A single-crystal study of the electrochemically Li-ion intercalated spinel-type Li4Ti5O12

Single crystals of Li4 + xTi5O12 were prepared by means of electrochemical Li-ion intercalation technique using parent Li4Ti5O12 single crystals. The obtained Li4 + xTi5O12 (x = 1.35) crystallizes in the cubic spinel-related type structure, space group Fd3̄m, and lattice parameters of a = 8.346(2) Å and V = 581.3(5) Å3 and Z = 8. The Li-ion intercalated sites were successfully determined to be both the 8a and 16c sites by using the difference Fourier synthesis map. The structure was determined by single-crystal X-ray structure analysis and refined to the conventional value of R = 3.7% for 132 independent observed reflections. The chemical composition has been determined to be Li5.35Ti5O12 from the result of site-population refinements. In addition, theoretical electron density distributions and total energy were calculated for three postulated compounds of “Li4.5Ti4.5O12” and “Li4.5 + xTi4.5O12” with x = 1.5 and 3.0.