Carbon nanocage supported synthesis of V2O5 nanorods and V2O5/TiO2 nanocomposites for Li-ion batteries

Abstract

We present the facile synthesis of crystalline V₂O₅ nanorods and V₂O₅/TiO₂ nanocomposites structures by a carbon nanocage (CNC)-assisted growth process, using vanadium triisopropoxide oxide and titanium isopropoxide precursors in air at 500 °C. The diameters of the resultant V₂O₅ nanorods ranged between ∼10 and 70 nm, while the crystalline V₂O₅/TiO₂ nanocomposite structures adopted a unique morphology, due to both crystallisation and templating processes, with V₂O₅ adopting small-diameter nanowire and nanorod morphologies surrounded by sub-30 nm TiO₂ nanoparticles. The V₂O₅ nanorods and V₂O₅/TiO₂ nanocomposites were characterised by electron microscopy and X-ray diffraction techniques and subsequently reviewed as positive Li-ion electrodes. The phase-pure V₂O₅ nanorod structures exhibited appreciable Li⁺ storage properties over the potential range of 2.0–4.0 V vs. Li/Li⁺, displaying capacities of up to 288 mA h g⁻¹ with appreciable cyclic behaviour at test rates of up to ∼1 C. The crystalline V₂O₅/TiO₂ nanocomposite structures displayed similar Li⁺ storage properties, however, increasing molar fractions of TiO₂ led to a decline in the overall capacity versus the single-phase V₂O₅ counterparts. Interestingly, the Li⁺ insertion behaviour of the V₂O₅/TiO₂ nanocomposite displayed character more-typical of amorphous V₂O₅, which was ascribed to a structural buffering effect of the inactive TiO₂ phase.