ACS_Energy LETTERS
January 14, 2022
Volume 7, Issue 1
Pages 1-559
Dynamic Water Promotes Lithium-Ion Transport in Superconcentrated and Eutectic Aqueous Electrolytes
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.
- Jungyu Kim
- Bonhyeop Koo
- Joonhyung Lim
- Jonggu Jeon
- Chaiho Lim
- Hochun Lee
- Kyungwon Kwak
- Minhaeng Cho
ACS Energy Letters | Vol 7, No 1
Image created by minjeong Kim / Nanosphere
ACS_Energy LETTERS
January 14, 2022
Volume 7, Issue 1
Pages 1-559
Dynamic Water Promotes Lithium-Ion Transport in Superconcentrated and Eutectic Aqueous Electrolytes
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.
ACS Energy Letters | Vol 7, No 1
Image created by minjeong Kim / Nanosphere