CA2303507A1 - Process of forming a membrane electrode - Google Patents

Process of forming a membrane electrode Download PDF

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Publication number
CA2303507A1
CA2303507A1 CA002303507A CA2303507A CA2303507A1 CA 2303507 A1 CA2303507 A1 CA 2303507A1 CA 002303507 A CA002303507 A CA 002303507A CA 2303507 A CA2303507 A CA 2303507A CA 2303507 A1 CA2303507 A1 CA 2303507A1
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Prior art keywords
membrane
porous
solution
electrode
electrolyte
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French (fr)
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Mark K. Debe
Thao Ngoc Pham
Andrew J. Steinbach
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3M Co
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/86Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88Processes of manufacture
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/86Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88Processes of manufacture
    • H01M4/8878Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body
    • H01M4/8896Pressing, rolling, calendering
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25BELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B13/00Diaphragms; Spacing elements
    • C25B13/04Diaphragms; Spacing elements characterised by the material
    • C25B13/08Diaphragms; Spacing elements characterised by the material based on organic materials
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25BELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/17Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
    • C25B9/19Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
    • C25B9/23Cells 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
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid
    • G01N27/125Composition of the body, e.g. the composition of its sensitive layer
    • G01N27/127Composition of the body, e.g. the composition of its sensitive layer comprising nanoparticles
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00Fuel cells; Manufacture thereof
    • H01M8/10Fuel cells with solid electrolytes
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00Fuel cells; Manufacture thereof
    • H01M8/10Fuel cells with solid electrolytes
    • H01M8/1004Fuel cells with solid electrolytes characterised by membrane-electrode assemblies [MEA]
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B82NANOTECHNOLOGY
    • B82YSPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00Nanotechnology for materials or surface science, e.g. nanocomposites
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30Hydrogen technology
    • Y02E60/50Fuel cells
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product
    • YGENERAL 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
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00Metal working
    • Y10T29/49Method of mechanical manufacture
    • Y10T29/49002Electrical device making
    • Y10T29/49108Electric battery cell making
    • Y10T29/49112Electric battery cell making including laminating of indefinite length material
    • YGENERAL 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
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/31504Composite [nonstructural laminate]
    • Y10T428/3154Of fluorinated addition polymer from unsaturated monomers
    • YGENERAL 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
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/31504Composite [nonstructural laminate]
    • Y10T428/31721Of polyimide
    • YGENERAL 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
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/31504Composite [nonstructural laminate]
    • Y10T428/31725Of polyamide
    • YGENERAL 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
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/31504Composite [nonstructural laminate]
    • Y10T428/31855Of addition polymer from unsaturated monomers
    • Y10T428/31935Ester, halide or nitrile of addition polymer

Abstract

A method is provided for making a membrane electrode that employs a composite membrane, which include both a porous membrane and an ion conducting electrolyte, by partially filling a porous membrane with an ion conducting electrolyte to form a partially filled membrane and then compressing the partially filled membrane with electrode particles so as to remove void volume from the partially filled membrane and embed the electrode particles in the partially filled membrane. The membrane electrode of this invention is suitable for use in electrochemical devices, including proton exchange membrane fuel cells, electrolyzers, chlor-alkali separation membranes, and the like.

