Manhattan Scientifics, Inc.

Petra Koschany

An electrode with adjustable gas permeability for electrochemical cells is formed by first and second laminated thin layers. The first serves for determining the overall gas permeability through the thickness of the electrode and conducting electricity. The second is for conducting electricity, supplying the reaction gases and removing the reaction products, and is a porous electricity-conducting material. The laminate consists of at least two materials of different gas permeability. The material with the higher gas permeability located on the side of the membrane forms the first layer, and the material with the lower gas permeability forms the second layer on the side away from the membrane. Openings are formed in the laminate towards the side adjacent to the membrane. The sidewalls of the openings in the area of the material with the higher gas permeability are at least partially covered by the material with the lower gas permeability.

Electrodes with adjustable gas permeability, and method of producing such electrodes

For simplifying cooling of a fuel cell system which may be a single cell (), a stack () or a similar configuration and which comprises at least one active membrane () sandwiched between an anode layer () and a cathode layer () and comprising a catalyst, a fuel supply having access to the anode layer and an air supply () having access to the cathode layer, while at the same time keeping the effectivity of the system with reference to energy conversion, volume and weight favourable, the fuel cell system is to be operated such that the air which is supplied by the air supply, is introduced by pressure into the fuel cell system, passes along the cathode layer and then leaves the fuel cell system, is used for both oxidant and coolant. For this purpose, the air is introduced into the fuel cell system () with a rate resulting in a stoichiometric rate in the range between 25 and 140.

Method of operating a fuel cell system, and fuel cell system operable accordingly

For an improved cooling a fuel cell stack ( ) with cooling fins extending around the periphery of the stack, the section of the stack has a somewhat longitudinal shape. In detail, the stack comprises: a plurality of fuel cells electrically connected in series and having equivalent active section areas and circumferences, each fuel cell comprising a laminate of layers, these comprising an electrolyte membrane and catalyst, electrode and gas diffusion layers the functions of which may be combined in any combination in multifunction layers; end and separator plates delimiting each cell; and cooling layers ( ) the cooling function of which also may be combined with other layers in respective multifunction layers, the cooling layers each projecting beyond the circumferential outer periphery ( ) of the laminate of the outer layers thereby comprising an inner active section area ( ) and a peripheral cooling fin area ( ). For extending the circumference of the active area ( ) and thereby the section of the cooling layer and the area of the fins, the ratio ( ) of circumference ( ) and active area ( ) of the stack ( ), defined by the geometrical shape of the active area ( ), extends the corresponding ratio of a square active area. Also describe is the use of expanded graphite for one or several of the following components of a fuel cell: bipolar plate, electrode, and gas diffusion layer.

Fuel cell stack with cooling fins and use of expanded graphite in fuel cells

According to known methods, gas chambers of fuel cells are sealed by applying pressure. A small space always remains between the electrode and the membrane. According to the inventive sealing method, the bipolar plate and the membrane-electrode unit are bonded with a curable polymer. A gas-proof assembly is obtained by applying an adhesive bead on the outer periphery of the gas chamber and around the inner gas ducts. These assemblies can be stacked and bonded together according to the present invention to form a stack of polymer electrolyte fuel cells. The inventive assemblies which are composed of a bipolar plate and a membrane-electrode unit can be used in polymer electrolyte fuel cells and in corresponding electrolytic cells. These assemblies have such a small weight that they can be used in mobile devices in a particularly advantageous manner.

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Salzweg, Germany

Petra Koschany