Concentration-Dependent Ordering of Lithiated Amorphous TiO₂

We present the results of molecular dynamics simulations on the disorder–order transition of highly lithiated amorphous TiO₂. Our simulations suggest the presence of a threshold Li concentration above which long-range order gradually sets in for the fully lithiated amorphous TiO₂ at high temperatures. Our results indicate a clear correlation between the diffusional characteristics of Li, Ti, and O and the extent of ordering, both of which depend on Li concentration. Analyses of the changes in the system’s configurational energy, the pair correlation entropy, and various orientational bond-order parameters as a function of simulation time suggest a structural evolution from an amorphous to an ordered cubic TiO₂ structure, providing molecular-level explanation of the recent experimental observations on this unique lithium-induced phase transitions. The structural stability under extreme pressure conditions and the Li diffusivity in the ordered structure are also reported for assessing its potential to be used as a metal oxide anode for Li-ion batteries