New Thiourea-Based Ionic Liquid as an Electrolyte Additive to Improve Cell Safety and Enhance Electrochemical Performance in Lithium-Ion Batteries (original) (raw)
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Scientific Reports
A novel dicationic room temperature ionic liquid, 1,1′-(5,14-dioxo-4,6,13,15-tetraazaoctadecane-1,18-diyl) bis(3-(sec-butyl)-1H-imidazol-3-ium) bis((trifluoromethyl)-sulfonyl) imide has been synthesized and fully characterized. Its thermal and electrochemical analyses along with transport properties have been studied. We propose it as a potential nominal additive to the commonly used conventional organic carbonate electrolyte mixture and study its adaptability in Lithium-ion batteries which are the prime power sources for ultraportable electronic devices. We have compared the performance characteristics of the full cells made without and with this ionic liquid. The cells comprise lithium nickel cobalt manganese oxide cathode, graphite anode and ethylene carbonate - dimethyl carbonate (1:1, v/v + LiPF6) mixture electrolyte with nominal amount of ionic liquid as additive. The major concern with conventional electrolytes such as degradation of the materials inside batteries has been ad...
Ethoxy-Ester Functionalized Imidazolium based Ionic Liquids for Lithium Ion Batteries
ChemistrySelect, 2018
Ethoxy ester functionalized imidazolium and bis(tri fluoromethanesulfonyl)imide based ionic liquids (ILs) are synthesized and considered as electrolyte for lithium ion batteries. The series of ethoxy ester functionalized ionic liquids were chosen with increase in ethoxy unit from one to three, followed by polymeric units. These ionic liquids provide both ester and ethoxy groups as interaction sites for Li + ions enhancing the Li + ion transportation, resulting in ionic conductivity of 10 À 3 Scm À1 at 25 8C, which is of 10 3 factor higher than ethoxy containing polyethylene oxide solid polymer electrolyte. It's noteworthy that the conductivity increases as ethoxy units are increased from one to three units, followed by a decrease for the polymeric ethoxy unit. Electrochemical stability window of these ionic liquids improves as the ethoxy groups are added to imidazolium cation. The Li/LiFePO 4 cell fabricated with [ME 3 AMIm][TFSI] electrolyte shows good initial discharge capacity of 98.5 mAhg À1 at 0.05 Crate at room temperature, which gradually decreases with cycling. Systematic investigation of electrode surfaces by using SEM and EDX shows deposition of passivation layers on their surfaces. Ionic liquids fabricated by this facile method provide a promising model system for understanding the molecular interactions in promoting the lithium-ion conduction mechanism. The advantages and the limits associated to series of ionic liquid electrolytes are critically investigated.
Journal of The Electrochemical Society, 2012
This manuscript reports the development of a safe and green lithium-ion battery using lithium iron phosphate (LiFePO 4) as a positive electrode, graphite (Cgr) as a negative electrode, and an Ionic Liquid (IL) electrolyte solution based on 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)-imide (C 1 C 6 ImNTf 2). Vinylene carbonate (VC) was tested as an electrolyte additive. The electrochemical stability of (C 1 C 6 ImNTf 2) and their binary mixture referred as (Li)(C 1 C 6 ImNTf 2) were investigated. In addition the electrochemical behavior of the graphite electrode was studied through cyclic voltammetry experiments in the presence and absence of VC co-additive. Complementary cycling tests demonstrated the benefic effect of VC on the charge-discharge performances for the full Lithium ion configuration based on Cgr/LiFePO 4 .
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.
