Ternary mixtures of ionic liquids for better salt solubility, conductivity and cation transference number improvement

Karpierz, E.; Niedzicki, Leszek; Trzeciak, Tomasz; Zawadzki, Maciej; Dranka, Maciej; Zachara, Janusz; Żukowska, G.Z.; Bitner-Michalska, Anna; Wieczorek, W.

doi:10.1038/srep35587

Cited by 19 publications

(14 citation statements)

References 19 publications

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“…A gradual increase in ion aggregates with increasing salt concentration, coupled with a concomitant increase in viscosity, was considered to be the main reason for reduced ionic conductivity in many ionic liquid-based or polymer-based electrolytes. Indeed, for the concentrations usually of interest in electrolytes, this hypothesis has been confirmed both experimentally and theoretically. − However, when the salt concentration exceeds this “normal” range (typically 0.5–1.0 mol kg –1 ), both the structural and dynamic picture may be different. This is what we want to investigate further here.…”

Section: Resultsmentioning

confidence: 89%

Na-Ion Solvation and High Transference Number in Superconcentrated Ionic Liquid Electrolytes: A Theoretical Approach

2017

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Ionic liquids have been extensively studied for developing next-generation Li- and Na-ion batteries because they are potentially safer replacements for conventional organic solvents in liquid electrolytes. Some recent work has drawn our attention to high lithium and sodium salt concentration ionic liquid systems which demonstrate high alkali-metal-ion transference numbers and support cycling at high current densities. Here we present an in-depth theoretical study of ion dynamics in a concentrated room-temperature ionic liquid, N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide ([C3mpyr][FSI]) with a sodium salt (NaFSI), focusing on how the solvation structure of a Na ion changes with salt concentration and how this affects its dynamics. These findings will help to understand the behavior of superconcentrated ionic liquid materials that will guide experimentalists in optimizing ionic liquid-based electrolyte materials.

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Section: Resultsmentioning

confidence: 89%

Na-Ion Solvation and High Transference Number in Superconcentrated Ionic Liquid Electrolytes: A Theoretical Approach

2017

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“…In commercial LIB, electrolytes of 1 M salt concentration are commonly used for reasons of optimal performance. , Electrolytes of higher concentrations have not been explored much given their poor ionic conductivity. However, recent experimental studies on concentrated electrolytes (e.g., 4.2 M solution of lithium bis(trisfluoromethanesulphonyl)azanide [LiTFSA] in acetonitrile) show that the concentrated solutions offer extremely good thermal and reactive stabilities. , This has led to research on concentrated electrolytes as an alternative to the current electrolyte technology. , Research into identification of cosolvents, additives, new solvent, and salt materials is to be pursued to make the concentrated electrolytes a viable option for advanced batteries by improving their transport properties. , …”

Section: Introductionmentioning

confidence: 99%

“…18,19 Research into identification of cosolvents, additives, new solvent, and salt materials is to be pursued to make the concentrated electrolytes a viable option for advanced batteries by improving their transport properties. 14,20 In the current LIB technology, EC solvent of the electrolytic solution plays a crucial role. 21 It has good dielectric properties enabling better dissociation of the salt into ions.…”

Section: ■ Introductionmentioning

confidence: 99%

Effect of Salt Concentration on Properties of Lithium Ion Battery Electrolytes: A Molecular Dynamics Study

2018

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Electrolyte solutions of 1 M concentration are typically used in lithium ion batteries (LIB) for optimal performance. However, recently, superconcentrated electrolytes have been proposed to be a promising alternative to 1 M solutions. Despite their improved stability features, application of the concentrated electrolytes is hindered by their poor transport properties. We probe EC-LiPF 6 electrolyte system for a range of concentrations: 0.06 to 4 M using molecular dynamics simulations to study the effect of concentration on transport and structural properties. Molecular structure of the solution changes with concentration from a predominantly solvent separated ion pair (SSIP) configuration at the dilute limit to an aggregate rich configuration at high concentration. Depletion of SSIPs and formation of more aggregates at higher concentrations affect the transport properties. The present work provides insights into the relation between molecular structure and performance of the electrolyte solution and suggests ways to design novel concentrated electrolytes.

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“…An appropriate organic solvent is critically important not only for the dissolution of lithium orthoborate salt but also for oxidative stability, thermally stability, satisfactory conductivity, cell performance and life cycle 28 .Ether based organic solvents (also known as glymes) are gaining attentions in lithium ion batteries due to a number of advantages such as low viscosity, high thermal stability and safety 29 , 30 . Recently, a number of studies have demonstrated that mixtures of ionic liquids and glymes possess excellent electrolyte properties and are promising solvents for lithium-ion batteries 31 – 35 .…”

Section: Introductionmentioning

confidence: 99%

Transport and Association of Ions in Lithium Battery Electrolytes Based on Glycol Ether Mixed with Halogen-Free Orthoborate Ionic Liquid

Shah

Гнездилов

Gusain

et al. 2017

Sci Rep

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Ion transport behaviour of halogen-free hybrid electrolytes for lithium-ion batteries based on phosphonium bis(salicylato)borate [P4,4,4,8][BScB] ionic liquid mixed with diethylene glycol dibutyl ether (DEGDBE) is investigated. The Li[BScB] salt is dissolved at different concentrations in the range from 0.15 mol kg−1 to 1.0 mol kg−1 in a mixture of [P4,4,4,8][BScB] and DEGDBE in 1:5 molar ratio. The ion transport properties of the resulting electrolytes are investigated using viscosity, electrical impedance spectroscopy and pulsed-Field Gradient (PFG) NMR. The apparent transfer numbers of ions are calculated from the diffusion coefficients measured by using PFG NMR. PFG NMR data suggested ion association upon addition of Li salt to the [P4,4,4,8][BScB] in DEGDBE solution. This is further confirmed by liquid state 7Li and 11B NMR, and FTIR spectroscopic techniques, which suggest strong interactions between the lithium cation and oxygen atoms of the [BScB]− anion in the hybrid electrolytes.

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Ternary mixtures of ionic liquids for better salt solubility, conductivity and cation transference number improvement

Cited by 19 publications

References 19 publications

Na-Ion Solvation and High Transference Number in Superconcentrated Ionic Liquid Electrolytes: A Theoretical Approach

Na-Ion Solvation and High Transference Number in Superconcentrated Ionic Liquid Electrolytes: A Theoretical Approach

Effect of Salt Concentration on Properties of Lithium Ion Battery Electrolytes: A Molecular Dynamics Study

Transport and Association of Ions in Lithium Battery Electrolytes Based on Glycol Ether Mixed with Halogen-Free Orthoborate Ionic Liquid

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