WO2025257571A1 - Membrane conductrice d'ions - Google Patents

Membrane conductrice d'ions

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Publication number
WO2025257571A1
WO2025257571A1 PCT/GB2025/051307 GB2025051307W WO2025257571A1 WO 2025257571 A1 WO2025257571 A1 WO 2025257571A1 GB 2025051307 W GB2025051307 W GB 2025051307W WO 2025257571 A1 WO2025257571 A1 WO 2025257571A1
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WIPO (PCT)
Prior art keywords
ion
conducting
membrane
catalyst
hydrogen
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PCT/GB2025/051307
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English (en)
Inventor
Michael Andrew Yandrasits
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Johnson Matthey Hydrogen Technologies Ltd
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Johnson Matthey Hydrogen Technologies Ltd
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Publication of WO2025257571A1 publication Critical patent/WO2025257571A1/fr
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1067—Polymeric electrolyte materials characterised by their physical properties, e.g. porosity, ionic conductivity or thickness
    • 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
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1041—Polymer electrolyte composites, mixtures or blends
    • H01M8/1046—Mixtures of at least one polymer and at least one additive
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • C25B1/04—Hydrogen or oxygen by electrolysis of water
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B13/00—Diaphragms; Spacing elements
    • C25B13/04—Diaphragms; Spacing elements characterised by the material
    • C25B13/08—Diaphragms; Spacing elements characterised by the material based on organic materials
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
    • C25B9/23—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms comprising ion-exchange membranes in or on which electrode material is embedded
    • 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
    • H01M8/1004—Fuel cells with solid electrolytes characterised by membrane-electrode assemblies [MEA]
    • 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
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1041—Polymer electrolyte composites, mixtures or blends
    • H01M8/1046—Mixtures of at least one polymer and at least one additive
    • H01M8/1051—Non-ion-conducting additives, e.g. stabilisers, SiO2 or ZrO2
    • 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
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1041—Polymer electrolyte composites, mixtures or blends
    • H01M8/1053—Polymer electrolyte composites, mixtures or blends consisting of layers of polymers with at least one layer being ionically conductive
    • 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
    • H01M8/1016—Fuel cells with solid electrolytes characterised by the electrolyte material
    • H01M8/1018—Polymeric electrolyte materials
    • H01M8/1058—Polymeric electrolyte materials characterised by a porous support having no ion-conducting properties
    • 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
    • H01M2008/1095—Fuel cells with polymeric 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

Definitions

  • This invention relates to ion-conducting membranes containing additives which reduce degradation by the action of hydrogen radicals.
  • this invention relates to proton exchange membranes, and methods of manufacturing the same.
  • the ion-conducting membranes can be suitable for use in electrochemical devices such as fuel cells and/or electrolysers.
  • a fuel cell is an electrochemical cell comprising two electrodes separated by an electrolyte.
  • a fuel e.g. hydrogen, an alcohol such as methanol or ethanol, or formic acid
  • an oxidant e.g. oxygen or air
  • Electrochemical reactions occur at the electrodes, and the chemical energy of the fuel and the oxidant is converted to electrical energy and heat.
  • Electrocatalysts are used to promote the electrochemical oxidation of the fuel at the anode and the electrochemical reduction of oxygen at the cathode.
  • Fuel cells are usually classified according to the nature of the electrolyte employed. Often the electrolyte is a solid polymeric membrane, in which the membrane is electronically insulating but ionically-conducting. In the proton exchange membrane fuel cell (PEMFC) the membrane is proton-conducting, and protons, produced at the anode, are transported across the membrane to the cathode, where they combine with oxygen to form water.
  • PEMFC proton exchange membrane fuel cell
  • An electrolyser is an electrochemical device for electrolysing water to produce high purity hydrogen and oxygen. Electrolysers can operate in both alkaline and acidic systems. Those electrolysers that employ a solid proton-conducting polymer electrolyte membrane, or proton exchange membrane (PEM), are known as proton exchange membrane water electrolysers (PEMWEs). Those electrolysers that utilise a solid anion-conducting polymer electrolyte membrane, or anion exchange membrane (AEM), are known as anion exchange membrane water electrolysers (AEMWEs).
