WO2020195862A1 - 複合材及びその製造方法、並びに当該複合材を用いた燃料電池用のセパレータ、セル及びスタック - Google Patents

複合材及びその製造方法、並びに当該複合材を用いた燃料電池用のセパレータ、セル及びスタック Download PDF

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WO2020195862A1
WO2020195862A1 PCT/JP2020/010677 JP2020010677W WO2020195862A1 WO 2020195862 A1 WO2020195862 A1 WO 2020195862A1 JP 2020010677 W JP2020010677 W JP 2020010677W WO 2020195862 A1 WO2020195862 A1 WO 2020195862A1
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composite material
layer
carbon layer
thickness
base material
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PCT/JP2020/010677
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English (en)
French (fr)
Japanese (ja)
Inventor
悠 佐藤
能勢　幸一
村上　信吉
中塚　淳
翔平 河合
俊夫 岩崎
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日鉄ケミカル＆マテリアル株式会社
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Priority to JP2021509016A priority Critical patent/JP7448522B2/ja
Publication of WO2020195862A1 publication Critical patent/WO2020195862A1/ja

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0206—Metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0213—Gas-impermeable carbon-containing materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0215—Glass; Ceramic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0221—Organic resins; Organic polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0223—Composites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0223—Composites
    • H01M8/0228—Composites in the form of layered or coated products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0247—Collectors; Separators, e.g. bipolar separators; Interconnectors characterised by the form
    • 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
    • H01M8/10—Fuel cells with solid electrolytes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a composite material and a method for producing the same, and a separator, a cell and a stack for a fuel cell using the composite material.
  • FIGS. 5 and 6 (a) and 6 (b) examples of the fuel cell and the separator for the fuel cell are shown in FIGS. 5 and 6 (a) and 6 (b).
  • FIG. 5 is an exploded view showing the configuration of the unit cells constituting the fuel cell 17
  • FIG. 6 is a diagram showing the configuration of the fuel cell separator 5 shown in FIG. 6 (a) is a plan view
  • FIG. 6 (b) is a cross-sectional view taken along the line XY of FIG. 6 (a).
  • the polymer electrolyte fuel cell 17 is a stack in which dozens to hundreds of configurations 10 which are unit cells are stacked.
  • a MEA membrane ejector assembly: membrane / electrode assembly
  • a solid polymer electrolyte membrane 6 composed of a solid polymer electrolyte membrane 6, an anode (fuel electrode) 7 and a cathode (oxidizing agent electrode) 8 is provided on two fuel cell separators 5. It is sandwiched through the gasket 9.
  • the fuel gas hydrogen gas
  • oxygen gas oxygen gas
  • the fuel cell separator 5 has a plurality of gas supply / discharge grooves 11 and a gas supply / discharge groove 11 on one side or both sides of a thin plate-like body.
  • the groove 11 has an opening 12 for supplying fuel gas or an oxidation gas, and a fixing hole 13 for arranging MEAs in parallel.
  • the fuel cell separator 5 has a role of separating the fuel gas flowing in the fuel cell and the oxidation gas so as not to be mixed, transfers the electric energy generated by the MEA to the outside, and transfers the heat generated by the MEA to the outside. It plays an important role of dissipating heat to.
  • the characteristics required for the fuel cell separator include the above-mentioned supply of fuel gas, etc., the function as a flow path for discharging the water generated at the cathode and the gas after the reaction, and the usage environment inside the battery (high temperature, It has long-term durability (corrosion resistance) under (corrosiveness, low pH, etc.), has low electrical resistance and excellent conductivity (high conductivity, low contact resistance) to reduce power generation loss, and fuel gas. And the oxide gas may have gas impermeableness for completely separating both sides. In addition, it is also required to have strength and flexibility (flexibility) that does not break even when bolted or vibrated during assembly, assuming molding processability or in-vehicle use.
  • Patent Documents 1 to 3 are advantageous in terms of achieving sufficient corrosion resistance and improving the chemical stability of the layer.
  • the outermost carbon layer is several nm to several tens of ⁇ m, and it cannot be said that sufficient corrosion resistance can be realized in a fuel cell environment. Further, if there are cracks in the metal coat layer under the carbon layer, the insufficient corrosion resistance may become apparent. Further, if a metal coat layer having high corrosion resistance that forms a passivation state is provided, it may be difficult for the passivation film (oxide film) to exhibit sufficient conductivity.
