurality of first fibers is 2 ⁇ m or more and 50 ⁇ m or less.
  • the void ratio of the first fiber aggregate is 20% or more and 99% or less.
  • the cell stack of the present disclosure includes a plurality of battery cells, and at least one of the plurality of battery cells is the battery cell of the present disclosure.
  • the redox flow battery system of the present disclosure includes the battery cells of the present disclosure or the cell stack of the present disclosure.
  • FIG. 1 is a schematic configuration diagram of a redox flow battery system according to an embodiment.
  • FIG. 2 is a schematic configuration diagram of a cell stack provided in the redox flow battery system according to the embodiment.
  • FIG. 3 is an enlarged view showing an enlarged surface of the first layer provided in the redox flow battery system according to the embodiment.
  • FIG. 4 is an enlarged view showing an enlarged surface of an electrode provided in the redox flow battery system according to the embodiment.
  • FIG. 5 is an explanatory diagram showing measurement points for measuring the thickness of the first layer provided in the redox flow battery system according to the embodiment.
  • the porous sheet material protects the ion exchange membrane by being provided between the electrode and the ion exchange membrane.
  • the protection of the ion exchange membrane prevents damage to the ion exchange membrane due to contact between the electrode and the ion exchange membrane. Specifically, it prevents the fibers of the electrode from sticking into the ion exchange membrane and cracking the ion exchange membrane.
  • the porous sheet material may inhibit the diffusion of the electrolytic solution. If the diffusion of the electrolytic solution is inhibited, the reaction resistivity of the battery cell may increase.
  • One of the purposes of the present disclosure is to provide a battery cell, a cell stack, and a redox flow battery system that can easily achieve both improvement in current efficiency and reduction in reaction resistivity.
  • the battery cell, cell stack, and redox flow battery system of the present disclosure can easily achieve both improvement in current efficiency and reduction in reaction resistivity.
  • the battery cell according to one aspect of the present disclosure is a battery cell including a positive electrode, a negative electrode, and a diaphragm, and is between the positive electrode and the diaphragm and between the negative electrode and the diaphragm. It comprises a first layer arranged between at least one of the first layers, which is a first fiber assembly having a plurality of first fibers made of an insulating material, and is an average of the plurality of first fibers.
  • the diameter is 2 ⁇ m or more and 50 ⁇ m or less, and the void ratio of the first fiber aggregate is 20% or more and 99% or less.
  • the diaphragm In a battery cell in which the first layer is not arranged, the diaphragm is easily damaged especially when the battery cell is assembled.
  • the battery cell is usually assembled by stacking the cell frame, the positive electrode, the diaphragm, and the negative electrode in this order. During the flat stacking, the electrodes and the diaphragm may rub against each other when aligning the members. Excessive rubbing between the electrodes and the diaphragm makes the diaphragm more susceptible to damage.
  • the contact between the electrode and the diaphragm is easily suppressed by the first layer arranged between at least one of the positive electrode and the negative electrode and the diaphragm.
  • the first layer which is composed of the first fiber aggregate having a porosity of 99% or less, contributes to maintaining the distance between the electrode and the diaphragm.
  • the first layer composed of the first fiber aggregate having a porosity of 99% or less has the second fiber even if the electrode is composed of the second fiber aggregate having a plurality of second fibers. It is easy to suppress the penetration of the diaphragm through the voids of the first layer. Therefore, the battery cell of the present disclosure can easily suppress damage to the diaphragm due to contact between the electrode and the diaphragm.
  • the first layer is composed of a first fiber aggregate having a plurality of first fibers.
  • the first fiber having an average diameter of 2 ⁇ m or more is unlikely to pierce the septum.
  • the first fiber having an average diameter of 50 ⁇ m or less is less likely to be caught in the diaphragm. Therefore, the battery cell of the present disclosure can easily suppress damage to the diaphragm due to contact between the first layer and the diaphragm.
  • the battery cell of the present disclosure tends to improve the current efficiency.
  • the first layer in which the porosity of the first fiber aggregate satisfies 20% or more easily diffuses the electrolytic solution. Therefore, the battery cell of the present disclosure tends to reduce the reaction resistivity.
  • the basis weight of the first fiber aggregate is 5 g / m 2 or more and 100 g / m 2 or less.
  • the first fiber aggregate having a grain size of 5 g / m 2 or more can easily suppress damage to the diaphragm due to contact between at least one of the positive electrode and the negative electrode and the diaphragm.
  • the first fiber aggregate having a basis weight of 100 g / m 2 or less can easily suppress damage to the diaphragm due to contact between the first layer and the diaphragm.
  • the first fiber aggregate having a basis weight of 100 g / m 2 or less easily diffuses the electrolytic solution.
  • the thickness of the first fiber aggregate is 5 ⁇ m or more and 3000 ⁇ m or less.
  • the first fiber aggregate having a thickness of 5 ⁇ m or more can easily suppress damage to the diaphragm due to contact between at least one of the positive electrode and the negative electrode and the diaphragm.
  • the first fiber aggregate having a thickness of 3000 ⁇ m or less easily diffuses the electrolytic solution.
  • the density of the first fiber aggregate is 0.1 g / cm 3 or more and 1.2 g / cm 3 or less.
  • the insulating material is a resin or ceramics
  • the resin is polyphenylene sulfide, polyethylene, polypropylene, polyamide, polyvinyl chloride, polystyrene, polybutylene succinate, acrylic, poly. It is tetrafluoroethylene, tetrafluoroethylene / ethylene copolymer, polycarbonate, phenol, or epoxy, and the ceramics may be silica, alumina, zirconia, or silicon carbide.
  • the first fiber aggregate composed of the first fiber made of resin is more susceptible to damage to the diaphragm due to contact between the first layer and the diaphragm than the first fiber aggregate composed of the first fiber made of ceramics. Easy to suppress. This is because, in general, the first fiber made of resin is softer than the first fiber made of ceramics.
  • the first fiber aggregate composed of the first fiber made of ceramics is easier to diffuse the electrolytic solution than the first fiber aggregate composed of the first fiber made of resin. This is because the first fiber made of ceramics is easier to improve the strength of the first fiber aggregate than the first fiber made of resin, so that the number of first fibers can be easily reduced. That is, the first fiber made of ceramics is more likely to increase the porosity of the first fiber aggregate than the first fiber made of resin.
  • the average Young's modulus of the plurality of first fibers is 200 GPa or less.
  • the first fiber aggregate can easily suppress the damage to the diaphragm due to the contact between the first layer and the diaphragm.
  • the thickness of the diaphragm is 60 ⁇ m or less.
  • the thickness of the diaphragm is 60 ⁇ m or less, damage to the diaphragm is easily suppressed by arranging the first layer as described above.
  • the electrode adjacent to at least the first layer of the positive electrode and the negative electrode is a second fiber aggregate having a plurality of second fibers made of a conductive material.
  • the second fiber aggregate may be a non-woven fabric, a woven cloth, or a paper.
  • the electrode adjacent to the first layer is a second fiber aggregate, damage to the diaphragm is easily suppressed by arranging the first layer as described above.
  • the cell stack according to one aspect of the present disclosure includes a plurality of battery cells, and at least one of the plurality of battery cells is any one of the above (1) to (8).
  • the cell stack of the present disclosure includes the above battery cells, it is easy to improve the current efficiency and reduce the reaction resistivity at the same time.
  • the redox flow battery system according to one aspect of the present disclosure includes any one of the battery cells (1) to (8) above, or the cell stack according to (9) above.
  • the redox flow battery system of the present disclosure includes the battery cell or the cell stack, it is easy to improve the current efficiency and reduce the reaction resistivity at the same time.
  • the redox flow battery system may be referred to as an RF battery system.
  • the RF battery system 1 of the embodiment will be described with reference to FIGS. 1 to 5.
  • the RF battery system 1 includes a battery cell 10 and a circulation mechanism.
  • the battery cell 10 has a positive electrode 14, a negative electrode 15, and a diaphragm 11.
  • the diaphragm 11 is arranged between the positive electrode 14 and the negative electrode 15.
  • the circulation mechanism circulates the electrolytic solution in the battery cell 10.
  • a specific first layer 17 is arranged between the positive electrode 14 and the diaphragm 11 and at least one between the negative electrode 15 and the diaphragm 11. There is a point to prepare.
  • the first layer 17 is arranged between the positive electrode 14 and the diaphragm 11.
  • the first layer 17 is not arranged between the negative electrode 15 and the diaphragm 11.
  • the RF battery system 1 shown in FIG. 1 charges and discharges electric power.
  • the charging power is the power generated by the power generation unit 510.
  • the discharge power is supplied to the load 530.
  • Examples of the power generation unit 510 include a solar power generation device, a wind power generation device, and other general power plants.
  • Examples of the load 530 include electric power consumers.
  • the RF battery system 1 is typically connected to the power generation unit 510 and the load 530 via the AC / DC converter 500 and the substation equipment 520.
  • the solid arrow between the AC / DC converter 500 and the substation equipment 520 in FIG. 1 means charging, and the broken line arrow means discharging.
  • the RF battery system 1 is used, for example, for load leveling applications, applications such as instantaneous low compensation or emergency power supply, and applications for smoothing the output of natural energy such as solar power generation or wind power generation, which are being introduced in large quantities.
  • the RF battery system 1 uses a positive electrode electrolytic solution and a negative electrode electrolytic solution.
  • the positive electrode electrolytic solution and the negative electrode electrolytic solution contain metal ions whose valences change due to redox as an active material.
  • the charging / discharging of the RF battery system 1 is performed by utilizing the difference between the redox potential of the metal ions contained in the positive electrode electrolytic solution and the redox potential of the metal ions contained in the negative electrode electrolytic solution.
  • the RF battery system 1 includes a battery cell 10.
  • the battery cell 10 includes a positive electrode cell and a negative electrode cell.
  • the positive electrode cell and the negative electrode cell are separated by a diaphragm 11 described later.
  • the positive electrode cell has a built-in positive electrode 14 which will be described later.
  • the positive electrode electrolytic solution circulates in the positive electrode cell by the positive electrode circulation mechanism 10P.
  • the positive electrode circulation mechanism 10P includes a positive electrode electrolyte tank 18, a supply pipe 20, a discharge pipe 22, and a pump 24.
  • the positive electrode electrolyte tank 18 stores the positive electrode electrolyte.
  • the positive electrode electrolyte flows through the supply pipe 20 and the discharge pipe 22.
  • the supply pipe 20 connects the positive electrode electrolyte tank 18 and the positive electrode cell.
  • the discharge pipe 22 connects the positive electrode cell and the positive electrode electrolyte tank 18.
  • the pump 24 pumps the positive electrode electrolyte in the positive electrode electrolyte tank 18.
  • the pump 24 is provided in the middle of the supply pipe 20.
  • the negative electrode cell has a built-in negative electrode 15 which will be described later.
  • the negative electrode electrolytic solution is circulated in the negative electrode cell by the negative electrode circulation mechanism 10N.
  • the negative electrode circulation mechanism 10N includes a negative electrode electrolyte tank 19, a supply pipe 21, a discharge pipe 23, and a pump 25.
  • the negative electrode electrolyte tank 19 stores the negative electrode electrolyte.
  • the negative electrode electrolyte flows through the supply pipe 21 and the discharge pipe 23.
  • the supply pipe 21 connects the negative electrode electrolyte tank 19 and the negative electrode cell.
  • the discharge pipe 23 connects the negative electrode cell and the negative electrode electrolyte tank 19.
  • the pump 25 pumps the negative electrode electrolyte in the negative electrode electrolyte tank 19.
  • the pump 25 is provided in the middle of the supply pipe 21.
  • the positive electrode electrolytic solution and the negative electrode electrolytic solution pumped by the pump 24 and the pump 25 circulate as follows.
  • the positive electrode electrolyte flows through the supply pipe 20 and is supplied from the positive electrode electrolyte tank 18 to the positive electrode cell.
  • This positive electrode electrolyte flows through the discharge pipe 22 and is discharged from the positive electrode cell to the positive electrode electrolyte tank 18.
  • the negative electrode electrolytic solution flows through the supply pipe 21 and is supplied from the negative electrode electrolytic solution tank 19 to the negative electrode cell.
  • This negative electrode electrolytic solution flows through the discharge pipe 23 and is discharged from the negative electrode cell to the negative electrode electrolytic solution tank 19.
  • the pump 24 and the pump 25 are stopped during standby when charging / discharging is not performed. That is, the positive electrode electrolyte and the negative electrode electrolyte do not circulate.
  • the first layer 17 suppresses contact between the electrode 100 and the diaphragm 11, which will be described later. By suppressing the contact between the electrode 100 and the diaphragm 11, damage to the diaphragm 11 due to the contact between the electrode 100 and the diaphragm 11 is suppressed. By suppressing damage to the diaphragm 11, it is possible to prevent the positive electrode electrolyte and the negative electrode electrolyte from being short-circuited through the damaged portion of the diaphragm 11. By suppressing short circuits, current efficiency is improved.
  • the first layer 17 is separate from the electrode 100. The first layer 17 is arranged between the positive electrode 14 and the diaphragm 11 and between at least one of the negative electrode 15 and the diaphragm 11.
  • the planar shape of the first layer 17 is a rectangular shape.
  • the planar shape is the contour shape of the first surface or the second surface when the first surface or the second surface of the first layer 17 is viewed in a plan view.
  • the first surface is the surface facing the electrode 100.
  • the second surface is the surface facing the diaphragm 11.
  • the rectangular shape referred to here includes a rectangle and a square. This point is the same for the planar shape of the electrode 100 and the planar shape of the diaphragm 11, which will be described later.
  • the first layer 17 is composed of the first fiber aggregate 171.
  • the first fiber assembly 171 has a plurality of first fibers 171a. Each first fiber 171a is made of an insulating material.
  • the average diameter of the plurality of first fibers 171a is 2 ⁇ m or more.
  • the first fiber 171a having an average diameter of 2 ⁇ m or more tends to improve the strength of the first fiber aggregate 171.
  • the average diameter of the first fiber 171a is preferably the same as or larger than the average diameter of the second fiber 111a constituting the electrode 100.
  • the average diameter of the plurality of first fibers 171a may be further 5 ⁇ m or more, and particularly 8 ⁇ m or more.
  • the average diameter of the plurality of first fibers 171a is 50 ⁇ m or less.
  • the first fiber 171a having an average diameter of 50 ⁇ m or less has low rigidity, and damage to the diaphragm 11 due to contact between the first layer 17 and the diaphragm 11 is likely to be suppressed.
  • the average diameter of the plurality of first fibers 171a may be further 30 ⁇ m or less, and particularly 20 ⁇ m or less.
  • the average diameter of the plurality of first fibers 171a is 2 ⁇ m or more and 50 ⁇ m or less, further 5 ⁇ m or more and 30 ⁇ m or less, and particularly 8 ⁇ m or more and 20 ⁇ m or less.
  • the average diameter of the plurality of first fibers 171a is obtained as follows.
  • the first layer 17 is cut to expose the cross section of the first fiber 171a.
  • the cutting of the first layer 17 is performed in the thickness direction of the first layer 17. Enlarge the cross section with a microscope.
  • the magnification of the microscope is 1000 times.
  • the diameter of each first fiber 171a is determined.
  • the diameter is the diameter of a circle having the same area as the cross-sectional area of the first fiber 171a. Average the diameters of all the circles found.
  • the average Young's modulus of the plurality of first fibers 171a is, for example, 200 GPa or less.
  • the first fiber aggregate 171 can easily suppress damage to the diaphragm 11 due to contact between the first layer 17 and the diaphragm 11.
  • the average Young's modulus of the plurality of first fibers 171a is preferably smaller than the Young's modulus of the second fibers 111a constituting the electrode 100.
  • the average Young's modulus of the plurality of first fibers 171a is smaller than the average Young's modulus of the plurality of second fibers 111a, damage to the diaphragm 11 due to contact between the first layer 17 and the diaphragm 11 is likely to be suppressed. Further, the average Young's modulus of the plurality of first fibers 171a is 150 GPa or less, 100 GPa or less, and particularly 10 GPa or less.
  • the lower limit of the average Young's modulus of the plurality of first fibers 171a is, for example, 100 MPa. Since the average Young's modulus of the plurality of first fibers 171a is 100 MPa or more, the strength of the first fiber aggregate 171 can be easily improved.
  • the average Young's modulus of the plurality of first fibers 171a is 100 MPa or more and 200 GPa or less, further 100 MPa or more and 150 GPa or less, 300 MPa or more and 100 GPa or less, and particularly 500 MPa or more and 10 GPa or less.
  • the average Young's modulus of the plurality of first fibers 171a is a value obtained by averaging the Young's modulus of five or more first fibers 171a.
  • Examples of the insulating material constituting the first fiber 171a include resin and ceramics.
  • Examples of the resin include polyphenylene sulfide, polyethylene, polypropylene, polyamide, polyvinyl chloride, polystyrene, polybutylene succinate, acrylic, polytetrafluoroethylene, tetrafluoroethylene / ethylene copolymer, polycarbonate, phenol, and epoxy.
  • Examples of the resin include polyphenylene sulfide.
  • Examples of the ceramics include silica, alumina, zirconia, and silicon carbide.
  • the first fiber assembly 171 made of the first fiber 171a made of resin is in contact with the first layer 17 and the diaphragm 11 more than the first fiber assembly 171 made of the first fiber 171a made of ceramics. It is easy to suppress the damage of the diaphragm 11 due to the above. This is because, in general, the first fiber 171a made of resin is softer than the first fiber 171a made of ceramics.
  • the first fiber aggregate 171 made of the first fiber 171a made of ceramics is easier to diffuse the electrolytic solution than the first fiber aggregate 171 made of the first fiber 171a made of resin.
  • the first fiber 171a made of ceramics is easier to improve the strength of the first fiber aggregate 171 than the first fiber 171a made of resin, so that the number of first fibers 171a can be easily reduced. That is, the first fiber 171a made of ceramics is easier to increase the porosity of the first fiber aggregate 171 than the first fiber 171a made of resin.
  • the insulating material constituting the first fiber 171a is preferably a material softer than the constituent material of the second fiber 111a constituting the electrode 100.
  • the first fiber 171a made of a soft material can easily suppress damage to the diaphragm 11 due to contact between the first layer 17 and the diaphragm 11.
  • the material of the first fiber 171a is obtained by X-ray diffraction.
  • the porosity P 1 of the first fiber aggregate 171 is 20% or more and 99% or less.
  • the porosity P1 of the first fiber aggregate 171 is the porosity of the first fiber aggregate 171 in the compressed state.
  • the compressed state refers to a state after assembling the battery cell 10 or the cell stack 200 described later.
  • the first fiber aggregate 171 having a porosity P 1 of 20% or more easily diffuses the electrolytic solution.
  • the first fiber aggregate 171 having a porosity P1 of 99% or less can easily prevent the second fibers 111a constituting the electrode 100 from penetrating the diaphragm 11 through the voids of the first fiber aggregate 171. Therefore, damage to the diaphragm 11 is suppressed.
  • the first fiber aggregate 171 having a porosity P1 of 99% or less easily retains the shape of the first fiber aggregate 171.
  • the porosity P 1 of the first fiber aggregate 171 is further referred to as 25% or more and 99% or less, 30% or more and 95% or less, and particularly 35% or more and 90% or less.
  • the porosity P 1 of the first fiber assembly 171 is preferably larger than the porosity of the electrode 100.
  • the first fiber aggregate 171 having a porosity P 1 larger than the porosity of the electrode 100 can easily suppress damage to the diaphragm 11 due to contact with the diaphragm 11.
  • P 0 is the porosity of the electrode 100 in the uncompressed state.
  • the porosity P0 of the electrode 100 in the uncompressed state is determined by the mercury intrusion method.
  • d 0 is the thickness of the first fiber assembly 171 in the uncompressed state.
  • d 1 is the thickness of the first fiber assembly 171 in the compressed state.
  • the thickness d 1 of the first fiber assembly 171 in the compressed state is determined by a compression test.
  • a pressure equivalent to the pressure acting on the first fiber assembly 171 is applied to the first fiber assembly 171 in a state after the battery cell 10 or the cell stack 200 described later is assembled.
  • the thickness d 0 and the thickness d 1 are the average values of the thicknesses of five or more places.
  • an example of the measurement points of the thickness d 0 and the thickness d 1 is at least the first intersection C1 to the fifth intersection C5.
  • FIG. 5 illustrates a case where the planar shape of the first fiber assembly 171 is rectangular.
  • the length of the short side of the rectangle is the width Wa
  • the length of the long side of the rectangle is the length La.
  • the first intersection C1 is the intersection of the first virtual line V1 and the third virtual line V3.
  • the second intersection C2 is the intersection of the first virtual line V1 and the fourth virtual line V4.
  • the third intersection C3 is the intersection of the second virtual line V2 and the third virtual line V3.
  • the fourth intersection C4 is the intersection of the second virtual line V2 and the fourth virtual line V4.
  • the fifth intersection C5 is the intersection of the diagonal lines D1 and D2.
  • the first virtual line V1 is a straight line along the short side direction of the first fiber assembly 171 and the distance from the first short side of the first fiber assembly 171 to the first virtual line V1 is the length La ⁇ . It is a straight line having a length of 0.1 times or more and La ⁇ 0.2 times or less.
  • the second virtual line V2 is a straight line along the short side direction of the first fiber assembly 171 and the distance from the second short side of the first fiber assembly 171 to the second virtual line V2 is the length La ⁇ . It is a straight line having a length of 0.1 times or more and La ⁇ 0.2 times or less.
  • the distance from the first short side to the first virtual line V1 and the distance from the second short side to the second virtual line V2 are the same.
  • the third virtual line V3 is a straight line along the long side direction of the first fiber assembly 171 and the distance from the first long side of the first fiber assembly 171 to the third virtual line V3 is width Wa ⁇ 0. . It is a straight line having a width of 1 times or more and a width of Wa ⁇ 0.2 times or less.
  • the fourth virtual line V4 is a straight line along the long side direction of the first fiber assembly 171 and the distance from the second long side of the first fiber assembly 171 to the fourth virtual line V4 is width Wa ⁇ 0. . It is a straight line having a width of 1 times or more and a width of Wa ⁇ 0.2 times or less.
  • the distance from the first long side to the third virtual line V3 and the distance from the second long side to the fourth virtual line V4 are the same.
  • the first virtual line V1 and the second virtual line V2 are evenly divided, and one or more additional virtual lines intersecting the third virtual line V3 and the fourth virtual line V4 are taken.
  • the third virtual line V3 and the fourth virtual line V4 are evenly divided, and one or more additional virtual lines intersecting the first virtual line V1 and the second virtual line V2 are taken.
  • one or more additional intersections are lined up between the first intersection C1 and the third intersection C3 on the third virtual line V3, and the second intersection C2 on the fourth virtual line V4.
  • One or more additional intersections are lined up with the fourth intersection C4.
  • the number of additional intersections on the third virtual line V3 and the number of additional intersections on the fourth virtual line V4 are the same.
  • the additional intersections on the third virtual line V3, the first intersection C1 and the third intersection C3 are arranged at equal intervals.
  • the additional intersections on the fourth virtual line V4, the second intersection C2, and the fourth intersection C4 are arranged at equal intervals.
  • one or more additional intersections are arranged between the first intersection C1 and the second intersection C2 on the first virtual line V1 and the third intersection C3 on the second virtual line V2.
  • One or more additional intersections are lined up with the fourth intersection C4.
  • the number of additional intersections on the first virtual line V1 and the number of additional intersections on the second virtual line V2 are the same.
  • the additional intersections on the first virtual line V1, the first intersection C1 and the second intersection C2 are arranged at equal intervals.
  • the additional intersections on the second virtual line V2, the third intersection C3, and the fourth intersection C4 are arranged at equal intervals.
  • the basis weight of the first fiber aggregate 171 is, for example, 5 g / m 2 or more and 100 g / m 2 or less.
  • the first fiber aggregate 171 having a basis weight of 5 g / m 2 or more can easily prevent the second fibers 111a constituting the electrode 100 from penetrating the diaphragm 11 through the voids of the first fiber aggregate 171.
  • the first fiber aggregate 171 having a basis weight of 5 g / m 2 or more easily suppresses the first fiber 171a from sticking to the diaphragm 11.
  • the first fiber aggregate 171 having a basis weight of 100 g / m 2 or less easily diffuses the electrolytic solution.
