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Accelerated lithium-ion diffusion a ligand 'hopping' mechanism in lithium enriched solvate ionic liquids
Solvate ionic liquids (SILs), equimolar amounts of lithium salts and polyether glymes, are well studied highly customisable "designer solvents". Herein the physical, thermal and ion mobility properties of SILs with increased LiTFSI (LiTFSA) concentration, with ligand 1 : >1 LiTFSI stoic...
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Published in: | Physical chemistry chemical physics : PCCP 2023-11, Vol.25 (43), p.29614-29623 |
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Main Authors: | , , , , |
Format: | Article |
Language: | |
Online Access: | Get full text |
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Summary: | Solvate ionic liquids (SILs), equimolar amounts of lithium salts and polyether glymes, are well studied highly customisable "designer solvents". Herein the physical, thermal and ion mobility properties of SILs with increased LiTFSI (LiTFSA) concentration, with ligand 1 : >1 LiTFSI stoichiometric ratios, are presented. It was found that between 60-80 °C, the lithium cation diffuses up to 4 times faster than the corresponding anion or ligand (glyme). These systems varied from viscous liquids to self-supporting gels, though were found to thin exponentially when heated to mild temperatures (50-60 °C). They were also found to be thermally stable, up to 200 °C, well in excess of normal operating temperatures. Ion mobility, assessed under an electric potential
via
ionic conductivity, showed the benefit of SIL optimisation for attaining greater concentrations of Li
+
cations to store charge during supercapacitor charging and discharging. Molecular dynamics simulations interrogate the mechanism of enhanced diffusion at high temperatures, revealing a lithium hopping mechanism that implicates the glyme in bridging two lithiums through changes in the denticity.
Herein the properties of SILs with increased LiTFSI (LiTFSA) concentration, with ligand 1 : >1 LiTFSI stoichiometric ratios, are presented. |
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ISSN: | 1463-9076 1463-9084 |
DOI: | 10.1039/d3cp04666d |