Mixed ion-electron conductive binders coupling superior stiffness and toughness establish dual crosslinking stable silicon anodes

Abstract

The unstable solid electrolyte interface, huge volume expansion, and poor electrical conductivity severely hamper the commercial application of silicon (Si) anode with high capacity for next-generation lithium-ion batteries. Herein, a mixed ion–electron conductive (MIEC) binder coupling stiffness and toughness is designed to fabricate strong chemical bonds and physical hydrogen bonds with hydroxylated carbon nanotubes (CNT-OH) and Si particles by esterification reaction between sulfonic acid and hydroxyl groups. The dual crosslinking efficiently alleviates large stress from Si and maintains the electrodes’ structural integrity. The excellent synergistic effect of ion and electron conductivity of the prepared binder enhances the kinetics of lithium-ion and electron transport of the Si electrodes, achieving commercial areal capacity and a long lifespan. Thus, the Si anode with the prepared resultant binder delivers a high reversible capacity of 3079 mAh/g at 0.6 A/g after 200 cycles and retains a remarkable capacity of 2151 mAh/g at a high current density of 2 A/g even after 500 cycles. The work demonstrates the great potential of this binder design strategy to achieve the overall property promotion and practical feasibility of Si and other electrodes suffering from their low conductivity and dramatic volume changes.