| 1. |
- Jonsson, Erlendur, 1983
(författare)
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Ionic liquids as electrolytes for energy storage applications – A modelling perspective
- 2020
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Ingår i: Energy Storage Materials. - : Elsevier BV. - 2405-8297. ; 25, s. 827-835
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Forskningsöversikt (refereegranskat)abstract
- Ionic liquids as electrolytes for energy storage devices is a promising field. Here, the various approaches of how ionic liquids can be modelled are discussed along with how the modelling connects to experimental results. Recent theoretical developments are highlighted along with extended discussion of what molecular dynamics simulation options are now available and what key results can be extracted. Ab initio work is also discussed, this includes some of the spectral properties, both of ionic liquids and their electrolyte formulations.
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| 2. |
- Monti, Damien, 1986, et al.
(författare)
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Towards standard electrolytes for sodium-ion batteries: physical properties, ion solvation and ion-pairing in alkyl carbonate solvents
- 2020
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 22:39, s. 22768-22777
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Tidskriftsartikel (refereegranskat)abstract
- The currently emerging sodium-ion battery technology is in need of an optimized standard organic solvent electrolyte based on solid and directly comparable data. With this aim we have made a systematic study of "simple"electrolyte systems consisting of two sodium salts (NaTFSI and NaPF6) dissolved in three different alkyl carbonate solvents (EC, PC, DMC) within a wide range of salt concentrations and investigated: (i) their more macroscopic physico-chemical properties such as ionic conductivity, viscosity, thermal stability, and (ii) the molecular level properties such as ion-pairing and solvation. From this all electrolytes were found to have useful thermal operational windows and electrochemical stability windows, allowing for large scale energy storage technologies focused on load levelling or (to a less extent) electric vehicles, and ionic conductivities on par with analogous lithium-ion battery electrolytes, giving promise to also be power performant. Furthermore, at the molecular level the NaPF6-based electrolytes are more dissociated than the NaTFSI-based ones because of the higher ionic association strength of TFSI compared to PF6- while two different conformers of DMC participate in the Na+ first solvation shells-a Na+ affected conformational equilibrium and induced polarity of DMC. The non-negligible presence of DMC in the Na+ first solvation shells increases as a function of salt concentration. Overall, these results should both have a general impact on the design of more performant Na-conducting electrolytes and provide useful insight on the very details of the importance of DMC conformers in any cation solvation studies.
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| 3. |
- Temprano, Israel, et al.
(författare)
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Toward Reversible and Moisture-Tolerant Aprotic Lithium-Air Batteries
- 2020
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Ingår i: Joule. - : Elsevier BV. - 2542-4351. ; 4:11, s. 2501-2520
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Tidskriftsartikel (refereegranskat)abstract
- The development of moisture-tolerant, LiOH-based non-aqueous Li-O2 batteries is a promising route to bypass the inherent limitations caused by the instability of their typical discharge products, LiO2 and Li2O2. The use of the I−/I3− redox couple to mediate the LiOH-based oxygen reduction and oxidation reactions has proven challenging due to the multiple reaction paths induced by the oxidation of I− on cell charging. In this work, we introduce an ionic liquid to a glyme-based electrolyte containing LiI and water and demonstrate a reversible LiOH-based Li-O2 battery cycling that operates via a 4 e−/O2 process with a low charging overpotential (below 3.5 V versus Li/Li+). The addition of the ionic liquid increases the oxidizing power of I3−, shifting the charging mechanism from IO−/IO3− formation to O2 evolution.
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| 4. |
- Zhao, Evan Wenbo, et al.
(författare)
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In situ NMR metrology reveals reaction mechanisms in redox flow batteries
- 2020
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 579:7798, s. 224-228
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale energy storage is becoming increasingly critical to balancing renewable energy production and consumption1. Organic redox flow batteries, made from inexpensive and sustainable redox-active materials, are promising storage technologies that are cheaper and less environmentally hazardous than vanadium-based batteries, but they have shorter lifetimes and lower energy density2,3. Thus, fundamental insight at the molecular level is required to improve performance4,5. Here we report two in situ nuclear magnetic resonance (NMR) methods of studying redox flow batteries, which are applied to two redox-active electrolytes: 2,6-dihydroxyanthraquinone (DHAQ) and 4,4′-((9,10-anthraquinone-2,6-diyl)dioxy) dibutyrate (DBEAQ). In the first method, we monitor the changes in the 1H NMR shift of the liquid electrolyte as it flows out of the electrochemical cell. In the second method, we observe the changes that occur simultaneously in the positive and negative electrodes in the full electrochemical cell. Using the bulk magnetization changes (observed via the 1H NMR shift of the water resonance) and the line broadening of the 1H shifts of the quinone resonances as a function of the state of charge, we measure the potential differences of the two single-electron couples, identify and quantify the rate of electron transfer between the reduced and oxidized species, and determine the extent of electron delocalization of the unpaired spins over the radical anions. These NMR techniques enable electrolyte decomposition and battery self-discharge to be explored in real time, and show that DHAQ is decomposed electrochemically via a reaction that can be minimized by limiting the voltage used on charging. We foresee applications of these NMR methods in understanding a wide range of redox processes in flow and other electrochemical systems.
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