GB2464707A - Ion - Conducting Membrane Structures - Google Patents
Ion - Conducting Membrane Structures Download PDFInfo
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- GB2464707A GB2464707A GB0819402A GB0819402A GB2464707A GB 2464707 A GB2464707 A GB 2464707A GB 0819402 A GB0819402 A GB 0819402A GB 0819402 A GB0819402 A GB 0819402A GB 2464707 A GB2464707 A GB 2464707A
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- ion
- conducting membrane
- conducting
- membrane structure
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- 239000012528 membrane Substances 0.000 title claims abstract description 217
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 35
- 229920000642 polymer Polymers 0.000 claims abstract description 17
- 239000004215 Carbon black (E152) Substances 0.000 claims abstract description 7
- 229930195733 hydrocarbon Natural products 0.000 claims abstract description 7
- 150000002430 hydrocarbons Chemical class 0.000 claims abstract description 7
- 239000003054 catalyst Substances 0.000 claims description 19
- 239000010411 electrocatalyst Substances 0.000 claims description 19
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 8
- BDHFUVZGWQCTTF-UHFFFAOYSA-N sulfonic acid Chemical class OS(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-N 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 6
- 238000000354 decomposition reaction Methods 0.000 claims description 4
- 229920000554 ionomer Polymers 0.000 claims description 4
- 239000002516 radical scavenger Substances 0.000 claims description 3
- 239000002253 acid Substances 0.000 claims 1
- -1 polyethylene Polymers 0.000 abstract description 15
- 239000000446 fuel Substances 0.000 abstract description 11
- 229920001343 polytetrafluoroethylene Polymers 0.000 abstract description 7
- 239000004810 polytetrafluoroethylene Substances 0.000 abstract description 7
- 239000002033 PVDF binder Substances 0.000 abstract description 5
- 229920002981 polyvinylidene fluoride Polymers 0.000 abstract description 5
- 239000004696 Poly ether ether ketone Substances 0.000 abstract description 4
- JUPQTSLXMOCDHR-UHFFFAOYSA-N benzene-1,4-diol;bis(4-fluorophenyl)methanone Chemical compound OC1=CC=C(O)C=C1.C1=CC(F)=CC=C1C(=O)C1=CC=C(F)C=C1 JUPQTSLXMOCDHR-UHFFFAOYSA-N 0.000 abstract description 4
- 229920002530 polyetherether ketone Polymers 0.000 abstract description 4
- 239000004698 Polyethylene Substances 0.000 abstract description 3
- 229920000573 polyethylene Polymers 0.000 abstract description 3
- 238000009792 diffusion process Methods 0.000 description 19
- 239000007789 gas Substances 0.000 description 19
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 15
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 12
- 229910052799 carbon Inorganic materials 0.000 description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 8
- 229920000412 polyarylene Polymers 0.000 description 8
- 229910052751 metal Inorganic materials 0.000 description 7
- 239000002184 metal Substances 0.000 description 7
- 239000004815 dispersion polymer Substances 0.000 description 6
- 238000005266 casting Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- 239000000758 substrate Substances 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000011236 particulate material Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 229920003935 Flemion® Polymers 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229920000557 Nafion® Polymers 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000003487 electrochemical reaction Methods 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 229920002313 fluoropolymer Polymers 0.000 description 2
- 239000004811 fluoropolymer Substances 0.000 description 2
- 239000002923 metal particle Substances 0.000 description 2
- 239000007800 oxidant agent Substances 0.000 description 2
- 230000001590 oxidative effect Effects 0.000 description 2
- 229910052697 platinum Inorganic materials 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 229910052707 ruthenium Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229920003934 Aciplex® Polymers 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- 229920000297 Rayon Polymers 0.000 description 1
- 229920004695 VICTREX™ PEEK Polymers 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 150000001721 carbon Chemical class 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000002322 conducting polymer Substances 0.000 description 1
- 229920001940 conductive polymer Polymers 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
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- 230000001419 dependent effect Effects 0.000 description 1
- 238000006056 electrooxidation reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
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- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 229910052741 iridium Inorganic materials 0.000 description 1
- GKOZUEZYRPOHIO-UHFFFAOYSA-N iridium atom Chemical compound [Ir] GKOZUEZYRPOHIO-UHFFFAOYSA-N 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052762 osmium Inorganic materials 0.000 description 1
- SYQBFIAQOQZEGI-UHFFFAOYSA-N osmium atom Chemical compound [Os] SYQBFIAQOQZEGI-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 229920001643 poly(ether ketone) Polymers 0.000 description 1