  • the basis weight of the first fiber aggregate 171 is further 8 g / m 2 or more and 50 g / m 2 or less, and particularly 10 g / m 2 or more and 30 g / m 2 or less.
  • the thickness of the first fiber assembly 171 is, for example, 5 ⁇ m or more and 3000 ⁇ m or less.
  • the thickness of the first fiber assembly 171 is the thickness d 1 of the first fiber assembly 171 in the compressed state described above. That is, the thickness of the first fiber assembly 171 is determined by the measurement method as described above with reference to FIG.
  • the first fiber assembly 171 having a thickness of 5 ⁇ m or more can easily prevent the second fiber 111a of the electrode 100 from penetrating the diaphragm 11 through the voids of the first fiber assembly 171. Even if the thickness of the first fiber aggregate 171 is 5 ⁇ m or more, the first fiber aggregate 171 easily diffuses the electrolytic solution by satisfying the above - mentioned porosity P1.
  • the first fiber aggregate 171 having a thickness of 3000 ⁇ m or less easily diffuses the electrolytic solution.
  • the thickness of the first fiber assembly 171 is further 8 ⁇ m or more and 200 ⁇ m or less, and particularly 10 ⁇ m or more and 100 ⁇ m or less.
  • the thickness of the first fiber assembly 171 is the average value of the thicknesses of five or more places.
  • the density of the first fiber assembly 171 is, for example, 0.1 g / cm 3 or more and 1.2 g / cm 3 or less.
  • the first fiber assembly 171 having a density of 0.1 g / cm 3 or more can easily prevent the second fiber 111a of the electrode 100 from penetrating the diaphragm 11 through the voids of the first fiber assembly 171.
  • the first fiber aggregate 171 having a density of 1.2 g / cm 3 or less easily diffuses the electrolytic solution.
  • the density of the first fiber aggregate 171 is 0.1 g / cm 3 or more and 1.0 g / cm 3 or less, 0.2 g / cm 3 or more and 0.95 g / cm 3 or less, and is particularly 0.3 g / cm. 3 or more and 0.9 g / cm 3 or less can be mentioned.
  • the density of the first fiber aggregate 171 is obtained by dividing the basis weight of the first fiber aggregate 171 by the thickness of the first fiber aggregate 171. As described above, the thickness of the first fiber aggregate 171 referred to here is the thickness d 1 of the first fiber aggregate 171 in the compressed state.
  • the positive electrode 14 and the negative electrode 15 are places where a battery reaction is performed.
  • the positive electrode 14 and the negative electrode 15 may use the same electrodes or different electrodes from each other.
  • the electrode adjacent to the first layer 17 is composed of the electrode 100.
  • the electrodes that are not adjacent to the first layer 17 may be composed of the electrode 100 or may be composed of an electrode different from the electrode 100.
  • a known electrode can be used as an electrode different from the electrode 100.
  • An example of the planar shape of the electrode 100 is a rectangular shape.
  • the planar shape is a shape when the first surface or the second surface of the electrode 100 is viewed from the thickness direction of the electrode 100.
  • the first surface is a surface facing the bipolar plate 161 described later.
  • the second surface is the surface facing the first layer 17 or the diaphragm 11.
  • the electrode 100 is made of a porous material.
  • a second fiber assembly 111 can be mentioned.
  • the second fiber assembly 111 has a plurality of second fibers 111a made of a conductive material. Since the contact between the electrode 100 and the diaphragm 11 is easily suppressed by the first layer 17, even if the electrode 100 is the second fiber aggregate 111, the decrease in current efficiency is easily suppressed.
  • the second fiber assembly 111 tends to increase the number of contacts between the second fibers 111a. Therefore, the electrode 100 composed of the second fiber assembly 111 tends to improve the conductivity. Further, the second fiber assembly 111 can easily secure a gap.
  • the electrode 100 composed of the second fiber assembly 111 tends to improve the flowability of the electrolytic solution.
  • the second fiber assembly 111 include non-woven fabric, woven fabric, and paper.
  • the non-woven fabric is made by entwining independent second fibers 111a.
  • the woven fabric is made by alternately weaving the warp and weft of the second fiber 111a.
  • the paper has a plurality of second fibers 111a and a binder for binding the second fibers 111a.
  • Nonwoven fabrics include felt, spunlace, marifleece and the like.
  • the average diameter of the plurality of second fibers 111a is, for example, 1 ⁇ m or more and 20 ⁇ m or less.
  • the second fiber 111a having an average diameter of 1 ⁇ m or more tends to increase the strength of the second fiber assembly 111. Since the second fiber 111a having an average diameter of 20 ⁇ m or less has a large surface area of the second fiber 111a per unit weight, it is easy to improve the battery reactivity. Further, the average diameter of the plurality of second fibers 111a is 5 ⁇ m or more and 18 ⁇ m or less, and particularly 8 ⁇ m or more and 15 ⁇ m or less.
  • the method of obtaining the average diameter of the plurality of second fibers 111a is the same as the method of obtaining the average diameter of the plurality of first fibers 171a.
  • the average Young's modulus of the plurality of second fibers 111a is, for example, 200 GPa or more. Even if the average Young's modulus of the plurality of second fibers 111a is 200 GPa or more, the first layer 17 tends to suppress damage to the diaphragm 11 due to contact between the electrode 100 and the diaphragm 11.
  • the average Young's modulus of the plurality of second fibers 111a further includes 250 GPa or more, and particularly 300 GPa or more.
  • the upper limit of the average Young's modulus of the plurality of second fibers 111a is, for example, 500 GPa.
  • the average Young's modulus of the plurality of second fibers 111a is 450 GPa or less, and in particular, 400 GPa or less. That is, the average Young's modulus of the plurality of second fibers 111a is 200 GPa or more and 500 GPa or less, further 250 GPa or more and 450 GPa or less, and particularly 300 GPa or more and 400 GPa or less.
  • the method of obtaining the average Young's modulus of the plurality of second fibers 111a is the same as the method of obtaining the average Young's modulus of the plurality of first fibers 171a.
  • Examples of the second fiber 111a include carbon fibers. Carbon fiber tends to improve battery reactivity. Examples of the carbon fiber include pitch-based carbon fiber and PAN (polyacrylonitrile) -based carbon fiber. Pitch-based carbon fibers are made from petroleum pitch or coal pitch. The PAN-based carbon fiber is made from polyacrylonitrile. The rigidity of these carbon fibers is relatively high. Even in the electrode 100 composed of the second fiber aggregate 111 having a plurality of these carbon fibers, the first layer 17 tends to suppress the damage of the diaphragm 11 due to the contact between the electrode 100 and the diaphragm 11.
  • the electrode 100 may have a binder that binds the second fibers 111a to each other.
  • the Young's modulus of the electrode 100 having a binder tends to be larger than that of the electrode 100 having no binder. Even in the electrode 100 having a binder, the first layer 17 tends to suppress damage to the diaphragm 11 due to contact between the electrode 100 and the diaphragm 11.
  • the material of the binder includes a material that is difficult to dissolve in the electrolytic solution.
  • the binder contains one or more selected from the group consisting of resins, metals, carbides, and metal oxides. A binder containing these materials can easily firmly fix the second fibers 111a to each other.
  • the resin include phenol, polytetrafluoroethylene, and polyvinylidene fluoride.
  • the metal include Ti (titanium) and W (tungsten).
  • the carbide include titanium carbide, manganese carbide, and tungsten carbide.
  • the metal oxide include alumina and tin oxide.
  • the porosity of the second fiber assembly 111 is, for example, 25% or more and 90% or less.
  • the porosity of the second fiber assembly 111 is the porosity of the second fiber assembly 111 in the compressed state.
  • the second fiber aggregate 111 having a porosity of 25% or more is excellent in the flowability of the electrolytic solution.
  • the second fiber assembly 111 having a porosity of 90% or less is excellent in conductivity.
  • the porosity of the second fiber assembly 111 is further 60% or more and 80% or less, and particularly 70% or more and 80% or less.
  • the method of obtaining the porosity of the second fiber assembly 111 is the same as the method of obtaining the porosity P1 of the first fiber assembly 171.
  • the basis weight of the second fiber assembly 111 is 20 g / m 2 or more and 600 g / m 2 or less. Since the second fiber aggregate 111 having a basis weight of 20 g / m 2 or more tends to have many contacts between the second fibers 111a, it is easy to increase the conductivity. The second fiber aggregate 111 having a basis weight of 600 g / m 2 or less is excellent in the flowability of the electrolytic solution because it is easy to secure voids. The basis weight of the second fiber assembly 111 is further 50 g / m 2 or more and 550 g / m 2 or less, and particularly 100 g / m 2 or more and 500 g / m 2 or less.
  • the thickness of the second fiber assembly 111 is, for example, 200 ⁇ m or more and 1000 ⁇ m or less.
  • the thickness of the second fiber assembly 111 is the thickness of the second fiber assembly 111 in the compressed state.
  • the second fiber aggregate 111 having a thickness of 200 ⁇ m or more tends to increase the volume of the reaction field where the battery reaction is carried out.
  • the second fiber assembly 111 having a thickness of 1000 ⁇ m or less can construct a thin RF battery system 1.
  • the thickness of the second fiber assembly 111 is 300 ⁇ m or more and 800 ⁇ m or less, and particularly 400 ⁇ m or more and 700 ⁇ m or less.
  • the thickness of the second fiber assembly 111 corresponds to the depth of the recess 160 of the cell frame 16 described later.
  • the thickness of the second fiber assembly 111 is the average value of the depths of the recesses 160 at five or more locations.
  • An example of the measurement point of the thickness of the second fiber assembly 111 can be the same as the first intersection C1 to the fifth intersection C5 described with reference to FIG.
  • the density of the second fiber assembly 111 is, for example, 0.1 g / cm 3 or more and 1.2 g / cm 3 or less. Since the second fiber assembly 111 having a density of 0.1 g / cm 3 or more tends to have many contacts between the second fibers 111a, it is easy to increase the conductivity. The second fiber assembly 111 having a density of 1.2 g / cm 3 or less is excellent in the flowability of the electrolytic solution.
  • the density of the second fiber aggregate 111 further includes 0.1 g / cm 3 or more and 1.0 g / cm 3 or less, 0.2 g / cm 3 or more and 0.95 g / cm 3 or less, and particularly 0.3 g / cm. 3 or more and 0.9 g / cm 3 or less can be mentioned. The density of the second fiber assembly 111 is obtained by dividing the basis weight by the thickness.
  • the diaphragm 11 is arranged between the positive electrode 14 and the negative electrode 15.
  • the diaphragm 11 partitions the positive electrode cell and the negative electrode cell.
  • the diaphragm 11 allows hydrogen ions to permeate.
  • Examples of the type of diaphragm 11 include an ion exchange membrane.
  • An example of the planar shape of the diaphragm 11 is a rectangular shape.
  • the planar shape is the contour shape of the first surface or the second surface when the first surface or the second surface of the diaphragm 11 is viewed in a plan view.
  • the first surface is a surface facing the positive electrode electrode 14.
  • the second surface is a surface facing the negative electrode electrode 15.
  • the thickness of the diaphragm 11 is, for example, 60 ⁇ m or less.
  • the diaphragm 11 having a thickness of 60 ⁇ m or less can easily reduce the cell resistivity. This is because such a diaphragm 11 easily allows hydrogen ions to permeate, so that it is easy to reduce the electrical resistance. Even if the diaphragm 11 has a thickness of 60 ⁇ m or less, the first layer 17 suppresses damage to the diaphragm 11 due to contact between the electrode 100 and the diaphragm 11.
  • the thickness of the diaphragm 11 is further 40 ⁇ m or less, and particularly 30 ⁇ m or less.
  • the lower limit of the thickness of the diaphragm 11 is, for example, 5 ⁇ m.
  • the diaphragm 11 having a thickness of 5 ⁇ m or more is not easily damaged.
  • the thickness of the diaphragm 11 is further 8 ⁇ m or more, and particularly 10 ⁇ m or more.
  • the thickness of the diaphragm 11 is 5 ⁇ m or more and 60 ⁇ m or less, further 8 ⁇ m or more and 40 ⁇ m or less, and particularly 10 ⁇ m or more and 30 ⁇ m or less.
  • the thickness of the diaphragm 11 is the average value of the thicknesses of 5 or more places.
  • An example of the measurement point of the thickness of the diaphragm 11 can be the same as the first intersection C1 to the fifth intersection C5 described with reference to FIG.
  • the battery cell 10 is provided between the two cell frames 16.
  • the cell frame 16 includes a bipolar plate 161 and a frame body 162.
  • the cell frame 16 includes a recess 160 in which the positive electrode 14 or the negative electrode 15 is arranged.
  • the recess 160 is formed by the surface of the bipolar plate 161 and the inner peripheral surface of the frame body 162.
  • One battery cell 10 is formed between the bipolar plates 161 of the adjacent cell frames 16.
  • a positive electrode cell and a negative electrode cell of adjacent battery cells 10 are formed on the front and back sides of one bipolar plate 161.
  • the bipolar plate 161 and the frame body 162 may have known configurations.
  • the frame body 162 surrounds the outer peripheral edge portion of the bipolar plate 161. The region inside the outer peripheral edge of the surface of the bipolar plate 161 is exposed from the frame body 162.
  • the frame body 162 supports the bipolar plate 161.
  • the frame body 162 forms an area to be the battery cell 10 inside.
  • the shape of the frame body 162 is a rectangular frame shape. That is, the opening shape of the recess 160 is rectangular.
  • the frame body 162 includes a liquid supply side piece and a liquid drainage side piece. When the cell frame 16 is viewed in a plan view, the direction in which the liquid supply side piece and the liquid drainage side piece face each other is the vertical direction, and the direction orthogonal to the vertical direction is the horizontal direction. In FIG.
  • the liquid supply side piece is located on the lower side in the vertical direction, and the liquid drain side piece is located on the upper side in the vertical direction.
  • the liquid supply side piece has a liquid supply manifolds 163 and 164 and liquid supply slits 163s and 164s that supply the electrolytic solution to the inside of the battery cell 10.
  • the drainage side piece has a drainage manifold 165, 166 and drainage slits 165s, 166s for draining the electrolytic solution to the outside of the battery cell 10.
  • the direction in which the electrolytic solution flows is from the lower side in the vertical direction to the upper side in the vertical direction of the frame body 162.
  • a liquid supply rectifying unit may be formed on the inner edge of the liquid supply side piece.
  • the liquid supply rectifying unit diffuses the electrolytic solution supplied from the liquid supply slits 163s and 164s along the inner edge of the liquid supply side piece.
  • a drainage rectifying portion may be formed on the inner edge of the drainage side piece.
  • the effluent rectifying unit collects the electrolytic solution flowing through the positive electrode 14 or the negative electrode 15 from the entire inner edge of the effluent side piece and circulates it through the effluent slits 165s and 166s.
  • the illustration of the liquid supply rectifying unit and the drainage rectifying unit is omitted.
  • each electrode electrolyte in the cell frame 16 is as follows.
  • the positive electrode electrolytic solution flows from the liquid supply manifold 163 through the liquid supply slit 163s formed in the liquid supply side piece on the first surface side of the frame body 162 and is supplied to the positive electrode electrode 14.
  • the positive electrode electrolytic solution flows from the lower side to the upper side of the positive electrode electrode 14 and flows through the drainage slit 165s formed in the drainage side piece to drain the drainage manifold 165. Is discharged to.
  • the supply and discharge of the negative electrode electrolytic solution are the same as those of the positive electrode electrolytic solution except that the negative electrode electrolytic solution is supplied and discharged on the second surface side of the frame body 162.
  • the first surface and the second surface of the frame body 162 are surfaces facing each other in the thickness direction of the frame body 162.
  • annular seal member 167 such as an O-ring or flat packing is arranged in an annular seal groove.
  • the seal member 167 suppresses leakage of the electrolytic solution from the battery cell 10.
  • the battery cell 10 is usually provided inside a structure called a cell stack 200, as shown in FIGS. 1 and 2 below.
  • the cell stack 200 includes a sub-stack 200s, two end plates 220, and a tightening mechanism 230.
  • the cell stack 200 includes a plurality of sub-stacks 200s, for example, as shown in the lower figure of FIG.
  • Each sub-stack 200s includes a laminated body and two supply / discharge plates 210.
  • the laminate shown in FIGS. 1 and 2 is composed of a plurality of cell frames 16, positive electrode 14, first layer 17, diaphragm 11, and negative electrode 15 in this order.
  • the supply / discharge plate 210 is arranged at both ends of the laminated body.
  • the two end plates 220 sandwich the plurality of sub-stacks 200s from the outside of the sub-stacks 200s at both ends.
  • the tightening mechanism 230 tightens both end plates 220.
  • the cell frame 16 provided in the sub-stack 200s and the cell stack 200 includes an intermediate cell frame and an end cell frame.
  • the intermediate cell frame is arranged between the adjacent battery cells 10 of the laminated body.
  • the end cell frames are arranged at both ends of the laminate.
  • the positive electrode 14 of the first battery cell 10 is in contact with the first surface of the bipolar plate 161.
  • the negative electrode 15 of the second battery cell 10 is in contact with the second surface of the bipolar plate 161.
  • one of the positive electrode 14 and the negative electrode 15 of the battery cell 10 is in contact with the first surface of the bipolar plate 161.
  • the end cell frame has no electrodes on the second surface of the bipolar plate 161.
  • the first surface and the second surface of the bipolar plate 161 are surfaces facing each other in the thickness direction of the bipolar plate 161.
  • the configuration of the cell frame 16 is the same for both the intermediate cell frame and the end cell frame.
  • the positive electrode electrolytic solution and the negative electrode electrolytic solution are circulated to the positive electrode electrode 14 and the negative electrode electrode 15 by the positive electrode circulation mechanism 10P and the negative electrode circulation mechanism 10N.
  • charging and discharging are performed according to the valence change reaction of ions which are active materials contained in the positive electrode electrolytic solution and the negative electrode electrolytic solution.
  • the active material of the positive electrode electrolytic solution may contain one or more selected from the group consisting of manganese ion, vanadium ion, iron ion, polyacid, quinone derivative, and amine.
  • the active material of the negative electrode electrolytic solution may contain one or more selected from the group consisting of titanium ion, vanadium ion, chromium ion, polyacid, quinone derivative, and amine.
  • FIG. 1 illustrates a form in which the positive electrode electrolytic solution contains manganese (Mn) ions and the negative electrode electrolytic solution contains titanium (Ti) ions.
  • the concentration of the positive electrode active material and the concentration of the negative electrode active material can be appropriately selected.
  • at least one of the concentration of the positive electrode active material and the concentration of the negative electrode active material is 0.3 mol / L or more and 5 mol / L or less.
  • the energy density is, for example, about 10 kWh / m 3 .
  • the higher the concentration the higher the energy density.
  • the above-mentioned concentration is 0.5 mol / L or more and 1.0 mol / L or more, and particularly 1.2 mol / L or more and 1.5 mol / L or more.
  • the solubility in a solvent can be easily increased. It is easy to use the above concentration of 2 mol / L or less.
  • An electrolytic solution satisfying this concentration is excellent in manufacturability.
  • Examples of the solvent of the electrolytic solution include an aqueous solution containing one or more acids or acid salts selected from the group consisting of sulfuric acid, phosphoric acid, nitric acid, and hydrochloric acid.
  • the RF battery system 1 of this embodiment can easily achieve both improvement in current efficiency and reduction in reaction resistivity.
  • the first layer 17 suppresses damage to the diaphragm 11 due to contact between at least one of the positive electrode 14 and the negative electrode 15 and the diaphragm 11.
  • damage to the diaphragm 11 due to contact between the plurality of first fibers 171a constituting the first layer 17 and the diaphragm 11 is suppressed.
  • the first layer 17 easily diffuses the electrolytic solution. Therefore, the RF battery system 1 of the present disclosure tends to reduce the reaction resistivity.
  • Test example the difference in battery characteristics due to the presence or absence of the first layer and the difference in the configuration of the first layer was investigated.
  • Sample No. 1 Sample No. In No. 1, a single cell battery was prepared as the battery cell. The single cell battery was constructed by stacking the first cell frame, the positive electrode, the diaphragm, the negative electrode, and the second cell frame in this order. Sample No. In battery cell 1, the first layer is not arranged between the positive electrode and the diaphragm and between the negative electrode and the diaphragm. “-” In the column of the first layer shown in Table 2 means that the first layer is not arranged.
  • a cation exchange membrane was used as the diaphragm.
  • the thickness of the diaphragm was 15 ⁇ m.
  • the thickness of the diaphragm was determined by averaging the thicknesses of the above-mentioned five or more locations.
  • a non-woven fabric made of carbon fiber was used for the positive electrode.
  • the specifications of the positive electrode are as shown in Table 1.
  • the method for measuring the average diameter and the average Young's modulus of the carbon fibers constituting the positive electrode and the method for measuring the thickness, the amount of the grain, the density, and the void ratio of the positive electrode are described in Sample No. It will be described later together with the measurement method of the first layer such as 2.
  • the same non-woven fabric as the positive electrode was used for the negative electrode.
  • the reaction area of each of the positive electrode and the negative electrode was about 9 cm 2 .
  • sample No. From sample No. 2 7 Sample No. From sample No. 2 In No. 7, the sample No. 7 was prepared except that the first layer was arranged between the positive electrode and the diaphragm. A single cell battery similar to the battery cell of No. 1 was prepared. Sample No. From sample No. 2 In the RF battery system of No. 7, the first layer is not arranged between the negative electrode and the diaphragm. Sample No. From sample No. 2 The first layer of 6 is a first fiber assembly having a plurality of first fibers composed of PPS (polyphenylene sulfide). Sample No. The first layer of No. 7 is a first fiber aggregate having a plurality of first fibers made of PE (polyethylene). Sample No. From sample No. 2 The specifications of the first layer of 7 are as shown in Table 2.
  • the average diameter and the average Young's modulus of one fiber and the thickness, the amount of the grain, the density, and the void ratio of the first layer were determined as follows.
  • the thickness is the thickness of the compressed positive electrode and the first layer.
  • the porosity is the porosity of the compressed positive electrode and the first layer.
  • the average diameter of the fibers was determined by averaging the diameters of the five fibers.
  • the diameter of each fiber is the diameter of a circle having the same area as the cross-sectional area of each fiber.
  • the average Young's modulus of the fibers was determined by averaging the Young's modulus of the five fibers.
  • the thickness was determined by averaging the thicknesses of the above-mentioned five locations.
  • the thickness of each portion is a thickness measured in a state where a pressure of 0.2 MPa is applied to the positive electrode and the first layer.
  • the basis weight was determined by measuring the weight per unit area.
  • the density was determined by dividing the basis weight by the thickness.
  • the porosity of the first layer was determined in the same manner as the method for determining the porosity P1 of the first fiber aggregate 171 described above.
  • the porosity of the positive electrode was determined by the same method as the method for determining the porosity of the first layer.
  • the current efficiency (%), cell resistivity ( ⁇ ⁇ cm 2 ), conductivity resistivity ( ⁇ ⁇ cm 2 ), and reaction resistivity ( ⁇ ⁇ cm 2 ) of each sample were determined.
  • the current efficiency was calculated by multiplying each cycle (total discharge time / total charge time) ⁇ 100 and used as an average value.
  • the cell resistivity was calculated by ⁇ (difference between average voltage during charging and average voltage during discharging) / (average current / 2) ⁇ ⁇ effective area of the electrode.
  • the average voltage during charging and the average voltage during discharging were defined as the average voltage in any one cycle among the plurality of cycles.
  • the conductivity resistivity is the impedance when the measurement frequency is 1 kHz in the AC impedance method.
  • the reaction resistivity was a value obtained by subtracting the conductivity resistivity from the cell resistivity. The results are shown in Table 3.
  • sample No. From sample No. 2 The current efficiency of No. 6 is the sample No. Higher than 1. The reason for this result is considered to be that the first layer was able to suppress the damage to the diaphragm.
  • Sample No. From sample No. 2 The reaction resistivity of No. 6 is the sample No. Less than 1. It is considered that the reason for such a result is that the diffusion of the electrolytic solution was hardly inhibited even though the first layer was provided. As a result, it is considered that the electrodes were able to carry out the battery reaction satisfactorily.
  • Sample No. The current efficiency of No. 7 is the sample No. From sample No. 2 Lower than 6. The reason for this result is the sample No. Although the porosity of the first layer of No. 7 satisfies 20% or more and 99% or less, it is considered that the first fiber damaged the diaphragm due to the increased rigidity of the first fiber having an average diameter of more than 50 ⁇ m. Be done.
  • the porosity satisfies 20% or more and 99% or less
  • the first layer having an average diameter of less than 2 ⁇ m of the first fiber is clogged, so that the flowability of the electrolytic solution deteriorates.
  • the average diameter of the first fiber satisfies 2 ⁇ m or more and 50 ⁇ m or less
  • the first layer having a porosity of less than 20% is clogged and the flowability of the electrolytic solution deteriorates.
  • the average diameter of the first fiber satisfies 2 ⁇ m or more and 50 ⁇ m or less
  • the first layer having a porosity of more than 99% cannot retain the shape of the first layer in the battery cell.

