Abstract: The present invention relates to a crosslinked unreinforced cellulose hydrate membrane crosslinked using at least two different crosslinking agents, to a method for the production thereof and to the use of the crosslinked unreinforced cellulose hydrate membrane according to the invention.

Abstract: The present invention relates to a crosslinked unreinforced cellulose hydrate membrane crosslinked using at least two different crosslinking agents, to a method for the production thereof and to the use of the crosslinked unreinforced cellulose hydrate membrane according to the invention.

Abstract: The present invention relates to a polymer electrolyte membrane for fuel cells, comprising a polymer matrix of at least one basic polymer and one or more doping agents, wherein particles containing ionogenic groups and having a mean particle diameter in the nanometer range are embedded in the polymer matrix and the particles containing ionogenic groups are distributed homogeneously in the polymer matrix in a concentration of less than 50% relative to the weight of the polymer matrix, as well as to the production and use of same, especially in high-temperature fuel cells.

Abstract: The invention relates to hybrid membranes that are composed of an organic polymer and an inorganic polymer, a method for producing hybrid membranes, and the use of said hybrid membranes in polymer electrolyte membrane fuel cells. The inventive hybrid membranes comprise at least one alkaline organic polymer and at least one inorganic polymer. Said polymers are blended together at a molecular level. The inorganic polymer is formed from at least one precursor monomer when the membrane is produced. The disclosed membranes are characterized in that the same are provided with high absorptivity for doping agents, have a high degree of mechanical and thermal stability in both an undoped and doped state, and feature permanently high proton conductivity.

Abstract: The invention relates to a gas diffusion electrode for polymer electrolyte fuel cells having a working temperature of up to 250° C., comprising a plurality of gas-permeable electroconductive layers having at least one gas diffusion layer and one catalyst layer. The catalyst layer contains particles of an average particle diameter in the nanometer range, said particles containing ionogenic groups. The invention also relates to the production of said gas diffusion electrode and to the use of same in high-temperature polymer electrolyte membrane fuel cells.

Abstract: The invention relates to the use of a material imparting proton conductivity in the production of fuel cells, said material consisting of monomer units and having an irregular shape.

Abstract: A membrane for fuel cells, which is characterized by a homogeneous absorption and good retention of doping agents, and which guarantees a high mechanical stability at high temperatures when doped. Such membranes consist of at least one polymer, whose nitrogen atoms are chemically bonded to a central atom of a derivative of a polybasic inorganic oxo acid. The membranes are produced from polymer solutions that are devoid of water and oxo acid derivatives, by heating the solution that has been introduced into a membrane mold until a self-supporting membrane has been formed and then by thermally regulating the latter. Inventive fuel cells having a membrane electrode assembly (MEA) that comprises a membrane of the invention and phosphoric acid as the doping agent have, for example, an impedance of 0.5-1 ?cm2 at a measuring frequency of 1000 Hz and at an operating temperature of 160° C. and a gas flow for hydrogen of 170 mL/min and for air of 570 mL/min.

Abstract: A membrane-electrode assembly and polymer electrolyte fuel cells and methods of production thereof, in which a polymer membrane, containing at least one basic polymer membrane, is sandwiched between two flat gas diffusion electrodes each of which is loaded with a dopant, whereby after reaching a mass transport equilibrium for the exchange of the dopant between the gas diffusion electrodes and the polymer membrane, the polymer membrane has a conductivity of at least 0.1 S/m at a temperature of no less than 25° C.

Abstract: The present invention relates to a polymer electrolyte membrane for fuel cells, comprising a polymer matrix of at least one basic polymer and one or more doping agents, wherein particles containing ionogenic groups and having a mean particle diameter in the nanometer range are embedded in the polymer matrix and the particles containing ionogenic groups are distributed homogeneously in the polymer matrix in a concentration of less than 50% relative to the weight of the polymer matrix, as well as to the production and use of same, especially in high-temperature fuel cells.

Abstract: A proton-conducting electrolyte membrane is disclosed, comprising at least one base material and at least one dopant, which is the reaction product of an at least dibasic inorganic acid with an organic compound, comprising one acidic hydroxyl group, or the condensation product of said compound with a polybasic acid. The membrane may be produced by a single step method, which avoids the use of dangerous materials and environmental pollutants. Subsequent doping of the membrane, e.g., in conjunction with assembly of the membrane electrode assembly (MEA) is not excluded. The electrolyte membrane has a high and constant mechanical stability and flexibility, excellent chemical and thermal stability and a high and constant conductivity. The membrane may be used in a fuel cell in a wide temperature range from 50° C. to more than 200° C., for example, whereby the fuel cell has a high and constant power level over the entire temperature range.

Abstract: A membrane electrode assembly (MEA) for a fuel cell, which has a planar polymer membrane. This membrane, in a tangentially inner area, is coated on both sides with electrode structure, and, in a tangentially outer area projecting at least on one side beyond the electrode structure coating, is connected to a sealing member. A marginal zone of the polymer membrane is embedded in the elastomer sealing member. The sealing member extends tangentially inward to a transition area that lies tangentially between the outer area and the inner area, where it overlaps the electrode structures on outer faces of the electrode structures, on both of the sides of the polymer membrane.

