Three stages of hydrogen bonding network in DMF-water binary solution

Yang, Bo; Lang, Hongzhi; Liu, Zhe; Wang, Shenghan; Men, Zhiwei; Sun, Chia‐Chung

doi:10.1016/j.molliq.2020.114996

Cited by 27 publications

(23 citation statements)

References 37 publications

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“…In comparison, the hybrid 0.5 M ZnSO 4 –H 2 O–DMF electrolytes all fall below the bench line, attributed to a slight increase of salt association and increased size of Zn solvation shells upon the addition of “bulky” DMF (vs. H 2 O) that prevent independent motion of ions in the electrolytes. Raman peak shift of characteristic O–C–N scissor mode (σ(O–C–N), at around 665 cm –1 ) and C–N stretching mode (ν(C–N), at around 868 cm –1 ) upon the addition of ZnSO 4 into the DMF/H 2 O mixture (Figure b), suggests the interaction between Zn 2+ and DMF, which was further confirmed by the blue shift of CH 3 umbrella mode between Zn 2+ -free DMF/H 2 O mixtures and Zn 2+ -containing DMF/H 2 O mixtures in the ATR-FTIR spectra (Figure d). The strong hydrogen bonding between DMF and H 2 O can be demonstrated by the characteristic peak shift of pure DMF after the addition of H 2 O in the Raman spectra (Figure S14) and the ATR-FTIR spectra (Figure d and Figure S15), where the DMF/H 2 O interaction helps to break the hydrogen bonding network among free water molecules and suppress HER. ,, Meanwhile, the quantitative fitting of SO 4 2– resonance showed that the CIP fraction slightly increased with DMF contents in the hybrid electrolyte (Figure c and Table S6), consistent with the Walden plots analysis and the molecule dynamics (MD) result.…”

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confidence: 68%

Localized Hydrophobicity in Aqueous Zinc Electrolytes Improves Zinc Metal Reversibility

et al. 2022

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The rechargeability of aqueous zinc metal batteries is plagued by parasitic reactions of the zinc metal anode and detrimental morphologies such as dendritic or dead zinc. To improve the zinc metal reversibility, hereby we report a new solution structure of aqueous electrolyte with hydroxyl-ion scavengers and hydrophobicity localized in solvent clusters. We show that although hydrophobicity sounds counterintuitive for an aqueous system, hydrophilic pockets may be encapsulated inside a hydrophobic outer layer, and a hydrophobic anode–electrolyte interface can be generated through the addition of a cation-philic, strongly anion-phobic, and OH–-reactive diluent. The localized hydrophobicity enables less active water and less absorbed water on the Zn anode surface, which suppresses the parasitic water reduction; while the hydroxyl-ion-scavenging functionality further minimizes undesired passivation layer formation, thus leading to superior reversibility (an average Zn plating/stripping efficiency of 99.72% for 1000 cycles) and lifetime (80.6% capacity retention after 5000 cycles) of zinc batteries.

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confidence: 68%

Localized Hydrophobicity in Aqueous Zinc Electrolytes Improves Zinc Metal Reversibility

et al. 2022

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“…The existence of maxima at stoichiometric ratios indicates that the specific complex structure may be formed in the DMF–water mixtures. Many experimental techniques, such as NMR, , infrared spectroscopy, − dielectric relaxation spectroscopy, , Raman spectroscopy, , and so on, and theoretical methods ,− have been performed to elucidate the structure and dynamics of aqueous DMF mixtures. However, the underlying mechanism of the microheterogeneity in the mixture solution is not fully understood yet.…”

Section: Introductionmentioning

confidence: 99%

Distinct Hydrogen Bonding Dynamics Underlies the Microheterogeneity in DMF–Water Mixtures

et al. 2022

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The hydrogen bonding interaction between the amide functional group and water is fundamental to understanding the liquid–liquid heterogeneity in biological systems. Herein, the structure and dynamics of the N,N-dimethylformamide (DMF)–water mixtures have been investigated by linear and nonlinear IR spectroscopies, using the hydroxyl stretch and extrinsic probe of thiocyanate as local vibrational reporters. According to vibrational relaxation dynamics measurements, the orientational dynamics of water is not directly tied to those of DMF molecules. Wobbling-in-a-cone analysis demonstrates that the water molecules have varying degrees of angular restriction depending on their composition due to the formation of specific water–DMF networks. Because of the preferential solvation by DMF molecules, the rotational dynamics of the extrinsic probe is slowed significantly, and its rotational time constants are correlated to the change of solution viscosity. The unique structural dynamics observed in the DMF–water mixtures is expected to provide important insights into the underlying mechanism of microscopic heterogeneity in binary mixtures.