Abstract

This battery cell comprises a positive electrode, a negative electrode, and a barrier membrane, and includes a first layer that is disposed between the positive electrode and the barrier membrane and/or between the negative electrode and the barrier membrane. The first layer is a first fiber aggregate that includes a plurality of first fibers formed of an insulative material. The average diameter of the plurality of first fibers is 2 μm to 50 μm, and the void ratio of the first fiber aggregate is 20% to 99%.

Description

電池セル、セルスタック、及びレドックスフロー電池システムBattery cell, cell stack, and redox flow battery system
　本開示は、電池セル、セルスタック、及びレドックスフロー電池システムに関する。
　本出願は、２０２１年０１月１２日付の日本国出願の特願２０２１－００２８５３に基づく優先権を主張し、前記日本国出願に記載された全ての記載内容を援用するものである。 The present disclosure relates to battery cells, cell stacks, and redox flow battery systems.
This application claims priority based on Japanese Patent Application No. 2021-002853 of the Japanese application dated January 12, 2021, and incorporates all the contents described in the Japanese application.
　特許文献１のレドックスフロー電池の電池要素は、正極電極と、負極電極と、イオン交換膜と、多孔質シート材とを備える。イオン交換膜は、正極電極と負極電極の間に配置されている。多孔質シート材は、イオン交換膜における正極電極に向かい合う面と負極電極に向かい合う面の各々の面に設けられている。正極電極及び負極電極は、炭素繊維の不織布で構成されている。多孔質シート材は、有機材料で構成されている。 The battery element of the redox flow battery of Patent Document 1 includes a positive electrode, a negative electrode, an ion exchange membrane, and a porous sheet material. The ion exchange membrane is arranged between the positive electrode and the negative electrode. The porous sheet material is provided on each surface of the ion exchange membrane facing the positive electrode and the surface facing the negative electrode. The positive electrode and the negative electrode are made of a non-woven fabric made of carbon fiber. The porous sheet material is composed of an organic material.
特開２０１３－６５５３０号公報Japanese Unexamined Patent Publication No. 2013-65530
　本開示の電池セルは、正極電極と負極電極と隔膜とを備える電池セルであって、前記正極電極と前記隔膜との間及び前記負極電極と前記隔膜との間の少なくとも一方の間に配置されている第一の層を備え、前記第一の層は、絶縁材料からなる複数の第一繊維を有する第一繊維集合体であり、前記複数の第一繊維の平均直径は、２μｍ以上５０μｍ以下であり、前記第一繊維集合体の空隙率は、２０％以上９９％以下である。 The battery cell of the present disclosure is a battery cell including a positive electrode, a negative electrode, and a diaphragm, and is arranged between the positive electrode and the diaphragm and at least one of the negative electrode and the diaphragm. The first layer is a first fiber aggregate having a plurality of first fibers made of an insulating material, and the average diameter of the plurality of first fibers is 2 μm or more and 50 μm or less. The void ratio of the first fiber aggregate is 20% or more and 99% or less.
　本開示のセルスタックは、複数の電池セルを備え、前記複数の電池セルの少なくとも一つが本開示の電池セルである。 The cell stack of the present disclosure includes a plurality of battery cells, and at least one of the plurality of battery cells is the battery cell of the present disclosure.
　本開示のレドックスフロー電池システムは、本開示の電池セル、又は本開示のセルスタックを備える。 The redox flow battery system of the present disclosure includes the battery cells of the present disclosure or the cell stack of the present disclosure.
図１は、実施形態に係るレドックスフロー電池システムの概略構成図である。FIG. 1 is a schematic configuration diagram of a redox flow battery system according to an embodiment. 図２は、実施形態に係るレドックスフロー電池システムに備わるセルスタックの概略構成図である。FIG. 2 is a schematic configuration diagram of a cell stack provided in the redox flow battery system according to the embodiment. 図３は、実施形態に係るレドックスフロー電池システムに備わる第一の層の表面を拡大して示す拡大図である。FIG. 3 is an enlarged view showing an enlarged surface of the first layer provided in the redox flow battery system according to the embodiment. 図４は、実施形態に係るレドックスフロー電池システムに備わる電極の表面を拡大して示す拡大図である。FIG. 4 is an enlarged view showing an enlarged surface of an electrode provided in the redox flow battery system according to the embodiment. 図５は、実施形態に係るレドックスフロー電池システムに備わる第一の層の厚さを測定する測定箇所を示す説明図である。FIG. 5 is an explanatory diagram showing measurement points for measuring the thickness of the first layer provided in the redox flow battery system according to the embodiment.
　［本開示が解決しようとする課題］
　上記多孔質シート材は、電極とイオン交換膜との間に設けられていることによって、イオン交換膜を保護する。イオン交換膜の保護によって、電極とイオン交換膜との接触に伴うイオン交換膜の損傷が防止される。具体的には、電極の繊維がイオン交換膜に突き刺さったり、イオン交換膜に亀裂が生じたりすることが防止される。イオン交換膜の損傷の防止によって、正極電解液と負極電解液とがイオン交換膜の損傷箇所を介して短絡することが抑制される。そのため、電流効率の低下が抑制される。上記多孔質シート材は、電解液の拡散を阻害するおそれがある。電解液の拡散が阻害されれば、電池セルの反応抵抗率の上昇を招くおそれがある。 [Issues to be solved by this disclosure]
The porous sheet material protects the ion exchange membrane by being provided between the electrode and the ion exchange membrane. The protection of the ion exchange membrane prevents damage to the ion exchange membrane due to contact between the electrode and the ion exchange membrane. Specifically, it prevents the fibers of the electrode from sticking into the ion exchange membrane and cracking the ion exchange membrane. By preventing damage to the ion exchange membrane, it is possible to prevent the positive electrode electrolyte and the negative electrode electrolyte from being short-circuited through the damaged portion of the ion exchange membrane. Therefore, the decrease in current efficiency is suppressed. The porous sheet material may inhibit the diffusion of the electrolytic solution. If the diffusion of the electrolytic solution is inhibited, the reaction resistivity of the battery cell may increase.
　本開示は、電流効率の向上及び反応抵抗率の低下を両立し易い電池セル、セルスタック、及びレドックスフロー電池システムを提供することを目的の一つとする。 One of the purposes of the present disclosure is to provide a battery cell, a cell stack, and a redox flow battery system that can easily achieve both improvement in current efficiency and reduction in reaction resistivity.
　［本開示の効果］
　本開示の電池セル、セルスタック、及びレドックスフロー電池システムは、電流効率の向上及び反応抵抗率の低下を両立し易い。 [Effect of the present disclosure]
The battery cell, cell stack, and redox flow battery system of the present disclosure can easily achieve both improvement in current efficiency and reduction in reaction resistivity.
　《本開示の実施形態の説明》
　最初に本開示の実施態様を列記して説明する。 << Explanation of Embodiments of the present disclosure >>
First, embodiments of the present disclosure will be listed and described.
　（１）本開示の一態様に係る電池セルは、正極電極と負極電極と隔膜とを備える電池セルであって、前記正極電極と前記隔膜との間及び前記負極電極と前記隔膜との間の少なくとも一方の間に配置されている第一の層を備え、前記第一の層は、絶縁材料からなる複数の第一繊維を有する第一繊維集合体であり、前記複数の第一繊維の平均直径は、２μｍ以上５０μｍ以下であり、前記第一繊維集合体の空隙率は、２０％以上９９％以下である。 (1) The battery cell according to one aspect of the present disclosure is a battery cell including a positive electrode, a negative electrode, and a diaphragm, and is between the positive electrode and the diaphragm and between the negative electrode and the diaphragm. It comprises a first layer arranged between at least one of the first layers, which is a first fiber assembly having a plurality of first fibers made of an insulating material, and is an average of the plurality of first fibers. The diameter is 2 μm or more and 50 μm or less, and the void ratio of the first fiber aggregate is 20% or more and 99% or less.
　第一の層が配置されていない電池セルでは、特に電池セルの組み立て時に隔膜が損傷し易い。電池セルの組み立ては、通常、セルフレーム、正極電極、隔膜、負極電極を順に平積みして行う。その平積みの際、部材同士の位置を合わせるときに電極と隔膜とが互いに擦れることがある。電極と隔膜とが互いに過度に擦れることで、隔膜が損傷し易くなる。 In a battery cell in which the first layer is not arranged, the diaphragm is easily damaged especially when the battery cell is assembled. The battery cell is usually assembled by stacking the cell frame, the positive electrode, the diaphragm, and the negative electrode in this order. During the flat stacking, the electrodes and the diaphragm may rub against each other when aligning the members. Excessive rubbing between the electrodes and the diaphragm makes the diaphragm more susceptible to damage.
　本開示の電池セルは、正極電極及び負極電極の少なくとも一方の電極と隔膜との間に配置されている第一の層によって、電極と隔膜との接触を抑制し易い。空隙率が９９％以下の第一繊維集合体で構成されている第一の層は、電極と隔膜との間隔を保つことに寄与する。特に、空隙率が９９％以下の第一繊維集合体で構成されている第一の層は、電極が複数の第二繊維を有する第二繊維集合体で構成されていても、第二繊維が第一の層の空隙を通って隔膜に突き刺さることを抑制し易い。そのため、本開示の電池セルは、電極と隔膜との接触に伴う隔膜の損傷を抑制し易い。 In the battery cell of the present disclosure, the contact between the electrode and the diaphragm is easily suppressed by the first layer arranged between at least one of the positive electrode and the negative electrode and the diaphragm. The first layer, which is composed of the first fiber aggregate having a porosity of 99% or less, contributes to maintaining the distance between the electrode and the diaphragm. In particular, the first layer composed of the first fiber aggregate having a porosity of 99% or less has the second fiber even if the electrode is composed of the second fiber aggregate having a plurality of second fibers. It is easy to suppress the penetration of the diaphragm through the voids of the first layer. Therefore, the battery cell of the present disclosure can easily suppress damage to the diaphragm due to contact between the electrode and the diaphragm.
　第一の層は、複数の第一繊維を有する第一繊維集合体で構成されている。平均直径が２μｍ以上の第一繊維は、隔膜に突き刺さり難い。平均直径が５０μｍ以下の第一繊維は、隔膜に引っ掛かり難い。そのため、本開示の電池セルは、第一の層と隔膜との接触に伴う隔膜の損傷を抑制し易い。 The first layer is composed of a first fiber aggregate having a plurality of first fibers. The first fiber having an average diameter of 2 μm or more is unlikely to pierce the septum. The first fiber having an average diameter of 50 μm or less is less likely to be caught in the diaphragm. Therefore, the battery cell of the present disclosure can easily suppress damage to the diaphragm due to contact between the first layer and the diaphragm.
　隔膜の損傷が抑制されることで、正極電解液と負極電解液とが隔膜の損傷部分を介して短絡することが抑制される。よって、本開示の電池セルは、電流効率を向上し易い。 By suppressing the damage to the diaphragm, it is possible to prevent the positive electrode electrolyte and the negative electrode electrolyte from being short-circuited through the damaged portion of the diaphragm. Therefore, the battery cell of the present disclosure tends to improve the current efficiency.
　第一繊維集合体の空隙率が２０％以上を満たす第一の層は、電解液を拡散し易い。よって、本開示の電池セルは、反応抵抗率を低下させ易い。 The first layer in which the porosity of the first fiber aggregate satisfies 20% or more easily diffuses the electrolytic solution. Therefore, the battery cell of the present disclosure tends to reduce the reaction resistivity.
　（２）上記電池セルの一形態として、前記第一繊維集合体の目付量は、５ｇ／ｍ２以上１００ｇ／ｍ２以下であることが挙げられる。 (2) As one form of the battery cell, the basis weight of the first fiber aggregate is 5 g / m 2 or more and 100 g / m 2 or less.
　目付量が５ｇ／ｍ２以上の第一繊維集合体は、正極電極及び負極電極の少なくとも一方の電極と隔膜との接触に伴う隔膜の損傷を抑制し易い。目付量が１００ｇ／ｍ２以下の第一繊維集合体は、第一の層と隔膜との接触に伴う隔膜の損傷を抑制し易い。その上、目付量が１００ｇ／ｍ２以下の第一繊維集合体は、電解液を拡散させ易い。 The first fiber aggregate having a grain size of 5 g / m 2 or more can easily suppress damage to the diaphragm due to contact between at least one of the positive electrode and the negative electrode and the diaphragm. The first fiber aggregate having a basis weight of 100 g / m 2 or less can easily suppress damage to the diaphragm due to contact between the first layer and the diaphragm. Moreover, the first fiber aggregate having a basis weight of 100 g / m 2 or less easily diffuses the electrolytic solution.
　（３）上記電池セルの一形態として、前記第一繊維集合体の厚さは、５μｍ以上３０００μｍ以下であることが挙げられる。 (3) As one form of the battery cell, the thickness of the first fiber aggregate is 5 μm or more and 3000 μm or less.
　厚さが５μｍ以上の第一繊維集合体は、正極電極及び負極電極の少なくとも一方の電極と隔膜との接触に伴う隔膜の損傷を抑制し易い。厚さが３０００μｍ以下の第一繊維集合体は、電解液を拡散させ易い。 The first fiber aggregate having a thickness of 5 μm or more can easily suppress damage to the diaphragm due to contact between at least one of the positive electrode and the negative electrode and the diaphragm. The first fiber aggregate having a thickness of 3000 μm or less easily diffuses the electrolytic solution.
　（４）上記電池セルの一形態として、前記第一繊維集合体の密度は、０．１ｇ／ｃｍ３以上１．２ｇ／ｃｍ３以下であることが挙げられる。 (4) As one form of the battery cell, the density of the first fiber aggregate is 0.1 g / cm 3 or more and 1.2 g / cm 3 or less.
　密度が０．１ｇ／ｃｍ３以上の第一繊維集合体は、正極電極及び負極電極の少なくとも一方の電極と隔膜との接触を抑制し易い。密度が１．２ｇ／ｃｍ３以下の第一繊維集合体は、電解液を拡散させ易い。 The first fiber aggregate having a density of 0.1 g / cm 3 or more easily suppresses contact between at least one of the positive electrode and the negative electrode and the diaphragm. The first fiber aggregate having a density of 1.2 g / cm 3 or less easily diffuses the electrolytic solution.
　（５）上記電池セルの一形態として、前記絶縁材料は、樹脂、又はセラミックスであり、前記樹脂は、ポリフェニレンスルフィド、ポリエチレン、ポリプロピレン、ポリアミド、ポリ塩化ビニル、ポリスチレン、ポリブチレンサクシネート、アクリル、ポリテトラフルオロエチレン、テトラフルオロエチレン・エチレン共重合体、ポリカーボネート、フェノール、又はエポキシであり、前記セラミックスは、シリカ、アルミナ、ジルコニア、又は炭化ケイ素であることが挙げられる。 (5) As one form of the battery cell, the insulating material is a resin or ceramics, and the resin is polyphenylene sulfide, polyethylene, polypropylene, polyamide, polyvinyl chloride, polystyrene, polybutylene succinate, acrylic, poly. It is tetrafluoroethylene, tetrafluoroethylene / ethylene copolymer, polycarbonate, phenol, or epoxy, and the ceramics may be silica, alumina, zirconia, or silicon carbide.
　樹脂からなる第一繊維によって構成された第一繊維集合体は、セラミックスからなる第一繊維によって構成された第一繊維集合体よりも、第一の層と隔膜との接触に伴う隔膜の損傷を抑制し易い。一般的に、樹脂からなる第一繊維は、セラミックスからなる第一繊維よりも、柔らかいからである。セラミックスからなる第一繊維によって構成された第一繊維集合体は、樹脂からなる第一繊維によって構成された第一繊維集合体よりも、電解液を拡散させ易い。セラミックスからなる第一繊維は、樹脂からなる第一繊維よりも、第一繊維集合体の強度を向上させ易いため、第一繊維の本数を減らし易いからである。即ち、セラミックスからなる第一繊維は、樹脂からなる第一繊維よりも、第一繊維集合体の空隙率を高め易いからである。 The first fiber aggregate composed of the first fiber made of resin is more susceptible to damage to the diaphragm due to contact between the first layer and the diaphragm than the first fiber aggregate composed of the first fiber made of ceramics. Easy to suppress. This is because, in general, the first fiber made of resin is softer than the first fiber made of ceramics. The first fiber aggregate composed of the first fiber made of ceramics is easier to diffuse the electrolytic solution than the first fiber aggregate composed of the first fiber made of resin. This is because the first fiber made of ceramics is easier to improve the strength of the first fiber aggregate than the first fiber made of resin, so that the number of first fibers can be easily reduced. That is, the first fiber made of ceramics is more likely to increase the porosity of the first fiber aggregate than the first fiber made of resin.
　（６）上記電池セルの一形態として、前記複数の第一繊維の平均ヤング率は、２００ＧＰａ以下であることが挙げられる。 (6) As one form of the battery cell, the average Young's modulus of the plurality of first fibers is 200 GPa or less.
　複数の第一繊維の平均ヤング率が２００ＧＰａ以下であることで、第一繊維集合体は、第一の層と隔膜との接触に伴う隔膜の損傷を抑制し易い。 When the average Young's modulus of the plurality of first fibers is 200 GPa or less, the first fiber aggregate can easily suppress the damage to the diaphragm due to the contact between the first layer and the diaphragm.
　（７）上記電池セルの一形態として、前記隔膜の厚さは、６０μｍ以下であることが挙げられる。 (7) As one form of the battery cell, the thickness of the diaphragm is 60 μm or less.
　厚さが６０μｍ以下の隔膜であっても、上述のように第一の層が配置されていることで、隔膜の損傷が抑制され易い。 Even if the thickness of the diaphragm is 60 μm or less, damage to the diaphragm is easily suppressed by arranging the first layer as described above.
　（８）上記電池セルの一形態として、前記正極電極及び前記負極電極のうち少なくとも前記第一の層に隣り合う電極は、導電材料からなる複数の第二繊維を有する第二繊維集合体であり、前記第二繊維集合体は、不織布、織布、又はペーパーであることが挙げられる。 (8) As one form of the battery cell, the electrode adjacent to at least the first layer of the positive electrode and the negative electrode is a second fiber aggregate having a plurality of second fibers made of a conductive material. , The second fiber aggregate may be a non-woven fabric, a woven cloth, or a paper.
　第一の層に隣り合う電極が第二繊維集合体であっても、上述のように第一の層が配置されていることで、隔膜の損傷が抑制され易い。 Even if the electrode adjacent to the first layer is a second fiber aggregate, damage to the diaphragm is easily suppressed by arranging the first layer as described above.
　（９）本開示の一態様に係るセルスタックは、複数の電池セルを備え、前記複数の電池セルの少なくとも一つが上記（１）から上記（８）のいずれか１つの電池セルである。 (9) The cell stack according to one aspect of the present disclosure includes a plurality of battery cells, and at least one of the plurality of battery cells is any one of the above (1) to (8).
　本開示のセルスタックは、上記電池セルを備えるため、電流効率の向上及び反応抵抗率の低下を両立し易い。 Since the cell stack of the present disclosure includes the above battery cells, it is easy to improve the current efficiency and reduce the reaction resistivity at the same time.
　（１０）本開示の一態様に係るレドックスフロー電池システムは、上記（１）から上記（８）のいずれか１つの電池セル、又は上記（９）のセルスタックを備える。 (10) The redox flow battery system according to one aspect of the present disclosure includes any one of the battery cells (1) to (8) above, or the cell stack according to (9) above.
　本開示のレドックスフロー電池システムは、上記電池セル又は上記セルスタックを備えるため、電流効率の向上及び反応抵抗率の低下を両立し易い。 Since the redox flow battery system of the present disclosure includes the battery cell or the cell stack, it is easy to improve the current efficiency and reduce the reaction resistivity at the same time.
　《本開示の実施形態の詳細》
　本開示の実施形態に係るレドックスフロー電池システムの詳細を、以下に説明する。図中の同一符号は同一名称物を示す。以下、レドックスフロー電池システムをＲＦ電池システムと表記することがある。 << Details of Embodiments of the present disclosure >>
Details of the redox flow battery system according to the embodiment of the present disclosure will be described below. The same reference numerals in the figures indicate the same names. Hereinafter, the redox flow battery system may be referred to as an RF battery system.
　《実施形態》
　〔ＲＦ電池システム〕
　図１から図５を参照して、実施形態のＲＦ電池システム１を説明する。ＲＦ電池システム１は、図１に示すように、電池セル１０と循環機構とを備える。電池セル１０は、正極電極１４と、負極電極１５と、隔膜１１とを有する。隔膜１１は、正極電極１４と負極電極１５との間に配置されている。循環機構は、電池セル１０に電解液を循環する。本形態のＲＦ電池システム１の特徴の一つは、正極電極１４と隔膜１１との間及び負極電極１５と隔膜１１との間の少なくとも一方の間に配置される特定の第一の層１７を備える点にある。図１は、正極電極１４と隔膜１１との間に第一の層１７が配置されている場合を示す。負極電極１５と隔膜１１との間には、第一の層１７が配置されていない。以下の説明は、ＲＦ電池システム１の概要と基本構成、本形態のＲＦ電池システム１の各構成の詳細、の順に行う。 << Embodiment >>
[RF battery system]
