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- Lundin, Filippa, 1992, et al.
(författare)
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Ion Dynamics and Nanostructures of Diluted Ionic Liquid Electrolytes
- 2022
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 126:38, s. 16262-16271
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Tidskriftsartikel (refereegranskat)abstract
- Diluted ionic liquid electrolytes are promising candidates in next-generation batteries enabling the implementation of lithium metal anodes. The diluent should fully mix with the ionic liquid while not interacting with the Li ions to preserve the ionic liquid character, which is beneficial for Li-metal electrode stability. We report on the influence of a hydrofluoroether (HFE) diluent on ion dynamics and nanostructure of an ionic liquid electrolyte. We show that the ionic liquid and the diluent are fully miscible and that the solvation structure of the Li ions is not affected by the presence of HFE. The increase in the conductivity by the addition of the diluent is directly related to a decrease in viscosity with faster dynamics of all ionic species. However, the relative increase in mobility is considerably larger for the ionic liquid cation as a result of a preferred interaction with HFE. On the microscopic scale, more complex local non-Gaussian diffusive dynamics are found, faster than what is expected from the self-diffusion coefficient. The relative change of the dynamics with the addition of HFE on macro- and microscopic length scales correlates well, which underlines the connection between the motions probed on different length and time scales.
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| 2. |
- Lundin, Filippa, 1992
(författare)
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Local Structure and Dynamics of Next Generation Electrolytes - linking microscopic and macroscopic properties
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The electrolyte is a crucial part of a battery in terms of performance, longevity and safety. However, the state-of-the-art electrolytes for lithium-ion batteries are based on organic solvents and Li-salts (typically at 1M concentration) which are volatile and degrade at higher temperatures. In addition, these electrolytes are not suitable for next generation battery concepts where the use of metallic lithium at the anode side is a prerequisite. Thus, there is currently a strong effort to find new electrolyte concepts to both improve safety of current battery technology and pave way for next generation batteries. In the search for new electrolytes, highly concentrated electrolytes and ionic liquids have been proposed as alternatives through properties such as high thermal stability, lower reactivity with cell components and increased electrochemical stability window. A common feature for highly concentrated electrolytes and ionic liquids is an ordering on mesoscopic length scales, normally not found in simple liquids, resulting from the correlation between the ions. This nanostructure can be expected to influence the ion transport and a key to developing these new electrolyte concepts is to understand the structure and dynamics on mesoscopic length scales and how this links to macroscopic transport. In this thesis, the microscopic properties of ionic liquids and diluted ionic liquids are investigated together with highly concentrated electrolytes based on an organic solvent. To achieve this goal X-ray and neutron scattering are invaluable tools as they allow for measurements at the time and length scale of typical molecular motions and interactions. Complementary techniques such as conductivity and viscosity measurements, differential scanning calorimetry, and Raman spectroscopy have been used in order to link between the macroscopic and microscopic properties and between local structure and dynamics.
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