<i>In Situ</i> Prepared Three-Dimensional\nCovalent and Hydrogen Bond Synergistic Binder to Boost the Performance\nof SiO_<i>x</i> Anodes for Lithium-Ion Batteries

Abstract

Polymer binders play an important\nrole in enhancing the\nelectrochemical\nperformance of silicon-based anodes to alleviate the volume expansion\nfor lithium-ion batteries. It is difficult for common one-dimensional\n(1D) linear binders to limit the volume expansion of a silicon-based\nelectrode when combined with silicon-based particles with scant binding\npoints. Therefore, it is necessary to design a three-dimensional (3D)\nnetwork structure, which has multiple binding points with the silicon\nparticles to dissipate the mechanical stress in the continuous charge\nand discharge circulation. Here, a covalent and hydrogen bond synergist\n3D network green binder (poly(acrylic acid) (PAA)–dextrin 9\n(Dex₉)) was prepared by the simple <i>in situ</i> thermal condensation of a one-dimensional liner binder PAA and Dex\nin the electrode fabrication process. The optimized SiO_<i>x</i>@PAA-Dex₉ electrode exhibits an initial\nCoulombic efficiency (ICE) of 82.4% at a current density of 0.2 A\ng^–1. At a high current density of 1 A g^–1, it retains a capacity of 607 mAh g^–1 after 300\ncycles, which is approximately twice as high as that of the SiO_<i>x</i>@PAA electrode. Furthermore, the results\nof <i>in situ</i> electrochemical dilatometry (ECD) and\ncharacterization of electrode structures demonstrate that the PAA-Dex₉ binder can effectively buffer the huge volume change and\nmaintain the integrity of the SiO_<i>x</i> electrodes.\nThe research overcomes the low electrochemical stability difficulty\nof the 3D binder and sheds light on developing the simple fabrication\nprocedure of an electrode.