LiNi0.6Co0.4-zTizO2 - New cathode materials for Li-ion batteries

In this work series of LiNi0.6Co0.4-zTizO2 (z = 0.1, 0.2, 0.3) new cathode materials for lithium-ion batteries were studied in terms of their structural, transport and electrochemical properties in Li/Li+/LiNi0.6Co0.4-zTizO2 cells. The materials were synthesized by a high temperature solid-state reaction. XRD measurements with Rietveld analysis confirmed presence of a single phase with hexagonal crystal system with R-3 m space group for LiNi0.6Co0.4-zTizO2, and LiNi0.6Co0.4-zTizO2. Except for composition LiNi0.6Co0.4-zTizO2, which was refined by Rietveld method as cubic-close-packed structure. Electrical conductivity shows thermally activated character for all obtained cathode materials with very low activation energy in range from 0.001 eV to 0.062 eV. The highest values of electrical conductivity were recorded for LiNi0.6Co0.4-zTizO2 oxide. With increasing titanium content in LiNi0.6Co0.4-zTizO2 (z = 0.1, 0.2, 0.3) the increase of electrical conductivity was observed. Electrochemical studies performed for Li/Li+/LiNi0.6Co0.4-zTizO2 cell revealed enhancement of electrochemical performance after replacement of Co ions with 0.1 mol of Ti ions. The highest discharge capacity equal to 100 mAh/g at C/20 discharge rate, together with high stable voltage around similar to 4.2 V was achieved for LiNi0.6Co0.4-zTizO2 composition. Among considered cathode materials,LiNi0.6Co0.4-zTizO2 is the most promising for further development.