Efficient transformation of rice husk to a high-performance Si@SiO2@C anode material by a mechanical milling and molten salt coactivated magnesiothermic reduction

Highlights: : • A new avenue is opened for transformation of rice husk to Si@C-based anode materials. • A novel magnesiothermic reduction with higher reducing power is designed. • The anode material obtained shows an electrochemically favorable microstructure. • The anode material obtained shows superior electrochemical performance. -- Abstract: A high-performance Si@SiO₂@C anode material for Li-ion batteries was obtained by a novel synthetic strategy based on a mechanical milling and molten salt coactivated magnesiothermic reduction at a low temperature of 200 °C, only using rice husk as the Si and C sources. The anode material obtained presented an electrochemically favorable architecture, in which crystalline Si particles with a size of ~15 nm were uniformly embedded in the amorphous carbon and SiO₂ matrix. The amount of the Si, SiO₂ and C components in the anode material was determined to be about 17.2, 24.5 and 58.3 wt%, respectively. Electrochemical analyses demonstrated that the Si@SiO₂@C anode material showed excellent electrochemical performance, delivering a reversible capacity of 1277.3 mAh g⁻¹ at a current density of 0.1 Ag⁻¹, still possessing a high capacity of 910.2 mAh g⁻¹ when increasing current density to 5 Ag⁻¹. After cycled for 200 cycles at 1.0 Ag⁻¹, the anode still preserved a reversible capacity of 973.1 mAh g⁻¹, showing a capacity retention of 93.1% and a Coulumbic efficiency higher than 99.7%. Importantly, the synthetic strategy is not only more facile and cost effective, but also more environmentally friendly, compared with those recently reported. Thus it is promising to be applied for large-scale transformation of rice husk to high-performance Si@C-based anode materials for Li-ion batteries.