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

Abstract

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.

Impact of Water-Based Binder on the Electrochemical Performance of P2-Na0.67Mn0.6Fe0.25Co0.15O2 Electrodes in Na-Ion Batteries

“…However, in the case of the NaMFC_CMC electrode, the surface morphology is different and seems to be only composed of carbon ( Figure 3b) indicating that the active material is not properly embedded in the CMC binder/conductive carbon matrix. The NaMFC particles were only detected inside the numerous cracks observed at the surface of the electrode, which are commonly reported for water-based electrodes and are mainly caused by the preferred absorption of the CMC on the electrode components compared to the current collector [1][2][3]. The cross section pictures confirm the observation made on the surface of the electrodes.…”

“…As an example, electrode preparation usually requires an efficient drying process generating additional costs and major safety issues appear with the use of the carcinogenic N-methyl pyrrolidone (NMP) solvent for designing polyvinylidene fluoride (PVDF) based electrodes. Therefore, efforts are being put into electrode preparation with aqueous binders such as carboxymethylcellulose (Na-CMC) and polyacrylic acid (PAA) [1][2][3].…”

Locust bean gum as green and water-soluble binder for LiFePO4 and Li4Ti5O12 electrodes

“…Many papers presented attempt to increase their energy density, power, cyclability, or reduce their cost. It is also expected that these batteries will be environmentally friendly [1][2][3][4]. There have been many efforts to optimize the components of LiBs to broaden the range of their potential applications.…”

Effect of carboxymethyl cellulose on the flow behavior of lithium-ion battery anode slurries and the electrical as well as mechanical properties of corresponding dry layers

“…The volume fluctuations can induce a local delamination of the electrode layer from the current collector and cracking within the layer. Hence, considerable research work dealt with the determination of adhesive strength between electrode layer and substrate [17,[33][34][35][36][37][38][39][40][41][42][43][44][45][46]. However, the cohesive strength in the electrode layer has not received much attention yet.…”