FR2961349A1 - Electrode for fuel cell used in electrically powered cars comprises current collector, intrinsically electron-conducting adhesive, electrocatalyst that is bonded to current collector, and ionomer layer in contact to electrocatalyst - Google Patents

Abstract

An electrode comprises a current collector (200); an intrinsically electron-conducting adhesive (202) on a surface of the current collector; an electrocatalyst (204) that is bonded to the current collector by the electron-conducting adhesive; and an ionomer layer in contact to the electrocatalyst. Independent claims are included for: (1) an intrinsically electron-conducting adhesive for bonding electrocatalysts comprising intrinsically electron-conducting polymer(s), dopant(s), and tackifier(s); and (2) a fuel cell comprising an anode, an electrolyte and a cathode comprising a current collector; an electron-conducting adhesive on a surface of the current collector; an electrocatalyst that is bonded to the current collector by the electron-conducting adhesive; and an ionomer layer (210) in contact to the electrocatalyst.

Description

Title: Fuel Cell Cathode and Fuel Cell by Friedrich W. Wieland FIELD OF THE INVENTION This invention relates to cathodes for fuel cells.

BACKGROUND Fuel cells and half fuel cells, or "semi-fuel cells", which use hydrogen peroxide or oxygen as the oxidant are environmentally friendly methods for generating electricity. Quite large quantities of very expensive catalysts such as platinum and platinum alloys must be used in order to reach the necessary current densities for a fuel cell car because the use of catalyst is quite low (about 9% for PEM fuel cells). An estimate of the production costs of fuel cell electrodes for a fuel cell car was $ 50-100 (US dollars) per kilowatt according to S. Srinivasan ("Fuel Cells", Springer, 2006, p. 603). Costs-manufacturing a fuel cell car with the performance of traditional cars (80 kW) of $ 4000 - $ 8000 (US dollars) are provided only for electrodes. Prior art electrodes for polymer electrolyte membrane (PEM) fuel cells are produced by a coating process an ink containing a catalyst and a dispersion of a perfluorinated polymer which is an ionomer such as copolymers of tetrafluoroethylene and perfluorovinyl ether sulfonic acid manufactured and sold by EI DuPont of Nemours and Co., Wilmington, Delaware, USA under the trademark "Nafion". Such an electrode is shown in FIG. 1. The supported catalyst (104) with platinum, palladium or iridium electrocatalyst centers (106) is accidentally dispensed into the catalyst and ionomer layer (102) formed from the on a current collector (100). So far, despite huge efforts of research for decades, chemists have not discovered the disadvantages that result from this random electrode structure. "NAFION" is an ionic conductor that does not conduct electrons. But in order to operate as an electrocatalyst a catalyst particle must take electrons from the cathode current collector as indicated by the arrows in Figure 1 illustrating the flow of electrons into the cathode. Thus the use of the catalyst is reduced by the random dispersion of catalyst in an electrically insulating polymer because only the fraction of the catalyst which is in electrical contact with the current collector acts as the electrocatalyst for the production of electrical energy (see Figure 1). Information regarding efforts to address these problems can be found in United States Patent Applications Number US2008 / 0182153 A1, US2008 / 0193827 A1, US2008 / 0063922 A1, US2008 / 0054226 A1, US2004 / 0224218 A1, US2004. / 0191605, United States Patent Numbers US7175930, US5296429, US5445905, US6465124 and Electrochemistry Communications Articles 10 (2008), 1610, in press, Journal of Power Sources 165 (2007), 509 and Journal of Power Sources 164 (2007). ), 441.

But each of these references suffers from one or more of the following disadvantages by long diffusion paths for reagents (oxidants H2O2 or O2 and H30 +) and products (H2O) from the electrolyte to the electrocatalyst and vice versa, by high production costs due to complicated manufacturing processes and low catalyst efficiency due to the lack of a conduction path for electrons.

For the foregoing reasons, there is a need for hydrogen peroxide cathodes and oxygen cathodes for fuel cells which are more efficient, cheaper to manufacture and durable and which can produce more current densities. with a lower polarization and which can be exploited in concentrated solutions of hydrogen peroxide.

