Infrared and Raman study of the PEO-LiTFSI polymer electrolyte

Rey, I.; Lassègues, J.C.; Grondin, Joseph; Servant, Laurent

doi:10.1016/s0013-4686(97)10092-5

Cited by 262 publications

(292 citation statements)

References 11 publications

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“…Apparently the splitting between the two bands (at $411 and $403 cm À1 ) is not so large for the case of the 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide liquid. The symmetric CF 3 stretching and deformation bands are seen very strongly at $1242 and $742 cm À1 in our spectra, as found also by Rey et al [163,164]. The bands at 500-750 cm À1 discussed in relation with Fig.…”

Section: Other Systemssupporting

confidence: 91%

“…A pronounced delocalization of the negative charge on the nitrogen and oxygen atoms was found, and a marked double-bond character of the S-N-S moiety for the anion [163,164]. A tentative assignment of some characteristic vibrations of the [Tf 2 N]…”

Section: Other Systemsmentioning

confidence: 92%

“…In addition to these studies, the structure of the bis(trifluoromethylsulfonyl)imide ([Tf 2 N] À ) anion in the liquid state has been investigated by means of IR and Raman spectroscopy and ab-initio self-consistent Hartree-Fock and DFT calculations on the free ion, aiming at a determination of the equilibrium geometry and understanding of the vibrational spectrum [137,[163][164][165]. A pronounced delocalization of the negative charge on the nitrogen and oxygen atoms was found, and a marked double-bond character of the S-N-S moiety for the anion [163,164].…”

Section: Other Systemsmentioning

confidence: 99%

“…À anion was performed using the spectra of aqueous solutions for comparison in order to analyze the conformational isomerism and ion-pairing effects [163,164].…”

Section: Other Systemsmentioning

confidence: 99%

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Raman Spectroscopy and Ab-Initio Model Calculations on Ionic Liquids

2007

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Summary.A review of the recent developments in the study and understanding of room temperature ionic liquids are given. An intimate picture of how and why these liquids are not crystals at ambient conditions is attempted, based on evidence from crystallographical results combined with vibrational spectroscopy and ab-initio molecular orbital calculations. A discussion is given, based mainly on some recent FT-Raman spectroscopic results on the model ionic liquid system of 1-butyl-3-methylimidazolium ([C 4 mim][X]) salts. The rotational isomerism of the [C 4 mim] þ cation is described: the presence of anti and gauche conformers that has been elucidated in remarkable papers by Hamaguchi et al. Such presence of a conformational equilibrium seems to be a general feature of the room temperature liquids. Then the ''localized structure features'' that apparently exist in ionic liquids are described. It is hoped that the structural resolving power of Raman spectroscopy will be appreciated by the reader. It is of remarkable use on crystals of known different conformations and on the corresponding liquids, especially in combination with modern quantum mechanics calculations. It is hoped that these interdisciplinary methods will be applied to many more systems in the future. A few examples will be discussed.

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Section: Other Systemssupporting

confidence: 91%

Section: Other Systemsmentioning

confidence: 92%

Section: Other Systemsmentioning

confidence: 99%

“…À anion was performed using the spectra of aqueous solutions for comparison in order to analyze the conformational isomerism and ion-pairing effects [163,164].…”

Section: Other Systemsmentioning

confidence: 99%

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Raman Spectroscopy and Ab-Initio Model Calculations on Ionic Liquids

2007

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“…S2). Although overlap of the signals from PFPE 1000 -DMC and LiTFSI precludes the observation of LiTFSI peak shifts in this region as the salt is being solvated, the decreased intensities at 1,350 cm −1 in PFPE 1000 -DMC/LiTFSI blends is consistent with the presence of dissociated Li + and TFSI − ions (25)(26)(27).…”

Section: Significancementioning

confidence: 87%

Nonflammable perfluoropolyether-based electrolytes for lithium batteries

Wong

Thelen

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

204

214

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The flammability of conventional alkyl carbonate electrolytes hinders the integration of large-scale lithium-ion batteries in transportation and grid storage applications. In this study, we have prepared a unique nonflammable electrolyte composed of low molecular weight perfluoropolyethers and bis(trifluoromethane)sulfonimide lithium salt. These electrolytes exhibit thermal stability beyond 200°C and a remarkably high transference number of at least 0.91 (more than double that of conventional electrolytes). Li/LiNi 1/3 Co 1/3 Mn 1/3 O 2 cells made with this electrolyte show good performance in galvanostatic cycling, confirming their potential as rechargeable lithium batteries with enhanced safety and longevity.fluorinated polymers | nonflammable electrolytes L arge-scale rechargeable batteries are expected to play a key role in today's emerging sustainable energy landscape (1, 2). State-of-the-art lithium (Li) batteries not only are used to power zero-emission electric vehicles, but they currently are gaining traction as backup power in aircraft and smart grid applications (3, 4). The electrolyte used in these batteries, however, hinders their use in large-scale applications: it contains a flammable mixture of alkyl carbonate solvents that frequently leads to safety issues. Dimethyl carbonate (DMC), an important component in commercial Li-ion battery electrolytes, has an HMIS (Hazardous Materials Identification System) flammability rating of 3 on a scale of 0-4, indicating a high risk of ignition under most operating conditions. The intrinsic instability of carbonate-based solvents worsens at higher temperatures, at which exothermic electrolyte breakdown often leads to thermal runaway (5, 6), resulting in catastrophic failure of the battery. Although this failure rate stands at about one in ten million systems, it is intolerable for large-scale applications in which cost and user safety might be heavily compromised. This necessitates the development of radically new electrolytes with improved safety.Desirable electrolyte properties include a large window of phase stability (no vaporization or crystallization), complete nonflammability, a wide electrochemical stability window, and suitable ionic transport for the targeted application. There are many approaches to synthesizing materials with these properties, e.g., ionic liquids (7, 8), gel-polymer matrices (9, 10), and small molecule additives (11-13). Systems using poly(ethylene oxide) (PEO) also are well studied (14,15). PEO can solvate high concentrations of lithium salts and is considered nonflammable. Unfortunately, practical conductivity often is limited within a high temperature range (14), and it is well known that in these systems, the motion of the Li ion carries only a small fraction of the overall current (also known as the Li-ion transference number, t + ). PEO-based electrolytes typically exhibit t + values between 0.1 and 0.5 (16-20), leading to strong salt concentration gradients across the electrolytes that limit power density. Recently, we repor...

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