Effect of transition metal (M = Co, Ni, Cu) substitution on electronic structure and vacancy formation of Li3N
Boey, Freddy Yin Chiang
Date of Issue2011
School of Materials Science and Engineering
We carried out first principles calculations to investigate the effect of transition metal (M = Co, Ni, Cu) substitution on electronic structure and vacancy formation of Li3N in this study. Transition metals are shown to selectively substitute interplanar Li(1) atoms. Both Co and Ni substitution remarkably reduces the energy band gap to 0.55 eV in comparison with 1.13 eV of Li3N, while Cu substitution insignificantly decreases the energy band gap by 0.07 eV. Covalent bonding between transition metal atom and the coordinated N, which is manifested both visually by the contour plots of valence charge density difference and numerically by bond length variation, results in the formation of Li3−x−yMxyN with y dependent on the covalency and concentration of transition metal. Ni substitution significantly reduces VLi(2) formation energy, which suggests greatly increased Li vacancy concentration for improved Li ionic mobility and conduction. Therefore, controlling the energy band gap and vacancy concentration by transition metal substitution provides a viable approach to tailor Li3N for variable applications in rechargeable lithium ion batteries.
Journal of materials chemistry
© 2011 The Royal Society of Chemistry. This is the author created version of a work that has been peer reviewed and accepted for publication by Journal of Materials Chemistry, The Royal Society of Chemistry. It incorporates referee’s comments but changes resulting from the publishing process, such as copyediting, structural formatting, may not be reflected in this document. The published version is available at: [http://dx.doi.org/10.1039/c0jm01883j ].