- 229920001657 poly(etheretherketoneketone) Polymers 0.000 description 1
- 229920001660 poly(etherketone-etherketoneketone) Polymers 0.000 description 1
- 229920002492 poly(sulfone) Polymers 0.000 description 1
- 229920006393 polyether sulfone Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000002964 rayon Substances 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 150000003457 sulfones Chemical class 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
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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
- H01M8/1041—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
-
- 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
- H01M8/102—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer
- H01M8/1023—Polymeric electrolyte materials characterised by the chemical structure of the main chain of the ion-conducting polymer having only carbon, e.g. polyarylenes, polystyrenes or polybutadiene-styrenes
-
- 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
- H01M8/1039—Polymeric electrolyte materials halogenated, e.g. sulfonated polyvinylidene fluorides
-
- 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
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Manufacturing & Machinery (AREA)
- Sustainable Development (AREA)
- Sustainable Energy (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Composite Materials (AREA)
- Fuel Cell (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
Abstract
An ion-conducting membrane structure comprising a first ion-conducting membrane 2 wherein said first ion-conducting membrane has a first face and a second face, characterised in that a second ion-conducting membrane 3 is applied to the first face of the first ion-conducting membrane is disclosed. Such membrane structures are suitable for use in electrochemical devices, for example fuel cells. The membranes may be formed from sulphonated or phosphonated hydrocarbon polymers and may comprise a reinforcing layer 4 of PTFE or PVDF or PEEK or polyethylene.
Description
ION-CONDUCTING MEMBRANE STRUCTURES
The present invention relates to a novel ion-conducting membrane structure, suitable for use in electrochemical devices, for example fuel cells.
A fuel cell is an electrochemical cell comprising two electrodes separated by an electrolyte. A fuel, such as hydrogen or an alcohol such as methanol or ethanol, is supplied to the anode and an oxidant, such as oxygen or air, is supplied to the cathode.
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 electrochemieal oxidation of the fuel at the anode and the electro chemical reduction of oxygen at the cathode.
In the proton exchange membrane fuel cell (PEMFC) and the direct methanol fuel cell (DMFC), the electrolyte is a solid polymeric membrane. The membrane is electronically insulating but ionically conducting. The membrane is typically proton conducting, and protons, produced at the anode, are transported across the membrane to the cathode, where they combine with oxygen to fonn water.
The principle component of a PEMFC or a DMFC is known as a membrane electrode assembly (MEA) and is essentially composed of five layers. The central layer is the polymer ion-conducting membrane. On either side of the ion-conducting membrane there is an electrocatalyst layer, containing an electrocatalyst designed for the specific electrolytic reaction. Finally, adjacent to each eleetrocatalyst layer there is a gas diffusion layer. The gas diffusion layer must allow the reactants to reach the electrocatalyst layer and must conduct the electric current that is generated by the electrochemical reactions. Therefore the gas diffusion layer must be porous and electrically conducting.
The MEA can be constructed by several methods. The electrocatalyst layer may be applied to the gas diffusion layer to form a gas diffusion electrode. Two gas diffusion electrodes can be placed either side of an ion-conducting membrane and laminated together to form the five-layer MEA. Alternatively, the electrocatalyst layer may be applied to both faces of the ion-conducting membrane to form a catalyst coated ion-conducting membrane. Subsequently, gas diffusion layers are applied to both faces of the catalyst coated ion-conducting membrane. Finally, an MEA can be formed from an ion-conducting membrane coated on one side with an electrocatalyst layer, a gas diffusion layer adjacent to that electrocatalyst layer, and a gas diffusion electrode on the other side of the ion-conducting membrane.
Typically tens or hundreds of MEAs are required to provide enough power for most applications, so multiple MEAs are assembled to make up a fuel cell staclc.
Field flow plates are used to separate the MEAs. The plates perform several functions: supplying the reactants to the MEAs, removing products, providing electrical connections and providing physical support.
Conventional ion-conducting membranes used in the PEMFCs and DMFCs are generally formed from perfluorinated sulphonic acid (PFSA) ionomers and the membranes formed from these ionoiners are sold under the trade names Nafion� (El.
