Mg intercalation properties into open-ended vanadium oxide nanotubes

Vanadium oxide nanotubes (VOx-NTs) were obtained as the main product in a sol-gel reaction followed by hydrothermal treatment from V2O5 precursors and primary amines. The material has a considerable large distance between the layers (ca. 3.5 nm), a wide inner (15-40 nm) and outer diameter (60-100 nm), and the open tube ends which are favorable for the magnesium ion insertion. VOx-NTs are a new kind of material with a unique nanostructured morphology, which can electrochemically insert/deinsert magnesium ions reversibly from the cyclic voltammogram. AC impedance (EIS) demonstrated that Mg2+ diffusion into the nanotubes is faster than polycrystalline V2O5 during intercalation Mg2+ into the cathodes. X-ray photoelectron spectroscopy (XPS) and X-ray powder diffraction (XRD) results gave the mechanism of Mg2+ insertion into the nanotubes, however, the specific capacity of the rechargeable magnesium is lower than that of lithium.