In Situ Cross-linked Carboxymethyl Cellulose-Polyethylene Glycol Binder for Improving the Long-Term Cycle Life of Silicon Anodes in Li Ion Batteries

To increase the energy density of Li-ion batteries (LIBs), silicon has been widely studied due to its relative abundance and high theoretical specific capacity (similar to 3572 mAh g(-1)). However, silicon experiences drastic volume changes up to 300% associated with Li. Here, we report an in situ cross-linked carboxymethyl cellulose-polyethylene glycol (CMC-PEG) binder and its application to the silicon anode to improve cycle life. Through in situ cross linking during the electrode drying process, the cross-linked CMC-PEG binder is simply prepared without an additional process. In particular, the cross-linked CMC-PEG binder is effective in enhancing cohesion between active materials and adhesion between active materials and a current collector. The silicon anode with the cross-linked CMC-PEG binder shows stable cycling performance with a capacity of similar to 2000 mAh g(-1) up to 350 cycles at 0.5 C. In terms of simplicity, this binder has potential to be used for silicon anodes and other electrodes experiencing volume expansion during cycling.