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Eliasen KL, Gabriel J, Blochowicz T, Gainaru CP, Christensen TE, Niss K. What is the origin of slow relaxation modes in highly viscous ionic liquids? J Chem Phys 2024; 161:034506. [PMID: 39012811 DOI: 10.1063/5.0215661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Accepted: 06/27/2024] [Indexed: 07/18/2024] Open
Abstract
Room temperature ionic liquids (RTILs) are molten salts consisting entirely of ions and have over the past decades gained increased interest due to their high potential in applications. These structurally complex systems often display multiple relaxation modes in the response functions at lower frequencies, hinting to complex underlying mechanisms. While the existence of these multimodal spectra in the shear mechanical, dielectric, and light scattering response of RTILs has been confirmed multiple times, controversy still surrounds the origin. This paper, therefore, aims to provide additional insights into the multimodal spectra seen in RTILs by presenting new shear mechanical results on seven different RTILs: Pyr1n-TFSI with n = 4, 6, and 8; Pyr18-TFSI mixed with Li-TFSI in two high concentrations; and Cn-mim-BF4 with n = 3 and 8. Dynamic depolarized light scattering was also measured on one of the Pyr18-TFSI Li-salt mixtures. These specific cases were analyzed in detail and put into a bigger perspective together with an overview of the literature. Recent literature offers two specific explanations for the origin of the multimodal shear mechanical spectra: (1) cation-anion time scale separation or (2) combined cation-anion relaxation in addition to a dynamic signal from mesoscale aggregates at lower frequencies. However, neither of these two pictures can consistently explain all the results on different ionic liquids. Instead, we conclude that the origin of the multimodal spectrum is system specific. This underlines the complexity of this class of liquids and shows that great care must be taken when making general conclusions based on specific cases.
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Affiliation(s)
- Kira L Eliasen
- "Glass and Time," IMFUFA, Department of Science and Environment, Roskilde University, Roskilde 4000, Denmark
| | - Jan Gabriel
- "Glass and Time," IMFUFA, Department of Science and Environment, Roskilde University, Roskilde 4000, Denmark
| | - Thomas Blochowicz
- Institut für Festkörperphysik, Technische Universität Darmstadt, Darmstadt 64289, Germany
| | - Catalin P Gainaru
- Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Tage E Christensen
- "Glass and Time," IMFUFA, Department of Science and Environment, Roskilde University, Roskilde 4000, Denmark
| | - Kristine Niss
- "Glass and Time," IMFUFA, Department of Science and Environment, Roskilde University, Roskilde 4000, Denmark
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Stachurski CD, Davis JH, Cosby T, Crowley ME, Larm NE, Ballentine MG, O’Brien RA, Zeller M, Salter EA, Wierzbicki A, Trulove PC, Durkin DP. Physical and Electrochemical Analysis of N-Alkylpyrrolidinium-Substituted Boronium Ionic Liquids. Inorg Chem 2023; 62:18280-18289. [PMID: 37870915 PMCID: PMC10630938 DOI: 10.1021/acs.inorgchem.3c02971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Indexed: 10/24/2023]
Abstract
In this work, a series of novel boronium-bis(trifluoromethylsulfonyl)imide [TFSI-] ionic liquids (IL) are introduced and investigated. The boronium cations were designed with specific structural motifs that delivered improved electrochemical and physical properties, as evaluated through cyclic voltammetry, broadband dielectric spectroscopy, densitometry, thermogravimetric analysis, and differential scanning calorimetry. Boronium cations, which were appended with N-alkylpyrrolidinium substituents, exhibited superior physicochemical properties, including high conductivity, low viscosity, and electrochemical windows surpassing 6 V. Remarkably, the boronium ionic liquid functionalized with both an ethyl-substituted pyrrolidinium and trimethylamine, [(1-e-pyrr)N111BH2][TFSI], exhibited a 6.3 V window, surpassing previously published boronium-, pyrrolidinium-, and imidazolium-based IL electrolytes. Favorable physical properties and straightforward tunability make boronium ionic liquids promising candidates to replace conventional organic electrolytes for electrochemical applications requiring high voltages.
