1,721,051 research outputs found
Safer electrolyte components for rechargeable batteries
No full textAmong the electrochemical energy storage systems, rechargeable lithium batteries are considered very promising candidates for the next generation power sources because of their high gravimetric and volumetric energy density with respect to other cell chemistries. The lithium-ion battery technology is based on the use of electrode materials able to reversibly intercalate lithium cations, which are continuously transferred between two host structures (negative and positive electrodes) during the charge and discharge processes. Commercial lithium-ion batteries commonly use liquid electrolytes based on suitable lithium salts (solute) and organic compounds (solvents). The latter, volatile and flammable, represent serious concerns for the safety of the electrochemical devices, this so far preventing their large diffusion in applications as automotive, storage from renewable sources, smart grids. One of the most appealing approaches is the partial or total replacement of the organic solvents with safer, less hazardous, electrolyte components. Here, a concise survey of ones of the most investigated types of alternative electrolyte components, proposed for safer and more reliable rechargeable lithium batteries, is reported. Graphical Abstract
Managing transport properties in composite electrodes/electrolytes for all-solid-state lithium-based batteries
No full textIn the global competition for ultimate electrochemical energy storage systems, the increasing tendency of original equipment manufacturers (OEM) worldwide is to consider solid-state technology as a solution to replace the current Li-ion batteries operating with liquid electrolytes. The reason for this is the need of enhanced energy density batteries which are also durable and inherently safe. Proper understanding of the electrode/electrolyte interface is of paramount importance for this purpose. Indeed, all-solid-state lithium-based secondary batteries require efficient ion conductive pathways through the whole thickness of the electrode to properly access all the active material particles, thus providing full electrode capacity. In this respect, here, we propose an overview of the strategies adopted to achieve this goal, including polymeric and inorganic ion conductors and composites thereof as well as their preparation procedures and characterisation techniques, which currently represent highly important topics in the academic/industrial community to provide solutions for the shortcomings of poor safety, low ion mobility and short cycle life
Ionic liquid electrolytes for safer and more reliable sodium battery systems
Full text linkNa+-conducting, binary electrolytic mixtures, based on 1-ethyl-3-methyl-imidazolium, trimethyl-butyl-ammonium, and N-alkyl-N-methyl-piperidinium ionic liquid (IL) families, were designed and investigated. The anions were selected among the per(fluoroalkylsulfonyl)imide families. Sodium bis(trifluoromethylsulfonyl)imide, NaTFSI, was selected as the salt. The NaTFSI-IL electrolytes, addressed to safer sodium battery systems, were studied and compared in terms of ionic conductivity and thermal stability as a function of the temperature, the nature of the anion and the cation aliphatic side chain length. Room temperature conductivities of interest for sodium batteries, i.e., largely overcoming 10-4 or 10-3 S cm-1, are displayed. Similar conduction values are exhibited by the EMI-based samples even below -10 °C, making these electrolyte mixtures potentially appealing also for low temperature applications. The NaTFSI-IL electrolytes, with the exception of the FSI-ones, are found to be thermally stable up to 275 °C, depending on the nature of the cation and/or anion, thus extending their applicability above 100 °C and remarkably increasing the reliability and safety of the final device, especially in the case of prolonged overheating
Influence of Alkyl Chain Length on Microscopic Configurations of the Anion in the Crystalline Phases of PYR1A-TFSI
No full textThe infrared spectra and their temperature dependence are
measured for a series of pyrrolidinium based ionic liquids (ILs) sharing the
bis(trifluoromethanesulfonyl)imide (TFSI) anion and having alkyl chains of
different length. While in the liquid or glassy state, both conformers of TFSI are
retained for all compounds, in the solid state a strong predominance of trans-TFSI
occurs in ionic liquids with alkyl chains shorter than five C−H groups; on the
contrary, for alkyl chain longer than six C−H groups crystalline phases display only
cis-TFSI, which is a rare configuration in solids. Moreover, a mixed system
composed of a short chain liquid (PYR14-TFSI) with one having a longer chain
(PYR18-TFSI) in a mass ratio of 1:1 is studied. The competition between the two
conformers of TFSI hinders the crystallization and gives rise to a glass transition
around 183 K
Explorative Approaches for Safer, Scalable, Lithium Battery Solid Electrolyte Technologies
No full textOne of the main drawbacks of commercial lithium-ion batteries is the safety issue because of the hazardous organic electrolyte compounds, especially in case of electric and/or mechanical abuse. With the aim of overcoming this limitation, two synergic approaches have been followed: i) replacement of the organic solvents with innovative, non-volatile and non-flammable fluids (ionic liquids); ii) confinement of the ionic liquid electrolytes within suitable polymeric hosts for obtaining solid-state, ionically conducting membranes. In the present work, the attention has been focused on the N1114FSI, EMIFSI and PYR14TFSI ionic liquids (combined with the LiTFSI salt), and the electro-spun PSU, PAN/PCL and PAN/PCL-OLG polymer hosts. This study presents an explorative approach for developing innovative thin-layer, solvent-free, scalable polymer electrolyte technologies from the safety and engineering points of views