SUMMARY The present invention relates to these cathode requirements of a fuel cell. The cathodes of a fuel cell according to the invention comprise an electrode structure which has an optimized topology not only for the transport of the reactants and products of the cathode reaction (1) or (2), but also for the electron transport of the cathodic reaction. A fuel cell cathode according to one embodiment of the invention comprises an electrocatalyst which is bonded to the current collector using an adhesive which is a. intrinsic conductor for electrons. This increases the number of catalyst particles in the electrocatalyst layer that are electrically connected to the current collector by a conductive adhesive. Thus the use of catalyst is greater than in prior art electrodes employing the accidental distribution of catalyst particles in a polymer that does not conduct electrons. The catalyst layer is covered by an ion conductive layer of an ionomer such as copolymers of tetrafluoroethylene and perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid manufactured and sold by EI DuPont de Nemours and Co., Wilmington, Delaware, USA, under the trademark "Nafion". This thin layer of an ionomer ensures the efficient transport of the products (water) and reactants of the cathodic reaction such as oxidants H2O2 or 02 and H3O + by diffusion. The ionomer layer also protects the catalyst layer against abrasion and improves the durability of the cathode and a good wetting of the catalyst layer by the electrolyte. This topology ensures optimal electronic and ionic conductivity as well as optimum transport of oxidant and water. The catalyst may be a supported electrocatalyst (such as platinum on carbon) or an unsupported catalyst (such as platinum black) and consists of no platinum family metal, no transition metal, bismuth, tin or aluminum or its alloys. Preferred electrocatalyst for cathodes of hydrogen peroxide includes ruthenium and its alloys. Ruthenium alloys (with <10 mol%) of two other metals of the platinum family or rhenium are the most preferred.

The preferred conductive adhesive comprises an intrinsic electronic conductive polymer such as polyaniline and a dopant. According to one embodiment of the invention an ionomer such as "NAFION" may be used as the dopant. According to one embodiment of the invention the electronic conductive adhesive comprises an intrinsic electronic conductive polymer such as polyaniline, a fluorinated ionomer such as "NAFION" and a solvent such as dimethylsulfoxide, dimethylformamide or N-methylpyrrolidone. According to one embodiment of the invention an electronic conductive adhesive which is a pressure sensitive adhesive (PSA) and which also comprises an elastomer and a tackifier resin (in English, "tackifier"). ) is preferred.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages of the present invention will be apparent from the description, the claims and the accompanying drawings, in which: FIG. 1 shows a sectional view of a portion of an electrode of a prior art fuel cell with the electron flow of the current collector for the active catalyst particles as the electrocatalyst;

Figure 2A shows a sectional view of a portion of a hydrogen peroxide cathode according to one embodiment of the present invention; Figure 2B shows a sectional view of a particle of an electrocatalyst supported with metal centers (a ruthenium alloy for hydrogen peroxide cathodes); Fig. 2C shows a sectional view of a portion of a hydrogen peroxide cathode with the electrocatalyst without support according to another embodiment of the present invention; Fig. 2D shows a sectional view of a particle without an electrocatalyst support of metal black; Figure 3A shows a sectional view of a cathode of oxygen according to another embodiment of the present invention; Fig. 3B shows a sectional view of a carbon fiber coated with the cathode of oxygen shown in Fig. 3A; FIG. 3C shows a sectional view of a carbon fiber bundle coated according to an alternative embodiment of the oxygen cathode; Fig. 3D shows an oxygen cathode of Fig. 3A comprising coated carbon fibers which are shown in Fig. 3C and which are attached to a polymer electrolyte membrane (PEM) of a polymer electrolyte membrane fuel cell; Figure 3E shows a larger portion of a coated carbon fiber cathode of Figure 3A; Figure 4A shows a portion of a porous body which is conductive coated with an electrocatalyst of an oxygen cathode according to another embodiment of the present invention; Figure 4B shows two pores of a porous body which is conductive coated with an electrocatalyst of an oxygen cathode of Figure 4A; Figure 4C shows a side view of the pores of Figure 4B; Figure 4D shows a cross-section through the pores of Figure 4C; Fig. 5 shows a fuel cell according to one embodiment of the present invention; FIG. 6 shows a sectional view of a bipolar electrode comprising a cathode according to the present invention and an anode; and Fig. 7 shows a sectional view of a membrane electrode assembly (EME) comprising a cathode according to the present invention, a polymer electrolyte membrane and an anode. These and other features, aspects and advantages of the invention will be apparent from the following description and the appended claims.

