Improved interfacial adhesion of membrane electrode assemblies using polymer binders and pore-filling membranes in alkaline membrane fuel cells

Abstract

The development of alkaline membrane fuel cells (AMFCs) will enable the use of non-platinum catalysts and hydrocarbon-based electrolyte membranes. Such catalysts are intrinsically stable and have activities similar to that of platinum in an alkaline environment. A pore-filling membrane has been made from a porous, high-density polyethylene substrate to fabricate durable, AMFC membrane electrode assemblies (MEAs). Because of the low binding ability of the hydrocarbon ionomer in the preparation of AMFC MEAs, polymer binders were added to the catalyst slurries to form a firmly bound interface. A content of 20 wt% polyethylene (PE) binder, the same material as the porous substrate in the pore-filling membrane, exhibits the best attachment of the non-platinum catalyst particles to the pore-filling, hydrocarbon anion-exchange membranes. The addition of a PE binder improves adhesion at the MEA interface and diminished contact resistance. The improved durability of the MEA is confirmed by continuous, constant-voltage operation. Adhesion between the cathode catalyst layer and the pore-filling membrane is also investigated after mild hot-pressing to test the use of decal method in the fabrication of AMFCs. The catalyst layer with the PE binder was completely transferred to the pore-filling membrane at 50 °C and 30 bar cm−2, but not for the PTFE binder.