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WO2004114451A1 - Ensemble electrode a membrane etanche et a garniture - Google Patents

Ensemble electrode a membrane etanche et a garniture Download PDF

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Publication number
WO2004114451A1
WO2004114451A1 PCT/GB2004/002566 GB2004002566W WO2004114451A1 WO 2004114451 A1 WO2004114451 A1 WO 2004114451A1 GB 2004002566 W GB2004002566 W GB 2004002566W WO 2004114451 A1 WO2004114451 A1 WO 2004114451A1
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WO
WIPO (PCT)
Prior art keywords
gas diffusion
membrane
edges
electrode assembly
substrates
Prior art date
Application number
PCT/GB2004/002566
Other languages
English (en)
Inventor
Christopher James Barnett
David Edward Barnwell
Silvain Buche
Adam John Hodgkinson
Peter Antony Trew
Original Assignee
Johnson Matthey Public Limted Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Johnson Matthey Public Limted Company filed Critical Johnson Matthey Public Limted Company
Publication of WO2004114451A1 publication Critical patent/WO2004114451A1/fr

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0271—Sealing or supporting means around electrodes, matrices or membranes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0271—Sealing or supporting means around electrodes, matrices or membranes
    • H01M8/0273—Sealing or supporting means around electrodes, matrices or membranes with sealing or supporting means in the form of a frame
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/1007—Fuel cells with solid electrolytes with both reactants being gaseous or vaporised
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0271—Sealing or supporting means around electrodes, matrices or membranes
    • H01M8/028—Sealing means characterised by their material
    • H01M8/0284—Organic resins; Organic polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
    • H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
    • H01M8/242—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes comprising framed electrodes or intermediary frame-like gaskets
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to a membrane electrode assembly suitable for use in a polymer electrolyte membrane fuel cell wherein the membrane electrode assembly comprises an integrated seal and gasket.
  • a fuel cell is an electrochemical cell comprising two electrodes separated by an electrolyte.
  • a fuel e.g. hydrogen or methanol
  • an oxidant e.g. oxygen or air
  • Electrochemical reactions occur at the electrodes, and the chemical energy of the fuel and the oxidant is converted to electrical energy and heat.
  • Fuel cells are a clean and efficient power source, and may replace traditional power sources such as the internal combustion engine in both stationary and automotive power applications.
  • the electrolyte is a solid polymer membrane which is electronically insulating but ionically-conducting.
  • Proton- conducting membranes based on perfluorosulphonic acid materials are typically used, and protons, produced at the anode, are transported across the membrane to the cathode, where they combine with oxygen to create water.
  • MEA membrane electrode assembly
  • the principle component of a polymer electrolyte fuel cell is known as a membrane electrode assembly (MEA) and is essentially composed of five layers.
  • the central layer is the polymer membrane.
  • an electrocatalyst layer containing an electrocatalyst, which is tailored for the different requirements at the anode and the cathode.
  • an electrocatalyst layer containing an electrocatalyst, which is tailored for the different requirements at the anode and the cathode.
  • a gas diffusion substrate adjacent to each electrocatalyst layer there is a gas diffusion substrate.
  • the gas diffusion substrate must allow the reactants to reach the electrocatalyst layer and must conduct the electric current that is generated by the electrochemical reactions. Therefore the substrate must be porous and electrically conducting.
  • the MEAs can be constructed by several methods.
  • the electrocatalyst layer may be applied to the gas diffusion substrate to form a gas diffusion electrode.
  • Two gas diffusion electrodes can be placed either side of a membrane and laminated together to form the five-layer MEA.
  • the electrocatalyst layer may be applied to both faces of the membrane to form a catalyst coated membrane.
  • gas diffusion substrates are applied to both faces of the catalyst coated membrane.
  • an MEA can be formed from a membrane coated on one side with an electrocatalyst layer, a gas diffusion substrate adjacent to that electrocatalyst layer, and a gas diffusion electrode on the other side of the membrane.
  • Field flow plates are used to separate the MEAs.
  • the plates perform several functions: supplying the reactants to the MEAs, removing products, providing electrical connections and providing physical support.
  • the field flow plates and MEAs in the stack are compressed together at pressures typically from 50 to 200psi absolute, using for example a bladder or piston system or a series of bolts located in stack end plates.
