Membrane electrode assembly fabrication process for directly coating catalyzed gas diffusion layers

A new fabrication process to manufacture a membrane electrode assembly (MEA) by extrusion slot coating of ionomer onto a catalyzed gas diffusion layer (GDL) is presented. Preliminary coating tests were conducted to study the feasibility and effectiveness of directly coating Nafion D2021 onto catalyzed Toray 060 carbon paper. The uniformity of the coated membrane and the penetration of the Nafion dispersion into the catalyst layer were analyzed. Pressing and blowing operations were introduced into the fabrication process to increase the membrane uniformity and to decrease the penetration of Nafion dispersion. The effects of these operations were analyzed. The performance of MEAs fabricated using the new process was measured and compared with MEAs made by traditional methods. It was found that MEAs formed by direct coating have similar electrochemical performance at current densities below 0.8 Acm ² as MEAs traditionally fabricated.