Interstitial lithium doping in SrTiO₃

Strontium titanate (SrTiO3) has received much attention due to its wide range of potential applications including in electrochemical devices such as solid oxide fuel cells and capacitors. The stability and safety features of SrTiO3 led to the development of promising electrodes for Li-ion batteries. Here, we use density functional theory simulations to examine the incorporation of lithium from its gas-phase and bulk forms. The results show that a single Li atom is thermodynamically stable in bulk SrTiO3 with respect to its gas-phase and slightly unfavourable compared to its bulk. Multiple Li incorporation up to six is also considered and the incorporation is exoergic with respect to both gas-phase and bulk forms. Charge analysis confirmed the presence of Li+ ions in the lattice. Li incorporation turns the insulating nature of SrTiO3 into metallic and non-magnetic into magnetic. Lithium incorporation facilitates the formation of Sr, Ti and O vacancies. The loss of Li2O is exoergic suggesting that oxygen vacancy mediated-self diffusion will be promoted.