Ultrafast cathode characteristics of nanocrystalline-Li₃V₂(PO₄)₃/carbon nanofiber composites

Anisotropically grown Li₃V₂(PO₄)₃ nanocrystals, which are highly dispersed and directly impregnated on the surface of a carbon nanofiber (CNF), were successfully synthesized via a two-step synthesis process: i) precipitation of nanoplated V₂O₃ precursors (20-200 nm); ii) transformation of the V₂O₃ precursor into Li₃V₂(PO₄)₃ nanoplates without size change. The direct attachment of the Li₃V₂(PO₄)₃ nanocrystals to the carbon surface improves the electronic conductivity and Li⁺ diffusivity of the entire Li₃V₂(PO₄)₃/CNF composite, simultaneously producing a mesoporous network (pore size of approximately 10 nm) that acts as an electrolyte reservoir owing to the pillar effect of the impregnated Li₃V₂(PO₄)₃ crystals. This ideal Li₃V₂(PO₄)₃/CNF nanostructure enabled a 480C rate (7.5 seconds) discharge with 83 mA h g^-1, and 69% of capacity retention at the slowest discharge rate (1C). Such an ultrafast charge-discharge performance opens the possibility of using Li₃V₂(PO₄)₃ as a cathode material for ultrafast lithium ion batteries with a stable cycle performance over 10,000 cycles at a 10C rate, maintaining 85% of the initial capacity.