Pyrrolidinium Ionic Liquid Electrolyte with Bis(trifluoromethylsulfonyl)imide and Bis(fluorosulfonyl)imide Anions: Lithium Solvation and Mobility, and Performance in Lithium Metal–Lithium Iron Phosphate Batteries (original) (raw)
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LiTFSI-BEPyTFSI as an improved ionic liquid electrolyte for rechargeable lithium batteries
2007
We report an electrochemical study of solutions of lithium bis(trifluoromethanesulfonyl)imide, LiTFSI, in a N-n-butyl-N-ethylpyrrolidinium bis(trifluoromethanesulfonyl)imide, BEPyTFSI. We show that these ionic liquid solutions have stability towards lithium metal electrode which allows various electrochemical tests, including impedance spectroscopy and voltammetry. The ionic conductivity and lithium transference number, of the order of 10 −3 S cm −1 and 0.4, respectively, make these solutions suitable for application as electrolytes in advanced lithium batteries. A prototype of these batteries, having lithium iron phosphate as the cathode, showed good performance in terms of charge-discharge efficiency and rate capability. The results reported in this work, although preliminary, are encouraging in supporting the practical interest of this LiTFSI-BEPyTFSI class of lithium conducting ionic liquids.
Pure and Applied Chemistry, 2019
In this work, the physical, transport and electrochemical properties of various electrolytic solutions containing the 1-propyl-1-methylpyrrolidinium bis[fluorosulfonyl]imide ([C3C1pyr][FSI]) mixed with the lithium bis[(trifluoromethyl)sulfonyl]imide (Li[TFSI]) over a wide range of compositions are reported as a function of temperature at atmospheric pressure. First, the ionicity, lithium transference number, and transport properties (viscosity and conductivity) as well as the volumetric properties (density and molar volume) were determined as a function of lithium salt concentration from 293 to 343 K. Second, the self-diffusion coefficient of each ion in solution was measured by nuclear magnetic resonance (NMR) spectroscopy with pulsed field gradients (PFG). Moreover, an analysis of the collected nuclear Overhauser effect (NOE) data along with ab initio and COSMO-RS calculations was conducted to depict intra and intermolecular neighbouring within the electrolytic mixtures. Based on ...
Pyrrolidinium Containing Ionic Liquid Electrolytes for Li-Based Batteries
Molecules
Ionic liquids are potential alternative electrolytes to the more conventional solid-state options under investigation for future energy storage solutions. This review addresses the utilization of IL electrolytes in energy storage devices, particularly pyrrolidinium-based ILs. These ILs offer favorable properties, such as high ionic conductivity and the potential for high power drain, low volatility and wide electrochemical stability windows (ESW). The cation/anion combination utilized significantly influences their physical and electrochemical properties, therefore a thorough discussion of different combinations is outlined. Compatibility with a wide array of cathode and anode materials such as LFP, V2O5, Ge and Sn is exhibited, whereby thin-films and nanostructured materials are investigated for micro energy applications. Polymer gel electrolytes suitable for layer-by-layer fabrication are discussed for the various pyrrolidinium cations, and their compatibility with electrode mater...
Solid State Ionics A multiple electrolyte concept for lithium-metal batteries
A cross-linked polymer membrane formed by poly(ethylene oxide) (PEO), N-methoxyethyl-N-methylpyrrolidium (fluorosulfonyl)(trifluoromethanesulfonyl)imide (Pyr 12O1 FTFSI) ionic liquid and LiFTFSI salt is proposed as the electrolyte for lithium-metal batteries. The ternary membrane has a PEO:Pyr 12O1 FTFSI:LiFTFSI composition of 20:6:4 by mole, which ensures thermal stability up to 220 °C, overall ionic conductivity of 10 − 3 S cm − 1 at 40 °C and suitable Li + transport properties. Combined with the LiFePO 4 composite electrode, whose pores are filled with the Pyr 12O1 FTFSI:LiFTFSI electrolyte, and Li-metal anode, it yields Li/LiFePO 4 cells delivering at 40 °C stable capacity (150 mAh g − 1 or 0.7 mAh cm − 2) with coulombic efficiency higher than 99.5%. Impedance spectroscopy measurements reveal low resistance of the electrode/electrolyte interface at both the anode and the cathode. Preliminary results at 20 °C indicates a capacity of 130 mAh g − 1 at C/10 rate (17 mA g − 1) with coulombic efficiency higher than 99.5%, thereby suggesting PEO:Pyr 12O1 FTFSI:LiFTFSI as suitable electrolyte for lithium-metal polymer batteries for stationary storage applications, coupled for example with PV and wind generation.