Description

PROCESS OF FORMING A MEMBRANE ELECTRODE
Field of the Invention This invention relates to a process of forming a membrane electrode assembly that comprises a composite membrane and is suitable for use in electrochemical devices, including proton exchange membrane fuel cells, electrolyzers, chlor-alkali separation membranes, sensors, and the like.
Background of the Invention Electrochemical devices, including proton exchange membrane fuel cells, electrolyzers, chlor-alkali separation membranes, and the like, have been constructed from membrane electrode assemblies (MEAs). Such MEAs comprise one or more electrode portions, which include a catalytic electrode material such as Pt or Pd, in contact with an ion conductive membrane. Ion conductive membranes (ICMs) are used in electrochemical cells as solid electrolytes. In a typical electrochemical cell, an ICM is in contact with cathode and anode electrodes, and transports ions such as protons that are formed at the anode to the cathode, allowing a current of electrons to flow in an external circuit connecting the electrodes.
MEAs are used in hydrogen/oxygen fuel cells. A typical MEA for use in a hydrogen/oxygen fuel cell might comprise a first Pt electrode portion, an ICM
comprising a proton-exchange electrolyte, and a second Pt electrode portion.
Such an MEA can be used to generate electricity by oxidation of hydrogen gas, as illustrated in the following reactions:
Pt (1st electrode) Pt (2nd electrode) l<i2 gas --->2e + 2H+ 2H+ (via electrolyte) ---> 2H+ + 2e' +'/2 Oz ---> g20 2e (via electric circuit) --->
In a typical hydrogen/oxygen fuel cell, the ions to be conducted by the membrane are protons. Importantly, ICMs do not conduct electrons/electricity, since this would render the fuel cell useless, and they must be essentially SUBSTITUTE SHEET (RULE 26) impermeable to fuel gasses, such as hydrogen and oxygen. Any leakage of the gasses employed in the reaction across the MEA results in waste of the reactants and inefficiency of the cell. For that reason, the ion exchange membrane must have low or no permeability to the gasses employed in the reaction.
ICMs also find use in chlor-alkali cells wherein brine mixtures are separated to form chlorine gas and sodium hydroxide. The membrane selectively transports sodium ions while rejecting chloride ions. ICMs also can be useful for applications such as diffusion dialysis, electrodialysis, and pervaporization and vapor permeation separations. While most ICMs transport cations or protons, membranes that are transportive to anions such as OH are known and commercially available.
Commercially-available ICMs are not entirely satisfactory in meeting the performance demands of fuel cells. For example, NafionTM membranes (DuPont Chemicals, Inc., Wilmington, DE) which are perfluorocarbon materials having a S03 anion, are inherently weak. NafionTM membranes are not generally available at thicknesses of less than 50 Vim. One reason is that NafionTM membranes that thin would require reinforcement, thus defeating the purpose of a thin membrane by increasing the overall thickness as well as increasing the electrical resistance of the membrane. While NafionTM membranes with lower equivalent weight can be used to obtain lower electrical resistance, lower equivalent weight membranes are structurally weaker and still would not obviate the need for reinforcement.
One means of constructing a reinforced membrane is to imbibe or infuse an ion-conductive material into a porous inert reinforcing membrane to make a composite membrane. For example, Gore-SelectTM membranes (W. L. Gore &
Associates, Inc., Elkton, MD) comprise a poly(tetrafluoroethylene) (PTFE) membrane having an ion-conductive or ion exchange liquid impregnated therein.
U. S. Patent No. 5,547,551 describes a PTFE membrane fully impregnated with NafionTM solution for use in fuel cells. Other inert membranes have been mentioned, such as polyolefins and poly(vinylidene fluoride), as suitable carriers for ion-conducting electrolytes.
Composite proton exchange membranes, comprising electrolytes immobilized in porous webs, have been shown to offer superior properties over SUBSTITUTE SHEET (RULE 26) single component membranes when used in fuel cells. The composite membranes can be made thinner and stronger while giving equivalent conductivity with less electrolyte, and have more dimensional stability even after becoming saturated with water. However, because the membranes employed are initially porous, the gas permeability of the resulting membrane depends in part on the degree to which the membrane is filled by the electrolyte.
These composite membranes are used in fuel cell MEAs that use conventional catalyst electrodes in the form of applied dispersions of either Pt fines or carbon supported Pt catalysts. These conventional catalysts are applied as a coating of ink or paste to either the composite membrane or to an electrode backing layer placed adjacent to the membrane. The ink or paste typically contains electrolyte in the form of an ionomer.
Various structures and means have been used to apply or otherwise bring a catalyst in contact with an electrolyte to form electrodes, e.g., cathodes and anodes.
1 S These "membrane electrode assemblies" (MEAs) can include: {a) porous metal films or planar distributions of metal particles or carbon supported catalyst powders deposited on the surface of the ICM; (b) metal grids or meshes deposited on or imbedded in the ICM; or (c) catalytically active nanostructured composite elements embedded in the surface of the ICM.
Nanostructured composite articles have been disclosed. See, for example, U. S. Patent Nos. 4,812,352, 5,039,561, 5,176,786, 5,336,558, 5,338,430, and 5,238,729. U.S. Patent No. 5,338,430 discloses that nanostructured electrodes embedded in solid polymer electrolyte offer superior properties over conventional electrodes employing metal fines or carbon supported metal catalysts, including:
protection of the embedded electrode material, more efficient use of the electrode material, and enhanced catalytic activity.
Summary of the Invention Briefly, this invention provides a method of making a membrane electrode assembly that comprises a composite membrane, which includes both a porous membrane and an ion conducting electrolyte, by partially filling a porous membrane with an ion conducting electrolyte to form a partially filled membrane SUBSTITUTE SHEET (RULE 26) WO 99/19930 PC1'/US98/18654 and then compressing together the partially filled membrane and electrode particles so as to remove void volume from the partially f lied membrane and embed the electrode particles in the partially filled membrane. The membrane electrode assembly of this invention is suitable for use in electrochemical devices, including S proton exchange membrane fuel cells, electrolyzers, chior-alkali separation membranes, sensors and the like.
In another aspect, the present invention provides a composite membrane including a polymerization product comprising one or more monomers having the formula CHZ~H-Ar-SOZ N--SOZ(C,a."F,+ZJ, wherein n is 0-11, preferably 0-3, and most preferably 0, and wherein Ar is any substituted or unsubstituted aryl group, preferably of molecular weight less than 400 and most preferably a divalent phenyl group.
In a further aspect, the invention provides a fuel cell assembly comprising at least one membrane electrode assembly disclosed above.
In yet another aspect, the invention provides an electrochemical device comprising at least one MEA disclosed above.
In the method of the present invention, a porous membrane is partially filled with an ion conducting electrolyte to form a partially filled membrane.
The partially filled membrane is then pressed with electrode particles so as to embed the electrode particles in the partially filled membrane. It was found that this pressing step also removed void volume remaining after the filling step, and therefore resulted in a thinner and less porous composite membrane than previously contemplated. In a preferred embodiment, the present invention provides a method for forming a membrane electrode assembly that comprises embedded electrode particles, which may be nanostructured catalyst particles, together with a composite membrane.
Furthermore, under certain circumstances it was observed that, not only was the void space of the porous membrane filled, but the porous structure itself was obliterated. Under a scanning electron microscope the resulting membrane appeared uniform, even at a magnification of 10,000x. Thus, in another preferred embodiment, the present invention provides a method for forming a membrane electrode assembly that comprises a composite membrane which has acquired a SUBSTITUTE SHEET (RULE 2G) WO 99/19930 PCT/US98/18b54 uniform, undifferentiated structure, that is, wherein the porous structure of the initially porous membrane is obliterated.
In addition, resulting MEA's were shown to function well in electrochemical cells.
In this application:
"composite membrane" means a membrane composed of more than one material and including both a porous membrane material and an ion conducting electrolyte material;
"membrane electrode assembly" means a structure comprising a membrane that includes an electrolyte and at least one but preferably two or more electrodes adj oining the membrane;
"substituted" means, for a chemical species, having a conventional substituent that does not interfere with the desired product;
"nanostructured element" means an acicular, discrete, sub-microscopic structure comprising an electrically conductive material on at least a portion of its surface;
"acicular" means having a ratio of length to average cross-sectional width of greater than or equal to 3;
"discrete" refers to distinct elements, having a separate identity, but does not preclude elements from being in contact with one another;
"sub-microscopic" means having at least one dimension smaller than about a micrometer;
"Gurley number" means a measure of the resistance to gas flow of a membrane, expressed as the time necessary for a given volume of gas to pass through a standard area of the membrane under standard conditions, as specified in ASTM D726-58, Method A, described fiu~ther below; and "pore size" means a measure of size of the largest pore in a membrane as specified in ASTM F-316-80, described further below.
It is an advantage of the present invention to provide a method of'making a strong, thin, and more gas impervious membrane electrode for use in membrane electrode assemblies. In particular, it is an advantage of the present invention to provide a method of making a membrane electrode comprising a thinner and more SUBSTITUTE SHEET (RULE 26) WO 99/19930 PCT/US98/18654 _ completely filled composite membrane with nanostructured electrodes. In addition, it is an advantage of the present invention to pmvide a method of making a membrane electrode comprising a thin and non-porous composite membrane lacking any visible porous structure and having nanostructured electrodes.
Brief Description of the Drawings Fig. 1 is a graph of the average mass of three membrane samples after each of repeated steps of dipping in electrolyte solution and drying, according to the present invention.
Fig. 2 is a graph of the average mass of three membrane samples after each of repeated steps of dipping in electrolyte solution and drying, according to the present invention.
Fig. 3 is a scanning electron micrograph taken at 2,OOOX magnification of the surface of a membrane useful in the method of the present invention.
Fig. 4 is a scanning electron micrograph taken at 1,OOOX magnification of a cross-section of an MEA of the present invention.
Fig. S is a scanning electron micrograph taken at S,OOOX magnification of a cross-section of an MEA of the present invention.
Fig. 6 is a scanning electron micrograph taken at 4,OOOX magnification of a cross-section of a comparative MEA omitting electrolyte.
Fig. 7 is a graph of a polarization curve of voltage versus current density produced by two fuel cell assemblies of the present invention.
Fig. 8 is a graph of a polarization curve of voltage versus current density produced by a fuel cell assembly of the present invention.
Fig. 9 is a scanning electron micrograph taken at 1,OOOX magnification of the surface of a membrane useful in the method of the present invention.
Fig. 10 is a scanning electron micrograph taken at 1,OOOX magnification of a cross-section of an MEA of the present invention.
Fig. 11 is a scanning electron micrograph taken at 10,000X magnification of a cross-section of an MEA of the present invention.
Fig. 12 is a scanning electron micrograph taken at 2,520X magnification of a cross-section of an MEA of the present invention.
SUBSTITUTE SHEET (RULE 26) WO 99/19930 PCTNS98/18654 _ Detailed Description of tl<e Preferred Embo invents In the method of the present invention, a porous membrane is partially filled with an ion conducting electrolyte to form a partially filled composite membrane. The partially filled membrane is then compressed with electrode particles so as to fiuther exclude void volume from the membrane and embed the electrode particles in the membrane.
Any suitable porous membrane may be used. Porous membranes useful as reinforcing membranes of the invention can be of any construction having sufficient porosity to allow at least one solidifiable ICM to be infitsed or imbibed thereinto and having suffcient strength to withstand operating conditions in an electrochemical cell. Preferably, porous membranes useful in the invention comprise a polymer that is inert to conditions in the cell, such as a polyolefin, or a halogenated, preferably fluorinated, polyvinyl) resin. Expanded PTFE membranes may be used, such as PoreflonTM, produced by Sumitomo Electric Industries, Inc., Tokyo, Japan, and TetratexTM. produced by Tetratec, Inc., Feasterville, PA.
More preferably, porous membranes of the invention comprise microporous films prepared by thermally-induced phase separation (TIPS) methods, as described in, e.g.', U. S. Patent Nos. 4,539,256, 4,726,989, 4,867,881, 5,120,594 and 5,260,360. TIPS films exhibit a multiplicity of spaced, randomly dispersed, equiaxed, nonuniform shaped particles of a thermoplastic polymer in the form of a film, membrane, or sheet material. Micropores defined by the particles preferably are of sufficient size to allow ICMs to be incorporated therein. Figs. 3 and 9 are scanning electron micrographs at 2000x and 1000x magnification, respectively, of the porous surfaces of two such TIPS membranes.
Polymers suitable for preparing films by the TIPS process include thermoplastic polymers, thermosensitive polymers, and mixtures of these polymers, so long as the mixed polymers are compatible. Thermosensitive polymers such as ultrahigh molecular weight polyethylene (UI~VIWPE) cannot be melt-processed directly but can be melt-processed in the presence of a diluent that lowers the viscosity thereof sufficiently for melt processing.
_7_ SUBSTITUTE SHEET (RULE 26) Suitable polymers include, for example, crystallizable vinyl polymers, condensation polymers, and oxidation polymers. Representative crystallizable vinyl polymers include, for example, high- and low-density polyethylene, polypropylene, polybutadiene, polyacrylates such as poly(methyl methacrylate), fluorine-containing polymers such as poly(vinylidene fluoride), and the like.
Useful condensation polymers include, for example, polyesters, such as polyethylene terephthalate) and poly(butylene terephthalate), polyamides, including many members of the NylonTM family, polycarbonates, and polysulfones.
Useful oxidation polymers include, for example, poly(phenylene oxide) and poly(ether ketone). Blends of polymers and copolymers may also be usefixl in the invention. Preferred polymers for use as reinforcing membranes of the invention include crystallizable polymers, such as polyolefins and fluorine-containing polymers, because of their resistance to hydrolysis and oxidation. Preferred polyolefins include high density polyethylene, polypropylene, ethylene-propylene copolymers, and poly(vinylidene fluoride).
Any suitable ion exchange electrolyte may be used. The electrolytes are preferably solids or gels under the operating conditions of the electrochemical cell.
Electrolytes useful in the present invention can include ion conductive materials, such as polymer electrolytes, and ion-exchange resins. The electrolytes are preferably proton conducting ionomers suitable for use in proton exchange membrane fuel cells.
Ion conductive materials useful in the invention can be complexes of an alkalai metal or alkalai earth metal salt or a protonic acid with one or more polar polymers such as a polyether, polyester, or polyimide, or complexes of an alkalai metal or alkalai earth metal salt or a protonic acid with a network or crosslinked polymer containing the above polar polymer as a segment. Useful polyethers include: polyoxyallcylenes, such as polyethylene glycol, polyethylene glycol monoether, polyethylene glycol diether, polypropylene glycol, polypropylene glycol monoether, and polypropylene glycol diether; copolymers of these polyethers, such as poly(oxyethylene-co-oxypropylene) glycol, poly(oxyethylene-co-oxypropylene) glycol monoether, and poly(oxyethylene-co-oxypropylene) glycol diether; condensation products of ethylenediamine with the above _g_ SUBSTITUTE SHEET (RULE 26) WO 99/19930 . PGTNS98/18654 _ polyoxyalkylenes; esters, such as phosphoric acid esters, aliphatic carboxylic acid esters or aromatic carboxylic acid esters of the above polyoxyalkylenes.
Copolymers of, e.g., polyethylene glycol with dialky siloxanes, polyethylene glycol with malefic anhydride, or polyethylene glycol monoethyl ether with methacrylic acid are known in the art to exhibit sufficient ionic conductivity to be useful in an ICM of the invention. Useful complex-forming reagents can include alkalai metal salts, alkalai metal earth salts, and protonic acids and protonic acid salts. Counterions useful in the above salts can be halogen ion, perchloric ion, thiocyanate ion, trifluoromethane sulfonic ion, borofluoric ion, and the like.
Representative examples of such salts include, but are not limited to, lithium fluoride, sodium iodide, lithium iodide, lithium perchlorate, sodium thiocyanate, lithium trifluoromethane sulfonate, lithium borofluoride, lithium hexafluorophosphate, phosphoric acid, sulfuric acid, trifluoromethane sulfonic acid, tetrafluoroethylene sulfonic acid, hexafluorobutane sulfonic acid, and the like.
Ion-exchange resins useful as electrolytes in the present invention include hydrocarbon- and fluorocarbon-type resins. Hydrocarbon-type ion-exchange resins can include phenolic or sulfonic acid-type resins; condensation resins such as phenol-formaldehyde, polystyrene, styrene-divinyl benzene copolymers, styrene-butadiene copolymers, styrene-divinylbenzene-vinylchloride terpolymers, and the like, that are imbued with cation-exchange ability by sulfonation, or are imbued with anion-exchange ability by chloromethylation followed by conversion to the corresponding quaternary amine.
Fluorocarbon-type ion-exchange resins can include hydrates of a tetrafluoroethylene-perfluorosulfonyl ethoxyvinyl ether or tetrafluoroethylene-hydroxylated (perfluoro vinyl ether) copolymers. When oxidation and/or acid resistance is desirable, for instance, at the cathode of a fuel cell, fluorocarbon-type resins having sulfonic, carboxylic and/or phosphoric acid functionality are preferred. Fluorocarbon-type resins typically exhibit excellent resistance to oxidation by halogen, strong acids and bases, and can be preferable for composite electrolyte membranes useful in the invention. One family of fluorocarbon-type resins having sulfonic acid group functionality is the NafionTM resins (DuPont Chemicals, Wilmington, DE, available from ElectroChem, Inc., Woburn, MA, and SUBSTITUTE SHEET (RULE 26) WO 99/19930 PCTNS98/18654 _ Aldrich Chemical Co., Inc., Milwaukee, WI). Other fluorocarbon-type ion-exchange resins that can be useful in the invention comprise (copolymers of olefins containing aryl perfluoroalkyl sulfonylimide cation-exchange groups, having the general formula (I): CH2 CH-Ar-SOZ-N--SOZ(C""F3+z~, wherein n is 0-11, preferably 0-3, and most preferably 0, and wherein Ar is any substituted or unsubstituted aryl group, preferably monocyclic and most preferably a divalent phenyl group, referred to as phenyl herein. Ar may include any substituted or unsubstituted aromatic moieties, including benzene, naphthalene, anthracene, phenanthrene; indene, fluorene, cyclopentadiene and pyrene, wherein the moieties are preferably molecular weight 400 or less and more preferably 100 or less.
One such resin is p-STSI, an ion conductive material derived from free radical polymerization of styrenyl trifluoromethyl sulfonylimide (STSI) having the formula (II): styrenyl-SOZN--SOZCF3. This embodiment, wherein n~ and Ar is unsubsdtuted phenyl, is the most preferred embodiment according to formula I.
Preferably the electrolyte is a polymeric resin. In one embodiment the most preferred electrolyte is NafionTM. In another embodiment, wherein the porous structure of the composite membrane is obliterated, the preferred electrolytes are polyolefins containing aryl perfluoroalkyl sulfonylimide groups according to formula (I), above, and the most preferred electrolyte is p-STSI.
Any suitable procedure may be used to partially fill the porous membrane with the electrolyte. In the "multiple dipping" approach, illustrated in the Examples, the porous membrane is immersed in relatively low concentration electrolyte solution for short times, dried, and the process repeated multiple times.
The dipping may be repeated until the weight of the membrane approaches a steady state as no further electrolyte is incorporated. Preferably, the dipping is repeated until at least this point, but may be terminated before this point. Any concentration of electrolyte solution may be used, however, very low concentrations may require increased dipping repetitions or may result in lower loading of electrolyte. A
solution of about 5 wt% is preferred. The membrane may be dried by any means, preferably at elevated temperature such as in an air oven. Drying temperature is preferably between 40° C and b0° C. Without being limited to any one theory, it is proposed that the adsorption of the electrolyte polymer onto the porous matrix SUBSTITUTE SHEET (RULE 26) fibrils occurs primarily as the concentration of the solution increases during the solvent evaporation stage, so increasing the number of such events will enhance filling.
In the "long soak" approach, illustrated in the Examples, the porous membrane is immersed in the electrolyte solution for prolonged periods, preferably exceeding 20 minutes, then dried. Any concentration of electrolyte solution may be used, however, very low concentrations may require increased soaking time or may result in lower loading of electrolyte. A solution of about 5 wt% is preferred.
The membrane may be dried by any means, preferably at elevated temperature such as in an air oven. Drying temperature is preferably between 40° C
and 60° C.
In the "vacuum" approach, illustrated in the Examples, sub-atmospheric air pressure is applied to the underside of the porous membrane by any suitable means to draw an electrolyte solution applied to its top through the membrane and the membrane is then dried. A Venturi pump may be used to generate sub-1 S atmospheric air pressure. The vacuum is applied for as long as necessary to draw enough solution into the membrane so as to partially fill the membrane, preferably between 1 second and 10 minutes. Any concentration of electrolyte solution may be used, however, higher concentrations appear to result in increased loading of electrolyte, and higher viscosity requires increased time to load the solution into the membrane. A solution of greater than about 10 wt% is preferred, and a solution of about 20 wt% is most preferred. The membrane may be dried by any means, preferably at elevated temperature such as in an air oven. Drying temperature is preferably between 40° C and 60° C.
In the "hydraulic press" approach, illustrated in the Examples, a room temperature mechanical press is used to force high concentration viscous electrolyte solutions through the porous membrane. Preferably, the membrane material is sandwiched between impermeable film layers having mask holes cut in the area to be filled with electrolyte. The mask layers may be prepared firm polyethylene terephthalate (PET) film, preferably about 100 micrometers thick.
The electrolyte solution is added dropwise to the membrane surface. Additional layers or shims may be added before the membrane is placed in the press. The pressure used may be up to 2 tons/cmz, preferably between 0.1-I .0 tons/cm~, and SUBSTITUTE SHEET (RULE 26) more preferably 0.4-0.6 tons/cmz. Any means of applying pressure may be employed, including nip rollers and flat bed presses. A continuous pmcess is preferred. Force is applied for as long as necessary to partially fill the membrane, typically between 1 second and 10 minutes. After pressing, any excess solution is wiped off the surface of the membrane and the membrane is dried. The membrane may be dried by any means, preferably at elevated temperature such as in an air oven. Drying temperature is preferably between 40° C and 60° C.
In the "evaporation" approach the porous membrane is placed over a thin volume of solution, causing the solution to partially fill the membrane finm the underside by capillarity. The solvent is allowed to evaporate through the top surface of the membrane. The process may be carried out at any temperature at which the solvent will evaporate, preferably room temperature or higher.
Preferably, the hydraulic press, vacuum or multiple dipping method is used.
Most preferably, the hydraulic press method is used.
The amount of electrolyte solution used in the filling process should be sufficient to achieve the degree of filling desired but is preferably in excess of that which would theoretically fill the membrane. The amount of electrolyte imbibed in the pores or adsorbed on the fibrils of the membrane after the partial filling should be sufficient to fill between 10% and 90% of the available pore volume.
Preferably, more than 15% of the available pore volume is filled. Most preferably, between 35% and 65% of the available pore volume is filled. The electrolyte may be present as a coating on the structural fibrils of the porous membrane or it may wet out the membrane, filling the entire cross section of some pores. The increase in density of the membrane after partial filling should be at least 0.01 g/cm' but is preferably at least 0.1 g/cm' but less than 1.2 g/cm3.
Any suitable electrode particles may be used. At least a portion of the surface of suitable electrode particles is composed of a catalytic material.
Preferably, nanostructured elements are used, as described below. However, other electrode particles may be used, including metal fines or metal-coated support particles such as carbon particles. The catalytic material should be appropriate to the intended use of the MEA. Preferably the catalytic material is a Group VII
metal or an alloy thereof and most preferably Pt or an alloy thereof.

SU8STlTUTE SHEET (RULE 26) Nanostructured elements suitable for use in the present invention may comprise metal-coated whiskers of organic pigment, most preferably C.I.
PIGMENT RED 149 (perylene red). The crystalline whiskers have substantially uniform but not identical cross-sections, and high length-to-width ratios. The nanostructured whiskers are conformally coated with materials suitable for catalysis, and which endow the whiskers with a fine nanoscopic surface structure capable of acting as multiple catalytic sites.
U.S. Patent Nos. 4,812,352 and 5,039,561 disclose a preferred method for making an organic-based microstructured layer of whiskers, suitable for coating with a nanoscopic surface layer to generate nanostructured whiskers suitable for use in the present invention. As disclosed therein, a method for making a microstructured layer of whiskers comprises the steps of i) depositing or condensing a vapor of an organic material as a thin, continuous or discontinuous layer onto a substrate; and ii) annealing the deposited organic layer in a vacuum for a time and at a temperature sufficient to induce a physical change in the deposited organic layer to form a microstructured layer comprising a dense array of discrete microstructures or whiskers but insufficient to cause the organic layer to evaporate or sublimate.
A layer of whiskers can be deposited on a substrate of any desired size by a totally dry process, and conveniently and rapidly patterned using, for example, high resolution (dry) laser ablation means.
Orientation of the whiskers is generally uniform in relation to the surface of the substrate. The whiskers are usually oriented normal to the original substrate surface, the surface normal direction being defined as that direction of the line perpendicular to an imaginary plane lying tangent to the local substrate surface at the point of contact of the base of the whisker with the substrate surface. The surface normal direction is seen to follow the contours of the surface of the substrate. The major axes of the whiskers can be parallel or nonparallel to each other.
Alternatively, the whiskers can be nonuniform in shape, size, and orientation.
For example, the tops of the whiskers can be bent, curled, or curved, or the whiskers can be bent, curled, or curved over their entire length.

