Lithium bis(fluorosulfonyl)imide (LiFSI) as conducting salt for nonaqueous liquid electrolytes for lithium-ion batteries: Physicochemical and electrochemical properties

Han, Hongjing; Zhou, Sisi; Zhang, Daijun; Feng, Shouhua; Li, Lifei; Li, Kai; Feng, Wenfang; Nie, Jun; Li, Hong; Huang, Xuejie; Armand, Michel; Zhou, Zhibin

doi:10.1016/j.jpowsour.2010.12.040

Cited by 441 publications

(330 citation statements)

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“…This is possibly an advantage, since the properties of the anions at the electrode or current collector/ electrolyte interface is dependent on the type of functional group. 2,12,25 Hence, if necessary, hybrid lithium salts may offer a possibility to fine-tune the properties of electrode and/or aluminum current collector passivation films, without too much of a compromise in the anion stability or the lithium salt dissociation. Finally, in agreement with the phosphoryl imide CPI (P3), the most promising sulfonyl imide is the symmetrically cyano-substituted CSI (S3).…”

Section: Imide Substitution Effectsmentioning

confidence: 99%

“…10 For LiFSI there has, in addition to poor aluminum compatibility, been concerns about the thermal stability of the salt, 11 but a recent study suggests that these problems can be resolved by using a salt of high purity. 12 As a component of ILs, FSI offers highly ion conductive, low viscous electrolytes, with the important ability to passivate both a graphite 13 and a lithium metal anode. The latter anions can be considered quasi-spherical and rigid, while the imides are quasi-linear and flexible.…”

Section: Introductionmentioning

confidence: 99%

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Novel Lithium Imides; Effects of -F, -CF3, and -C≡N Substituents on Lithium Battery Salt Stability and Dissociation

et al. 2012

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New lithium imide salts have been studied using computational chemistry methods. Intrinsic anion oxidation potentials and ion pair dissociation energies are presented for six lithium sulfonyl imides (R-O 2 S-N-SO 2 -R) and six lithium phosphoryl imides (R 2 -OP-N-PO-R 2 ), as a function of -F, -CF 3 , and -C7N substitution. The modelled properties are used to estimate the electrochemical oxidation stability of the anions and the relative ease of charge carrier creation in lithium battery electrolytes. The results show that both properties are improved with cyanosubstitution, which in part is corroborated when comparing with other classes of lithium salts. However, the comparison also shows ambiguous oxidation stability results for cyano-substituted reference salts of the type PF x (CN) 6−x − and BF x (CN) 4−x − , using two different approaches -we present a tentative explanation for this. For the imide anions and PF 6 − , the bond dissociation energy is introduced as a third property, to gauge the thermal stability of the imide anions. The results suggest that the C-S and C-P bonds are the most liable to break and that the thermal stability is inversely related to the ion pair dissociation energy.

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Section: Imide Substitution Effectsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Novel Lithium Imides; Effects of -F, -CF3, and -C≡N Substituents on Lithium Battery Salt Stability and Dissociation

et al. 2012

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“…Recent papers, however, indicate that battery electrolytes with LiFSI have very promising properties-i.e., a relatively high thermal and hydrolytic stability (relative to LiPF 6 ), a high conductivity (comparable to electrolytes with LiPF 6 ) and a wide liquidus range. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] One key concern originated from reports which indicated that the use of the LiFSI salt in electrolytes results in severe corrosion of the battery Al current collector at high potentials. 3,15 It has recently been demonstrated, however, that this was likely due to chloride impurities in the salt (from the synthesis procedures) rather than the LiFSI salt itself.…”

