Metallic gas diffusion layers for polymer electrolyte fuel cells

Porous carbon materials are widely used as gas diffusion layers (GDL) in polymer electrolyte fuel cells (PEFCs). Further improvements of these carbon materials are required, including cost reduction and improved mechanical strength. For example, the low mechanical strength of carbon-based GDLs limits the extent to which they can be thinned to reduce PEFC size and cost. Here, the applicability of various metallic GDLs is examined for reducing thickness and cost. Stainless steel GDLs coated with gold (Au) were prepared via physical vapor deposition, as a proof-of-concept. It is revealed that a thin Au coating results in reduced overvoltage and improved cell performance. Whilst Au is expensive and should eventually be replaced with inexpensive materials for practical applications, this work shows that conventional metallic materials could be applied as GDLs if the electrical contact is sufficiently improved.