SUBSTITUTE SHEET (RULE 26) Preferably, the whiskers are of uniform length and shape, and have uniform cross-sectional dimensions along their major axes. The preferred length of each whisker is less than about SO micrometers. More preferably, the length of each whisker is in the range from about 0.1 to 5 micrometers, most preferably 0.1 to 3 micrometers. Within any whisker layer it is preferable that the whiskers be of uniform length. Preferably, the average cross-sectional dimension of each whisker is less than about 1 micrometer, more preferably 0.01 to 0.5 micrometer. Most preferably, the average cross-sectional dimension of each whisker is in the range from 0.03 to 0.3 micrometer.
Preferably, the whiskers have an areal number density in the range from about 10' to about 10" whiskers per square centimeter. More preferably, the whiskers have an areal density in the range from about 108 to about 10'° whiskers per square centimeter.
The whiskers can have a variety of orientations and straight and curved shapes. Any one layer can comprise a combination of orientations and shapes.
The whiskers have an aspect ratio (i.e., a length to diameter ratio) preferably in the range of from about 3:1 to about 100:1.
Materials useful as a substrate include those which maintain their integrity at the temperature and vacuum imposed upon them during the vapor deposition and annealing steps. The substrate can be flexible or rigid, planar or non-planar, convex, concave, textured, or combinations thereof. Preferred substrate materials include organic materials and inorganic materials (including, for example, glasses, ceramics, metals, and semiconductors). The preferred inorganic substrate material is glass or metal. The preferred organic substrate material is a polyirnide.
Representative organic substrates include those that are stable at the annealing temperature, for example, polymers such as polyimide film (commercially available, for example, under the trade designation "KAPTON" from DuPont Electronics, Wilmington, DE), high temperature stable polyimides, polyesters, polyamids, and polyaramids.
Metals useful as substrates include, for example, aluminum, cobalt, copper, molybdenum, nickel, platinum, tantalum, or combination thereof. Ceramics useful as a substrate material include, for example, metal or non-metal oxides such as alumina and silica.
A useful inorganic nonmetal is silicon.

SUBSTITUTE SHEET (RULE 26) The organic material from which the whiskers can be formed may be coated onto the substrate using techniques known in the art for applying a layer of an organic material onto a substrate, including, for example, vapor phase deposition (e.g., vacuum evaporation, sublimation, and chemical vapor deposition), and solution coating or dispersion coating (e.g., dip coating, spray coating, spin coating, blade or knife coating, bar coating, roll coating, and pour coating (i.e., pouring a liquid onto a surface and allowing the liquid to flow over the surface)). Preferably, the organic layer is applied by physical vacuum vapor deposition (i.e., sublimation of the organic material under an applied vacuum).
Useful organic materials for producing whiskers by, for example, coating followed by plasma etching, can include for example, polymers and prepolymers thereof (e.g., thermoplastic polymers such as, for example, alkyds, melamines, urea formaldehydes, diallyl phthalates, epoxies, phenolics, polyesters, and silicones;
thermoset polymers, such as acrylonitrile-butadiene-styrenes, acetals, acrylics, cellulosics, chlorinated polyethers, ethylene-vinyl acetates, fluorocarbons, ionomers, nylons, parylenes, phenoxies, polyallomers, polyethylenes, polypropylenes, polyamide-imides, polyimides, polycarbonates, polyesters, polyphenylene oxides, polystyrenes, polysulfones, and vinyls); and organometallics (e.g., bis(r~s-cyclopentadienyl)iron (11), iron pentacarbonyl, ruthenium pentacarbonyl, osmium pentacarbonyl, chromium hexacarbonyl, molybdenum hexacarbonyl, tungsten hexacarbonyl, and tris(triphenylphosphine) rhodium chloride).
Preferably, the chemical composition of the organic-based whisker layer will be the same as that of the starting organic material. Preferred organic materials useful in preparing the whisker layer include, for example, planar molecules comprising chains or rings over which ~-electron density is extensively delocalized.
These organic materials generally crystallize in a herringbone configuration.
Preferred organic materials can be broadly classified as polynuclear aromatic hydrocarbons and heterocyclic aromatic compounds.
Polynuclear aromatic hydrocarbons are described in Morrison and Boyd, Organic Chemistry, Third Edition, Allyn and Bacon, Inc. (Boston: 1974), Chapter 30. Heterocyclic aromatic compounds are described in Morrison and Boyd, supra, Chapter 31.

SUBSTITUTE SHEET (RULE 26) Preferred polynuclear aromatic hydrocarbons, which are commercially available, include, for example, naphthalenes, phenanthrenes, perylenes, anthracenes, coronenes, and pyrenes. A preferred polynuclear aromatic hydrocarbon is N,N'-di(3,5-xylyl)perylene-3,4,9,10 bis(dicarboximide) (commercially available under the trade designation "C. I. PIGMENT RED 149" firm American Hoechst Corp. of Somerset, N~, herein designated "perylene red."
Prefen~ed heterocyclic aromatic compounds, which are commercially available, include, for example, phthalocyanines, porphyries, carbazoles, purines, and pterins. Representative examples of heterocyclic aromatic compounds include, for example, metal-fi~ee phthalocyanine (e.g., dihydrogen phthalocyanine) and its metal complexes (e.g. copper phthalocyanine).
The organic materials preferably are capable of forming a continuous layer when deposited onto a substrate. Preferably, the thickness of this continuous layer is in the range from 1 nanometer to about one thousand nanometers.
Orientation of the whiskers can be affected by the substrate temperature, the deposition rate, and angle of incidence during deposition of the organic layer. If the temperature of the substrate during deposition of the organic material is sufficiently high (i.e., above a critical substrate temperature which has been associated in the art with a value one-third the boiling point (K) of the organic material), the deposited organic material will form randomly oriented whiskers either as deposited or when subsequently annealed. If the temperature of the substrate during deposition is relatively low (i.e., below the critical substrate temperature), the deposited organic material tends to form uniformly oriented whiskers when annealed. For example, if uniformly oriented whiskers comprising perylene red are desired, the temperature of the substrate during the deposition of the perylene red is preferably about 0 to about 30°C. Certain subsequent conformal coating processes, such as DC
magnetron sputtering and cathodic arc vacuum processes, can produce curvilinear whiskers.
There can be an optimum maximum annealing temperature for different film thicknesses in order to filly convert the deposited layer to whiskers. When fully converted, the major dimension of each whisker is directly proportional to the thickness of the initially deposited organic layer. Since the whiskers are discrete, are separated by distances on the order of their cross-sectional dimensions, and SUBSTITUTE SHEET (RULE 26) preferably have uniform cross-s~tional dimensions, and all the original organic film material is converted to whiskers, conservation of mass implies that the lengths of the whiskers will be proportional to the thickness of the layer initially deposited. Due to this relationship of the original organic layer thickness to the lengths of the whiskers, and the independence of cross-sectional dimensions from length, the lengths and aspect ratios of the whiskers can be varied independently of their cross-sectional dimensions and areal densities. For example, it has been found that the length of whiskers are approximately 10-15 times the thickness of the vapor deposited perylene red layer, when the thickness ranges from about 0.05 to about 0.2 micrometer. The surface area of the whisker layer (i.e., the sum of the surface areas of the individual whiskers) is much greater than that of the organic layer initially deposited on the substrate. Preferably, thickness of the initially deposited layer is in the range from about 0.03 to about 0.25 micrometer.
Each individual whisker can be monocrystalline or polycrystalline, rather than amorphous. The whisker layer can have highly anisotropic properties due to the crystalline nature and uniform orientation of the whiskers.
If a discontinuous distribution of whiskers is desired, masks may be used in the organic layer deposition step to selectively coat specific areas or regions of the substrate. Other techniques known in the art for selectively depositing an organic layer on specific areas or regions of a substrate may also be useful.
In the annealing step, the substrate having an organic layer coated thereon is heated in a vacuum for a time and at a temperature sufficient for the coated organic layer to undergo a physical change, wherein the organic layer grows to form a whisker layer comprising a dense array of discrete, oriented monocrystalline or polycrystalline whiskers. Uniform orientation of the whiskers is an inherent consequence of the annealing process when the substrate temperature during deposition is sufficiently low. Exposure of the coated substrate to the atmosphere prior to the annealing step is not observed to be detrimental to subsequent whisker formation.
If, for example, the coated organic material is perylene red or copper phthalocyanine, annealing is preferably done in a vacuum (i.e., less than about 0.13 Pa) at a temperature in the range from about 160 to about 270°C. The annealing time SUBSTITUTE SHEET (RULE 26) necessary to convert the original organic layer to the whisker layer is dependent on the annealing temperature. Typically, an annealing time in the range from about 10 minutes to about 6 hours is sufficient. Preferably the annealing time is in the range from about 20 minutes to about 4 hours. Further, for perylene red, the optimum annealing temperature to convert all of the original organic layer to a whisker layer, but not sublime it away, is observed to vary with the deposited layer thickness.
Typically, for original organic layer thicknesses of 0.05 to 0.15 micrometer, the temperature is in the range of 245 to 270°C.
The time interval between the vapor deposition step and the annealing step can vary from several minutes to several months, with no significant adverse efl'ect, provided the coated composite is stored in a covered container to minimize contamination (e.g., dust). As the whiskers grow, the organic infrared band intensities change and the laser specular reflectivity drops, allowing the conversion to be carefully monitored, for example, in situ by surface infrared spectroscopy.
After the whiskers have grown to the desired dimensions, the resulting layered structure, which comprises the substrate and the whiskers, is allowed to cool before being brought to atmospheric pressure.
If a patterned distribution of whiskers is desired, whiskers may be selectively removed firm the substrate, for example, by mechanical means, vacuum process means, chemical means, gas pressure or fluid means, radiation means, and combinations thereof. Useful mechanical means include, for example, scraping whiskers offthe substrate with a sharp instrument (e.g., with a razor blade), and encapsulating with a polymer followed by delamination. Useful radiation means include laser or light ablation. Such ablation can result in a patterned electrode.
Useful chenucal means include, for example, acid etching selected areas or regions of the whisker layer. Useful vacuum means include, for example, ion sputtering and reactive ion etching. Useful air pressure means include, for example, blowing the whiskers off the substrate with a gas (e.g., air) or fluid stream.
Combinations of the above are also possible, such as use of photoresists and photolithography.
The whiskers can be extensions of the substrate and of the same material as the substrate by, e.g., vapor depositing a discontinuous metal microisland mask onto the surface of a polymer, then plasma or reactive ion etching away the SUBSTITUTE SHEET (RULE 26) WO 99/19930 PCTNS98/18654 _ polymer material not masked by the metal microislands, to leave polymer substrate posts protruding from the surface, so long as they are transferable to the ICM.
Other methods for making microstructured layers of whiskers or nanostructured elements are known in the art. For example, methods for making organic microstructured layers of whiskers are disclosed in Materials Science and Engineering, AI58 (1992), pp. 1-6; J_. Vac. Sci. Technol - ~, (4), July/August, 1987, pp. 1914-16; J. Vac Sci Technol A, 6_, (3), May/August, 1988, pp. 1907-11;
Thin Solid Films, 186, 1990, pp. 327-47; J. Mat. ci., 25 1990, pp. 5257-68; R
i 1 Ouenched Metals. Proc. of the Fifth Int. Conf: on Rapidly Quenched Metals, Wurzburg, Germany (Sept. 3-7, 1984), S. Steeb et al., eds., Elsevier Science Publishers B.V., New York, (1985), pp. 1117-24; Photo. Sci. and ne 24 (4), July/August, 1980, pp. 211-16; and U.S. Patent Nos. 4,568,598 and 4,340,276.
Methods for making inorganic-based microstructured layers of whiskers are disclosed, for example, in J. Vac. Sci. Tech. A, _l, (3), July/Sept., 1983, pp. 1398-1 S 1402 and U.S. Patent No. 3,969,545; U.S. Patent Nos. 4,252,865, 4,396,643, 4,148,294, 4,252,843, 4,155,781, 4,209,008, and 5,138,220.
Usefizl inorganic materials for producing whiskers include, for example, carbon, diamond-like carbon, ceramics (e.g., metal or non-metal oxides such as alumina, silica, iron oxide, and copper oxide; metal or non-metal nitrides such as silicon nitride and titanium nitride; and metal or non-metal carbides such as silicon carbide; metal or non-metal borides such as titanium boride); metal or non-metal sulfides such as cadmium sulfide and zinc sulfide; metal silicides such as magnesium silicide, calcium silicide, and iron silicide; metals (e.g., noble metals such as gold, silver, platinum, osmium, iridium, palladium, ruthenium, rhodium, and combinations thereof; transition metals such as scandium, vanadium, chromium, manganese, cobalt, nickel, copper, zirconium, and combinations thereof; low melting metals such as bismuth, lead, indium, antimony, tin, zinc, and aluminum; refractory metals such as tungsten, rhenium, tantalum, molybdenum, and combinations thereof); and semiconductor materials (e.g., diamond, germanium, selenium, arsenic, silicon, tellurium, gallium arsenide, gallium antimonide, gallium phosphide, aluminum antimonide, indium antimonide, indium tin oxide, zinc antimonide, indium phosphide, aluminum gallium arsenide, zinc telluride, and combinations thereof).

