Dynamic Water Promotes Lithium-Ion Transport in Superconcentrated and Eutectic Aqueous Electrolytes

Jungyu Kim, Bonhyeop Koo, Joonhyung Lim, Jonggu Jeon, Chaiho Lim, Hochun Lee, Kyungwon Kwak, Minhaeng Cho

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


Superconcentrated aqueous electrolytes have shown promise as safe and high-voltage lithium-ion battery (LIB) electrolytes. However, the interplay of lithium-ion solvation structure and dynamics with fast Li-ion transport has not been elucidated yet. Here, we combine the ultrafast femtosecond mid-IR spectroscopy, dielectric relaxation spectroscopy, pulsed-field gradient NMR, and molecular dynamics simulation for investigating the solvation structure and Li-ion transport mechanism in superconcentrated aqueous electrolytes. We found the existence of water molecules with vibrational and rotational properties very similar to those of bulk water, even at extremely high salt concentrations (28 m). Our experimental results show that the electrolytes have a heterogeneous solvation environment, and bulk-like water molecules promote fast Li-ion transport. We anticipate that the molecular understanding of the superconcentrated aqueous electrolytes obtained here would facilitate the design of solvation structures to overcome the limit of dilute LIB electrolytes.

Original languageEnglish
Pages (from-to)189-196
Number of pages8
JournalACS Energy Letters
Issue number1
Publication statusPublished - 2022 Jan 14

Bibliographical note

Funding Information:
This work was supported by the Institute for Basic Science (IBS-R023-D1) (to M.C.) and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (NRF-2020R1A2C2010675, NRF-2020R1A2C1007504) (to K.K., H.L.).

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ASJC Scopus subject areas

  • Chemistry (miscellaneous)
  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Materials Chemistry


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