A study conducted by Soichiro Makino et al. has been published in the Journal of Colloid and Interface Science.
As electric vehicles become more widespread, the need for technologies that can mass produce high-quality lithium-ion batteries is growing. The dispersion state of the solid components in electrode slurries strongly influences both coating quality and battery performance. Conventionally, intensive kneading processes at high solid contents have been used to effectively homogenize slurries. Such processing is generally believed to improve slurry quality. Such processing is generally believed to improve slurry quality. However, significant slurry degradation, such as irreversible reductions in viscosity, have been observed in water-based anode slurries under these conditions.
In this study, we focus on carboxymethyl cellulose (CMC), a dispersantthat accounts for only approximately 1% of the slurry composition. We demonstrate that intensive kneading at high solid contents shortens the molecular chains of CMC, significantly decreasing the slurry's viscosity and elasticity. Consequently, the stability of the graphite particle dispersion deteriorates, promoting sedimentation and aggregation. This increases coating non-uniformity and defects. Additionally, we demonstrate that the decrease in liquid-phase viscosity facilitates the local segregation of the binder during drying. This results in increased electronic resistance in the final electrode. Furthermore, we propose a framework for evaluating kneading intensity by systematically organizing kneading speed and duration. This framework uses the "accumulated maximum shear strain," which represents the total deformation imposed on the material.
These findings are expected to contribute to the optimization of kneading conditions in electrode slurry processing by enabling a balance between dispersion efficiency and dispersant stability, and supporting the design of manufacturing processes for for the production of higher-quality batteries.
Title: High-Solid-Content Kneading Degrades Carboxymethyl Cellulose as a Dispersant and Destabilises Graphite Anode Slurries
Authors: Makino, S., Ishii, M., Kawauchi, S., Sasaki, M., Akimoto, Y., Nakamura, H.
Journal Name: Journal of Colloid and Interface Science
Published: December 1, 2025