Exploration of layered-type pseudo four-component Li-Ni-Co-Ti oxides

A series of layered-type pseudo four-component Li-Ni-Co-Ti oxides were prepared to explore optimal cathode materials for a lithium-ion secondary battery. The new layered-type compounds were prepared using a combinatorial material-preparation system based on electrostatic spray deposition (the “M-ist Combi” system), and combinatorial powder X-ray diffraction. The composition region of the new compounds (Li_α(Ni_xCo_yTi_z)O₂ (α∼1, 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, z∼0.2, x + y + z = 1.0)) was found to be wider than the composition region previously reported (LiNi_0.8−yCo_0.2Ti_yO₂ (0 ≤ y ≤ 0.1)).     

Über die Einheitengruppe eines endlichen Ringes

Ohne ZusammenfassungDiese Arbeit wurde in Proc. of the Imperial Academy of Japan5, Nr. 3, vorangezeigt.     

On the Origin of the Non-Arrhenius Na-ion Conductivity in Na3OBr

The sodium-rich antiperovskites (NaRAPs) with composition Na₃OB (B=Br, Cl, I, BH₄, etc.) are a family of materials that has recently attracted great interest for application as solid electrolytes in sodium metal batteries. Non-Arrhenius ionic conductivities have been reported for these materials, the origin of which is poorly understood. In this work, we combined temperature-resolved bulk and local characterisation methods to gain an insight into the origin of this unusual behaviour using Na₃OBr as a model system. We first excluded crystallographic disorder on the anion sites as the cause of the change in activation energy; then identified the presence of a poorly crystalline impurities, not detectable by XRD, and elucidated their effect on ionic conductivity. These findings improve understanding of the processing-structure-properties relationships pertaining to NaRAPs and highlight the need to determine these relationships in other materials systems, which will accelerate the development of high-performance solid electrolytes.