α-Fe2O3 as an anode material with capacity rise and high rate capability for lithium-ion batteries

We report a simple molten salt method to prepare nanosize α-Fe2O3, as well as its electrochemical performance as anode material for lithium ion batteries. The structure and morphology were confirmed by Raman spectroscopy, X-ray diffraction, and transmission electron microscopy. The as-prepared α-Fe2O3 is a rhombohedral phase of hematite with crystal size in the range of 20–40 nm. The electrochemical measurements were performed using the as-prepared powders as the active material for a lithium-ion cell. The nanosized α-Fe2O3 shows excellent cycling performance and rate capability. It also exhibits the feature of capacity increase upon cycling. The outstanding electrochemical performance of the α-Fe2O3 can be related to several factors, namely, the short Li+ diffusion length along the porous rhombohedral structures and the nanosized nature of the materials, which decreases the traverse time for electrons and Li+ ions, and reduces the volume expansion to some extent during charge/discharge reactions.

Nanosized porous α-Fe2O3 powder was successfully synthesized via the molten salt method. Electrochemical measurement results demonstrated that the electrode properties of the α-Fe2O3 could offers excellent cycling performance and high rate capability. The capacity of the product shows two different trends during cycling which are rarely reported in the literature, a decrease in capacity in the first 100 cycles and an increase afterwards up to 600 cycles, with the lowest and highest capacity around 970 and 1972 mAh/g, respectively.Figure optionsDownload as PowerPoint slideResearch highlights
► Nanosized α-Fe2O3 as an anode material for lithium-ion battery.
► The nanosized α-Fe2O3 shows excellent electrochemical performance and exhibits the feature of capacity increase upon cycling.
► The porous rhombohedral structures of α-Fe2O3 could provides the short Li+ diffusion length, decreases the traverse time for electrons and Li+ ions, and reduces the volume expansion to some extent.
► The cubic structure of α-Fe2O3 has been modified to a needle-like structure after prolonged cycling.