Ultrafast Cathode Characteristics of Nanocrystalline-Li₃V₂(PO₄)₃/Carbon Nanofiber Composites

Abstract

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.