Theoretical investigation of migration pathways for Li diffusion in h-LiTiS 2

Mazharul M. Islam, Thomas Bredow

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Lithium diffusion in highly lithiated hexagonal titanium disulphide (h-Li xTiS 2, x = 0.88, 1.0) is investigated theoretically with periodic quantum-chemical methods. The calculated lithiation energies confirm that Li preferentially occupies the octahedral site rather than the tetrahedral site. Surprisingly, uncorrected density-functional theory (DFT) methods give better agreement with experiment for the structural parameters than the dispersion-corrected DFT-D approaches. Among the considered point defects, V Li, V Ti, and T ii, Li point defects are thermodynamically preferred in h-Li xTiS 2. A moderate relaxation is observed for the atoms surrounding the Li defect or Ti defect site, whereas a pronounced relaxation of the nearest neighboring atoms of a Ti Frenkel defect occurs. Competing pathways for Li diffusion in h-Li xTiS 2 are investigated using the climbing-image Nudged-Elastic-Band (cNEB) approach. Li + ions can migrate within the crystallographic ab plane either in a direct pathway through shared edges of neighboring octahedra or via vacant tetrahedral sites. The possibility of three-dimensional Li + diffusion along the c direction is investigated via inclusion of Ti point defects and Ti Frenkel defects.

Original languageEnglish
Pages (from-to)449-459
Number of pages11
JournalZeitschrift fur Physikalische Chemie
Volume226
Issue number5-6
DOIs
Publication statusPublished - 1 Jun 2012

Keywords

  • Activation energy
  • Dispersion corrected DFT
  • Frenkel defect
  • Li ion diffusion
  • Lithium titanium disulphide
  • Point defects
  • Relaxation

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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