Agglomeration and Peculiar Rheological Hysteresis Behavior of Electrode Slurries Containing Platinum-Supported Carbon and Ionomer

This study examined the correlation between particle agglomeration and the rheological properties of electrode slurries composed of porous electrode materials for polymer electrolyte fuel cells and presented two different agglomeration mechanisms in electrode slurries. Electrode slurries are used to fabricate porous electrodes. The state of electrode slurries is influenced by the materials, dispersion medium, and dispersion conditions, and is believed to affect the resulting porous electrode structure. However, the dispersion state of the materials within the electrode slurries remains inadequately understood. This study identified peculiar rheological behavior in the rheological measurements of electrode slurries, which arises depending on the composition ratio of the materials and dispersion conditions. The formation of two distinct particle agglomerate structures that differed in scale and formation mechanisms within the electrode slurries and their correlation with the rheological properties were revealed based on experimental approaches, including centrifugal classification, X-ray radiography, and rheo-small-angle X-ray scattering (rheo-SAXS).