  • PEM proton exchange membrane water electrolysers
  • ion-conducting membranes used in PEMFCs or PEMWEs are generally formed from sulfonated fully-fluorinated polymeric materials (often generically referred to as perfluorinated sulphonic acid (PFSA) ionomers).
  • PFSA perfluorinated sulphonic acid
  • PFSA perfluorinated sulphonic acid
  • an ion-conducting membrane comprising:
  • the hydrogen radical scavenger typically has a rate constant for the reaction with a hydrogen radical (H ) of greater than or equal to 1 x 10 7 M' 1 s -1 .
  • a catalyst-coated membrane for a fuel cell or a water electrolyser comprising an ion-conducting membrane according to the disclosure, with a cathode catalyst layer applied to a first face of the membrane and I or an anode catalyst layer applied to a second face of the membrane.
  • a membrane-electrode assembly for a fuel cell or a water electrolyser comprising (i) an ion-conducting membrane according to the disclosure; or (ii) a catalyst- coated membrane according to the disclosure; and at least one of a gas diffusion layer or a porous transport layer.
  • a water electrolyser or a fuel cell comprising a catalyst-coated membrane according to the disclosure or a membrane-electrode assembly according to the disclosure.
  • a material having a rate constant for the reaction with a hydrogen radical (H ) of greater than or equal to 1 x 10 7 M' 1 s -1 for preventing degradation of an ionconducting membrane by hydrogen radicals.
  • a method of preventing degradation of an ion-conducting membrane by hydrogen radicals comprising using a material having a rate constant for the reaction with hydrogen radicals of greater than or equal to 1x10 7 M' 1 s -1 .
  • H2 hydrogen gas
  • H hydrogen radicals
  • the invention provides membranes with additives which selectively react with such radicals, without compromising the scavenging of other reactive species, such as peroxyl (HOO ), or hydroxyl (HO ) radicals, before they can react with the ion-conducting polymer in the membrane.
  • FIG. 1a and b provided diagrams of catalyst-coated membranes incorporating ionconducting membranes as disclosed herein.
  • Figure 2 is a chart providing data from an open-circuit voltage durability performance test carried out on an example of the invention and a comparative.
  • Figure 3 is a chart showing hydrogen cross over current over time after open-circuit voltage testing for an example of the invention and a comparative.
  • Figure 4 is a chart showing fluoride release rates over time, at the anode and cathode, after open-circuit voltage testing for an example of the invention and a comparative.
  • the ion-conducting membrane may be a fuel cell or water electrolyser ion-conducting membrane.
  • the ion-conducting polymer can be a proton-conducting polymer or an anion- conducting polymer, such as a hydroxyl anion-conducting polymer. Typically, a protonconducting polymer.
  • the ion-conducting membrane is suitably a proton exchange membrane.
  • the ion-conducting polymer comprises sulfonic acid groups.
  • the ionconducting polymer is a perfluorinated sulfonic acid ionomer, or a partially-fluorinated or nonfluorinated hydrocarbon sulfonic acid ionomer.
  • Such ion-conducting polymers optionally can contain partially or fully fluorinated vinyl ether. Such ion-conducting polymers can also optionally comprise bifunctional ion-conducting monomers.
  • suitable protonconducting polymers include partially- or fully-fluorinated sulphonic acid polymers, such as perfluorosulphonic acid ionomers (e.g.
  • Nafion® (Chemours), Aciplex® (Asahi Kasei), AquivionTM (Synesqo), Flemion® (Asahi Glass Co.); or ionomers based on a sulphonated hydrocarbon, otherwise known as hydrocarbon ion-conducting polymers, such as those available from FuMA-Tech GmbH as the fumapem® P, E or K series of products, JSR Corporation, Toyobo Corporation, and others including Pemion available from lonomr Innovations, Inc.
  • suitable anion-conducting polymers include A901 made by Tokuyama Corporation and Fumasep FAA from FuMA-Tech GmbH.
  • the ionconducting polymer has an equivalent weight of about 1100 or less, typically about 900 or less, or about 850 or less. Typically, the ion-conducting polymer has an equivalent weight of at least about 450.
