Surface Modification of Li1.6(Fe0.2Ni0.2Mn0.6)O2.6 by V2O5- Coating

We presented a method to improve the first discharge capacity and the cycling performance of Li1.6(Fe0.2Ni0.2Mn0.6)O2.6 which was synthesized by a coprecipitation-hydrothermal-calcinations method and coated by a V2O5 layer on the surface of Li1.6(Fe0.2Ni0.2Mn0.6)O2.6. The crystal structure and the charge/discharge performance of Li1.6(Fe0.2Ni0.2Mn0.6)O2.6 were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), inductively coupled plasma (ICP) and electrochemical performance measurement. Results show that V2O5 exists only on the surface, and has no effect on the crystal structure; the Li1.6(Fe0.2Ni0.2Mn0.6)O2.6 coated with V2O5 exhibits better first discharge capacity than the bared Li1.6(Fe0.2Ni0.2Mn0.6)O2.6. The electrochemical tests demonstrate that Li1.6(Fe0.2Ni0.2Mn0.6)O2.6 coated with 3 wt% V2O5 shows the best electrochemical performance with the discharge capacity 200.3 mAh/g after 50 cycles, while the bared sample has 194.0 mAh/g only. CV results indicate that the V2O5 coating can suppress the phase transitions and prevent the surface of cathode materials from the direct contact with the electrolyte.