How does the Li-distribution in the 16d sites determine the stability of A₃(Li,Ti₅)O₁₂ (A = Li and Na)?

Abstract

Li3(Li,Ti5)O12 (LTO) is a stable and safe negative electrode material for Li-ion batteries, and its Na substitute Na3(Li,Ti5)O12 (NTO) is a counterpart for the Na-ion battery.

Polaron-Assisted Charge Transport in Li-Ion Battery Anode Materials

“…In order to study Li migration, we choose a diffusion path connecting two of the stable tetrahedral sites (the 8a Wyckoff position in the Fd 3̅ m spinel symmetry , ) I and F shown in Figure . Within this simulation cell, all tetrahedral sites are occupied by lithium ions, as would also be expected for non-Li-deficient LTO.…”

Different Oxygen Desorption Durabilities of Lithium Titanium Oxides as Confirmed by Transmission Electron Energy-Loss Spectroscopy Analysis of Li4Ti5O12 and β-Li2TiO3 Biphase Specimens

“…The 16d sites in Li 4 Ti 5 O 12 contain two atoms (Li or Ti) randomly; hence, to preserve its stoichiometry, 1 × 1 × 3 supercells with optimized Li compositions should be used. − The unit cell was used to estimate the total energy of Li 2 TiO 3 . The reaction energies of Li, Li 2 O, Ti, and TiO 2 were calculated.…”

Properties of spinel-type Ti–Li–M composite oxides (M = Li, Na, Cu, and Ag) predicted by density functional theory

“…The O-displacements were confirmed by theoretical calculations such as density functional theory (DFT). 33 According to DFT calculations in a previous study, 34 although there is no significant difference in the electronic structures and bandgaps near the Fermi energy region between LTO and NTO, there is a clear difference in the Rydberg orbital regions of Li and Na (8 eV above the Fermi energy). The difference in the high-energy region has also been experimentally confirmed to be a difference in the electron energy loss spectra of LTO and NTO, 29 which is caused by the difference in interactions between the Ti-O framework and the 8a site cations.…”

“…The smallest supercell model that achieves the chemical ratio is three times the size of the unit cell, and a 1 Â 1 Â 3 cell is typically used. [32][33][34][35][37][38][39][40] The Li + site at the 16d site in the 1 Â 1 Â 3 cell has already been optimised, 33,39,40 and the stability of the spinel titanium oxide framework for Li + placement has also been verified. 33 In this study, we adopted the arrangement of the 16d site Li + optimised in a previous study.…”

“…22,[29][30][31] Therefore, studies have been conducted on the physical properties and stability of Ti-O frameworks in spinel titanium oxides by comparing LTO and NTO. 22,29,[32][33][34][35] Synchrotron Radiation X-ray diffraction analysis showed that the position of O anions in NTO is displaced compared to LTO. 29 It is appropriate to fit the O anion position of NTO as the 192i site rather than the 32e site.…”