Water-Soluble Binders for Lithium-Ion Battery Graphite Electrodes: Slurry Rheology, Coating Adhesion, and Electrochemical Performance

Water-processable composite electrodes are attractive both ecologically and economically. The binders sodium carboxymethyl cellulose (CMC-Na) and poly(sodium acrylate) (PAA-Na) were shown to have improved electrochemical performance over conventional binders. In many studies, a binder content of approximately 10 wt% has been applied, which is not suitable for large-scale electrode production due to viscosity and energy-density considerations. Therefore, we examined herein three electrode formulations with binder contents of 4 wt%, namely, CMC-Na: SBR (SBR= styrene butadiene rubber), PAA-Na, and CMC-Na: PAA-Na, on both laboratory and pilot scales. The formulations were evaluated on the basis of slurry rheology, coating adhesion, and electrochemical behavior in half-and full-cells. CMC-Na: SBR composites provided the best coating adhesion, independent of the mass loading and scale, and also showed the best capacity retention after 100 cycles. Previously reported merits of better cycling efficiencies and solid-electrolyte interphase formation for graphite-PAA composites appeared to vanish upon reducing the binder content to realistic levels.