Enhanced electrochemical performance of electrospun V₂O₅ fibres doped with redox-inactive metals

The structural and electrochemical effects of electrospun V₂O₅ with selected redox-inactive dopants (namely Na⁺, Ba²⁺ and Al³⁺) have been studied. The electrospun materials have been characterised via a range of analytical methods including X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area measurements and scanning and transmission electron microscopy. The incorporation of dopants in V₂O₅ was further studied with computational modelling. Structural analysis suggested that the dopants had been incorporated into the V₂O₅ structure with changes in crystal orientation and particle size, and variations in the V⁴⁺ concentration. Electrochemical investigations using potentiodynamic, galvanostatic and impedance spectroscopy analysis showed that electrochemical performance might be dependent on V⁴⁺ concentration, which influenced electronic conductivity. Na⁺- or Ba²⁺-doped V₂O₅ offered improved conductivities and lithium ion diffusion properties, whilst Al³⁺ doping was shown to be detrimental to these properties. The energetics of dopant incorporation, calculated using atomistic simulations, indicated that Na⁺ and Ba²⁺ occupy interstitial positions in the interlayer space, whilst Al³⁺ is incorporated in V sites and replaces a vanadyl-like (VO)³⁺ group. Overall, the mode of incorporation of the dopants affects the concentration of oxygen vacancies and V⁴⁺ ions in the compounds, and in turn their electrochemical performance. [Figure not available: see fulltext.].