Facile Fabrication of SiOx-Coated Graphite via 3-aminopropyltriethoxysilane-Assisted Surface Modification for Lithium-Ion Battery Anodes

초록

Silicon is a promising anode material for lithium-ion batteries (LIBs) due to its high capacity (up to 4,200 mAh g-1), significantly exceeding that of graphite (372 mAh g-1). However, silicon-based anodes suffer from severe volume expansion and unstable solid electrolyte interphase (SEI) formation during cycling. In this study, we present a simple and scalable approach to fabricate SiOx-coated graphite composites by impregnating commercial graphite with 3-aminopropyltriethoxysilane (APTES) followed by controlled heat treatment. By varying the APTES concentration and annealing temperature, the SiOx coating thickness and Si content within the composite were effectively tuned. The optimized composite, prepared using an APTES:toluene volume ratio of 90:10 and heat-treated at 800 degrees C under Ar/H2, delivered an initial reversible capacity of 532 mAh g-1 with capacity retention of 92 % after 100 cycles at 0.5 C. Electrochemical impedance spectroscopy analysis revealed that the formation of a condensed Si-O-Si network effectively reduced the charge-transfer resistance and enhanced SEI stability. These results demonstrate that the effectiveness of APTES-derived SiOx coatings as a practical strategy to achieve high-capacity and long-life anodes for next-generation LIBs.

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