The preparation of NaV1−xCrxPO4F cathode materials for sodium-ion battery

The key to development of sodium-ion battery is the preparation of cathode/anode materials. Cr doped NaV1−xCrxPO4F (x = 0, 0.04, 0.08) were prepared by the high temperature solid-state reaction for the application of cathode material of sodium-ion batteries. The structures and morphologies of the cathode materials were characterized by Flourier-infrared spectra (FT-IR), X-ray diffraction (XRD) and scanning electron microscope (SEM). The effects of Cr doping on performances of the cathode materials were analyzed in terms of the crystal structure, charge–discharge curves and cycle performances. The results showed that the as-prepared Cr-doped materials have a better cycle stability than the un-doped one, an initial reversible capacity of 83.3 mAh g−1 can be obtained, and the first charge–discharge efficiency is about 90.3%. In addition, it was also observed that the reversible capacity retention of the material is still 91.4% in the 20th cycles.