DETAILED DESCRIPTION

A cathode according to one embodiment of the present invention comprises according to Figure 2A a current collector (200) coated with a layer of an adhesive (202) which conducts electrons. The adhesive (202) adheres particles of the electrocatalyst (204, see Figure 2B) to the current collector. This ensures a good electrical contact of the electrocatalyst to the current collector which is necessary in order to increase the use of the electrocatalyst. The adhesive can be applied by screen printing, painting or other techniques used to apply an adhesive.

As the electrocatalyst a supported catalyst such as platinum family metals (206) on carbon (208) or a catalyst such as platinum black without support can be used. The cathode comprises a coating of an ion conductor (210) on the catalyst particles that consists of an ionomer. This coating provides good ionic conductivity at the surface of the catalyst particles and a good wetting of the cathode by the electrolyte. It also ensures the efficient transport of the cathodic reaction educts such as H2O2 or O2 and H3O + ions to the electrocatalyst and the transport of the product (water) from the electrocatalyst to the electrolyte. The coating of an ionomer also increases the durability of the cathodes because it is a polymer coating that enhances catalyst particles in the catalyst layer. The topology of a cathode according to an embodiment of the invention according to the indications of FIG. 2A thus optimizes this conductivity (electronic and ionic) and reduces the diffusion problems that arise in art fuel cell cathodes. prior. This topology also increases the use of the catalyst because more catalyst particles are electrically connected to the current collector which reduces the charge rate and catalyst costs. In addition, it allows the use of a supported electrocatalysts or black metal with a large area that reduces cathodic polarization. As the conductive adhesive (202) an adhesive is preferable which comprises an intrinsic electronic conductive polymer. This is advantageous over conventional conductive adhesives which contain graphite or silver particles which have a diameter similar to or larger than the diameter of the electrocatalyst particles (204). A conductive adhesive that conducts electrons intrinsically can provide electrical contact to the very small catalyst particles that are much smaller than the particles of the graphite or silver conductive additives of conventional conductive adhesives incorporated in a nonconductive matrix. Thus the inherently conducting conductive adhesive provides electrical contact of a larger number of the electrocatalyst particles (204) to the current collector (200) because a very small adhesive bridge can provide an electrical connection to the collector of the electrocatalyst (204). current (see Figure 2) that would behave non-conductive polymer in conventional conductive adhesives with graphite or silver. As the intrinsic conductive polymer of the conductive adhesive (202) a large number of polymers are suitable. Polyaniline (PANI) is a preferred intrinsic conductive polymer because polyaniline is cheaper and generally obtainable from several manufacturers such as Ormecon Chemie GmbH & Co. KG, D-22941 Ammersbeck, Germany. In addition polyaniline is stable in electrolytes that contain strong oxidants such as hydrogen peroxide and it provides excellent conductivity. Nevertheless a large number of aniline copolymers with aniline derivatives such as anthranilic acid or other monomers conduct polymers such as thiophene, pyrrole, furan, and many other polymers intrinsically such as polythiophenes, for example poly (3,4-ethylenedioxythiophene) (PEDOT), polypyrroles, polyfurans, polyparaphenylenes, polyazulenes, polyindoles, polypyridines, polypyrazines, polytriazines, polythiazoles, polyimidazoles polyquinolines, polybenzimidazoles, polytriazoles, polyoxydiazoles, polycarbazoles, polybenzothiophenes, polybenzofurans, polyheptadiyne, and poly (para-phenylenes-vinylenes) and their substituted and copolymeric derivatives may also be intrinsically suitable polymers of conduct. for the pipe adhesive (202). The adhesive (202) may also include a dopant if the polymer is not self-doped such as the copolymers of aniline and anthranilic acid. Alternatively, doped conductive polymers (e.g., emeraldine salts PANI) can be used. As acidic Bronsted dopants such as hydrochloric acid, sulfuric acid, perchloric acid, as well as carboxylic acids or sulfonic acids, such as methanesulfonic acid, p-toluene sulfonic acid, dodecylbenzene sulfonic acid (DBSA), naphthalene dinonyl sulfonic acid, camphorsulfonic acid (CSA), or polymeric acids such as poly (styrenesulfonic acid), for example in PEDOT: PSS, manufactured and sold by HC Stark, GmbH, D-38642 Goslar, Germany, under the trademark "CLEVIOS P", may be used. In fact conventional dopants ionomers that have acidic groups, such as sulfonic acid groups can be used as dopants. Copolymers of tetrafluoroethylene and a perfluorovinyl ether sulfonic acid which are generally sold under the brand name "NAFION" by EI DuPont of Nemours and Company, Wilmington, Delaware, USA, are ionomers which are more preferred as dopants for intrinsic adhesive conduction (202). The adhesive may include a solvent for polyaniline (emeraldine base) such as dimethylsulfoxide (DMSO), dimethylformamide and N-methyl pyrrolidinone although other solvents may be suitable, too. More preferred are PANI and "NAFION" dispersions in DMSO compounds and alcohols (such as propanol) and water. Preferred are also PEDOT solutions: PSS and "NAFION" in alcohol / water as the electronically conductive adhesives that lead intrinsically (202). Intrinsically conductive electronic conductive adhesives which are a Pressure Sensitive Adhesive (PSA) are the most preferred conductive adhesives because they simplify cathode production. A polyanilinedopant complex such as PANI with dodecylbenzene sulfonic acid (PANI-DBSA) which is soluble in an organic solvent such as p-xylene, can be used for the production of a conductive glue which inherently leads to PSA type comprising in addition to an elastomer and a tackifying resin (in English, "tackifier") such as poly-a-pinene.

