An Ab Initio Study of Lithium Diffusion in Titanium Disulfide Nanotubes

Abstract

Using density functional theory (DFT), we have investigated the mobility and insertion potential of Li on single-walled TiS2 nanotubes as a function of radius. To explore large radii, the nanotube surface is modeled as a curved surface. For small tubes, for which DFT calculations are practical on the complete tube, we find that strain energies, voltages, and activation barriers calculated with the curved surface method are nearly the same as those calculated with a full nanotube. Our results show that, for the range of nanotube radii that are seen experimentally (approximately 50−250 Å), Li diffusion on the nanotube surface is very fast and similar to diffusion on a flat surface. In general, the activation barrier for Li diffusion is 200 meV smaller on the surface than in the bulk, which could result in an improved mobility of Li by a factor of 3000 at room temperature. The effect of tube radius on the Li insertion voltage and migration energy can be explained by the electrostatic repulsion between Li and Ti and by the relaxation of the S atoms.

First-principles investigations of vanadium disulfide for lithium and sodium ion battery applications

“…19,20 The linear interpolation was applied between the initial and nal states of the ion diffusion path with nine and eight intermediate images for hexagonal (H) monolayer and trigonal (T) bulk VS 2 , respectively. 19,20 The linear interpolation was applied between the initial and nal states of the ion diffusion path with nine and eight intermediate images for hexagonal (H) monolayer and trigonal (T) bulk VS 2 , respectively.…”

Polygonal model for layered inorganic nanotubes

“…[28][29][30][31][32]63 Bulk TiS 2 has long been studied as an intercalation compound and TiS 2 nanotubes have shown the ability to store hydrogen and lithium. Bulk TiS 2 forms the CdI 2 -1T structure which consists of layers of Ti atoms octahedrally coordinated by S atoms.…”

“…Bulk TiS 2 forms the CdI 2 -1T structure which consists of layers of Ti atoms octahedrally coordinated by S atoms. 63,65,66 These triple layers ͑S-Ti-S͒ are separated by a Van der Waals gap and stacked such that the titanium atoms project on top of each other. This triple layer is the basic structural unit of TiS 2 layered nanotubes.…”

Theoretical Investigation of Migration Pathways for Li Diffusion in h-LiTiS 2

“…Therefore, in recent years, the cation diffusion in h-Li x TiS 2 has been the topic of numerous investigations, both experimentally [9][10][11][12][13] and theoretically [14][15][16][17]. By 7 Li solid state NMR investigation, Prigge et al [9] have observed a fast Li + mobility in h-Li x TiS 2 with measured activation energies of 0.25 eV and 0.20 eV for x = 0.75 and 1.0, respectively.…”