Dresden 2006 – scientific programme

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DF: Dielektrische Festkörper

DF 3: Poster Session

DF 3.18: Poster

Monday, March 27, 2006, 09:30–17:00, P1

Effect of anion substitution on Li diffusion in Li_xTiS_2−ySe_y: Quantum-chemical calculations — •T. Bredow¹, M. Wilkening², S. Indris², P. Heitjans², J. Wontcheu³, and W. Bensch³ — ¹Hannover University, Theoretical Chemistry, D-30167 Hannover — ²Hannover University, Institute of Physical Chemistry and Electrochemistry, D-30167 Hannover — ³University of Kiel, Institute of Inorganic Chemistry, D-24098 Kiel

The Li intercalation of titanium chalcogenides TiS₂, TiSSe and TiSe₂ is investigated quantum-chemically at density functional level in combination with a crystalline orbital approach based on atom-centered basis functions. Periodic supercells are used to model the Li_xTiS_2−ySe_y system. The electronic structure of the intercalation compounds, the electric field gradients at the Li lattice positions, and the activation barriers for elementary steps of the Li ion migration are calculated and compared to experimental results obtained by NMR spectroscopy. A strong dependence of both electric field gradient and migration barrier on the local environment of the Li ions is observed. The activation energy is similar for TiS₂ and TiSe₂ host systems but differs for TiSSe. Supported by the DFG (SPP 1136).