Energy Materials, 2023
The commercial lithium-ion batteries (LIBs) rely on lithium hexafluorophosphate (LiPF6), which is extremely sensitive to moisture and liable to thermal decomposition. Lithium bis (trifluoro methane sulfonyl) imide (LiTFSI), as a promising electrolyte salt, possesses high thermal stability and excellent moisture tolerance. However, LiTFSI is closely related to severe corrosion of the aluminum (Al) current collector at high voltage. Herein, phosphonate-functionalized imidazolium ionic liquid (PFIL) is developed and utilized as an electrolyte co-solvent to inhibit the oxidative dissolution of the Al current collector. PFIL can suppress Al corrosion by participating in the interface reaction and forming a stable and reliable protective film on the surface of Al foils, as confirmed by X-ray photoelectron spectroscopy. Thanks to the corrosion suppression of the Al current collector, the Li||LiNi0.8Mn0.1Co0.1O2 (NCM811) cells with PFIL-containing electrolytes exhibit better cycling performance and improved capacity retention. This work proposes an effective strategy for the advancement of high-voltage LIBs and contributes to promoting the widespread use of the sulfone imide-based lithium salts.
Alkoxy substituted imidazolium-based ionic liquids as electrolytes for lithium batteries
The design and the optimization of new electrochemically stable and safer electrolytes for both Li-ion and Li-air/Li-O2 batteries is a key-target in the field of clean energy. Ionic liquids (ILs) were often indicated as components of the electrolytes of the future, because they could fulfil all the requirements for the use in electronic devices and they also address the safety issues for large-scale applications. In this work, two ether-functionalized ILs, namely 1-(2-methoxyethyl)-3-methylimidazolium TFSI (IMI1,2O1TFSI) and 3-(2-(2-methoxyethoxy)ethyl)-1-methylimidazolium TFSI (IMI1,1O2O1TFSI) were synthesized and characterized from a physical and electrochemical point of view. The thermal features, viscosity, conductivity and electrochemical stability were compared with those of an alkyl-IMITFSI (BuMeIMITFSI) in order to evaluate the influence of the alkoxy-groups on the electrolyte performances. Preliminary battery tests in Li/LiFePO4 cells containing solutions of IL-LiTFSI mixed with EC/DEC as electrolytes were also performed to address the cycling behaviour and the delivered capacity. D e p t . o f C h e m i s t r y -S e c t i o n o f P h ys i c a l C h e m i s t r y U N I V E R S I T Y OF P AV I A VIALE TARAMELLI, Reference: Submission of the article Alkoxy substituted imidazolium-based ionic liquids as electrolytes for lithium batteries, by S. Ferrari et al. Dear Editor, herein attached please find the paper Alkoxy substituted imidazolium-based ionic liquids as electrolytes for lithium batteries, which we would like to submit for publication on Journal of Power Sources.
Ionic Liquids (ILs)-based Electrolytes System for Lithium Ion Batteries
IOP Conference Series: Materials Science and Engineering
Electrolytes system plays an important part in Lithium Ion Batteries (LIBs) due to its role in lithium ion (Li+) transport between anode and cathode. Commercial LIBs use organic carbonates-based electrolytes system, but these electrolytes are flammable and volatile. For these reasons, replacement with non-flammable, non-volatile and high conductive compounds become recent research focus. Owing to the excellent properties, ILs are expected to cover the limitation of the organic-based electrolytes system in LIBs. The conductivity of electrolytes system which consists of dimethyl carbonate (DMC)/diethyl carbonate (DEC) (1:1, v/v) as organic solvent (OS) and imidazolium-based ILs is measured at various temperatures. Furthermore, the thermal stability of the electrolytes and the redox properties of lithium ion in IL-based electrolytes system are also investigated. [bmim][BF4]-based electrolyte yields a conductivity of ~13 mS cm−1 at 20 °C which is 10,000 times higher than DMC/DEC based o...
Ionic liquids as electrolytes for Li-ion batteries--An overview of electrochemical studies
Journal of Power Sources, 2009
The paper reviews properties of room temperature ionic liquids (RTILs) as electrolytes for lithium and lithium-ion batteries. It has been shown that the formation of the solid electrolyte interface (SEI) on the anode surface is critical to the correct operation of secondary lithium-ion batteries, including those working with ionic liquids as electrolytes. The SEI layer may be formed by electrochemical transformation of (i) a molecular additive, (ii) RTIL cations or (iii) RTIL anions. Such properties of RTIL electrolytes as viscosity, conductivity, vapour pressure and lithium-ion transport numbers are also discussed from the point of view of their influence on battery performance.
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.