Asymmetric ammonium-based ionic liquids as electrolyte components for safer, high-energy, electrochemical storage devices
No full textThe synthesis of ionic liquids (ILs), based on the trimethyl-isobuty-ammonium cation, (N111i4)+, and, respectively, the bis(trifluoromethylsulfonyl)imide (TFSI), (fluorosulfonyl) (trifluoromethylsulfonyl)imide (FTFSI), and bis(fluorosulfonyl)imide (FSI) anions is herein reported. The NMR validation of the N111i4Br precursor as well as the ionic liquids is shown. The thermal properties were investigated via variable-temperature, coupled with mass spectroscopy, and isothermal thermo-gravimetrical analyses, and long-thermal tests. The TFSI-based IL exhibits a melting point of 29.93 °C, which is found to be shifted down to −0.12 and −14.32 °C for the FSI- and FTFSI-based samples, respectively. Additionally, the TFSI- and FTFSI-based samples are able to keep in super cooled state for more than one year. The investigated N111i4-based ionic liquids display an electrochemical stability window exceeding 5.5 V
Ionic liquid electrolytes for room temperature sodium battery systems
No full textSafer electrolytes for ambient temperature sodium batteries were prepared by blending the N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, PYR 14 TFSI, ionic liquid with the sodium bis(trifluoromethylsulfonyl)imide, NaTFSI, salt. The physicochemical as well as the electrochemical properties of the PYR 14 TFSI-NaTFSI binary electrolyte system were investigated as a function of the temperature and sodium salt mole fraction, and compared with those of organic electrolytes of interest for sodium batteries. A plethora of characterization techniques were adopted ranging from density, viscosity and conductivity measurements, thermogravimetry and electrochemical methods (linear sweep voltammetry, transference number, galvanostatic experiments). Preliminary galvanostatic cycling tests were carried out in Na/NaMnO 2 cells at room temperature. The results are presented and discussed in the present paper
Physicochemical investigation on the hard carbon interface in ionic liquid electrolyte
No full textAn investigation of the solid electrolyte interphase (SEI) on hard carbon (HC) anodes in aprotic sodium batteries was carried out by post-mortem analyses. Electrodes cycled in 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI), and N-trimethyl-N-butylammonium bis(fluorosulfonyl)imide (N1114FSI) ionic liquid electrolytes have been collected and studied: benchmark electrodes cycled in commercial organic solutions were examined for comparison purpose. The SEI composition and morphology of post-mortem HC electrodes were analyzed by X-ray Photoelectron Spectroscopy (XPS) and focused ion beam scanning electron microscopy (FIB-SEM) analysis. Overall, the HC electrodes cycled in carbonate-based electrolyte have shown thicker SEI mainly composed of organic compounds, whereas in ILs electrolytes they have shown thinner layer richer in inorganic species, such as NaF, Na2CO3, N-containing species, and “small” sulfide-based compounds, these improving the SEI interfacial properties towards the Na+ migration kinetics. Focusing on ILs based cell formulations, anodes cycled in the EMIFSI-based electrolyte shows several cracks on its surface
Improved Compatibility of α-NaMnO2 Cathodes at the Interface with Ionic Liquid Electrolytes
No full textThe behaviour and compatibility of monoclinic sodium manganite, α-NaMnO2, cathodes at the interface with electrolytes based on the 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMIFSI) and N-trimethyl-N-butylammonium bis(fluorosulfonyl)imide (N1114FSI) ionic liquids is presented and discussed. The Na+ insertion process was analysed through cyclic voltammetry tests combined with impedance spectroscopy measurements and the cell performance was tested by charge-discharge cycles. XPS and FIB-SEM measurements allowed analysis of the surface composition and the morphology of post-mortem cathodes. Overall, the α-NaMnO2 cathode showed high reversibility in N1114FSI-based electrolyte, delivering 60 % of the initial capacity after 1200 cycles in conjunction with a Coulombic efficiency above 99 %. To our knowledge, these very promising results are the best result obtained till now for monolithic α-NaMnO2 cathodes, are ascribable to the formation of a stable passive layer onto the electrode surface, as confirmed by spectroscopic analysis
Sodium-Conducting Ionic Liquid Electrolytes: Electrochemical Stability Investigation
Full text linkSodium-conducting electrolytes, based on the EMIFSI, EMITFSI, N1114FSI, N1114TFSI, N1114IM14, PIP13TFSI and PIP14TFSI ionic liquids, were investigated in terms of electrochemical stability through voltammetry techniques with the aim of evaluating their feasibility in Na-ion devices. Both the anodic and cathodic sides were studied. The effect of contaminants, such as water and/or molecular oxygen, on the electrochemical robustness of the electrolytes was also investigated. Preliminary cyclic voltammetry and charge-discharge tests were carried out in Na/hard carbon and Na/α-NaMnO2 half cells using selected ionic liquid electrolytes. The results are presented and discussed in the present paper
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