The RF battery system 1 of the embodiment will be described with reference to FIGS. 1 to 5. As shown in FIG. 1, the RF battery system 1 includes a battery cell 10 and a circulation mechanism. The battery cell 10 has a positive electrode 14, a negative electrode 15, and a diaphragm 11. The diaphragm 11 is arranged between the positive electrode 14 and the negative electrode 15. The circulation mechanism circulates the electrolytic solution in the battery cell 10. One of the features of the RF battery system 1 of the present embodiment is that a specific first layer 17 is arranged between the positive electrode 14 and the diaphragm 11 and at least one between the negative electrode 15 and the diaphragm 11. There is a point to prepare. FIG. 1 shows a case where the first layer 17 is arranged between the positive electrode 14 and the diaphragm 11. The first layer 17 is not arranged between the negative electrode 15 and the diaphragm 11. The following description will be given in the order of an outline and basic configuration of the RF battery system 1 and details of each configuration of the RF battery system 1 of the present embodiment.
　　［ＲＦ電池システムの概要］
　図１に示すＲＦ電池システム１は、電力を充放電する。充電電力は、発電部５１０で発電された電力である。放電電力は、負荷５３０に供給される。発電部５１０としては、例えば、太陽光発電装置、風力発電装置、又はその他一般の発電所などが挙げられる。負荷５３０としては、例えば、電力の需要家などが挙げられる。ＲＦ電池システム１は、代表的には、交流／直流変換器５００及び変電設備５２０を介して発電部５１０及び負荷５３０に接続される。図１における交流／直流変換器５００と変電設備５２０との間の実線矢印は充電を意味し、破線矢印は放電を意味する。ＲＦ電池システム１は、例えば、負荷平準化用途、瞬低補償又は非常用電源などの用途、大量導入が進められている太陽光発電又は風力発電などの自然エネルギーの出力平滑化用途などに利用される。ＲＦ電池システム１は、正極電解液及び負極電解液を使用する。正極電解液及び負極電解液は、酸化還元により価数が変化する金属イオンを活物質として含有する。ＲＦ電池システム１の充放電は、正極電解液に含まれる金属イオンの酸化還元電位と負極電解液に含まれる金属イオンの酸化還元電位との差を利用して行われる。 [Overview of RF battery system]
The RF battery system 1 shown in FIG. 1 charges and discharges electric power. The charging power is the power generated by the power generation unit 510. The discharge power is supplied to the load 530. Examples of the power generation unit 510 include a solar power generation device, a wind power generation device, and other general power plants. Examples of the load 530 include electric power consumers. The RF battery system 1 is typically connected to the power generation unit 510 and the load 530 via the AC / DC converter 500 and the substation equipment 520. The solid arrow between the AC / DC converter 500 and the substation equipment 520 in FIG. 1 means charging, and the broken line arrow means discharging. The RF battery system 1 is used, for example, for load leveling applications, applications such as instantaneous low compensation or emergency power supply, and applications for smoothing the output of natural energy such as solar power generation or wind power generation, which are being introduced in large quantities. To. The RF battery system 1 uses a positive electrode electrolytic solution and a negative electrode electrolytic solution. The positive electrode electrolytic solution and the negative electrode electrolytic solution contain metal ions whose valences change due to redox as an active material. The charging / discharging of the RF battery system 1 is performed by utilizing the difference between the redox potential of the metal ions contained in the positive electrode electrolytic solution and the redox potential of the metal ions contained in the negative electrode electrolytic solution.
　　［ＲＦ電池の基本構成］
　ＲＦ電池システム１は、電池セル１０を備える。電池セル１０は、正極セルと負極セルとを備える。正極セルと負極セルとは、後述する隔膜１１で分離されている。 [Basic configuration of RF battery]
The RF battery system 1 includes a battery cell 10. The battery cell 10 includes a positive electrode cell and a negative electrode cell. The positive electrode cell and the negative electrode cell are separated by a diaphragm 11 described later.
　正極セルには、後述する正極電極１４が内蔵されている。正極セルには、正極用循環機構１０Ｐにより正極電解液が循環する。正極用循環機構１０Ｐは、正極電解液タンク１８と、供給管２０と、排出管２２と、ポンプ２４とを備える。正極電解液タンク１８は、正極電解液を貯留する。供給管２０と排出管２２とは、正極電解液が流通する。供給管２０は、正極電解液タンク１８と正極セルとを接続する。排出管２２は、正極セルと正極電解液タンク１８とを接続する。ポンプ２４は、正極電解液タンク１８内の正極電解液を圧送する。ポンプ２４は、供給管２０の途中に設けられている。 The positive electrode cell has a built-in positive electrode 14 which will be described later. The positive electrode electrolytic solution circulates in the positive electrode cell by the positive electrode circulation mechanism 10P. The positive electrode circulation mechanism 10P includes a positive electrode electrolyte tank 18, a supply pipe 20, a discharge pipe 22, and a pump 24. The positive electrode electrolyte tank 18 stores the positive electrode electrolyte. The positive electrode electrolyte flows through the supply pipe 20 and the discharge pipe 22. The supply pipe 20 connects the positive electrode electrolyte tank 18 and the positive electrode cell. The discharge pipe 22 connects the positive electrode cell and the positive electrode electrolyte tank 18. The pump 24 pumps the positive electrode electrolyte in the positive electrode electrolyte tank 18. The pump 24 is provided in the middle of the supply pipe 20.
　負極セルには、後述する負極電極１５が内蔵されている。負極セルには、負極用循環機構１０Ｎにより負極電解液が循環する。負極用循環機構１０Ｎは、負極電解液タンク１９と、供給管２１と、排出管２３と、ポンプ２５とを備える。負極電解液タンク１９は、負極電解液を貯留する。供給管２１と排出管２３とは、負極電解液が流通する。供給管２１は、負極電解液タンク１９と負極セルとを接続する。排出管２３は、負極セルと負極電解液タンク１９とを接続する。ポンプ２５は、負極電解液タンク１９内の負極電解液を圧送する。ポンプ２５は、供給管２１の途中に設けられている。 The negative electrode cell has a built-in negative electrode 15 which will be described later. The negative electrode electrolytic solution is circulated in the negative electrode cell by the negative electrode circulation mechanism 10N. The negative electrode circulation mechanism 10N includes a negative electrode electrolyte tank 19, a supply pipe 21, a discharge pipe 23, and a pump 25. The negative electrode electrolyte tank 19 stores the negative electrode electrolyte. The negative electrode electrolyte flows through the supply pipe 21 and the discharge pipe 23. The supply pipe 21 connects the negative electrode electrolyte tank 19 and the negative electrode cell. The discharge pipe 23 connects the negative electrode cell and the negative electrode electrolyte tank 19. The pump 25 pumps the negative electrode electrolyte in the negative electrode electrolyte tank 19. The pump 25 is provided in the middle of the supply pipe 21.
　充放電が行われる運転時、ポンプ２４及びポンプ２５によって圧送された正極電解液及び負極電解液は次のように流通する。正極電解液は、供給管２０を流通して正極電解液タンク１８から正極セルに供給される。この正極電解液は、排出管２２を流通して正極セルから正極電解液タンク１８に排出される。負極電解液は、供給管２１を流通して負極電解液タンク１９から負極セルに供給される。この負極電解液は、排出管２３を流通して負極セルから負極電解液タンク１９に排出される。充放電が行われない待機時、ポンプ２４及びポンプ２５は停止している。即ち、正極電解液及び負極電解液は流通しない。 During the operation in which charging and discharging are performed, the positive electrode electrolytic solution and the negative electrode electrolytic solution pumped by the pump 24 and the pump 25 circulate as follows. The positive electrode electrolyte flows through the supply pipe 20 and is supplied from the positive electrode electrolyte tank 18 to the positive electrode cell. This positive electrode electrolyte flows through the discharge pipe 22 and is discharged from the positive electrode cell to the positive electrode electrolyte tank 18. The negative electrode electrolytic solution flows through the supply pipe 21 and is supplied from the negative electrode electrolytic solution tank 19 to the negative electrode cell. This negative electrode electrolytic solution flows through the discharge pipe 23 and is discharged from the negative electrode cell to the negative electrode electrolytic solution tank 19. The pump 24 and the pump 25 are stopped during standby when charging / discharging is not performed. That is, the positive electrode electrolyte and the negative electrode electrolyte do not circulate.
　　［第一の層］
　第一の層１７は、後述する電極１００と隔膜１１との接触を抑制する。電極１００と隔膜１１との接触が抑制されることで、電極１００と隔膜１１との接触に伴う隔膜１１の損傷が抑制される。隔膜１１の損傷の抑制により、正極電解液と負極電解液とが隔膜１１の損傷部分を介して短絡することが抑制される。短絡の抑制により、電流効率が向上する。第一の層１７は、電極１００とは別体である。第一の層１７は、正極電極１４と隔膜１１との間及び負極電極１５と隔膜１１との間の少なくとも一方の間に配置されている。第一の層１７の平面形状の一例は、矩形状である。平面形状とは、第一の層１７の第一面又は第二面を平面視したときの第一面又は第二面の輪郭形状である。第一面は、電極１００に向かい合う面である。第二面は、隔膜１１に向かい合う面である。ここでいう矩形状とは、長方形と正方形とが含まれる。この点は、後述する電極１００の平面形状及び隔膜１１の平面形状でも同様である。第一の層１７は、図３に示すように、第一繊維集合体１７１で構成されている。第一繊維集合体１７１は、複数の第一繊維１７１ａを有する。各第一繊維１７１ａは、絶縁材料からなる。 [First layer]
The first layer 17 suppresses contact between the electrode 100 and the diaphragm 11, which will be described later. By suppressing the contact between the electrode 100 and the diaphragm 11, damage to the diaphragm 11 due to the contact between the electrode 100 and the diaphragm 11 is suppressed. By suppressing damage to the diaphragm 11, it is possible to prevent the positive electrode electrolyte and the negative electrode electrolyte from being short-circuited through the damaged portion of the diaphragm 11. By suppressing short circuits, current efficiency is improved. The first layer 17 is separate from the electrode 100. The first layer 17 is arranged between the positive electrode 14 and the diaphragm 11 and between at least one of the negative electrode 15 and the diaphragm 11. An example of the planar shape of the first layer 17 is a rectangular shape. The planar shape is the contour shape of the first surface or the second surface when the first surface or the second surface of the first layer 17 is viewed in a plan view. The first surface is the surface facing the electrode 100. The second surface is the surface facing the diaphragm 11. The rectangular shape referred to here includes a rectangle and a square. This point is the same for the planar shape of the electrode 100 and the planar shape of the diaphragm 11, which will be described later. As shown in FIG. 3, the first layer 17 is composed of the first fiber aggregate 171. The first fiber assembly 171 has a plurality of first fibers 171a. Each first fiber 171a is made of an insulating material.
　　　（繊維径）
　複数の第一繊維１７１ａの平均直径は、２μｍ以上である。平均直径が２μｍ以上の第一繊維１７１ａは、第一繊維集合体１７１の強度を向上させ易い。複数の第一繊維１７１ａの平均直径が大きいほど、第一の層１７と隔膜１１との接触に伴う隔膜１１の損傷が抑制され易い。特に、第一繊維１７１ａの平均直径は、電極１００を構成する第二繊維１１１ａの平均直径と同様、もしくは大きいことが好ましい。第一繊維１７１ａの平均直径が第二繊維１１１ａよりも大きければ、第一の層１７と隔膜１１との接触に伴う隔膜１１の損傷が抑制され易い。複数の第一繊維１７１ａの平均直径は、更に５μｍ以上が挙げられ、特に８μｍ以上が挙げられる。 (Fiber diameter)
The average diameter of the plurality of first fibers 171a is 2 μm or more. The first fiber 171a having an average diameter of 2 μm or more tends to improve the strength of the first fiber aggregate 171. The larger the average diameter of the plurality of first fibers 171a, the easier it is to suppress the damage to the diaphragm 11 due to the contact between the first layer 17 and the diaphragm 11. In particular, the average diameter of the first fiber 171a is preferably the same as or larger than the average diameter of the second fiber 111a constituting the electrode 100. When the average diameter of the first fiber 171a is larger than that of the second fiber 111a, damage to the diaphragm 11 due to contact between the first layer 17 and the diaphragm 11 is likely to be suppressed. The average diameter of the plurality of first fibers 171a may be further 5 μm or more, and particularly 8 μm or more.
　複数の第一繊維１７１ａの平均直径は、５０μｍ以下である。平均直径が５０μｍ以下の第一繊維１７１ａは、剛性が小さく、第一の層１７と隔膜１１との接触に伴う隔膜１１の損傷が抑制され易い。複数の第一繊維１７１ａの平均直径は、更に３０μｍ以下が挙げられ、特に２０μｍ以下が挙げられる。 The average diameter of the plurality of first fibers 171a is 50 μm or less. The first fiber 171a having an average diameter of 50 μm or less has low rigidity, and damage to the diaphragm 11 due to contact between the first layer 17 and the diaphragm 11 is likely to be suppressed. The average diameter of the plurality of first fibers 171a may be further 30 μm or less, and particularly 20 μm or less.
　即ち、複数の第一繊維１７１ａの平均直径は、２μｍ以上５０μｍ以下が挙げられ、更に５μｍ以上３０μｍ以下が挙げられ、特に８μｍ以上２０μｍ以下が挙げられる。 That is, the average diameter of the plurality of first fibers 171a is 2 μm or more and 50 μm or less, further 5 μm or more and 30 μm or less, and particularly 8 μm or more and 20 μm or less.
　複数の第一繊維１７１ａの平均直径は、次のようにして求められる。第一の層１７を切断して第一繊維１７１ａの断面を露出させる。第一の層１７の切断は、第一の層１７の厚さ方向に行われる。断面をマイクロスコープで拡大する。マイクロスコープの倍率は、１０００倍とする。５本以上の第一繊維１７１ａについて、各第一繊維１７１ａの直径を求める。上記直径は、第一繊維１７１ａの断面の面積と同じ面積を有する円の直径である。求めた全ての円の直径を平均する。 The average diameter of the plurality of first fibers 171a is obtained as follows. The first layer 17 is cut to expose the cross section of the first fiber 171a. The cutting of the first layer 17 is performed in the thickness direction of the first layer 17. Enlarge the cross section with a microscope. The magnification of the microscope is 1000 times. For five or more first fibers 171a, the diameter of each first fiber 171a is determined. The diameter is the diameter of a circle having the same area as the cross-sectional area of the first fiber 171a. Average the diameters of all the circles found.
　　　（ヤング率）
　複数の第一繊維１７１ａの平均ヤング率は、例えば、２００ＧＰａ以下が挙げられる。複数の第一繊維１７１ａの平均ヤング率が２００ＧＰａ以下であることで、第一繊維集合体１７１は、第一の層１７と隔膜１１との接触に伴う隔膜１１の損傷を抑制し易い。特に、複数の第一繊維１７１ａの平均ヤング率は、電極１００を構成する第二繊維１１１ａのヤング率よりも小さいことが好ましい。複数の第一繊維１７１ａの平均ヤング率が複数の第二繊維１１１ａの平均ヤング率よりも小さければ、第一の層１７と隔膜１１との接触に伴う隔膜１１の損傷が抑制され易い。複数の第一繊維１７１ａの平均ヤング率は、更に１５０ＧＰａ以下、１００ＧＰａ以下が挙げられ、特に１０ＧＰａ以下が挙げられる。 (Young's modulus)
The average Young's modulus of the plurality of first fibers 171a is, for example, 200 GPa or less. When the average Young's modulus of the plurality of first fibers 171a is 200 GPa or less, the first fiber aggregate 171 can easily suppress damage to the diaphragm 11 due to contact between the first layer 17 and the diaphragm 11. In particular, the average Young's modulus of the plurality of first fibers 171a is preferably smaller than the Young's modulus of the second fibers 111a constituting the electrode 100. When the average Young's modulus of the plurality of first fibers 171a is smaller than the average Young's modulus of the plurality of second fibers 111a, damage to the diaphragm 11 due to contact between the first layer 17 and the diaphragm 11 is likely to be suppressed. Further, the average Young's modulus of the plurality of first fibers 171a is 150 GPa or less, 100 GPa or less, and particularly 10 GPa or less.
　複数の第一繊維１７１ａの平均ヤング率の下限は、例えば、１００ＭＰａが挙げられる。複数の第一繊維１７１ａは、平均ヤング率が１００ＭＰａ以上であることで、第一繊維集合体１７１の強度を向上させ易い。 The lower limit of the average Young's modulus of the plurality of first fibers 171a is, for example, 100 MPa. Since the average Young's modulus of the plurality of first fibers 171a is 100 MPa or more, the strength of the first fiber aggregate 171 can be easily improved.
　即ち、複数の第一繊維１７１ａの平均ヤング率は、１００ＭＰａ以上２００ＧＰａ以下、更に１００ＭＰａ以上１５０ＧＰａ以下、３００ＭＰａ以上１００ＧＰａ以下、特に５００ＭＰａ以上１０ＧＰａ以下が挙げられる。 That is, the average Young's modulus of the plurality of first fibers 171a is 100 MPa or more and 200 GPa or less, further 100 MPa or more and 150 GPa or less, 300 MPa or more and 100 GPa or less, and particularly 500 MPa or more and 10 GPa or less.
　複数の第一繊維１７１ａの平均ヤング率は、５本以上の第一繊維１７１ａのヤング率を平均した値である。 The average Young's modulus of the plurality of first fibers 171a is a value obtained by averaging the Young's modulus of five or more first fibers 171a.
　　　（材質）
　第一繊維１７１ａを構成する絶縁材料は、例えば、樹脂、又はセラミックスが挙げられる。樹脂は、ポリフェニレンスルフィド、ポリエチレン、ポリプロピレン、ポリアミド、ポリ塩化ビニル、ポリスチレン、ポリブチレンサクシネート、アクリル、ポリテトラフルオロエチレン、テトラフルオロエチレン・エチレン共重合体、ポリカーボネート、フェノール、又はエポキシが挙げられる。樹脂は、特にポリフェニレンスルフィドが挙げられる。セラミックスは、シリカ、アルミナ、ジルコニア、又は炭化ケイ素が挙げられる。 (Material)
Examples of the insulating material constituting the first fiber 171a include resin and ceramics. Examples of the resin include polyphenylene sulfide, polyethylene, polypropylene, polyamide, polyvinyl chloride, polystyrene, polybutylene succinate, acrylic, polytetrafluoroethylene, tetrafluoroethylene / ethylene copolymer, polycarbonate, phenol, and epoxy. Examples of the resin include polyphenylene sulfide. Examples of the ceramics include silica, alumina, zirconia, and silicon carbide.
　樹脂からなる第一繊維１７１ａによって構成された第一繊維集合体１７１は、セラミックスからなる第一繊維１７１ａによって構成された第一繊維集合体１７１よりも、第一の層１７と隔膜１１との接触に伴う隔膜１１の損傷を抑制し易い。一般的に、樹脂からなる第一繊維１７１ａは、セラミックスからなる第一繊維１７１ａよりも、柔らかいからである。セラミックスからなる第一繊維１７１ａによって構成された第一繊維集合体１７１は、樹脂からなる第一繊維１７１ａによって構成された第一繊維集合体１７１よりも、電解液を拡散させ易い。セラミックスからなる第一繊維１７１ａは、樹脂からなる第一繊維１７１ａよりも、第一繊維集合体１７１の強度を向上させ易いため、第一繊維１７１ａの本数を減らし易いからである。即ち、セラミックスからなる第一繊維１７１ａは、樹脂からなる第一繊維１７１ａよりも、第一繊維集合体１７１の空隙率を高め易いからである。 The first fiber assembly 171 made of the first fiber 171a made of resin is in contact with the first layer 17 and the diaphragm 11 more than the first fiber assembly 171 made of the first fiber 171a made of ceramics. It is easy to suppress the damage of the diaphragm 11 due to the above. This is because, in general, the first fiber 171a made of resin is softer than the first fiber 171a made of ceramics. The first fiber aggregate 171 made of the first fiber 171a made of ceramics is easier to diffuse the electrolytic solution than the first fiber aggregate 171 made of the first fiber 171a made of resin. This is because the first fiber 171a made of ceramics is easier to improve the strength of the first fiber aggregate 171 than the first fiber 171a made of resin, so that the number of first fibers 171a can be easily reduced. That is, the first fiber 171a made of ceramics is easier to increase the porosity of the first fiber aggregate 171 than the first fiber 171a made of resin.
　特に、第一繊維１７１ａを構成する絶縁材料は、電極１００を構成する第二繊維１１１ａの構成材料よりも柔らかい材料であることが好ましい。柔らかい材料で構成される第一繊維１７１ａは、第一の層１７と隔膜１１との接触に伴う隔膜１１の損傷を抑制し易い。 In particular, the insulating material constituting the first fiber 171a is preferably a material softer than the constituent material of the second fiber 111a constituting the electrode 100. The first fiber 171a made of a soft material can easily suppress damage to the diaphragm 11 due to contact between the first layer 17 and the diaphragm 11.
　第一繊維１７１ａの材質は、Ｘ線回折により求められる。 The material of the first fiber 171a is obtained by X-ray diffraction.
　　　（空隙率）
　第一繊維集合体１７１の空隙率Ｐ１は、２０％以上９９％以下である。第一繊維集合体１７１の空隙率Ｐ１は、圧縮状態の第一繊維集合体１７１の空隙率である。圧縮状態とは、電池セル１０又は後述するセルスタック２００を組み立てた後の状態をいう。空隙率Ｐ１が２０％以上の第一繊維集合体１７１は、電解液を拡散し易い。空隙率Ｐ１が９９％以下の第一繊維集合体１７１は、電極１００を構成する第二繊維１１１ａが第一繊維集合体１７１の空隙を通って隔膜１１に突き刺さることを抑制し易い。そのため、隔膜１１の損傷が抑制される。また、空隙率Ｐ１が９９％以下の第一繊維集合体１７１は、第一繊維集合体１７１の形状を保持し易い。第一繊維集合体１７１の空隙率Ｐ１は、更に２５％以上９９％以下、３０％以上９５％以下が挙げられ、特に３５％以上９０％以下が挙げられる。第一繊維集合体１７１の空隙率Ｐ１は、電極１００の空隙率よりも大きいことが好ましい。電極１００の空隙率よりも大きい空隙率Ｐ１を有する第一繊維集合体１７１は、隔膜１１との接触に伴う隔膜１１の損傷を抑制し易い。 (Porosity)
