Structural, Electronic, and Li Migration Properties of RE-Doped (RE = Ce, La) LiCoO₂for Li-ion Batteries: A First-Principles Investigation

Abstract

Rare earth elements, known for their large radius, high charge, and strong self-polarization ability, are expected to bring improvements in Li-ion batteries. However, some basic issues such as structural variation, the nature of the improved Li mobility, and electronic conductivity in rare earth-doped electrode compounds are still unrevealed. In the present work, the structural, electronic, and Li migration properties of Ce-and La-doped LiCoO 2 cathode materials are systematically studied by using the first-principles calculations. The results show that after rare earth elements are doped, the cell volume expands with local structure distortion around the substitution site. Meanwhile, the doped systems remain insulating characteristics with decreased band gap. The migration barriers vary considerably depending on different paths due to the competition between the increase of Li slab distance and the variation of potential energy surface caused by the doping of rare earth elements. The minimum activation barriers for Li motion decease significantly from 0.669 to 0.382 eV and to 0.239 eV upon Ce and La doping, respectively. Furthermore, Li ion migrations along the entire supercell are also studied.

Lanthanide doping induced electrochemical enhancement of Na2Ti3O7 anodes for sodium-ion batteries

“…3e and f and S7 (ESI † ). 26 It can be seen that NTO shows a direct bandgap of 3.07 eV while the bandgap of NTO:Yb decreased to 0.58 eV, which indicates that the polaron migration energy barrier along the constrained pathway is decreased, 25 thus attributing to a larger electronic conductivity of NTO:Yb.…”

“…It is believed that the crystal lattice distortion owing to the introduction of lanthanide ions will give rise to the generation of oxygen vacancies. 25 The reaction for oxygen vacancy formation using Kroger–Vink notation can be expressed as: …”

A review on first principles based studies for improvement of cathode material of lithium ion batteries

“…4 shows the spin polarized band structure, from which the impurity states at the edge of Fermi level can be seen. Band decomposed charge densities are also given [77] .…”

“…Band structure and band decomposed charge density of Ce doped LiCoO 2 and La doped LiCoO 2 (Published with the permission from ACS)[77] .…”

Effect of La3+ Modification on the Electrochemical Performance of Na3V2(PO4)2F3

“…However, in some cases, metal ions are able to replace one another in a limited range of compositions, although the difference in their radii exceeds 60% [10]. The influence of the Ce 4+ -and La 3+ -doping on the crystal and electronic structure of LiCoO 2 has been investigated by the first-principles calculations [11]. The results indicated that Ce 4+ and La 3+ -doped LiCoO 2 has expanded Li + slab distances, thus decreasing the Li + migration energy barrier; the diffusion coefficient was improved by 4 and 7 orders of magnitude, respectively.…”