Three-Dimensional\nCross-Linked Binder Based on Ionic\nBonding for a High-Performance SiO_<i>x</i> Anode\nin Lithium-Ion Batteries

Abstract

Non-negligible\nvolume change is a troublesome problem for the commercial\napplication of silicon oxide (SiO_<i>x</i>). It\nis acknowledged that polymer binders’ design is a promising\nmethod to promote the commercialization of SiO_<i>x</i>. Herein, we proposed a three-dimensional (3D) dynamic cross-linked\nbinder (CS-EDTA) via the ionic bonding between chitosan (CS) and ethylenediaminetetraacetic\nacid (EDTA). With excellent adhesive strength, CS-EDTA could tighten\nthe connection of electrode constituents and prevent electrode delamination.\nDue to the reversible ionic bond, the 3D dynamic cross-linked structure\nof CS-EDTA could be repaired at ruptured points, which is favorable\nfor alleviating the volume expansion of SiO_<i>x</i>, resulting in enhanced structural stability of SiO_<i>x</i>. Based on CS-EDTA, SiO_<i>x</i>@CS-EDTA exhibits improved cycling stability and electrochemical\nkinetics compared with SiO_<i>x</i>@CS. A capacity\nretention of 78% is achieved for SiO_<i>x</i>@CS-EDTA\nafter 200 cycles at 1.0 A g^–1, delivering a reversible\ncapacity of 721 mAh g^–1. The assembled SiO_<i>x</i>@CS-EDTA//LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) full-cell exhibits a superior energy\ndensity of 402 Wh kg^–1.