Rice husk-derived hierarchical silicon/nitrogen-doped carbon/carbon nanotube spheres as low-cost and high-capacity anodes for lithium-ion batteries

Highlights: • Low-cost rice husks are utilized to fabricate Si-based anode material for Li-ion batteries. • Using electrospray method to fabricate homogeneous Si/N-doped carbon/CNT nano/micro-hierarchical structured spheres. • The unique hierarchical hybrid structure of the composite contributes to an excellent electrochemical performance. The fabrication of silicon anode materials using biomass resources enables the effective utilization of subsidiary agricultural products in battery industries, despite the electrochemical performances of these as-synthesized silicon materials still need improvements. Using rice husk (RH) as silicon source, here we report for the first time the fabrication of silicon/nitrogen-doped carbon/carbon nanotube (SNCC) nano/micro-hierarchical structured spheres through a facile electrospray approach. The unique hierarchical hybrid structure of the composite spheres, in which the silicon nanoparticles are homogenously encapsulated in the highly conductive, porous carbon matrix built by carbon nanotubes and nitrogen-doped carbon, contributes to fast electronic transport and prevents silicon from pulverization possessing good structure stability upon the synergistic lithiation/delithiation of the components. These SNCC spheres could deliver a high reversible specific capacity of 1380 mA h g⁻¹ at a current density of 0.5 A g⁻¹, and still maintain 1031 mA h g⁻¹ after 100 cycles. The low cost RH-derived silicon composites synthesized by a facile, scalable synthetic method turn out to be promising for the next-generation rechargeable lithium-ion batteries.