  • a metal (stainless steel) base material is surface-treated with a predetermined mixed aqueous solution of hydrofluoric acid and nitric acid to reduce the contact resistance and the surface thereof. It has been confirmed that a stainless steel plate carbon composite material in which a carbon layer composed of carbon powder and resin powder is laminated relatively thickly on a base material after treatment is excellent in corrosion resistance, conductivity, flexibility and the like. (See Patent Documents 4 and 5).
  • the inventors of the present application considered that in order to improve the adhesion between the base material and the carbon layer, it is necessary to study the base material side instead of the carbon layer. Therefore, as a result of studying the base material side, it was confirmed that the adhesion between the chrome plating layer and the matrix resin in the carbon layer is improved and the corrosion resistance is further improved by providing the chrome plating layer on the base material surface. Was done. Furthermore, it was found that by providing the base material with a chromium-plated layer in this way, the options for the steel material that is the base material of the base material can be expanded.
  • chromium is known to form a dense oxide film (passive film; referred to herein as the "chromium oxide layer") by natural oxidation. ..
  • the inventors of the present application formed a chrome-plated layer on a base material and formed a similar carbon layer on the chrome-plated layer, but could not obtain satisfactory conductivity (contact resistance). It was considered that this was due to the decrease in conductivity of the surface of the chromium plating layer caused by the formation of the chromium oxide layer.
  • the inventors of the present application have investigated measures for improving the decrease in conductivity of the substrate surface due to such a chromium oxide layer.
  • the chromium plating layer may be peeled off by processing such as shot blasting or polishing or surface treatment with an acid aqueous solution. Therefore, normally, such processing / surface treatment is not positively performed on the chrome-plated layer.
  • the thickness of the base material provided with the chrome-plated layer can be reduced while maintaining the chrome-plated layer by performing a short-time surface treatment with an acid aqueous solution. It was confirmed that satisfactory conductivity could be obtained.
  • the gist of the present invention is as follows.
  • the plate-shaped base material has a chromium-plated steel material having a chromium-plated layer on the surface of the steel material, and a chromium oxide layer having a thickness of less than 20 nm formed on the surface thereof.
  • the carbon layer is a composite material containing a carbonaceous material and a matrix resin made of a thermoplastic resin or a thermosetting resin and having a thickness of 0.1 mm to 3.0 mm.
  • the process of preparing chrome-plated steel by chrome-plating the surface of the steel A surface treatment process in which at least one side of the chrome-plated steel is treated with an acid aqueous solution, A method for producing a composite material, which comprises a carbon layer forming step of forming a carbon layer containing a carbonaceous material and a matrix resin made of a thermoplastic resin or a thermosetting resin on at least one surface of the chrome-plated steel material after surface treatment.
  • the present invention it is possible to provide a composite material having excellent conductivity, corrosion resistance, adhesion between a base material and a carbon layer, excellent selectivity of a base material, and good cost.
  • the composite material according to the present invention can be suitably used as a separator, cell and stack for a fuel cell.
  • FIG. 1 is a schematic explanatory view of a composite material manufacturing process.
  • FIG. 2 is a schematic explanatory view of a molding method for producing a carbon layer or a composite material.
  • FIG. 3 is a schematic explanatory view of a method of laminating a carbon layer, an adhesive layer, and a base material in the production of the composite material of the present invention.
  • FIG. 4 is a schematic explanatory view of a method for measuring contact resistance.
  • FIG. 5 is an exploded view showing an example of the configuration of the unit cells constituting the fuel cell.
  • FIG. 6A is a plan view showing an example of a fuel cell separator, and
  • FIG. 6B is a cross-sectional view showing a cross section taken along line XY of FIG. 6A.
  • the composite material of the present embodiment includes a conductive carbon layer on at least one surface of the plate-shaped base material.
  • the plate-shaped base material is composed of a chromium-plated steel material having a chromium-plated layer on the surface of the steel material and a chromium oxide layer having a predetermined thickness formed on the surface thereof.
  • the base material used in this embodiment is plate-shaped and uses a steel material (steel material) as a base material.
  • the steel material can be widely selected from known ones, and for example, stainless steel having good corrosion resistance is preferable. When carbon steel or low carbon steel is used, those having good corrosion resistance are preferable.
