Molecular relaxation of lithium salts in 2-methyltetrahydrofuran at 25.degree.C

Delsignore, M.; Maaser, H. E.; Petrucci, Sergio

doi:10.1021/j150655a045

Cited by 29 publications

(18 citation statements)

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“…This behavior has been observed before in electrolyte solutions prepared with non-polar (low dielectric constant) solvents. 37,38 Consequently, at low salt concentrations, the low dielectric constant of the solution results in the formation of electrically neutral ion pairs or aggregates.…”

Section: Resultsmentioning

confidence: 99%

Some Physical Properties of Ethylene Carbonate-Free Electrolytes

Xiong

Bauer

Ellis

et al. 2018

J. Electrochem. Soc.

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Physical properties of LiPF 6 in ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) electrolytes were studied by conductivity measurements, Fourier transform infrared spectroscopy (FT-IR) and differential thermal analysis (DTA). Conductivity measurements show that the addition of additive levels of FEC to EMC electrolyte can dramatically increase the conductivity of EC-free EMC electrolytes at low salt concentrations below 0.4 M. FT-IR results show that the added FEC hinders ion pair formation by competing with EMC to dissociate LiPF 6 resulting in increased conductivity in EMC electrolytes. Conductivity measurements show that the conductivity of DMC electrolytes decreases significantly below 0 • C due to the high melting point of DMC. Differential thermal analysis was used to determine the LiPF 6 -DMC phase diagram which then can be used to explain the conductivity results. The results presented here identify avenues by which EC-free electrolytes can be improved for use in practical Li-ion cells. Li-ion battery packs for electrified vehicles and grid energy storage require high energy density and long lifetime cells.1-3 One approach to increase the energy density of Li-ion cells is to adopt high potential positive electrodes. Layered Li[Ni x Mn y Co 1-x-y ]O 2 materials have been extensively investigated since they are cheaper alternatives to LCO and since they can function at high potentials. 4-9However, it is a great challenge to cycle high voltage NMC cells (above 4.3V) well. The use of new solvent blends and the introduction of electrolyte additives are two common ways to improve the lifetime of high voltage NMC Li-ion cells. 24-32 Therefore, it is important to study the physical properties of EC-free electrolytes to optimize the performance of cells where EC-free electrolytes are used.Differential scanning calorimetry (DSC) 29,32,33 and differential thermal analysis (DTA) 34 can be used to examine the phase diagrams of solvent blends and of electrolytes. Ding et al. showed that supercooling and superheating during DSC measurements for phase diagram determination could be dramatically reduced if carbon black and/or electrode powders were present in the samples during measurement. 33Recently Day et al. demonstrated that the DTA technique can be applied to an entire Li-ion cell and is a non-invasive in-situ method to probe the state of the liquid electrolyte within intact Li-ion cells. 34The DTA measurements provide information about the amount of liquid electrolyte remaining in the cell and about the electrolyte composition. The interpretation of the DTA results requires information about the phase diagram of the electrolyte of interest. However, the phase diagrams of LiPF 6 :ethyl methyl carbonate and LiPF 6 :dimethyl carbonate electrolytes have not yet been reported.In this report, the conductivity of LiPF 6 :EMC electrolytes with various salt concentrations were measured over a wide range of temperatures. Fourier transform infrared spectroscopy (FT-IR) was used to study the interactions between t...

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Section: Resultsmentioning

confidence: 99%

Some Physical Properties of Ethylene Carbonate-Free Electrolytes

Xiong

Bauer

Ellis

et al. 2018

J. Electrochem. Soc.

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“…Li + ) or d-d splitting of the transition metal ions, if any. (53,54) The absorption spectrum of BPT showed the lowest energy absorption maximum at 285 nm in methanol, the π-π * transition of the triazole substituted phenol rings (Fig. 7).…”

Section: O-h H8 H10 H12 H13 H11 O-h H8 H10 H12 H11 H13mentioning

confidence: 99%

Spectroscopic investigation of bis-appended 1,2,3-triazole probe for the detection of Cu(II) ion

Ghosh

Rhodes

Winder

et al. 2017

Journal of Molecular Structure

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A novel bis-1,4-disubstituted-1,2,3-triazole chemosensor, accessed with "Click Chemistry", was probed for its recognition of metal ions. The interaction of the sensor with various cation analytes was investigated by 1 H-NMR, UV-Vis absorption and fluorescence spectroscopy. The bis-triazole is selective for Cu(II) with a detection limit in the micromolarconcentration range and a clear to yellow colorimetric response that is exclusive to that ion is observed. The stoichiometry of probe to Cu(II), 2 : 1, was determined with Job's plots based on titration studies using UV-absorption and 1 H-NMR spectroscopy. Computational and spectroscopic investigations revealed that the sensor binds to Cu(II) via its triazole units. Keywords: , there are less reports for bis-triazole sensors that provide a colorimetric signal.(43) Additionally, in many instances the bistriazole sensors fail to respond exclusively to Cu(II).(31, 34, 37, 38) Herein, we report the synthesis of a novel bis-1,2,3triazole sensor appended with phenolic groups, (2,2-bis((1-(2hydroxyphenyl)-1H-1,2,3-triazol-4-yl)methyl)-5,5dimethylcyclohexane-1,3-dione) (BPT) (Scheme 1). BPT exhibits a selective colorimetric response to copper(II), clear to yellow. To verify the selectivity, BPT was screened against an series of metal ions

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“…Electrolyte solutions relevant for lithium batteries were investigated by Lestrade t a1. (13,48), and Petrucci t ct. (15)(16)(17)(18)(19)(20)(21).…”

Section: = (T5(o)/e0) (Ta + T_a_) (13c)mentioning

confidence: 99%

Dielectric properties of nonaqueous electrolyte solutions

Barthel¹,

Buchner²

1986

Pure and Applied Chemistry

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-High frequency permittivity of non-aqueous electrolyte solutions and their solvents is discussed in the framework of time domain and frequency domain methods. Evaluation of data is performed on the basis of models presupposing one or more relaxation processes. Depression of the solvent permittivity, relaxation times of the solvent molecules, and dispersion amplitudes and relaxation times of ion-pair relaxation are investigated with regard to actual theories underlying these phenomena. Information is obtained on structural and dynamical properties of classes of electrolyte solutions based on rotic H-bonding, dipolar aprotic, and low permittivity solvents and mixtures of solvents.

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Molecular relaxation of lithium salts in 2-methyltetrahydrofuran at 25.degree.C

Cited by 29 publications

References 0 publications

Some Physical Properties of Ethylene Carbonate-Free Electrolytes

Some Physical Properties of Ethylene Carbonate-Free Electrolytes

Spectroscopic investigation of bis-appended 1,2,3-triazole probe for the detection of Cu(II) ion

Dielectric properties of nonaqueous electrolyte solutions

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