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confidence: 99%

Electrolyte Solvation and Ionic Association

Han

Borodin

Seo

et al. 2014

J. Electrochem. Soc.

116

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Electrolytes with the salt lithium bis(fluorosulfonyl)imide (LiFSI) have been evaluated relative to comparable electrolytes with other lithium salts. Acetonitrile (AN) has been used as a model electrolyte solvent due to the simplicity of its solvation interactions (the AN molecule has only a single electron lone-pair for Li + cation coordination). The information obtained from the thermal phase behavior, solvation/ionic association interactions, quantum chemical (QC) calculations and molecular dynamics (MD) simulations (with an APPLE&P many-body polarizable force field for the LiFSI salt) of the (AN) n -LiFSI mixtures provides detailed insight into the coordination interactions of the FSI − anions and the wide variability noted in the electrolyte transport properties (i.e., viscosity and ionic conductivity). was first reported in a patent application in 1995 which indicated a method for its synthesis.1 Its use in research studies, however, has been restricted until quite recently due to the limited availability and high cost of this salt. A limited number of publications have been reported about the use of the FSI − anion for electrolytes in recent years, 2-55 but many of these have focused on FSI − -based ionic liquids instead of the LiFSI salt. Recent papers, however, indicate that battery electrolytes with LiFSI have very promising properties-i.e., a relatively high thermal and hydrolytic stability (relative to LiPF 6 ), a high conductivity (comparable to electrolytes with LiPF 6 ) and a wide liquidus range. 2-18One key concern originated from reports which indicated that the use of the LiFSI salt in electrolytes results in severe corrosion of the battery Al current collector at high potentials. 3,15 It has recently been demonstrated, however, that this was likely due to chloride impurities in the salt (from the synthesis procedures) rather than the LiFSI salt itself. 12To fully capitalize upon the use of LiFSI as an alternative lithium salt for advanced lithium batteries, it is necessary to understand the behavior of this salt in bulk electrolyte solutions. The preceding work in this series of publications has scrutinized the relationship between the solution structure and transport properties of electrolytes in detail. 56-59The present study extends this focus to acetonitrile-based (AN) n -LiFSI electrolytes to better understand the characteristics of this relatively * Electrochemical Society Student Member.* * Electrochemical Society Active Member. z E-mail: Wesley.Henderson@pnnl.gov; oleg.a.borodin.civ@mail.mil new electrolyte salt. Of particular interest are the recent reports which noted that highly concentrated (AN) n -LiTFSI and -FSI electrolytes have a high electrochemical stability to reduction at negative potentials (in sharp contrast to more dilute solutions with nitrile solvents) which allows for the rapid and reversible charging/discharging of graphitic electrodes. 5,60 ExperimentalMaterials.-Anhydrous AN (Sigma-Aldrich, 99.8%) and LiFSI (Suzhou Fluolyte Co., Ltd., >99.5%) were used as-received....

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“…1, 2,6,7 Recent studies [8][9][10] have shown that lithium bis(fluorosulfonyl)imide (LiFSI) can be thermally stable up to 200…”

mentioning

confidence: 99%

Effect of Mixtures of Lithium Hexafluorophosphate (LiPF₆) and Lithium Bis(fluorosulfonyl)imide (LiFSI) as Salts in Li[Ni_1/3Mn_1/3Co_1/3]O₂/Graphite Pouch Cells

