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Molecular dynamics simulations of highly concentrated salt solutions : structural and transport effects in polymer electrolytes

journal contribution
posted on 01.07.1992, 00:00 authored by Maria ForsythMaria Forsyth, V Payne, M Ratner, S de Leeuw, D Shriver
Structural, thermodynamic and transport properties have been calculated in concentrated non-aqueous NaI solutions using molecular dynamics simulations. Although the solvent has been represented by a simplistic Stockmayer fluid (spherical particles with point dipoles), the general trends observed are still a useful indication of the behavior of real non-aqueous electrolyte systems. Results indicate that in low dielectric media, significant ion pairing and clustering occurs. Contact ion pairs become more prominent at higher temperatures, independent of the dielectric strength of the solvent. Thermodynamic analysis shows that this temperature behavior is predominantly entropically driven. Calculation of ionic diffusivities and conductivities in the NaI/ether system confirms the clustered nature of the salt, with the conductivities significantly lower than those predicted from the Nernst-Einstein relation. In systems where the solvent-ion interactions increase relative to ion-ion interactions (lower charge or higher solvent dipole moment), less clustering is observed and the transport properties indicate independent motion of the ions, with higher calculated conductivities. The solvent in this system is the most mobile species, in comparison with the polymer electrolytes where the solvent is practically immobile.

History

Journal

Solid state ionics

Volume

53-56

Issue

Part 2

Pagination

1011 - 1026

Publisher

Elsevier

Location

Amsterdam, The Netherlands

ISSN

0167-2738

eISSN

1872-7689

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

1992, Elsevier Science B.V.