Conformation-Driven Dispersion Control of Carbon Black by Carboxymethyl Cellulose: Implication for Binder-Particle Interactions

The dispersion stability of Li-ion battery slurries is important for the processing and performance of energy storage systems. Sodium carboxymethyl cellulose (CMC) is a representative polymer binder commonly used in anode slurries; however, the effect of its molecular structure, especially altered by the degree of substitution (DS), on the dispersion and stability of carbon black (CB) particles is known only empirically. In this study, we analyze how the varying molecular structure of the polymer binder affects the CB dispersion in both solution and dried states. The influence of DS on the molecular conformation of CMC and its effects on the adsorption behavior and interaction between CB and CMC are carefully investigated through a comprehensive study employing rheological, dielectric, and scattering analysis. Our findings suggest that DS is a key element of the CMC structure, which can significantly affect the CMC–CB interaction and consequently affect the CB dispersion structure and stability. We expect that our results will contribute to a better understanding of the interaction between polymer and particles and thus improve the slurry processing in various energy applications.