Covalent organic framework-modified poly acrylic acid binder enhances cycling performance of silicon-carbon anodes

Abstract

In lithium-ion (Li-ion) batteries, silicon-carbon (Si/C) composite anodes undergo substantial volume fluctuations during cycling, leading to structural degradation and performance deterioration. To address this challenge, a novel binder, PAA@Tp-DCAP-COF, was developed by incorporating a small proportion of covalent organic frameworks (COFs) into poly(acrylic acid) (PAA). Leveraging the unique porous structure and functional groups of COFs, this binder strengthens the chemical interactions with the Si/C anode, significantly enhancing the electrochemical performance of silicon-based anodes. Experimental results demonstrate that electrodes employing PAA@Tp-DCAP-COF as the binder maintain a capacity of 727.9 mAh g -1 after 250 cycles at a 1.5C rate, achieving a capacity retention rate of 77.32%. In contrast, electrodes using pure PAA as the binder retain only 505.5 mAh g -1 under identical conditions. Moreover, varying the proportion of COF addition further modulates the enhancement in electrochemical performance. Scanning electron microscopy (SEM) and nano-indentation analyses confirm that PAA@Tp-DCAP-COF effectively mitigates volume expansion in Si/C anodes during cycling, thereby improving structural integrity and electrochemical stability.