The porosity P 1 of the first fiber aggregate 171 is 20% or more and 99% or less. The porosity P1 of the first fiber aggregate 171 is the porosity of the first fiber aggregate 171 in the compressed state. The compressed state refers to a state after assembling the battery cell 10 or the cell stack 200 described later. The first fiber aggregate 171 having a porosity P 1 of 20% or more easily diffuses the electrolytic solution. The first fiber aggregate 171 having a porosity P1 of 99% or less can easily prevent the second fibers 111a constituting the electrode 100 from penetrating the diaphragm 11 through the voids of the first fiber aggregate 171. Therefore, damage to the diaphragm 11 is suppressed. Further, the first fiber aggregate 171 having a porosity P1 of 99% or less easily retains the shape of the first fiber aggregate 171. The porosity P 1 of the first fiber aggregate 171 is further referred to as 25% or more and 99% or less, 30% or more and 95% or less, and particularly 35% or more and 90% or less. The porosity P 1 of the first fiber assembly 171 is preferably larger than the porosity of the electrode 100. The first fiber aggregate 171 having a porosity P 1 larger than the porosity of the electrode 100 can easily suppress damage to the diaphragm 11 due to contact with the diaphragm 11.
　第一繊維集合体１７１の空隙率Ｐ１は、Ｐ１＝１００－｛（１００－Ｐ０）ｄ０／ｄ１｝で求められる。Ｐ０は、非圧縮状態の電極１００の空隙率である。非圧縮状態の電極１００の空隙率Ｐ０は、水銀圧入法により求められる。ｄ０は、非圧縮状態の第一繊維集合体１７１の厚さである。ｄ１は、圧縮状態の第一繊維集合体１７１の厚さである。圧縮状態の第一繊維集合体１７１の厚さｄ１は、圧縮試験で求められる。圧縮試験では、電池セル１０又は後述するセルスタック２００を組み立てた後の状態で第一繊維集合体１７１に作用する圧力と同等の圧力を第一繊維集合体１７１に作用させる。厚さｄ０及び厚さｄ１は、５箇所以上の厚さの平均値とする。厚さｄ０及び厚さｄ１の測定箇所の一例は、図５に示すように、少なくとも第一交点Ｃ１から第五交点Ｃ５である。図５は、第一繊維集合体１７１の平面形状が長方形である場合を例示している。図５では、長方形の短辺の長さを幅Ｗａとし、長方形の長辺の長さを長さＬａとしている。 The porosity P 1 of the first fiber assembly 171 is determined by P 1 = 100-{(100-P 0 ) d 0 / d 1 }. P 0 is the porosity of the electrode 100 in the uncompressed state. The porosity P0 of the electrode 100 in the uncompressed state is determined by the mercury intrusion method. d 0 is the thickness of the first fiber assembly 171 in the uncompressed state. d 1 is the thickness of the first fiber assembly 171 in the compressed state. The thickness d 1 of the first fiber assembly 171 in the compressed state is determined by a compression test. In the compression test, a pressure equivalent to the pressure acting on the first fiber assembly 171 is applied to the first fiber assembly 171 in a state after the battery cell 10 or the cell stack 200 described later is assembled. The thickness d 0 and the thickness d 1 are the average values of the thicknesses of five or more places. As shown in FIG. 5, an example of the measurement points of the thickness d 0 and the thickness d 1 is at least the first intersection C1 to the fifth intersection C5. FIG. 5 illustrates a case where the planar shape of the first fiber assembly 171 is rectangular. In FIG. 5, the length of the short side of the rectangle is the width Wa, and the length of the long side of the rectangle is the length La.
　第一交点Ｃ１は、第一仮想線Ｖ１と第三仮想線Ｖ３との交点である。
　第二交点Ｃ２は、第一仮想線Ｖ１と第四仮想線Ｖ４との交点である。
　第三交点Ｃ３は、第二仮想線Ｖ２と第三仮想線Ｖ３との交点である。
　第四交点Ｃ４は、第二仮想線Ｖ２と第四仮想線Ｖ４との交点である。
　第五交点Ｃ５は、対角線Ｄ１、Ｄ２同士の交点である。 The first intersection C1 is the intersection of the first virtual line V1 and the third virtual line V3.
The second intersection C2 is the intersection of the first virtual line V1 and the fourth virtual line V4.
The third intersection C3 is the intersection of the second virtual line V2 and the third virtual line V3.
The fourth intersection C4 is the intersection of the second virtual line V2 and the fourth virtual line V4.
The fifth intersection C5 is the intersection of the diagonal lines D1 and D2.
　第一仮想線Ｖ１は、第一繊維集合体１７１の短辺方向に沿った直線であって、第一繊維集合体１７１の第一短辺から第一仮想線Ｖ１までの距離が長さＬａ×０．１倍以上長さＬａ×０．２倍以下となる直線である。
　第二仮想線Ｖ２は、第一繊維集合体１７１の短辺方向に沿った直線であって、第一繊維集合体１７１の第二短辺から第二仮想線Ｖ２までの距離が長さＬａ×０．１倍以上長さＬａ×０．２倍以下となる直線である。
　第一短辺から第一仮想線Ｖ１までの距離と第二短辺から第二仮想線Ｖ２までの距離とは同一とする。
　第三仮想線Ｖ３は、第一繊維集合体１７１の長辺方向に沿った直線であって、第一繊維集合体１７１の第一長辺から第三仮想線Ｖ３までの距離が幅Ｗａ×０．１倍以上幅Ｗａ×０．２倍以下となる直線である。
　第四仮想線Ｖ４は、第一繊維集合体１７１の長辺方向に沿った直線であって、第一繊維集合体１７１の第二長辺から第四仮想線Ｖ４までの距離が幅Ｗａ×０．１倍以上幅Ｗａ×０．２倍以下となる直線である。
　第一長辺から第三仮想線Ｖ３までの距離と第二長辺から第四仮想線Ｖ４までの距離とは同一とする。 The first virtual line V1 is a straight line along the short side direction of the first fiber assembly 171 and the distance from the first short side of the first fiber assembly 171 to the first virtual line V1 is the length La ×. It is a straight line having a length of 0.1 times or more and La × 0.2 times or less.
The second virtual line V2 is a straight line along the short side direction of the first fiber assembly 171 and the distance from the second short side of the first fiber assembly 171 to the second virtual line V2 is the length La ×. It is a straight line having a length of 0.1 times or more and La × 0.2 times or less.
The distance from the first short side to the first virtual line V1 and the distance from the second short side to the second virtual line V2 are the same.
The third virtual line V3 is a straight line along the long side direction of the first fiber assembly 171 and the distance from the first long side of the first fiber assembly 171 to the third virtual line V3 is width Wa × 0. . It is a straight line having a width of 1 times or more and a width of Wa × 0.2 times or less.
The fourth virtual line V4 is a straight line along the long side direction of the first fiber assembly 171 and the distance from the second long side of the first fiber assembly 171 to the fourth virtual line V4 is width Wa × 0. . It is a straight line having a width of 1 times or more and a width of Wa × 0.2 times or less.
The distance from the first long side to the third virtual line V3 and the distance from the second long side to the fourth virtual line V4 are the same.
　測定箇所の数を増やす場合、以下の要件（ａ）及び要件（ｂ）の少なくとも一方を満たすとよい。
　（ａ）第一仮想線Ｖ１と第二仮想線Ｖ２との間を均等に分割して、第三仮想線Ｖ３と第四仮想線Ｖ４とに交差する１本以上の追加の仮想線をとる。
　（ｂ）第三仮想線Ｖ３と第四仮想線Ｖ４との間を均等に分割して、第一仮想線Ｖ１と第二仮想線Ｖ２とに交差する１本以上の追加の仮想線をとる。
　上記要件（ａ）の場合、第三仮想線Ｖ３上における第一交点Ｃ１と第三交点Ｃ３との間に１つ以上の追加の交点が並び、第四仮想線Ｖ４上における第二交点Ｃ２と第四交点Ｃ４との間に１つ以上の追加の交点が並ぶ。第三仮想線Ｖ３上における追加の交点の数と第四仮想線Ｖ４上における追加の交点の数とは同数である。第三仮想線Ｖ３上における追加の交点と第一交点Ｃ１と第三交点Ｃ３とは、等間隔に並ぶ。第四仮想線Ｖ４上における追加の交点と第二交点Ｃ２と第四交点Ｃ４とは、等間隔に並ぶ。
　上記要件（ｂ）の場合、第一仮想線Ｖ１上における第一交点Ｃ１と第二交点Ｃ２との間に１つ以上の追加の交点が並び、第二仮想線Ｖ２上における第三交点Ｃ３と第四交点Ｃ４との間に１つ以上の追加の交点が並ぶ。第一仮想線Ｖ１上における追加の交点の数と第二仮想線Ｖ２上における追加の交点の数とは同数である。第一仮想線Ｖ１上における追加の交点と第一交点Ｃ１と第二交点Ｃ２とは、等間隔に並ぶ。第二仮想線Ｖ２上における追加の交点と第三交点Ｃ３と第四交点Ｃ４とは等間隔に並ぶ。 When increasing the number of measurement points, it is preferable to satisfy at least one of the following requirements (a) and (b).
(A) The first virtual line V1 and the second virtual line V2 are evenly divided, and one or more additional virtual lines intersecting the third virtual line V3 and the fourth virtual line V4 are taken.
(B) The third virtual line V3 and the fourth virtual line V4 are evenly divided, and one or more additional virtual lines intersecting the first virtual line V1 and the second virtual line V2 are taken.
In the case of the above requirement (a), one or more additional intersections are lined up between the first intersection C1 and the third intersection C3 on the third virtual line V3, and the second intersection C2 on the fourth virtual line V4. One or more additional intersections are lined up with the fourth intersection C4. The number of additional intersections on the third virtual line V3 and the number of additional intersections on the fourth virtual line V4 are the same. The additional intersections on the third virtual line V3, the first intersection C1 and the third intersection C3 are arranged at equal intervals. The additional intersections on the fourth virtual line V4, the second intersection C2, and the fourth intersection C4 are arranged at equal intervals.
In the case of the above requirement (b), one or more additional intersections are arranged between the first intersection C1 and the second intersection C2 on the first virtual line V1 and the third intersection C3 on the second virtual line V2. One or more additional intersections are lined up with the fourth intersection C4. The number of additional intersections on the first virtual line V1 and the number of additional intersections on the second virtual line V2 are the same. The additional intersections on the first virtual line V1, the first intersection C1 and the second intersection C2 are arranged at equal intervals. The additional intersections on the second virtual line V2, the third intersection C3, and the fourth intersection C4 are arranged at equal intervals.
　　　（目付量）
　第一繊維集合体１７１の目付量は、例えば、５ｇ／ｍ２以上１００ｇ／ｍ２以下が挙げられる。目付量が５ｇ／ｍ２以上の第一繊維集合体１７１は、電極１００を構成する第二繊維１１１ａが第一繊維集合体１７１の空隙を通って隔膜１１に突き刺さることを抑制し易い。その上、目付量が５ｇ／ｍ２以上の第一繊維集合体１７１は、第一繊維１７１ａが隔膜１１に突き刺さることを抑制し易い。目付量が１００ｇ／ｍ２以下の第一繊維集合体１７１は、電解液を拡散させ易い。第一繊維集合体１７１の目付量は、更に８ｇ／ｍ２以上５０ｇ／ｍ２以下が挙げられ、特に１０ｇ／ｍ２以上３０ｇ／ｍ２以下が挙げられる。 (Metsuke amount)
The basis weight of the first fiber aggregate 171 is, for example, 5 g / m 2 or more and 100 g / m 2 or less. The first fiber aggregate 171 having a basis weight of 5 g / m 2 or more can easily prevent the second fibers 111a constituting the electrode 100 from penetrating the diaphragm 11 through the voids of the first fiber aggregate 171. Moreover, the first fiber aggregate 171 having a basis weight of 5 g / m 2 or more easily suppresses the first fiber 171a from sticking to the diaphragm 11. The first fiber aggregate 171 having a basis weight of 100 g / m 2 or less easily diffuses the electrolytic solution. The basis weight of the first fiber aggregate 171 is further 8 g / m 2 or more and 50 g / m 2 or less, and particularly 10 g / m 2 or more and 30 g / m 2 or less.
　　　（厚さ）
　第一繊維集合体１７１の厚さは、例えば、５μｍ以上３０００μｍ以下が挙げられる。第一繊維集合体１７１の厚さは、上述した圧縮状態の第一繊維集合体１７１の厚さｄ１である。即ち、第一繊維集合体１７１の厚さは、図５を参照して上述した通りの測定方法によって求められる。厚さが５μｍ以上の第一繊維集合体１７１は、電極１００の第二繊維１１１ａが第一繊維集合体１７１の空隙を通って隔膜１１に突き刺さることを抑制し易い。第一繊維集合体１７１の厚さが５μｍ以上であっても、第一繊維集合体１７１は、上述の空隙率Ｐ１を満たすことで、電解液を拡散させ易い。厚さが３０００μｍ以下の第一繊維集合体１７１は、電解液を拡散させ易い。第一繊維集合体１７１の厚さは、更に８μｍ以上２００μｍ以下が挙げられ、特に１０μｍ以上１００μｍ以下が挙げられる。第一繊維集合体１７１の厚さは、５箇所以上の厚さの平均値とする。 (thickness)
The thickness of the first fiber assembly 171 is, for example, 5 μm or more and 3000 μm or less. The thickness of the first fiber assembly 171 is the thickness d 1 of the first fiber assembly 171 in the compressed state described above. That is, the thickness of the first fiber assembly 171 is determined by the measurement method as described above with reference to FIG. The first fiber assembly 171 having a thickness of 5 μm or more can easily prevent the second fiber 111a of the electrode 100 from penetrating the diaphragm 11 through the voids of the first fiber assembly 171. Even if the thickness of the first fiber aggregate 171 is 5 μm or more, the first fiber aggregate 171 easily diffuses the electrolytic solution by satisfying the above - mentioned porosity P1. The first fiber aggregate 171 having a thickness of 3000 μm or less easily diffuses the electrolytic solution. The thickness of the first fiber assembly 171 is further 8 μm or more and 200 μm or less, and particularly 10 μm or more and 100 μm or less. The thickness of the first fiber assembly 171 is the average value of the thicknesses of five or more places.
　　　（密度）
　第一繊維集合体１７１の密度は、例えば、０．１ｇ／ｃｍ３以上１．２ｇ／ｃｍ３以下が挙げられる。密度が０．１ｇ／ｃｍ３以上の第一繊維集合体１７１は、電極１００の第二繊維１１１ａが第一繊維集合体１７１の空隙を通って隔膜１１に突き刺さることを抑制し易い。密度が１．２ｇ／ｃｍ３以下の第一繊維集合体１７１は、電解液を拡散させ易い。第一繊維集合体１７１の密度は、更に０．１ｇ／ｃｍ３以上１．０ｇ／ｃｍ３以下、０．２ｇ／ｃｍ３以上０．９５ｇ／ｃｍ３以下が挙げられ、特０．３ｇ／ｃｍ３以上０．９ｇ／ｃｍ３以下が挙げられる。第一繊維集合体１７１の密度は、第一繊維集合体１７１の目付量を第一繊維集合体１７１の厚さで除することで求められる。ここでいう第一繊維集合体１７１の厚さとは、上述した通り、圧縮状態の第一繊維集合体１７１の厚さｄ１である。 (density)
The density of the first fiber assembly 171 is, for example, 0.1 g / cm 3 or more and 1.2 g / cm 3 or less. The first fiber assembly 171 having a density of 0.1 g / cm 3 or more can easily prevent the second fiber 111a of the electrode 100 from penetrating the diaphragm 11 through the voids of the first fiber assembly 171. The first fiber aggregate 171 having a density of 1.2 g / cm 3 or less easily diffuses the electrolytic solution. The density of the first fiber aggregate 171 is 0.1 g / cm 3 or more and 1.0 g / cm 3 or less, 0.2 g / cm 3 or more and 0.95 g / cm 3 or less, and is particularly 0.3 g / cm. 3 or more and 0.9 g / cm 3 or less can be mentioned. The density of the first fiber aggregate 171 is obtained by dividing the basis weight of the first fiber aggregate 171 by the thickness of the first fiber aggregate 171. As described above, the thickness of the first fiber aggregate 171 referred to here is the thickness d 1 of the first fiber aggregate 171 in the compressed state.
　　［正極電極・負極電極］
　正極電極１４及び負極電極１５は、電池反応を行う場である。正極電極１４と負極電極１５とは、互いに同一の電極を用いてもよいし、互いに異なる電極を用いてもよい。正極電極１４及び負極電極１５のうち、第一の層１７に隣り合う電極は、電極１００で構成されている。正極電極１４及び負極電極１５のうち、第一の層１７に隣り合わない電極は、電極１００で構成されていてもよいし、電極１００とは異なる電極で構成されていてもよい。電極１００とは異なる電極は、公知の電極が利用できる。電極１００の平面形状の一例は、矩形状である。平面形状とは、電極１００の第一面又は第二面を電極１００の厚さ方向から見たときの形状である。第一面は、後述する双極板１６１に向かい合う面である。第二面は、第一の層１７又は隔膜１１に向かい合う面である。 [Positive electrode / Negative electrode]
The positive electrode 14 and the negative electrode 15 are places where a battery reaction is performed. The positive electrode 14 and the negative electrode 15 may use the same electrodes or different electrodes from each other. Of the positive electrode 14 and the negative electrode 15, the electrode adjacent to the first layer 17 is composed of the electrode 100. Of the positive electrode 14 and the negative electrode 15, the electrodes that are not adjacent to the first layer 17 may be composed of the electrode 100 or may be composed of an electrode different from the electrode 100. As an electrode different from the electrode 100, a known electrode can be used. An example of the planar shape of the electrode 100 is a rectangular shape. The planar shape is a shape when the first surface or the second surface of the electrode 100 is viewed from the thickness direction of the electrode 100. The first surface is a surface facing the bipolar plate 161 described later. The second surface is the surface facing the first layer 17 or the diaphragm 11.
　電極１００は、多孔質材料で構成される。多孔質材料の具体例として、図４に示すように、第二繊維集合体１１１が挙げられる。第二繊維集合体１１１は、導電材料からなる複数の第二繊維１１１ａを有する。第一の層１７によって電極１００と隔膜１１との接触が抑制され易いため、電極１００が第二繊維集合体１１１であっても、電流効率の低下が抑制され易い。第二繊維集合体１１１は、第二繊維１１１ａ同士の接点を多くし易い。そのため、第二繊維集合体１１１で構成される電極１００は、導電性を向上し易い。また、第二繊維集合体１１１は、空隙を確保し易い。そのため、第二繊維集合体１１１で構成される電極１００は、電解液の流通性を向上し易い。第二繊維集合体１１１は、不織布、織布、又はペーパーが挙げられる。不織布は、独立した第二繊維１１１ａを交絡させたものである。織布は、第二繊維１１１ａの縦糸と横糸とを交互に織り合わせたものである。ペーパーは、複数の第二繊維１１１ａと、第二繊維１１１ａを結着するバインダーとを有するものである。不織布には、フェルト、スパンレース、マリフリースなどが含まれる。 The electrode 100 is made of a porous material. As a specific example of the porous material, as shown in FIG. 4, a second fiber assembly 111 can be mentioned. The second fiber assembly 111 has a plurality of second fibers 111a made of a conductive material. Since the contact between the electrode 100 and the diaphragm 11 is easily suppressed by the first layer 17, even if the electrode 100 is the second fiber aggregate 111, the decrease in current efficiency is easily suppressed. The second fiber assembly 111 tends to increase the number of contacts between the second fibers 111a. Therefore, the electrode 100 composed of the second fiber assembly 111 tends to improve the conductivity. Further, the second fiber assembly 111 can easily secure a gap. Therefore, the electrode 100 composed of the second fiber assembly 111 tends to improve the flowability of the electrolytic solution. Examples of the second fiber assembly 111 include non-woven fabric, woven fabric, and paper. The non-woven fabric is made by entwining independent second fibers 111a. The woven fabric is made by alternately weaving the warp and weft of the second fiber 111a. The paper has a plurality of second fibers 111a and a binder for binding the second fibers 111a. Nonwoven fabrics include felt, spunlace, marifleece and the like.
　　　（繊維径）
　複数の第二繊維１１１ａの平均直径は、例えば、１μｍ以上２０μｍ以下が挙げられる。平均直径が１μｍ以上の第二繊維１１１ａは、第二繊維集合体１１１の強度を高め易い。平均直径が２０μｍ以下の第二繊維１１１ａは、単位重量当たりの第二繊維１１１ａの表面積が大きいため、電池反応性を向上させ易い。複数の第二繊維１１１ａの平均直径は、更に５μｍ以上１８μｍ以下が挙げられ、特に８μｍ以上１５μｍ以下が挙げられる。複数の第二繊維１１１ａの平均直径の求め方は、複数の第一繊維１７１ａの平均直径の求め方と同様である。 (Fiber diameter)
The average diameter of the plurality of second fibers 111a is, for example, 1 μm or more and 20 μm or less. The second fiber 111a having an average diameter of 1 μm or more tends to increase the strength of the second fiber assembly 111. Since the second fiber 111a having an average diameter of 20 μm or less has a large surface area of the second fiber 111a per unit weight, it is easy to improve the battery reactivity. Further, the average diameter of the plurality of second fibers 111a is 5 μm or more and 18 μm or less, and particularly 8 μm or more and 15 μm or less. The method of obtaining the average diameter of the plurality of second fibers 111a is the same as the method of obtaining the average diameter of the plurality of first fibers 171a.
　　　（ヤング率）
　複数の第二繊維１１１ａの平均ヤング率は、例えば、２００ＧＰａ以上が挙げられる。複数の第二繊維１１１ａの平均ヤング率が２００ＧＰａ以上であっても、第一の層１７によって、電極１００と隔膜１１との接触に伴う隔膜１１の損傷が抑制され易い。複数の第二繊維１１１ａの平均ヤング率は、更に２５０ＧＰａ以上が挙げられ、特に３００ＧＰａ以上が挙げられる。複数の第二繊維１１１ａの平均ヤング率の上限は、例えば、５００ＧＰａが挙げられる。複数の第二繊維１１１ａの平均ヤング率は、更に４５０ＧＰａ以下が挙げられ、特に４００ＧＰａ以下が挙げられる。即ち、複数の第二繊維１１１ａの平均ヤング率は、２００ＧＰａ以上５００ＧＰａ以下、更に２５０ＧＰａ以上４５０ＧＰａ以下、特に３００ＧＰａ以上４００ＧＰａ以下が挙げられる。複数の第二繊維１１１ａの平均ヤング率の求め方は、複数の第一繊維１７１ａの平均ヤング率の求め方と同様である。 (Young's modulus)
