Scalable and Cost-Effective Preparation of Hierarchical Porous Silicon with a High Conversion Yield for Superior Lithium-Ion Storage

Although some reported porous silicon-based anode materials manifest excellent lithium-ion storage properties, their scalable and economical synthesis remains a large obstacle to their industrial application. This work presents a scalable and efficient preparation of hierarchical porous silicon by using cost-effective porous SiO2 as raw material through a modified magnesiothermic reduction approach, in which a rotatable furnace was employed and the hydrofluoric acid (HF) etching treatment was avoided. Moreover, the reaction has a high conversion yield (>95%). Subsequently, a carbon layer with a thickness of 7 nm has been conformally wrapped onto the surface of the porous silicon through a chemical vapor deposition (CVD) process. The obtained porous Si@C composite exhibits a high reversible capacity at 0.3 Ag-1, and retained ca. 40% of its capacity even at 8 Ag-1. Moreover, it has an excellent capacity retention over 300 cycles. The strategies disclosed in the present work and the novel porous Si@C composite may have great potential for the next generation of lithium-ion batteries.