Method for producing a gas diffusion device having improved electrical properties

A process for manufacturing a gas diffusion device, comprising:

• providing a superposition of a composite layer and an electrically conductive element, the composite layer including electrically conductive fibers and a polymerizable resin impregnating the electrically conductive fibers, and the electrically conductive element having an open porosity between a first face and a second face;
• compressing the superposition of the composite layer and the electrically conductive element so as to bring the electrically conductive fibers into contact with the first face of the electrically conductive element, so as to make the resin flow into the electrically conductive element without the resin impregnating all of a volume of said electrically conductive element;
• and
• polymerizing the resin having flowed and polymerizing the resin of the composite layer so that the composite layer becomes impermeable to hydrogen.