  • the stainless steel refers to a steel having a chromium (Cr) content of 10.5% by mass or more, and may be, for example, austenitic, martensitic, ferritic or a two-phase system of austenitic and ferritic.
  • the carbon steel refers to a material whose main component is iron (Fe) and whose total Cr concentration is less than 2% by mass.
  • low carbon steel refers to a material whose main component is iron (Fe) and whose total Cr concentration is 2% by mass or more and less than 10.5% by mass.
  • the size of the plate-shaped base material is appropriately set according to the purpose and application of use. If the thickness of the base metal is too small, the strength may be insufficient. If the thickness of the base material is too large, for example, when the composite material of the present embodiment is used as a separator for a fuel cell, there is a concern that it may affect high integration.
  • the lower limit of the thickness of the base metal is preferably 0.010 mm, more preferably 0.015 mm, and even more preferably 0.020 mm.
  • the upper limit of the thickness of the base metal is preferably 0.20 mm, more preferably 0.18 mm, and even more preferably 0.15 mm.
  • a chrome-plated layer is provided on the surface of the steel material.
  • Chromium plating on the steel material can be performed by a known method.
  • an electroplating method in which cathode electrolysis is performed using an object to be plated (steel material in this embodiment) as a cathode in an aqueous solution containing chromic acid (chromic anhydride) as a main component can be mentioned.
  • electrolytic chromic acid treatment may be performed for the purpose of further improving corrosion resistance.
  • the electrolytic chromic acid treatment is performed, for example, by electrolytic treatment in a non-sulfuric acid aqueous solution containing one or more of chromic acid, chromate and dichromate as a main component.
  • a chrome-plated layer is formed on the surface of the steel material, and a chrome-plated steel material (chrome-plated steel material) can be obtained (preparation step of the chrome-plated steel material).
  • the thickness of the chrome plating layer is too small, the effect of improving corrosion resistance may be insufficient. If the thickness of the chrome-plated layer is too large, the chrome-plated layer may be damaged during the subsequent processing (surface treatment).
  • the lower limit of the thickness of the chrome-plated layer is preferably 0.01 ⁇ m, more preferably 0.02 ⁇ m.
  • the upper limit of the thickness of the chrome-plated layer is preferably 1.0 ⁇ m, more preferably 0.8 ⁇ m.
  • the above thickness can be adjusted by appropriately adjusting the current value, electrolysis time, and the like.
  • the thickness of the chrome-plated layer is measured, for example, by X-ray photoelectron spectroscopy (XPS).
  • XPS X-ray photoelectron spectroscopy
  • the chrome-plated steel material is rapidly spontaneously oxidized by oxygen in the air to form a natural oxide film (chromium oxide layer) of about 20 to 30 nm.
  • a natural oxide film chromium oxide layer
  • Such a relatively thick chromium oxide layer may contribute to a certain degree in terms of corrosion resistance, but on the other hand, it increases contact resistance and significantly lowers the conductivity of the surface.
  • a treatment for reducing the thickness of such a relatively thick chromium oxide layer is required.
  • the steel material in which the chromium oxide layer is formed on the chromium plating layer is subjected to surface treatment using an acid aqueous solution (treatment aqueous solution) (surface treatment step).
  • treatment aqueous solution an acid aqueous solution
  • the treatment method include a method of immersing the steel material in the acid aqueous solution and a method of spraying the acid aqueous solution onto the steel material, which are appropriately selected depending on the treatment range and the like.
  • the acid aqueous solution is not limited as long as it can dissolve the chromium oxide layer.
  • the acid aqueous solution examples include a non-oxidizing acid aqueous solution such as hydrofluoric acid, sulfuric acid and hydrochloric acid, an oxidizing acid aqueous solution such as nitric acid, or a mixed solution containing them.
  • the concentration of the acid solution may be adjusted so that the chromium oxide layer can be appropriately dissolved and the chromium plating layer is not dissolved.
  • a hydrofluoric acid aqueous solution having a concentration of 1 to 10 mass%, a sulfuric acid aqueous solution having a concentration of 1 to 30 mass%, or the like is used.
  • the halogen is contained in the chromium oxide layer by using the acid solution containing halogen. It was confirmed that the presence of halogen suppressed the formation of the chromium oxide layer over time and the accompanying decrease in conductivity over time.
