Affiliation:
1. Nagiyev Institute of Catalysis and Inorganic Chemistry, Ministry of Science and Education of Azerbaijan
2. Scientific Research Institute of Geotechnological Problems of Oil, Gas and Chemistry
3. Institute of Physics, Ministry of Science and Education of Azerbaijan
4. Khazar University
5. Valiev Physics and Technology Institute, Russian Academy of Sciences
Abstract
The T–x phase diagram of the quasi-binary system Li2O–TiO2 was refined and the isothermal cross section of the ternary Li–Ti–O system at 298 K was constructed. The equilibrium phase regions of Li–Ti–O in the solid state are determined with the participation of boundary binary oxides and four intermediate ternary compounds , , and . Using the density functional theory (DFT LSDA) method, the formation energies of the indicated ternary compounds of the Li2O–TiO2 system were calculated and the dependence of on the composition was plotted.
Ab initio modeling of supercells based on M-doped anode material based on the (LTO) compound with a monoclinic structure () was carried out. It has been shown that partial substitution of cations and oxygen in the m-LTO–M structure increases the efficiency of a lithium-ion battery (LIB) both by stabilizing the structure and by increasing the diffusion rate of . Due to the contribution of d-orbitals (Zr4+-4d, Nb3+-4d orbitals) to the exchange energy, partial polarization of electronic states occurs and the electronic conductivity of m-LTO–M increases. The formation of oxygen vacancies in the m-LTO–M crystal lattice, as in binary oxides, can create donor levels and improve the transport of and electrons.
M-doping of the m-LTO structure by replacing cations, in particular lithium, with Zr or Nb atoms noticeably reduces the band gap (Eg) of m-LTO–M supercells. In this case, in the m-LTO–M band structure, the Fermi level shifts to the conduction band and the band gap narrows. Decreasing the Eg value increases the electronic and lithium-ion conductivity of m-LTO–M supercells.
Publisher
The Russian Academy of Sciences