Theoretical study of Li migration in lithium-graphite intercalation compounds with dispersion-corrected DFT methods

Sascha Thinius, Mazharul M. Islam, Paul Heitjans, Thomas Bredow

Research output: Contribution to journalArticlepeer-review

76 Citations (Scopus)

Abstract

Structural, energetic, electronic, and defect properties of lithium-graphite intercalated compounds (LiC6n (n = 1, 2)) are investigated theoretically with periodic quantum-chemical methods. Calculated properties obtained with a gradient-corrected density functional theory (DFT) method and a dispersion-corrected DFT method (DFT-D3-BJ) are compared. The DFT-D3-BJ method gives better agreement with experiment for the structural parameters and Li intercalation energy compared to the uncorrected DFT approach, showing that interlayer interactions due to the van der Waals forces play an effective role in graphite and LiC6n compounds. In agreement with the literature, the calculated density of states (DOS) show that graphite is metallic with a low DOS at the Fermi level, whereas LiC6n compounds have a high DOS at the Fermi level. Between the considered point defects, V Li and Lii, the energy needed to form Li point defects is smaller if solid Li is used as reference. A moderate relaxation is observed for the atoms surrounding the Li defect. Competing pathways for Li diffusion in LiC6n compounds are investigated using the climbing-image nudged elastic band approach. Two different mechanisms for Li diffusion are observed, the vacancy mechanism and the Frenkel mechanism. For both cases, Li migration pathways along the ab plane and along the c crystallographic axis are investigated. A large activation barrier along the c crystallographic direction indicates that Li does not diffuse in the c direction. The calculated activation barriers for Li diffusion in the ab plane are consistent with previous experimental investigations.

Original languageEnglish
Pages (from-to)2273-2280
Number of pages8
JournalJournal of Physical Chemistry C
Volume118
Issue number5
Early online date22 Jan 2014
DOIs
Publication statusPublished - 6 Feb 2014

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Fingerprint Dive into the research topics of 'Theoretical study of Li migration in lithium-graphite intercalation compounds with dispersion-corrected DFT methods'. Together they form a unique fingerprint.

Cite this