Investigation of Solvent Effects on the Dispersion of Carbon Agglomerates and Nafion Ionomer Particles in Catalyst Inks Using Ultra Small Angle X-Ray Scattering Method

Ink formulation is important to improve the performance of membrane electrode assembly (MEA) in polymer electrode fuel cells (PEMFCs). In this study, ultra-small angle x-ray scattering method was applied to study the dispersion of carbon black in different solvent to get a better understanding of the influence of the solvent on the dispersion of carbon black. The dimension of carbon black aggregates before and after adding Nafion ionomer was compared in different solvent. Dielectric constant and viscosity were found to be the key factors that affect the dispersion of carbon black in solvents. Carbon black particles in a solvent with higher dielectric constant will tend to form larger aggregates after adding Nafion ionomer. The higher viscosity of a solvent will prevent the aggregation of carbon black particles after the addition of Nafion ionomer.