Impact of Na-Carboxymethyl Cellulose Binder Type on Hard Carbon Performance and SEI Formation in Sodium-Ion Batteries

The development of hard carbon (HC) electrodes using biobased binders, formulated in water solvent, is of great interest for Na-ion batteries. Five Na-carboxymethyl cellulose (CMC) binders with different molecular weights and degrees of substitution were investigated. The increase in the CMC molecular weight led to an increase in the volume of water necessary for slurry preparation and a decrease in the electrode mass loading. Moreover, the adhesion of the slurry was strongly impacted by the aluminum current collector properties. A high initial Coulombic efficiency, iCE (up to ∼90%), and reversible capacity (up to 334 mAh g