The average Young's modulus of the plurality of second fibers 111a is, for example, 200 GPa or more. Even if the average Young's modulus of the plurality of second fibers 111a is 200 GPa or more, the first layer 17 tends to suppress damage to the diaphragm 11 due to contact between the electrode 100 and the diaphragm 11. The average Young's modulus of the plurality of second fibers 111a further includes 250 GPa or more, and particularly 300 GPa or more. The upper limit of the average Young's modulus of the plurality of second fibers 111a is, for example, 500 GPa. Further, the average Young's modulus of the plurality of second fibers 111a is 450 GPa or less, and in particular, 400 GPa or less. That is, the average Young's modulus of the plurality of second fibers 111a is 200 GPa or more and 500 GPa or less, further 250 GPa or more and 450 GPa or less, and particularly 300 GPa or more and 400 GPa or less. The method of obtaining the average Young's modulus of the plurality of second fibers 111a is the same as the method of obtaining the average Young's modulus of the plurality of first fibers 171a.
　　　（材質）
　第二繊維１１１ａは、例えば、炭素繊維が挙げられる。炭素繊維は、電池反応性を向上し易い。炭素繊維は、例えば、ピッチ系炭素繊維、又はＰＡＮ（ポリアクリロニトリル）系炭素繊維が挙げられる。ピッチ系炭素繊維は、石油ピッチ又は石炭ピッチを原料とする。ＰＡＮ系炭素繊維は、ポリアクリロニトリルを原料とする。これらの炭素繊維の剛性は、比較的高い。これらの炭素繊維を複数有する第二繊維集合体１１１で構成される電極１００であっても、第一の層１７によって、電極１００と隔膜１１との接触に伴う隔膜１１の損傷が抑制され易い。 (Material)
Examples of the second fiber 111a include carbon fibers. Carbon fiber tends to improve battery reactivity. Examples of the carbon fiber include pitch-based carbon fiber and PAN (polyacrylonitrile) -based carbon fiber. Pitch-based carbon fibers are made from petroleum pitch or coal pitch. The PAN-based carbon fiber is made from polyacrylonitrile. The rigidity of these carbon fibers is relatively high. Even in the electrode 100 composed of the second fiber aggregate 111 having a plurality of these carbon fibers, the first layer 17 tends to suppress the damage of the diaphragm 11 due to the contact between the electrode 100 and the diaphragm 11.
　　　（バインダー）
　電極１００は、図示を省略するものの、第二繊維１１１ａ同士を結着するバインダーを有していてもよい。バインダーを有する電極１００のヤング率は、バインダーを有さない電極１００に比較して、大きくなり易い。バインダーを有する電極１００であっても、第一の層１７によって、電極１００と隔膜１１との接触に伴う隔膜１１の損傷が抑制され易い。 (binder)
Although not shown, the electrode 100 may have a binder that binds the second fibers 111a to each other. The Young's modulus of the electrode 100 having a binder tends to be larger than that of the electrode 100 having no binder. Even in the electrode 100 having a binder, the first layer 17 tends to suppress damage to the diaphragm 11 due to contact between the electrode 100 and the diaphragm 11.
　バインダーの材質は、電解液に対して溶解し難い材質が挙げられる。バインダーは、樹脂、金属、炭化物、及び金属酸化物からなる群より選択される１種以上を含む。これらの材質を含むバインダーは、第二繊維１１１ａ同士を強固に固定し易い。樹脂としては、例えば、フェノール、ポリテトラフルオロエチレン、ポリフッ化ビニリデンが挙げられる。金属としては、例えば、Ｔｉ（チタン）、Ｗ（タングステン）が挙げられる。炭化物としては、例えば、炭化チタン、炭化マンガン、炭化タングステンが挙げられる。金属酸化物としては、例えば、アルミナ、酸化スズが挙げられる。 The material of the binder includes a material that is difficult to dissolve in the electrolytic solution. The binder contains one or more selected from the group consisting of resins, metals, carbides, and metal oxides. A binder containing these materials can easily firmly fix the second fibers 111a to each other. Examples of the resin include phenol, polytetrafluoroethylene, and polyvinylidene fluoride. Examples of the metal include Ti (titanium) and W (tungsten). Examples of the carbide include titanium carbide, manganese carbide, and tungsten carbide. Examples of the metal oxide include alumina and tin oxide.
　　　（空隙率）
　第二繊維集合体１１１の空隙率は、例えば、２５％以上９０％以下が挙げられる。第二繊維集合体１１１の空隙率は、圧縮状態の第二繊維集合体１１１の空隙率である。空隙率が２５％以上の第二繊維集合体１１１は、電解液の流通性に優れる。空隙率が９０％以下の第二繊維集合体１１１は、導電性に優れる。第二繊維集合体１１１の空隙率は、更に６０％以上８０％以下が挙げられ、特に７０％以上８０％以下が挙げられる。第二繊維集合体１１１の空隙率の求め方は、第一繊維集合体１７１の空隙率Ｐ１の求め方と同様である。 (Porosity)
The porosity of the second fiber assembly 111 is, for example, 25% or more and 90% or less. The porosity of the second fiber assembly 111 is the porosity of the second fiber assembly 111 in the compressed state. The second fiber aggregate 111 having a porosity of 25% or more is excellent in the flowability of the electrolytic solution. The second fiber assembly 111 having a porosity of 90% or less is excellent in conductivity. The porosity of the second fiber assembly 111 is further 60% or more and 80% or less, and particularly 70% or more and 80% or less. The method of obtaining the porosity of the second fiber assembly 111 is the same as the method of obtaining the porosity P1 of the first fiber assembly 171.
　　　（目付量）
　第二繊維集合体１１１の目付量は、２０ｇ／ｍ２以上６００ｇ／ｍ２以下が挙げられる。目付量が２０ｇ／ｍ２以上の第二繊維集合体１１１は、第二繊維１１１ａ同士の接点を多くし易いため、導電性を高め易い。目付量が６００ｇ／ｍ２以下の第二繊維集合体１１１は、空隙を確保し易いため、電解液の流通性に優れる。第二繊維集合体１１１の目付量は、更に５０ｇ／ｍ２以上５５０ｇ／ｍ２以下が挙げられ、特に１００ｇ／ｍ２以上５００ｇ／ｍ２以下が挙げられる。 (Metsuke amount)
The basis weight of the second fiber assembly 111 is 20 g / m 2 or more and 600 g / m 2 or less. Since the second fiber aggregate 111 having a basis weight of 20 g / m 2 or more tends to have many contacts between the second fibers 111a, it is easy to increase the conductivity. The second fiber aggregate 111 having a basis weight of 600 g / m 2 or less is excellent in the flowability of the electrolytic solution because it is easy to secure voids. The basis weight of the second fiber assembly 111 is further 50 g / m 2 or more and 550 g / m 2 or less, and particularly 100 g / m 2 or more and 500 g / m 2 or less.
　　　（厚さ）
　第二繊維集合体１１１の厚さは、例えば、２００μｍ以上１０００μｍ以下が挙げられる。第二繊維集合体１１１の厚さは、圧縮状態の第二繊維集合体１１１の厚さである。厚さが２００μｍ以上の第二繊維集合体１１１は、電池反応を行う反応場の体積を大きくし易い。厚さが１０００μｍ以下の第二繊維集合体１１１は、薄型のＲＦ電池システム１を構築できる。第二繊維集合体１１１の厚さは、更に３００μｍ以上８００μｍ以下が挙げられ、特に４００μｍ以上７００μｍ以下が挙げられる。第二繊維集合体１１１の厚さは、後述するセルフレーム１６の凹部１６０の深さに相当する。第二繊維集合体１１１の厚さは、５箇所以上の凹部１６０の深さの平均値とする。第二繊維集合体１１１の厚さの測定箇所の一例は、図５を参照して説明した第一交点Ｃ１から第五交点Ｃ５と同様とすることができる。 (thickness)
The thickness of the second fiber assembly 111 is, for example, 200 μm or more and 1000 μm or less. The thickness of the second fiber assembly 111 is the thickness of the second fiber assembly 111 in the compressed state. The second fiber aggregate 111 having a thickness of 200 μm or more tends to increase the volume of the reaction field where the battery reaction is carried out. The second fiber assembly 111 having a thickness of 1000 μm or less can construct a thin RF battery system 1. Further, the thickness of the second fiber assembly 111 is 300 μm or more and 800 μm or less, and particularly 400 μm or more and 700 μm or less. The thickness of the second fiber assembly 111 corresponds to the depth of the recess 160 of the cell frame 16 described later. The thickness of the second fiber assembly 111 is the average value of the depths of the recesses 160 at five or more locations. An example of the measurement point of the thickness of the second fiber assembly 111 can be the same as the first intersection C1 to the fifth intersection C5 described with reference to FIG.
　　　（密度）
　第二繊維集合体１１１の密度は、例えば、０．１ｇ／ｃｍ３以上１．２ｇ／ｃｍ３以下が挙げられる。密度が０．１ｇ／ｃｍ３以上の第二繊維集合体１１１は、第二繊維１１１ａ同士の接点を多くし易いため、導電性を高め易い。密度が１．２ｇ／ｃｍ３以下の第二繊維集合体１１１は、電解液の流通性に優れる。第二繊維集合体１１１の密度は、更に０．１ｇ／ｃｍ３以上１．０ｇ／ｃｍ３以下、０．２ｇ／ｃｍ３以上０．９５ｇ／ｃｍ３以下が挙げられ、特に０．３ｇ／ｃｍ３以上０．９ｇ／ｃｍ３以下が挙げられる。第二繊維集合体１１１の密度は、目付量を厚さで除することで求められる。 (density)
The density of the second fiber assembly 111 is, for example, 0.1 g / cm 3 or more and 1.2 g / cm 3 or less. Since the second fiber assembly 111 having a density of 0.1 g / cm 3 or more tends to have many contacts between the second fibers 111a, it is easy to increase the conductivity. The second fiber assembly 111 having a density of 1.2 g / cm 3 or less is excellent in the flowability of the electrolytic solution. The density of the second fiber aggregate 111 further includes 0.1 g / cm 3 or more and 1.0 g / cm 3 or less, 0.2 g / cm 3 or more and 0.95 g / cm 3 or less, and particularly 0.3 g / cm. 3 or more and 0.9 g / cm 3 or less can be mentioned. The density of the second fiber assembly 111 is obtained by dividing the basis weight by the thickness.
　　［隔膜］
　隔膜１１は、正極電極１４と負極電極１５の間に配置されている。隔膜１１は、正極セルと負極セルとを区画する。隔膜１１は、水素イオンを透過させる。隔膜１１の種類は、例えば、イオン交換膜が挙げられる。隔膜１１は、公知の隔膜を利用できる。隔膜１１の平面形状の一例は、矩形状である。平面形状とは、隔膜１１の第一面又は第二面を平面視したときの第一面又は第二面の輪郭形状である。第一面は、正極電極１４に向かい合う面である。第二面は、負極電極１５に向かい合う面である。 [diaphragm]
The diaphragm 11 is arranged between the positive electrode 14 and the negative electrode 15. The diaphragm 11 partitions the positive electrode cell and the negative electrode cell. The diaphragm 11 allows hydrogen ions to permeate. Examples of the type of diaphragm 11 include an ion exchange membrane. As the diaphragm 11, a known diaphragm can be used. An example of the planar shape of the diaphragm 11 is a rectangular shape. The planar shape is the contour shape of the first surface or the second surface when the first surface or the second surface of the diaphragm 11 is viewed in a plan view. The first surface is a surface facing the positive electrode electrode 14. The second surface is a surface facing the negative electrode electrode 15.
　　　（厚さ）
　隔膜１１の厚さは、例えば、６０μｍ以下が挙げられる。厚さが６０μｍ以下の隔膜１１は、セル抵抗率を低減し易い。このような隔膜１１は、水素イオンを透過させ易いため、電気抵抗を低減させ易いからである。厚さが６０μｍ以下の隔膜１１であっても、第一の層１７によって、電極１００と隔膜１１との接触に伴う隔膜１１の損傷が抑制される。隔膜１１の厚さは、更に４０μｍ以下が挙げられ、特に３０μｍ以下が挙げられる。 (thickness)
The thickness of the diaphragm 11 is, for example, 60 μm or less. The diaphragm 11 having a thickness of 60 μm or less can easily reduce the cell resistivity. This is because such a diaphragm 11 easily allows hydrogen ions to permeate, so that it is easy to reduce the electrical resistance. Even if the diaphragm 11 has a thickness of 60 μm or less, the first layer 17 suppresses damage to the diaphragm 11 due to contact between the electrode 100 and the diaphragm 11. The thickness of the diaphragm 11 is further 40 μm or less, and particularly 30 μm or less.
　隔膜１１の厚さの下限は、例えば、５μｍが挙げられる。厚さが５μｍ以上の隔膜１１は損傷し難い。隔膜１１の厚さは、更に８μｍ以上が挙げられ、特に１０μｍ以上が挙げられる。 The lower limit of the thickness of the diaphragm 11 is, for example, 5 μm. The diaphragm 11 having a thickness of 5 μm or more is not easily damaged. The thickness of the diaphragm 11 is further 8 μm or more, and particularly 10 μm or more.
　即ち、隔膜１１の厚さは、５μｍ以上６０μｍ以下、更に８μｍ以上４０μｍ以下、特に１０μｍ以上３０μｍ以下が挙げられる。 That is, the thickness of the diaphragm 11 is 5 μm or more and 60 μm or less, further 8 μm or more and 40 μm or less, and particularly 10 μm or more and 30 μm or less.
　隔膜１１の厚さは、５箇所以上の厚さの平均値とする。隔膜１１の厚さの測定箇所の一例は、図５を参照して説明した第一交点Ｃ１から第五交点Ｃ５と同様とすることができる。 The thickness of the diaphragm 11 is the average value of the thicknesses of 5 or more places. An example of the measurement point of the thickness of the diaphragm 11 can be the same as the first intersection C1 to the fifth intersection C5 described with reference to FIG.
　電池セル１０は、図２に示すように、２枚のセルフレーム１６の間に設けられる。 As shown in FIG. 2, the battery cell 10 is provided between the two cell frames 16.
　　［セルフレーム］
　セルフレーム１６は、双極板１６１と枠体１６２とを備える。セルフレーム１６は、正極電極１４又は負極電極１５を配置する凹部１６０を備える。凹部１６０は、双極板１６１の表面と枠体１６２の内周面とで形成される。隣接するセルフレーム１６の双極板１６１の間に一つの電池セル１０が形成される。一つの双極板１６１を挟んで表裏に、隣り合う電池セル１０の正極セルと負極セルとが形成される。双極板１６１と枠体１６２とは、公知の構成とすることができる。 [Cell frame]
The cell frame 16 includes a bipolar plate 161 and a frame body 162. The cell frame 16 includes a recess 160 in which the positive electrode 14 or the negative electrode 15 is arranged. The recess 160 is formed by the surface of the bipolar plate 161 and the inner peripheral surface of the frame body 162. One battery cell 10 is formed between the bipolar plates 161 of the adjacent cell frames 16. A positive electrode cell and a negative electrode cell of adjacent battery cells 10 are formed on the front and back sides of one bipolar plate 161. The bipolar plate 161 and the frame body 162 may have known configurations.
　枠体１６２は、双極板１６１の外周縁部を囲む。双極板１６１の表面のうち、外周縁よりも内側の領域は、枠体１６２から露出される。枠体１６２は、双極板１６１を支持する。枠体１６２は、内側に電池セル１０となる領域を形成する。枠体１６２の形状は、矩形枠状である。即ち、凹部１６０の開口形状は、矩形状である。枠体１６２は、給液側片と排液側片とを備える。セルフレーム１６を平面視した際、給液側片と排液側片とが互いに向かい合う方向を縦方向、縦方向に直交する方向を横方向とする。図２では、給液側片が上記縦方向下側、排液側片が上記縦方向上側に位置している。給液側片は、電池セル１０の内部に電解液を供給する給液マニホールド１６３、１６４及び給液スリット１６３ｓ、１６４ｓを有する。排液側片は、電池セル１０の外部に電解液を排出する排液マニホールド１６５、１６６、及び排液スリット１６５ｓ、１６６ｓを有する。電解液が流れる方向は、枠体１６２の上記縦方向下側から上記縦方向上側に向かう方向である。 The frame body 162 surrounds the outer peripheral edge portion of the bipolar plate 161. The region inside the outer peripheral edge of the surface of the bipolar plate 161 is exposed from the frame body 162. The frame body 162 supports the bipolar plate 161. The frame body 162 forms an area to be the battery cell 10 inside. The shape of the frame body 162 is a rectangular frame shape. That is, the opening shape of the recess 160 is rectangular. The frame body 162 includes a liquid supply side piece and a liquid drainage side piece. When the cell frame 16 is viewed in a plan view, the direction in which the liquid supply side piece and the liquid drainage side piece face each other is the vertical direction, and the direction orthogonal to the vertical direction is the horizontal direction. In FIG. 2, the liquid supply side piece is located on the lower side in the vertical direction, and the liquid drain side piece is located on the upper side in the vertical direction. The liquid supply side piece has a liquid supply manifolds 163 and 164 and liquid supply slits 163s and 164s that supply the electrolytic solution to the inside of the battery cell 10. The drainage side piece has a drainage manifold 165, 166 and drainage slits 165s, 166s for draining the electrolytic solution to the outside of the battery cell 10. The direction in which the electrolytic solution flows is from the lower side in the vertical direction to the upper side in the vertical direction of the frame body 162.
　給液側片の内縁には、給液整流部が形成されていてもよい。給液整流部は、給液スリット１６３ｓ、１６４ｓから供給された電解液を給液側片の内縁沿いに拡散する。排液側片の内縁には、排液整流部が形成されていてもよい。排液整流部は、正極電極１４又は負極電極１５を流通した電解液を排液側片の内縁の全域から集約して排液スリット１６５ｓ、１６６ｓに流通させる。給液整流部と排液整流部の図示は省略する。 A liquid supply rectifying unit may be formed on the inner edge of the liquid supply side piece. The liquid supply rectifying unit diffuses the electrolytic solution supplied from the liquid supply slits 163s and 164s along the inner edge of the liquid supply side piece. A drainage rectifying portion may be formed on the inner edge of the drainage side piece. The effluent rectifying unit collects the electrolytic solution flowing through the positive electrode 14 or the negative electrode 15 from the entire inner edge of the effluent side piece and circulates it through the effluent slits 165s and 166s. The illustration of the liquid supply rectifying unit and the drainage rectifying unit is omitted.
　セルフレーム１６における各極電解液の流れは、次の通りである。正極電解液は、給液マニホールド１６３から枠体１６２の第一面側の給液側片に形成される給液スリット１６３ｓを流通して正極電極１４に供給される。この正極電解液は、図２の上図の矢印に示すように、正極電極１４の下側から上側へ流通し、排液側片に形成される排液スリット１６５ｓを流通して排液マニホールド１６５に排出される。負極電解液の供給及び排出は、枠体１６２の第二面側で行われる点を除き、正極電解液と同様である。枠体１６２の第一面と第二面とは、枠体１６２の厚さ方向に向かい合う面である。 The flow of each electrode electrolyte in the cell frame 16 is as follows. The positive electrode electrolytic solution flows from the liquid supply manifold 163 through the liquid supply slit 163s formed in the liquid supply side piece on the first surface side of the frame body 162 and is supplied to the positive electrode electrode 14. As shown by the arrow in the upper part of FIG. 2, the positive electrode electrolytic solution flows from the lower side to the upper side of the positive electrode electrode 14 and flows through the drainage slit 165s formed in the drainage side piece to drain the drainage manifold 165. Is discharged to. The supply and discharge of the negative electrode electrolytic solution are the same as those of the positive electrode electrolytic solution except that the negative electrode electrolytic solution is supplied and discharged on the second surface side of the frame body 162. The first surface and the second surface of the frame body 162 are surfaces facing each other in the thickness direction of the frame body 162.
　各枠体１６２間には、環状のシール溝にＯリングや平パッキンなどの環状のシール部材１６７が配置されている。このシール部材１６７は、電池セル１０からの電解液の漏洩を抑制する。 Between each frame 162, an annular seal member 167 such as an O-ring or flat packing is arranged in an annular seal groove. The seal member 167 suppresses leakage of the electrolytic solution from the battery cell 10.
　　［セルスタック］
　電池セル１０は、通常、図１と図２の下図とに示すように、セルスタック２００と呼ばれる構造体の内部に設けられる。セルスタック２００は、サブスタック２００ｓと、２枚のエンドプレート２２０と、締付機構２３０とを備える。セルスタック２００は、例えば図２の下図に示すように、複数のサブスタック２００ｓを備える。各サブスタック２００ｓは、積層体と、２枚の給排板２１０とを備える。図１と図２の上図とに示す積層体は、セルフレーム１６、正極電極１４、第一の層１７、隔膜１１、及び負極電極１５を、この順番で複数積層して構成されている。給排板２１０は、図２の下図に示すように、積層体の両端に配置される。２枚のエンドプレート２２０は、複数のサブスタック２００ｓを両端のサブスタック２００ｓの外側から挟み込む。締付機構２３０は、両エンドプレート２２０を締め付ける。 [Cell stack]
The battery cell 10 is usually provided inside a structure called a cell stack 200, as shown in FIGS. 1 and 2 below. The cell stack 200 includes a sub-stack 200s, two end plates 220, and a tightening mechanism 230. The cell stack 200 includes a plurality of sub-stacks 200s, for example, as shown in the lower figure of FIG. Each sub-stack 200s includes a laminated body and two supply / discharge plates 210. The laminate shown in FIGS. 1 and 2 is composed of a plurality of cell frames 16, positive electrode 14, first layer 17, diaphragm 11, and negative electrode 15 in this order. As shown in the lower figure of FIG. 2, the supply / discharge plate 210 is arranged at both ends of the laminated body. The two end plates 220 sandwich the plurality of sub-stacks 200s from the outside of the sub-stacks 200s at both ends. The tightening mechanism 230 tightens both end plates 220.
　サブスタック２００ｓ及びセルスタック２００に備わるセルフレーム１６には、中間セルフレームと端部セルフレームとがある。中間セルフレームは、上記積層体の隣り合う電池セル１０の間に配置される。端部セルフレームは、上記積層体の両端に配置される。