  • one of the stack end plates also contains the necessary ports to provide access and removal from the stack of the reactants, products and any associated humidification water.
  • Ports are also required to provide access to and removal of the stack coolant from the stack cooling plates which are needed to remove the excess heat generated within the MEAs. From the ports in the stack end plate the gases and fluids are transported through the stack to each field flow plate.
  • the porting design may either be internal to the MEA or external of the MEA.
  • Sealing and gasketing in the stack are used for the purpose of preventing such occurrences.
  • the term "sealing” is used to denote a method of preventing fluid diffusion out of or through a single component.
  • the perimeter of a gas diffusion substrate can be sealed by impregnating the perimeter with a sealant material.
  • gasketing is used to denote a method of preventing fluid diffusion between components by placing a resilient material between the two components.
  • the membrane protrudes beyond the gas diffusion substrates by a considerable margin, e.g. by as much as 25mm, so that gaskets can be positioned between the protruding membrane and the field flow plates.
  • the gaskets are held in place by compression.
  • This method can be problematic, particularly with the very thin membranes (approximately 30 ⁇ m) that are increasingly being used, because the membrane is weak and may be damaged by the compressive forces. Additionally it is wasteful to use large amounts of expensive membrane material in regions outside the active area of the membrane electrode assembly.
  • WO 02/093669 discloses a method wherein gas diffusion substrates comprise gasket members on both planar faces.
  • the gasketed substrates may be catalysed and then combined with a membrane, or the gasketed substrates may be combined with a catalysed membrane.
  • a peripheral region of the membrane is sandwiched between the gasket members such that gas cannot diffuse between the two substrates.
  • gasket members must be applied to both of the gas diffusion substrates before formation of the MEA. It would be advantageous to have a method of sealing and gasketing the components in a fuel cell stack wherein a single integrated component can be applied after the formation of the MEA, and the single component meets all the sealing and gasketing requirements of the fuel cell stack.
  • EP 1 018 177 describes a method of applying resilient seals to formed MEAs wherein the gas diffusion substrates and the membrane in the MEAs are coextensive.
  • the present inventors have found that it is advantageous to apply elastomeric material to MEAs wherein the membrane extends beyond at least one of the gas diffusion substrates. If membrane is exposed beyond the gas diffusion substrates, there can be direct adhesion between the membrane and the elastomeric material and better sealing can be achieved.
  • the present invention provides a sealed and gasketed membrane electrode assembly comprising a) a first gas diffusion substrate, having edges and first and second planar faces, wherein the first gas diffusion substrate has a central region and an edge region such that the edge region is adjacent to the edges; b) a second gas diffusion substrate, having edges and first and second planar faces, wherein the second gas diffusion substrate has a central region and an edge region such that the edge region is adjacent to the edges; c) a polymer electrolyte membrane, having edges and first and second planar faces, wherein the membrane is located between the first and second gas diffusion substrates such that the first planar face of the membrane faces the first planar face of the first gas diffusion substrate, the second planar face of the membrane faces the first planar face of the second gas diffusion substrate and the edges of the membrane extend beyond the edges of at least one of the first and second gas diffusion substrates; d) a first electrocatalyst layer, wherein the first electrocatalyst layer is located between the first planar face of the first gas diffusion substrate
  • the gas diffusion substrates may be any suitable gas diffusion substrates known to those skilled in the art.
  • Typical substrates include substrates based on carbon paper (eg Toray® paper available from Toray Industries, Japan), woven carbon cloths (eg Zoltek® PWB-3 available from Zoltek Corporation, USA) or non-woven carbon fibre webs (eg Optimat 203 available from Technical Fibre Products, UK).
  • the carbon substrate is typically modified with a particulate material either embedded within the substrate or coated onto the planar faces, or a combination of both.
  • the particulate material is typically a mixture of carbon black and a polymer such as polytetrafluoroethylene (PTFE).
  • PTFE polytetrafluoroethylene
  • the gas diffusion substrates are between 150 and 300 ⁇ m thick.
  • a layer of particulate material such as carbon black and PTFE on the first planar faces of the first and second gas diffusion substrates there is a layer of particulate material such as carbon black and PTFE on the first planar faces of the first and second gas diffusion substrates.
  • these layers are present on the entire first planar face, but they may only be present on the central regions or they may only be present on the edge regions.