  • halogens include one or more of fluorine (F), chlorine (Cl), bromine (Br) and iodine (I). Among them, it is preferable to use fluorine (F) because it has little effect on pH when ionized in a liquid.
  • the acid solution containing halogen for example, a hydrofluoric acid aqueous solution having a concentration of 1 to 10% by mass, a mixed aqueous solution of iron (III) chloride and hydrochloric acid, or the like is used.
  • Hydrofluoric acid is preferably used because it can be obtained as a fluoride having high chemical stability even when a halogen is contained in the chromium oxide layer.
  • the thickness of the chromium oxide layer on the surface of the steel material can be reduced by performing the surface treatment with such an acid aqueous solution or an acid aqueous solution containing halogen.
  • the thickness of the chromium oxide layer after surface treatment is set to less than 20 nm.
  • the preferred thickness is 17 nm or less, and the more preferable thickness is 15 nm or less.
  • the thickness of the chromium oxide layer after the surface treatment is preferably 0.5 nm or more, more preferably 1 nm or more.
  • the thickness of the chromium oxide layer is measured, for example, by X-ray photoelectron spectroscopy (XPS).
  • XPS X-ray photoelectron spectroscopy
  • O measurement peak of oxygen
  • the treatment conditions concentration, treatment time, treatment temperature, etc.
  • the treatment temperature is about 25 to 60 ° C. and the treatment time is about 10 to 100 seconds. It is preferable to make appropriate adjustments in consideration of other conditions and the like.
  • halogen in the chromium oxide layer is preferably 0.01 to 5 atomic% (at%).
  • halogen content can be appropriately adjusted depending on the surface treatment conditions.
  • a material in which at least a predetermined chromium plating layer and a chromium oxide layer are sequentially formed on the surface of a steel material as a base material is referred to as a "base material".
  • the composite material of the present embodiment includes a conductive carbon layer on at least one side of the base material.
  • the carbon layer contains a carbonaceous material and a matrix resin made of a thermoplastic resin or a thermosetting resin.
  • the thickness of the carbon layer is 0.1 mm to 3.0 mm. If the thickness of the carbon layer is less than 0.1 mm, sufficient corrosion resistance may not be obtained. On the other hand, if the thickness exceeds 3.0 mm, for example, when a composite material is used as a separator for a fuel cell, there is a risk of affecting high integration, flexibility, and the like.
  • the lower limit of the thickness of the carbon layer is preferably 0.15 mm, more preferably 0.2 mm.
  • the upper limit of the thickness of the carbon layer is preferably 2.5 mm, more preferably 2.0 mm.
  • the carbonaceous material may be any as long as it has conductivity, and its properties are not limited.
  • any one or a mixture of two or more selected from powders such as natural graphite powder, artificial graphite powder, expanded graphite powder, expanded graphite powder, scaly graphite powder, and spheroidal graphite powder can be mentioned. ..
  • at least expanded graphite powder and / or expanded graphite powder is contained from the viewpoint of flexibility and conductivity.
  • the content of the expanded graphite powder and / or the expanded graphite powder is preferably 4% by volume or more and less than 51% by volume in the mixed powder of the carbonaceous powder and the resin powder, and 5% by volume or more and less than 21% by volume.
  • the flexibility may decrease.
  • the volume is 51% by volume or more, the resin that contributes to the adhesion between the particles or between the particles and the metal plate may not function well, and the contact resistance may increase.
  • the true specific gravity of the expanded graphite powder and / or the expanded graphite powder is 2.2 g, which is the same as that of other graphite powders. It can be calculated as / cm 3 , preferably 5% by mass or more and less than 73% by mass, and more preferably 7% by mass or more and less than 30% by mass.
  • the lower limit of the average particle size is preferably 4 ⁇ m, more preferably 10 ⁇ m.
  • the upper limit of the average particle size is preferably 200 ⁇ m, more preferably 30 ⁇ m.
  • the particle size of the carbonaceous powder is an average particle represented by a value of D 50 (cumulative 50% by volume) calculated by a particle size counter of a laser diffraction type particle size distribution measuring device (for example, "Mastersizer 2000" manufactured by Malvern). Refers to the diameter.
  • the matrix resin may be a thermoplastic resin or a thermosetting resin.
