Structural and Electronic Properties of Lithiated SnO2. A Periodic DFT Study

The structural and electronic properties of the intercalation compound Li x SnO2 (x = 1/16, 1/8, 1/4, 1/2, 1) as well as the inherent diffusion mechanism of Li ion into the rutile SnO2 were investigated by means of periodic density functional calculations. Optimized structural parameters, cohesive e...

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Bibliographic Details
Published in:Journal of physical chemistry. C 2012-08, Vol.116 (30), p.16127-16137
Main Authors: Sensato, Fabrício R, Gracia, Lourdes, Beltrán, Armando, Andrés, Juan, Longo, Elson
Format: Article
Language:English
Subjects:
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Condensed matter: structure, mechanical and thermal properties
Diffusion in solids
Electron density of states and band structure of crystalline solids
Electron states
Equations of state, phase equilibria, and phase transitions
Exact sciences and technology
Fullerenes and related materials
intercalation compounds
General studies of phase transitions
Methods of electronic structure calculations
Order-disorder and statistical mechanics of model systems
Physics
Transport properties of condensed matter (nonelectronic)
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Summary:The structural and electronic properties of the intercalation compound Li x SnO2 (x = 1/16, 1/8, 1/4, 1/2, 1) as well as the inherent diffusion mechanism of Li ion into the rutile SnO2 were investigated by means of periodic density functional calculations. Optimized structural parameters, cohesive energies, electronic band structure, and density-of-states and Mulliken charges for the Li x SnO2 system at different Li ordering for each Li content are reported. The energetic profiles for the Li diffusion process into rutile SnO2 are also presented. Our calculation indicates substantial host distortion around intercalation sites, predominantly along the ab-planes. These deformations are found to be related to the soft B1g, Eu, A2g, and A1g vibrational modes of very low frequency and therefore easy to be achieved. The corresponding variation in volume monotonically increases with the Li concentration. Cohesive energies are consistent with continuous and reversible intercalation process. In lithiated SnO2, lithium is significantly ionized; however, the distribution pattern of the charge transferred from the lithium to the host is very dependent upon the ion concentration. By increasing the Li content, the relative amount of charge transferred to the Sn atoms decreases whereas the charge transferred to oxygen atoms increases. Lithium intercalation causes a chemical reduction of SnO2 and yields metallic properties. Effects induced by Li intercalation on the electronic band structures of SnO2 were assessed according to their origins, i.e., if they originate from lattice expansion or from chemical reduction. The energy difference between the valence-band maximum and conduction-band minimum of lithiated SnO2 decreases with increasing Li content. Lithium diffusion along the c-direction demands significantly lower activation energy than the energy required for diffusion along ab-planes. Energetic barriers related to the lithium diffusion into SnO2 were found to be dependent upon the Li content.
ISSN:1932-7447
1932-7455
DOI:10.1021/jp301677y