According to one embodiment of the present invention, the catalyst is coated with a thin ion conductive layer of an ionomer such as copolymers of tetrafluoroethylene and perfluorovinyl ether sulfonic acid manufactured and sold by EI DuPont of Nemours and Co., Wilmington. , Delaware, United States, under the trademark "Nation" or "FUMION" manufactured and sold by Fuma-Technologie GmbH, D-66386 St. Ingbert, Germany.

This ionomer acts as an ion conductive layer which provides ionic conduction contact of all catalyst particles to the electrochemical cell as well as the transport of oxidants (hydrogen peroxide or oxygen) and the product. of the water of the cathodic reaction. In addition, this ionomer polymer layer protects the catalyst layer against abrasion and a good wetting of the cathode by the electrolyte for cathodes of hydrogen peroxide.

Preferred is a coating employing a copolymer of tetrafluoroethylene and perfluorovinyl ether sulfonic acid manufactured and sold by EI DuPont of Nemours and Co., Wilmington, Delaware, USA, such as a 5% solution (equivalent weight of 1100 g / mol) in a compound of lower aliphatic alcohols and water or a dispersion of 5% "FUMION FLNA-905" (equivalent weight of 900 g / mol) in a compound of n-propanol (50%) and water (45%) , manufactured and sold by Fuma-Technologie GmbH, D-66386 St. Ingbert, Germany. According to another embodiment of the present invention, the topology of the oxygen cathodes shown in FIGS. 3A, 3B, 3C, 3D and 3E is adapted to the condition of the three-phase contact instead of two phases for cathodes of hydrogen peroxide. Fig. 3A shows a sectional view of an oxygen electrode according to an embodiment of the invention which consists of carbon-coated fibers (300) as a current collector. The carbon fibers (300) of the oxygen cathode shown in Figure 3B are coated with a catalyst layer on an inherently conducting conductive adhesive (302). The carbon fibers (300) are used as the current collectors. The single fibers (300) may be coated as shown in Figure 3B or carbon fiber bundles (312) or carbon fiber woven may be used as the current collectors as shown in Figure 3C . Figure 3D shows a sectional view of a carbon fiber electrode that can be used as the oxygen cathode for fuel cells. The coated carbon fibers (300) are mounted on a current collector substrate (312) such as a titanium current collector, a carbon paper or a carbon fiber compound with an electronically conductive polymer with an agent to attach the carbon fibers to this substrate (312) such as adhering with a conductive adhesive or seizing the ends of the carbon fibers in a support on a metal substrate. The resulting cathodes can be bonded to a PEM-membrane (314) of a PEM fuel cell with a "NAFION" coating as shown in Figure 3D. A cathode made of coated carbon fibers shown in Figure 3B or Figure 3C can also be used as the hydrogen peroxide cathode of a hydrogen peroxide fuel cell or a half fuel cell. , in English, "semi fuel cells".

