The electrochemical property of ZrFx-coated Li[Ni1/3Co1/3Mn1/3]O2 cathode material

Electrochemical and thermal properties of pristine and ZrFx-coated Li[Ni1/3Co1/3Mn1/3]O2 cathode materials are compared. The hydrothermal method is introduced for the fabrication of a uniform coating layer. The formation of a compact coating layer on the surface of pristine powder is observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). From TEM–EDS and XPS analysis, it is inferred that the coating layer is ZrOxFy (zirconium oxyfluoride) form. The coated Li[Ni1/3Co1/3Mn1/3]O2 electrodes have better rate capability and cyclic performance at high temperature compared with the pristine electrode. The thermal stability of the Li[Ni1/3Co1/3Mn1/3]O2 electrode is also enhanced by the ZrFx coating. Such enhancements are due to the presence of a stable coating layer, which effectively suppresses the chemical instability ascribed to surface reaction between electrode and electrolyte.