DuPont de Nemours and Co.), Aeiplex� (Asahi Kasei) and Flemion� (Asahi Glass ElK). Such PFSA based ion-conducting membranes are suitably formed from a polymer having a side chain linked to the backbone of the polymer via an ether linkage. The typical structure of PFSA ionomers is shown below.
1CF2CF2)x -(CF-CF2)r (0CF CFzInrO-(CF2frSO3II CF3 Typical Structure of PFSA lonomer The PFSA ion-conducting membrane may contain a reinforcement to provide improved mechanical properties such as increased tear resistance and reduced dimensional change on hydration and dehydration. The preferred reinforcement may be based on, but not exclusively, a microporous web or fibres of a fluoropolymer such as polytetrafluoroethylene (PTFE), as described in US 6,254,978, EP 0814897 and US 6,110,330, or polyvinylidene fluoride (PVDF), or alternative-materials-such as PEEK or polyethylene.
In the DMFC there is a need to lower the methanol cross-over from anode to cathode through the solid polymeric membrane of the MEA without lowering the electrical efficiency or power density of the ftiel cell. This is required to raise the fttel efficiency and to prevent lowering of the MEA performance due to poisoning of the cathode by the methanol and the electrooxidation products generated at the cathode from the methanol. For widespread adoption of PEMFCs there is a need to provide both the required performance and durability from the solid polymeric membrane, but at decreased cost compared with traditional PFSA membranes.
It is therefore an object of the invention to provide an improved ion-conducting membrane structure for both PEMFC and DMFC.
Accordingly, the present invention provides an ion-conducting membrane structure comprising a first ion-conducting membrane wherein said first ion-conducting membrane has a first face and a second face, characterised in that a second ion-conducting membrane is applied to the first face of the first ion-conducting membrane.
In a preferred aspect of the invention, a third ion-conducting membrane is applied to the second face of the first ion-conducting membrane.
Suitably, the first, second and/or third ion-conducting membranes are independently selected from the group consisting of membranes formed from perfluorinated sulphonic acid (PFSA) ionomcrs and membranes formed from sulphonated or phosphonated hydrocarbon polymers.
Membranes formed from perfluorinated sulphonic acid ionomers include those as hereinbefore described and sold under the tradenames Nafion� (E.I. DuPont de Nemours and Co.), Aciplex� (Asahi Kasei) and Flemion� (Asahi Glass KIC).
Membranes formed from sulponated or phosphonated hydrocarbon polymers include those based on polyarylenes, including polyether sulfones (e.g. polyarylene sulfone (PSU, Udel), polyarylene ether sulfone (PBS, Vietrex�) and polycther ketones (e.g. polyarylene ether ether ketone (PEEK,Vietrex�), polyarylene ether ether ketone ketone (PEEKK, Hostatec�), polyarylene ether ketone, ether ketone ketone (PEKEKK, Ultrapec�) and polyarylene ether ketone (PEK, Victrex�)). Suitably, the membrane is a sulphonated polyarylene ether suiphone.
In a preferred aspect of the invention, the first ion-conducting membrane is of a different material to the second and, if present, third ion-conducting membranes.
Suitably, the second and, if present, third ion-conducting membranes are of the same material.
In a preferred embodiment of the, invention, the first ion-conducting membrane is a membrane fonned from a suiphonated or phosphonated hydrocarbon polymer and the second and, if present, third ion-conducting membranes are membranes formed from a perfluorinated sulphonic acid polymer.
In an alternative embodiment of the invention, the first ion-conducting membrane is a membrane formed from a pertluorinated sulphonic acid polymer and the second and third ion-conducting membranes are formed from a suiphonated or phosphonated hydrocarbon polymer.
The ion-conducting membrane structure suitably has a thickness of less than 200p.m. more suitably less than lOOitm, and more suitably less than 60p.m. Suitably, the ion-conducting membrane has a minimum thickness of 5p.m. The actual thickness will be dependent on its end use: for example in the PEMFC for automotive applications, the ion-conducting membrane structure is suitably approximately 30p.m thick; for stationary applications, the ion-conducting membrane structure is suitably approximately 50p.m thick; for DMFCs, the ion-conducting membrane structure is suitably approximately 50p.m thick and more suitably is approximately 30p.m thick.
The required thickness of the ion-conducting membrane structure would be readily known to the skilled person.
