Ionic Association of Some Lithium Salts in 1,2-Dimethoxyethane. A Raman Spectroscopic and Conductivity Study

Muhuri, Prakash K.; Das, Bijan; Hazra, Dilip K.

doi:10.1021/jp963747d

Cited by 60 publications

(44 citation statements)

References 23 publications

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“…3 Direct comparison between theory and experiment for PEO:LiCl and PEO:LiTriflate in Fig. 1B is not possible, as ion-pairing occurs even at the lowest concentrations that have been experimentally studied. 19,24,25 Fig. 2 examines the molecular basis for the preferential anion diffusion in PEO.…”

mentioning

confidence: 99%

Enhancing Cation Diffusion and Suppressing Anion Diffusion via Lewis-Acidic Polymer Electrolytes

Savoie

Webb

Miller

2017

J. Phys. Chem. Lett.

125

118

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Solid polymer electrolytes (SPE) have the potential to increase both the energy density and stability of lithium-based batteries, but low Li + conductivity remains a barrier to technological viability. 1, 2 SPEs are designed to maximize Li + diffusivity relative to the anion, while maintaining sufficient salt solubility.It is thus remarkable that polyethylene oxide (PEO), the most widely used SPE, exhibits Li + diffusivity that is an order of magnitude smaller than that of typical counter-ions, such as TFSI − , at moderate salt concentrations. 3, 4 Here, we show that Lewis-basic polymers like PEO intrinsically favor slow cation and rapid anion diffusion while this relationship can be reversed in Lewis-acidic polymers.Using molecular dynamics (MD) simulations, Lewis-acidic polyboranes are identified that achieve up to a ten-fold increase in Li + diffusivity and a significant decrease in anion diffusivity, relative to PEO. The results for this new class of Lewis-acidic SPEs illustrate a general principle for increasing Li + diffusivity and transference number with polymer chemistries that exhibit weaker cation and stronger anion coordination. Savoie, Webb, and Miller -2 PEO-based materials are among the most successful SPEs, with net conductivities on the order of 10 −4 − 10 −3 S · cm −1 at ambient temperature. 5,6 However, net conductivity actually overstates electrolyte performance, since only Li + typically participates in the electrode chemistries in lithium-based batteries (Fig. 1A). Measurements of the Li + transference number, T Li (the ratio of Li + conductivity to the total conductivity), show that anions are responsible for most of the conductivity in PEO, 7-9 and ion diffusivity measurements reveal that anion diffusivity is an order of magnitude larger than Li + diffusivity for common salts at typical concentrations. 3, 4 Most strategies for increasing T Li have focused on immobilizing the anion, 10-13 while the primary strategy for increasing overall diffusion rates has been to decrease the glass-transition temperature, T g , of the polymer. 5, 6 However, neither approach addresses the fundamental ion-polymer interactions that are responsible for asymmetric cation and anion conduction.The major finding of this work is that the low Li + diffusivity and high anion diffusivity that characterize PEO-based SPEs can be reversed to favor Li + conduction in Lewis-acidic polymers. In conventional SPEs based on polyethers and other Lewis-basic units, salt solubility is driven by strong cation-polymer interactions. 11,14,15 However, this preferential coordination of cations leads to both the high relative diffusivity of weakly coordinated anions and the low diffusivity of Li + (Fig. 1B). The trade-off between strong cation coordination and diffusivity suggests that the strategy of driving salt solubility with relatively stronger anion-polymer interactions and weaker cation-polymer interactions may enhance SPE performance. To investigate this trade-off, we present over 100 microseconds of MD simulations to charact...

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mentioning

confidence: 99%

Enhancing Cation Diffusion and Suppressing Anion Diffusion via Lewis-Acidic Polymer Electrolytes

Savoie

Webb

Miller

2017

J. Phys. Chem. Lett.

125

118

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“…where x represents the molarity of ion-pair in equilibrium (4). (14) In order to calculate the value of K sp(th) , we need the value of ± .…”

Section: Estimation Of Dielectric Constant Of the Mixed Solventmentioning

confidence: 99%

“…As we know, ion association has an important role in chemical, biological and agricultural systems like colloids, proteins, soils, corrosion and lithium batteries. So, the ion association has been investigated widely experimentally and theoretically [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. When two ions of opposite charges approach enough each others an ion-pair species may be formed due to the coulombic attraction.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic Investigation of NaClO3 Solubility in the Mixed Solvent Medium and the Related Ion – Pair Formation at Different Temperatures

Aghaie¹,

Kishani²

2015

J. Appl. Sol. Chem. Model.

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Using the evaporating method, the solubility of sodium chlorate was determined in the various mixed solvents (water + ethanol + propanol) at various temperatures. The results showed that the solubility of NaClO3 decreases with increasing the mass percent of ethanol and propanol. On the other hand, the solubility of NaClO3 increases with increasing the temperature .In addition, the equilibrium constant of ion pair formation, KIP, for the reaction Na + (aq) + ClO3 -(aq) Na + ClO3 -(Ion Pair) was estimated upon Fuoss contact ion pair model and then, the values of ion-pair concentrations were determined by using the extended Debye-Hückel model and iteration calculations in various mixed solvents and various temperatures . Finally the value of thermodynamic solubility product constant, Ksp(th), and the values of H , S° and G°of ion-pair formation were estimated in the mixed solvent media.

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“…The conductometric method is well-suited to investigate the ion-solvent and ion-ion interactions in electrolyte solutions [1][2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Conductivity Study of Some Thiocyanate Salts in Aqueous Binary Mixtures of Tetrahydrofuran and 1,3-Dioxolane at 298.15 K

Chanda¹,

Roy²

2010

Zeitschrift Für Physikalische Chemie

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Electrical conductance measurements are reported for different thiocyanate salts, viz. ammonium thiocyanate (NH 4 CNS), sodium thiocyanate (NaCNS) and potassium thiocyanate (KCNS), sodium bromide (NaBr), sodium tetraphenylborate (NaBPh 4 ) and tetrabutylammonium bromide (Bu 4 NBr) in different mole fraction of water-tetrahydrofuran (THF) and water-1,3-dioxolane (1,3-DXL) binary mixtures at 298.15 K. The conductance data have been analyzed by the Fuoss conductance equation in terms of the limiting molar conductance (Λ 0 ), the association constant (K A ) and the association diameter (R). The limiting ionic conductances have been estimated from the appropriate division of the limiting molar conductivity value of the "reference electrolyte" Bu 4 NBPh 4 . Slight ionic association was found for all these electrolytes in these solvent mixtures. The results have been interpreted in terms of the formation of ion-pairs of ion-solvent interactions and structural changes in the mixed solvents.

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Ionic Association of Some Lithium Salts in 1,2-Dimethoxyethane. A Raman Spectroscopic and Conductivity Study

Cited by 60 publications

References 23 publications

Enhancing Cation Diffusion and Suppressing Anion Diffusion via Lewis-Acidic Polymer Electrolytes

Enhancing Cation Diffusion and Suppressing Anion Diffusion via Lewis-Acidic Polymer Electrolytes

Thermodynamic Investigation of NaClO3 Solubility in the Mixed Solvent Medium and the Related Ion – Pair Formation at Different Temperatures

Conductivity Study of Some Thiocyanate Salts in Aqueous Binary Mixtures of Tetrahydrofuran and 1,3-Dioxolane at 298.15 K

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