The article reports the first comparative experimental and computational study of the structure and lattice dynamics of four vanadium pentoxide polymorphs of interest for battery applications. A particular attention has been given to correlations between the polymorphs structure and their Raman spectra. Each structure has been optimized and its Raman spectrum (including frequencies and intensities) calculated for the first time, using the same level of theory.
Thanks to a remarkable agreement between the simulated and experimental spectra, a reliable description of all the observed spectral features is provided: Characteristic vibrations due to vanadyl V-O, V-O-V bridges, V-O inter-chain contacts are clearly identified in the different structures. Furthermore, this study has allowed assigning the low frequency Raman peaks observed in the Raman spectra of all polymorphs but usually disregarded up to now. These intense features are assigned to the existence of nonequivalent ladders in the structure, leading to different deformations of the inter-chain contacts. These findings are of utmost importance for future efficient use of Raman spectroscopy to probe the changes in V2O5-based materials under electrochemical operation.
Référence :