  • the first and second gas diffusion substrates both have a central region and an edge region extending through the thickness of the substrates.
  • the edge region is adjacent to the edges of the gas diffusion substrates.
  • the edge region comprises a volume within the substrate wherein all the region is within a distance of less than 20mm from the edges, preferably all the region is within a distance of less than 16mm from the edges.
  • the planar faces of the gas diffusion substrates may be continuous so that the edges of the substrate are found only at the periphery of the substrates. Alternatively, the planar faces of the gas diffusion substrates may not be continuous and may comprise ports or holes. In this case, the substrates will have edges around the periphery of the substrate and also within the substrate at the ports. The edge region will encompass the volume within the substrate that is adjacent to the periphery of the substrate and the volume that is adjacent to the ports.
  • the first and second gas diffusion substrates have the same dimensions.
  • the central regions of the first and second gas diffusion substrates are the same size, and the edge regions of the first and second gas diffusion substrates are the same size.
  • the polymer electrolyte membrane may be any type of ion-conducting membrane known to those skilled in the art.
  • the membrane is proton-conducting.
  • the membranes are often based on perfluorinated sulphonic acid materials such as National® (DuPont), Flemion® (Asahi Glass) and Aciplex® (Asahi Kasei).
  • the membrane may be a composite membrane, containing the proton-conducting material and other materials that confer properties such as mechanical strength.
  • the membrane may comprise a proton-conducting membrane and a matrix of silica fibres, as described in EP 875 524.
  • the membrane is suitably less than lOO ⁇ m thick, preferably less than 50 ⁇ m thick.
  • the membrane is located between the first and second gas diffusion substrates so that each planar face of the membrane is adjacent to a planar face of the first or the second gas diffusion substrate.
  • the planar faces of the membrane may be continuous so that the edges of the membrane are found around only at the periphery of the membrane.
  • the planar faces of the membranes may not be continuous and may comprise ports or holes.
  • the membranes will have edges around the periphery of the substrate and also within the membrane at the ports.
  • the edges of the membrane extend beyond the edges of at least one of the first and second gas diffusion substrates.
  • the edges of the membrane extend beyond the edges of both the first and second gas diffusion substrates, so that protruding membrane is present at all the edges of the membrane electrode assembly.
  • the membrane extends beyond the edges of at least one of the gas diffusion substrates and preferably both by between 0.5mm and 5mm, suitably between 0.5mm and 3mm.
  • the present invention does not require that the membrane extends significantly beyond the membrane, e.g. by 25mm, as required by prior art methods that place gaskets between the membrane and the field flow plates. Therefore, the present invention does not waste significant amounts of expensive membrane material beyond the active area of the fuel cell.
  • the membrane extends beyond at least one of the gas diffusion substrates and the sealing region encapsulates the membrane. If the membrane did not extend beyond at least one gas diffusion substrate (e.g. if the components in the membrane electrode assembly were coextensive) then the contact between the membrane and the sealing region would be reduced and there would be a greater risk of gas leakage.
  • An additional advantage of the membrane extending beyond at least one gas diffusion substrate is that the risk of electrical shorting between the two gas diffusion substrates is reduced. If the membrane was coextensive with the two substrates, or inboard of the substrates, then there is an increased risk that stray fibres from opposing substrates can touch, leading to an electrical short.
  • the electrocatalyst layers comprise an electrocatalyst which may be a finely divided metal black, or may be a supported catalyst wherein small metal particles are dispersed on electrically conducting particulate carbon supports.
  • the electrocatalyst metal is suitably selected from
  • platinum group metals platinum, palladium, rhodium, ruthenium, iridium and osmium
  • a base metal or an alloy or mixture comprising one or more of these metals or their oxides.
  • the preferred electrocatalyst metal is platinum, which may be alloyed with other precious metals such as ruthenium, or base metals such as molybdenum or tungsten. If the electrocatalyst is a supported catalyst, the loading of metal particles on the carbon support material is suitably in the range 10-100wt%, preferably 15-60wt%.
  • the electrocatalyst layers suitably comprise other components, such as ion-conducting polymer, which is included to improve the ionic conductivity within the layer.
  • the layers can be formed on the gas diffusion substrates, or the layers can be formed on the membrane.
