Multifunctional modification of Li[Ni0.5Co0.2Mn0.3]O2 with NH4VO3 as a high performance cathode material for lithium ion batteries

Li[Ni0.5Co0.2Mn0.3]O2 material was treated with NH4VO3 at 400 °C for 3 h Li3VO4 coating layer was formed during the calcination by using lithium residues on the material surface as raw materials. XRD results showed the NH4VO3 modified material had less Li+/Ni2+ cation mixing degree and confirmed some vanadium doped into the crystal lattice. Electrochemical studies indicated the modified material exhibited excellent lithium ion diffusion coefficient, superior cycle performance and improved rate capability compared with those of the bare material. The NH4VO3 modified sample maintains 156.7 mA h g−1 with 87.8% capacity retention after 100 high-voltage cycles (with 4.6 V charge cut-off) at 1 C. While, for the bare sample, the value is only 131.3 mA h g−1 with 75.5% capacity retention. The enhanced electrochemical performance can be ascribed to the removal of lithium residues, the doping of vanadium ion and the lithium ion conductive Li3VO4 coating layer. On the basis of these results, Li3VO4 coated Li[Ni0.5Co0.2Mn0.3]O2, prepared by the direct reaction with NH4VO3, can be used as a promising cathode material for Li-ion batteries.