Mechanism of Li+/Electron Conductivity in Rutile and Anatase TiO2 Nanoparticles

Concurrent Li ion and electron conductivity in rutile and anatase TiO2 nanoparticles was studied using multiscale simulations. We show that charge transport in titania nanoparticles is determined by the competition of charge redistribution toward the particle boundaries and constant Li+ and electron fluxes. In nanoparticles smaller than the Debye length, the constant flux prevails and the conductivity has a dual ionic and electronic character, while for larger nanoparticles conductivity becomes predominately ionic. Simulations revealed that the temperature dependence of Li ion conductivity in anatase is very weak, while in rutile the conductivity decreases with temperature in small nanoparticles and increases in large nanoparticles.