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“…Consequently, the blue shift of C-H stretching for DMF is attributed to the reformation of HB between the C=O group of DMF and H2O molecules. The FTIR spectrum also shows discernible blue-shift in the OH bending vibration at 1600~1700 cm -1 and red-shift in the OH stretching vibration at 3000~3500 cm -1 of H2O as the DMF content increases, verifying the reformation of HB between DMF and H2O 25 . Besides, the blue-shift in the C=O bending vibration of DMF (~1661 cm -1 ) could be observed in the hybrid electrolytes due to the HB between C=O and H2O.…”

Section: In Addition New Complexes Of Znmentioning

confidence: 81%

“…However, apparent recrystallization of ZnSO4 occurred when the H2O to DMF ratio increased up to 3:3, indicating that DMF was involved in the solvation structure of Zn 2+ with water and the excess DMF could damage it (Supplementary Figure 1 and Figure 1) 24 . Although DMF is dissolved in H2O in any proportion constructing an hydrogen bonding (HB), it is not readily soluble with ZnSO4 due to an antisolvent against aqueous ZnSO4 electrolyte 25,26 . Accordingly, the H2O to DMF ratio is controlled in the range of 6:0 to 2:4.…”

Section: Solution Structure Analysis Of Electrolytementioning

confidence: 99%

“…Moreover, the 17 O chemical shift showed a downshift from 4.56 ppm in ZnSO4-H2O electrolyte to 4.26 ppm in ZnSO4-H2O-DMF electrolyte, confirming that DMF could be incorporated 6 / 31 into the solvation structure of Zn 2+ with H2O (Supplementary Figure 6). The Raman spectra of H2O can be resolved into three component bands centered at 3229, 3409, and 3554 cm -1 , which are attributed to be symmetric and asymmetric OH stretching and the free OH of water, respectively (Figure 2h) 25 . Accordingly, the addition of DMF significantly breaks down the strong HB networks consisting of water as confirmed by the weakened OH stretching.…”

Section: In Addition New Complexes Of Znmentioning

confidence: 99%

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Solvation Structure and Interfacial Regulation for Extremely Stable Zinc Metal Anodes Operating in a Wide Range of Temperatures

Kang

Yao

Chen

et al. 2021

Preprint

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Aqueous zinc-metal batteries are promising for large-scale energy storage owing to their reasonable energy density, safety and low cost. However, their practical applications are limited by hydrogen evolution, corrosion, and dendrite formation of Zn anode and there is trade-off between efficiency and stability at high and low temperatures. Herein, we propose a solvation chemistry regulation strategy that can adjust the Zn2+-solvation structure and in situ form a robust and Zn2+-conducting Zn5(CO3)2(OH)6 SEI on the Zn surface, using hybrid electrolytes of water and a polar aprotic N, N-dimethylformamide. As verified by experimental characterizations and computational analyses, the unique solvation structure and the newly formed solid electrolyte interface are created by hybrid electrolytes, resulting in highly reversible and dendrite-free Zn plating/stripping process as well as thermal stability and high ionic conductivity from −30 to 70 °C. The Zn||Zn symmetric cells in hybrid electrolytes are very stable over 2500 h at 25 ℃ and 2000 h even at –20 ℃. Thus, the stability and reversibility of the hybrid zinc-ion capacitors with Zn metal anode in hybrid electrolytes are firstly achieved in a wide and extreme temperature range, demonstrating high capacity retentions and Coulombic efficiencies over 14000, 10000, and 600 cycles at 25, −20, and 70 ℃, respectively.

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Three stages of hydrogen bonding network in DMF-water binary solution

Cited by 27 publications

References 37 publications

Localized Hydrophobicity in Aqueous Zinc Electrolytes Improves Zinc Metal Reversibility

Localized Hydrophobicity in Aqueous Zinc Electrolytes Improves Zinc Metal Reversibility

Distinct Hydrogen Bonding Dynamics Underlies the Microheterogeneity in DMF–Water Mixtures

Solvation Structure and Interfacial Regulation for Extremely Stable Zinc Metal Anodes Operating in a Wide Range of Temperatures

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