中間セルフレームは、双極板１６１の第一面に第一の電池セル１０の正極電極１４が接する。中間セルフレームは、双極板１６１の第二面に第二の電池セル１０の負極電極１５が接する。端部セルフレームは、双極板１６１の第一面に電池セル１０の正極電極１４及び負極電極１５のいずれかの一方の電極が接する。端部セルフレームは、双極板１６１の第二面には電極が存在しない。双極板１６１の第一面と第二面とは、双極板１６１の厚さ方向に向かい合う面である。セルフレーム１６の構成は、中間セルフレーム及び端部セルフレームのいずれにおいても同様である。 The cell frame 16 provided in the sub-stack 200s and the cell stack 200 includes an intermediate cell frame and an end cell frame. The intermediate cell frame is arranged between the adjacent battery cells 10 of the laminated body. The end cell frames are arranged at both ends of the laminate.
In the intermediate cell frame, the positive electrode 14 of the first battery cell 10 is in contact with the first surface of the bipolar plate 161. In the intermediate cell frame, the negative electrode 15 of the second battery cell 10 is in contact with the second surface of the bipolar plate 161. In the end cell frame, one of the positive electrode 14 and the negative electrode 15 of the battery cell 10 is in contact with the first surface of the bipolar plate 161. The end cell frame has no electrodes on the second surface of the bipolar plate 161. The first surface and the second surface of the bipolar plate 161 are surfaces facing each other in the thickness direction of the bipolar plate 161. The configuration of the cell frame 16 is the same for both the intermediate cell frame and the end cell frame.
　　［電解液］
　正極電解液及び負極電解液は、上述したように、正極用循環機構１０Ｐ及び負極用循環機構１０Ｎによって正極電極１４及び負極電極１５に循環される。この循環により、正極電解液及び負極電解液に含まれる活物質であるイオンの価数変化反応に伴って充放電が行われる。 [Electrolytic solution]
As described above, the positive electrode electrolytic solution and the negative electrode electrolytic solution are circulated to the positive electrode electrode 14 and the negative electrode electrode 15 by the positive electrode circulation mechanism 10P and the negative electrode circulation mechanism 10N. By this circulation, charging and discharging are performed according to the valence change reaction of ions which are active materials contained in the positive electrode electrolytic solution and the negative electrode electrolytic solution.
　正極電解液の活物質は、マンガンイオン、バナジウムイオン、鉄イオン、ポリ酸、キノン誘導体、及びアミンからなる群より選択される１種以上を含有することが挙げられる。負極電解液の活物質は、チタンイオン、バナジウムイオン、クロムイオン、ポリ酸、キノン誘導体、及びアミンからなる群より選択される１種以上を含有することが挙げられる。図１は、正極電解液にマンガン（Ｍｎ）イオンを含み、負極電解液にチタン（Ｔｉ）イオンを含む形態を例示している。 The active material of the positive electrode electrolytic solution may contain one or more selected from the group consisting of manganese ion, vanadium ion, iron ion, polyacid, quinone derivative, and amine. The active material of the negative electrode electrolytic solution may contain one or more selected from the group consisting of titanium ion, vanadium ion, chromium ion, polyacid, quinone derivative, and amine. FIG. 1 illustrates a form in which the positive electrode electrolytic solution contains manganese (Mn) ions and the negative electrode electrolytic solution contains titanium (Ti) ions.
　正極活物質の濃度、及び負極活物質の濃度は適宜選択できる。例えば、正極活物質の濃度、及び負極活物質の濃度の少なくとも一方は、０．３ｍｏｌ／Ｌ以上５ｍｏｌ／Ｌ以下が挙げられる。上記濃度が０．３ｍｏｌ／Ｌ以上であれば、大容量の蓄電池として良好に使用できるエネルギー密度を有することができる。このエネルギー密度は、例えば、１０ｋＷｈ／ｍ３程度が挙げられる。上記濃度が高いほどエネルギー密度が高められる。上記濃度は、更に０．５ｍｏｌ／Ｌ以上、１．０ｍｏｌ／Ｌ以上が挙げられ、特に１．２ｍｏｌ／Ｌ以上、１．５ｍｏｌ／Ｌ以上が挙げられる。上記濃度が５ｍｏｌ／Ｌ以下であれば、溶媒に対する溶解度を高め易い。上記濃度は、更に２ｍｏｌ／Ｌ以下が利用し易い。この濃度を満たす電解液は、製造性に優れる。 The concentration of the positive electrode active material and the concentration of the negative electrode active material can be appropriately selected. For example, at least one of the concentration of the positive electrode active material and the concentration of the negative electrode active material is 0.3 mol / L or more and 5 mol / L or less. When the above concentration is 0.3 mol / L or more, it is possible to have an energy density that can be satisfactorily used as a large-capacity storage battery. The energy density is, for example, about 10 kWh / m 3 . The higher the concentration, the higher the energy density. Further, the above-mentioned concentration is 0.5 mol / L or more and 1.0 mol / L or more, and particularly 1.2 mol / L or more and 1.5 mol / L or more. When the above concentration is 5 mol / L or less, the solubility in a solvent can be easily increased. It is easy to use the above concentration of 2 mol / L or less. An electrolytic solution satisfying this concentration is excellent in manufacturability.
　電解液の溶媒は、硫酸、リン酸、硝酸、及び塩酸からなる群より選択される１種以上の酸又は酸塩を含む水溶液などが挙げられる。 Examples of the solvent of the electrolytic solution include an aqueous solution containing one or more acids or acid salts selected from the group consisting of sulfuric acid, phosphoric acid, nitric acid, and hydrochloric acid.
　　［作用効果］
　本形態のＲＦ電池システム１は、電流効率の向上及び反応抵抗率の低下を両立し易い。第一の層１７によって、正極電極１４及び負極電極１５の少なくとも一方と隔膜１１との接触に伴う隔膜１１の損傷が抑制される。その上、第一の層１７を構成する複数の第一繊維１７１ａと隔膜１１との接触に伴う隔膜１１の損傷が抑制される。隔膜１１の損傷が抑制されることで、正極電解液と負極電解液とが隔膜１１の損傷部分を介して短絡することが抑制される。よって、本開示のＲＦ電池システム１は、電流効率を向上し易い。第一の層１７は、電解液を拡散させ易い。よって、本開示のＲＦ電池システム１は、反応抵抗率を低下させ易い。 [Action effect]
The RF battery system 1 of this embodiment can easily achieve both improvement in current efficiency and reduction in reaction resistivity. The first layer 17 suppresses damage to the diaphragm 11 due to contact between at least one of the positive electrode 14 and the negative electrode 15 and the diaphragm 11. In addition, damage to the diaphragm 11 due to contact between the plurality of first fibers 171a constituting the first layer 17 and the diaphragm 11 is suppressed. By suppressing the damage to the diaphragm 11, it is possible to prevent the positive electrode electrolytic solution and the negative electrode electrolytic solution from being short-circuited through the damaged portion of the diaphragm 11. Therefore, the RF battery system 1 of the present disclosure tends to improve the current efficiency. The first layer 17 easily diffuses the electrolytic solution. Therefore, the RF battery system 1 of the present disclosure tends to reduce the reaction resistivity.
　《試験例》
　試験例では、第一の層の有無、及び第一の層の構成の違いによる電池特性の違いを調べた。 << Test example >>
In the test example, the difference in battery characteristics due to the presence or absence of the first layer and the difference in the configuration of the first layer was investigated.
　〔試料Ｎｏ．１〕
　試料Ｎｏ．１では、電池セルとして単セル電池を用意した。単セル電池は、第一のセルフレーム、正極電極、隔膜、負極電極、第二のセルフレームを順に積層することで構成した。試料Ｎｏ．１の電池セルは、正極電極と隔膜との間及び負極電極と隔膜との間のいずれの間にも第一の層が配置されていない。表２に示す第一の層の欄の「－」は、第一の層が配置されていないことを意味する。 [Sample No. 1]
Sample No. In No. 1, a single cell battery was prepared as the battery cell. The single cell battery was constructed by stacking the first cell frame, the positive electrode, the diaphragm, the negative electrode, and the second cell frame in this order. Sample No. In battery cell 1, the first layer is not arranged between the positive electrode and the diaphragm and between the negative electrode and the diaphragm. “-” In the column of the first layer shown in Table 2 means that the first layer is not arranged.
　隔膜には、陽イオン交換膜を用いた。隔膜の厚さは、１５μｍとした。隔膜の厚さは、上述した５箇所以上の厚さを平均して求めた。
　正極電極には、炭素繊維からなる不織布を用いた。正極電極の諸元は、表１に示す通りである。正極電極を構成する炭素繊維の平均直径及び平均ヤング率の測定方法と、正極電極の厚さ、目付量、密度、及び空隙率の測定方法とは、試料Ｎｏ．２などの第一の層の測定方法と併せて後述する。
　負極電極には、正極電極と同じ不織布を用いた。
　正極電極及び負極電極の各々の反応面積は、９ｃｍ２程度とした。 A cation exchange membrane was used as the diaphragm. The thickness of the diaphragm was 15 μm. The thickness of the diaphragm was determined by averaging the thicknesses of the above-mentioned five or more locations.
A non-woven fabric made of carbon fiber was used for the positive electrode. The specifications of the positive electrode are as shown in Table 1. The method for measuring the average diameter and the average Young's modulus of the carbon fibers constituting the positive electrode and the method for measuring the thickness, the amount of the grain, the density, and the void ratio of the positive electrode are described in Sample No. It will be described later together with the measurement method of the first layer such as 2.
The same non-woven fabric as the positive electrode was used for the negative electrode.
The reaction area of each of the positive electrode and the negative electrode was about 9 cm 2 .
　〔試料Ｎｏ．２から試料Ｎｏ．７〕
　試料Ｎｏ．２から試料Ｎｏ．７では、正極電極と隔膜との間に第一の層が配置されている点を除き、試料Ｎｏ．１の電池セルと同様の単セル電池を用意した。試料Ｎｏ．２から試料Ｎｏ．７のＲＦ電池システムは、負極電極と隔膜との間には第一の層が配置されていない。試料Ｎｏ．２から試料Ｎｏ．６の第一の層は、ＰＰＳ（ポリフェニレンスルフィド）からなる複数の第一繊維を有する第一繊維集合体である。試料Ｎｏ．７の第一の層は、ＰＥ（ポリエチレン）からなる複数の第一繊維を有する第一繊維集合体である。試料Ｎｏ．２から試料Ｎｏ．７の第一の層の諸元は、表２に示す通りである。 [Sample No. From sample No. 2 7]
Sample No. From sample No. 2 In No. 7, the sample No. 7 was prepared except that the first layer was arranged between the positive electrode and the diaphragm. A single cell battery similar to the battery cell of No. 1 was prepared. Sample No. From sample No. 2 In the RF battery system of No. 7, the first layer is not arranged between the negative electrode and the diaphragm. Sample No. From sample No. 2 The first layer of 6 is a first fiber assembly having a plurality of first fibers composed of PPS (polyphenylene sulfide). Sample No. The first layer of No. 7 is a first fiber aggregate having a plurality of first fibers made of PE (polyethylene). Sample No. From sample No. 2 The specifications of the first layer of 7 are as shown in Table 2.
　〔測定方法〕
　表１に示す正極電極を構成する炭素繊維の平均直径及び平均ヤング率と、正極電極の厚さ、目付量、密度、及び空隙率と、表２に示す第一の層を構成する複数の第一繊維の平均直径及び平均ヤング率と、第一の層の厚さ、目付量、密度、及び空隙率とは、次のようにして求めた。
　厚さとは、圧縮状態の正極電極及び第一の層の厚さである。
　空隙率とは、圧縮状態の正極電極及び第一の層の空隙率である。 〔Measuring method〕
The average diameter and average Young's modulus of the carbon fibers constituting the positive electrode shown in Table 1, the thickness, the amount of grain, the density, and the void ratio of the positive electrode, and the plurality of orders constituting the first layer shown in Table 2. The average diameter and the average Young's modulus of one fiber and the thickness, the amount of the grain, the density, and the void ratio of the first layer were determined as follows.
The thickness is the thickness of the compressed positive electrode and the first layer.
The porosity is the porosity of the compressed positive electrode and the first layer.
　繊維の平均直径は、５本の繊維の直径を平均して求めた。各繊維の直径は、各繊維の断面の面積と同じ面積を有する円の直径である。
　繊維の平均ヤング率は、５本の繊維のヤング率を平均して求めた。
　厚さは、上述した５箇所の厚さを平均して求めた。各箇所の厚さは、正極電極及び第一の層に０．２ＭＰａの圧力を作用させた状態で測定した厚さである。
　目付量は、単位面積当たりの重量を測定して求めた。
　密度は、目付量を厚さで除して求めた。
　第一の層の空隙率は、上述した第一繊維集合体１７１の空隙率Ｐ１の求め方と同様にして求めた。正極電極の空隙率は、第一の層の空隙率の求め方と同様の求め方によって求めた。 The average diameter of the fibers was determined by averaging the diameters of the five fibers. The diameter of each fiber is the diameter of a circle having the same area as the cross-sectional area of each fiber.
The average Young's modulus of the fibers was determined by averaging the Young's modulus of the five fibers.
The thickness was determined by averaging the thicknesses of the above-mentioned five locations. The thickness of each portion is a thickness measured in a state where a pressure of 0.2 MPa is applied to the positive electrode and the first layer.
The basis weight was determined by measuring the weight per unit area.
The density was determined by dividing the basis weight by the thickness.
The porosity of the first layer was determined in the same manner as the method for determining the porosity P1 of the first fiber aggregate 171 described above. The porosity of the positive electrode was determined by the same method as the method for determining the porosity of the first layer.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　〔電池特性の測定〕
　各試料の電池セルに電流密度が２５６ｍＡ／ｃｍ２の定電流で充放電を行った。この試験では、５サイクルの充放電を行った。この試験では、予め設定した所定の切替電圧に達したら、充電から放電に切り替え、予め設定した所定の切替電圧に達したら、放電から充電に切り替えた。充電から放電への切替電圧は１．６２Ｖとした。放電から充電への切替電圧は１．００Ｖとした。 [Measurement of battery characteristics]
The battery cells of each sample were charged and discharged with a constant current having a current density of 256 mA / cm 2 . In this test, 5 cycles of charging and discharging were performed. In this test, when a preset predetermined switching voltage was reached, charging was switched to discharging, and when a preset predetermined switching voltage was reached, discharging was switched to charging. The switching voltage from charging to discharging was 1.62V. The switching voltage from discharge to charge was 1.00 V.
　充放電後、各試料の電流効率（％）、セル抵抗率（Ω・ｃｍ２）、導電抵抗率（Ω・ｃｍ２）、及び反応抵抗率（Ω・ｃｍ２）を求めた。
　電流効率は、サイクルごとに（放電時間の合計／充電時間の合計）×１００により算出したものを平均した値とした。
　セル抵抗率は、｛（充電時の平均電圧と放電時の平均電圧の差）／（平均電流／２）｝×電極の有効面積、により算出したものとした。充電時の平均電圧及び放電時の平均電圧は、複数サイクルのうち、任意の１サイクルにおける平均電圧とした。
　導電抵抗率は、交流インピーダンス法において、測定周波数が１ｋＨｚのときのインピーダンスとした。
　反応抵抗率は、セル抵抗率から導電抵抗率を引いた値とした。
　それらの結果を表３に示す。 After charging and discharging, the current efficiency (%), cell resistivity (Ω · cm 2 ), conductivity resistivity (Ω · cm 2 ), and reaction resistivity (Ω · cm 2 ) of each sample were determined.
The current efficiency was calculated by multiplying each cycle (total discharge time / total charge time) × 100 and used as an average value.
The cell resistivity was calculated by {(difference between average voltage during charging and average voltage during discharging) / (average current / 2)} × effective area of the electrode. The average voltage during charging and the average voltage during discharging were defined as the average voltage in any one cycle among the plurality of cycles.
The conductivity resistivity is the impedance when the measurement frequency is 1 kHz in the AC impedance method.
The reaction resistivity was a value obtained by subtracting the conductivity resistivity from the cell resistivity.
The results are shown in Table 3.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表３に示すように、試料Ｎｏ．２から試料Ｎｏ．６の電流効率は、試料Ｎｏ．１よりも高い。このような結果となった理由は、第一の層によって、隔膜の損傷を抑制できたからだと考えられる。試料Ｎｏ．２から試料Ｎｏ．６の反応抵抗率は、試料Ｎｏ．１よりも小さい。このような結果となった理由は、第一の層を備えているにも関わらず、電解液の拡散が阻害され難かったからだと考えられる。その結果、電極が良好に電池反応を行うことができたと考えられる。試料Ｎｏ．７の電流効率は、試料Ｎｏ．２から試料Ｎｏ．６よりも低い。このような結果となった理由は、試料Ｎｏ．７の第一の層の空隙率は２０％以上９９％以下を満たすものの、平均直径が５０μｍ超である第一繊維の剛性が高くなることで、第一繊維が隔膜を損傷させたからだと考えられる。 As shown in Table 3, sample No. From sample No. 2 The current efficiency of No. 6 is the sample No. Higher than 1. The reason for this result is considered to be that the first layer was able to suppress the damage to the diaphragm. Sample No. From sample No. 2 The reaction resistivity of No. 6 is the sample No. Less than 1. It is considered that the reason for such a result is that the diffusion of the electrolytic solution was hardly inhibited even though the first layer was provided. As a result, it is considered that the electrodes were able to carry out the battery reaction satisfactorily. Sample No. The current efficiency of No. 7 is the sample No. From sample No. 2 Lower than 6. The reason for this result is the sample No. Although the porosity of the first layer of No. 7 satisfies 20% or more and 99% or less, it is considered that the first fiber damaged the diaphragm due to the increased rigidity of the first fiber having an average diameter of more than 50 μm. Be done.
　その他、正極電極と隔膜との間に以下の第一の層を配置させる場合、以下の結果になると考えられる。
　空隙率が２０％以上９９％以下を満たすものの、第一繊維の平均直径が２μｍ未満の第一の層は、目詰まりが生じることで、電解液の流通性が悪化する。
　第一繊維の平均直径が２μｍ以上５０μｍ以下を満たすものの、空隙率が２０％未満の第一の層は、目詰まりが生じることで、電解液の流通性が悪化する。
　第一繊維の平均直径が２μｍ以上５０μｍ以下を満たすものの、空隙率が９９％超の第一の層は、電池セル内で、第一の層の形状を保持できない。 In addition, when the following first layer is arranged between the positive electrode and the diaphragm, the following results are considered.
Although the porosity satisfies 20% or more and 99% or less, the first layer having an average diameter of less than 2 μm of the first fiber is clogged, so that the flowability of the electrolytic solution deteriorates.
Although the average diameter of the first fiber satisfies 2 μm or more and 50 μm or less, the first layer having a porosity of less than 20% is clogged and the flowability of the electrolytic solution deteriorates.
Although the average diameter of the first fiber satisfies 2 μm or more and 50 μm or less, the first layer having a porosity of more than 99% cannot retain the shape of the first layer in the battery cell.
　本発明は、これらの例示に限定されるものではなく、請求の範囲によって示され、請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 The present invention is not limited to these examples, but is indicated by the claims and is intended to include all modifications within the meaning and scope equivalent to the claims.
　１　ＲＦ電池システム
　１０　電池セル
　１１　隔膜、１４　正極電極、１５　負極電極
　１６　セルフレーム、１６０　凹部、１６１　双極板、１６２　枠体
　１６３、１６４　給液マニホールド、１６３ｓ、１６４ｓ　給液スリット
　１６５、１６６　排液マニホールド、１６５ｓ、１６６ｓ　排液スリット
　１６７　シール部材
　１７　第一の層、１７１　第一繊維集合体、１７１ａ　第一繊維
　Ｗａ　幅、Ｌａ　長さ
　Ｃ１　第一交点、Ｃ２　第二交点、Ｃ３　第三交点
　Ｃ４　第四交点、Ｃ５　第五交点
　Ｖ１　第一仮想線、Ｖ２　第二仮想線
　Ｖ３　第三仮想線、Ｖ４　第四仮想線
　Ｄ１、Ｄ２　対角線
　１０Ｐ　正極用循環機構、１０Ｎ　負極用循環機構
　１８　正極電解液タンク、１９　負極電解液タンク
　２０、２１　供給管、２２、２３　排出管、２４、２５　ポンプ
　１００　電極、１１１　第二繊維集合体、１１１ａ　第二繊維
　２００　セルスタック、２００ｓ　サブスタック
　２１０　給排板、２２０　エンドプレート、２３０　締付機構
　５００　交流／直流変換器
　５１０　発電部、５２０　変電設備、５３０　負荷 1 RF battery system 10 Battery cell 11 diaphragm, 14 positive electrode, 15 negative electrode 16 cell frame, 160 recess, 161 bipolar plate, 162 frame 163, 164 liquid supply manifold, 163s, 164s liquid supply slit 165, 166 drainage manifold , 165s, 166s Drainage slit 167 Sealing member 17 First layer, 171 First fiber assembly, 171a First fiber Wa width, La length C1 First intersection, C2 Second intersection, C3 Third intersection C4 Fourth Intersection, C5 Fifth intersection V1 First virtual line, V2 Second virtual line V3 Third virtual line, V4 Fourth virtual line D1, D2 Diagonal line 10P Positive electrode circulation mechanism, 10N Negative electrode circulation mechanism 18 Positive electrode electrolyte tank, 19 Negative electrode electrolyte tank 20, 21 Supply pipe, 22, 23 Discharge pipe, 24, 25 Pump 100 Electrode, 111 Second fiber assembly, 111a Second fiber 200 cell stack, 200s Substack 210 Supply / discharge plate, 220 end plate, 230 Tightening mechanism 500 AC / DC converter 510 Power generation unit, 520 Substation equipment, 530 Load