SUBSTITUTE SHEET (RULE 26) The whiskers of the preferred embodiment can be made to have random orientations by control of the substrate temperature during the deposition of the initial PR149 layer, as described above. They can also be made to have curvilinear shapes by conditions of the confonnal coating process. As discusses in FIG. 6 of L.
Aleksandrov, "GROWTH OF CRYSTALLINE SEMICONDUCTOR MATERIALS
ON CRYSTAL SURFACES," Chapter 1, Elsevier, New York, 1984, the energies of the arriving atoms applied by different coating methods, e.g., thermal evaporation deposition, ion deposition, sputtering and implantation, can range over S
orders of magnitude.
It is within the scope of the present invention to modify the methods for making a microstructured layer of whiskers to make a discontinuous distribution of whiskers.
Preferably, the one or more layers of confonnal coating material, if applied, serve as a functional layer imparting desirable catalytic properties, as well as electrical conductivity and mechanical properties (e.g., strengthens and/or protects the whiskers comprising the whisker layer), and low vapor pressure properties.
The conformal coating material preferably can be an inorganic material or it can be an organic material including a polymeric material. Useful inorganic conformal coating materials include, for example, those described above in the description of the whiskers. Useful organic materials include, for example, conductive polymers (e.g., polyacetylene), polymers derived from poly-p-xylylene, and materials capable of forming self assembled layers.
The preferred thickness of the conformal coating is typically in the range from about 0.2 to about 50 nm. The conformal coating may be deposited onto the whisker layer using conventional techniques, including, for example, those disclosed in U.S. Patent Nos. 4,812,352 and 5,039,561. Any method that avoids disturbance of the whiskers by mechanical forces can be used to deposit the conformal coating.
Suitable methods include, for example, vapor phase deposition (e.g., vacuum evaporation, sputter coating, and chemical vapor deposition) solution coating or dispersion coating (e.g., dip coating, spray coating, spin coating, pour coating (i.e., pouring a liquid over a surface and allowing the liquid to flow over the whisker layer, followed by solvent removal)), immersion coating (i.e., immersing the whisker layer SUBSTITUTE SHEET (RULE 26) in a solution for a time sufficient to allow the layer to adsorb molecules from the solution, or colloidals or other particles from a dispersion), electroplating and electrodeless plating. More preferably, the conformal coating is deposited by vapor phase deposition methods, such as, for example, ion sputter deposition, cathodic arc deposition, vapor condensation, vacuum sublimation, physical vapor transport, chemical vapor transport, and metalorganic chemical vapor deposition.
Preferably, the conformal coating material is a catalytic metal or metal alloy.
For the deposition of a patterned confonnal coating, the deposition techniques are modified as is known in the art to produce such discontinuous coatings. Known modifications include, for example, use of masks, shutters, directed ion beams, and deposition source beams.
The electrode particles can be embedded in the partially filled membrane by applying heat and mechanical pressure and subsequently removing the original substrate supporting the particles. Any suitable source of pressure may be employed. A hydraulic press is preferably employed. Alternately, pressure may be applied by one or a series of nip rollers. This process is also adaptable to a continuous process, using either a flat bed press in a repeating operation or rollers in a continuing operation. Shims, spacers, and other intermediate mechanical devices may be employed. The electrode particles are preferably supported on a substrate which is applied to the membrane surface, such that the particles contact the membrane surface. The substrate is removed after pressing, leaving the electrode particles embedded in the membrane. Alternately, the electrode particles may be applied directly to the membrane surface, free of any substrate and without inclusion of any additional ionomer, and then pressed into the surface. In one embodiment, a partially filled membrane disk may be placed between two sheets of polyimide-supported nanostructured films of nanostructured elements which are placed against the partially filled membrane. Additional layers of uncoated polyimide and PTFE sheets are fiuther layered on either side of the sandwich for uniform distribution of pressure, and finally a pair of stainless steel shims is placed outside of this assembly.
The pressure, temperature and duration of pressing may be any combination sufficient to exclude void volume from the membrane and embed the electrode SUBSTITUTE SHEET (RULE 2fi) WO 99/19930 PCT/US98/18654 .
particles in the membrane. The optimum conditions depend on the properties of the porous membrane. Preferably, a pressure of between 0.05 and 10 tons/cm2 is used and more preferably a pressure of between 0.1 and 1.0 ton/cm2. Most preferably, a pressure of between 0.10 and 0.20 ton/cmz is used. Preferably the press temperature is between 20° C and 300° C, and most preferably between 80° C
and 250° C. The pressing time is preferably greater than one second and most preferably about one minute. After loading into the press, the MEA components may be allowed to equilibrate to the press temperature, at low or no pressure, prior to pressing. Alternately, the MEA components may be preheated in an oven or other apparatus adapted for the purpose. Preferably the MEA components are preheated for 1-10 minutes before pressing. The MEA may be cooled before or after removal from the press. The platens of the press may be water cooled or cooled by any other suitable means. Preferably, the MEA is cooled for 1-10 minutes while still under pressure in the press.
Fig. 4 is an SEM micrograph at 1000X of a cross-section of an MEA made by the method of the present invention.
In one embodiment, p-STSI is used as the electrolyte. In the resulting MEA, the porous structure of the composite membrane is apparently obliterated.
The ion conducting membrane portion of the resulting MEA appears to be a homogenous combination of the membrane material and the electrolyte. The membrane loses its original porous structure and, in particular, has no remaining membrane-crossing pores. In this embodiment, any method may be used to partially fill the membrane, as described above. Any pressing conditions, described above, may be used. Any porous membrane may be used, however, polypropylene membranes and TIPS membranes are preferred and polypropylene TIPS membranes are most preferred.
This invention is useful in electrochemical devices such as fuel cells, electrolyzers, batteries, or gas, vapor or liquid sensors, using membrane electrodes optimized for the immediate purpose.
Objects and advantages of this invention are further illustrated by the following examples, but the particular materials and amounts thereof recited in SUBSTITUTE SHEET (RULE 26) WO 99/19930 PCT/US98/18654 _ these examples, as well as other conditions and details, should not be construed to unduly limit this invention.
Ex s Examples 1-19, below, demonstrate partial filling of various porous polymer membranes with various ion conducting electrolytes by several different methods. Examples 20-25, following, demonstrate partial filling of the membranes followed by pressing of the partially filled membranes with electrode particles.
Materials used in the examples These porous membranes are used in the following examples:
TIPSTM membrane A is a polypropylene TIPSTM (Thermally Induced Phase Separation media), having 4.3 sec/50 cc Gurley, 0.84 micrometer (bubble point) pore size, about 70% void and 3.5 mil (89 microns) thickness. The membrane was prepared as follows: Polypropylene resin (DS SD45, Shell Chemicals Co., Houston, TX) having a melt flow index of 0.65 dg/min. (ASTM D1238, Condition I), was fed into the hopper of a 40 mm twin-screw extruder (Berstorff Corp., Charlotte, NC). Amoco White Mineral Oil #31 (AMOCO, Chicago, IL) having a viscosity of 60 centistokes (ASTM D445 at 40° C), was introduced into the extruder through an injection port at a rate to provide a composition of 31 %
by weight of polymer and 69 % by weight mineral oil. The composition also contained 0.24 % by weight dibenzylidene sorbital (Millad TM 3905, Milliken Chemical Corp., Spartanburg, NC) as a nucleating agent. The overall feed rate was 16.80 kg/hr. The polymer was heated to 266° C in the extruder to melt it and, after mixing with oil, the temperature was maintained at 166° C during extrusion. The melt was extruded through a 38.1 cm-side coat hanger slit die and cast onto a casting wheel maintained at 66° C. The cast film was extracted with dichlorotrifluoroethane (CHCIzCF,, available as VertrelTM 423, DuPont Chemical Co., Wilmington, DE) to remove mineral oil, then oriented 2.1 to 1 in the machine direction at 88° C and 2.8 to 1 in the cross-direction at 140°
C.
TIPSTM membrane B is a polypropylene TIPSTM, having 68 secs/50 cc Gurley, 0.1 micrometer pore size, 58% void and 29 micrometers (1.13 mil) SUBSTITUTE SHEET (RULE 26) thickness. The membrane was prepared as follows: Polypropylene resin (DS
SD45, Shell Chemicals Co., Houston, TX) having a melt flow index of 0.65 dg/min (ASTM D1238, Condition I), was fed into the hopper of a 40 mm twin-screw extruder (Berstorff Corp., Charlotte, NC). Amoco White Mineral Oil #31 (AMOCO, Chicago, IL) having a viscosity of 60 centistokes (ASTM D445 at 40°
C), was introduced into the extruder through an injection port at a rate to provide a composition of 55% by weight of the polymer and 45% by weight mineral oil. The composition also contained 0.28% dibenzylidine sorbital (MilladTM 3905, Milliken Chemical Corp., Spartanburg, NC) as a nucleating agent. The overall feed rate was 11.35 kglhr. The polymer was heated to 271° C in the extruder to melt and, after mixing with oil, the temperature was maintained at 177° C during the extrusion.
The melt was extruded through a 38.1 cm-wide coat hanger slit die and cast onto a casting wheel maintained at 60° C. The cast film was extracted with dichlorotrifluoroethane (CHC12CF3, available as VertrelTM 423, DuPont Chemical Co., Wilmington, DE) to remove mineral oil, then oriented 3.25 to lin the machine direction at 90° C and 1.5 to 1 in the cross-direction at 138°
C.
TIPSTM membrane C is a polyvinylidenedifluoride TIPSTM, having 366 secs/50 cc Gurley number, 0.07 micrometer pore size, 44% void volume and 69 micrometer (2.7 mil) thickness. The membrane was prepared as follows: Solef~'M
1010 polyvinylidenedifluoride (PVDF) resin (Solway America Inc., Houston, TX) was fed into the hopper of a 40 mm twin-screw extruder (Berstorff Corp., Charlotte, NC). Dibutyl phthalate (Aldrich Chemical Co., Inc., Milwaukee, WI) was introduced into the extruder through an injection port at a rate to provide a composition of 60% by weight of the polymer and 40% by weight dibutyl phthalate. The overall feed rate was 14.8 kg/hr. The melt was extruded at 204° C
through a 30.5 cm-wide coat hanger slit die and quenched in a water bath maintained at 28° C. The cast film was extracted with 1,1,1 trichloroethane {Aldrich) to remove dibutyl phthalate, then oriented 1.3 to 1 in the machine direction at 32° C and 1.5 to 1 in the cross-direction at 121 °
C.
The fourth membrane, PoreflonTM, is an expanded polytetrafluoroethylene (PTFE) produced by Sumitomo Electric Industries, Inc., Tokyo, Japan, which has a Gurley number of 17.5 ~ 0.5 seconds/100 cc.

