Effects of interactions between binders and different-sized silicons on dispersion homogeneity of anodes and electrochemistry of lithium-silicon batteries

Abstract

This study compares the dispersion of submicron-silicon and nano-sized silicon powders and the electrochemistry of the prepared anodes using carboxymethyl cellulose or guar gum as the binder. Carboxymethyl cellulose is found to be a better binder than guar gum for the electrochemistry of the anodes when the electrode active powder is submicron-silicon because carboxymethyl cellulose helps the dispersion of submicron-silicon while guar gum gels submicron-silicon in the electrode slurry. In contrast, guar gum is a better binder than carboxymethyl cellulose for cell performance when the active anode material is nano-sized silicon, which is much more oxidized on its surface. Batteries prepared with nano-sized silicon present a capacity below 1500 mAh g−1 at a current of 420 mA g−1 and poor initial Coulombic efficiency below 85%. For anodes using submicron-silicon as the active material, the constructed cells exhibit a capacity above 2500 mAh g−1 and good initial Coulombic efficiency above 93%.