Improved high voltage electrochemical performance of Li2ZrO3-coated LiNi0.5Co0.2Mn0.3O2 cathode material

Abstract

The use of Li2ZrO3 as an effective coating to enhance the cycling performance and rate capability of LiNi0.5Co0.2Mn0.3O2 cathode material under high cut-off voltage of 4.6 V has been demonstrated. The structural and morphological characteristics of the bare and coated samples were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Electrochemical studies on bare and Li2ZrO3-coated LiNi0.5Co0.2Mn0.3O2 samples were conducted using galvanostatic charge–discharge, cyclic voltammetry and electrochemical impedance spectroscopy by constructing a lithium half-cell. It has been found that the high cut-off voltage electrochemical performances of LiNi0.5Co0.2Mn0.3O2 cathode material are obviously improved by Li2ZrO3 surface modification. Notably, the 1 wt.% Li2ZrO3-coated sample exhibits a capacity retention of 87.1% at 1C after 100 cycles, while that of bare one is 72.8%. The cyclic voltammograms and impedance spectra results shown that the Li2ZrO3 coating reduced the polarization and improved the electrochemical activity of cathode. DSC tests reveal that the Li2ZrO3 coating layer also helps in enhancing the thermal stability of LiNi0.5Co0.2Mn0.3O2 cathode. Thus the Li2ZrO3-coated LiNi0.5Co0.2Mn0.3O2 indicates potential lithium ion batteries for high power applications even at high operating voltage.