Study of LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2 Coated with Li_2ZrO_3 Nanolayers in All-Solid-State Lithium Ion Batteries

摘要

The Li2ZrO3 nanolayer was coated over LiNi0.6Co0.2Mn0.2O2 cathode material (NCM) to produce all-solid-state lithium ion batteries and their enhanced electrochemical properties were determined. To relieve interfacial resistance resulting from insufficient contact, a Li2ZrO3 nanolayer is a suitable cathode coating agent because it can block corrosive species and decrease contact loss, along with elimination of the space-charge layer. All-solid-state cells using Li2ZrO3-coated NCM material showed higher capacity than pristine NCM. X-ray diffraction patterns showed the same peak separations and lattice parameters as pristine material. Scanning electron microscopy and transmission electron microscopy images obtained with electron dispersive spectroscopy mapping confirmed homogeneous coating with a uniformly thick Li2ZrO3 layer of around 5 nm. X-ray photoelectron spectroscopy revealed that the surface of NCM had two different O1s peaks, with a Zr-O peak, and Ni, Co, Mn, and Zr peaks. Electrochemical studies on pristine and Li2ZrO3-coated NCM materials were conducted using electrochemical impedance spectroscopy with galvanostatic cycle performances by constructing an all-solid-state cell. The impedance spectra showed relieved interfacial resistance with low polarization as coating agent was added. Notably, the 4 wt.% Li2ZrO3-coated NCM exhibited capacity retention of 81% at a current density of 0.12 mA/cm(2) after 30 cycles, while that of the pristine cell hadunstable cycle performance and a low capacity retention of 69 percent. Thus, the Li2ZrO3-coated NCM material exhibited potential for all-solid-state batteries requiring high power or stable application.