Résumé
Vanadium fluoride phosphates are highly intriguing due to their diverse crystal structures, which significantly influence their electrochemical properties, making them favorable candidates for Li-ion and post Li-ion battery applications. In this study, high-energy resolution fluorescence-detected X-ray absorption near-edge structure (HERFD-XANES) spectroscopy and X-ray emission spectroscopy (XES) are combined to describe and understand the distinctive features of Tavorite-type LiVPO4F and KTP-type KVPO4F, along with their deintercalated homeotypic phases. The HERFD-XANES spectra, featuring the 1s2p resonant inelastic X-ray scattering (RIXS) process at the pre-edge region, provide detailed information on the local structure, while a thorough interpretation of the XES signals, including Core-to-Core (CtC) Kα and CtC Kβ, offers complementary information about local structures and oxidation states, respectively. Furthermore, the occupied and unoccupied electronic states close to the Fermi level are described by combining the information from the XES Valence-to-Core (VtC) Kβ2,5 emission line and the HERFD-XANES pre-edge, respectively. The thorough understanding of these spectral signatures is made possible by the application of ab initio calculations. Overall, this comprehensive analysis of both local geometric and electronic structures provides valuable insights into these materials with distinct crystal structures which are applied as alkali ion positive electrodes.