Phase change effect on the structural and electrochemical behaviour of pure and doped vanadium pentoxide as positive electrodes for lithium ion batteries

Electrospun ceramic oxide fibers find myriad uses as energy materials such as in battery electrodes and vanadium oxides are one such family of materials. In this study, the structural and energy storage properties of electrospun vanadium pentoxide are compared to approximately 10 at% barium and titanium-doped equivalents. The vanadium pentoxide was doped in order to improve its electrochemical performance. The materials are characterised using powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller measurements, transmission electron microscopy and potentiostatic and galvanostatic analysis. X-ray diffraction analysis showed that each dopant has a critical effect on lattice distortions whilst showing no influence over the overall crystal structure, which is unusual for such large dopant amounts. The doped materials show better cyclability and higher efficiencies than the pure equivalent. Ex-situ X-ray diffraction measurements show detrimental phase changes within undoped V₂O₅ whereas the titanium-doped V₂O₅ predominantly remains as α-V₂O₅ after the first cycle.