Abstract: The invention relates to hybrid membranes that are composed of an organic polymer and an inorganic polymer, a method for producing hybrid membranes, and the use of said hybrid membranes in polymer electrolyte membrane fuel cells. The inventive hybrid membranes comprise at least one alkaline organic polymer and at least one inorganic polymer. Said polymers are blended together at a molecular level. The inorganic polymer is formed from at least one precursor monomer when the membrane is produced. The disclosed membranes are characterized in that the same are provided with high absorptivity for doping agents, have a high degree of mechanical and thermal stability in both an undoped and doped state, and feature permanently high proton conductivity.

Abstract: The invention provides an improved fuel cell system and a method of operating a fuel cell, which ensure that the fuel cell can be operated at high efficiency without irreversible damage. The fuel cell system according to the invention has at least one fuel cell with a fuel cell stack and with separator plates, which are equipped with inlets and outlets for a heat transfer medium, a thermostat, a heat transfer medium circuit, which has a transport device for the heat transfer medium and includes at least the fuel cell and the thermostat, at least one temperature sensor for the fuel cell and a monitoring and control unit for the temperature of the fuel cell. With the invention it is possible to operate the fuel cell in a range close to the preset optimum operating temperature.

Abstract: The invention relates to a fuel-cell installation comprising: a reformer stage, which can be heated by a gas burner in order to carry out the water-vapour reformation of hydrocarbon and water-vapour into hydrogen and additional reformer products; at least one conversion stage, which is connected downstream of the reformer stage for the chemical preparation of the reformer products; and at least one fuel-cell stack, which is connected downstream of the conversion stage and comprises a plurality of anodes and cathodes with corresponding supply and discharge connections for converting the hydrogen into water to generate an electric current and heat. The fuel-cell stack is configured as a high-temperature fuel-cell stack with an operating temperature between about 100° C. and about 200° C.

Abstract: The invention relates to a fuel-cell stack with an external media supply, comprising a plurality of stacked fuel-cell elements, each containing a proton-conductive polymer membrane, which is located between a flat anode electrode and a flat cathode electrode, each electrode being in contact with a separator plate containing canal structures for supplying a reaction gas, evacuating superfluous reaction gas and water that has been produced and/or for distributing a heat transfer medium. At least one collection/distribution container, which is connected to the canal structures of a plurality of separator plates, distributes the reaction gas or the heat transfer medium or collects superfluous reaction gas and water that has been produced or the heat transfer medium. The collection/distribution container is configured as a hood that covers a plurality of fuel-cell elements, the edge of said hood being sealed in relation to the covered elements.

Abstract: The invention relates to an insulating element for a fuel cell stack, which is composed of a thermally insulating plastic or plastic composite material. The insulating element is connected to the end plate and the bipolar end plate of the stack and achieves virtually uniform distribution of temperature and flow density along the fuel cell stack in the cell operating mode. As a result, the condensation of product water is prevented.

Abstract: Gas diffusion electrodes with improved proton conduction between an electrocatalyst located in a catalyst layer and an adjacent polymer electrolyte membrane, capable of being used at operating temperatures up to or above the boiling point of water, ensuring lasting high gas permeability. Also, a production method and corresponding fuel cells. At least one part of the particles of an electrically conductive carrier material in the catalyst layer is at least partially loaded with at least one porous, proton-conducting polymer which can be used up to or above the boiling point of water. Loading and development of the porous structure is carried out in a phase inversion method. The gas diffusion electrodes can be used in high temperature fuel cells working at temperatures up to or above the boiling temperature of water without a drop in performance in continuous operation.

Abstract: A membrane-electrode assembly and polymer electrolyte fuel cells and methods of production thereof, in which a polymer membrane, containing at least one basic polymer membrane, is sandwiched between two flat gas diffusion electrodes each of which is loaded with a dopant, whereby after reaching a mass transport equilibrium for the exchange of the dopant between the gas diffusion electrodes and the polymer membrane, the polymer membrane has a conductivity of at least 0.1 S/m at a temperature of no less than 25° C.

Abstract: A membrane electrode assembly (MEA) for a fuel cell, which has a planar polymer membrane. This membrane, in a tangentially inner area, is coated on both sides with electrode structure, and, in a tangentially outer area projecting at least on one side beyond the electrode structure coating, is connected to a sealing member. A marginal zone of the polymer membrane is embedded in the elastomer sealing member. The sealing member extends tangentially inward to a transition area that lies tangentially between the outer area and the inner area, where it overlaps the electrode structures on outer faces of the electrode structures, on both of the sides of the polymer membrane.

Abstract: A membrane for fuel cells, which is characterized by a homogeneous absorption and good retention of doping agents, and which guarantees a high mechanical stability at high temperatures when doped. Such membranes consist of at least one polymer, whose nitrogen atoms are chemically bonded to a central atom of a derivative of a polybasic inorganic oxo acid. The membranes are produced from polymer solutions that are devoid of water and oxo acid derivatives, by heating the solution that has been introduced into a membrane mold until a self-supporting membrane has been formed and then by thermally regulating the latter. Inventive fuel cells having a membrane electrode assembly (MEA) that comprises a membrane of the invention and phosphoric acid as the doping agent have, for example, an impedance of 0.5-1 ?cm2 at a measuring frequency of 1000 Hz and at an operating temperature of 160° C. and a gas flow for hydrogen of 170 mL/min and for air of 570 mL/min.