S
The total thickness of the second and, if present, third ion-conducting membrane is suitably less than the thickness of the first ion-conducting membrane.
Suitably, the total thickness of the second and, if present, third ion-conducting membrane is between 10 and 45% of the total thickness of the ion-conducting membrane structure. Suitably, the second and, if present, third ion-conducting membrane each have an individual thickness of less than 40jim, more suitably less than 25gm, preferably less than 20gm, for example from 2-10gm.
The ion-conducting membrane structure of the invention may be prepared by taking a first ion-conducting membrane, a second ion-conducting membrane and, if present, a third ion-conducting membrane. The first, second and, if present, third ion-conducting membranes are then laminated using techniques known to those skilled in the art, for example hot-pressing. Alternatively, a first ion-conducting membrane is formed by casting from a polymer dispersion or solution and the second and, if present, third ion-conducting membranes formed by casting from a polymer dispersion or solution directly onto one or both faces of the first ion-conducting membrane.
In a further embodiment of the invention, the ion-conducting membrane structure further comprises at least one reinforcing layer, for example a microporous web or fibres of a fluoropolymer such as PTFE as described in US 6,254,978, EP 0814897 and US 6,110,330, or polyvinylidene fluoride (PVDF), or alternative materials such as PEEK or polyethylene. Suitably, the reinforcing layer will be of PTFE. In one embodiment, the reinforcing layer crosses the interface of the first ion-conducting membrane and the second ion-conducting membrane. In a second embodiment, the reinforcing layer crosses the interface of the first ion-conducting membrane and the second ion-conducting membrane and crosses the interface of the first ion-conducting membrane and the third ion-conducting membrane. The reinforcing layer can either extend to one or both outer faces of the ion-conducting membrane structure or, alternatively, does not extend to one or both outer faces of the ion-conducting membrane structure such that at one or both outer faces of the ion-conducting membrane structure the ion-conducting membrane is not reinforced. To make a reinforced ion-conducting membrane structure, the reinforcing layer is partially embedded within the first ion-conducting membrane before solidification, Once the first ion-conducting membrane has solidified, the second and, if present, third ion-conducting membranes are cast onto one or both faces of the first ion-conducting membrane such that the reinforcing layer is also embedded within the second and/or third ion-conducting membranes. In the case, where the reinforcing layer does not extend to one or both of the outer surfaces of the ion-conducting membrane structure, sufficient ion-conducting membrane is cast so that once solidified, it extends beyond the reinforcing layer as required.
In a further aspect of the invention, and particularly for PEMFC applications, the ion-conducting membrane structure thither comprises a hydrogen peroxide decomposition catalyst and/or a radical scavenger as described in further detail in UK patent applications 0722913.1 and 0804185.7, both of wbieh are incorporated herein by reference. The hydrogen peroxide decomposition catalyst may be applied as a coating or embedded within the first, second and/or third ion-conducting membrane.
The ion-conducting membrane structure of the invention may be used in any electrochemical device requiring an ion-conducting, specifically proton-conducting, membrane, Accordingly, a further aspect of the invention provides an electrochemical device comprising an ion-conducting membrane structure as hereinbefore described.
Alternatively, there is provided the use of an ion-conducting membrane structure as hereinbefore described in an electrochemical device. In a preferred embodiment of the invention, the ion-conducting membrane structures are used in fuel cells, for example PEMFCs or DMFCs. Thus, the present invention further provides a catalyst-coated ion-conducting membrane structure comprising an ion-conducting membrane structure according to the invention and an electrocatalyst layer deposited on at least one side of the ion-conducting membrane structure. In one embodiment, the catalyst-coated ion-conducting membrane structure has an electrocatalyst layer deposited on both sides of the ion-conducting membrane structure.
The electrocatalyst layers comprise an electrocatalyst which may be a finely divided metal powder (metal black), or may be a supported catalyst wherein small metal particles are dispersed on electrically conducting particulate carbon supports.
The electrocatalyst metal (the primary metal) is suitably selected from (i) the platinum group metals (platinum, palladium, rhodium, ruthenium, iridium and osmium), or (ii) gold or silver.
The primary metal may be alloyed or mixed with one or more other precious metals such as ruthenium, or base metals such as molybdenum, tungsten, cobalt, chromium, nickel, iron, copper or an oxide thereof Preferably, the primary metal is platinum.