  • the layers are applied such that in the final membrane electrode assembly, the electrocatalyst layers are not present as layers on the edge regions of the gas diffusion substrates and are only present on all or part of the central regions. In a particular embodiment the electrocatalyst layers are present on the entire central region, so that the active area of the cell (wherein the electrochemical reactions take place) is maximised.
  • the electrocatalyst layers are only present on part of the central region such that there is a gap of at least 1mm between the edge of the central region and the edge of the electrocatalyst layer.
  • the electrocatalyst layers should not be present on the edge regions of the substrates because the sealing region extends over the edge regions of the substrates and therefore the edge regions are outside the active area of the MEA.
  • the electrocatalyst should not be outside the active area because this is a waste of expensive catalyst material and, moreover, if gaseous reactants can reach catalyst outside the active area there is a risk of heterogeneous gas phase reactions and resultant pin-holing of the membrane.
  • the elastomeric, electrically insulating, mold processable material is suitably a polymeric material chosen from a group including silicones, fluorosilicones, fiuoroelastomers (e.g. Viton), EPDM (ethylene propylene diene monomer) rubbers, thermoplastic elastomers (e.g. styrene-butadiene block copolymer) and liquid crystal polymer elastomers.
  • the material must be chemically resistant in a fuel cell environment and must tolerate typical temperatures in a PEM fuel cell (up to 120°C for MEAs using perfluorinated membranes and potentially higher for other membranes).
  • the material is rapidly heat curable such that it can be employed in molding processes.
  • the material should cure in less than 10 minutes at 120°C or below, most preferably the material should cure in seconds at 90°C or below.
  • the viscosity of the material under molding conditions is suitably 2 to 200Pa.s., preferably 40 to 140Pa.s.
  • the elastomeric material must encapsulate the edges of the first gas diffusion substrate and the second gas diffusion substrate so that there cannot be fluid leakage through the edges of the substrates.
  • the elastomeric material must encapsulate the edges of the polymer electrolyte membrane so that there is no route for fluid leakage along the interface of the sealing region and the membrane, and so that a single region of elastomeric material can seal the edges of both gas diffusion substrates.
  • the elastomeric material must be present as a layer on the edge region of the second planar face of each of the first and second gas diffusion substrates to prevent fluid egress through these edge regions.
  • the elastomeric material is not present as a layer on any of the central region of the second planar face of each of the first and second gas diffusion substrates.
  • the elastomeric material will probably impregnate the edge region of the gas diffusion substrate to a certain extent, and this will facilitate mechanical keying between the elastomeric material and the substrate. It is possible, but not necessary, that the elastomeric material will impregnate the entire thickness of the edge region of the gas diffusion substrate.
  • the elastomeric material impregnates the entire edge region, it does not form a layer on the first planar face of the gas diffusion substrate.
  • the elastomeric material does not impregnate any of the central region of the gas diffusion substrate because any part of the gas diffusion substrate that is impregnated with elastomeric material cannot take part in fuel cell reactions and will be outside the active area of the membrane electrode assembly. Electrocatalyst is present next to some or all of the central region and it is undesirable for electrocatalyst to be outside the active area.
  • the elastomeric material is not present as a layer on the first planar faces of each of the first and second gas diffusion substrates so that the elastomeric material can be applied to a formed MEA.
  • the elastomeric material forms one or more gasketing members suitably in the form of ribs or ridges. It is advantageous that the elastomeric material has, the combined functions of sealing the edge of gas diffusion substrates and providing one or more gasketing members.
  • the sealing and gasketing features of the membrane electrode assembly can be applied using a single material in a single step 1 .
  • the gasketing members will ultimately be positioned adjacent to a co-operating field flow plate when the MEA is in a fuel cell stack.
  • the gasketing members are compressible under fuel cell loads, and are compressed against the field flow plates so that gas cannot escape between the substrates and the plates.
  • the gasketing member may compress against a flat portion of the field flow plate or may locate into a channel.
  • the gasketing members may be present on one or both faces of the MEA, depending on the design of the field flow plates.
  • the gasketing members may be located around the entire periphery of the MEA, or they may be located only in specific regions, e.g. along two sides of the MEA only.
  • the gasketing members usually run parallel to the edges of the MEA, but they may also comprise cross-pieces wherein regions of the gasketing member are perpendicular to the edge of the MEA.
