Suppressing Deformation of Silicon Anodes via Interfacial Synthesis for Fast-Charging Lithium-Ion Batteries

Abstract

Silicon anodes with high energy density are prone to mechanical deformation during cycling, including fracture, pulverization, and delamination from conductive materials, due to their large volume expansion and contraction. Although significant attention is paid to outer interface engineering such as surface coating and electrolyte design in order to maintain a steady solid electrolyte interphase (SEI), there are currently few strategies in place for stabilizing the inner interface between Si and conductive carbon host materials. In this work, it is reported that an interfacial SiC chemical bonding enhances the interaction between Si and carbon, which in turn suppresses nano-sized void evolution and ensues Si delamination. Through the open-edge structure of carbon nanotube (OCNT), it is demonstrated that graphitic edge planes enable to evoke of interfacial SiC specifically at the junction without overgrowth toward the bulk. As a result, an Si-graphite composite consisting of interfacial SiC exhibits a sF cycling life (79.5% for 300 cycles at 3C charging), as well as lower overpotential under high current density up to 5C compared to paired LiNi0.6Co0.2Mn0.2O2 (NCM) cathode in pouch full-cell tests. This study highlights the significance of inner interface engineering for developing high-energy density Si-based anodes toward fast charging and long-term stability.