pH-Dependent Conformation and Rheological Behaviors of Sodium Carboxymethyl Cellulose: An Integrated Experimental and Molecular Dynamics Study

The lithium-ion battery anode slurry is a complex mixture of active materials, conductive additives, binders, and solvents. Sodium carboxymethyl cellulose (CMC), a representative binder, functions as a dispersant, thickener, and gelling agent, where its minor content change can greatly affect macroscopic slurry properties. The rheological behavior of CMC is highly pH-dependent: at high pH, carboxyl deprotonation induces electrostatic repulsion, leading to chain extension. However, acidic conditions at low pH diminish these repulsions via protonation, allowing hydrophobic patches and hydrogen bonding to drive physical gelation. Here, we investigate the rheological behavior and microscopic conformation change of CMC aqueous solutions in reponse to pH variations, using an integrated approach of experimental rheometry and molecular dynamics (MD) simulation. These insights provide a theoretical foundation to extend to complex slurries, offering perspectives for optimizing battery electrode manufacturing.