Anionic effects on the structure and dynamics of water in superconcentrated aqueous electrolytes

Han, Sungho

doi:10.1039/c8ra09589b

Cited by 31 publications

(40 citation statements)

References 66 publications

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“…In the opposite order, higher probability for no such bonds, again indicating fewer water clusters, is found. [ 41 ]…”

Section: Resultsmentioning

confidence: 99%

“…[ 45–48 ] Due to their higher charge density, kosmotropic anions also have a stronger tendency than chaotropic anions to form ion pairs with solution cations, resulting in a more intact hydrogen‐bonding network. [ 41 ] In other words, kosmotropic anions compete with water for a place in the cation solvation shell, thus freeing water molecules from this crucial trap, which is at least in part responsible for the high overpotentials toward water electrolysis in water‐in‐salt electrolytes. [ 41 ] Note that at sufficiently high concentration, chaotropes are also incorporated into the cation solvation shell, which is considered a key requirement for the formation of an anion‐derived SEI.…”

Section: Resultsmentioning

confidence: 99%

“…Molecular dynamics studies revealed that in concentrated solutions water–cation, water–water, and cation–anion interactions, i.e., ion‐pairing and agglomeration, are highly sensitive to the nature of the anion. [ 41 ] The influence of the anion on solution structure was recently also studied experimentally for saturated solutions of NaClO 4 , NaOTf, LiTFSI, NaNO 3 , and Na 2 SO 4 . However, the large range of saturation concentrations for these salts (1 to 17m) makes comparison of the results for the different anions difficult.…”

Section: Introductionmentioning

confidence: 99%

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Anion Selection Criteria for Water‐in‐Salt Electrolytes

Reber

Grissa

Becker

et al. 2020

Advanced Energy Materials

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Water‐in‐salt electrolytes have enabled the development of novel high‐voltage aqueous lithium‐ion batteries. This study explores the reasons why analogous sodium electrolytes have struggled to reach the same level of electrochemical stability. Solution structure and electrochemical stability are compared for 11 sodium salts, selected among the major classes of salts proposed for highly concentrated electrolytes. The water environment established for each anion is related to its position in the Hofmeister series and a surprisingly strong correlation between the chaotropicity of the anion and the resulting electrochemical stability of the electrolyte is found. The search for suitable sodium salts is complicated by the fact that higher salt concentrations are needed than for their lithium equivalents. Reaching such a high concentration of >25 mol kg−1 with one or a combination of multiple sodium salts that have the desired properties remains a major challenge. Hence, alternative approaches such as multisolvent systems should be explored. The water solubility of NaTFSI can be increased from 8 to 30 mol kg−1 in the presence of ionic liquids. Such a ternary electrolyte enables stable cycling of a 2 V class sodium‐ion battery based on the NaTi2(PO4)3/Na2Mn[Fe(CN)6] electrode couple for 300 cycles at 1C with a Coulombic efficiency of >99.5%.

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“…In the opposite order, higher probability for no such bonds, again indicating fewer water clusters, is found. [ 41 ]…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Anion Selection Criteria for Water‐in‐Salt Electrolytes

Reber

Grissa

Becker

et al. 2020

Advanced Energy Materials

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“…To examine how the solvation dynamics of a Li + ion is related with the motions of solvents, we consider the translational and rotational dynamics of EC and DMC. For the translational motion, we calculate the translational mean square displacement (TMSD) 15,28,29,39–42 ,…”

Section: Resultsmentioning

confidence: 99%

Structure and dynamics in the lithium solvation shell of nonaqueous electrolytes

Han

2019

Sci Rep

Self Cite

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The solvation of a lithium ion has been of great importance to understand the structure and dynamics of electrolytes. In mixed electrolytes of cyclic and linear carbonates, the lithium solvation structure and the exchange dynamics of solvents strongly depend on the mixture ratio of solvents, providing a connection of the rigidity of the lithium solvation shell with the solvent composition in the shell. Here we study the dynamical properties of solvents in the solvation sheath of a lithium ion for various solvent mixture ratios via molecular dynamics simulations. Our results demonstrate that the exchange dynamics of solvents exhibits a non-monotonic behavior with a change in the mixture ratio, which keeps preserved on both short and long time scales. As the fraction of cyclic carbonate increases, we find that the structural properties of cyclic and linear carbonates binding to a lithium ion show different responses to a change in the fraction. Furthermore, we find that the rotational dynamics of cyclic carbonate is relatively insensitive to the mixture ratio in contrast to the rotational dynamics of linear carbonate. Our results further present that an anion shows different properties in structure and dynamics from solvents upon changing the mixture ratio of solvents.

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“…The ion–dipole interaction force is less strong because it involves formally and partially charged particles. Finally, dipole–dipole interaction acts between partially charged water dipoles and, thus, it is the weakest 57 . However, water molecules have polarity, and they actively interact with microwaves.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Visualization of microwave near-field distribution in sodium chloride and glucose aqueous solutions by a thermo-elastic optical indicator microscope

Baghdasaryan

Babajanyan

Odabashyan

et al. 2021

Sci Rep

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In this study, a new optical method is presented to determine the concentrations of NaCl and glucose aqueous solutions by using a thermo-elastic optical indicator microscope. By measuring the microwave near-field distribution intensity, concentration changes of NaCl and glucose aqueous solutions were detected in the 0–100 mg/ml range, when exposed to microwave irradiation at 12 GHz frequency. Microwave near-field distribution intensity decreased as the NaCl or glucose concentration increased due to the changes of the absorption properties of aqueous solution. This method provides a novel approach for monitoring NaCl and glucose in biological liquids by using a CCD sensor capable of visualizing NaCl and glucose concentrations without scanning.

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Anionic effects on the structure and dynamics of water in superconcentrated aqueous electrolytes

Abstract: The effects of anions on the properties of water are examined for various salt concentrations.

Cited by 31 publications

References 66 publications

Anion Selection Criteria for Water‐in‐Salt Electrolytes

Anion Selection Criteria for Water‐in‐Salt Electrolytes

Structure and dynamics in the lithium solvation shell of nonaqueous electrolytes

Visualization of microwave near-field distribution in sodium chloride and glucose aqueous solutions by a thermo-elastic optical indicator microscope

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