Abstract:LiVPO₄F/C-based material was prepared by heating a precursor, which was obtained through ball milling with slurry of H₂C₂O₄·2H₂O, NH₄H₂PO₄, NH₄VO₃ and LiF. In this process, H₂C₂O₄·2H₂O was used as a reducing agent as well as carbon source. The properties of the precursor and the prepared sample were characterized by TG-DTA, XRD, SEM, TEM and C-S analysis. XRD analysis shows that the precursor is amorphous and the prepared LiVPO₄F sample coexists with Li₃V₂(PO₄)₃, as well as a small amount of V₂O₃. Homogeneous powders with an average particle size of 2 μm are observed by TEM. HRTEM image shows that the crystal particles are coated by amorphous carbon uniformly, with a coating layer of about 2 nm. The synthesized material shows the specific discharge capacities of 151.3 and 102.5 mA·h/g at 0.1C and 10C respectively, in the voltage range of 3.0-4.4 V, and it keeps 90.4% of initial discharge capacity at 10C after 50 cycles. V³⁺/V⁴⁺ redox peaks corresponding to both LiVPO₄F and Li₃V₂(PO₄)₃ are seen clearly in the CV curve.

Key words: lithium ion battery; LiVPO₄F; ball milling; cathode material; carbon coating