Theoretical calculation of size- dependent properties and the impact of carbon doping on lithium titanate oxide nanoparticles as anode material in Li-ion batteries

Abstract

The technological improvement of lithium-ion battery (LIB) has been the center of research attention in the field of rechargeable batteries. This work reports investigation on prospects of lithium titanate oxide (LTO) nanoparticles as anode material in LIB via density functional theory and ab-initio molecular dynamics (AIMD) stimulations. The first study on effects of size variation and doping of carbon via AIMD simulations in LTO nanoparticles is studied here to explore the anodic properties of the material on the basis of structural properties, electronic characteristics, thermal stability, storage capacity, lithiation energy, and diffusion kinetics. The doping appeared to increase the storage capacity of LTO from 175 mAhg−1 to 1057 mAhg−1 which points to practicality of the material as anode in LIBs. The open circuit voltage is found as 3.08 V, 3.40 V, 2.70 V and 0.70 V for 1.2 nm, 1.5 nm, 3.4 nm and carbon doped nanoparticles respectively. Cl-NEB simulations are carried out to study the migration paths of Li and vacancy in the host structure indicated low energy barrier of 0.86 eV for 1.2 nm, 0.75 eV for 1.5 nm and 0.45 eV for the doped structure, respectively. Furthermore, the MD simulations indicate the diffusion coefficient as 4.3x10−12 m2/s, 5.0x10−12 m2/s, 0.83x10−12 m2/s and 1.72 x10−8 m2/s for 1.2 nm, 1.5 nm, 3.4 nm and doped 3.4 nm respectively. The calculated values of ionic conductivity of LIBs are 5.32 x 10−3 Sm−1, 0.19 x 10−2 Sm−1, 9.32 x 10−2 Sm−1 and 7.33 x 10−3 Sm−1 for 1.2 nm, 1.4 nm, 3.4 nm and doped 3.4 nm respectively.

Keywords Lithium titanate oxide (LTO), Density functional theory (DFT), Lithium-ion batteries (LIBs), Ab-initio molecular dynamics (AIMD), Anode