Solvation Structure around Li+Ions in Organic Carbonate Electrolytes: Spacer-Free Thin Cell IR Spectroscopy

Chaiho Lim, Joo Hyun Kim, Yeongseok Chae, Kyung Koo Lee, Kyungwon Kwak, Minhaeng Cho

Research output: Contribution to journalArticlepeer-review

Abstract

Organic carbonate electrolytes are widely used materials for lithium-ion batteries. However, detailed solvation structures and solvent coordination numbers (CNs) of lithium cations in such solutions have not been accurately described nor determined yet. Because transmission-type IR spectroscopy is not of use for measuring the carbonyl stretch modes of electrolytes due to their absorption saturation problem, we here show that simple spacer-free thin cell IR spectroscopy can provide quantitative information on the number of solvating carbonate molecules around each lithium ion. We could estimate the solvent (carbonate) CNs of lithium ions in dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, propylene carbonate, and butylene carbonate over a wide range of lithium salt concentrations accurately, and they are compared with the previous results obtained with attenuated total reflection IR spectroscopy technique. We anticipate that our spacer-free thin cell approach will potentially be used to investigate the solvation dynamics, chemical exchange process, and vibrational energy transfers between solvating carbonate molecules in lithium salt electrolytes when combined with time-resolved IR spectroscopy.

Original languageEnglish
Pages (from-to)12594-12601
Number of pages8
JournalAnalytical chemistry
Volume93
Issue number37
DOIs
Publication statusPublished - 2021 Sep 21

ASJC Scopus subject areas

  • Analytical Chemistry

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