Electrochimica Acta, 2010
Several 1-alkyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide ionic liquids (alkyl-DMimTFSI) were prepared by changing carbon chain lengths and configuration of the alkyl group, and their electrochemical properties and compatibility with Li/LiFePO 4 battery electrodes were investigated in detail. Experiments indicated the type of ionic liquid has a wide electrochemical window (−0.16 to 5.2 V vs. Li + /Li) and are theoretically feasible as an electrolyte for batteries with metallic lithium as anode. Addition of vinylene carbonate (VC) improves the compatibility of alkyl-DMimTFSI-based electrolytes towards lithium anode and LiFePO 4 cathode, and enhanced the formation of solid electrolyte interface to protect lithium anodes from corrosion. The electrochemical properties of the ionic liquids obviously depend on carbon chain length and configuration of the alkyl, including ionic conductivity, viscosity, and charge/discharge capacity etc. Among five alkyl-DMimTFSI-LiTFSI-VC electrolytes, Li/LiFePO 4 battery with the electrolyte-based on amyl-DMimTFSI shows best charge/discharge capacity and reversibility due to relatively high conductivity and low viscosity, its initial discharge capacity is about 152.6 mAh g −1 , which the value is near to theoretical specific capacity (170 mAh g −1 ). Although the battery with electrolyte-based isooctyl-DMimTFSI has lowest initial discharge capacity (8.1 mAh g −1 ) due to relatively poor conductivity and high viscosity, the value will be dramatically added to 129.6 mAh g −1 when 10% propylene carbonate was introduced into the ternary electrolyte as diluent. These results clearly indicates this type of ionic liquids have fine application prospect for lithium batteries as highly safety electrolytes in the future.
Ionic Liquid Electrolytes for Safer Lithium Batteries
Journal of The Electrochemical Society
In this paper we report on the investigation of ionic liquid-based electrolytes with enhanced characteristics. In particular, we have studied ternary mixtures based on the lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt and two ionic liquids sharing the same cation (N-methyl-N-propyl pyrrolidinium, PYR 13), but different anions, bis(trifluoromethanesulfonyl)imide (TFSI) and bis(fluorosulfonyl)imide (FSI). The LiTFSI-PYR 13 TFSI-PYR 13 FSI mixtures, found to be ionically dissociated, exhibit better ion transport properties (about 10 −3 S cm −1 at −20 • C) with respect to similar ionic liquid electrolytes till reported in literature. An electrochemical stability window of 5 V is observed in carbon working electrodes. Preliminary battery tests confirm the good performance of these ternary electrolytes with high-voltage NMC cathodes and graphite anodes. Ionic liquid electrolyte mixtures, PYR 13 TFSI, PYR 13 FSI.
Journal of Power Sources, 2014
Enhanced performance of ILs based on fluorosulfonyl-(trifluoromethanesulfonyl) imide (FTFSI). PYR 12O1 FTFSI-LiFTFSI offers excellent electrochemical performance at room temperature. Remarkable performance of LTO/PYR 12O1 FTFSI-LiFTFSI/LFP cells at room temperature. High stability of LTO/PYR 12O1 FTFSI-LiFTFSI/LFP cells at elevated temperature. Keywords: Lithium ion battery Ionic liquids N-Methoxyethyl-N-methylpyrrolidinium fluorosulfonyl-(trifluoromethanesulfonyl) imide LiFePO 4 Li 4 Ti 5 O 12 Electrochemical performance a b s t r a c t