If the electrocatalyst is a supported catalyst, the loading of primary metal particles on the carbon support material is suitably in the range lO-9Owt%, preferably l5-75wt%.
The electrocatalyst layer(s) may suitably comprise other components, such as ion-conducting polymer, which is included to improve the ionic conductivity within the layer. In one embodiment, the electro catalyst layer(s) may further comprise one or more hydrogen peroxide decomposition catalysts andlor one or more radical scavenger as hereinbefore described. Preparation routes for preparing electrocatalyst layers comprising these components will be known to the skilled person.
A still further aspect of the invention provides a MBA comprising an ion-conducting membrane structure or a catalyst-coated ion-conducting membrane structure as hereinbefore described. The MEA may be made up in a number of ways including, but not limited to: (i) an ion-conducting membrane structure of the invention may be sandwiched between two gas diffUsion electrodes (one anode and one cathode); (ii) a catalyst-coated ion-conducting membrane structure of the invention coated on one side only by a catalyst layer and sandwiched between a gas diffusion layer and a gas diffusion electrode, the gas diffusion layer contacting the side of the ion-conducting membrane structure coated with the catalyst layer or; (iii) a catalyst-coated ion-conducting membrane structure of the invention coated on both sides with a catalyst layer and sandwiched between two gas diffusion layers.
The anode and cathode gas diffusion layers are suitably based on conventional gas diffusion substrates such as carbon paper (e.g. Toray� paper available from Toray Industries, Japan or U105 or Ul07 paper available from Mitsubishi Rayon, Japan), woven carbon cloths (e.g. the MK series of carbon cloths available from Mitsubishi
S
Chemicals, Japan) or non-woven carbon fibre webs (e.g. BLAT series of non-woven substrates available from B-TBK mc, USA; 142315 series available from Freudenberg FCCT KG, Gennany; or Sigracet� series available from SGL Technologies GmbH, Germany). The carbon paper, woven carbon cloth or non-woven carbon fibre web substrates are typically modified with a particulate material either embedded within the substrate or coated onto the planar faces, or a combination of both to form the gas diffusion layer. The particulate material is typically a mixture of carbon black and a polymer such as polytetrafluoroethylene (PTFE). Suitably the gas diffusion layers are between 100 and 300.tm thick. Preferably there is a layer of particulate material such as carbon black and PTFB on the faces of the gas diffusion layers that contact the electrocatalyst layers.
The MEA may further comprise components that seal andlor reinforce the edge regions of the MBA for example as described in W02005/020356. The MBA is assembled by conventional methods known to those skilled in the art.
A yet further aspect of the invention provides a fuel cell comprising an ion-conducting membrane structure, a catalyst-coated ion-conducting membrane structure or a MEA as hereinbefore described.
The ion-conducting membrane structure of the invention will now be described in more detail with reference to the figures.
Figure 1 is a schematic diagram of an ion-conducting membrane structure of the invention comprising a first ion-conducting membrane and a second ion-conducting membrane.
Figure 2 is a schematic diagram of an ion-conducting membrane structure of the invention comprising a first ion-conducting membrane, a second ion-conducting membrane and a third ion-conducting membrane.
Figures Ia, lb and 1 c each show an ion-conducting membrane structure (1) comprising a first ion-conducting membrane (2) and a second ion-conducting membrane (3). The ion-conducting membrane structure (I) shown in figure 1 a is not reinforced and may be prepared by casting a first ion-conducting membrane (2) from a polymer dispersion; once solidified a second ion-conducting membrane (3) is cast onto one face of the first ion-conducting membrane (2) from a polymer dispersion and allowed to solidify to form the ion-conducting membrane structure (I). The ion-conducting membrane structure (I) shown in Figure lb has a reinforcing layer (4) across the interface of the first ion-conducting membrane (2) and the second ion-conducting membrane (3). The reinforcing layer (4) does not extend to the outer faces of the ion-conducting membrane structure (I). The ion-conducting membrane structure (1) shown in Figure ic also has a reinforcing layer (4) across the interface of the first ion-conducting membrane (2) and the second ion-conducting membrane (3); however, the reinforcing layer (4) extends throughout the entire ion-conducting membrane structure (1). The ion-conducting membrane structures (1) of Figures lb and lc are prepared essentially as described for the structure of Figure la. However, to include the reinforcing layer (4), a reinforcing layer (4) is placed onto the wet or re-melted ion-conducting membrane (2) so that the polymer forming the ion-conducting membrane (2) is partially impregnated into the reinforcing layer (4) (Figure 1 b) or completely impregnated into the reinforcing layer (4) (Figure lc); one face of the reinforcing layer is allowed to remain outside the ion-conducting membrane (2). The second ion-conducting membrane (3) is then cast onto the face of the first ion-conducting membrane (2) having the reinforcing layer protruding therefrom and either extends beyond the exposed face of the reinforcing layer (4) to form the ion-conducting membrane structure (I) of Figure lb or is co-extensive with the exposed face of the reinforcing layer (4) to fonn the ion-conducting membrane structure (1) of Figure lc.
