| dc.description.abstract | Titanium dioxide has recently attracted focus as a potential anode material in lithium-ion rechargeable batteries (LiBs) because of the low cost, abundant source, light weight, safety, and high theoretical capacitance. However, the practical application of TiO2 is restricted to its poor electronic conductivity and inefficient lithium diffusion. Previous studies show “hydrogenation processes” can remove the oxygen atoms from TiO2 and create oxygen vacancies, which may improve electronic conductivity and facilitate lithium mass transport to enhance anode material
performances.
In this work, three most common polymorphs of TiO2 as lithium-ion battery anode materials: anatase, rutile and TiO2(B) have been modeled and first-principles study based on density functional theory (DFT) calculations have been employed to investigate the intercalation and diffusion behavior of lithium in TiO2 with/without an oxygen vacancy at dilute lithium concentrations. Total energies of possible intercalation sites were first calculated to find out the favorable site among the three phases. Furthermore, all lithium diffusion pathways from
one stable site to another stable site were examined by climbing image nudged elastic band method. To compare the effect of oxygen vacancy on lithium diffusion mechanism, energy
barriers of pristine TiO2 and oxygen-defective structures have been calculated. In addition, the electronic structure of TiO2 with oxygen vacancy was calculated in comparison with pristine TiO2. The results indicate that among three polymorphs, TiO2(B) may the better choice for
oxygen vacancy process because its intercalation energy is the most stable one, it has lower diffusion energy barrier change, and also show narrowed band gap after oxygen vacancy introduction. | en_US |