  • the one or more gasketing members are located such that they will be ultimately be compressed between a field flow plate and the membrane. Compression of the gasket in this position provides mechanical sealing at the membrane edge and ensures effective sealing.
  • the one or more gasketing members are located such that they will ultimately be compressed between a field flow plate and a gas diffusion substrate. The advantage of having the gasketing members in this position is that it is easier to form gasketing members that are located on the substrates (as opposed to on the exposed membrane) because this region of the MEA is more rigid.
  • the gasketing members may have any shape suitable for compressing against a field flow plate. This includes ribs or ridges with conical or round cross-sections.
  • the height of the gasketing member above the first or second gas diffusion substrate is suitably between 0.25-5mm, preferably between 0.5- 1.5mm.
  • there is more than one gasket member so that if one gasket member fails, there is still adequate gasketing between the substrate and the plate.
  • the shape and number of the gasketing members will depend on the required degree of compression in the fuel cell stack and the load that can be applied.
  • the elastomeric material extends beyond the edge of the MEA and provides gasketing means for the ports of the field flow plates. It is known in the art to extend the membrane beyond the edge of the gas diffusion substrates and to place gaskets on the surface of the membrane. Therefore, at external ports in known fuel cell stacks, the field flow plate would contact a gasket which was located on a membrane. On the other side of the membrane there would be another gasket which would contact the second field flow plate. Extending the membrane in this manner is a waste of expensive ion-conducting membrane material. In this embodiment of the present invention, the membrane does not extend as far as the external ports, and only the elastomeric material is present adjacent to the external ports. Therefore, at an external port the field flow plate contacts the elastomeric material, which contacts another field flow plate.
  • a first process is injection molding wherein the MEA is placed in a preheated mold, having an inlet and a vent. The MEA is clamped in the mold at a pressure that will not damage the MEA.
  • the temperature in the mold should not be so high that it presents a risk of drying out the membrane or damaging the electrocatalyst layers. For commonly used perfluorosulphonic membranes, the temperature should not be above 100°C.
  • the elastomeric, electrically insulating, mold processable material is injected through the inlet under pressure. The material will start to cure in the mold, but the MEA can be taken out of the mold before curing is complete.
  • a second process is compression molding.
  • the elastomeric material is applied to the MEA using any suitable dispensing process and is then placed in a preheated mold, having a vent.
  • the MEA is clamped in the mold at a pressure that will not damage the MEA and a temperature that will not present a risk of drying out the membrane or damaging the electrocatalyst layers.
  • the mold is shaped such that the elastomeric material will encapsulate the edges of the gas diffusion substrates and the membrane, it will form a layer on the edge regions of the second planar faces of the gas diffusion substrates and it will form one or more gasketing members.
  • the pre-treatment comprises impregnating part or all of the edge regions of the first and second gas diffusion substrates and/or coating part or all of the protruding edge of the membrane with a primer material such as a silicone, fluorosilicone, EVA copolymer, EAA copolymer, fluorosilane or silane (this may or may not be the same material as the elastomeric material that is used to form the seal on the MEA). Impregnation of a primer material into part or all of the edge regions may help to reinforce the edge regions of the substrate.
  • a primer material such as a silicone, fluorosilicone, EVA copolymer, EAA copolymer, fluorosilane or silane
  • the pre-treatment may be carried out by any suitable process such as dip-coating, spraying, screen printing, robotic dispensing and pressing, or hot pressing.
  • the present invention provides an integrated cell assembly comprising an MEA according to the invention joined to a field flow plate.
  • the present invention provides a fuel cell comprising an MEA according to the invention.
  • Fig. 1 is a cross-sectional side view of one end of a sealed and gasketed MEA according to one embodiment of the invention.
  • Fig. 2 is a cross-sectional side view of one end of a sealed and gasketed MEA according to a further embodiment of the invention.
  • Fig. 3 is a cross-sectional side view of one end of a sealed and gasketed MEA according to a yet further embodiment of the invention.
  • Fig. 1 shows a portion of a membrane electrode assembly comprising a polymer electrolyte membrane (1) located between two gas diffusion substrates (2). The edge of the membrane (1) extends beyond the edges of the substrates (2). Electrocatalyst layers
  • the elastomeric material (4) is present on a region of the outside faces of the gas diffusion substrates (2) and envelops the edges of the membrane (1) and the substrates (2).
