Investigation of the Adsorption Behavior of Sodium Carboxymethyl Cellulose on Carbon Black Towards the Understanding of Li-ion Battery Slurry Stability

Despite a great interest in Lithium-ion batteries (LIB) as a next-generation energy storage device, a fundamental understanding of the LIB slurry structure remains a challenge. The stability of LIB slurries can be problematic and must be understood for superior electrochemical properties and a long, stable life cycle. The role of polymer binders has been noticed in LIB slurries as they sustain the microstructure through physical or chemical adsorption to the particles during the electrode processing. However, the direct observation of the adsorption is challenging as typical imaging analyses are not available because of the opaque nature of LIB materials.

In this study, we attempt to investigate the adsorption behavior in the model system of sodium carboxymethyl cellulose (CMC) and carbon black (CB) from the perspective of CMC dynamics as the interaction between particle and polymer induces an inevitable conformational change of polymer. Employing broadband dielectric spectroscopy, the dynamic properties of CMC and the change of CMC dielectric responses with the CB were examined in detail. The dynamics of CMC were systemically investigated with varying degrees of substitution (DS) of CMC and CB content. The dynamics of CMC with lower DS have slowed down with more adsorption to CB, resulting in increased conductivity originating from the sturdier CB network.