Siemens Aktiengesellschaft

Pacesetter Ab

Armin Datz

Torsten Brandt

Arno Mattejat

Albert Hammerschmidt

Josef Lersch

Silke Latzel

Manfred Waidhas

Barbara Schricker

Konrad Mund

Joachim Hoffmann

Thomas Hammer

Norbert Huber

Helmut Markert

Florian Eder

Volker Muhrer

Peter Otschik

Herbert Hartnack

Bernhard Stapp

Ottmar Voitlein

Jochen Straub

Michael Schreyer

Walter Stühler

Klaus Dennerlein

Peter Donner

Andreas Reiner

Dieter Most

Carola Kuehn

Walter Stuehler

J Raghavendra Rao

Winfried Schaffrath

Gabriele Moesges, Deceased

Werner Straub

Anett Eder

Frank Baernreuther

Martin Tackenberg

Frank Barnreuther

Jochen SCHÄFER

Frank BÄRNREUTHER

Carola KÜHN

A fuel cell assembly with at least one PEM fuel cell for generating electrical energy from reactant gases includes at least one membrane/electrode having a membrane coated with platinum electrodes and, respectively positioned on each side, a porous gas diffusion layer, or having a membrane and, respectively positioned on each side, a porous gas diffusion layer coated with a platinum electrode, and also includes bipolar plates that lie against the gas diffusion layers and through which, during operation, a coolant flows, wherein at least one of the platinum electrodes has a smaller area than the gas diffusion layer, where the gas diffusion layer protrudes beyond the platinum electrode for a part of an edge region of the membrane/electrode unit, so that the formation of an electrochemical potential in this part of the edge region of the membrane/electrode unit is prevented in order to prevent damage to the membrane.

Fuel cell assembly and method for operating a fuel cell assembly

A fuel cell assembly with at least one proton exchange membrane (PEM) fuel cell for generating electrical energy from the reactant gases hydrogen and oxygen, which includes at least one membrane/electrode unit having a membrane that is coated with platinum electrodes and, respectively positioned on each side thereof, a porous gas diffusion layer, or which has a membrane and, respectively positioned on each side thereof, a porous gas diffusion layer that is coated with a platinum electrode, and which includes bipolar plates that lie against the gas diffusion layers and through which, during operation, a coolant flows, where access by at least one of the reactant gases to the membrane is blocked by a mechanical block for a part of an edge region of the membrane/electrode unit In order to prevent damage to the membrane.

An electrochemical cell has at least one plate element which can be cooled by a liquid coolant, such as water. The plate element has a surface that can be wetted for the purpose of cooling with the coolant. The surface of the plate element in the electrochemical cell is configured such that a contact angle between the surface and the liquid coolant is less than 90&#xb0;. In the method for producing the electrochemical cell an additional method step is carried out which influences the wettable surfaces of plate elements for cooling with coolant and by which a contact angle between the surface and the coolant is decreased.

Electrochemical cell

A humidification cell of a fuel cell apparatus includes a first outer plate and a second outer plate. A gas chamber, a humidification chamber and a water-permeable membrane separating the two chambers, are disposed between the first outer plate and the second outer plate, starting from the first outer plate. A first water-permeable support element that prevents fibers from detaching and also prevents medium flows from blocking narrow gas outlets, is disposed between the first outer plate and the membrane in such a way that the first support element is made of a filter material.

Humidification cell

A method for the dry production of a membrane-electrode unit includes assembling a layered configuration including a centrally positioned membrane produced by extrusion and pre-dried at a temperature between 80&#xb0; C. and 100&#xb0; C. for 15 min to 30 min, a substrate-electrode unit on each side of the membrane having an electrode layer applied to a substrate, an optional frame around each substrate-electrode unit for fixing the substrate-electrode unit, and two separating films on outer sides. The configuration is pressed together between two laminating rollers so that a pressure connection is produced at least between the membrane and the electrode layers. A short production time is achieved because it is not necessary to keep the membrane moist at high temperatures under pressure. A membrane electrode unit and a roller configuration are also provided.

Method for the dry production of a membrane electrode unit, membrane electrode unit, and roller arrangement

A gas diffusion electrode for a PEM fuel cell includes a metallic catalyst, and an electrocatalyst layer having a polymer A for hydrophobicizing the electrocatalyst layer and a uniform thickness of between 3 to 40 &#x3bc;m, especially 25 &#x3bc;m. The polymer A content is less than 10% by weight based on the metallic catalyst content. Methods of producing and of hydrophobicizing the electrode include screen printing a paste onto a carrier and removing the screen-printing medium by heating. The paste includes at least one metallic catalyst with a content of polymer A up to at most 10% by weight, and a screen-printing medium. The electrocatalyst layer of the electrode has a significantly lower content of the catalyst inhibitor TEFLON&#xae; because it is not added only to the screen-printing paste but is subsequently applied, with the same surface-specific effect, by dipping the finished electrocatalyst layer in a solution containing TEFLON&#xae;.

Gas diffusion electrode and method for its production

A screen-printing paste as a starting material for fabricating a gas diffusion electrode through screen-printing includes at least one polymer, at least one metallic catalyst, and a high-boiling solvent. The polymer is a binder including poly(butyl acrylate)-polymethacrylate copolymer, a poly(vinyl alcohol), and a poly(ethylene oxide). The polymer can be two polymers, a first being used for hydrophobicization and present in an amount of between 0 to 10% by weight based on a content of the metallic-catalyst, and a second being a binder. A screen-printing method of fabricating the electrode for a fuel cell includes forming a screen-printing layer having a thickness between 3 and 40 &mgr;m by applying the screen-printing paste to a base. The solvent and the polymer serve as a screen-printing medium. The screen-printing layer is baked to allow only residues of the solvent and the polymer to remain, which do not interfere with using the electrode in a fuel cell. The method uses a polybutylacrylate-polymethacrylate copolymer as a binder in the screen-printing paste.

Screen-printing paste and screen-printing method of fabricating a gas diffusion electrode

In a method for manufacturing a working electrode for an implantable, electrochemical oxygen sensor a thin layer of a uniform mixture composed of an epoxy-based resin, a hardener and powdered vitreous carbon is applied onto a ring or hollow cylinder of biocompatible, inert, electrically conductive material, and the resin is hardened.

Method for manufacturing a sensor electrode

Oxazolidinone structures-containing prepolymeric epoxy mixture

Siliconimides, which contain cross-linkable, functional groups, having the general formula ##STR1## in which the Q residues contain the functional groups.

Siliconimides

Growing community of inventors

Poxdorf, Germany

Armin Datz