Figures 2a, 2b and 2c each show an ion-conducting membrane structure (1) comprising a first ion-conducting membrane (2), a second ion-conducting membrane (3) and a third ion-conducting membrane (5). The ion-conducting membrane structure shown (1) in Figure 2a is not reinforced and may be prepared by casting a first ion- conducting membrane (2) from a polymer dispersion; once solidified a second ion-conducting membrane (3) is cast onto one face of the first ion-conducting membrane (I) from a polymer dispersion and allowed to solidify, followed by casting of a third ion-conducting membrane (5) onto the other face of the first ion-conducting membrane (2) and allowed to solidify to form the ion-conducting membrane structure (1). The ion-conducting membrane structure (I) shown in Figure 2b has a reinforcing layer (4) across the interface of the first ion-conducting membrane (2) and the second ion-conducting membrane (3) and across the interface of the first ion-conducting membrane (2) and the third ion-conducting membrane (5). The reinforcing layer (4) does not extend to the outer faces of the ion-conducting membrane structure (1). The ion-conducting membrane structure (1) shown in Figure 2c also has a reinforcing layer (4) across the interface of the first ion-conducting membrane (2) and the second ion-conducting membrane (3) and across the interface of the first ion-conducting membrane (2) and the third ion-conducting membrane (5); however, the reinforcing layer 4) extends throughout the entire ion-conducting membrane structure (1). The ion-conducting membrane structures (I) of Figures 2b and 2c are prepared essentially as described for the structure of Figure 2a. However, to include the reinforcing layer (4), a reinforcing layer (4) is placed onto the wet or re-melted ion-conducting membrane (2) so that the polymer forming the ion-conducting membrane (2) is completely impregnated into the reinforcing layer (4); both faces of the reinforcing layer (4) remain outside the first ion-conducting membrane (2). The second ion-conducting membrane (3) is then cast onto a first face of the first ion-conducting membrane (2) and either extends beyond the exposed face of the reinforcing layer (4) (Figure 2b) or is co-extensive with the exposed face of the reinforcing layer (4) (Figure 2c); the second ion-conducting membrane (3) is allowed to solidify. The third ion-conducting membrane (5) is then cast onto the second face of the first ion-conducting membrane (2) and either extends beyond the exposed face of the reinforcing layer (4) (Figure 2b) or is co-extensive with the exposed face of the reinforcing layer (4) (Figure 2c); the third ion-conducting membrane (5) is allowed to solidify to form the ion-conducting membrane structure (1).
The skilled person will appreciate that there may be alternative methods of forming the ion-conducting membrane structures of the invention and membrane structure prepared by such alternative methods are also within the scope of the invention.
Claims (13)
- Claims I. An ion-conducting membrane structure comprising a first ion-conducting membrane wherein said first ion-conducting membrane has a first face and a second face, characterised in that a second ion-conducting membrane is applied to the first face of the first ion-conducting membrane.
- 2. Mi ion-conducting membrane structure according to claim 1, wherein a third ion-conducting membrane is applied to the second face of the first ion-conducting membrane.
- 3. An ion-conducting membrane structure according to claim I or claim 2, wherein the first, second andlor third ion-conducting membranes are independently selected from the group consisting of membranes formed from perfluorinated sulphonie acid (PFSA) ionomers and membranes formed from sulphonated or phosphonated hydrocarbon polymers.
- 4. An ion-conducting membrane structure according to any preceding claim, wherein the first ion-conducting membrane is of a different material to the second ion-conducting membrane.
- 5. An ion-conducting membrane structure according to any one of claims 2 to 4, wherein the second and third ion-conducting membranes are of the same material.
