Effect of Solvent Motion on Ion Transport in Electrolytes

Predicted species velocities when a 500 μm thick 2.58 M LiTFSI/PEO electrolyte is polarized at 0.3 mA/cm2 constant current density and 90oC in a Li-Li symmetric cell.

Scientific Achievement

Typically, the solvent is assumed to be immobile in a polarized electrolyte. However, recent JCESR measurements show non-zero solvent velocity. This article proposes a continuum theory to predict such solvent motion and its influence on other electrolyte fields.

Significance and Impact

Often electrolyte transport properties are obtained by assuming that the solvent is immobile. We show this is an inaccurate assumption and provide a consistent framework to account for solvent motions across different experiments for measuring electrolyte properties. This work is critical to accurately screen electrolytes for new batteries.

Research Details

  • LiTFSI/PEO electrolyte exhibits a negative cation transference number at 2.58 M salt concentration.
  • If the solvent dynamics is not accounted for, one would expect negative cation velocity at short times as shown in (c).
  • Instead, when accounted for the solvent dynamics ((a) and (b)), the cation velocity is always positive for this situation.
  • Electrophoretic NMR (eNMR) is a technique for measuring transference number based on cation velocity at short times. Comparing (a) and (c), one can justify the importance of solvent motion in analyzing eNMR measurements.

Download this highlight 

DOI: 10.1149/1945-7111/ac6329

Latest Updates

See All
  • JCESR Spotlight: Bob Jin Kwon, A Postdoc with Passion and Perseverance

    Argonne recognizes Kwon’s contributions to battery science with the Postdoctoral Performance Award. Article authored by: Michael Matz, Argonne Associate Bob Jin Kwon likes a good challenge, particularly when it comes to developing completely new kinds of batteries. “Developing new battery technologies is very challenging,” said … Read More

  • JCESR Spotlight: Lily Robertson Recognized for Her Contributions to Battery Research

    Argonne’s Postdoctoral Performance Award recognizes scientific achievements, leadership, and collaboration. Article authored by: Michael Matz, Argonne Associate Since her early days growing up in the Pacific Northwest, Lily Robertson has always wanted to help make the world a better place. “For as … Read More

  • Understanding fluorine-free electrolytes via small-angle X-ray scattering

    We compare the solvation phenomenon of sodium tetraphenylborate (NaBPh4) salt dissolved in organic solvents of propylene carbonate (PC), 1,2-dimethoxyethane (DME), acetonitrile (ACN) and tetrahydrofuran (THF) by SAXS/WAXS measurement and MD simulation. Read More

  • Navigating the Minefield of Battery Literature

    This is an invited perspective aiming to help researchers new to the field of battery research to circumvent certain recurring misconceptions and inaccuracies in the current battery literature. It covers the electrolyte ideality and practical situation in batteries, the difficulty in accurately determining ion transference … Read More

  • Quantifying Lithium Ion Exchange in Solid Electrolyte Interphase (SEI) on Graphite Anode Surfaces

    By using Li isotopic labelling of SEIs and electrolytes followed by time-of-flight secondary-ion mass spectroscopy and solid-state NMR analyses, we found that the majority of Li+ “immobilized” in the chemical ingredients were exchanged after 1 SEI formation cycle. Ion exchange by diffusion based on concentration … Read More