Micro-sized and Nano-sized Fe_3O_4 Particles as Anode Materials for Lithium-ion Batteries

Micro-sized (1030.3§178.4 nm) and nano-sized (50.4±8.0 nm) Fe3O4 particles have been fabricated through hydrogen thermal reduction of α-Fe₂O₃ particles synthesized by means of a hydrothermal process. The morphology and microstructure of the micro-sized and the nano-sized Fe₃O₄ particles were characterized by X-ray diffraction, field-emission gun scanning electron microscopy, transmission electron microscopy and high-resolution electron microscopy. The micro-sized Fe₃O₄ particles exhibit porous structure, while the nano-sized Fe₃O₄ particles are solid structure. Their electrochemical performance was also evaluated. The nano-sized solid Fe₃O₄ particles exhibit gradual capacity fading with initial discharge capacity of 1083.1 mAhg¡1 and reversible capacity retention of 32.6% over 50 cycles. Interestingly, the micro-sized porous Fe₃O₄ particles display very stable capacity-cycling behavior, with initial discharge capacity of 887.5 mAhg¡1 and charge capacity of 684.4 mAhg⁻¹ at the 50th cycle. Therefore, 77.1% of the reversible capacity can be maintained over 50 cycles. The micro-sized porous Fe₃O₄ particles with facile synthesis, good cycling performance and high capacity retention are promising candidate as anode materials for high energy-density lithium-ion batteries.