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 °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, ⁶Li and ³¹P 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.