Carboxymethyl chitosan: A new water soluble binder for Si anode of Li-ion batteries

Carboxymethyl chitosan (C-chitosan) is investigated as a new water soluble binder for Si anode of Li-ion batteries. The Fourier transformation infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements reveal that the strong hydrogen bonding is formed between the hydroxylated Si surface and the polar groups (–OH, –COOH and –NH 2 ) of C-chitosan. The Si/C-chitosan anode (Si:carbon black:C-chitosan = 62:30:8 in weight ratio) exhibits a high first discharge capacity (4270 mAh g −1 ) with a first coulombic efficiency of 89%, and maintains a capacity of 950 mAh g −1 at the current density of 500 mA g −1 over 50 cycles.