Improved electrochemical and thermal performances of layered Li[Li0.2Ni0.17Co0.07Mn0.56]O2 via Li2ZrO3 surface modification

Abstract

A conductive Li2ZrO3 layer is successfully coated on the surface of Li-rich layered cathode Li[Li0.2Ni0.17Co0.07Mn0.56]O2 to enhance its electrochemical performances. The crystal structures, electrochemical properties and thermal stabilities of the bare and coated materials are studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), electron diffraction spectroscopy (EDS), inductively coupled plasma (ICP), galvanostatic cycling, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). It has been found that the electrochemical performances of Li-rich cathode material are obviously improved by Li2ZrO3 surface modification. Especially, the 1 wt.% Li2ZrO3-coated material demonstrates the best cycling performance, with capacity retention of 89% after 50 cycles, much better than that of the pristine one, 64%. Intensive explorations indicate that the improved electrochemical properties can be attributed to the Li2ZrO3 surface layer, which not only stabilizes the cathode structure by decreasing the loss of oxygen, but also protects the Li-rich cathode material from side reaction(s) with the electrolyte and thus suppressing the fast growth of solid electrolyte interface (SEI) film on the surface of oxide particles.