Role of zirconium dopant on the structure and high voltage electrochemical performances of LiNi0.5Co0.2Mn0.3O2 cathode materials for lithium ion batteries

The severe capacity fading and poor rate performance under high voltage of LiNi0.5Co0.2Mn0.3O2 are the vital barriers for their large scale application. In order to solve above issues, zirconium doped LiNi0.5Co0.2Mn0.3O2 materials were prepared by solid state method. The effects of the zirconium content on the structure and electrochemical properties of Li(Ni0.5Co0.2Mn0.3)1-xZrxO2 were extensively studied. Though the zirconium doped samples delivered lower initial capacities, the cycling stability are dramatically enhanced. Notably, Li(Ni0.5Co0.2Mn0.3)0.99Zr0.01O2 showed a capacity retention of 83.78% at 1C after 100 repeated cycle in a high voltage of 4.6 V, while that of bare sample remains only 69.35%. Moreover, the rate capability of Li(Ni0.5Co0.2Mn0.3)0.99Zr0.01O2 is also greatly reinforced especially at high current density. The improved electrochemical performances could be ascribed to the less cation mixing degree, better lithium transportation kinetic and lower impedance, which were confirmed by Rietveld refinement, X-ray photoelectron spectroscopy and electron impedance spectroscopy.