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Affiliation(s)
| | - James H. Davis
- Department
of Chemistry, University of South Alabama, Mobile, Alabama36688, United States
| | - Tyler Cosby
- School
of Mathematics and Sciences, University
of Tennessee Southern, Pulaski, Tennessee38478, United States
| | - Margaret E. Crowley
- Department
of Chemistry, University of South Alabama, Mobile, Alabama36688, United States
| | - Nathaniel E. Larm
- Department
of Chemistry, U.S. Naval Academy, Annapolis, Maryland21402, United States
| | - Mollie G. Ballentine
- Department
of Chemistry, University of South Alabama, Mobile, Alabama36688, United States
| | - Richard A. O’Brien
- Department
of Chemistry, University of South Alabama, Mobile, Alabama36688, United States
| | - Matthias Zeller
- Department
of Chemistry, Purdue University, West Lafayette, Indiana47907, United States
| | - E. Alan Salter
- Department
of Chemistry, University of South Alabama, Mobile, Alabama36688, United States
| | - Andrzej Wierzbicki
- Department
of Chemistry, University of South Alabama, Mobile, Alabama36688, United States
| | - Paul C. Trulove
- Department
of Chemistry, U.S. Naval Academy, Annapolis, Maryland21402, United States
| | - David P. Durkin
- Department
of Chemistry, U.S. Naval Academy, Annapolis, Maryland21402, United States
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Pabst F, Kraus J, Reynolds M, Mattsson J, Blochowicz T. Preserving fast ion dynamics while introducing mechanical rigidity in gelatin-based ionogels. SOFT MATTER 2023; 19:1418-1428. [PMID: 36723269 DOI: 10.1039/d2sm01143c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Ionogels are gels containing ions, often an ionic liquid (IL), and a gelling agent. They are promising candidates for applications including batteries, photovoltaics or fuel cells due to their chemical stability and high ionic conductivity. In this work we report on a thermo-irreversible ionic gel prepared from a mixture of the ionic liquid 1-butyl-3-methylimidazolium ([BMIM]) dicyanamide ([DCA]), water and gelatin, which combines the advantages of an ionic liquid with the low cost of gelatin. We use (i) dielectric spectroscopy to monitor the ion transport, (ii) dynamic light scattering techniques to access the reorientational motions of the ions, as well as fluctuations of the gel matrix, and (iii) rheology to determine the shear response from above room temperature down to the glass transition. In this way, we are able to connect the microscopic ion dynamics with the meso- and macroscopic behavior of the gelatin matrix. We show, by comparing our results to those for a IL-water mixture from a previous study, that although some weak additional slow relaxation modes are present in the gel, the overall ion dynamics is hardly changed by the presence of gelatin. The macroscopic mechanical response, as probed by rheology, is however dominated by the gel matrix. This behaviour can be highly useful e.g. in battery gel electrolytes which prevent electrolyte leakage and combine mechanical rigidity and flexibility.
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Affiliation(s)
- Florian Pabst
- TU Darmstadt, Institute for Condensed Matter Physics, 64289 Darmstadt, Germany.
| | - Jennifer Kraus
- TU Darmstadt, Institute for Condensed Matter Physics, 64289 Darmstadt, Germany.
| | - Matthew Reynolds
- School of Physics and Astronomy, University of Leeds, LS2 9JT Leeds, UK
| | - Johan Mattsson
- School of Physics and Astronomy, University of Leeds, LS2 9JT Leeds, UK
| | - Thomas Blochowicz
- TU Darmstadt, Institute for Condensed Matter Physics, 64289 Darmstadt, Germany.
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Qi G, Dong Y, Feng Y, Wei J, Han P, Bai X, He B. The effect of thermodynamic changes in the cooling of saline soils on the corrosion system of carbon steels. RSC Adv 2022; 12:28767-28779. [PMID: 36320490 PMCID: PMC9549485 DOI: 10.1039/d2ra04889b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 10/04/2022] [Indexed: 11/07/2022] Open
Abstract
In this experiment, Q235 and X80 carbon steels, which are widely used in oil and gas pipelines and ancillary facilities, were selected to study the changes in the corrosion behaviour and mechanism of carbon steels in the process of natural saline soil cooling to a freezing state through electrochemical testing. The equivalent circuit model of carbon steel before and after the freezing phase transformation in the soil was determined. Based on the corrosion kinetic parameters and soil thermodynamic changes, the influencing factors of steel corrosion during the cooling process were systematically analysed. It was found that temperature mainly affected carbon steel corrosion by changing the properties of the solution. The main factors affecting the corrosion behaviour of the carbon steel were the thermal motion of molecules, ions, and electrons in solution, oxygen dissolution and diffusion, ion adsorption, diffusion mass transfer, and unfrozen water content change during the cooling process. The corrosion behavior and mechanism of carbon steels during cooling to a freezing state in natural saline soil were studied by an electrochemical test.![]()
