Characterization of slurries for lithium-ion battery cathodes by measuring their flow and change in hydrostatic pressure over time and clarification of the relationship between slurry and cathode properties

Abstract

Hypothesis: It is important to elucidate the effect of the particle dispersion/aggregation state of electrode slurries on resulting electrodes for the development of superior lithium-ion batteries. Many studies have been conducted to characterize cathode slurries for lithium-ion batteries; however, the particle dispersion state of cathode slurries remains unclear. This study investigates the rheological behavior and the packing ability of the cathode slurries for obtaining a denser electrode with lower electric resistance.Experiments: In addition to the conventional flow curve measurement, we measured the changes in the hydrostatic pressure of the slurries with time to evaluate their packing ability. The relationship between the properties of the cathode slurries and those of the as-cast cathodes was also investigated.Findings: It was found that a slurry in which acetylene black powder forms a network structure, with sufficient strength and the ability to rapidly recover after breaking, yields a cathode with comparatively high density and comparatively low volume resistivity. It was also found that the normalized settling time of a cathode slurry determined from its change in hydrostatic pressure over time correlates well with both the density and volume resistivity of a resulting as-cast cathode.