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Persistent URL http://purl.org/net/epubs/work/39546
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Record Id 39546
Title Density-functional simulations of lithium intercalation in rutile
Abstract Density functional simulations of lithium intercalation into rutile structured titanium dioxide are presented. Full relaxation of structures for a wide range of insertion concentrations is used to identify the thermodynamically most stable configurations and Li-ion site preferences. The host lattice is found to undergo large deformations upon Li-insertion which can be related to the exitation of soft vibrational modes. The dominant screening interaction is found to be due to these elastic distortions of the lattice rather than to dielectric screening. This leads to highly anisotropic and concentration dependent effective Li-Li interactions, which are thus not amenable to empirical parameterisation. The anisotropic volume expansion is found to be largely due to the increase in the radii of reduced Ti-ions as they accomodate charge donated to the lattice. The computed open circuit voltage reproduces the characteristic features of experimental discharge curves at elevated temperature. The computed Li-ion energy surfaces reveal highly anisotropic diffusion. A new model of Li-intercalation is proposed which takes account of both the thermodynamic and kinetic properties computed here. This model is used to resolve apparent contradictions in the current interpretation of the measured OCV and its dependence on temperature. Predicited changes in the electronic structure and their relationship to the interaction between structural, charge and spin degrees of freedom are discussed in detail.
Organisation CCLRC , CSE , CSE-CMSG
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Language English (EN)
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Journal Article Phys Rev B (2002): 235423. doi:10.1103/PhysRevB.65.235423 2002