Synthesis of β-FeOOH and α-Fe ₂ O ₃ nanorods and electrochemical properties of β-FeOOH

β-FeOOH nanorods with a tunnel-type structure were synthesized via a hydrothermal method at low temperature and characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA) and galvanostatic tests. From TEM bright-field images, a rodlike morphology with an average diameter of 30 ± 5 nm and an average length of 400 nm (aspect ratio ≈ 13) is observed. Electrochemical tests show that thesew nanorods deliver a large discharge capacity of 275 mA h g−1vs. Li metal at 0.1 mA cm−2 (voltage window 1.5–4.2 V). α-Fe2O3 nanorods with a regular pore structure were obtained by calcining the as-synthesized FeOOH at 520 °C.