Speaker
Description
Surface cationic doping has been deemed one of the most effective methods of reducing the number of trivalent manganese (Mn3+) ions that undergo a disproportionation reaction in lithium manganese oxide-based (LiMn2O4) lithium-ion batteries. However, the effect of surface doping on the major LiMn2O4 surfaces and their interactions with the electrolyte components is not yet fully understood. In this work, we present the effect of surface Nb doping and the adsorption of electrolyte components (ethylene carbonate and hydrofluoric acid) on the major LiMn2O4 (001),(011), and (111) surfaces using the spin-polarized density functional theory-based calculations [DFT+U-D3 (BJ)]. During Nb 5+ substitution on the top (Nbt) and sub-surface layers (Nbs), it was found that the stability of the (111) surface plane greatly improves for Nbs, causing it to dominate the morphology. This is an interesting, since it has previously been suggested that exposing the (111) surface promotes the formation of a stable solid electrolyte interphase (SEI), which could significantly reduce Mn dissolution. Moreover, both EC and HF greatly preferred binding with the surfaces through the Nb instead of Mn atoms, and the largest adsorption energy was calculated for EC on Nbb (Nb-doped on both Nbt and Nbs) of (001) and HF on Nbt (111) surfaces. Furthermore, the EC/HF adsorptions further enhance the stability of the Nbs (111) surface plane. However, minimal charge transfer was calculated for both HF and EC interacting with the pure and Nb-doped surfaces.
Keywords: Doping, adsorption, Density functional theory, Li-ion batteries, Surface chemistry
Level for award;(Hons, MSc, PhD, N/A)?
PhD.
| Apply to be considered for a student ; award (Yes / No)? | Yes |
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