Phase behaviour, transport properties, and interactions in Li-salt doped ionic liquids

Pitawala, Jagath; Kim, Jae Kwang; Jacobsson, Per; Koch, V. R.; Croce, F.; Matic, Aleksandar

doi:10.1039/c1fd00056j

Cited by 83 publications

(96 citation statements)

References 25 publications

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“…Raman spectra were further collected around the ≈745 cm −1 region, where this band is an indicator of the Li + coordination state with TFSI − anion ( Figure ). [ 27 ] The Raman peak at around 745 cm −1 could be deconvoluted into two components: the high shift of 748 cm −1 is associated to Li + coordinated by TFSI − anions while the low shift of 742 cm −1 can be assigned as free TFSI − anions not interacting with the Li + cations. While ILE shows a free TFSI − anion intensity of only 76%, IL GPE displays 85% of Li + ‐uncoordinated anions due to the interaction between the anions and the fluorinated polymer chains.…”

Section: Resultsmentioning

confidence: 99%

Amine‐Functionalized Boron Nitride Nanosheets: A New Functional Additive for Robust, Flexible Ion Gel Electrolyte with High Lithium‐Ion Transference Number

Kim

Liu

et al. 2020

Adv Funct Materials

113

108

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Ion gel electrolytes show great potential in solid-state batteries attributed to their outstanding characteristics. However, because of the strong ionic nature of ionic liquids, ion gel electrolytes generally exhibit low lithium-ion transference number, limiting its practical application. Aminefunctionalized boron nitride (BN) nanosheets (AFBNNSs) are used as an additive into ion gel electrolytes for improving their ion transport properties. The AFBNNSs-ion gel shows much improved mechanical strength and thermal stability. The lithium-ion transference number is increased from 0.12 to 0.23 due to AFBNNS addition. More importantly, for the first time, nuclear magnetic resonance analysis reveals that the amine groups on the BN nanosheets have strong interaction with the bis(trifluoromethanesulfonyl)imide anions, which significantly reduces the anion mobility and consequently increases lithium-ion mobility. Battery cells using the optimized AFBNNSs-ion gel electrolyte exhibit stable lithium deposition and excellent electrochemical performance. A LiFePO 4 |Li cell retains 92.2% of its initial specific capacity after the 60th cycle while the cell without AFBNNSs-gel electrolyte only retains 53.5%. The results not only demonstrate a new strategy to improve lithium-ion transference number in ionic liquid electrolytes, but also open up a potential avenue to achieve solid-state lithium metal batteries with improved performance. and high safety levels. Lithium metal batteries (LMBs), owing to the low redox potential (−3.04 V vs standard hydrogen electrode) and ultrahigh theoretical capacity (3860 mAh g −1 ) of the lithium (Li) metal anode, are promising to fulfill these requirements. [1] However, the organic liquid electrolyte (LE), currently widely used in the LMBs, makes LMBs face severe safety concerns such as electrolyte leakage and combustion due to the intrinsic fluidity, flammability, and electrochemical instability. Replacing the organic liquid electrolyte with solid-state electrolytes (SSEs) has been proven to be an efficient way to overcome these problems. [2] Because of their high mechanical stability and structural integrity, SSEs enable facile cell fabrication and prevent electrolyte leakage, offering greater safety than liquid electrolytes. Current solid-state electrolytes include solid polymer electrolytes (SPEs) and inorganic electrolytes (IEs). Unfortunately, SPEs suffer from a poor ionic conductivity at room temperature, while the IEs show innate brittleness and intrinsically narrow electrochemical stability along with high contact resistance. Compared to SPEs and IEs, gel electrolytes, which are prepared by entrapping liquid electrolytes into a solid matrix, provide exceptional properties such as high ionic conductivity, low interfacial resistance, good mechanical strength, and flexibility.Liquid mediums are one of the key components in gel electrolytes. Among the candidates, ionic liquids (ILs), also known as room temperature molten salts, can result in high performance gel electrolytes because of the...