As current collector material (300 in FIGS. 3A-3C) other materials which have a large area such as carbon fiber fabrics, metal fabrics, hollow-shaped carbon tubes, carbon porous such as carbon airgel or metal sponge such as titanium sponge may be used. The current collector material (300) is covered by an adhesive layer (302), a catalyst layer (306), and an ionomer coating (310) as shown in Figure 3A. Supported electrocatalysts (such as platinum, platinum alloys (306) or ruthenium on carbon (308)) or unsupported catalyst can be employed. For platinum alloy oxygen cathodes of the prior art can be used as the preferred electrocatalysts.

The catalyst particles (304, 306) are adhered to the carbon fibers (300) by a conductive adhesive (302) comprising the intrinsic conductive polymers. The catalyst layer is covered by a layer of a thin ionomer (310) which ensures rapid diffusion of oxygen. This layer (310) comprises a fluorinated ionomer such as "NAFION" or "FUMION". "NAFION" may also be used to bond the fibers to a PEM membrane (314) of a fuel cell as an adhesive bridge of an ionic conductor as shown in Figure 3D. The "NAFION" bridge may consist essentially of a porous "NAFION" foam produced by the appropriate additives in this ionomer, which produce a gas during drying or heating, such as azodicarboxamide, fluorinated hydrocarbons or compositions comprising an acid component and an alkali or alkali carbonate of the earth or an alkali hydrogen carbonate which produce carbon dioxide. The pores of the "NAFION" foam improve the diffusion of oxygen. The topology of this oxygen cathode according to the invention ensures rapid diffusion of oxygen and good ionic conductivity as well as good electrical conductivity.

