Abstract: A multi-layer diffusion medium substrate having improved mechanical properties is disclosed. The diffusion medium substrate includes at least one stiff layer and at least one compressible layer. The at least one stiff layer has a greater stiffness in the x-y direction as compared to the at least one compressible layer. The at least one compressible layer has a greater compressibility in the z direction. A method of fabricating a multi-layer diffusion medium substrate is also disclosed.

Abstract: A gas diffusion media for a fuel cell, such as a proton exchange membrane fuel cell, is provided. The gas diffusion media includes carbonizable acrylic pulp fibers instead of conventional phenolic resin as a binder material. The acrylic fibers are mixed with the carbon fiber dispersion during the papermaking step, thus eliminating the phenolic resin impregnation step typically associated with conventional gas diffusion media manufacturing processes. The mat is then cured and carbonized to produce gas diffusion media.

Abstract: A diffusion medium for use in a PEM fuel cell contains hydrophobic and hydrophilic areas for improved water management. A hydrophobic polymer such as a fluororesin is deposited on the paper to define the hydrophobic areas, and an electroconductive polymer such as polyaniline or polypyrrole is deposited on the papers defining the hydrophilic areas. In various embodiments, a matrix of hydrophobic and hydrophilic areas on the carbon fiber based diffusion media is created by electropolymerization of a hydrophilic polymer onto a diffusion medium which has been previously coated with a hydrophobic polymer such as a fluorocarbon polymer. When an aqueous solution containing monomers for electropolymerization is contacted with a fluorocarbon coated diffusion medium, the hydrophilic polymer will be preferentially deposited on areas of the carbon fiber based diffusion medium that are not covered by the fluorocarbons.

Abstract: The present invention provides a fuel cell having a membrane electrode assembly disposed between a first diffusion media that has a first set of material characteristics and a second diffusion media that has a second set of material characteristics. The membrane electrode assembly and the first and second diffusion media provide a cell assembly. The cell assembly provides a water transport mechanism that selectively controls water transportation across a thickness of the first and second diffusion media and through the membrane electrode assembly. The first set of material characteristics has at least one material characteristic substantially different from at least one material characteristic of the second set of material characteristics. The selection of the first and second set of material characteristics defines the water transport mechanism for managing hydration of the first and the second diffusion media.

Abstract: A method of making an electrode is provided. The method includes providing an electrocatalyst decal comprising a carrying substrate having a nanostructured thin catalytic layer thereon; providing a transfer substrate with an adjacent adhesive layer; adhering the nanostructured thin catalytic layer adjacent to the adhesive layer to form a composite structure; removing the carrying substrate from the composite structure; and removing the transfer substrate from the composite structure to form the stand-alone nanostructured thin catalytic film comprising the adhesive layer with the nanostructured thin catalytic layer adhered thereto. A stand alone nanostructured thin catalytic film and methods of constructing electrodes with the stand alone nanostructured thin catalytic films are also described.

Abstract: A method of depositing a conductive material is described. The method includes: providing a plate selected from anode plates, cathode plates, bipolar plates, or combinations thereof, wherein the plate includes gas flow channels; providing a diffusion media in contact with the gas flow channel side of the plate to form an assembly; introducing a gaseous precursor of the conductive material into the assembly using a chemical vapor infiltration process; infiltrating the gaseous precursor into the diffusion media and gas flow channels of the plates; and depositing a coating of the conductive material on the diffusion media, the gas flow channels of the plate, or both. An assembly having a CVI conductive coating and a fuel cell incorporating the diffusion media having the CVI conductive coating are also described.

Abstract: A bipolar plate for use in a proton exchange membrane fuel cell having an electrically conductive polymer coated on at least one region of a surface of the plate in contact with a flow field. The coated region is hydrophobic or hydrophilic as compared to an uncoated region of the surface to prevent liquid accumulation. Electroconductive polymer coatings are applied by electrochemical polymerization.

Abstract: In at least certain embodiments, the present invention provides a diffusion media and fuel cells and systems employing the diffusion media. In at least one embodiment, the diffusion media comprises a porous matrix having an outer surface and a hydrophilic polymeric coating on at least a portion of the porous matrix with the hydrophilic coating comprising the cured product of a formulation comprising a hydrophilic monomer.

Abstract: A catalyst ink composition for a fuel cell electrode is provided. The catalyst ink composition includes a plurality of electrically conductive support particles; a catalyst formed from a finely divided precious metal, the catalyst supported by the conductive support particles; an ionomer; at least one solvent; and a reinforcing material configured to bridge and distribute stresses across the electrically conductive support particles of the ink composition upon a drying thereof. An electrode for a fuel cell and a method of fabricating the electrode with the catalyst ink composition are also provided.

Abstract: A catalyst ink composition for a fuel cell electrode is provided. The catalyst ink composition includes a plurality of electrically conductive support particles; a catalyst formed from a finely divided precious metal, the catalyst supported by the conductive support particles; an ionomer; at least one solvent; and a reinforcing material configured to bridge and distribute stresses across the electrically conductive support particles of the ink composition upon a drying thereof. An electrode for a fuel cell and a method of fabricating the electrode with the catalyst ink composition are also provided.