  • the equivalent weight of the ion-conducting polymer may be readily measured using an acid titration following a hydroxide exchange. For example, a membrane sample may be vacuum dried at about 110 °C for 16 hours to obtain about 2g of the dried film. The film may then be immersed in about 30 mL of a 0.1 N NaOH solution to substitute sodium ions for protons in the membrane. Then titration by neutralisation is carried out, for example using 0.1 N hydrochloric acid, to determine the number of exchangeable protons, and therefore the EW may be calculated.
  • the hydrogen radical scavenger is a material which inhibits the degradation effects of hydrogen radicals on an ion-conducting membrane.
  • the hydrogen radical scavenger suitably has a rate constant for the reaction with a hydrogen radical (H ) of greater than or equal to 1 x 10 7 M' 1 s' 1 , typically greater than or equal to 1 x 10 8 M' 1 s -1 . Values which are greater than those for conventional oxygen based radical scavengers such as ceria.
  • This rate constant can be determined using a pulse radiolysis method employing a referenced scavenger such as disclosed in Gogolev, A.V. et al, International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry, 1991 , 37 (3), 531-535. In this method, an aqueous acid solution is subjected to an electron beam source to generate a hydrogen atom; e _ + H + -> H- [1]
  • reaction product of the hydrogen atom with the material of interest such as a Ag(l), V(V), Ce(IV), etc.
  • the material of interest such as a Ag(l), V(V), Ce(IV), etc.
  • an easily detected competitive hydrogen atom scavenger with known rate constant is added.
  • the product of H- addition o-phenanthroline has a visible light absorption at 680nm.
  • a 15 mM solution of cerium(IV) sulphate hydrate (Ce2(SO4)s x /7H2O) is prepared in 0.35 M sulfuric acid.
  • the solution is split into several aliquots and a competitive hydrogen radical scavenger, o-phenanthroline (Ph), is added in differing concentrations to make solutions with a [Ce(IV)]:[Ph] molar ratios from 2:1 to 12:1.
  • the samples are deaerated by bubbling with argon gas then exposed to a pulsed electron beam with energy of 5MeV for a duration of 2.3 microseconds.
  • the hydrogen radical scavenger may, for example, take the form of ions, particles, or complexes. Such particles may be nanoparticles e.g. having a size of 500 nm or less. Such particles may be supported or unsupported, for example supported on an inorganic metal oxide, for example silica or zirconia oxides.
  • Particle size is typically the Zave particle size measured by dynamic light scattering (typically in a Zetasizer from Malvern Panalytical) at an angle of 174 degrees. A solution with a weight percent in the range of and including 0.01 to 0.1 % by total weight of the solution may be used. About 1 mL of sample is placed in a glass cuvette and measurements run to give the Zave particle size for 5 measurements.
  • Suitable hydrogen radical scavenger materials include metal ions such as silver (Ag + ), palladium (Pd 2+ ), vanadium (V 5+ ), americium (Am 6+ ), dioxoamericium (AmC>2 2+ ), bismuth (Bi 3+ ), dichromate (C ⁇ O? 2- ), neptunium (Np 3+ ).
  • Suitable hydrogen radical scavenger materials include also include metal complexes, such as complexes of cobalt such as of the Co(ll) ion, or metal complexes of nickel such as of the Ni(ll) ion, e.g.
  • Typical materials are silver ions (Ag + ) and palladium ions (Pd 2+ ), suitably silver ions (Ag + ).
  • the hydrogen radical scavenger may be present in an amount of about 5 percent by weight or less, suitably about 1 percent by weight or less, relative to the total weight of the dry ionconducting membrane.
  • the hydrogen radical scavenger may be present in an amount of at least about 0.05 percent by weight, suitably at least about 0.1 percent by weight, relative to the total weight of the dry ion-conducting membrane.
  • the loading may alternatively be quantified in terms of moles per unit area and as such the hydrogen radical scavenger may be present in an amount of greater than or equal to about 0.001 micromoles/cm 2 .
  • the hydrogen radical scavenger may be present in an amount of less than or equal to 5 micromoles/cm 2 , typically less than or equal to about 2.5 micromoles/cm 2 .
