In Situ Prepared Three-Dimensional Covalent and Hydrogen Bond Synergistic Binder to Boost the Performance of SiOx Anodes for Lithium-Ion Batteries

Polymer binders play an important role in enhancing the electrochemical performance of silicon-based anodes to alleviate the volume expansion for lithium-ion batteries. It is difficult for common one-dimensional (1D) linear binders to limit the volume expansion of a silicon-based electrode when combined with silicon-based particles with scant binding points. Therefore, it is necessary to design a three-dimensional (3D) network structure, which has multiple binding points with the silicon particles to dissipate the mechanical stress in the continuous charge and discharge circulation. Here, a covalent and hydrogen bond synergist 3D network green binder (poly(acrylic acid) (PAA)-dextrin 9 (Dex9)) was prepared by the simple in situ thermal condensation of a one-dimensional liner binder PAA and Dex in the electrode fabrication process. The optimized SiOx@PAA-Dex9 electrode exhibits an initial Coulombic efficiency (ICE) of 82.4% at a current density of 0.2 A g-1. At a high current density of 1 A g-1, it retains a capacity of 607 mAh g-1 after 300 cycles, which is approximately twice as high as that of the SiOx@PAA electrode. Furthermore, the results of in situ electrochemical dilatometry (ECD) and characterization of electrode structures demonstrate that the PAA-Dex9 binder can effectively buffer the huge volume change and maintain the integrity of the SiOx electrodes. The research overcomes the low electrochemical stability difficulty of the 3D binder and sheds light on developing the simple fabrication procedure of an electrode.