  • the elastomeric material does not impregnate the substrates (2).
  • the elastomeric material (4) only covers an edge region of the substrates (2) and the electrocatalyst material (3) is not present as a layer on this edge region, but does cover the entire central region.
  • the elastomeric material (4) forms several gasketing members (5).
  • the gasketing members (5) are located such that they will ultimately be compressed between a field flow plate and the membrane (1), i.e. they are located above and below the protruding portion of the membrane.
  • Fig. 2 shows a portion of a membrane electrode assembly comprising a polymer electrolyte membrane (1) located between two gas diffusion substrates (2). The edge of the membrane (1) extends beyond the edges of the substrates (2). Electrocatalyst layers
  • the gasketing members (5) are located such that they will ultimately be compressed between a field flow plate and a gas diffusion substrate, i.e. they are located above and below the substrates (2).
  • Fig. 3 shows a portion of a membrane electrode assembly comprising a polymer electrolyte membrane (1) located between two gas diffusion substrates (2). The edge of the membrane (1) extends beyond the edges of the substrates (2). Electrocatalyst layers
  • the elastomeric material (4) is present on a region of the outside faces of the gas diffusion substrates (2) and envelops the edges of the membrane (1) and the substrates (2).
  • the MEA has been preheated before the elastomeric material (4) was applied, by impregnating a primer material (6) into part of the edge regions of the substrates (2).
  • the elastomeric material (4) forms several gasketing members (5).
  • a state-of-the-art MEA was prepared from two 200 ⁇ m Toray® TGP-H-060 gas diffusion substrates (each with a carbon black/PTFE base layer across one entire face) and a 30 ⁇ m Flemion® SH-30 membrane.
  • Catalyst layers comprising carbon-supported Platinum catalysts and Flemion® ionomer were applied to the two substrates, on top of the base layer.
  • the catalysed substrates and the membrane were combined in a lamination process.
  • the two substrates had the same dimensions and the membrane extended beyond the edge of the substrates by 1mm.
  • the catalyst layers were not present on the entire face of the substrates; there was a margin around the periphery of the substrates that was not coated with catalyst.
  • Silicone rubber was applied at various points around the periphery of the MEA using a pressurised syringe.
  • the MEA was placed into a mold and heated to 92°C for 5 minutes at up to 250psi.
  • the MEA was removed from the mold and allowed to cool.
  • the mold was shaped such that the silicone rubber formed a layer on edge regions of the two substrates that is within 12.5mm of the edge of the substrates.
  • the thickness of the layer was approximately 20-3 O ⁇ m.
  • the silicone rubber encapsulated the edges of the substrates and the membrane and extended 1.5mm beyond the edge of the membrane.
  • the mold also formed the silicone rubber into several gasketing members, positioned above the substrate.
  • the MEA with the integrated seal and gasket was sandwiched between two field flow plates and placed in a fuel cell. It was operated for more than 300 hours. No leakage was observed after testing and no damage was evident when the MEA was removed from the cell.
  • a state-of-the-art MEA was prepared as described in Example 1.
  • a mask was placed over the MEA, covering the active area.
  • Silicone adhesive was dispensed around the perimeter of the MEA. The adhesive was pressed into the edge region of the substrates and was cured at 90°C for 10 minutes. This pre-treatment step provided an MEA wherein the edge regions of the substrates were impregnated with silicone.
  • silicone rubber was applied as for Example 1, and was molded as described in Example 1.
  • the silicone rubber encapsulated the edges of the substrates and the membrane and extended 1.5mm beyond the edge of the membrane.
  • the mold also formed the silicone rubber into several gasketing members, positioned above the substrate.
  • the MEA was sandwiched between two field flow plates and placed in a fuel cell. It was operated for more than 300 hours. No leakage was observed after testing and no damage was evident when the MEA was removed from the cell.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
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  • Sustainable Energy (AREA)
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Abstract

L'invention concerne un ensemble électrode à membrane étanche et à garniture comprenant un premier et un second substrats diffuseurs de gaz, une membrane électrolytique polymère, une première et une seconde couches électrocatalytiques et un matériau élastomère, isolant électrique et pouvant être traité à l'état fondu qui encapsule les bords du premier, du second substrats de diffusion de gaz, et la membrane électrolytique polymère et forme en outre au moins un élément de garniture.
