Rheological assessment of dispersion in electrode slurries using sequence of physical processes (SPP) analysis

초록

Particle-polymer mixtures are widely used in industries such as secondary batteries and fuel cells, owing to their enhanced properties derived from complex particle-polymer interactions and microstructures. The dispersion state in the mixtures critically affects processability and product performance yet remains difficult to assess in such complex systems. This study introduces a novel diagnostic approach based on the Sequence of Physical Processes (SPP) methodology under Large Amplitude Oscillatory Shear (LAOS) to characterize dispersion states. Using a model electrode slurry with varying polymeric dispersant concentrations, four distinct dispersion states were identified, each represented by unique patterns on the Cole-Cole plot. Low or excessive dispersant contents produced single deltoid patterns, indicating dominant particle-particle or polymer-polymer interactions. Between these extremes, double deltoid patterns emerged, gradually evolving with increasing amounts of polymeric dispersant. This behavior was ascribed to enhanced dispersion stability resulting from increased polymer content, which reduced particle attraction and suppressed shear-induced aggregation. The interpretation of dispersion state changes based on LAOS-SPP analysis is consistent with the results of microscopy-based cluster analysis and filtration tests. Our results highlight the potential of LAOS-SPP analysis as an efficient tool for diagnosing dispersion quality in complex systems.

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