Ionic liquids and their modification with lithium salts –synthesis and studies (original) (raw)
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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 and their derivatives for lithium batteries: role, design strategy, and perspectives
Energy Materials, 2023
Lithium-ion batteries (LIBs) are the predominant power source for portable electronic devices, and in recent years, their use has extended to higher-energy and larger devices. However, to satisfy the stringent requirements of safety and energy density, further material advancements are required. Due to the inherent flammability and incompatibility of organic solvent-based liquid electrolytes with materials utilized in high energy devices, it is necessary to transition to alternative conductive mediums. The focus is shifting from molecular materials to a class of materials based on ions, including ionic liquids (ILs) and their derivatives such as zwitterionic ILs, polymerized ILs, and solvated ILs, which possess high levels of safety, stability, compatibility, and the ability to rationally design ILs for specific applications. Ion design is crucial to achieve superior control of electrode/electrolyte interphases (EEIs) both on anode and cathode surfaces to realize safer and higher-energy lithium-metal batteries (LMBs). This review summarizes the different uses of ILs in electrolytes (both liquid and solids) for LMBs, reporting the most promising results obtained during the last years and highlighting their role in the formation of suitable EEIs. Furthermore, a discussion on the use of deep-eutectic solvents is also provided, which is a class of material with similar properties to ILs and an important alternative from the viewpoint of sustainability. Lastly, future prospects for the optimization of IL-based electrolytes are summarized, ranging from the functional design of ionic structures to the realization of nanophases with specific features.
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...
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.
The Journal of Physical Chemistry B, 2018
To compare 1-butyl-3-methylimidazolium ([BMIM] +) and 1-butyl-3-methylpyridinium ([BMPy] +)-based ionic liquids (ILs) and investigate the influence of intramolecular and intermolecular interactions on physicochemical properties, a systematic study was performed on the electronic structures and physicochemical properties of [BMIM] + tetrafluoroborate ([BMIM][BF 4 ]), [BMIM] + hexafluorophosphate ([BMIM][PF 6 ]), [BMIM] + hydrogen sulfate ([BMIM][HSO 4 ]), [BMIM] + methylsulfate ([BMIM][MSO 4 ]), [BMIM] + ethylsulfate ([BMIM][ESO 4 ]), [BMPy] + tetrafluoroborate ([BMPy][BF 4 ]), [BMPy] + hexafluorophosphate ([BMPy][PF 6 ]), [BMPy] + hydrogen sulfate ([BMPy][HSO 4 ]), [BMPy] + methylsulfate ([BMPy][MSO 4 ]), and [BMPy] + ethylsulfate ([BMPy][ESO 4 ]) using density functional theory and molecular dynamics simulation. The results reveal that aggregation behavior exists in [HSO 4 ]and [ESO 4 ]-based ILs, and the differences between their densities and self-diffusion coefficients are smaller when there is an aggregation effect in ILs. A dimer is formed by two strong hydrogen bonds between two [HSO 4 ]anions in [HSO 4 ]-based ILs, and the existence of hydrogen bonds in ILs increases density and decreases self-diffusion coefficient. The intermolecular interaction strength of [BMIM] +-based ILs is stronger than that of [BMPy] +-based ILs.