Fast carrier diffusion via synergistic effects between lithium-ions and polarons in rutile TiO₂

Carrier mobility in titanium dioxide (TiO₂) systems is a key factor for their application as energy materials, especially in solar cells and lithium-ion batteries. Studies on the diffusion of Li-ions and polarons in rutile TiO₂ systems have attracted extensive attention. However, how their interaction affects the diffusion of Li-ions and electron polarons is largely unclear and related studies are relatively lacking. By using first-principles calculations, we systematically investigate the interaction between the intercalated Li-ions and electron polarons in rutile TiO₂ materials. Our analysis shows that the diffusion barrier of the electron polarons decreases around the Li-ion. The interaction between the Li-ions and polarons would benefit their synergistic diffusion both in the pristine and defective rutile TiO₂ systems. Our study reveals the synergistic effects between the ions and polarons, which is important for understanding the carrier properties in TiO₂ systems and in further improving the performance of energy materials.