Three-Dimensional Cross-Linked Binder Based on Ionic Bonding for a High-Performance SiO_x Anode in Lithium-Ion Batteries

Abstract

Non-negligible volume change is a troublesome problem for the commercial application of silicon oxide (SiOx). It is acknowledged that polymer binders' design is a promising method to promote the commercialization of SiOx. Herein, we proposed a three-dimensional (3D) dynamic cross-linked binder (CS-EDTA) via the ionic bonding between chitosan (CS) and ethylenediaminetetraacetic acid (EDTA). With excellent adhesive strength, CS-EDTA could tighten the connection of electrode constituents and prevent electrode delamination. Due to the reversible ionic bond, the 3D dynamic cross-linked structure of CS-EDTA could be repaired at ruptured points, which is favorable for alleviating the volume expansion of SiOx, resulting in enhanced structural stability of SiOx. Based on CS-EDTA, SiOx@CS-EDTA exhibits improved cycling stability and electrochemical kinetics compared with SiOx@CS. A capacity retention of 78% is achieved for SiOx@CS-EDTA after 200 cycles at 1.0 A g–1, delivering a reversible capacity of 721 mAh g–1. The assembled SiOx@CS-EDTA//LiNi0.6Co0.2Mn0.2O2 (NCM622) full-cell exhibits a superior energy density of 402 Wh kg–1.