- 6. An ion-conducting membrane structure according to any preceding claim, wherein the first ion-conducting membrane is a membrane formed from a sulphonated or phosphonated hydrocarbon polymer.
- 7. An ion-conducting membrane structure according to any preceding claim, wherein the second ion-conducting membrane is formed from a perfluorinated sulphonic acid polymer.
- 8. An ion-conducting membrane structure according to any one of claims 2 to 7, wherein the third ion-conducting membrane is a membrane formed from a periluorinated sulphonic acid polymer.
- 9. An ion-conducting membrane structure according to any preceding claim, wherein the ion-conducting membrane structure comprises at least one reinforcing layer.
- 10. An ion-conducting membrane structure according to any preceding claim, wherein the ion-conducting membrane structure comprises a hydrogen peroxide decomposition catalyst and/or a radical scavenger.
- 11. A catalyst-coated ion-conducting membrane structure comprising an ion-conducting membrane structure as claimed in any one of claims 1 to 10 and an electrocatalyst layer deposited on at least one side of the ion-conducting membrane structure.
- 12. A membrane electrode assembly comprising an ion-conducting membrane structure as claimed in any one of claims 1 to 10.
- 13. A membrane electrode assembly comprising a catalyst-coated ion-conducting membrane structure as claimed in claim 11.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0819402A GB2464707A (en) | 2008-10-23 | 2008-10-23 | Ion - Conducting Membrane Structures |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0819402A GB2464707A (en) | 2008-10-23 | 2008-10-23 | Ion - Conducting Membrane Structures |
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| Publication Number | Publication Date |
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| GB0819402D0 GB0819402D0 (en) | 2008-11-26 |
| GB2464707A true GB2464707A (en) | 2010-04-28 |
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| GB0819402A Withdrawn GB2464707A (en) | 2008-10-23 | 2008-10-23 | Ion - Conducting Membrane Structures |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3691010A4 (en) * | 2017-09-29 | 2021-06-23 | Kolon Industries, Inc. | Polymer electrolyte membrane, method for manufacturing same, and membrane electrode assembly comprising same |
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|---|---|---|---|---|
| US5958616A (en) * | 1998-02-06 | 1999-09-28 | Lynntech, Inc. | Membrane and electrode structure for methanol fuel cell |
| KR20010093359A (en) * | 2000-03-28 | 2001-10-29 | 윤종용 | Fuel cell adopting multi-layered ion conductive polymer layer |
| WO2007048712A2 (en) * | 2005-10-24 | 2007-05-03 | Basf Se | Surface-structured membranes and membranes coated with a catalyst, and membrane electrode units made therefrom |
| WO2007062220A2 (en) * | 2005-11-23 | 2007-05-31 | Polyplus Battery Company | Li/air non-aqueous batteries |
| WO2007076595A1 (en) * | 2005-12-30 | 2007-07-12 | Tekion, Inc. | Composite polymer electrolyte membranes and electrode assemblies for reducing fuel crossover in direct liquid feed fuel cells |
-
2008
- 2008-10-23 GB GB0819402A patent/GB2464707A/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5958616A (en) * | 1998-02-06 | 1999-09-28 | Lynntech, Inc. | Membrane and electrode structure for methanol fuel cell |
| KR20010093359A (en) * | 2000-03-28 | 2001-10-29 | 윤종용 | Fuel cell adopting multi-layered ion conductive polymer layer |
| WO2007048712A2 (en) * | 2005-10-24 | 2007-05-03 | Basf Se | Surface-structured membranes and membranes coated with a catalyst, and membrane electrode units made therefrom |
| WO2007062220A2 (en) * | 2005-11-23 | 2007-05-31 | Polyplus Battery Company | Li/air non-aqueous batteries |
| WO2007076595A1 (en) * | 2005-12-30 | 2007-07-12 | Tekion, Inc. | Composite polymer electrolyte membranes and electrode assemblies for reducing fuel crossover in direct liquid feed fuel cells |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3691010A4 (en) * | 2017-09-29 | 2021-06-23 | Kolon Industries, Inc. | Polymer electrolyte membrane, method for manufacturing same, and membrane electrode assembly comprising same |
| US11444305B2 (en) | 2017-09-29 | 2022-09-13 | Kolon Industries, Inc. | Polymer electrolyte membrane, method for manufacturing same, and membrane electrode assembly comprising same |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0819402D0 (en) | 2008-11-26 |
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