An environmental friendly cross-linked polysaccharide binder for silicon anode in lithium-ion batteries

Abstract

Silicon is a promising anode material for the next generation of lithium-ion batteries. Binder plays an essential role in maintaining electrode integrity when Si undergoes dramatic volume change during lithiation/delithiation processes. Herein, an environmental friendly water-soluble binder of oxidized starch cross-linked sodium carboxymethyl cellulose (OS-CMC) possessing three-dimensional (3D) network structure is designed. The abundant hydroxyl and carboxyl groups and the 3D structure of the cross-linked binder not only enhance the bonding with Si nanoparticles surface but also greatly alleviate the mechanical stress, thus maintaining the integrity of electrode and conductive network. In addition, it can facilitate faster lithium-ion transportation at the interface of Si/OS-CMC. As a result, the Si anodes with OS-CMC binder show good electrochemical stability and better mechanical properties than that of Si anodes with OS or CMC binder. The Si anodes with OS-CMC binder exhibit a discharge capacity of 1922 mAh g−1 after 100 cycles at a current density of 0.4 A g−1 with a high initial discharge capacity of 3424 mAh g−1 and maintain a superior capacity of 1667 mAh g−1 at a high current density of 8 A g−1. Our work provides a novel binder design for high-performance Si-based anodes.