SUBSTITUTE SHEET (RULE 26) In the preceding, Gurley number refers to a measure of the resistance to gas flow of a membrane, expressed as the time necessary for a given volume of gas to pass through a standard area of the membrane under standard conditions, as specified in ASTM D726-58, Method A. Gurley number is the time in seconds for 100cc of air, or another specified volume, to pass through 6.35 cm2 (one square inch) of a film at a pressure of 124 mm of water. The film sample is clamped between cylindrical rings, the uppermost of which contains a piston and the specified volume of air. When released, the piston applies pressure, under its own weight, to the air in the upper cylinder and the time taken for the specified volume of air to pass through the membrane is measured.
In the preceding, pore size refers to a measure of size of the largest pore in a membrane as specified in ASTM F-316-80. A liquid is used to fill the pores of the film. Air pressure is applied until air flows through the largest passageways in the film and appears as bubbles. The pressure at the point that bubbles appear is related to the size of the largest pores and the surface tension of the test liquid.
Using ethanol as a test liquid, the bubble point in micrometers is equal to 1.34 x 10' 3 divided by the pressure in Pascals (Pa) at which bubbles appear.
These polymer electrolytes are used in the following examples:
NafionTM 1100 solution: a solution of I 100 equivalent weight perfluorinated ion-exchange polymer having a S03 anion groups attached, produced by DuPont and available from ElectroChem, Inc., Woburn, MA, and Aldrich. Solution of 5 wt% in a mixture of lower aliphatic alcohols and water (15-20 % water).
p-STSI: An ion conductive material derived from free radical polymerization of styrenyl trifluoromethyl sulfonylimide (STSI); styrenyl-SOZN' (SOZCF3).
Examples 1 and 2 Examples 1 and 2 illustrate partial filling of the porous membranes with electrolyte using a multiple dipping and drying process. In this approach the porous membrane was immersed in low concentration electrolyte solution for short SUBSTITUTE SHEET (RULE 26) WO 99/19930 PC1'/US98/18654 times, dried in an air oven, and the process repeated multiple times, with measurements of the mass loading increase in between.
In Example 1, three sample discs of the TIPS membrane B, 3.81 cm in diameter, were immersed in 5 wt% Nafion 1100 solution, removed, dried and weighed and the change in mass of each sample disc recorded. This procedure was repeated a total of 16 times. The duration of the immersion was varied, from as much as 20 minutes to as little as 2 minutes. Drying was accomplished in an air oven at about 50°C. The drying time was also varied, usually being between 15 and 20 minutes, but being as long as 2 hours in one case. Fresh solution was used after the sixth and eleventh dippings. After removal from the solution, the excess was allowed to drip off the discs before drying. A summary of the samples' masses after each such dip and dry procedure is shown in Fig. 1. After the 15'~
dipping and drying, a wet cloth was used to further clean away any excess solution and the samples were weighed again (data point 16 in Fig. 1 ). Surface accumulation, which appears as a glossy coating, was absent after the wiping. The measurements indicate that the mass increases for all three samples were similar, increasing on average monotonically with dip number, more rapidly at first and then leveling off.
The length of soaking time does not appear to be a significant parameter and the use of fresh solutions does not appear to have a significant effect. Finally, the mass increase does not appear to be due to accumulation on the surface, since wiping caused a negligible decrease in weight relative to the overall increase in weight.
The average overall mass increase for the 16 dip/dry cycles is about 20 mg, or 1.75 mg/cm2, or 0.61 g/cm3. The density of the Nafion 1100 electrolyte is approximately 2 g/cm3, based on the density of Nafion 117, (1.97 g/cm3) which is the polymeric electrolyte material of Nafion 1100 out of solution. The density increase of 0.61 g/cm3 corresponds to filling about 30% of the volume of the membrane. Hence, the original void volume of the membrane, 58%, was approximately half filled by the multiple dipping/drying procedure.
This approach is readily adaptable to a continuous web filling process, wherein the membrane passes over a series of rollers in a serpentine fashion, passing into and out of a tank of electrolyte solution, with drying stations in between. The web would alternately be immersed in the electrolyte solution , pass SUBSTITUTE SHEET (RULE 26) WO 99/19930 PCT/US98/18654 _ out through drying stations (e.g. forced air or heat lamps), pass into the solution again and so on a desired number of times.
In Example 2, the multiple dipping and drying procedure of Example 1 was repeated with three sample discs of the TIPS membrane C medium. The number of cycles was eleven. The immersion times varied from 4 minutes to 20 minutes and drying times from 18 minutes to 90 minutes. Fig. 2 summarizes the mass changes after each cycle. Again, the measurements indicate that the mass increases for all three samples were similar, that the length of soaking time does not appear to be a significant parameter and that the use of fresh solutions does not appear to have a significant effect. The mass increase is similar for all three samples and appears to level off after the 40' cycle. The average overall mass increase is about 12 mg, or lmg/cm2, or 0.15 g/cm'. The TIPS membrane C medium has a smaller pore size and void volume (44%) than the TIPS membrane B medium which may account for the larger increase in density of the latter medium in Ex. 1. The maximum possible density increase is calculated to be 0.88 g/cm' of Nafion in the TIPS
membrane C medium. The density increase of 0.15 g/cm' corresponds to filling about 7.5% of the volume of the membrane. Approximately a sixth of the original void volume of the membrane, 44%, was filled by the multiple dipping/drying procedure.
E~ples 3-5 Examples 3, 4 and 5 illustrate partial filling of the porous membranes with electrolyte using a long soak method. In this approach, the porous membrane was immersed in the electrolyte solution for prolonged periods exceeding 20 minutes, then dried in an air oven.
In Example 3, two 3.15 cm diameter discs of TIPS membrane B were filled by soaking in 5 wt% Nafion solution for 30 minutes, then dried in an air oven at 50° C for 50 minutes. The density increases were 0.31 g/cm' and 0.26 g/cm' respectively, averaging 0.29 g/cm'.
In Example 4, a 3.81 cm diameter disc of TIPS membrane B was soaked for 5 hours in a 5 wt% solution. The container was not covered, so that the SUBSTITUTE SHEET (RULE 26) concentration could increase with time. After drying in an air oven for 45 minutes at about 50° C; the density increase was 0.44 g/cm'.
In Example 5, two, 2.5 cm diameter discs of TIPS membrane A were soaked in 20 wt% p-STSI in DI water for 20 minutes. The excess was allowed to drain off and the discs were dried overnight. For both samples, the density increase was 0.16 g/cm'.
Examples 6-12 Examples 6-12 illustrate partial filling of the porous membranes with electrolyte by use of a vacuum procedure. In this approach a small vacuum is applied to the underside of the porous membrane supported on a filter flask support, to force various electrolyte concentrations through the membrane.
In Examples 6-8 portions of the 5 wt% Nafion solution were dried down to prepare 10 and 20 wt% solutions. For each solution, single discs of TIPS
membrane A, each 3.81 cm diameter, were placed over the holes in the flat bottom of a Coors D37 ceramic filter funnel inserted in the top of a 250 ml vacuum flask, connected via a rubber hose to a Venturi air device, Varian model 952-5096 (sold by Varian, Lexington, MA) to provide suction. Then 0.5 ml of solution was spread over the top of the membrane and vacuum was applied to pull solution through the membrane. For the most viscous solution, not all solution passed through but remained on the surface of the membrane. The samples were dried for 35 minutes at about 50°C and weighed. The increase in mass due to electrolyte uptake was observed to increase monotonically with solution concentration finm 0.20 g/cm' at Swt% to 0.36 glcm' at 10 wt% to 0.71 g/cm' at 20 wt%. Since any excess left on the surface was not removed for the 20 wt% sample, part of the density increase is due to a dried film left covering the surface.
In Example 9, the TIPS membrane B was filled with Nafion 5 wt% solution in the same apparatus described in Ex. 6. Sample diameters were 3.15 cm. 15 drops of solution were added to the first discs. The solution was allowed to wet the TIPS for 2 minutes, then vacuum was applied for 10 seconds. For the second disc, 17 drops were applied for 3 minutes before vacuum was applied for 50 seconds.

SUBSTITUTE SHEET (RULE 26) WO 99/19930 pCT/US98/18b54 After drying the density increases were measured to be 0.26 g/cm' and 0.35 g/cm' respectively.
In Example 10, two 3.81 cm diameter discs of TIPS membrane C were vacuum loaded with 5 wt% Nafion solution. 15 drops were applied to each surface, allowed to wet for one minute, then vacuum applied for 17 seconds in one case and SO seconds in the second sample. The samples were dried at 50°
C for 25 minutes. The density increases were 0.06 g/cm3 and 0.054 g/cm3 respectively.
In Example 11, three discs, each 3.51 cm diameter, of the TIPS membrane A were partially filled with Nafion using 5 wt% solutions and the vacuum pull through method of Ex. 6. For the first disc; a total of 1 ml of solution was passed through, in two 15 drop lots. For the second 2 ml of solution was passed through and for the third, 3 ml was used. After drying the respective density increases were 0.298 g/cm' , 0.301 g/cm' and 0.303 g/cm3. Example 11 demonstrates that the increase in density observed using the vacuum method, and hence the amount of ionomer adsorbed, becomes independent of the total volume of electrolyte solution passed through the membrane.
In Example 12, two 2.5 cm discs of TIPS membrane A were filled with p-STSI from a 20 wt% solution using the same procedure as in Example 6. Six drops of solution were added to the surface and vacuum applied for 2 minutes. After drying, the change in density was 0.17 g/cm' and 0.13 g/cm', averaging 0.15 g/cm'.
Examples 13-19 Examples 13-19 illustrate partial filling of the porous membranes with electrolyte using positive pressure provided by a hydraulic press. In the hydraulic press approach, a room temperature mechanical press is used to hydraulically force high concentration (viscous) electrolyte solutions through the porous membrane.
In the following Examples, two pieces of 100 micrometer thick polyethylene terephthalate (PET) film were prepared as masks by cutting 3.7 cm diameter holes in their centers. The porous membrane material was sandwiched between the two PET masks. This sandwich was further sandwiched between two sheets of 0.025 cm thick PTFE, after applying the electrolyte solution into the volume (about 0.1 ml) defined by the holes in the PET mask. This sandwich was SUBSTITUTE SHEET (RULE 26) WO 99/19930 pCT/US98/18654 _ placed between stainless steel shim stock. The entire assembly was placed between the platens of a hydraulic press (manufactured by Fred S. Carver, Inc., Wabash, III and a force of 3.2 tons applied for 3-5 minutes at mom temperature.
After pressing, excess solution was wiped off the surface of the membrane and the latter dried in an air oven at about 48° C for 12 minutes. A disc of measured diameter was die cut from the center of the partially filled membrane sample and its mass loading of electrolyte gravimetrically determined.
In Example 13, two samples of TIPS membrane B were filled with Nafion using a 5 wt% solution and the procedure described above and 3.1 S cm diameter discs were die cut from the resulting membrane. The density increases after drying were 0.11 g/cm' and 0.076 g/cm', averaging 0.093 g/cm'.
In Example 14, two samples of the TIPS membrane C were filled with Nafion using a 5 wt% solution and the same procedure as in Ex. 13 and 3.81 cm diameter discs were die cut fibm the resulting membrane. The density increases after drying were 0.037 g/cm3 and 0.045 g/cm3, averaging 0.041 g/cm'.
In Example 15, the hydraulic press method described in Example 13 was used to fill 3 samples of TIPS membrane B with p-STSI from 20 wt% solutions in 70/30 methanol and water. Three to four drops of solution were used for each side, pressed for 3 minutes at 3 tons, then dried 20 minutes at about 50° C
after wiping the excess electrolyte offthe surface. Three 3.25cm diameter discs were cut from the resulting membranes. The density increases were 0.049 g/cm', 0.014 g/cm' and 0.060 g/cm' for an average increase of 0.041 g/cm'.
In Example 16, the procedure of Example 15 was repeated with two more samples, using 4 drops on each side from a 20 wt% solution of p-STSI in water only. The excess was wiped off and the samples dried at 55-60°C for 23 minutes, and 3.81 cm diameter disks were cut from the resulting membranes. The density increase were 0.028 g/cm' and 0.19 g/cm' for an average increase of 0.11 g/cm3.
In Examples 17 and 18, the procedures used in Examples 15 and 16 were repeated using, three TIPS membrane C sample discs with 20 wt% solution of p-STSI in 70/30 MeOH/H20, for 17 and two sample discs with p-STSI in pure water, for 18. The density increases of the first three discs were 0.098 g/cm', 0.091 SUBSTITUTE SHEET (RULE 26) g/cm3 and 0.149 g/cm' averaging 0.1 I3 g/cm'. The increases of the next two were 0.25 g/cm' and 0.088 g/cm' averaging 0.17 g/cm'.
In Example 19, a 3.85 cm diameter disc of 50 micrometer thick PoreflonTM
was filled using the procedure of Ex. 13. The porosity of the as received Poreflon was characterized by Gurley measurements and found to be 17.5 t 0.5 seconds/100 cc. Fifteen drops of a 14 wt% solution of Nafion 1100 was added to one side of the membrane (in the volume defined by the 100 micrometer thick PET mask aperture) and pressed at 2 tons for 4 minutes at room temperature. The excess Nafion was wiped off and the membrane dried at 49°C for 15 minutes. The density increase was 0.22 g/cm'. The Gurley number of the filled sample was measured to be over 900 seconds/4 cc, corresponding to 22,500 seconds /100cc.
Summary of Density Increase Data Examples 1-19 demonstrate the density increase due to electrolyte incorporation by the various porous membranes for four filling procedures.
Table I, below, summarizes the average results for Examples (including Example 20, below) that used Nafion electrolyte with four different porous membranes and four different methods. Table II, below, summarizes the average results for Examples (including Example 24, below) that used pSTSI electrolyte with three different porous membranes and three different methods.

SUBSTITUTE SHEET (RULE 26) Table I. Summary of density increases in g/cm' of four different porous membranes filled from NafionTM solution using four different procedures.
Filling MethodTIPS TIPS 'TIPS PoreflonTM

membrane me~tnbrane membrane A B C

Multi-Dip 0.61 (Ex. 0.15 (Ex.
and 1) 2) Long Soak 0.29 (Ex.
3) 0.44 (Ex.
4) Vacuum - 0.20 (Ex. 0.31 (Ex. 0.057 ( 6) 9) Ex. 10) 0.36 (Ex.
7) 0.71 (Ex.
8) 0.301 (Ex.
11) Hydraulic 0.35 (Ex. 0.093 (Ex. 0.041 (Ex. 0.22 (Ex.
Press 20) 13) 14) 19) Table II. Summary of density increases in g/cm' of three different porous membranes filled from p-STSI solution using three different procedures.
Filling MethodTIPS TIPS TIPS
membrane A membrane B membrane C

