Application of Ionic Liquids to Li Batteries

Sakaebe, Hikarí; Matsumoto, Hajime

doi:10.1002/0471762512.ch14

Cited by 9 publications

(9 citation statements)

References 18 publications

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“…We focus on the molecular scale effects of the local liquid structure at the interface between a charged electrode surface and an ionic liquid. Interfacial phenomena in ionic liquids are a subject of intensive ongoing research in many areas: from electrochemistry − to nanotribology − and from synthetic chemistry − to biomedical sciences − as well as in theoretical chemical physics. − The emerging interest in this problem is due to several reasons: on one hand, ionic liquids at charged interfaces are a key element of a number of (potential) applications, such as supercapacitors, batteries, − solar panels, electrolyte-gated electronics, and electrodeposition; ,, on the other hand, ionic liquids at charged interfaces reveal a number of (new) interesting effects, such as overscreening, lattice saturation, and electrostriction. ,,− At least in combination(s), these effects seem to be specific to the highly concentrated ionic liquid electrolytes. Consequently, these effects are not well-described by classical theories of the double layer (such as the Gouy–Chapman theory) that were developed for low-concentration electrolytes …”

Section: Introductionmentioning

confidence: 99%

Screening of Ion–Graphene Electrode Interactions by Ionic Liquids: The Effects of Liquid Structure

2014

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We have investigated the screening of solute ion−electrode interactions in two ionic liquids (1-butyl 3-methylimidazolium tetrafluoroborate [BMIm][BF 4 ] and 1,3dimethylimidazolium chloride [MMIm]Cl) by constructing free energy profiles for dissolved charged probes as a function of distance from a charged surface (graphene). The free energy profiles for three types of mutual interactions (surface and solute with opposite charges, solute and uncharged surface, and surface and solute with the same charges) differ from each other, but are remarkably similar in the two ionic liquids. They all show oscillations rather than the monotonic behavior predicted by Debye-type screening models. In both ionic liquids, there are high barriers impeding the motion of charged probes to the oppositely charged surface. We examined the local liquid structure around the probes and found that the free energy minima correspond to positions in which the solvation layers induced by the surface charge and the solvation shells around the probes enhance each other while barriers occur where they perturb each other.

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Section: Introductionmentioning

confidence: 99%

Screening of Ion–Graphene Electrode Interactions by Ionic Liquids: The Effects of Liquid Structure

2014

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“…Ionic liquids (ILs) composed of the perfluoro anion, such as BF 4 – and bis(trifluoromethylsulfonyl)amide ([(CF 3 SO 2 ) 2 N] − , Tf 2 N – ), and onium cations, such as 1-ethyl-3- methylimidazolium (C 2 mim + ) and aliphatic quaternary ammonium, have been already significantly studied as one of the candidates for such less-flammable electrolytes. For example, aliphatic quaternary ammonium based ILs exhibited a large electrochemical window (over 5 V), which allows us to use a lithium metal anode without any additives and a high voltage positive electrode, such as LiCoO 2 . However, the onium cations in the ILs have no significant role in the charge and/or discharge process in a lithium battery system except for maintaining the ILs in the liquid state.…”

Section: Introductionmentioning

confidence: 99%

Investigation of an Intermediate Temperature Molten Lithium Salt Based on Fluorosulfonyl(trifluoromethylsulfonyl)amide as a Solvent-Free Lithium Battery Electrolyte

Kubota¹,

Matsumoto²

2013

J. Phys. Chem. C

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The asymmetric amide anion, such as (fluorosulfonyl)(trifluoromethylsulfonyl)amide (fTfN–), formed intermediate temperature molten lithium salts at 100 °C, which was the lowest among the lithium single molten salts composed of conventional halogenide, nitrate, perchlorate, and perfluoro anions. The molten Li[fTfN] was highly viscous (17 Pa·s at 110 °C, however, it was classified as a good ionic liquid by Walden plot analysis, which indicates the good-dissociation between Li+ and fTfN–. Due to the high transport number of the lithium cation (0.94), the Li[fTfN] behaves as a single lithium-ion conducting material. The Li[fTfN] possesses an electrochemical window (5.0 V) due to the oxidative resistance of the perfluoro anion. The charge and discharge for a conventional composite positive electrode containing LiCoO2 or LiFePO4 was successful. In particular, LiFePO4 showed a high capacity and Coulombic efficiency at 0.1–5 C.

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“…However, the liquid electrolytes leave a margin for improvement considering their productivity and compatibility with composite electrodes, which cannot be combined with the solid electrolytes. To improve the safety of the liquid electrolytes, room-temperature ionic liquids (RTILs) have attracted much interest due to their nonflammability and low vapor pressure . On the basis of such a background, we have attempted to develop a low-melting lithium molten salt, which melts below the melting point of the lithium metal (180 °C), as the electrolyte without any organic solvent or organic cation of the RTIL.…”

Section: Introductionmentioning

confidence: 99%

Diffusion of Lithium Cation in Low-Melting Lithium Molten Salts

et al. 2018

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The self-diffusion coefficients of the lithium cation (D(Li + )) and counteranion (D(anion)) in the molten lithium amide, such as lithium bis(fluorosulfonyl)amide (Li [FSA]) and lithium fluorosulfonyl(trifluoromethylsulfonyl)amide (Li[FTA]), were measured by a pulsed-gradient spin− echo nuclear magnetic resonance method at 150 °C. In the relationships between viscosity and the resulting self-diffusion coefficient (the D(Li + ) is 1.4 × 10 −11 m 2 •s −1 and the D(anion) is 5.5 × 10 −12 m 2 •s −1 for the Li[FSA] and the D(Li + ) is 1.7 × 10 −12 m 2 •s −1 and the D(anion) is 6.6 × 10 −13 m 2 •s −1 for the Li[FTA]), the Li[FTA] and Li [FSA] have a stronger intercalation between ions than the high-temperature lithium molten salts. However, their ionic conductivities are higher than those estimated by D(Li + ) and D(anion); specifically, that of the Li[FTA] is three times higher. Therefore, the Li[FTA] would have special conductive behavior, which leads to the superionic nature of the Walden plot and the high rate performance against much higher viscosity in lithium secondary battery. Such unique conduction and battery behaviors using the Li[FTA] might be due to the robust and asymmetric structure of the FTA − .

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Application of Ionic Liquids to Li Batteries

Cited by 9 publications

References 18 publications

Screening of Ion–Graphene Electrode Interactions by Ionic Liquids: The Effects of Liquid Structure

Screening of Ion–Graphene Electrode Interactions by Ionic Liquids: The Effects of Liquid Structure

Investigation of an Intermediate Temperature Molten Lithium Salt Based on Fluorosulfonyl(trifluoromethylsulfonyl)amide as a Solvent-Free Lithium Battery Electrolyte

Diffusion of Lithium Cation in Low-Melting Lithium Molten Salts

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