CONTEXT

The electrodes of fuel cells are generally composed of carbon that has been catalyzed, for example with Platinum except for high temperature operating fuel cell. The most common technique for producing a catalyzed electrode consists of using a carbon ink or cloth which is deposited on a substrate and then covered with a catalyst ink, for example, a platinum ink. The drawbacks of these techniques is that the layers are relatively thick, since the known ink deposition technique do not make it possible to create layers that are less than about ten micrometers thick.

TECHNICAL DESCRIPTION

The invention is based on the observation that, during the operation of a fuel cell, the quantity of catalyst that is actually usable corresponds to a thickness of no more than a few micrometers. Moreover, this usable quantity of catalyst depends on the current density supplied by the cell.

It would therefore be advantageous, for both economic and environmental reasons, to be able to adapt the quantity of catalyst to the operating mode of the cell, in order to deposit only the quantity necessary.

The present invention concerns a mehod for producing carbon electrodes for ion-conducting membrane fuel cells by deposition on an ion-conducting membrane. The method comprising the steps of alternately and/or simultaneously by plasma spraying in a vacuum chamber depositing porous carbon and a catalyst onto a ion-conducting membrane.The total thickness of catalyzed carbon in the electrode being less than 2 micrometers.

DEVELOPMENT STAGE

• Deposition process fully assessed on a laboratory scale;

=> 10 µg_Pt.cm^-2 per electrode Versus 0,2 -0,4  mg_Pt cm^-2

• Includes PdPt alloys with 1 µg_Pt.cm^-2 at the cathode and only Pd at anode; (see M. Mougenot et al Int. J.Hyd. Energy 2011)

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• Fuel cells containing said catalyzed electrode currently being assessed

=> 0,5 à 1 W cm^-2 versus 0,7 – 1 W cm^-2 efficiency is up to 250 kW.g_Pt^-1

BENEFITS

• Adaptation of the quantity of catalyst to the operating mode of the fuel cell;
• Quantity of Platinum reduced by a factor 5 to 10
• Thickness of catalyzed carbon less than 2 micrometers;
• Environmental and economical advantages.

INDUSTRIAL APPLICATIONS

The present technology aims at providing PEMFC manufacturers a process to producting advantageous membrane catalyzed carbon electrodes assemblies.