Micro-tube biotemplate synthesis of Fe₃O₄/C composite as anode material for lithium-ion batteries

Highlights: • Fe₃O₄/C nanoparticles were successfully synthesized via a facile micro-tube method. • Easily available, carbon-rich kapok fibres play a dual role as the carbon source and the biotemplate. • As-prepared Fe₃O₄/C electrode exhibits notable cycle potential for anode material for LIBs. - Abstract: Kapok fibres were used as micro-tube biotemplate and bio-carbon source to synthesise Fe₃O₄/C composites, which were then utilised as anode materials. Fe₃O₄ nanoparticles were grown uniformly onto the external surface and internal channel of kapok carbon fibres. The flexibility, high specific surface area and electronic conduction of kapok fibres can buffer the volume expansion as well as inhibit the aggregation of Fe₃O₄ nanoparticles. Thus, the electrical integrity and structural of the Fe₃O₄/C composites electrode during lithiation/delithiation processes. The Fe₃O₄/C composites electrode delivers a high reversible capacity of 596 mA h g⁻¹ after 100 cycles and an ultra-high coulombic efficiency approaching 100%. The high electrochemical performance of the Fe₃O₄/C composites can be caused by the synergistic effect of the Fe₃O₄ nanoparticles and the structure of kapok carbon fibres.