Scaling of cathode paste dispersion processes in research applications using stress-based principles

In lithium-ion battery manufacturing, cathode slurry preparation is a critical step because electrode microstructure and resulting transport properties are fundamentally determined by carbon black (CB) dispersion quality, which directly governs cell performance. Scaling dispersion from laboratory to production scale is challenging, as consistent quality must be ensured while minimizing material waste and process variability. Since no established method captures particle-level interactions, macroscopic evaluation of stress behavior and flow conditions during dispersion is required as a basis for process-design and scale-up. This study introduces a macroscopic process model based on an active specific energy input, defined via an “active volume.” This volume represents the region in which CB particles experience sufficient stressing, governed by sufficiently high shear stresses (stress intensity) and higher stress frequency. Thus, the dispersion process is influenced by geometric and process parameters/variables. Therefore, disk diameter, vessel geometry, and dispersion time are systematically varied, while CB-particle size distributions are measured. To exclude effects of changing microscopic particle–particle interactions, the slurry properties are kept constant. The results show that dispersion cannot be scaled using classical geometric ratios (e.g., vessel-to-disk diameter), but must be based on stress intensity and active volume. Within geometric limits, the active volume depends on stirrer height and vessel diameter. The resulting dispersion model provides a framework for scale-up using the specific energy input weighted by the ratio of active to total suspension volume (“active specific energy”) as a promising control variable within the investigated parameter space, thus linking measurable process parameters to particle dispersion behavior. • Process parameter study on influence of carbon black decomposition regarding stress factors. • Introduction of active volume to estimate stress behavior during dispersion in dissolver. • Dispersion model and active volume enable scale-up using specific energy input as control variable.