Volume 50

The Effect of Solvated Ionomers on Coating Appearance in Wet Process Electrode of PEMFC Daozeng Yang, Bing Li, Daijun Yang, Pingwen Ming, Cunman Zhang

Abstract

In the realm of wet process electrode development for Proton Exchange Membrane Fuel Cells (PEMFCs), the rheological characteristics of the catalyst slurry play a pivotal role in shaping the coating appearance. The intricate interplay between solvated ionomers and catalysts gives rise to diverse and complex interactions, which in turn exert specific functions on aggregates, thus influencing the fluid properties significantly. This investigation utilizes rheological assessments to scrutinize the fluctuations in shear viscosity, viscoelastic behavior, and thixotropic properties of various water/alcohol slurries. The findings suggest that ethanol molecules, with their higher polarity, augment the surface potential of slurry aggregates, concomitantly diminishing slurry viscosity and compromising coating uniformity. This, however, leads to surface imperfections while enhancing the polarization efficiency of the membrane electrodes under high current densities, elevating the voltage output from 0.624V to 0.646V at 2A cm-2. Conversely, n-propanol molecules, relatively less polar, intensify the slurry’s viscosity and ameliorate surface flaws in the coating, thereby reducing the extra-large pore, exhibiting elevated polarization voltage at lower current densities, raising the voltage from 0.851V to 0.866V at 0.2A cm-2.

Keywords PEMFC, Catalyst slurry, Rheology, Coating appearance, Extra-large pore