Nanoparticulate Fe₂O₃ and Fe₂O₃/C Composites as Anode Materials for Li-Ion Batteries

Lithium ion batteries (LIBs) have attracted extensive attention in various fields such us portable electronic devices or electric/hybrid electric vehicles owing to its high energy density, long cycle life, rapid charge capability, and no memory effect. For commercial LIBs, the positive electrode material is typically a metal oxide or phosphate while graphite is the most widely used anode material. However, to develop higher energy density systems new materials are required. In this sense, nanoparticulate and hybrid composites based on carbon coated metal oxides attract promising interest as high-performance electrode materials for next generation lithium-ion batteries (LIBs). In this study, nanoparticulate g-Fe₂O₃/C composites with different carbon proportion have been prepared by a freeze-drying synthesis procedure. The characterization has been performed by elemental analysis, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR), magnetic susceptibility measurements and Mossbauer spectroscopy. Morphological studies revealed that nanoparticles of g-Fe₂O₃ in the composites are well-dispersed in the matrix of amorphous carbon. The magnetic and spectroscopic measurements corroborated that described composition and morphology. The electrochemical study showed that composites with carbon have promising electrochemical performances. These samples yielded specific discharge capacities of 1200 mAh/g after operating for 100 cycles at 1C. These excellent results could be explained by the homogeneity of particle size and structure as well as the uniform distribution of g-Fe₂O₃ nanoparticles in the in situ generated amorphous carbon matrix.