  • the thermoplastic resin is not particularly limited, but is preferably polypropylene resin (PP), polyethylene resin (PE), polyamide resin (PA), polyphenylene sulfide resin (PPS), polymethylpentene resin (PMP), and polyetheretherketone. From the group consisting of resin (PEEK), polyphenylene ether resin (PPE), liquid crystal polymer resin (LCP), polyamideimide resin (PAI), polysulfone resin (PSU), polyethylene terephthalate resin (PET) and polybutylene terephthalate resin (PBT). Any one or a mixture of two or more selected may be mentioned.
  • the thermosetting resin is not particularly limited, but preferably any one or a mixture of two or more selected from the group consisting of phenol resin and epoxy resin can be mentioned.
  • the polyolefin resin such as PP, PE, PMP
  • a modified polyolefin resin in which a part or all of the unsaturated carboxylic acid or a derivative thereof is grafted on the polyolefin resin. ..
  • a modified polyolefin resin it is possible to improve the flexibility of the carbon layer and the composite material provided with the carbon layer, the adhesion to the base material, and the adhesion to the carbonaceous material. Be expected. In addition, this is preferable because the contact resistance is reduced.
  • the amount of graft (graft ratio) in the entire modified polyolefin resin is preferably 0.05 to 15% by mass, more preferably 0.1 to 10% by mass, and further preferably 0.1 to 3% by mass.
  • Specific examples of the unsaturated carboxylic acid or a derivative thereof used for grafting to a polyolefin resin before modification include acrylic acid, methacrylic acid, maleic acid, itaconic acid, citraconic acid, mesaconic acid, and maleic anhydride.
  • derivatives such as acid halide, amide, imide, and ester of the unsaturated carboxylic acid can also be used.
  • unsaturated dicarboxylic acids or acid anhydrides thereof are preferable, and maleic anhydride or hymic anhydride is particularly preferable.
  • Such an unsaturated carboxylic acid or a derivative thereof may be used alone, or a combination of two or more thereof may be used.
  • halogen group chlorine or bromine can be preferably used.
  • the volume ratio (C / R) of the carbonaceous material (C) and the matrix resin (R) in the carbon layer is preferably 6/4 to 9/1, more preferably 7/3 to 8/2. is there. If the volume ratio (C / R) of the carbonaceous material (C) and the matrix resin (R) is smaller than 6.4, the ratio of the carbonaceous material is low, which may affect the conductivity. On the other hand, if the volume ratio (C / R) is larger than 9/1, the ratio of the matrix resin is low, which may affect the flexibility, corrosion resistance and flexibility.
  • the method of forming the carbon layer is not particularly limited.
  • a method of filling the surface of a base material with a mixture containing a carbonaceous material (carbonaceous powder, etc.) and a matrix resin (resin powder, etc.) and hot-pressing, or a slurry in which the resin powder and the carbonic powder are dispersed in a solvent. Is applied to the surface of the base material using a doctor blade or the like, dried, and then hot-pressed.
  • a powder mixture containing a carbonaceous powder and a resin powder is warmly compression-molded (hot-pressed) to prepare a sheet-shaped carbon layer in advance, and the obtained sheet-shaped carbon layer is reapplied to the surface of the base material. It is better to use the hot press method of hot pressing and laminating.
  • the adhesive layer may be formed on the surface of the base material before the formation of the carbon layer (adhesive layer forming step). In that case, a carbon layer is formed via the adhesive layer.
  • a carbon layer is formed via the adhesive layer.
  • the adhesion between the base material and the carbon layer is improved.
  • the surface of the base material is coated with the adhesive layer, the durability against a corrosive environment when used as a fuel cell is improved, for example. If the thickness of the adhesive layer is too small, the adhesive strength may be insufficient. If the thickness is too large, the conductivity of the composite material may be insufficient.
  • the thickness of the adhesive layer is preferably 0.1 ⁇ m or more and 10 ⁇ m or less.
  • a preferable adhesive composition is one containing a modified polyolefin resin in which a part or all of an unsaturated carboxylic acid or a derivative thereof is grafted to a polyolefin resin (see, for example, JP-A-2005-146,178).
  • a modified polyolefin resin in which a part or all of an unsaturated carboxylic acid or a derivative thereof is grafted to a polyolefin resin
  • an adhesive composition containing an adhesive polyolefin resin (trade name: Admer manufactured by Mitsui Chemicals, Inc.) and an adhesive composition containing a modified polyolefin resin graft-modified with an unsaturated carboxylic acid (Mitsui Chemicals, Inc.).
