The rational design of an ion-conducting and interface-optimized acrylate-based network binder employed in a silicon/graphite anode for Li-ion batteries

Abstract

Silicon and graphite composites (Si/C), which feature higher capacities than graphite and lower expansion effects than silicon, have become one of the most promising alternatives to commercial graphite anodes. However, the complex interfacial structures of anodes and silicon expansion issues continue to pose daunting challenges. Herein, we propose an interface-optimized binder with high lithium-ion conductivity prepared from a functional acrylate emulsion that was subsequently crosslinked with lithiated carboxymethyl cellulose (CMC-Li) in situ to form a three-dimensional elastic network to achieve the reversible expansion of silicon in restricted space. Improved interfacial bonding and stronger affinity between the binder and Si/C anode are achieved via the supramolecular interactions of hydrogen bonding, π–π conjugation, and electrostatic effects. Moreover, numerous electron-rich oxygen-containing sites from acylate groups, combined with the lithiation strategy of CMC-Li, promote efficient and orderly Li⁺ transfer within the battery system. Accordingly, a Si/C anode with this binder obtained the highest initial coulombic efficiency (ICE) of 87.98% and a reversible specific capacity of 462.3 mAh g⁻¹ at 8C. This design strategy involving a binder provides a novel concept for long-cycle-life and high-power Si/C anodes.