Wang

Xiao²,

Wells³

et al. 2014

J. Electrochem. Soc.

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The effect of mixtures of lithium hexafluorophosphate (LiPF 6 ) and lithium bis(fluorosulfonyl)imide (LiFSI) with different molar ratios in the electrolyte of Li[Ni 1/3 Mn 1/3 Co 1/3 ]O 2 /graphite pouch cells was studied using the ultra-high precision charger (UHPC) at Dalhousie University, an automated storage system, electrochemical impedance spectroscopy (EIS) and gas evolution measurements. Ethylene carbonate: ethyl methyl carbonate (EC:EMC, 3:7 wt.% ratio) solvent was used as the base solvent in these studies. Li[Ni 1/3 Mn 1/3 Co 1/3 ]O 2 /graphite pouch cells containing both LiPF 6 and LiFSI (with a total salt content of 1 M) with or without 2% VC showed smaller or similar self-discharge, lower charge transfer resistance (R ct ), and smaller amounts of gas evolution during formation and during storage at high temperature, compared to cells containing only 1 M LiPF 6 with and without 2% VC, respectively. For cells without 2% VC, cells with 0.3 M LiPF 6 + 0.7 M LiFSI showed the smallest self-discharge and the lowest R ct after 40 • C storage. For cells with 2% VC, cells with 0.5 M LiPF 6 + 0.5 M LiFSI + 2% VC showed the lowest voltage drop and the lowest R ct after 40 • C storage. The UPHC cycling data showed that cells containing LiPF 6 :LiFSI mixtures with 2% VC showed similar coulombic efficiency (CE), and similar charge end-point capacity slippage compared to cells with 1 M LiPF 6 + 2% VC. The combination of LiFSI and LiPF 6 in electrolytes that contain 2% VC can bring benefits of improved storage properties and reduced gas evolution at high temperature while maintaining all other properties of the cells in experiments limited to 4.2 V. However, preliminary experiments at voltages up to 4.45 V suggest that LiFSI may lead to increased transition metal dissolution (Ni, Mn and Co) compared to lithium bistrifluoromethane sulfonyl imide (LiTSFI), another salt additive used to improve storage properties and reduce gassing. The use of electrolyte additives is one of the most economical and effective ways to improve the performance of Li-ion cells.1,2 Vinylene carbonate (VC) has been shown to be an effective electrolyte additive for the improvement of cell performance.3,4 Burns et al. 5 showed that LiCoO 2 /graphite cells with 2% VC demonstrated improved life-time with a higher coulombic efficiency (CE) and lower charge and discharge end-point capacity slippage rates, compared to cells without VC. Lithium hexafluorophosphate (LiPF 6 ) is the most commonly used salt in Li-ion cells, due to balance of properties, such as high dissociation constant, high conductivity and good electrochemical stability against Al corrosion.1,2,6,7Recent studies [8][9][10] have shown that lithium bis(fluorosulfonyl)imide (LiFSI) can be thermally stable up to 200• C. However, Al current collector corrosion was observed in Li-ion cells with LiFSI-based electrolytes.10-14 The Al corrosion problem for LiFSI-based electrolytes can be readily solved by the addition of LiPF 6 , which can be decomposed to form a protective film of AlF 3 . ...

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Lithium bis(fluorosulfonyl)imide (LiFSI) as conducting salt for nonaqueous liquid electrolytes for lithium-ion batteries: Physicochemical and electrochemical properties

Cited by 441 publications

References 37 publications

Novel Lithium Imides; Effects of -F, -CF3, and -C≡N Substituents on Lithium Battery Salt Stability and Dissociation

Novel Lithium Imides; Effects of -F, -CF3, and -C≡N Substituents on Lithium Battery Salt Stability and Dissociation

Electrolyte Solvation and Ionic Association

Effect of Mixtures of Lithium Hexafluorophosphate (LiPF₆) and Lithium Bis(fluorosulfonyl)imide (LiFSI) as Salts in Li[Ni_1/3Mn_1/3Co_1/3]O₂/Graphite Pouch Cells

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Lithium bis(fluorosulfonyl)imide (LiFSI) as conducting salt for nonaqueous liquid electrolytes for lithium-ion batteries: Physicochemical and electrochemical properties

Cited by 441 publications

References 37 publications

Novel Lithium Imides; Effects of -F, -CF3, and -C≡N Substituents on Lithium Battery Salt Stability and Dissociation

Novel Lithium Imides; Effects of -F, -CF3, and -C≡N Substituents on Lithium Battery Salt Stability and Dissociation

Electrolyte Solvation and Ionic Association

Effect of Mixtures of Lithium Hexafluorophosphate (LiPF6) and Lithium Bis(fluorosulfonyl)imide (LiFSI) as Salts in Li[Ni1/3Mn1/3Co1/3]O2/Graphite Pouch Cells

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Effect of Mixtures of Lithium Hexafluorophosphate (LiPF₆) and Lithium Bis(fluorosulfonyl)imide (LiFSI) as Salts in Li[Ni_1/3Mn_1/3Co_1/3]O₂/Graphite Pouch Cells