  • Product name: Unistor and the like.
  • An adhesive composition (trade name: Toyobo Co., Ltd.) containing a modified polyolefin resin graft-modified with halogen is also used.
  • 5wt% -phenol resin adhesive composition solvent: isopropyl alcohol, phenol resin: product name manufactured by Lignite Co., Ltd .: AH-1148
  • epoxy resin adhesive composition product name manufactured by Nittetsu Chemical & Materials Co., Ltd.
  • a conductive carbon layer is formed on at least one surface of the plate-shaped base material to produce the composite material according to the present embodiment.
  • the contact resistance of the composite material of the present embodiment is preferably 10 m ⁇ ⁇ cm 2 or less, more preferably 5 m ⁇ ⁇ cm 2 or less, and further preferably 3 m ⁇ ⁇ cm 2 or less. Furthermore, it is preferable that the contact resistance does not substantially change in an environment corresponding to the usage environment of the fuel cell.
  • the composite material of this embodiment is excellent in conductivity (low contact resistance), corrosion resistance, and adhesion between the base material and the carbon layer.
  • the composite material of the present embodiment is suitable for applications such as a separator for a fuel cell such as a polymer electrolyte fuel cell, a current collector plate for a redox flow type secondary battery, and a gasket and packing for a petroleum refining / petrochemical plant. Used.
  • a separator for a polymer electrolyte fuel cell as illustrated in FIG. 5, two MEAs consisting of a polymer electrolyte membrane 6, an anode (fuel electrode) 7 and a cathode (oxidizing agent electrode) 8 are provided.
  • the configuration 10 sandwiched between the fuel cell separators 5 via the gasket 9 is used as a unit cell, and dozens to hundreds of these can be laminated to form a stack.
  • the steel material used as the base material for the base material was prepared as follows. That is, 150 kg of steel having a chemical composition of a to c (unit: mass%, the balance is Fe and impurities) as shown in Table 1 below was melted in a high-frequency induction heating type vacuum melting furnace and ingot into an ingot. .. The obtained 150 kg ingot was hot forged at 1220 ° C., cut, and then hot rolled at 1220 ° C. and annealed at 1180 ° C. Further, cold rolling was performed at 1080 ° C. and annealing was performed at 1080 ° C. to obtain steel foils a to c having a thickness of 50 ⁇ m.
  • the obtained steel materials a to c were chrome-plated under the following conditions. That is, a chrome-plated bath (bath composition: chromic acid 100 g / L, sulfuric acid 1.0 g / L, bath temperature 50 ° C.) was prepared, and each of the steel materials a to c was immersed therein for electroplating. The current density was 20 A / dm 2 , and the electrolysis time was 10 seconds.
  • a chrome-plated steel material having a chrome-plated layer having a thickness of about 0.1 ⁇ m formed on the surfaces of the steel materials a to c was obtained. The resulting chromium-plated steel material was kept in the air for several days.
  • a treatment aqueous solution As a treatment aqueous solution, a mixed aqueous solution of hydrochloric acid (HCl) and iron chloride (FeCl 3 ) (HCl: 0.9 mol / L, FeCl 3 : 2.3 mol / L, 40 ° C) was used, and chrome plating was applied thereto. The steel material was immersed (immersion time is shown in Table 2). The steel material taken out from the treated aqueous solution was ultrasonically cleaned in ultrapure water and then dried with cold air.
  • HCl hydrochloric acid
  • FeCl 3 iron chloride
  • An adhesive layer was formed on the surface of the obtained base material to obtain a base material with the adhesive layer. Specifically, using a tabletop coater, the adhesive composition was applied to the surface of the substrate so that the coating thickness was 10 ⁇ m, and dried at room temperature for 10 minutes to form an adhesive layer.
  • the adhesive composition was selected according to the type of matrix resin used in the carbon layer described later. That is, when polypropylene resin (PP) was used as the matrix resin, a modified polyolefin resin adhesive (trade name: Unistor manufactured by Mitsui Chemicals, Inc.) was used.
  • phenol resin (PF) is used as the matrix resin
  • a phenol resin adhesive phenol resin manufactured by Lignite Co., Ltd., trade name: AH-1148 in which the phenol resin is dissolved in isopropyl alcohol so as to be 5 wt% is used. There was.
