Electrochemical Performance of Silicon-Graphite Composite Anodes Based on Polyacrylic Acid, Carboxymethyl Cellulose, and their Crosslinked Binders

초록

The growing demand for high-capacity, fast-charging lithium-ion batteries in electronic devices and electric vehicles has increased interest in silicon-graphite composite anodes. This study investigates the effect of binder composition on the electrochemical performance of composite electrodes containing 24 wt% silicon. Water-soluble binders-polyacrylic acid (PAA), carboxymethyl cellulose (CMC), and their crosslinked form (c-PAA-CMC)-are used to fabricate electrodes designated as PAA0 (CMC 100%), PAA50 (50% PAA-50% CMC), and PAA100 (PAA 100%). All electrodes are subjected to 1C galvanostatic cycling for 100 cycles. The PAA100 electrode exhibits the highest capacity retention (43.41%), compared to PAA50 (36.09%) and PAA0 (25.27%), highlighting the superior stability of the PAA binder. Scanning electron microscopy images reveal fewer surface cracks in PAA100 electrodes, indicating improved mechanical integrity. Electrochemical impedance spectroscopy (EIS) results show that the PAA100 electrode had up to 60% lower resistance, suggesting enhanced charge transport and interface stability. The findings suggest that PAA promotes early SEI formation and preserves electrode integrity during cycling. However, due to the high reactivity of silicon, continuous SEI growth contributes to irreversible capacity loss. Overall, the study underscores the importance of binder selection in improving the durability and fast-charging performance of high-silicon-content lithium-ion batteries.

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