Synthesis of Li 4 V(PO 4 ) 2 F 2 and 6,7Li NMR studies of its lithium ion dynamics

A single phase, well-crystallized Li4V(PO4)2F2/carbon nanocomposite has been prepared by an optimized solid-state route via oxidation of Li5V(PO4)2F2. The Li4V(PO4)2F2 composition exhibits lattice parameters close to those of the oxidized parent (a = 6.898 Å, b = 10.673 Å, c = 9.977 Å; β = 87.84°; V = 734.0 Å3). 1D 6Li solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR) studies identified which of the six lithium ions are …