  • -Type 1 (Test Examples 1 to 3 and Test Examples 5 to 11): Spheroidal graphite powder (trade name: SG-BH manufactured by Ito Graphite Co., Ltd., average particle size: 20 ⁇ m) and expanded graphite powder (trade name: EC100, average particle size: 160 ⁇ m manufactured by Ito Graphite Co., Ltd.) are used as carbonaceous materials. did.
  • matrix resin polypropylene resin (PP) powder (trade name: Flowbren HP-8522 manufactured by Sumitomo Seika Chemical Co., Ltd.), which is a thermoplastic resin, was used.
  • the spheroidal graphite powder was mixed in an amount of 60% by volume, the expanded graphite powder in an amount of 10% by volume, and the polypropylene resin powder in an amount of 30% by volume to obtain a powder mixture.
  • 1.4 g of this powder mixture (Test Examples 1 to 3, Test Examples 6 and 9 to 11; the thickness of the carbon layer after the present press is about 0.30 mm to 0.37 mm), 0.2 g (test) Example 5; The thickness of the carbon layer after the main press is about 0.05 mm) or 0.4 g (Test Examples 7 and 8; The thickness of the carbon layer after the main press is about 0.11 mm to 0.12 mm. ) using.
  • Each powder mixture is evenly charged into the female mold (50 x 50 x 20 mm) of the press device (tabletop hot press MP-SCL manufactured by Toyo Seiki Seisakusho Co., Ltd.) shown in FIG. 2, and the hot press (pressure) as a pre-press. : 2 MPa, temperature: 180 ° C.) to obtain a carbon layer (reference numeral 3).
  • the hot press pressure as a pre-press. : 2 MPa, temperature: 180 ° C.
  • the press apparatus is used to obtain the present press.
  • Hot pressed was performed. This press was performed at a pressure of 5 MPa (reference numeral P) and a heating temperature of 180 ° C. (reference numeral T) for 10 minutes. In this way, a composite material was obtained.
  • a carbon layer was formed in the same manner as in Type 1 except that the type of the matrix resin, the heating temperature in the pre-press, and the heating temperature in the main press were as follows to obtain a composite material.
  • the matrix resin phenol resin (PF) powder (trade name: AH-1148 manufactured by Lignite Co., Ltd.), which is a thermosetting resin, was used.
  • the heating temperature in the prepress was 80 ° C.
  • the heating temperature in this press was 150 ° C.
  • the powder mixture weighed 1.56 g.
  • the thickness of the carbon layer after this pressing was about 0.34 mm.
  • the sputtering conditions were Ar + for the ion species, 2 kV for the accelerating voltage, and 3.9 nm / min (SiO 2 conversion) for the sputtering rate.
  • each of the obtained composite materials was processed into a 2 cm ⁇ 2 cm test piece. The test piece was immersed in a 10 mass% NaOH aqueous solution for 30 minutes to remove the carbon layer.
  • the thickness of the chromium plating layer, the thickness of the chromium oxide layer, and the halogen in the chromium oxide layer were measured. The thickness of the chrome-plated layer is measured using the depth at which metallic chromium (Cr) begins to be detected by XPS measurement (depth from the outermost surface) as a guide.
  • the depth at which the peak intensity of the metal Cr is maximized (maximum peak depth) can be grasped. Therefore, before and after this maximum peak depth, 10% of the maximum peak intensity of the metal Cr is obtained.
  • the depth at which the intensity of the above was detected was defined as the start depth and the end depth, respectively.
  • the range from the start depth to the end depth was defined as the thickness of the chrome plating layer.
  • the thickness of the chromium oxide layer is measured using the depth (depth from the outermost surface) at which the bond (Cr-O) between Cr and oxygen (O) begins to be detected by XPS measurement as a guide.
  • the depth at which the peak intensity of Cr-O is maximized (maximum peak depth) can be grasped, so that the maximum Cr-O is before and after this maximum peak depth.
  • the depth at which 10% of the peak intensity was detected was defined as the start depth and the end depth, respectively.
  • the range from the start depth to the end depth was defined as the thickness of the chromium oxide layer. The results obtained are shown in Table 2.
