A carboxymethyl vegetable gum as a robust water soluble binder for silicon anodes in lithium-ion batteries

The dramatic volume change and electrode pulverization hinder the practical utilization of silicon-based anodes for lithium-ion batteries. Studies show that binders can be an effective approach to solve these issues. Herein, the natural vegetable gum-guar gum (GG) is modified through carboxymethylation method. The carboxymethyl guar gum (CMGG) exhibits rapid water solubility, excellent thermal stability, high viscosity and robust adhesion. When it is applied as a binder for silicon anodes, the CMGG possessing affluent hydroxyl and carboxyl groups can effectively accommodate the significant volume variations of silicon particles through the formation of intensive hydrogen bonds. The Si @ CMGG electrode not only retains a high reversible capacity of 1865 mAh g−1 after 200 cycles with a capacity decay rate of 0.12% for each cycle, but also holds a capacity of 1287.1 mAh g−1 after 100 cycles with high mass loading of 1.15 mg cm−2. Furthermore, the CMGG binder can promote the lithium-ion transport like guar gum and reduce the electrode polarization, which is helpful in maintaining the electrochemical stability of Si anodes at high current density.