Figure 1: Structure of P2-Na0.66[Li0.22Ti0.78]O2.
From: A zero-strain layered metal oxide as the negative electrode for long-life sodium-ion batteries
(a) Synchrotron XRD pattern and Rietveld refinement of the as-prepared Na0.66[Li0.22Ti0.78]O2 sample. The red (black) line represents the experimental (calculated) data. The residual discrepancy is shown in blue. The refinement is preformed in the P63/mmc space group. The inset is the typical scanning electron micrograph of the as-prepared sample (scale bar is 10 μm). (b) Schematic illustration of the hexagonal Na0.66[Li0.22Ti0.78]O2 projected in a-c plane (left top is projected in a-b plane). Symbols A and B refer to the different oxygen layers. The green layer represents the Ti(Li)O2 layer and orange (2b site) or blue (2d site) bullets refer to Na ions that occupy the trigonal prismatic sites between two Ti(Li)O2 layers.