PCT/GB2004/002566 2003-06-20 2004-06-14 Ensemble electrode a membrane etanche et a garniture WO2004114451A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0314436.7 2003-06-20
GBGB0314436.7A GB0314436D0 (en) 2003-06-20 2003-06-20 Membrane electrode assembly

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WO2004114451A1 true WO2004114451A1 (fr) 2004-12-29

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Cited By (12)

* Cited by examiner, † Cited by third party
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EP1693915A1 (fr) * 2005-02-18 2006-08-23 Carl Freudenberg KG Structure de joint pour pile à combustible
WO2007090423A1 (fr) * 2006-02-09 2007-08-16 Carl Freudenberg Kg Unité de diffusion de gaz
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US7368200B2 (en) 2005-12-30 2008-05-06 Tekion, Inc. Composite polymer electrolyte membranes and electrode assemblies for reducing fuel crossover in direct liquid feed fuel cells
WO2008086841A1 (fr) * 2007-01-16 2008-07-24 Carl Freudenberg Kg Dispositif d'étanchéité pour élément de plaque d'une pile à combustible
WO2008146134A1 (fr) * 2007-05-28 2008-12-04 Toyota Jidosha Kabushiki Kaisha Pile à combustible
WO2009149907A1 (fr) * 2008-06-13 2009-12-17 Carl Freudenberg Kg Agencement pour une pile à combustible
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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1693915A1 (fr) * 2005-02-18 2006-08-23 Carl Freudenberg KG Structure de joint pour pile à combustible
US7368200B2 (en) 2005-12-30 2008-05-06 Tekion, Inc. Composite polymer electrolyte membranes and electrode assemblies for reducing fuel crossover in direct liquid feed fuel cells
WO2007090423A1 (fr) * 2006-02-09 2007-08-16 Carl Freudenberg Kg Unité de diffusion de gaz
US8383285B2 (en) 2006-02-09 2013-02-26 Carl Freudenberg Kg Gas diffusion unit
KR100979605B1 (ko) 2006-02-09 2010-09-01 칼 프로이덴베르크 카게 가스 확산 유닛
WO2008000719A1 (fr) * 2006-06-29 2008-01-03 Solvay Solexis S.P.A. Ensembles destinés à des dispositifs électrochimiques
JP2009541964A (ja) * 2006-06-29 2009-11-26 ソルヴェイ ソレクシス エス．ピー．エー． 電気化学デバイス用の集合体
WO2008000724A1 (fr) * 2006-06-29 2008-01-03 Solvay Solexis S.P.A. ensembles pour dispositifs électrochimiques
WO2008000718A1 (fr) * 2006-06-29 2008-01-03 Solvay Solexis S.P.A. Ensembles destinés à des dispositifs électrochimiques
US9190687B2 (en) 2006-06-29 2015-11-17 Solvay Solexis S.P.A. Assemblies for electrochemical devices
WO2008086841A1 (fr) * 2007-01-16 2008-07-24 Carl Freudenberg Kg Dispositif d'étanchéité pour élément de plaque d'une pile à combustible
WO2008146134A1 (fr) * 2007-05-28 2008-12-04 Toyota Jidosha Kabushiki Kaisha Pile à combustible
WO2009149907A1 (fr) * 2008-06-13 2009-12-17 Carl Freudenberg Kg Agencement pour une pile à combustible
WO2012017225A1 (fr) * 2010-08-03 2012-02-09 Johnson Matthey Plc Structure de membrane
CN103119771A (zh) * 2010-08-03 2013-05-22 庄信万丰燃料电池有限公司 膜结构
US9692071B2 (en) 2010-08-03 2017-06-27 Johnson Matthey Fuel Cells Limited Membrane structure
DE102013004473A1 (de) 2013-03-14 2014-09-18 Volkswagen Aktiengesellschaft Verfahren zum Herstellen einer Membran-Elektroden-Anordnung sowie Schutzvorrichtung zur Durchführung des Verfahrens
US20220271325A1 (en) * 2021-02-22 2022-08-25 Advanced Battery Concepts, LLC Battery assembly membrane application

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