Long Soak 0.16 (Ex.
5) Vacuum 0.15 ( Ex.
12) Hydraulic 0.15 (Ex. 0.041 (Ex. 0.113 (Ex. 17) press 24) 15) 0.17 (Ex. 18) 0.109 (Ex.
16) Examples 20-25 Examples 20-25, following, demonstrate partial filling of the membranes followed by pressing of the partially filled membranes with electrode particles to form membrane electrodes. The electrode particles used in Examples 20-25 are nanostructured catalyst particles consisting of catalyst materials, e.g. Pt, conformally coated onto nanometer sized whisker-like supports, as described above and in US 5,338,430 and other patents referenced therein, incorporated herein by reference. The whiskers used herein were produced by vacuum SUBSTITUTE SHEET (RULE 2fi) annealing thin films (about 1000-1500 Angstroms) of perylene red (PR149, described above) previously vacuum coated onto substrates such as polyimide.
The whisker-like supports, with lengths of about 1-2 micrometers, were grown with uniform cross-sectional dimensions of about 30 - 60 nanometers, end-s oriented on a substrate to form a dense film of closely spaced supports (about 30-40 per square micrometer) for transfer into the surface of a polymer electrolyte to form the catalyst electrode, as described below. The nanostructured catalyst electrode has a very high surface area which is readily accessible to fuel and oxidant gases.
Example 20 In Example 20, two 7.6 x 7.6 cm square pieces of 100 micrometer thick PET film were prepared as masks by cutting 3.7 cm diameter holes in their centers.
A 7.6 cm x 7.6 cm piece of the TIPS membrane A porous membrane material was sandwiched between the two PET masks. This sandwich was fiirther sandwiched between two sheets of 0.025 cm thick Teflon, after applying 6 to 7 drops of a wt % Nafion 1100 solution into the volume ( about 0.1 ml) defined by the PET
mask holes. The 25 wt% Nafion solution was obtained from the purchased 5 wt%
solution by solvent evaporation. This sandwich was placed between stainless steel shim stock . The entire assembly was placed between the platens of a Carver press and a force of 3.2 tons applied for 5.0 minutes at room temperature. Assuming about 30 drops/ml, the 6-7 drops should represent an excess by about a factor of two over what is needed to fill the 70% void volume of the membrane, assuming that all of the volume was accessible. After pressing, excess Nafion solution was wiped off the surface of the membrane and the latter dried in an air oven at about 48 C for 12 minutes. A 3.5 cm diameter disc was die cut from the center of the filled membrane and its mass loading of Nafion gravimetrically determined to be 2.88 mg/cm~, or 0.32 g/cm'.
The Gurley number of the as-received TIPS membrane A was measured to be 8 secs/100cc. In order to obtain the Gurley number of the filled membrane, a second sample of the TIPS membrane A was partially filled using the Carver press and 14 % Nafion solution with the same procedure as described above. The SUBSTITUTE SHEET (RULE 26) Gurley number for this sample, without attached electrodes, was measured to be over 900 secs/3cc, corresponding to 30,000 sec/100cc.
Next, a three layer membrane electrode assembly, comprising an electrode layer, an ICM, and a second electrode layer, was formed by using heat and pressure to transfer nanostructured electrode particles from a polyimide substrates into both surfaces of the partially filled membrane. The filled membrane disc was placed between two sheets of polyimide-supported nanostructured films of nanostructured elements. These elements, which were PR149 whiskers coated with a mass equivalent layer thickness of first 3000 Angstroms of Ni and secondly, 1000 Angstroms of Pt, were placed against the partially filled membrane. Additional layers of uncoated polyimide and PTFE sheets were further layered on either side of the sandwich for uniform distribution of pressure, and finally a pair of stainless steel shims were placed outside of this assembly. The assembly was placed between the heated platens of a mechanical press (Carver 6" press) at low pressure, allowed to equilibrate to 99°C for several minutes, pressed at 15.1 MPa (0.17 tons/cmz) for 90 seconds, left under pressure while the platens were water cooled for several minutes, then removed. The original polyimide substrates were then peeled away from the membrane. The transfer of catalyst particles was complete and very uniform.
Fig. 3 is a scanning electron micrograph taken at 2000X magnification of the surface of the as-received TIPS membrane A material used in Example 20, viewed from the top, showing the large degree of porosity.
Fig. 4 is a scanning electron micrograph taken at 1000X of a cross-section of the MEA, showing that the thiclrness of the membrane electrode assembly is now about 33 micrometers, having been reduced from the initial membrane thickness of about 89 micrometers.
Fig. 5 is a scanning electron micrograph taken at SOOOX of one of the electrode sides showing the electrode particles embedded in the membrane. The fractured edge of the membrane shows some evidence of the fibril nature of the original polypropylene matrix.
For comparison, a portion of the membrane that was not filled with Nafion was impregnated with electrode particles. Fig. 6 is a scanning electron micrograph SUBSTITUTE SHEET (RULE 26) taken at 4000x showing that the thickness of this portion was reduced to about micrometers, or about 1/6°' the original thickness. In contrast, the membrane was only compressed to about 1/3'~ the original thickness after the partial filling step.
Exam l~l In Example 21, two 7.6 x 7.6 cm square pieces of 50 micrometer thick polyimide film were prepared as masks by cutting 2.23 cm x 2.23 cm square holes (5 cm2 in area) in their centers. A 7.6 cm x 7.6 cm piece of the TIPS membrane A
porous membrane material was sandwiched between the two polyimide masks.
After application of 6 to 7 drops of a 14 wt % Nafion 1100 solution into the volume defined by the square holes, this sandwich was further sandwiched between two whole sheets of the poiyimide and finally two sheets of 0.025 cm thick Teflon. This sandwich was placed between stainless steel shim stock and the entire assembly placed between the platens of a Carver press. A force of 3.2 tons 1 S was applied for 3 minutes at room temperature. After pressing, the outer polyimide layers were removed and excess Nafion solution was wiped off the surface of the TIPS membrane in the area defined by the square holes, the TIPS being left sandwiched between the initial polyimide masks. The assembly was dried in an air oven at about 48 C for 25 minutes.
An MEA was formed using nanostructured films composed of electrode particles supported on a polyimide substrate. The nanostructured electrode particles used in Example 21 were supported on a polyimide substrate, as in Ex.
20, but were coated with 1000 Angstroms mass equivalent of Pt, rather than Ni and then Pt. Square pieces of the polyimide supported nanostructured films, S cm2 in area, were placed in each square hole of the masks. The assembly was preheated to 210-215° C, pressed at 14.2 MPa (0.12 tons/cm2) for one minute, and cooled under pressure. The polyimide substrates supporting the whiskers were peeled away leaving the Pt coated nanostructure in the 5 cm2 area of the filled membrane.
SEM
micrographs show the compressed 3-layer MEA to be 31 micrometers thick and demonstrate that the pressing process embedded the nanostructured electrode particles in the surface of the filled membrane.

SUBSTITUTE SHEET (RULE 2fi) WO 99/19930 PCT/IJS98/18654 _ To make a fuel cell from this MEA, each 5 cm2 electrode area of the 3 layer MEA was covered with an equivalent sized square of a carbon-only ELATTM
material, available from Etek, Inc., Natick, MA. as a fuel cell electrode backing material. The FLAT is a composite made of a woven carbon cloth and a carbon black/Teflon coating. The resulting five-layer cell was mounted in a fuel cell test fixture supplied by Fuel Cell Technologies, Inc., Albuquerque, NM, which is made to accept the size and shape of the MEA. The five layer MEA was tested with HZ/oxygen gas flows applied to the respective electrodes using a fuel cell test station from Fuel Cell Technologies, Inc.
Fig. 7, curve A shows an initial polarization curve of voltage versus current density produced by the fuel cell assembly of this example under hydrogen and oxygen pressures of 63 kPa absolute (9 psig) and 327 kPa absolute (18 psig), respectively, a cell temperature of 40° C, and 200 scan flow rates.
1 S Example 22 In Example 22, a three layer MEA was prepared using the same TIPS
membrane A membrane partially filled with Nafion, the same type of nanostructured electrodes and the same procedures as described in Example 21.
However, prior to attaching nanostructured electrodes, an additional drop of 5 wt%
Nafion solution was applied to each area of filled membrane exposed thmugh the Scm2 square holes of the polyimide masks, and dried at 40° C for 15 minutes. Pt coated electrode particles were attached as in Ex. 21. In this instance, the Pt coated electrode particles are embedded into the thin surface layer of solution cast Nafion left on the surface of the filled membrane. Assuming 30 dmps per ml, the dried thickness of the cast Nafion layer would be about 3 micrometers. The nanostructure electrode particles are about 1 to 2 micrometers long and about 60 nm wide.
The 3-layer MEA was tested as a fuel cell MEA with ELAT electrode backings, as described in Example 21. Curve B in Fig. 7 shows a polarization curve example under hydrogen/oxygen pressures of 170/205 kPa absolute (10/15 psig), a cell temperature of 70° C, and 200 sccm flow rates. After completing the tests, the MEA of this example was thoroughly dried. Its thickness was measured SUBSTITUTE SHEET (RULE 26j to be 25 micrometers, suggesting further compression of the membrane than in Example 21.
Examples 23-25 In Examples 23-25, MEAs were formed using p-STSI electrolyte in TIPS
membrane A by two different loading processes and the MEAs were evaluated in a fuel cell. In both Examples, an unexpected change in the morphology of the membrane is demonstrated.
In Example 23, a 20 wt% solution of p-STSI in a 70/30 v/v mix of MeOH
and water was prepared. A 2.5 cm diameter disc of the TIPS membrane A was placed over the holes in the flat bottom of a Coors D37 ceramic filter funnel inserted in the top of a 250 ml vacuum flask, connected via a rubber hose to a Venturi air device to provide suction. Six drops of the solution were applied to the TIPS disc and air pressure applied to the Venturi device sufficient to pull the solution through the membrane, which process took about 8 seconds. After drying, the disk was about 75 micrometers thick at its center. Fig. 9 is a scanning electron micrograph taken at 1000X magnification of the top surface of the membrane. After being partially filled with p-STSI, illustrating a significant degree of open porosity still existing in the membrane.
Pt coated electrode particles similar to those described in Example 21 were pressed into the partially filled membrane using 18.9 MPa (0.16 tons/cm2) pressure at 110° C, by preheating for 1 minute, pressing for 1 minute and cooling under pressure for 4 minutes. Fig. 10 is a cross-sectional scanning electron micrograph taken 1000X magnification showing that the MEA thickness is reduced to 59 micrometers from the initial 89 micrometers. Surprisingly, the membrane now appears to be homogeneous and lacks any indication of the initial porosity.
This uniformity is still seen at 10,000X magnification, in Fig. 11. Fig. 11 also shows the nanostructured electrode particles embedded in the surface of the membrane.
The fact that the process of embedding the nanostructured electrode particles to form an MEA has so dramatically changed the morphology of the membrane interior was unexpected. Whereas the TIPS membranes coated from NafionTM
solution are observed under SEM to have the ionomer coated onto the fibrils of the SUBSTITUTE SHEET (RULE 26) porous membrane, it appears that the p-STSI has preferentially filled the pore voids as well as wetting the surface of the pore walls.
In Example 24, a 2.5 cm disc of TIPS membrane A membrane was partially filled with the same p-STSI solution as in Example 4, but using the S hydraulic press method and PET masks as described in Ex. 11. Five drops of the solution were added to both sides of the 2.5 cm apertures in the PET masks to wet the exposed membrane, and pressed at room temperature with 3 tons for 3 minutes.
The excess was wiped off the surface and the sample dried in an air oven at 50° C
for 30 minutes. The mass loading of p-STSI was measured to be 1.1 mg/cmz or 0.15 g/cm'. An MEA was formed by embedding the same Pt coated nanostructured film as in Ex. 23, using 84 MPa (0.71 tons/cm2) pressure at the same pressing conditions used in Ex. 23. Fig. 12 is a cross-sectional scanning electron micrograph taken at showing the compressed MEA thickness to be 28 micrometers. Fig. 12 shows the internal membrane structure to be substantially homogeneous along its outer layers, as in Figs. 10, but that some of the porous structure is still evident in the central portion, perhaps due to incomplete penetration of the electrolyte. However, no membrane-crossing pores are evident in Fig. 12.
In Example 25, the same filling procedure and similar electrode attachment procedures were followed as in Example 24. The electrode attachment was accomplished with 106.5 MPa (0.9 tons/cmz) pressure at 230°F for 1 minute with 5 minutes preheating and 5 minutes cooling under pressure. The fuel cell MEA
sample was prepared in a square aperture between polyimide masks, the aperture being 5 cm2 in area. The fuel cell MEA sample was tested as described in Ex.
20.
Fig. 8 shows a polarization curve obtained at 50°C and S psig H2/02 pressures.
Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the scope and principles of this invention, and it should be understood that this invention is not to be unduly limited to the illustrative embodiments set forth hereinabove.

SUBSTITUTE SHEET (RULE 26)

Claims (10)

We claim:
1. A method of making a membrane electrode assembly comprising the steps of:
a) partially filling a porous membrane with an ion conducting electrolyte to form a partially filled membrane; and b) compressing together said partially filled membrane and electrode particles so as to remove void volume from said partially filled membrane and embed said electrode particles in said partially filled membrane.
2. The method according to claim 1, wherein said electrode particles are nanostructured elements.
3. The method according to any of claims 1 or 2, wherein said porous membrane is polypropylene and is prepared by thermally-induced phase separation (TIPS).
4. The method according to any of claims 1 to 3, wherein the step of partially filling the porous membrane comprises at least one immersion step, comprising a) immersing the porous membrane in a solution of the ion conducting electrolyte and then b) drying the membrane.
5. The method according to any of claims 1 to 3, wherein the step of partially filling the porous membrane comprises mechanically compressing together the porous membrane and a solution of the ion conducting electrolyte.
6. The method according to any of claims 1 to 3, wherein the step of partially filling the porous membrane comprises forcing a solution of the ion conducting electrolyte into the porous membrane by air pressure differential.
7. A composite membrane made according to the method of any of claims 1 to 6, comprising a polymer which comprises the polymerization product of monomers including a monomer having the structural formula CH2=CH-Ar-SO2-N--SO2(C1+n F3+2n), wherein n is 0-11 and wherein Ar is any substituted or unsubstituted aryl group.
8. The composite membrane according to claim 7 comprising polystyrenyl trifluoromethyl sulfonylimide (p-STSI).
9. A composite membrane made according to the method of any of claims 1 to 6, comprising a porous membrane and polymeric ion conducting electrolyte, wherein the polymeric ion conducting electrolyte fills the pore voids to the extent that no porous structure is visible under scanning electron microscopy at magnifications of up to 10,000X.
10. An electrochemical device comprising the membrane electrode assembly according to any of claims 1 to 9.
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Families Citing this family (98)

