Li-diffusion pathways in Zr2CO2 and Zr2CS2 MXenes using the Bond Valence Sum model

Two-dimensional materials such as MXenes are being actively considered by the community for energy storage applications. Here, we employ Density Functional Theory (DFT) to model O and S terminated Zr2C MXenes. We find that the most energetically favourable positions for the termination atoms to sit...

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Bibliographic Details
Published in:Computational materials science 2022-01, Vol.201, Article 110868
Main Authors: Papadopoulou, Konstantina A., Chroneos, Alexander, Christopoulos, Stavros-Richard G.
Format: Article
Language:English
Subjects:
Bond Valence Sum
Conductive pathways
Energy barrier
Li diffusion
MXenes
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Summary:Two-dimensional materials such as MXenes are being actively considered by the community for energy storage applications. Here, we employ Density Functional Theory (DFT) to model O and S terminated Zr2C MXenes. We find that the most energetically favourable positions for the termination atoms to sit are on top of the second-layer Zr atoms, in agreement with previous studies. Finally, arbitrarily placing a Li-ion on the surface of the MXenes, we apply the Bond Valence Sum (BVS) model to calculate Bond Valence Site Energies (BVSE). We show that BVS is a good substitute for DFT particularly for diffusion pathways, as it yields much faster results and with good accuracy, with the added advantage of not needing exact positions for the atoms. BVS can, therefore, be used as a quick filter when searching for low migration barriers in MXenes and two-dimensional materials. •BVS is a good substitute for DFT for finding Li ion’s diffusion pathways.•BVS does not need exact positions for the atoms.•BVS can be used as a quick filter when searching for low migration barriers in MXenes.
ISSN:0927-0256
1879-0801
DOI:10.1016/j.commatsci.2021.110868