  • the test piece was immersed in a fuel cell simulated environment, and the corrosion resistance was evaluated by the presence or absence of a precipitate in the solution. Specifically, first, a 20 mm ⁇ 20 mm test piece was cut out from each composite material. This test piece was immersed in a sulfuric acid solution (pH 3) at 80 ° C. containing 30 ppm chloride ion (Cl ⁇ ) for 240 hours. After the immersion, the presence or absence of a precipitate in the solution was confirmed and evaluated according to the following criteria. The results obtained are shown in Table 3 below. ⁇ : No precipitate ⁇ : No precipitate, but discoloration is seen in the solution ⁇ : With precipitate
  • FIG. 4 is a diagram showing a configuration of a device for measuring the contact resistance of the test material, and the contact resistance was measured using this device.
  • a 15 mm ⁇ 15 mm test piece was cut out from each composite material.
  • This test piece (reference numeral 14) was sandwiched between a pair of carbon papers (reference numeral 15) [TGP-H-90 manufactured by Toray Industries, Inc.] used as a gas diffusion layer for a fuel cell, and this was gold-plated 1. It was sandwiched between a pair of platinum electrodes (reference numeral 16).
  • the area of each carbon paper 15 was 1 cm 2 .
  • the composite materials according to Test Examples 1, 3, 4, 7 and 10 to 11 provided a predetermined chromium plating layer, chromium oxide layer and carbon layer, and the chromium oxide layer contained halogen. These composite materials had good contact resistance (conductivity), corrosion resistance, and adhesion between the base material and the carbon layer immediately after the composite material was produced and after 30 days had passed.
  • the composite material according to Test Example 2 was inferior in corrosion resistance because it did not have a chromium plating layer and a chromium oxide layer associated therewith. In addition, the adhesion between the base material and the carbon layer was also inferior.
  • the composite material according to Test Example 5 in which the thickness of the carbon layer was small was inferior in corrosion resistance and adhesion after the durability test.
  • the composite material according to Test Example 8 provided a predetermined chromium plating layer, chromium oxide layer and carbon layer, but the chromium oxide layer did not contain halogen.
  • This composite material was excellent in corrosion resistance and adhesion between the base material and the carbon layer, had low contact resistance immediately after the composite material was produced, and was excellent in initial conductivity. However, the contact resistance increased 30 days after the production of the composite material. It is presumed that this is because the chromium oxide layer does not have halogen, and the thickness of the chromium oxide layer increases with time.

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PCT/JP2020/010677 2019-03-22 2020-03-12 複合材及びその製造方法、並びに当該複合材を用いた燃料電池用のセパレータ、セル及びスタック WO2020195862A1 (ja)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5616698A (en) * 1979-07-23 1981-02-17 Nippon Kokan Kk <Nkk> Preparation of electrolytic chromate treated steel sheet having superior wet adhesive property
JP2016100177A (ja) * 2014-11-20 2016-05-30 株式会社プラズマイオンアシスト 燃料電池用セパレータ又は燃料電池用集電部材、及びその製造方法
JP2017071219A (ja) * 2015-10-05 2017-04-13 新日鉄住金マテリアルズ株式会社 ステンレス鋼板カーボン複合材及びその製造方法
WO2018150046A1 (de) * 2017-02-20 2018-08-23 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Bipolarplatte für brennstoffzellen sowie ein herstellungsverfahren

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JP2011134653A (ja) 2009-12-25 2011-07-07 Toyota Motor Corp 燃料電池用セパレータ、燃料電池用ガス流路層とこれらの製造方法
KR101446411B1 (ko) 2013-01-22 2014-10-07 (주)제이 앤 엘 테크 스테인레스스틸을 모재로 한 내식성 및 전도성 나노 카본 코팅 방법 및 그에 따른 연료전지분리판

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5616698A (en) * 1979-07-23 1981-02-17 Nippon Kokan Kk <Nkk> Preparation of electrolytic chromate treated steel sheet having superior wet adhesive property
JP2016100177A (ja) * 2014-11-20 2016-05-30 株式会社プラズマイオンアシスト 燃料電池用セパレータ又は燃料電池用集電部材、及びその製造方法
JP2017071219A (ja) * 2015-10-05 2017-04-13 新日鉄住金マテリアルズ株式会社 ステンレス鋼板カーボン複合材及びその製造方法
WO2018150046A1 (de) * 2017-02-20 2018-08-23 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Bipolarplatte für brennstoffzellen sowie ein herstellungsverfahren

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