Claims (10)

  1. 　正極電極と負極電極と隔膜とを備える電池セルであって、
    　前記正極電極と前記隔膜との間及び前記負極電極と前記隔膜との間の少なくとも一方の間に配置されている第一の層を備え、
    　前記第一の層は、絶縁材料からなる複数の第一繊維を有する第一繊維集合体であり、
    　前記複数の第一繊維の平均直径は、２μｍ以上５０μｍ以下であり、
    　前記第一繊維集合体の空隙率は、２０％以上９９％以下である、
    電池セル。     A battery cell including a positive electrode, a negative electrode, and a diaphragm.
    It comprises a first layer disposed between the positive electrode and the diaphragm and between at least one of the negative electrode and the diaphragm.
    The first layer is a first fiber aggregate having a plurality of first fibers made of an insulating material.
    The average diameter of the plurality of first fibers is 2 μm or more and 50 μm or less.
    The porosity of the first fiber aggregate is 20% or more and 99% or less.
    Battery cell.
  2. 　前記第一繊維集合体の目付量は、５ｇ／ｍ２以上１００ｇ／ｍ２以下である請求項１に記載の電池セル。 The battery cell according to claim 1, wherein the basis weight of the first fiber aggregate is 5 g / m 2 or more and 100 g / m 2 or less.
  3. 　前記第一繊維集合体の厚さは、５μｍ以上３０００μｍ以下である請求項１又は請求項２に記載の電池セル。 The battery cell according to claim 1 or 2, wherein the thickness of the first fiber aggregate is 5 μm or more and 3000 μm or less.
  4. 　前記第一繊維集合体の密度は、０．１ｇ／ｃｍ３以上１．２ｇ／ｃｍ３以下である請求項１から請求項３のいずれか１項に記載の電池セル。 The battery cell according to any one of claims 1 to 3, wherein the density of the first fiber aggregate is 0.1 g / cm 3 or more and 1.2 g / cm 3 or less.
  5. 　前記絶縁材料は、樹脂、又はセラミックスであり、
    　前記樹脂は、ポリフェニレンスルフィド、ポリエチレン、ポリプロピレン、ポリアミド、ポリ塩化ビニル、ポリスチレン、ポリブチレンサクシネート、アクリル、ポリテトラフルオロエチレン、テトラフルオロエチレン・エチレン共重合体、ポリカーボネート、フェノール、又はエポキシであり、
    　前記セラミックスは、シリカ、アルミナ、ジルコニア、又は炭化ケイ素である請求項１から請求項４のいずれか１項に記載の電池セル。     The insulating material is resin or ceramics.
    The resin is polyphenylene sulfide, polyethylene, polypropylene, polyamide, polyvinyl chloride, polystyrene, polybutylene succinate, acrylic, polytetrafluoroethylene, tetrafluoroethylene / ethylene copolymer, polycarbonate, phenol, or epoxy.
    The battery cell according to any one of claims 1 to 4, wherein the ceramic is silica, alumina, zirconia, or silicon carbide.
  6. 　前記複数の第一繊維の平均ヤング率は、２００ＧＰａ以下である請求項１から請求項５のいずれか１項に記載の電池セル。 The battery cell according to any one of claims 1 to 5, wherein the average Young's modulus of the plurality of first fibers is 200 GPa or less.
  7. 　前記隔膜の厚さは、６０μｍ以下である請求項１から請求項６のいずれか１項に記載の電池セル。 The battery cell according to any one of claims 1 to 6, wherein the thickness of the diaphragm is 60 μm or less.
  8. 　前記正極電極及び前記負極電極のうち少なくとも前記第一の層に隣り合う電極は、導電材料からなる複数の第二繊維を有する第二繊維集合体であり、
    　前記第二繊維集合体は、不織布、織布、又はペーパーである請求項１から請求項７のいずれか１項に記載の電池セル。     Of the positive electrode and the negative electrode, the electrode adjacent to at least the first layer is a second fiber aggregate having a plurality of second fibers made of a conductive material.
    The battery cell according to any one of claims 1 to 7, wherein the second fiber aggregate is a non-woven fabric, a woven fabric, or paper.
  9. 　複数の電池セルを備え、
    　前記複数の電池セルの少なくとも一つが請求項１から請求項８のいずれか１項に記載の電池セルである、
    セルスタック。     Equipped with multiple battery cells
    The battery cell according to any one of claims 1 to 8, at least one of the plurality of battery cells.
    Cell stack.
  10. 　請求項１から請求項８のいずれか１項に記載の電池セル、又は請求項９に記載のセルスタックを備える、
    レドックスフロー電池システム。     The battery cell according to any one of claims 1 to 8, or the cell stack according to claim 9.
    Redox flow battery system.
PCT/JP2021/035847 2021-01-12 2021-09-29 Battery cell, cell stack, and redox flow battery system WO2022153615A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2021002853 2021-01-12
JP2021-002853 2021-01-12

Publications (1)

Publication Number Publication Date
WO2022153615A1 true WO2022153615A1 (en) 2022-07-21

Family

ID=82448264

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2021/035847 WO2022153615A1 (en) 2021-01-12 2021-09-29 Battery cell, cell stack, and redox flow battery system

Country Status (1)

Country Link
WO (1) WO2022153615A1 (en)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02148658A (en) * 1988-11-30 1990-06-07 Toyobo Co Ltd Liquid flow type electrolytic cell
JP2015176648A (en) * 2014-03-13 2015-10-05 旭化成イーマテリアルズ株式会社 Electrode layer with resin, electrode composite body with resin, and redox flow secondary battery
WO2016104613A1 (en) * 2014-12-26 2016-06-30 昭和電工株式会社 Electrode for redox flow batteries, and redox flow battery

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02148658A (en) * 1988-11-30 1990-06-07 Toyobo Co Ltd Liquid flow type electrolytic cell
JP2015176648A (en) * 2014-03-13 2015-10-05 旭化成イーマテリアルズ株式会社 Electrode layer with resin, electrode composite body with resin, and redox flow secondary battery
WO2016104613A1 (en) * 2014-12-26 2016-06-30 昭和電工株式会社 Electrode for redox flow batteries, and redox flow battery

Similar Documents

Publication Publication Date Title
KR102272748B1 (en) Bipolar plates, cell frames, cell stacks, and redox flow batteries
JP6819885B2 (en) Bipolar plate, cell frame and cell stack, and redox flow battery
KR102382373B1 (en) Battery cell and redox flow battery
JP6701514B2 (en) Redox flow battery electrode and redox flow battery
AU2016342919B2 (en) Redox flow battery electrode, and redox flow battery
JP2015122229A (en) Electrode, and redox flow cell
JP6970388B2 (en) Redox flow battery electrodes, redox flow battery cells and redox flow batteries
WO2022153615A1 (en) Battery cell, cell stack, and redox flow battery system
WO2019012984A1 (en) Bipolar plate, cell frame, battery cell, cell stack, and redox flow battery
JP6903286B2 (en) Redox flow battery
JP7068613B2 (en) Redox flow battery cell and redox flow battery
WO2018134955A1 (en) Bipolar plate, cell frame, cell stack and redox flow battery
JPWO2020158624A1 (en) Battery cells, cell stacks, and redox flow batteries
TW202036971A (en) Battery cell, cell stack and redox flow battery
JP7486060B2 (en) Cell stack and redox flow battery
WO2023132152A1 (en) Electrode, battery cell, cell stack, and redox-flow battery system
US20230369627A1 (en) Cell stack and redox flow battery
WO2022209113A1 (en) Electrode, battery cell, and redox flow battery
JP2023100373A (en) Electrode, battery cell, cell stack, and redox flow battery system
JP2022077462A (en) Electrode, battery cell, cell stack, and redox flow battery system
TW202046546A (en) Battery cell, cell stack and redox flow battery
JPWO2019234867A1 (en) Bipolar plate, cell frame, cell stack, and redox flow battery

Legal Events

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

Ref document number: 21919506

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 21919506

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: JP