Enhancing the Strucural and Electrochemical Stability of SiOx Anodes via Precursor-Controlled Carbon Coatings

초록

Abstract Silicon monoxide (SiOx) has attracted significant attention as a next-generation anode material for lithium-ion batteries due to its high theoretical capacity and relatively moderate volume change compared to pure silicon. However, its low intrinsic electrical conductivity and unstable solid?electrolyte interphase (SEI) still lead to poor cycling stability and limited rate capability. To overcome these challenges, surface modification through carbon coating has been considered an effective strategy to enhance the conductivity and interfacial stability of SiOx-based anodes. In this study, SiOx particles were coated with carbon layers using different hydrocarbon precursors?methane (CH4), ethylene (C2H4), and propane (C3H8)?via chemical vapor deposition (CVD). SEM and TEM analyses revealed distinct coating morphologies depending on the precursor type: CH4 produced vertically grown carbon nanostructures, C2H4 formed smooth and uniform amorphous carbon layers, and C3H8 resulted in partially irregular carbon coatings with an intermediate texture. These structural differences critically affected lithium-ion transport and SEI stability during cycling. In particular, the C2H4-derived coating exhibited Enhanced conductivity and mechanical integrity, effectively mitigating the volumetric changes of SiOx and stabilizing the electrode/electrolyte interface. Electrochemical analyses confirmed that the C2H4-coated SiOx electrode maintained stable cycling performance with improved capacity retention, while the bare SiOx suffered from severe capacity fading and unstable SEI formation. The results clearly demonstrate that controlling the carbon microstructure through precursor selection is a key factor in optimizing the electrochemical performance of SiOx@C composite anodes. This study provides practical insight into the design of structurally robust SiOx-based anodes for advanced lithium-ion batteries.