Ab initio Studies on Li4+xTi5O12 Compounds as Anode Materials for Lithium-Ion Batteries

The structural and electronic properties of Li4+xTi5O12 compounds (with 0≤x≤6)—to be used as anode materials for lithium‐ion batteries—are studied by means of first principles calculations. The results suggest that Li4Ti5O12 can be lithiated to the state Li8.5Ti5O12, which provides a theoretical capacity that is about 1.5 times higher than that of the compound lithiated to Li7Ti5O12. Further insertion of lithium species into the Li8.5Ti5O12 lattice results in a clear structural distortion. The small lattice expansion observed upon lithium insertion (about 0.4 % for the lithiated material Li8.5Ti5O12) and the retained [Li1Ti5]16dO12 framework indicate that the insertion/extraction process is reversible. Furthermore, the predicted intercalation potentials are 1.48 and 0.05 V (vs Li/Li+) for the Li4Ti5O12/Li7Ti5O12 and Li7Ti5O12/Li8.5Ti5O12 composition ranges, respectively. Electronic‐structure analysis shows that the lithiated states Li4+xTi5O12 are metallic, which is indicative of good electronic‐conduction properties. Intercalation compounds: The structural and electronic properties of Li4+xTi5O12 compounds (where 0≤x≤6) are studied by using first principles calculations. The theoretical capacity of the lithiated Li8.5Ti5O12 species (see structure) is about 1.5 times higher than that of the normal Li7Ti5O12 compound. The lithiated states are metallic and exhibit good conducting properties.