Structure and Electrochemistry of Two-Electron Redox Couples in Lithium Metal Fluorophosphates Based on the Tavorite Structure

An electrochemical and structural study of the two-electron redox couple comprising the tavorite-type series of fluorophosphates Li1±x VPO4F (x = 0, 1) shows that both intercalation of LiVPO4F with Li (to give Li2VPO4F) and deintercalation (to give VPO4F) proceed by a two-phase mechanism. Structural models for each of the three phases were determined by Rietveld refinements of combined neutron and X-ray diffraction data of the isolated pure …