  • the hydrogen radical scavenger may be uniformly distributed across the thickness of the ion-conducting membrane.
  • uniform it is meant that the amount of particles typically does not vary by more than ⁇ 50%, suitably by more than ⁇ 20%.
  • the material may also not be uniformly distributed. For example, there may be a variation in distribution in the z-direction, with a preference for the higher relative percentage closer to the hydrogen electrode i.e.
  • One way to achieve this is to have a sub-layer of the ion-conducting membrane which contains the hydrogen radical scavenger and is positioned closer to the anode than the cathode.
  • the sub-layer can be directly adjacent to the hydrogen electrode or closer to the hydrogen electrode side but not directly adjacent to the hydrogen electrode, e.g. with at least one further sub-layer between the hydrogen electrode and the sub-layer containing the hydrogen radical scavenger.
  • the ion-conducting membrane may also comprise a peroxide radical reducing additive, such as ceria. It will be noted that peroxide can decompose to form a range of radicals (O, OH, OOH) and the radical reducing additive may reduce the amount of one, more, or all of these radicals. If present, such a peroxide radical reducing additive is typically a separate and distinct entity from the hydrogen radical scavenger.
  • the ion-conducting membrane may also comprise a recombination catalyst.
  • a recombination catalyst is a catalyst which catalyses the reaction between hydrogen gas and oxygen gas to form water, thus minimise any hydrogen crossover through the membrane, to avoid hydrogen mixing with oxygen and associated safety concerns.
  • the recombination catalyst may comprise platinum or palladium, or consists essentially of platinum or palladium (i.e. the nanoparticles are platinum nanoparticles or palladium nanoparticles).
  • the recombination catalyst may be platinum alloyed with another element, for example a platinum-palladium alloy, a platinum-iridium alloy, a platinum cobalt alloy or a platinum-ruthenium alloy.
  • the ion-conducting membrane may further comprise: (c) a reinforcing layer which may be a porous polymer material, wherein the ion-conducting polymer is impregnated within the porous polymer material.
  • the reinforcing layer is typically planar.
  • the porous polymer material may be a fluoropolymer.
  • the porous polymer material may be selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyethersulfone (PES), poly(vinylidene fluoride-co- hexafluoropropylene) (PVDF-HFP), polyimides (PI), polyetherimide (PEI), poly(aryl ether ketone) (PAEK), poly(aryl ether sulfone), poly(phenylene sulfide) (PPS), polyvinylpyrrolidone (PVP) and polyether ether ketone (PEEK).
  • the porous polymer material may be expanded polytetrafluoroethylene (ePTFE).
  • the porous polymer material may also comprise a polymer backbone based on a nitrogen-containing heterocycle.
  • the nitrogen-containing heterocycle may comprise basic functional groups.
  • the nitrogen-containing basic functional groups can be nitrogen with a lone pair.
  • the polymer backbone can be derived from polybenzimidazoles, poly(pyridine)s, poly(pyrimidine)s, polybenzthiazoles, polyoxadiazoles, polyquinolines, polyquinoxalines, polythiadiazoles, polytriazoles, polyoxazoles, polybenzoxazoles, polythiazoles, polypyrazoles, and derivatives thereof.
  • the polymer backbone may be derived from a functionalised polyazole or a zwitterionic polyazole, such as a polybenzimidazole, polytriazole, polythiazole and polydithiazole and their derivatives; most suitably a polybenzimidazole. It will be understood by the skilled person that the polymer backbone may comprises more than one type of nitrogen-containing heterocycle, or a mixture of a nitrogencontaining heterocycles and other aliphatic or aromatic groups.
  • the porous polymer structure may comprise a porous mat of nanofibers.
  • the porous mat may be formed from entangled nanofibres.
  • the nanofibres are ionically non-conductive.
  • the nanofibres are devoid of sulphonic acid groups and/or phosphoric acid groups.
  • the nanofibres may comprise discrete nanofibres that are entwined.
  • the nanofibres can cross each other or be twisted with other nanofibres or itself.
  • the porous mat of nanofibres can be in the form of a non-woven fabric material.
  • the nanofibres may have a substantially random orientation in the plane of the reinforced ion-conducting membrane (i.e.
