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Comparison of the Performances of Different Computational Methods to Calculate the Electrochemical Stability of Selected Ionic Liquids

Authors :
Sergio Brutti
Annalisa Paolone
Source :
Materials, Volume 14, Issue 12, Materials, Vol 14, Iss 3221, p 3221 (2021), Materials (Basel) 14 (2021): 3221-1–3221-12. doi:10.3390/ma14123221, info:cnr-pdr/source/autori:Paolone A.; Brutti S./titolo:Comparison of the performances of different computational methods to calculate the electrochemical stability of selected ionic liquids/doi:10.3390%2Fma14123221/rivista:Materials (Basel)/anno:2021/pagina_da:3221-1/pagina_a:3221-12/intervallo_pagine:3221-1–3221-12/volume:14
Publication Year :
2021
Publisher :
Multidisciplinary Digital Publishing Institute, 2021.

Abstract

The electrochemical stability windows (ESW) of selected ionic liquids have been calculated by comparing different computational approaches previously suggested in the literature. The molecular systems under study are based on di-alkyl imidazolium and tetra-alkyl ammonium cations coupled with two different imide anions (namely, bis-fluorosulfonyl imide and bis-trifluoromethyl sulfonyl imide), for which an experimental investigation of the ESW is available. Thermodynamic oxidation and reduction potentials have here been estimated by different models based on calculations either on single ions or on ionic couples. Various Density Functional Theory (DFT) functionals (MP2, B3LYP, B3LYP including a polarizable medium and empirical dispersion forces) were exploited. Both vertical and adiabatic transitions between the starting states and the oxidized or reduced states were considered. The approach based on calculations on ionic couples is not able to reproduce the experimental data, whatever the used DFT functional. The best quantitative agreement is obtained by calculations on single ions when the MP2 functional in vacuum is considered and the transitions between differently charged states are vertical (purely electronic without the relaxation of the structure). The B3LYP functional underestimates the ESW. The inclusion of a polar medium excessively widens the ESW, while a large shrinkage of the ESW is obtained by adopting an adiabatic transition scheme instead of a vertical transition one.

Details

Language :
English
ISSN :
19961944
Database :
OpenAIRE
Journal :
Materials
Accession number :
edsair.doi.dedup.....2430dd8ab42bab42a1e38af5c312e6b4
Full Text :
https://doi.org/10.3390/ma14123221