Atomistic simulation of Na2Ti3O7: Defects, dopants, and diffusion properties

Abstract

Na2Ti3O7 exhibits promise as a safe battery material for Na-ion batteries, currently undergoing extensive research. The atomistic simulation method is employed to scrutinize defects, dopant energies, and Na-ion migration in Na2Ti3O7. Notably, the Na-Frankel energy is the lowest, and the Na-anti-site cluster energy is lower than the Na-anti-site isolated energy. The migration of Na ions is observed to predominantly occur along the ab plane, where the activation energy is measured at 0.23 eV. K and Ge ions are identified as the most suitable isovalent and tetravalent dopants for Na and Ti sites, respectively. Furthermore, the introduction of the aliovalent dopant Al3+ ion on the Ti site can form additional Na+ ions. The electronic structures of the most favorable doped configurations are discussed.