Facile synthesis of multi-phase (Si+SiO2)@C anode materials for lithium-ion batteries

Abstract

To bring about a revolution in energy storage through Li-ion batteries, it is crucial to develop a scalable preparation method for Si-based composite anodes. However, the severe volume expansion and poor ionic transport properties of Si-based composites present significant challenges. Previous research focused on SiO and nano Si/C composites to address these issues. In this study, mechanical milling was used to introduce a SiO_x layer onto the surface of Si by mixing Si and SiO₂ in a 1 : 1 mass ratio. The resulting Si+SiO₂ composites (denoted as SS50) exhibited an initial coulombic efficiency (ICE) of 73.5% and high rate performance. To further stabilize the overall structure, kerosene was introduced as a carbon source precursor to generate a coating layer. The resulting multiphase composite structure (SiO_x+SiO₂+C), designated as SS50-900C, demonstrated a capacity retention of 79.5% over 280 cycles at its capacity of 487 mA h g⁻¹. These results suggest that a cost-effective mechanical ball milling refinement of Si+SiO₂ and a gas-phase encapsulation process can significantly improve the electrochemical performance of Si-based composites.