Rational Design of Ion-Conducting and Interface-Optimized Acrylate-Based Network Binder Employed in Silicon/Graphite Anode for Li-ion Battery

Abstract

Silicon and graphite composites (Si/C) that is featured on 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 structure of anode and silicon expansion issues continue to pose daunting challenges. Herein, we propose an interface-optimized binder with high lithium-ion conductivity prepared by functional acrylate emulsion and subsequently crosslinked with lithiated carboxymethylcellulose (CMC-Li) in-situ to form a three-dimensional elastic network to achieve the reversible expansion of silicon in the restricted space. Improved interfacial bonding and a stronger affinity between the binder and Si/C anodes is achieved via supramolecular interactions of hydrogen bonding, π-π conjugation, and electrostatic effect. In addition, the introduction of numerous electron-rich oxygen-containing sites derived from acylate, combined with the lithiation strategy of CMC-Li helps Li+ within the battery system to transfer in an efficient and reasonable and manner. Accordingly, the Si/C anode with this binder obtained the highest initial coulombic efficiency (ICE) of 87.98% and reversible specific capacity of 462.3 mAh/g at 8C. This design strategy of the binder provides a novel concept for long-cycle and high-power Si/C anodes.