Improved cyclic stability of LiNi0.8Co0.1Mn0.1O2 via Ti substitution with a cut-off potential of 4.5 V

To improve the cyclic stability of LiNi 0.8 Co 0.1 Mn 0.1 O 2 cycled between 2.8 and 4.5   V vs. Li/Li + , titanium was incorporated into LiNi 0.8 Co 0.1 Mn 0.1 O 2 at various molar concentrations of 1, 2, 3 and 5% during the synthesis. The XRD , EDS and XPS analyses indicated that the titanium ions were effectively incorporated into the lattice of ternary oxides by occupying the transitional metal positions. Among the investigated molar concentrations, 2% Ti-substituted LiNi 0.8 Co 0.1 Mn 0.1 O 2 exhibited the best multifaceted performances with a relatively high capacity (205.7   mA   h   g −1 at 0.1   C), good rate capability (178.2   mA   h   g −1 at 1   C, 155.3   mA   h   g −1 at 5   C) and acceptable cyclic stability (86.9% at the 200th). The post-mortem analysis indicated that Ti substitution alleviates cracking from secondary particles to primary ones. This behavior is most likely due to the decreased ratio of volumetric deformation ( i.e. , 4.82% for the 2% Ti-substituted sample, which is 19.8% lower than that of the pristine one). Our results demonstrate that mechanical properties may play a crucial role in its long cyclability for use as a high-capacity ternary cathode.