Influence of Different Alginate and Carboxymethyl Cellulose Binders on Moisture Content, Electrode Structure, and Electrochemical Properties of Graphite-Based Anodes for Lithium-Ion Batteries

Abstract

Binders are one of the essential components in lithium-ion battery electrodes. Developments are focusing on high-capacity anodes in particular, which place special requirements on the water-based binder system, depending on material composition. Typically, the binders used are carboxymethyl cellulose (CMC) in combination with styrene butadiene rubber, but more environmentally friendly binders such as alginates (ALG) are also gaining importance. While many studies have addressed the synthesis and chemical interactions of these binders, most of them refer only to the material level and do not consider scalable manufacturing processes of the anodes. Moreover, the influence of binders on electrode structure and residual moisture is usually not, or insufficiently, considered. Accordingly, this study addresses the influence of CMC and ALG with different polymer structures (degree of substitution; M-/G-ratio) and molecular masses on processability, electrode structure, and performance. The findings suggest that different rheological properties (slurry) and electrode structures are produced, depending on the polymer type (CMC/ALG), and that both polymer type and electrode structure significantly influence residual moisture and adhesion strength. The electrochemical analysis is performed in coin full-cells. From this, recommended actions for binder material development as well as knowledge-based production processes for these anode material systems can be developed.