  • the nanofibres may have a diameter of 50-700 nm, suitably 200-600 nm or 250- 550 nm.
  • the length of the nanofibres is not material to the disclosure, but each nanofibre should be sufficiently long (for example several millimetres or centimetres) to be entangled, either with one or more other nanofibres or with itself.
  • the nanofibres may be spun nanofibres, i.e. the nanofibres are formed using a spinning technique. Examples of suitable spinning techniques include, but are not limited to, electrospinning and force spinning.
  • the reinforcing layer may also be a woven fabric, for example a woven PEEK fabric.
  • the reinforcing layer may have a maximum thickness of 100 % of the thickness of the reinforced ion-conducting membrane such as a maximum thickness of 90 %, 80 %, 70 %, 60 %, or 50 % of the thickness of the ion-conducting membrane.
  • the porous polymer material may have a minimum thickness of 5 % of the thickness of the ion-conducting membrane, such as a minimum thickness of 10 %, 15 %, 20 %, 25 % or 30 % of the thickness of the ion- conducting membrane.
  • the porous polymer material in the ion-conducting membrane may have a thickness in the range of and including 5 to 95 % of the thickness of the reinforced ionconducting membrane, such as a thickness in the range of and including 10 to 90 % or 20 to 80 % of the thickness of the reinforced ion-conducting membrane.
  • the ion-conducting membrane may contain more than one, for example two, reinforcing layer(s) each having ion-conducting polymer impregnated in at least a region thereof. It will be understood that, in the case that the reinforced ion-conducting membrane has more than one reinforcing layer the maximum and I or minimum thickness is the sum of the thickness of each porous polymer structure.
  • the thickness of the or each porous polymer structure, as a proportion of the reinforced ion-conducting membrane may be determined, for example, from a scanning electron microscope (SEM) image of a cross section of the reinforced ionconducting membrane.
  • SEM scanning electron microscope
  • the thickness of the ion-conducting membrane will depend on its intended use. For example, an ion-conducting membrane for a water electrolyser will typically be thicker than for a fuel cell but that may not always be the case.
  • the ion-conducting membrane may have a thickness of at least about 5 micrometres.
  • the ion-conducting membrane may have a thickness of at least about 6 micrometres, about 7 micrometres, about 8 micrometres, about 9 micrometres or at least about 10 micrometres.
  • the ion-conducting membrane may be prepared by a process comprising the steps of:
  • step (b) forming the ion-conducting membrane from the mixture produced in step (a).
  • the ion-conducting polymer is in a suspension or solution in a solvent and step (b) comprises forming the ion-conducting membrane from the suspension or solution.
  • the hydrogen radical scavenger is an ionic species, a skilled person will appreciate that it will be added to step (a) in the form of a salt. A skilled person can select an appropriate salt which is compatible with the process.
  • a catalyst-coated membrane comprising an ion-conducting membrane of the disclosure, with a cathode catalyst layer applied to a first face of the membrane and I or an anode catalyst layer applied to a second face of the membrane.
  • the catalyst layer comprises one or more electrocatalysts.
  • the one or more electrocatalysts may be independently a finely divided unsupported metal powder, or a supported catalyst wherein small nanoparticles are dispersed on a catalyst support, such as electrically conducting particulate carbon supports or a metal oxide such as titania.
  • the electrocatalyst metal may be selected from;
  • platinum group metals platinum, palladium, rhodium, ruthenium, iridium and osmium
  • a typical electrocatalyst metal is platinum, which may be alloyed with other precious metals or base metals.
  • a base metal is tin or a transition metal which is not a noble metal.
  • a noble metal is a platinum group metal (platinum, palladium, rhodium, ruthenium, iridium or osmium), gold or silver.
  • Suitable base metals include copper, cobalt, nickel, zinc, iron, titanium, molybdenum, vanadium, manganese, niobium, tantalum, chromium and tin.
  • Suitable base metals are nickel, copper, cobalt, and chromium. More suitable base metals are nickel, cobalt and copper.
  • the anode catalyst layer comprises iridium, such as iridium oxide or mixed oxides of iridium and another metal or metals.
