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Generation and Control of Electrohydrodynamic Flows in Aqueous Electrolyte Solutions
Published on: September 7, 2018
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Non-Newtonian Dynamics in Water-in-Salt Electrolytes
Tsuyoshi Yamaguchi1, Andrei Dukhin2, Young-Jay Ryu3
1Graduate School of Engineering, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8603, Japan.
The Journal of Physical Chemistry Letters
|December 22, 2023
Summary
Water-in-salt electrolytes offer advantages for lithium-ion batteries. This study reveals their viscosities are governed by TFSI- network relaxation, impacting battery performance.
Area of Science:
- Electrochemistry
- Materials Science
- Physical Chemistry
Background:
- Water-in-salt electrolytes are promising for advanced lithium-ion batteries, offering benefits over traditional non-aqueous systems.
- A 3V operating window was previously demonstrated using a LiTFSI-water electrolyte with a solid-electrolyte interface.
- Electrolyte viscosity is critical, as high viscosity typically correlates with low ionic conductivity.
Purpose of the Study:
- To investigate the shear and longitudinal viscosities of LiTFSI-water electrolytes.
- To understand the relationship between viscosity, frequency, and concentration in these electrolytes.
- To elucidate the underlying mechanisms governing the rheological properties of water-in-salt electrolytes.
Main Methods:
- Measurements of shear stress and compressional longitudinal stress.
- Analysis of viscosity as a function of frequency and concentration.
- Comparison with quasielastic neutron scattering data.
Main Results:
- Both shear and longitudinal viscosities were found to be frequency-dependent.
- Identical frequency and concentration dependencies were observed in the high-concentration region.
- Viscosity behavior is linked to the structural relaxation of the TFSI- network.
Conclusions:
- LiTFSI-water electrolytes exhibit unusual non-Newtonian fluid behavior.
- A single relaxation mechanism governs both shear and longitudinal viscosities.
- Understanding these rheological properties is key for optimizing advanced battery electrolytes.
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