Forschungszentrum Julich Gmbh

Hendrik Dohle

Detlef Stolten

Volker Peinecke

Jürgen Mergel

Thorsten Kels

Ilona Busenbender

Martin Müller

Jan Bringmann

Thomas Bewer

Helmut Baltruschat

Hans-Friedrich Oetjen

Thorsten Wüster

Jan Stalling

Thomas Beckmann

Anne Bendzulla

Ayhan Egmen

Robert Deja

Roland Peters

Birgit Schumacher

In low-temperature fuel cells according to prior art, the problem often arises that the diffusion layer of the cathode is filled by water which is permeated or produced on the cathode, such that oxygen can no longer be transported to the catalyst layer of the cathode in a frictionless manner. As a result, said fuel cells are regularly used with a high excess of oxygen in order to reduce the cited transport problems for the oxygen. The inventive fuel cell enables said problem to be solved in that the arrangement of the diffusion layer and the catalyst layer of the cathode is inverted. The diffusion layer, which is embodied in such a way as to also conduct ions, is directly adjacent to the electrolyte membrane. The catalyst layer oriented towards the free cathode space can advantageously directly react with the supplied oxygen without further transport problems. A further advantage lies in the fact that the water produced on the catalyst layer of the cathode and/or permeated by the electrolyte membrane and the diffusion layer can be easily withdrawn via the free cathode space.

Cathode for a direct methanol fuel cell and method for operating the same

The invention relates to a fuel cell stack in which, according to the invention, several elements of the fuel cell stack are advantageously sealed by a seal in order to form a continuous operating material channel. The inventive fuel cell stack can be provided with a very compact design, whereby the layer thickness of an individual fuel cell is, on a regular basis, distinctly less than 1.5 mm and, advantageously, even less than 1.2 mm.

Reactant sealing for fuel cell stack

In a direct-methanol fuel cell stack with an at least partial circulation () of the fuel, according to the invention a means is arranged in this circulation for reducing the concentration of an undesired byproduct. This means is comprised especially of a further electrochemical cell () to which electric current is applied and which at least partly transforms the byproducts by an electrochemical reduction reaction again to methanol and water. Since the concentration of byproducts is small, the loss in electric current required for the additional reduction reaction has no noticeable effect on the efficiency of the fuel cell stack.

Fuel cell stack with circuit

An electrode-electrolyte unit for a fuel cell which prevents the permeation of the fuel used or the permeation of water through the electrolyte layer. An electrolyte is subdivided into two electrolyte layers with a barrier layer disposed between them. The barrier layer is permeable only to protons and may be coated with a catalytically active porous layer having a high effective surface area. A porous layer on the side of the unit facing the cathode increases the electrochemically active surface area and a porous layer on the side of the unit facing the anode ensures that a sufficient amount of hydrogen is dissolved. The fuel used can be hydrogen or methanol and suitable electrolytes include membranes or other solid or liquid electrolytes.

Fuel cell electrode-electrolyte unit

In a fuel cell arrangement with at least one fuel cell operated by a fuel and an oxidizing agent, means are provided for effecting gravity driven circulation of the fuel and the oxidizing agent through the fuel cell so that no pumping means, which consume power and need servicing, are required.

Fuel cell arrangement with gravity-driven circulation system

Growing community of inventors

Stolberg, Germany

Hendrik Dohle