TY - JOUR
T1 - Why Does Dimethyl Carbonate Dissociate Li Salt Better Than Other Linear Carbonates? Critical Role of Polar Conformers
AU - Lee, Hyejin
AU - Hwang, Sunwook
AU - Kim, Minju
AU - Kwak, Kyungwon
AU - Lee, Jaeho
AU - Han, Young Kyu
AU - Lee, Hochun
N1 - Publisher Copyright:
© 2020 American Chemical Society.
PY - 2020/12/17
Y1 - 2020/12/17
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85097798763&partnerID=8YFLogxK
U2 - 10.1021/acs.jpclett.0c03235
DO - 10.1021/acs.jpclett.0c03235
M3 - Article
C2 - 33237787
AN - SCOPUS:85097798763
SN - 1948-7185
VL - 11
SP - 10382
EP - 10387
JO - Journal of Physical Chemistry Letters
JF - Journal of Physical Chemistry Letters
IS - 24
ER -