Electronic structure and vacancy formation of Li3N

The electronic structure and vacancy formation of Li3N were studied using first principles methods. We found Li3N exhibits strong ionic character with slight covalent bonding between N and Li. The Li vacancy formation energy decreases with an increase in nitrogen partial pressure, while the N vacancy formation energy increases with increasing nitrogen partial pressure. The Li(2) site vacancy is found to have the lowest formation energy under nitrogen-rich conditions. Formation of VLi(2)− brings about delocalization of valence electrons, and reduces the band gap by 0.2 eV. These results suggest potential ways to enhance vacancy concentration in Li3N for higher ionic conductivity.