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Affiliation(s)
- Gang Qi
- College of Civil Engineering, Taiyuan University of TechnologyTaiyuan 030024P. R. China
| | - Yanli Dong
- Civil Engineering School of Environment and Safety Engineering, North University of ChinaNo. 3 Xueyuan RoadTaiyuan 030051ShanxiP. R. China
| | - Yongxiang Feng
- College of Civil Engineering, Taiyuan University of TechnologyTaiyuan 030024P. R. China
| | - Jianjian Wei
- College of Civil Engineering, Taiyuan University of TechnologyTaiyuan 030024P. R. China
| | - Pengju Han
- College of Civil Engineering, Taiyuan University of TechnologyTaiyuan 030024P. R. China
| | - Xiaohong Bai
- College of Civil Engineering, Taiyuan University of TechnologyTaiyuan 030024P. R. China
| | - Bin He
- College of Civil Engineering, Taiyuan University of TechnologyTaiyuan 030024P. R. China
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Dielectric Study of Tetraalkylammonium and Tetraalkylphosphonium Levulinate Ionic Liquids. Int J Mol Sci 2022; 23:ijms23105642. [PMID: 35628452 PMCID: PMC9145921 DOI: 10.3390/ijms23105642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/09/2022] [Accepted: 05/14/2022] [Indexed: 11/17/2022] Open
Abstract
Broadband dielectric spectroscopy in a broad temperature range was employed to study ionic conductivity and dynamics in tetraalkylammonium- and tetraalkylphosphonium-based ionic liquids (ILs) having levulinate as a common anion. Combining data for ionic conductivity with data obtained for viscosity in a Walden plot, we show that ionic conductivity is controlled by viscosity while a strong association of ions takes place. Higher values for ionic conductivities in a broad temperature range were found for the tetraalkylphosphonium-based IL compared to its ammonium homolog in accordance with its lower viscosity. Levulinate used in the present study as anion was found to interact and associate stronger with the cations forming ion-pairs or other complexes compared to the NTf2 anion studied in literature. In order to analyze dielectric data, different fitting approaches were employed. The original random barrier model cannot well describe the conductivity especially at the higher frequencies region. In electric modulus representation, two overlapping mechanisms contribute to the broad low frequencies peak. The slower process is related to the conduction mechanism and the faster to the main polarization process of the complex dielectric permittivity representation. The correlation of the characteristic time scales of the previous relaxation processes was discussed in terms of ionic interactions.
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Pabst F, Kraus J, Kloth S, Steinrücken E, Kruteva M, Radulescu A, Vogel M, Blochowicz T. Evidence of supercoolable nanoscale water clusters in an amorphous ionic liquid matrix. J Chem Phys 2021; 155:174501. [PMID: 34742203 DOI: 10.1063/5.0066180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Nanoscale water clusters in an ionic liquid matrix, also called "water pockets," were previously found in some mixtures of water with ionic liquids containing hydrophilic anions. However, in these systems, at least partial crystallization occurs upon supercooling. In this work, we show for mixtures of 1-butyl-3-methylimidazolium dicyanamide with water that none of the components crystallizes up to a water content of 72 mol. %. The dynamics of the ionic liquid matrix is monitored from above room temperature down to the glass transition by combining depolarized dynamic light scattering with broadband dielectric and nuclear magnetic resonance spectroscopy, revealing that the matrix behaves like a common glass former and stays amorphous in the whole temperature range. Moreover, we demonstrate by a combination of Raman spectroscopy, small angle neutron scattering, and molecular dynamics simulation that, indeed, nanoscale water clusters exist in this mixture.
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Affiliation(s)
- Florian Pabst
- TU Darmstadt, Institute for Condensed Matter Physics, 64289 Darmstadt, Germany
| | - Jennifer Kraus
- TU Darmstadt, Institute for Condensed Matter Physics, 64289 Darmstadt, Germany
| | - Sebastian Kloth
- TU Darmstadt, Institute for Condensed Matter Physics, 64289 Darmstadt, Germany
| | - Elisa Steinrücken
- TU Darmstadt, Institute for Condensed Matter Physics, 64289 Darmstadt, Germany
| | - Margarita Kruteva
- Jülich Centre for Neutron Science JCNS (JCNS-1), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Aurel Radulescu
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, 85747 Garching, Germany
| | - Michael Vogel
- TU Darmstadt, Institute for Condensed Matter Physics, 64289 Darmstadt, Germany
| | - Thomas Blochowicz
- TU Darmstadt, Institute for Condensed Matter Physics, 64289 Darmstadt, Germany
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