LiVPO4F/Li3V2(PO4)3 nanostructured composite cathode materials prepared via mechanochemical way

Single-phase LiVPO4F and LiVPO4F/Li3V2(PO4)(3) nanostructured composite cathode materials were prepared by heating of the VPO4 + LiF mechanochemically activated mixture to 700 A degrees C and subsequent quick or slow cooling to room temperature, respectively. The formation of the composites was proved by a combination of different physico-chemical methods, including XRD, FTIR, Li-6 and P-31 NMR, SEM, TEM, and HRTEM. It has been shown that in the composites LiVPO4F and Li3V2(PO4)(3) nanocrystals well inset into each other resulting in the nanodomain composite formation. Charge-discharge curves of the composites have a sloping profile both in the high-voltage (3.0-4.5 V) and in the low-voltage (1.3-2.5 V) ranges, noticeably different from plateaus for a phase-pure LiVPO4F, thus indicating a probable change of a two-phase regime of lithium intercalation for a single-phase one. Enhanced rate capability of the LiVPO4F/Li3V2(PO4)(3) composites is associated with their microstructure and high ionic conductivity of Li3V2(PO4)(3).