In fact, carbon-fiber hollow tubes that are conductive can be used for an oxygen electrode according to an embodiment of the present invention. The electrocatalyst layer in the tubes can be glued inside these hollow tubes, which are conductive. This can be accomplished by immersing the tubes in a conductive glue of low viscosity and coating in the interior of the tubes with a fine powder of a catalyst by blowing with compressed air. After drying the tubes, the electrocatalyst layer may be coated with a thin layer of an ionomer which is an ion conductor such as "NAFION". Further, the electrocatalyst (207) adhered by the electronically conductive adhesive which intrinsically leads (202) to a current collector / gaseous diffusion layer (200) according to the present invention can be employed in the cathodes of the fuel cell. PEM type which uses a polymer electrolyte membrane (210), anode electrocatalyst layer (230) and a current collector / gaseous diffusion layer of anode (232) as shown in FIG. According to another embodiment of the present invention shown in Figs. 4A-4D a porous current collector (400) such as titanium sponge can be coated in the same way for use as an electrode. to oxygen. The substrate may be coated with the pipe adhesive (402) by immersion, the electrocatalyst layer (406) may be applied by blowing the catalyst powder onto the adhesive by compressed gas. The coating of an ionomeric layer such as "NAFION" (410) can be performed by immersion, again. The topology of this design provides better electrical conductivity of the glue that binds the catalyst as well as the rapid diffusion of oxygen and hydronium ions (H3O +). For fuel cells using hydrogen peroxide cathodes (500) as shown in Figure 5, the catholyte is separated from the anolyte of each cell by a polymer electrolyte membrane (PEM, 504). The catholyte and the oxidant are supplied by the tubes (506, 508), anolyte and fuel through the tubes (510). The cathodes (500) according to the present invention are mounted in an electrode holder consisting of two metal sheets (516, 518) and the screws (520). A metal bar (512, 514) provides electrical contact on the electrodes of each cell. Titanium is the preferred material for these brackets and screws for the cathode and metal bar. The electrodes may be arranged as bipolar electrodes as shown in FIG. 6 having a cathode (with a conductive substrate (200), a layer of a conductive adhesive that inherently (202) conducts, a catalyst layer (207) and an ionomer layer (210)) and an anode (220). The fuel cells using an oxygen cathode according to an embodiment of the present invention and an anode of a direct borohydride battery, an anode of a direct methanol fuel cell, an anode of a fuel cell using formaldehyde or formate can also use a fuel cell assembly shown in Figure 3D. The anode is covered by an electrocatalyst such as platinum-ruthenium bimetallic catalysts for methanol or any other organic fuels or palladium for borohydride. The anode is wetted by an anolyte which contains the corresponding fuel. A PEM membrane (314) separates the cathode and the anolyte. For a fuel cell using an active metal anode such as a magnesium anode, an aluminum anode or a zinc anode the electrocatalytic anode is replaced by an anode of active metal in a suitable anolyte. As mentioned ruthenium and ruthenium-based alloys are superior electrocatalysts for fuel cell cathodes using concentrated hydrogen peroxide as the oxidant. These electrocatalyst layers can also be deposited on the inert substrates. The inert substrates according to the present invention are resistant against the catholyte comprising the hydrogen peroxide oxidant such as carbon paper, carbon fiber fabric, activated carbon or carbon nanotubes metallized on a current collector. Nevertheless other materials such as conductive polymers such as PANI or nanotubes of a conductive polymer can be used as a substrate. Intrinsically conductive electronic conductive adhesives which are a Pressure Sensitive Adhesive (PSA) are more preferred as the electronic conductive adhesive because they are tacky adhesives without a solvent. the electrocatalyst particles and electrically connect them to the current collector without wetting the upper side of the electrocatalyst particles, which is electrochemically active. The preferred PSA-adhesives comprise a solution of the polyaniline dodecylbenzene sulfonic acid complex (PANI-DBSA), a polystyrene-b-poly (butylene-co-ethylene) -b-polystyrene polymer (SEBS, "polystyrene- block- (polyethylene-ran-polybutylene) -block-polystyrene ") and a sufficient amount of poly-α-pinene as a tackifying resin, in English," tackifier "in p-xylene, although other PANI- complexes such as PANI-CSA, other polymers such as polystyrene-b-polyisoprene-b-polystyrene or polystyrene-b-polybutadiene-b-polystyrene (SBS), or other tackifying resins such as rosin and esters of rosin could be used, too. PSA adhesives can be easily applied for example by screen printing. This simplifies the cathode manufacturing process of the present invention. The preferred fluorinated ionomer for adhesives comprising an ionomer is "NAFION" with an equivalent weight of 1100 g / mol, preferred dissolvent is a mixture of dimethyl sulfoxide, alcohols and water. According to one embodiment of the present invention the adhesive may comprise another graphite additive (for oxygen cathodes copper or silver may be employed) and another dopant such as dodecylbenzene sulfonic acid, camphor sulfonic acid or p-toluene sulfonic acid. The preferred additive is graphite powder.

BEST EXECUTION OF THE INVENTION The following examples illustrate the best way to perform the embodiments of the invention. Example 1 Preparation of a pressure-sensitive conductive adhesive 60 mg of PANI (emeraldine base) are placed in a beaker and 0.509 g of dodecylbenzene sulfonic acid (DBSA) are added. 5.5 ml of absolute ethanol are added and the solution is heated for 2 hours under magnetic stirring at 50 ° C. Finally the ethanol is removed by distillation. The product salt of PANI-DBSA is dissolved in 14 g of p-xylene. 6 g of this PANI-DBSA-solution in p-xylene are dissolved in 7 g of p-xylene. 0.51 g of a polystyrene-b-poly (butylene-co-ethylene) -b-polystyrene copolymer (SEBS) are dissolved in 5.5 g of p-xylene. 2.5 g of poly-α-pinene are added. The PANI-DBSA-solution and the SEBS-polya-pinene PSA are mixed and provide an inherently driven pressure-sensitive adhesive.

Example 2 Preparation of a Cathode with a PSA-Bonded Vulcan XC72R Catalyst A 3 cm x 1 cm carbon paper web (Toray TGP-H-120 manufactured by Toray Industries America Inc., New York, USA) is coated with the conductive adhesive which is pressure sensitive in Example 1. The adhesive is dried before coating the electrode with the electrocatalyst. 12.9 mg of the electrocatalyst are distributed on the adhesive layer. The pressure may be applied to coat the electrode as it immerses in an electrocatalyst battery and an excess of electrocatalyst may be removed with a brush. Preferred is the electrostatic application of the electrocatalyst powder.