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Publication number Priority date Publication date Assignee Title
US6042959A (en) * 1997-10-10 2000-03-28 3M Innovative Properties Company Membrane electrode assembly and method of its manufacture
US6136412A (en) * 1997-10-10 2000-10-24 3M Innovative Properties Company Microtextured catalyst transfer substrate
US5910378A (en) * 1997-10-10 1999-06-08 Minnesota Mining And Manufacturing Company Membrane electrode assemblies
US6277512B1 (en) 1999-06-18 2001-08-21 3M Innovative Properties Company Polymer electrolyte membranes from mixed dispersions
US6479188B1 (en) * 1999-10-13 2002-11-12 The Gillette Company Cathode tube and method of making the same
US6586133B1 (en) * 2000-02-21 2003-07-01 The University Of Tulsa Nano-battery systems
US20030051992A1 (en) * 2000-05-16 2003-03-20 Earthfirst Technologies, Inc. Synthetic combustible gas generation apparatus and method
JP4974403B2 (en) 2000-05-31 2012-07-11 日本ゴア株式会社 Solid polymer electrolyte fuel cell
US6627035B2 (en) 2001-01-24 2003-09-30 Gas Technology Institute Gas diffusion electrode manufacture and MEA fabrication
JP2002280012A (en) * 2001-03-15 2002-09-27 Matsushita Electric Ind Co Ltd Method of manufacturing for electrolyte membrane electrode joint body for fuel cell
KR100397954B1 (en) * 2001-03-20 2003-09-13 한국과학기술원 Manufacturing Method of Polymer Electrolyte Membrane for Fuel Cells
DE10118651A1 (en) * 2001-04-14 2002-10-24 Daimler Chrysler Ag Fuel cell comprises electrodes consisting of electrically conducting regularly arranged needle-like or tubular electrode elements anchored on a gas-permeable supporting substrate and coated with a catalyst
US6733909B2 (en) 2001-05-03 2004-05-11 Ford Motor Company Fuel cell power plant with electrochemical enhanced carbon monoxide removal
US6689501B2 (en) 2001-05-25 2004-02-10 Ballard Power Systems Inc. Composite ion exchange membrane for use in a fuel cell
US6582429B2 (en) * 2001-07-10 2003-06-24 Cardiac Pacemakers, Inc. Ablation catheter with covered electrodes allowing electrical conduction therethrough
US20060177720A1 (en) * 2001-08-20 2006-08-10 Hae-Kyoung Kim Reinforced composite ionic conductive polymer membrane, fuel cell adopting the same, and method of making the same
US6898404B2 (en) * 2001-08-21 2005-05-24 Pfu Limited Liquid development electrophotographic device
US6613203B1 (en) * 2001-09-10 2003-09-02 Gore Enterprise Holdings Ion conducting membrane having high hardness and dimensional stability
US6838205B2 (en) * 2001-10-10 2005-01-04 Lynntech, Inc. Bifunctional catalytic electrode
KR100441376B1 (en) * 2002-01-31 2004-07-23 (주)퓨얼셀 파워 A very thin Composite membrane
US7432009B2 (en) * 2002-04-03 2008-10-07 3M Innovative Properties Company Lamination apparatus and methods
US6868890B2 (en) * 2002-04-03 2005-03-22 3M Innovative Properties Company Method and apparatus for peeling a thin film from a liner
US6740131B2 (en) * 2002-04-03 2004-05-25 3M Innovative Properties Company Apparatus for automatically fabricating fuel cell
US20030188616A1 (en) * 2002-04-03 2003-10-09 Behymer Lance E. Compliant cutting die apparatus for cutting fuel cell material layers
US20030188615A1 (en) * 2002-04-03 2003-10-09 3M Innovative Properties Company Angled product transfer conveyor
US20040020785A1 (en) * 2002-07-31 2004-02-05 Minteer Shelley D. Magnetically-enhanced electrolytic cells for generating chlor-alkali and methods related thereto
KR100484499B1 (en) * 2002-08-21 2005-04-20 한국과학기술원 Composition of Polymer Electrolytes for Direct Methanol Fuel Cell
US6787007B2 (en) * 2002-09-23 2004-09-07 Bechtel Bwxt Idaho, Llc Polymeric hydrogen diffusion barrier, high-pressure storage tank so equipped, method of fabricating a storage tank and method of preventing hydrogen diffusion
US7037319B2 (en) * 2002-10-15 2006-05-02 Scimed Life Systems, Inc. Nanotube paper-based medical device
US20040175498A1 (en) * 2003-03-06 2004-09-09 Lotfi Hedhli Method for preparing membrane electrode assemblies
US7590175B2 (en) 2003-05-20 2009-09-15 Rambus Inc. DFE margin test methods and circuits that decouple sample and feedback timing
US7195690B2 (en) 2003-05-28 2007-03-27 3M Innovative Properties Company Roll-good fuel cell fabrication processes, equipment, and articles produced from same
CN100373678C (en) * 2003-07-03 2008-03-05 许纲 Integrated membrane electrode for electrochemical apparatus and mfg. method thereof
US7338692B2 (en) * 2003-09-12 2008-03-04 3M Innovative Properties Company Microporous PVDF films
US20050142280A1 (en) * 2003-10-20 2005-06-30 Kim Kwon I. System and method for synthesizing a polymer membrane
US7048889B2 (en) * 2004-03-23 2006-05-23 Lucent Technologies Inc. Dynamically controllable biological/chemical detectors having nanostructured surfaces
KR100696680B1 (en) * 2004-06-30 2007-03-19 삼성에스디아이 주식회사 Polymer membrane for fuel cell and method for preparating the same
US20060105219A1 (en) * 2004-11-15 2006-05-18 Anderson Robert D Fuel cell component storage or shipment
US7608118B2 (en) * 2004-11-15 2009-10-27 3M Innovative Properties Company Preconditioning fuel cell membrane electrode assemblies
US20060128557A1 (en) * 2004-12-14 2006-06-15 Mackinnon Sean M Manufacturing method for electrochemical fuel cells
JP5265926B2 (en) * 2005-02-16 2013-08-14 スリーエム イノベイティブ プロパティズ カンパニー Fuel cell catalyst
JP5176318B2 (en) * 2005-02-17 2013-04-03 東レ株式会社 Aromatic polyamide porous film, method for producing aromatic polyamide porous film, and secondary battery
JP5283826B2 (en) * 2005-03-02 2013-09-04 キヤノン株式会社 Membrane electrode assembly and polymer electrolyte fuel cell
US20060199069A1 (en) * 2005-03-02 2006-09-07 Canon Kabushiki Kaisha Membrane electrode assembly, method for manufacturing the same, and polymer electrolyte fuel cell
JP4810841B2 (en) * 2005-03-04 2011-11-09 大日本印刷株式会社 Method and apparatus for producing electrolyte membrane-catalyst layer assembly for polymer electrolyte fuel cell
CN100344350C (en) * 2005-04-19 2007-10-24 武汉理工大学 Prepn process of polymer reinforced porous proton exchange membrane
US7214740B2 (en) * 2005-05-03 2007-05-08 3M Innovative Properties Company Fluorinated ionomers with reduced amounts of carbonyl end groups
US7666494B2 (en) * 2005-05-04 2010-02-23 3M Innovative Properties Company Microporous article having metallic nanoparticle coating
US8574744B1 (en) 2005-05-13 2013-11-05 The University Of Tulsa Nanoscale three-dimensional battery architecture
US7736724B1 (en) 2005-05-13 2010-06-15 The University Of Tulsa Fabrication of nanobaskets by sputter deposition on porous substrates and uses thereof
JP4508954B2 (en) * 2005-06-08 2010-07-21 本田技研工業株式会社 Membrane-electrode structure for polymer electrolyte fuel cell
JP2009501095A (en) * 2005-07-14 2009-01-15 スリーエム イノベイティブ プロパティズ カンパニー Water-soluble polymer substrate with metallic nanoparticle coating
JP4674805B2 (en) * 2005-07-14 2011-04-20 日立粉末冶金株式会社 Method for producing electrode material for cold cathode fluorescent lamp
US8652705B2 (en) * 2005-09-26 2014-02-18 W.L. Gore & Associates, Inc. Solid polymer electrolyte and process for making same
US7833645B2 (en) * 2005-11-21 2010-11-16 Relion, Inc. Proton exchange membrane fuel cell and method of forming a fuel cell
CN101317296A (en) * 2005-12-01 2008-12-03 加利福尼亚大学董事会 Functionalized inorganic films for ion conduction
CN100461502C (en) * 2005-12-31 2009-02-11 山东理工大学 Method for preparing weak alkaline membrane of direct alcohols fuel cell
KR100846072B1 (en) * 2006-01-04 2008-07-14 주식회사 엘지화학 Membrane Electrode Assembly Having Layer for Trapping Catalyst and Fuel Cell Employed with the Same
US8137750B2 (en) * 2006-02-15 2012-03-20 3M Innovative Properties Company Catalytically active gold supported on thermally treated nanoporous supports
KR20090003218A (en) * 2006-02-15 2009-01-09 쓰리엠 이노베이티브 프로퍼티즈 컴파니 Selective oxidation of carbon monoxide relative to hydrogen using catalytically active gold
CN100405053C (en) * 2006-03-23 2008-07-23 广州杰赛科技股份有限公司 Co-burning method for oxygen sensor electrolyte and porous film
US7906251B2 (en) * 2006-04-20 2011-03-15 3M Innovative Properties Company Oxygen-reducing catalyst layer
US7740902B2 (en) * 2006-04-20 2010-06-22 3M Innovative Properties Company Method for making oxygen-reducing catalyst layers
US7842153B2 (en) * 2006-06-23 2010-11-30 Atomic Energy Council-Institute Of Nuclear Energy Research Decal method for transferring platinum-and platinum alloy-based catalysts with nanonetwork structures
US7753978B2 (en) * 2006-06-30 2010-07-13 Caterpillar Inc Filter system
ATE524843T1 (en) 2007-04-12 2011-09-15 3M Innovative Properties Co POWERFUL AND DURABLE NON- PRECIOUS METAL FUEL CELL CATALYSTS
US8026020B2 (en) 2007-05-08 2011-09-27 Relion, Inc. Proton exchange membrane fuel cell stack and fuel cell stack module
US9293778B2 (en) 2007-06-11 2016-03-22 Emergent Power Inc. Proton exchange membrane fuel cell
KR100957302B1 (en) * 2007-09-07 2010-05-12 현대자동차주식회사 Method for manufacturing Membrane-Electrode Assembly
US8003274B2 (en) * 2007-10-25 2011-08-23 Relion, Inc. Direct liquid fuel cell
US8053035B2 (en) * 2007-10-26 2011-11-08 Fuelcell Energy, Inc. Electrode assembly and method of making same
AU2009205297A1 (en) 2008-01-17 2009-07-23 Syneron Medical Ltd. A hair removal apparatus for personal use and the method of using same
CN101237048B (en) * 2008-01-21 2010-12-08 重庆大学 Method for making sequential anti-drowning gas multi-hole pole
CN101237049B (en) * 2008-01-22 2010-11-03 重庆大学 Making method for anti-drowning gas multi-hole pole in alkalescent medium
EP2237732A4 (en) 2008-01-24 2011-06-01 Syneron Medical Ltd A device, apparatus, and method of adipose tissue treatment
US20120022512A1 (en) * 2008-01-24 2012-01-26 Boris Vaynberg Device, apparatus, and method of adipose tissue treatment
JP5262893B2 (en) * 2008-04-24 2013-08-14 トヨタ自動車株式会社 Membrane electrode assembly manufacturing method and membrane electrode assembly manufacturing apparatus
US8535805B2 (en) * 2008-04-28 2013-09-17 The United States Of America, As Represented By The Secretary Of The Navy Hydrophobic nanostructured thin films
EP2330998A4 (en) * 2008-09-11 2013-01-23 Syneron Medical Ltd A device, apparatus, and method of adipose tissue treatment
AU2009294227B2 (en) * 2008-09-21 2012-07-19 Syneron Medical Ltd. A method and apparatus for personal skin treatment
JP4661943B2 (en) * 2008-11-15 2011-03-30 株式会社エクォス・リサーチ CO gas sensor
US20100255376A1 (en) * 2009-03-19 2010-10-07 Carbon Micro Battery Corporation Gas phase deposition of battery separators
US20100273093A1 (en) * 2009-04-23 2010-10-28 3M Innovative Properties Company Catalyst particle size control with organic pigments
KR101577828B1 (en) * 2009-07-13 2015-12-28 코오롱인더스트리 주식회사 Filling System used for preparation of Polymer Electrolyte Membrane and Method of manufacturing Polymer Electrolyte Membrane using the same
WO2012033539A1 (en) * 2010-09-10 2012-03-15 Hitachi Chemical Co., Ltd. Individually addressable band electrode arrays and methods to prepare the same
US20140246304A1 (en) 2011-10-10 2014-09-04 3M Innovative Properties Company Catalyst electrodes, and methods of making and using the same
KR20160102187A (en) * 2013-12-19 2016-08-29 트레오판 저머니 게엠베하 앤 코. 카게 ION-EXCHANGE MEMBRANE MADE OF A BIAXIALLY STRETCHED β-POROUS FILM
CN103739041B (en) * 2014-01-13 2015-03-25 中国电建集团中南勘测设计研究院有限公司 Electrode structure and electrolytic reaction cell
US11094953B2 (en) * 2015-05-26 2021-08-17 3M Innovative Properties Company Electrode membrane assembly having an oxygen evolution catalyst electrodes, and methods of making and using the same
KR102300222B1 (en) * 2016-04-13 2021-09-09 엠 히카리 앤 에너지 레보레토리 컴퍼니 리미티드 Electrochemical reaction device using on/off side switches of ions
CN106153707B (en) * 2016-06-22 2018-10-23 福建中医药大学 A kind of detection method of Herba Andrographitis class Andrographolide in Medicinal Preparations content
JP7273929B2 (en) * 2017-09-20 2023-05-15 株式会社東芝 Electrochemical reactor and porous separator
JP2019056136A (en) * 2017-09-20 2019-04-11 株式会社東芝 Electrochemical reaction device
US10756373B2 (en) * 2017-12-22 2020-08-25 Chinbay Q. Fan Fuel cell system and method of providing surfactant fuel bubbles
WO2019188960A1 (en) * 2018-03-29 2019-10-03 東レ株式会社 Composite electrolyte membrane
KR20190115956A (en) 2018-04-04 2019-10-14 현대자동차주식회사 Manufacturing method of electrolyte membrane having high-durability for fuel cell
EP3854913A4 (en) * 2018-09-21 2022-03-30 Asahi Kasei Kabushiki Kaisha Laminate, laminate storage method, laminate shipping method, protective laminate, and wound body thereof
CN114349127A (en) * 2022-01-10 2022-04-15 烟台大学 Stainless steel-based lanthanum/samarium/cerium dioxide anti-fouling electrode membrane and preparation process and application thereof

