The Effect of Molecular Weight of Carboxymethyl Cellulose on the Dispersion of Silicon Suspensions Investigated by the Ultrasonic Degradation Method

Abstract

This study investigates the influence of the molecular weight of carboxymethyl cellulose (CMC) on the dispersion characteristics of silicon (Si) particles in Si/CMC model suspensions. The chain length of CMC is systematically adjusted, ranging from approximately 77 kDa to 281 kDa using the ultrasonic degradation method and characterized through the Mark-Houwink relation and gel permeation chromatography. Our findings confirm that decreasing CMC chain length enhances the dispersion of silicon particles by suppressing bridging flocculation, leading to a rapid reduction in the size of silicon agglomerates. The critical molecular weight required to disperse silicon particles with their primary size is found to be 190 kDa. This study highlights the benefits of utilizing low-molecular-weight CMC as a dispersant to effectively improve the dispersion of Si/CMC suspensions. Through a systematic exploration of the agglomeration behavior of silicon particles with varying molecular weight of CMC, valuable insights are provided regarding the optimal molecular weight necessary to mitigate severe agglomeration of silicon particles. We anticipate that this study contributes to the optimization and design of dispersants, thereby enhancing both the dispersion quality and the performance of silicon-containing electrodes.