Multidimensional Branched Composite Binder via Covalent Grafting for High-Performance Silicon-Based Anodes

A binder plays an essential role in preserving the mechanicalstabilityof electrodes and in enhancing the cycle life of Si anodes. Nevertheless,the typical binders normally are not effective enough to relieve theunavoidable volume expansion of Si during cycling. Herein, to makefull use of the polar functional groups on the polymer backbone, thecitric acid-grafted poly(acrylic acid) (CA-g-PAA)composite binder is rationally designed and prepared by a simple graftmodification. The CA molecule not only provides more reactive groupsbut also connects with PAA to form a multidimensional branched structure.Due to the interaction of CA and PAA, the proposed binder (CA-g-PAA) demonstrates enhanced adhesion strength. Thus, theCA-g-PAA/Si electrode retains a high discharge specificcapacity of 2482.3 mAh g(-1) after 300 cycles at 840mA g(-1) and exhibits a better structural integrity.This study highlights the synergistic interaction of CA and PAA withSi particles and offers a simple path for the design of optimizedbinders.