Stability and investigation of LiTiO2 cathode materials for lithium-ion batteries and optoelectronic devices: An ab initio calculations

Abstract

In this study, the structural stability and electronic, thermodynamic, and optical properties of Lithium titanium oxide (LiTiO₂) were studied by first-principles calculations based on density functional theory (DFT). The calculated lattice constant for LiTiO₂ is 8.45 Å. The volume change of titanium dioxide (TiO₂) equals 6.15% during lithium insertion/extraction. The relevant characteristics of the battery are 1.99 V vs. Li⁺/Li for the voltage and 285 Wh.kg⁻¹ for the energy density. The thermodynamic properties of LiTiO₂ are obtained by the semi-harmonic Debye model. The heat capacity of LiTiO₂ is 370 J.mol⁻¹.K⁻¹ approximately. The value of the heat capacity is high at constant volume. Therefore, the LiTiO₂ can be used as a heat storage material. The Debye stiffness of LiTiO₂ increases as the pressure increases. As a result, LiTiO₂ has various properties that make it suitable to be used as a cathode material in Li-ion batteries. Some optical properties of LiTiO₂ compound have been measured. The dielectric constant ε₁(0) for LiTiO₂ compound is 47 if we use the GGA-PBE approach and 74.12 if we use the DFT + U approach. In addition, the LiTiO₂ compound shows excellent absorption capacity in the ultraviolet region. So, the LiTiO₂ can be used in optical memory devices. The high reflectivity in the visible region opens the possibility of using LiTiO₂ as a coating material to reduce solar heating.