Abstract: A method of transferring nanostructured thin catalytic layers to a gas diffusion layer and thus making a catalyst coated diffusion media is described. The method includes treating the gas diffusion layer with a temporary adhesive to temporarily increase the adhesion strength within the microporous layer and to carbon fiber paper substrate, transferring the nanostructured thin catalytic layer to the microporous side of a gas diffusion media layer. The nanostructured thin catalytic layer can then be further processed, including adding additional components or layers to the nanostructured thin catalytic layer on the gas diffusion media layer. Preparation of catalyst coated diffusion media and a catalyst coated diffusion media based membrane electrode assembly (MEA) are also described.

Abstract: A method of making an electrode ink containing nanostructured catalyst elements is described. The method comprises providing an electrocatalyst decal comprising a carrying substrate having a nanostructured thin catalytic layer thereon, the nanostructure thin catalytic layer comprising nanostructured catalyst elements; providing a transfer substrate with an adhesive thereon; transferring the nanostructured thin catalytic layer from the carrying substrate to the transfer substrate; removing the nanostructured catalyst elements from the transfer substrate; providing an electrode ink solvent; and dispersing the nanostructured catalyst elements in the electrode ink solvent. Electrode inks, coated substrates, and membrane electrode assemblies made from the method are also described.

Abstract: A method of transferring a nanostructured thin catalytic layer from its carrying substrate to a porous transfer substrate and further processing and restructuring the nanostructured thin catalytic layer on the porous transfer substrate is provided. The method includes transferring the nanostructured catalytic layer from its carrying substrate to a transfer substrate. The nanostructured catalytic layer then is processed and reconstructed, including removing the residual materials and adding additional components or layers to the nanostructured catalytic layer, on the transfer substrate. Methods of fabricating catalyst coated membranes with the reconstructed electrode including the nanostructured thin catalytic layer, reconstructed electrode decals, and catalyst coated proton exchange membranes are also described.

Abstract: A method of making a reconstructed electrode having a plurality of nanostructured thin catalytic layers is provided. The method includes combining a donor decal comprising at least one nanostructured thin catalytic layer on a substrate with an acceptor decal comprising a porous substrate and at least one nanostructured thin catalytic layer. The donor decal and acceptor decal are bonded together using a temporary adhesive, and the donor substrate is removed. The temporary adhesive is then removed with appropriate solvents. Catalyst coated proton exchange membranes and catalyst coated diffusion media made from the reconstructed electrode decals having a plurality of nanostructured thin catalytic layers are also described.

Abstract: A process comprising: depositing a liquid bonding layer comprising an ionomer and a solvent over a carrier film; placing a decal substrate over the liquid bonding layer and drying the liquid bonding layer to provide a solid bonding layer comprising the ionomer, and the solid bonding layer bonding the decal substrate and carrier film together.

Abstract: A fuel cell including a water blocking layer positioned between anode gas flow channels and a gas diffusion media. The blocking layer prevents water from propagating through the gas diffusion media layer and entering the anode flow channels, while allowing gas from the flow channels to flow through the diffusion media layer to the membrane. A water accumulation channel can be provided around the perimeter of the gas diffusion media layer where blocked water is accumulated, and allowed to expand during cell freezing. A porous capillary wick can be provided in the accumulation channel for wicking water to the inlet end of the flow channels where it is used to humidify the anode gas coming into the fuel cell. The wick can have a tapered configuration so that it has a larger diameter at the gas input end of the flow channels.

Abstract: Diffusion media for use in PEM fuel cells are provided with silicone coatings. The media are made of a porous electroconductive substrate, a first hydrophobic fluorocarbon polymer coating adhered to the substrate, and a second coating comprising a hydrophobic silicone polymer adhered to the substrate. The substrate is preferably a carbon fiber paper, the hydrophobic fluorocarbon polymer is PTFE or similar polymer, and the silicone is moisture curable.

Abstract: Diffusion media for use in PEM fuel cells are provided with silicone coatings. The media are made of a porous electroconductive substrate, a first hydrophobic fluorocarbon polymer coating adhered to the substrate, and a second coating comprising a hydrophobic silicone polymer adhered to the substrate. The substrate is preferably a carbon fiber paper, the hydrophobic fluorocarbon polymer is PTFE or similar polymer, and the silicone is moisture curable.

Abstract: A gas diffusion layer for use in fuel cells includes a gas permeable diffusion structure and a microporous layer. The microporous layer incorporates a plurality of particles of anisotropic shape, simultaneously reducing the porosity of the microporous layer and increasing the tortuosity for gas transporting through the microporous layer. The anisotropic particles in the microporous layer are present in a first amount such that the gas diffusion layer has an increased gas transport resistance.

Abstract: A gas diffusion layer for use in fuel cells comprises a fiber and non-fiber material in a ratio such that the water vapor diffusion transport resistance is greater than 0.8 s/cm measured at 80 C and 150 kPa absolute gas pressure when the gas diffusion layer has a thickness less than or equal to 300 microns. Another gas diffusion layer comprises a fiber and non-fiber material in a ratio such that the water vapor diffusion transport resistance is lower than 0.4 s/cm measured at 80 C and 150 kPa absolute gas pressure when the gas diffusion layer has a thickness greater than or equal to 100 microns. Fuel cells incorporating the gas diffusion layers are also provided.