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Section: Resultsmentioning

confidence: 99%

Amine‐Functionalized Boron Nitride Nanosheets: A New Functional Additive for Robust, Flexible Ion Gel Electrolyte with High Lithium‐Ion Transference Number

Kim

Liu

et al. 2020

Adv Funct Materials

113

108

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“…From the peak fit analysis, the average coordination number (N) is obtained. The average coordination/solvation number of the ligands surrounding Al 3 þ is calculated according to the following equation [49,50].…”

Section: Resultsmentioning

confidence: 99%

Electrodeposition of Al from a 1-butylpyrrolidine-AlCl3 ionic liquid

Pulletikurthi

Bödecker

Borodin

et al. 2015

Progress in Natural Science: Materials International

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The addition of 1-butylpyrrolidine to AlCl 3 results in the formation of an electrolyte that is suited to Al deposition. The feasibility of electrodepositing Al from the synthesized electrolyte was investigated. Several compositions of AlCl 3 and 1-butylpyrrolidine were prepared for this purpose. These mixtures show a different phase behavior at various compositions of AlCl 3 and 1-butylpyrrolidine. IR, Raman and NMR spectroscopy were employed to characterize the synthesized liquids. Among the prepared compositions, 1:1.2 mol ratio of 1-butylpyrrolidine: AlCl 3 and the upper phase of 1:1.3 mol ratio of 1-butylpyrrolidine:AlCl 3 were found to be suitable for Al electrodeposition at room temperature (RT). Uniform and thick ( $mm thick) layers of Al were obtained on copper at RT. Al deposition occured from the cationic species of AlCl 3 À x L þ y (where x r2, y ¼ 1-2, and L¼1-butylpyrrolidine) in this electrolyte. This behavior is contrary to the well investigated classic AlCl 3 based ionic liquids, where the deposition of Al occurs mainly from anionic Al 2 Cl À 7 ions.

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“…The conductivity of Pyr 12O1 TFSI is higher than that of Pyr 14 TFSI due to the smaller size of Pyr 12O1 + cation as compared to Pyr 14 + which results in a higher Pyr 12O1 + mobility. 33 In the Mg 2+ -IL electrolytes, this is not the case ( Figure S6), which suggests that other phenomena are also occurring. [30][31][32] The parameters determined from fitting the data to the VTF equation are shown in Table S1 and S2.…”

Section: Molecular Organizationmentioning

confidence: 92%

Mechanisms of Magnesium Ion Transport in Pyrrolidinium Bis(trifluoromethanesulfonyl)imide-Based Ionic Liquid Electrolytes

Jeremias¹,

Giffin

Moretti

et al. 2014

J. Phys. Chem. C

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Inert polar aprotic electrolytes based on pyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquids were investigated for Mg battery applications. On a molecular-scale, there are two TFSIpopulations coordinating Mg 2+ ions: one in a bidentate coordination to a single Mg 2+ and one in a bridging geometry between two Mg 2+ ions. On average each Mg 2+ cation is surrounded by 3 -4 TFSIanions. The electrolytes, in general, remain amorphous far below ambient conditions, which results to a wide useable temperature range in practical devices. There is a change in the ratio of bidentate:bridging TFSIand in the conductivity, viscosity and diffusion behavior at a salt mole fraction of 0.12 -0.16. At concentrations above this threshold, there is a more dramatic decrease of the diffusion coefficients and the conductivity with increasing salt concentration due to slower exchange of the more strongly coordinated bidentate TFSI -. The mechanism of ion transport likely proceeds via structural diffusion is exchange of the bridging and "free" TFSIanions within adjacent [Mg n (TFSI) m ] (m-2n)clusters and exchange of bidentate anions via a bidentate to bridging mechanism. The vehicular mechanism likely makes only a small contribution. At concentrations above approximately 0.16 mole fraction, the structural diffusion is more closely related to the tightly bound bidentate anions. Mg(TFSI) 2 ] 0.32 electrolytes was determined by an automated conductimeter equipped with a frequency analyzer and a thermostatic bath (MMates Italia). The ILs were housed in sealed, glass conductivity cells (mounted in a dry room, dew point <-50°C) equipped

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Phase behaviour, transport properties, and interactions in Li-salt doped ionic liquids

Cited by 83 publications

References 25 publications

Amine‐Functionalized Boron Nitride Nanosheets: A New Functional Additive for Robust, Flexible Ion Gel Electrolyte with High Lithium‐Ion Transference Number

Amine‐Functionalized Boron Nitride Nanosheets: A New Functional Additive for Robust, Flexible Ion Gel Electrolyte with High Lithium‐Ion Transference Number

Electrodeposition of Al from a 1-butylpyrrolidine-AlCl3 ionic liquid

Mechanisms of Magnesium Ion Transport in Pyrrolidinium Bis(trifluoromethanesulfonyl)imide-Based Ionic Liquid Electrolytes

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