1,721,006 research outputs found
High-performance electrolyte membranes for plastic lithium batteries
No full textThe synthesis, properties, and application of new types of lithium-ion conducting polymeric membranes are reported and discussed. These ionic membranes are dimensionally stable, have a very high ionic conductivity, an acceptable lithium-ion transference number and a wide electrochemical stability window. Due to these favourable properties, these membranes are suitable for the fabrication of advanced-design, high-performance batteries and power source devices
Kinetics and Stability of the Lithium Electrode In Poly(methylmethacrylate)-based Gel Electrolytes
No full textThe transport and electrochemical properties of gel-type ionic conducting membranes formed by immobilizing liquid solutions of lithium salts in a poly(methylmethacrylate) matrix have been determined. In particular, the conductivity, the lithium ion transference number and the electrochemical stability window are evaluated and discussed. Finally, particular attention is devoted to the phenomena occuring at the interface between these ionic membranes and the lithium metal electrode
Raman Study of Ion-Molecules Interaction in Poly(Methylmetacrylate)-Based Gel Electrolytes
No full textGel electrolytes have been obtained, containing LiX (X = ClO(4), N(CF(3)SO)(2), AsF(6)) dissolved in a ethylene carbonate-propylene carbonate mixture and PMMA as polymeric matrix. Ionic conductivity has been measured, for two different lithium salts. The changes in the Raman spectra have been studied as a function of the polymer content, lithium salt concentrations and for different anions. Two satellite bands of the internal bending and stretching modes of ethylene carbonate appear in the spectrum of lithium containing samples, because of the cation-solvent molecule interaction
Hot-pressed, Dry, Nanocomposite, PEO-based Electrolyte Membranes. Ionic Conductivity Characterization and Battery Tests
Full text linkhttp://www.electrochem.org/dl/ma/203/pdfs/0098.pd
Hybrid supercapacitors with ionic liquids as solvent-free electrolytes
No full textIonic liquids (ILs) are receiving great attention as solvent-free "green" electrolytes for high voltage supercapacitors because of their very low vapour pressure, wide electrochemical stability window and good conductivity at operating temperatures of supercapacitors-PEM fuel cell coupled systems for automotive application. We pursued the strategy of using ILs in hybrid supercapacitors with activated carbon (AC) as the negative electrode and poly(3-methylthiophene) (pMeT) as the positive, and we demonstrated the cycling stability over more than 15,000 galvanostatic cycles at 60°C of the supercapacitor with pyrrolidinium-based ionic liquid electrolyte. This result, obtained with high-purity IL, was achieved with still not-optimized electrode materials. Here we present and discuss the results of our study for the optimization of AC/IL/pMeT hybrid supercapacitor components
High-performance gel-type lithium electrolyte membranes
No full textBattery-grade solution products have been used for the synthesis of new types of poly(acrylonitrile) PAN-based polymer electrolyte membranes. Basically, two classes of membranes have been prepared differing by the type of lithium salt in the ethylene carbonate-dimethyl carbonate (EC-DMC) solution trapped in the PAN matrix, i.e. LiPF6, or LiC(CF3SO2)(3) lithium methide salt, respectively. The results demonstrate that both classes of membranes have high conductivity and very good chemical and electrochemical stability. These unique characteristics make the membranes suitable for applications in high-voltage, rechargeable lithium batteries. (C) 1999 Elsevier Science S.A. All rights reserved
Structural Organization and Transport Properties of Novel Pyrrolidinium-Based Ionic Liquids with Perfluoroalkyl Sulfonylimide Anions
No full textRoom-temperature ionic liquids (RTILs) based on the N-butyl-N-methyl pyrrolidinium cation (PYR14+) combined with three different fluorinated anions have been prepared and characterized by NMR, conductivity, and rheological measurements. The anions are (trifluoromethanesulfonyl)(nonafluorobutanesulfonyl)imide (IM14−), bis(pentafluoroethanesulfonyl)imide (BETI−), and bis(trifluoromethanesulfonyl)imide (TFSI−). Intermolecular anion−cation nuclear Overhauser enhancements (NOEs) have been experimentally observed in all titled compounds. These findings indicate the formation of long-lived aggregates in the bulk liquids. The NOE patterns show marked selectivity and can be rationalized assuming that the perfluorinated moieties of the anions tend to adopt a preferential orientation with respect to the cations, with possible formation of mesoscopic fluorous domains. Self-diffusion coefficients D for the anion and the cation have been measured by DOSY NMR. Diffusion data show similar but not identical values for cation and anion, consistent with local ordering at the molecular level. The observed trend in diffusion coefficients, Dcation > Danion for all compounds, is compatible with a higher degree of intermolecular organization of the anions. This nanoscale organization is connected to rather strong deviations of the experimental conductivities from those estimated from the ion diffusion coefficients through the Nernst−Einstein relationship. The measured viscosities and ion diffusion coefficients in PYR14IM14 and in PYR14TFSI have similar temperature dependencies, leading to very close values of the activation energies for these processes. Ab initio density functional calculations on models of a PYR14TFSI ion pair lead to the identification of several local minima, whose structure and energy can be qualitatively related to the experimental NOE signals and activation energies
Electrode and electrolyte materials for plastic lithium ion batteries
No full textThe electrochemical behaviour of plasticised lithium-ion anode (i.e. graphite) and cathode (i.e. LiNiO2 and LiMn2O4) materials has been examined in the solid state by using polymer electrolytes. The investigation has been carried out in order to evaluate the suitableness of these materials for the fabrication of full plastic-like lithium-ion batteries. The results show that the response of the plsticised graphite electrode is strongly influenced by the conditions of the interface while less puzzling appears the response of the lithium metal oxide electrodes
Synthesis and Characterization of Highly Conducting Gel Electrolytes
No full textThe electrochemical properties of gel electrolytes formed by the immobilization in a poly(acrylonitrile) matrix of solutions of common lithium salts (eg LiClO4, LiAsF6 and LiN(CF3SO2)2) in organic solvents (eg the propylene carbonate-ethylene carbonate mixture, gamma-butyrolactone or the gamma-butyrolactone-ethylene carbonate mixture) have been determined. The results indicate that in accordance with previous literature data, these electrolytes have a high ionic conductivity, a wide electrochemical stability window and a high lithium transference number. However, their application in long-life, rechargeable lithium polymer batteries may be hindered by the instability of the negative electrode interface
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