PAAS-β-CDp-PAA as a high-performance easily prepared and water-soluble composite binder for high-capacity silicon anodes in lithium-ion batteries

Abstract

The hyperbranched hydroxyl-rich water-soluble β-cyclodextrin polymer (β-CDp) is synthesized by the reaction between β-cyclodextrin and 1, 4-butanediol diglycidyl ether with a facile and environmentally friendly method, which is systematically confirmed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric (TG). A water-soluble PAAS-β-CDp-PAA binder is prepared by the esterification reaction between partially neutralized sodium polyacrylate (PAAS), β-CDp, and polyacrylic acid (PAA). Moreover, the optimized PAAS6-β-CDp1-PAA3 binder, with a three-dimensional (3D) cross-linked network structure constructed by covalent bonds, hydrogen bonds, and electrostatic interactions, displays a stronger adhesion between the active material and the current collector, effectively promotes the diffusion of Li+, and maintains the structural integrity of the electrode during charge-discharge cycling. Thus Si/PAAS6-β-CDp1-PAA3 electrode exhibits a higher initial discharge specific capacity of 3869 mAh g−1 with a columbic efficiency of 89.79% at 200 mA g−1, and a discharge specific capacity of 2513 mAh g−1 with a capacity retention rate of 71.10% is achieved after 100 cycles.