  • the anode material can be formulated into an ink, suitably in an ion-conducting polymer, printed ex-situ onto a PTFE sheet, and transferred onto the membrane by hot pressing. Alternatively, the ink can be directly coated onto the membrane.
  • the anode catalyst layer comprises platinum, for example a platinum-on-carbon catalyst.
  • the anode material can be formulated into an ink, suitably in an ion-conducting polymer, printed ex-situ onto a PTFE sheet, and transferred onto the membrane by hot pressing.
  • the ink can be directly coated onto the membrane.
  • Sub-layer 6 contains the hydrogen radical scavenger and is positioned adjacent to the anode catalyst layer 2.
  • the sub-layer containing the hydrogen radical scavenger is positioned closer to the anode than the cathode, but is not directly adjacent to the anode with another sub-layer between the anode and the sub-layer containing the hydrogen radical scavenger.
  • a planar reinforcing component akin to that shown in Figure 1 A, and which bridges the two sub-layers, may be present but is not shown here.
  • a membrane electrode assembly comprising an ion-conducting membrane of the disclosure and a gas diffusion electrode and / or a porous transport layer on a first and/or second face of the ion-conducting membrane. Also provided is a membrane electrode assembly comprising a catalyst-coated ion-conducting membrane and a gas diffusion layer or porous transport layer present on the at least one of the catalyst layers.
  • the anode and cathode gas diffusion layers may be based on conventional gas diffusion substrates. Typical substrates include non-woven papers or webs comprising a network of carbon fibres and a thermoset resin binder (e.g.
  • the carbon paper, web or cloth may be provided with a further treatment prior to being incorporated into a MEA either to make it more wettable (hydrophilic) or more wet-proofed (hydrophobic). The nature of any treatments will depend on the type of fuel cell and the operating conditions that will be used.
  • the substrate can be made more wettable by incorporation of materials such as amorphous carbon blacks via impregnation from liquid suspensions, or can be made more hydrophobic by impregnating the pore structure of the substrate with a colloidal suspension of a polymer such as PTFE or polyfluoroethylenepropylene (FEP), followed by drying and heating above the melting point of the polymer.
  • a microporous layer may also be applied to the gas diffusion substrate on the face that will contact the catalyst layer.
  • the microporous layer typically comprises a mixture of a carbon black and a polymer such as polytetrafluoroethylene (PTFE).
  • the porous transport layer may be based on conventional porous transport substrates, such as a titanium mesh.
  • an electrochemical device comprising an ion-conducting membrane, a catalyst-coated membrane, or a membrane-electrode assembly of the disclosure.
  • the electrochemical device can be a fuel cell, such as a proton exchange membrane fuel cell.
  • the electrochemical device can be an electrolyser, such as a proton exchange membrane water electrolyser.
  • a material as defined herein, having a rate constant for the reaction with a hydrogen radical (H ) of greater than or equal to 1 x 10 7 M' 1 s -1 , typically greater than or equal to 1 x 10 8 M' 1 s -1 , for preventing degradation of an ion-conducting membrane by hydrogen radicals.
  • the material may be the hydrogen radical scavenger as defined herein.
  • the ionconducting membrane is as defined herein and can be used and incorporated into components as described herein.
  • Also provided is a method of preventing degradation of an ion-conducting membrane by hydrogen radicals comprising using a material, as defined herein, having a rate constant for the reaction with a hydrogen radical (H ) of greater than or equal to 1 x 10 7 M 1 s' 1 , typically greater than or equal to 1 x 10 8 M' 1 s'1.
  • H hydrogen radical
  • the material may be the hydrogen radical scavenger as defined herein.
  • the ion-conducting membrane is as defined herein and can be used and incorporated into components as described herein.
  • An ion-conducting membrane containing a silver ion hydrogen radical scavenger is prepared by initially preparing separate additive and ion-conducting polymer (ionomer) dispersions.
  • ionomer ion-conducting polymer
  • For the additive a 3 wt% AgNCh solution is prepared by dissolving AgNCh in mil li-Q H2O; for the ionomer, a 25 wt% PFSA (EW725) solution is prepared by dissolving the ionomer in a mix of EtOH and milli-Q H 2 O (EtOH:H 2 O 80:20 by weight).
