Modeling of the Electronic Properties of M-Doped Supercells Li4Ti5O12–M (М = Zr, Nb) with a Monoclinic Structure for Lithium-Ion Batteries.

The T–x phase diagram of the quasi-binary system was refined and the isothermal cross section of the ternary system at 298 K was constructed. The equilibrium phase regions of 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 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 () compound with a monoclinic structure (m) was carried out. It has been shown that partial substitution of cations and oxygen in the structure increases the efficiency of a lithium-ion battery () both by stabilizing the structure and by increasing the diffusion rate of . Due to the contribution of d-orbitals ( 4d orbitals) to the exchange energy, partial polarization of electronic states occurs and the electronic conductivity of increases. The formation of oxygen vacancies in the crystal lattice, as in binary oxides, can create donor levels and improve the transport of and electrons. M-doping of the structure by replacing cations, in particular lithium, with Zr or Nb atoms noticeably reduces the band gap () of supercells. In this case, in the band structure, the Fermi level shifts to the conduction band and the band gap narrows. Decreasing the value increases the electronic and lithium-ion conductivity of supercells. [ABSTRACT FROM AUTHOR]