Investigation of Solvent and Carbon Particles Behavior during Drying Process from Catalyst Ink to Catalyst Layer

The electrical resistance and evaporation rate of a slurry composed of a solvent, carbon and ionomer were measured. Electrical resistance was measured with a four-point probe, and the evaporation rate was monitored with an electric balance. The drying is a key process for porous electrode fabrication such as catalyst layers used in proton exchange membrane fuel cells. Carbon particles behavior affects a formed porous structure, and it can affect cell performance. Solvent evaporation is also important to understand dynamics in the drying process of the slurry. Electrical resistance and weight variation represent carbon agglomeration and solvent evaporation, respectively. Three types of the slurry which differ in carbon content were measured. The higher carbon content slurry took a shorter time for agglomeration and drying. The difference of the agglomeration time and the drying time is larger in the low carbon content slurry. This result indicates that the agglomeration proceed not only by solvent evaporation.