Experimental and in silico simulation of slot-die coating with a polymer electrolyte fuel cell catalyst slurry

Abstract

The causes of coating irregularities in high-speed slot-die coating of catalyst slurries for polymer electrolyte fuel cells (PEFCs) have not been determined. Accordingly, in this study, slot-die-coating experiments and computer simulations of two-phase gas–liquid flow were conducted to explore coating instability in the high-speed coating of PEFC catalyst slurries applied through slot-die coating. The results obtained from experiments and simulations were consistent. A thinner target layer and a faster coating, causing non-uniform coating. This is caused by movement of the gas–liquid interface on the upstream side and side of the die, which entraps the gas phase. Viscosity and surface tension are important, and a lower ethanol content in the solvent increases surface tension and lowers viscosity, improving coating stability.