The influence of nanostructure size on V2O5 electrochemical properties as cathode materials for lithium ion batteries

Abstract

In this paper, V₂O₅ nanostructures with a size depending on the annealing temperature are successfully synthesized by a sol–gel method. The crystal structure and morphology of the samples are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), selected area electron diffraction (SEAD) and scanning electron microscopy (SEM), respectively. Electrochemical testing such as discharge–charge cycling (CD) and cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are employed in evaluating their electrochemical properties as cathode materials for lithium ion batteries. One-dimensional nanostructures are successfully synthesized with the same structure, composition and similar shape. The results reveal that for one-dimensional nanostructures, next to the thickness which must be as small as possible, the length of the nanocrystals is crucial and should be above 2 μm. The longer nanostructures obtained at 650 °C deliver a discharge specific capacity of 281 mA h g⁻¹ at a current rate of C/5 which is over 95.5% of the theoretical capacity for two Li⁺ ion intercalation (294 mA h g⁻¹) within a voltage window of 2.0–4.0 V.