Non-toxic synthesis of sandwich-like graphite sheet@Si@C anode material with strong face-to-face bonding by Si-C bonds for lithium-ion batteries

Abstract

Silicon/carbon-based anodes are considered to be the most promising materials for commercial application in next-generation lithium-ion batteries (LIBs) due to their high specific capacity. However, the non-toxic synthesis of nanoscale silicon and its robust bonding with carbon materials to maintain a stable solid electrolyte interphase (SEI) and suppress volume expansion is presented as a significant research challenge. In this work, semi-elliptical nanosilicon was synthesized on the surface of graphite sheets through physical vapor deposition (PVD), utilizing silicon vapors formed by the evaporation of micron silicon. A sandwich-like compete with strong face-to-face Si-C bonding, designated as graphite sheet@Si@Carbon-coating (GS@Si@C), was prepared through a combination of PVD and chemical vapor deposition (CVD). The preparation process is characterized by its non-toxicity and safety. The synergistic combination of GS and C coatings establishes an efficient electron transport network, thereby ensuring electrode stability. The strong face-to-face Si-C bonding facilities rapid electron/lithium-ion (Li+) transfer at the interface and also effectively suppresses volume expansion. Consequently, the GS@Si@C composite exhibits superior lithium storage performance, maintaining a specific capacity of 1028.5 mAh g−1 for 600 cycles at 2 A g−1, with a capacity retention of 85.9 % after 100 cycles at 0.5 A g−1 in GS@Si@C||LiFePO4 full cell. The investigation into GS@Si@C composite electrodes has demonstrated that enhanced connectivity and bonding at the silicon‑carbon interface could facilitate the development of high-performance silicon/carbon-based anode materials.