The electrode is dried for 12 hours at room temperature and 2 minutes at 60 ° C. 1.0 ml of a solution of "NAFION" in water / alcohol (5%) is dripped onto the electrode. The excess solution can be removed from the edge of the electrode using a paper towel. The electrode is dried for 48 hours at room temperature before use.

Although the present invention has been described in detail and with reference to specific embodiments, other versions are possible. For example, it is possible to glue a layer of carbon black as a pre-catalyst instead of the electrocatalyst on the adhesive layer which will be converted to the electrocatalyst by applying a salt of a metal and an agent. reducer. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions presented here.

All features described in this specification (including the appended claims, the abstract and the drawings) may be replaced by alternative features for the same uses, equivalent uses or the like, unless expressly stated otherwise. Thus, unless otherwise expressly indicated, each feature described is an example only of a generic series of equivalent or similar features. To the extent that the above description and accompanying drawings disclose an additional object that is not within the scope of the claims below, the inventions are not dedicated to the public and the right to file one or more patents for these additional inventions is reserved.

Claims (15)

CLAIMS: 1. An electrode for a fuel cell, which comprises (a) a substrate; (b) a conductive adhesive, which conducts electrons intrinsically, on a surface of said substrate; (c) an electrocatalyst which is adhered to said substrate by said conductive adhesive, which conducts electrons intrinsically; and (d) an ion conductive layer in contact with said electrocatalyst. An electrode according to claim 1, wherein said substrate comprises one of the following: (a) a current collector; or (b) a gas diffusion layer. An electrode according to claims 1 to 2, wherein said conductive adhesive is a pressure-sensitive adhesive. An electrode according to claims 1 to 3, wherein said conductive adhesive comprises at least one intrinsic electronically conductive polymer selected from the group consisting of polyaniline, substituted polyanilines, polythiophene, poly (3,4-ethylenedioxythiophene), other substituted polythiophenes, polypyrroles, polyparaphenylenes, polyazulenes, polyfurans, polyindoles, polypyridines, polypyrazines, polytriazines, polythiazoles, polyimidazoles, polyquinolines, polybenzimidazoles, polytriazoles, polyoxydiazoles, polycarbazoles, polybenzothiophenes, polybenzofurans, polyheptadiyne, poly (para-phenylene vinylenes), as well as copolymers of these polymers. An electrode according to claims 1 to 4, wherein said conductive adhesive further comprises at least one dopant. 13 An electrode according to claim 5, wherein said dopant is a sulfonic acid. An electrode according to claims 5 to 6, wherein said dopant is selected from the group consisting of dodecylbenzene sulfonic acid, dinonylnaphthalene sulfonic acid, and camphorsulfonic acid. An electrode according to claims 3 to 7, wherein said electronic conductive adhesive further comprises at least one tackifying agent. An electrode according to claims 3 to 8, wherein said electronically conductive adhesive further comprises an elastomer. 10. A bipolar electrode comprising an anode which is electrically connected and mechanically attached to a cathode according to claims 1 to 9. 11. A membrane electrode assembly comprising an ionomer membrane which is pressed to the ionomer layer of an electrode according to claims 2 to 10 and another electrode comprising at least (a) a substrate; and (b) a layer of an electrocatalyst, which is pressed on the other side of the ionomer membrane. 20 A fuel cell comprising at least one of the following: (a) an electrode according to claims 1 to 10; or (b) a membrane electrode assembly according to claim 11. 25 A process for producing a catalyst coated substrate in a method of manufacturing a membrane electrode assembly or an electrode for fuel cells comprising: a) a substrate; b) applying a conductive adhesive, which conducts electrons intrinsically, to a surface of said substrate; c) an electrocatalyst is spread on the layer of said conductive adhesive after the application of the conductive adhesive. A method of manufacturing a catalyst-coated substrate according to claim 13, further comprising the step of: applying a layer of an ionomer to the layer of said electrocatalyst after spreading of the electrocatalyst. A process for producing a catalyst coated substrate according to claims 13 to 14, characterized in that said conductive adhesive is a pressure-sensitive adhesive. 10 15 20 25 30