Difference in the electron energy loss spectra between the spinel-type Na3LiTi5O12 and Li4Ti5O12 clarified by density functional theory calculations

Li4Ti5O12 is an anode material for Li-ion batteries, and Na3LiTi5O12 is a candidate anode material for Na-ion batteries. Both materials have a spinel framework of Ti-O bonds; hence, the electronic structures are similar. However, the difference between Li4Ti5O12 and Na3LiTi5O12 is detected via electron energy loss spectra (EELS). Density functional theory calculations of the highest energy regions of the titanates show that the difference is caused by the orbital overlaps between the Rydberg orbitals of the O atoms in the 32e sites and alkali metal atoms in the 8a sites. When the 8a sites are occupied by Li, the interaction becomes large, and the peaks in the density of states and EELS become sharp. In contrast, when the 8a sites are occupied by Na, the interaction becomes small, and the peaks in the density of states and EELS become broad. These results imply that the cations in the 8a sites can interact with the Ti-O spinel framework and affect the resulting properties.

Automated summary

Li4Ti5O12 is an anode material for Li-ion batteries, and Na3LiTi5O12 is a candidate anode material for Na-ion batteries. The difference between these two materials is detected through electron energy loss spectra (EELS). Density functional theory calculations show that the interaction between the cations in the 8a sites and the Ti-O spinel framework affects the properties of the titanates.