title: Solvent Polarity Governs Ion Interactions and Transport in a Solvated Room-Temperature Ionic Liquid.
abstract: We explore the influence of the solvent dipole moment on cation-anion interactions and transport in 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl), [BMIM+][Tf2N-]. Free energy profiles derived from atomistic molecular dynamics (MD) simulations show a correlation of the cation-anion separation and the equilibrium depth of the potential of mean force with the dipole moment of the solvent. Correlations of the ion diffusivity with the dipole moment and the concentration of the solvent were further demonstrated by classical MD simulations. Quasi-elastic neutron scattering experiments with deuterated solvents reveal a complex picture of nanophase separation into the ionic liquid-rich and solvent-rich phases. The experiment corroborates the trend of concentration- and dipole moment-dependent enhancement of ion mobility by the solvent, as suggested by the simulations. Despite the considerable structural complexity of ionic liquid-solvent mixtures, we can rationalize and generalize the trends governing ionic transport in these complex electrolytes.
authors.affiliation: Chemical and Engineering Materials Division, Oak Ridge National Laboratory , PO Box 2008 MS6455, Oak Ridge, Tennessee 37831, United States.
authors.forename: Naresh C
authors.identifier: http://orcid.org/0000-0002-0213-2299
authors.initials: NC
authors.lastname: Osti
authors.affiliation: Department of Materials Science and Engineering, and A. J. Drexel Nanomaterials Institute, Drexel University , 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States.
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Van Aken
authors.affiliation: Department of Chemical and Biomolecular Engineering, Vanderbilt University , 2201 West End Avenue, Nashville, Tennessee 37235, United States.
authors.forename: Matthew W
authors.identifier: http://orcid.org/0000-0002-1460-3983
authors.initials: MW
authors.lastname: Thompson
authors.affiliation: Department of Chemical and Biomolecular Engineering, Vanderbilt University , 2201 West End Avenue, Nashville, Tennessee 37235, United States.
authors.forename: Felix
authors.initials: F
authors.lastname: Tiet
authors.affiliation: Department of Chemistry, University of California , 900 University Avenue, Riverside, California 92521, United States.
authors.forename: De-En
authors.identifier: http://orcid.org/0000-0001-5167-0731
authors.initials: DE
authors.lastname: Jiang
authors.affiliation: Department of Chemical and Biomolecular Engineering, Vanderbilt University , 2201 West End Avenue, Nashville, Tennessee 37235, United States.
authors.forename: Peter T
authors.initials: PT
authors.lastname: Cummings
authors.affiliation: Department of Materials Science and Engineering, and A. J. Drexel Nanomaterials Institute, Drexel University , 3141 Chestnut Street, Philadelphia, Pennsylvania 19104, United States.
authors.forename: Yury
authors.identifier: http://orcid.org/0000-0001-9423-4032
authors.initials: Y
authors.lastname: Gogotsi
authors.affiliation: Chemical and Engineering Materials Division, Oak Ridge National Laboratory , PO Box 2008 MS6455, Oak Ridge, Tennessee 37831, United States.
authors.forename: Eugene
authors.initials: E
authors.lastname: Mamontov