Why Does Dimethyl Carbonate Dissociate Li Salt Better Than Other Linear Carbonates? Critical Role of Polar Conformers

Hyejin Lee, Sunwook Hwang, Minju Kim, Kyungwon Kwak, Jaeho Lee, Young Kyu Han, Hochun Lee

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The marked difference in the ionic conductivities of linear carbonate (LC) electrolyte solutions despite their similar viscosities and permittivities is a long-standing puzzle. This study unraveled the critical impact of solvent conformational isomerism on salt dissociation in 0.1-3.0 M LiPF6 dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) solutions using Raman and dielectric relaxation spectroscopies. The extent of salt dissociation in the LC solutions, which decreased in the order DMC > EMC > DEC, is closely related to the fraction of polar cis-trans LC conformers, as this conformer participates in Li ion solvation more readily than the nonpolar cis-cis counterpart. Our first-principles calculations corroborated that the cis-trans conformer facilitates free ion formation more than the cis-cis conformer, and the extent of this effect decreased in the order DMC > EMC > DEC. This study provides an avenue for the design of highly conductive electrolytes by exploiting the conformational isomerism of solvent molecules.

Original languageEnglish
Pages (from-to)10382-10387
Number of pages6
JournalJournal of Physical Chemistry Letters
DOIs
Publication statusAccepted/In press - 2020

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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