Family Cites Families (97)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL142204B (en) * 1965-02-01 1974-05-15 Tno PROCESS FOR MANUFACTURING ARTIFICIAL WIRES FROM HEAT-SENSITIVE POLYMERS AND WIRES THEREFORE OBTAINED.
US3442715A (en) * 1965-03-01 1969-05-06 Monsanto Res Corp Method of making diffusion membrane electrodes from visco elastic dough
US3676222A (en) * 1970-09-10 1972-07-11 Monsanto Res Corp Conductive carbon membrane electrode
US3969545A (en) * 1973-03-01 1976-07-13 Texas Instruments Incorporated Light polarizing material method and apparatus
JPS5146589A (en) * 1974-10-21 1976-04-21 Kureha Chemical Ind Co Ltd Shinkinakozo ojusuru ionkokanmaku oyobi sono seizoho
DE2616662C2 (en) * 1976-04-15 1984-02-02 Dornier System Gmbh, 7990 Friedrichshafen METHOD FOR PRODUCING A SELECTIVE SOLAR ABSORBER LAYER ON ALUMINUM
JPS52130491A (en) * 1976-04-27 1977-11-01 Toyo Soda Mfg Co Ltd Improvement of current efficiency of cation exchange membranes
ZA774635B (en) * 1976-08-30 1978-06-28 Akzona Inc Microporous products and methods for making same
US4155781A (en) * 1976-09-03 1979-05-22 Siemens Aktiengesellschaft Method of manufacturing solar cells, utilizing single-crystal whisker growth
US4252843A (en) * 1977-02-18 1981-02-24 Minnesota Mining And Manufacturing Company Process for forming a microstructured transmission and reflectance modifying coating
US4209008A (en) * 1977-07-26 1980-06-24 United Technologies Corporation Photon absorbing surfaces and methods for producing the same
FR2427296A1 (en) * 1978-04-28 1979-12-28 Rikagaku Kenkyusho CATALYST FOR CONCENTRATING HYDROGEN ISOTOPES AND PROCESS FOR THE PRODUCTION OF A SUPPORT FOR THIS CATALYST
US4252865A (en) * 1978-05-24 1981-02-24 National Patent Development Corporation Highly solar-energy absorbing device and method of making the same
US4340276A (en) * 1978-11-01 1982-07-20 Minnesota Mining And Manufacturing Company Method of producing a microstructured surface and the article produced thereby
US4215183A (en) * 1979-01-02 1980-07-29 General Electric Company Wet proofed conductive current collector for the electrochemical cells
JPS602394B2 (en) * 1979-10-30 1985-01-21 工業技術院長 Method for manufacturing ion exchange membrane-catalyst metal assembly
US4550123A (en) * 1979-12-28 1985-10-29 Albany International Corp. Thermally plastifiable compositions for microporous sorbent structure
US4272353A (en) * 1980-02-29 1981-06-09 General Electric Company Method of making solid polymer electrolyte catalytic electrodes and electrodes made thereby
JPS6046515B2 (en) * 1980-09-27 1985-10-16 株式会社東芝 Method for manufacturing electrolyte retention matrix for fuel cells
US4396643A (en) * 1981-06-29 1983-08-02 Minnesota Mining And Manufacturing Company Radiation absorbing surfaces
JPS58169873A (en) * 1982-03-31 1983-10-06 Hitachi Ltd Selectively permeable film and its manufacture and liquid fuel cell using said film
JPS58201823A (en) * 1982-05-18 1983-11-24 Asahi Glass Co Ltd Preparation of ion exchange memerane
US4539256A (en) * 1982-09-09 1985-09-03 Minnesota Mining And Manufacturing Co. Microporous sheet material, method of making and articles made therewith
US4557957A (en) * 1983-03-18 1985-12-10 W. L. Gore & Associates, Inc. Microporous metal-plated polytetrafluoroethylene articles and method of manufacture
US4720400A (en) * 1983-03-18 1988-01-19 W. L. Gore & Associates, Inc. Microporous metal-plated polytetrafluoroethylene articles and method of manufacture
JPS60825A (en) * 1983-06-20 1985-01-05 Res Dev Corp Of Japan Manufacture of fine particles
US4568598A (en) * 1984-10-30 1986-02-04 Minnesota Mining And Manufacturing Company Article with reduced friction polymer sheet support
DE3672589D1 (en) * 1985-12-09 1990-08-16 Dow Chemical Co METHOD FOR PRODUCING A SOLID POLYMER ELECTROLYTE ELECTRODE WITH A LIQUID OR WITH A SOLVENT.
US4826554A (en) * 1985-12-09 1989-05-02 The Dow Chemical Company Method for making an improved solid polymer electrolyte electrode using a binder
DE3672975D1 (en) * 1985-12-09 1990-08-30 Dow Chemical Co SOLID POLYMER ELECTROLYTE ELECTRODE.
US4654281A (en) * 1986-03-24 1987-03-31 W. R. Grace & Co. Composite cathodic electrode
US4735875A (en) * 1986-03-24 1988-04-05 W. R. Grace & Co. Cathodic electrode
US4853305A (en) * 1986-03-24 1989-08-01 W. R. Grace & Co.-Conn. Cathodic electrode
US5143805A (en) * 1986-03-24 1992-09-01 W. R. Grace & Co.-Conn: Cathodic electrode
US4731310A (en) * 1986-08-15 1988-03-15 W. R. Grace & Co. Cathodic electrode
US4992126A (en) * 1986-08-08 1991-02-12 The Dow Chemical Company Method for making a current collector bonded to a solid polymer membrane
US4791037A (en) * 1986-08-15 1988-12-13 W. R. Grace & Co.-Conn. Carbon electrode
US5039561A (en) * 1986-08-25 1991-08-13 Minnesota Mining And Manufacturing Company Method for preparing an article having surface layer of uniformly oriented, crystalline, organic microstructures
US4812352A (en) * 1986-08-25 1989-03-14 Minnesota Mining And Manufacturing Company Article having surface layer of uniformly oriented, crystalline, organic microstructures
US4849311A (en) * 1986-09-24 1989-07-18 Toa Nenryo Kogyo Kabushiki Kaisha Immobilized electrolyte membrane
JPS63117321A (en) * 1986-11-04 1988-05-21 Riken Corp Production of perpendicular magnetic anisotropy film
US4726989A (en) * 1986-12-11 1988-02-23 Minnesota Mining And Manufacturing Microporous materials incorporating a nucleating agent and methods for making same
US4874567A (en) * 1987-04-24 1989-10-17 Millipore Corporation Microporous membranes from polypropylene
JPH0768377B2 (en) * 1987-07-20 1995-07-26 東燃株式会社 Electrolyte thin film
US4867881A (en) * 1987-09-14 1989-09-19 Minnesota Minning And Manufacturing Company Orientied microporous film
US5176786A (en) * 1988-07-13 1993-01-05 Minnesota Mining And Manufacturing Company Organic thin film controlled molecular epitaxy
US4863813A (en) * 1988-09-15 1989-09-05 Bell Communications Research, Inc. Primary source of electrical energy using a mixture of fuel and oxidizer
US4957943A (en) * 1988-10-14 1990-09-18 Minnesota Mining And Manufacturing Company Particle-filled microporous materials
US4910099A (en) * 1988-12-05 1990-03-20 The United States Of America As Represented By The United States Department Of Energy Preventing CO poisoning in fuel cells
US5120594A (en) * 1989-11-20 1992-06-09 Minnesota Mining And Manufacturing Company Microporous polyolefin shaped articles with patterned surface areas of different porosity
US5395705A (en) * 1990-08-31 1995-03-07 The Dow Chemical Company Electrochemical cell having an electrode containing a carbon fiber paper coated with catalytic metal particles
US5162167A (en) * 1990-09-11 1992-11-10 Allied-Signal Inc. Apparatus and method of fabricating a monolithic solid oxide fuel cell
US5138220A (en) * 1990-12-05 1992-08-11 Science Applications International Corporation Field emission cathode of bio-molecular or semiconductor-metal eutectic composite microstructures
US5238729A (en) * 1991-04-05 1993-08-24 Minnesota Mining And Manufacturing Company Sensors based on nanosstructured composite films
US5336558A (en) * 1991-06-24 1994-08-09 Minnesota Mining And Manufacturing Company Composite article comprising oriented microstructures
US5641565A (en) * 1991-07-05 1997-06-24 Asahi Kasei Kogyo Kabushiki Kaisha Separator for a battery using an organic electrolytic solution and method for preparing the same
JP3442408B2 (en) * 1991-07-24 2003-09-02 本田技研工業株式会社 Method for producing electrode-electrolyte assembly and fuel cell using the same
US5260360A (en) * 1991-10-18 1993-11-09 Minnesota Mining And Manufacturing Company Oil, water and sweat repellent microporous membrane materials
DE4140972A1 (en) * 1991-12-12 1993-06-17 Metallgesellschaft Ag MEMBRANE FOR A GAS DIFFUSION ELECTRODE, METHOD FOR PRODUCING THE MEMBRANE AND GAS DIFFUSION ELECTRODE WITH MEMBRANE
US5264299A (en) * 1991-12-26 1993-11-23 International Fuel Cells Corporation Proton exchange membrane fuel cell support plate and an assembly including the same
CA2070588A1 (en) * 1991-12-31 1993-07-01 Kimberly-Clark Worldwide, Inc. Conductive fabric and method of producing same
DE4208057C2 (en) * 1992-03-13 1993-12-23 Deutsche Aerospace Cell structure for electrolysers and fuel cells
US5272017A (en) * 1992-04-03 1993-12-21 General Motors Corporation Membrane-electrode assemblies for electrochemical cells
US5399184A (en) * 1992-05-01 1995-03-21 Chlorine Engineers Corp., Ltd. Method for fabricating gas diffusion electrode assembly for fuel cells
JPH0668157A (en) * 1992-05-04 1994-03-11 Internatl Business Mach Corp <Ibm> Apparatus and method for displaying information in database
JPH0676838A (en) * 1992-06-25 1994-03-18 Aqueous Res:Kk Ion exchange membrane fuel cell and its manufacture
JP2736840B2 (en) 1992-06-29 1998-04-02 兼松日産農林株式会社 Pneumatic fixture driving machine
JPH07147162A (en) * 1992-06-30 1995-06-06 Toyota Central Res & Dev Lab Inc Manufacture of jointed body of electrolytic film and electrode
US5277996A (en) * 1992-07-02 1994-01-11 Marchetti George A Fuel cell electrode and method for producing same
JPH0629032A (en) * 1992-07-08 1994-02-04 Sumitomo Electric Ind Ltd High polymer electrolyte film and its manufacture
JP3271801B2 (en) * 1992-09-22 2002-04-08 田中貴金属工業株式会社 Polymer solid electrolyte fuel cell, humidifying method of the fuel cell, and manufacturing method
DE4241150C1 (en) * 1992-12-07 1994-06-01 Fraunhofer Ges Forschung Electrode membrane composite, process for its production and its use
US5338430A (en) * 1992-12-23 1994-08-16 Minnesota Mining And Manufacturing Company Nanostructured electrode membranes
US5352651A (en) * 1992-12-23 1994-10-04 Minnesota Mining And Manufacturing Company Nanostructured imaging transfer element
US5460896A (en) * 1993-01-22 1995-10-24 Kabushiki Kaisha Equos Research Fuel cell
JPH06260183A (en) * 1993-03-04 1994-09-16 Sumitomo Electric Ind Ltd Diaphragm for aqueous solvent electrochemical device and battery with aqueous solvent using same
JPH06342667A (en) * 1993-03-23 1994-12-13 Asahi Chem Ind Co Ltd High molecular type fuel cell
US5635039A (en) * 1993-07-13 1997-06-03 Lynntech, Inc. Membrane with internal passages to permit fluid flow and an electrochemical cell containing the same
US5932185A (en) * 1993-08-23 1999-08-03 The Regents Of The University Of California Method for making thin carbon foam electrodes
US5429886A (en) * 1993-08-30 1995-07-04 Struthers; Ralph C. Hydrocarbon (hydrogen)/air aerogel catalyzed carbon electrode fuel cell system
US5834523A (en) * 1993-09-21 1998-11-10 Ballard Power Systems, Inc. Substituted α,β,β-trifluorostyrene-based composite membranes
US5514461A (en) * 1993-10-05 1996-05-07 Kureha Chemical Industry Co., Ltd. Vinylidene fluoride porous membrane and method of preparing the same
US5326619A (en) * 1993-10-28 1994-07-05 Minnesota Mining And Manufacturing Company Thermal transfer donor element comprising a substrate having a microstructured surface
GB9324101D0 (en) * 1993-11-23 1994-01-12 Johnson Matthey Plc Improved manufacture of electrodes
US5459016A (en) * 1993-12-16 1995-10-17 Minnesota Mining And Manufacturing Company Nanostructured thermal transfer donor element
US5659296A (en) * 1994-10-24 1997-08-19 Minnesota Mining And Manufacturing Company Exposure indicating apparatus
US5547551A (en) * 1995-03-15 1996-08-20 W. L. Gore & Associates, Inc. Ultra-thin integral composite membrane
US5599614A (en) * 1995-03-15 1997-02-04 W. L. Gore & Associates, Inc. Integral composite membrane
JP3555999B2 (en) * 1994-12-07 2004-08-18 ジャパンゴアテックス株式会社 Method for producing polymer solid electrolyte / electrode assembly for polymer electrolyte fuel cell
JP3481010B2 (en) * 1995-05-30 2003-12-22 ジャパンゴアテックス株式会社 Polymer solid electrolyte membrane / electrode integrated body and method for producing the same
US5620807A (en) * 1995-08-31 1997-04-15 The Dow Chemical Company Flow field assembly for electrochemical fuel cells
US5702755A (en) * 1995-11-06 1997-12-30 The Dow Chemical Company Process for preparing a membrane/electrode assembly
JPH09120827A (en) * 1995-10-24 1997-05-06 Mitsubishi Heavy Ind Ltd Solid polymer electrolyte fuel cell
US5879828A (en) * 1997-10-10 1999-03-09 Minnesota Mining And Manufacturing Company Membrane electrode assembly
US6136412A (en) * 1997-10-10 2000-10-24 3M Innovative Properties Company Microtextured catalyst transfer substrate
US6042959A (en) * 1997-10-10 2000-03-28 3M Innovative Properties Company Membrane electrode assembly and method of its manufacture
US6277512B1 (en) * 1999-06-18 2001-08-21 3M Innovative Properties Company Polymer electrolyte membranes from mixed dispersions

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