  • a gas diffusion layer (Sigracet 22BB) was applied to each face of the catalyst-coated ion-conducting membrane to form a complete membrane electrode assembly.
  • the gas diffusion layer used was a carbon fibre paper with a hydrophobic microporous layer containing carbon and PTFE applied to the face in contact with the catalyst coated ion-conducting membrane.
  • the MEA was initially preconditioned for 54 hours at 80°C and 100% relative humidity, under a constant current density of 500 mA/cm 2 , with hydrogen supplied to the anode side at a rate of 0.7 SLPM (stoichiometry of 1.5), and air supplied to the cathode side at a rate of 1 .66 SLPM (stoichiometry of 2), both at an inlet pressure of 100 kPa.
  • polarisation curves were conducted by incrementally applying current densities ranging from 0 to 1.5 A/cm 2 under 80°C, 40% relative humidity and 50 kPa with holds of 12.5 minutes. Hydrogen was fed to the anode (stoichiometry of 1.5) and oxygen to the cathode (stoichiometry of 1.8).
  • LSV linear sweep voltammetry
  • fluoride release effluent water samples from the anode and cathode sides were collected and analysed by IC to determine fluoride levels after each OCV hold.
  • the fluoride release rate (FRR) was determined by dividing the quantity of fluoride by the duration of the OCV hold and the MEA active area.
  • Fig. 4 shows fluoride release rate at the anode and cathode after each OCV hold.

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Abstract

La présente invention concerne une membrane conductrice d'ions comprenant : (a) un polymère conducteur d'ions ; et (b) un piégeur de radicaux hydrogène.
PCT/GB2025/051307 2024-06-14 2025-06-13 Membrane conductrice d'ions Pending WO2025257571A1 (fr)

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EP1946400A2 (fr) 2005-10-28 2008-07-23 3M Innovative Properties Company Composantes de pile à combustible longue durée contenant des additifs à base d'oxyde de cérium
US20120052407A1 (en) * 2004-01-20 2012-03-01 E. I. Du Pont De Nemours And Company Processes for preparing stable proton exchange membranes and catalyst for use therein
US20200280074A1 (en) * 2017-09-29 2020-09-03 Kolon Industries, Inc. Radical scavenger, manufacturing method therefor, membrane-electrode assembly comprising same, and fuel cell comprising same
EP4040549A1 (fr) * 2019-09-30 2022-08-10 Kolon Industries, Inc. Dispersion d'ionomères ayant une stabilité de dispersion élevée, son procédé de production, et membrane échangeuse de protons produite au moyen de celui-ci

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JP2005005232A (ja) * 2003-06-16 2005-01-06 Matsushita Electric Ind Co Ltd 膜電極接合体およびそれを用いた固体高分子電解質型燃料電池
KR102510869B1 (ko) * 2020-07-15 2023-03-17 한국과학기술연구원 연료전지의 전해질막용 산화방지제 및 그의 제조방법

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US20120052407A1 (en) * 2004-01-20 2012-03-01 E. I. Du Pont De Nemours And Company Processes for preparing stable proton exchange membranes and catalyst for use therein
EP1946400A2 (fr) 2005-10-28 2008-07-23 3M Innovative Properties Company Composantes de pile à combustible longue durée contenant des additifs à base d'oxyde de cérium
US20200280074A1 (en) * 2017-09-29 2020-09-03 Kolon Industries, Inc. Radical scavenger, manufacturing method therefor, membrane-electrode assembly comprising same, and fuel cell comprising same
EP4040549A1 (fr) * 2019-09-30 2022-08-10 Kolon Industries, Inc. Dispersion d'ionomères ayant une stabilité de dispersion élevée, son procédé de production, et membrane échangeuse de protons produite au moyen de celui-ci

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F.D. ET AL., ECS TRANS., vol. 16, no. 2, 2008, pages 235
GOGOLEV, A.V. ET AL.: "International Journal of Radiation Applications and Instrumentation. Part C.", RADIATION PHYSICS AND CHEMISTRY, vol. 37, no. 3, 1991, pages 531 - 535
LINLET, JOURNAL OF POWER SOURCES, vol. 233, 2013, pages 98 - 106

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