Search results for "Polymer electrolytes"

Dynamic heterogeneity in polymer electrolytes. Comparison between QENS data and MD simulations

2001

Abstract We have investigated the dynamics of poly(ethylene oxide) (PEO) lithium-based salt electrolytes (PEO–LiBETI) using quasi-elastic neutron scattering (QENS). Measurements were carried out on the spectrometer NEAT (HMI, Berlin) above the melting temperature of PEO ( T m ≈65°C). The experimental data fully support the Molecular Dynamics (MD)-derived model of a heterogeneous dynamics in dilute PEO-salt electrolytes. In agreement with MD simulations carried out on PEO–LiPF 6 , we find evidences for the existence of two dynamic processes: (a) a faster process that is described in terms of the pure PEO dynamics and (b) a second component which we identify with the slower motion of the PEO …

Influence of the anion on diffusivity and mobility of ionic liquids composite polybenzimidazol membranes

2020

[EN] The study of proton conductivity processes has received increasing attention in the past decades due to their potential applications in fields such as electrochemical devices and fuel cells. Despite the high number of composite membranes which have been described for this purpose, fundamental studies of the conduction phenomena in polymeric membranes are scarce. In this article, we study on the effect of the anion on ionic conductivity of ionic liquid composite polybenzimidazole (PBI) membranes. These membranes, which contain 1-butyl-3-methylimidazolium (BMIM) with different counterions ([Cl]-, [NCS]-, [NTf2]- and [BF4]-) were analyzed by electrochemical impedance spectroscopy (EIS) in…

Lithium ion conducting PVdF-HFP composite gel electrolytes based on N-methoxyethyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)-imide ionic li…

2010

Blends of PVDF-HFP and ionic liquids (ILs) are interesting for application as electrolytes in plastic Li batteries. They combine the advantages of the gel polymer electrolytes (GPEs) swollen by conventional organic liquid electrolytes with the nonflammability, and high thermal and electrochemical stability of ILs. In this work we prepare and characterize PVDF-HFP composite membranes swollen with a solution of LiTFSI in ether-functionalized pyrrolidinium-imide (PYRA12O1). The membranes are filled in with two different types of silica: i) mesoporous SiO2 (SBA-15) and a commercial nano-size one (HiSilTM T700). The ionic conductivity and the electrochemical properties of the gel electrolytes ar…

Polymer electrolytes based on PAN and mixed salts for photoelectrochemical appilcations: formulation and characterization

2012

Structural and dynamical characterization of melt PEO–salt mixtures

2002

Abstract Salt doped poly ethylene oxide (PEO) mixtures were investigated by means of both small angle neutron scattering and QENS techniques aiming to characterize morphological and dynamical features in the melt state. These experimental evidences provide support to the proposed heterogeneous scenario for polymer electrolytes. In particular, the existence of PEO–cation complexes is proposed to play a major role in intramolecular cooperation and intermolecular transient crosslinks, which affects the mixture properties.

Morphology of solid polymer electrolytes: a TR WAXS investigation

2002

A wide angle X-ray scattering investigation of (polyethylene oxide)n–sodium thiocyanate [(PEO)nNaSCN] mixtures is reported. Temperature dependence analysis for different mixtures is shown, in order to rationalize the multi-phase behaviour. Depending on the amount of salt added and upon the temperature considered three different phases have been found to simultaneously coexist: crystalline PEO, amorphous PEO, and crystalline complex.

Segmental dynamics in polymer electrolytes

2002

Polymer dynamics in poly(ethylene oxide) (PEO)–salt mixtures is investigated by means of quasi-elastic neutron scattering (QENS). In a previous study, we reported QENS data from the NEAT spectrometer (BENSC) that evidenced, for the first time, a dynamic heterogeneity in PEO–salt mixtures induced by salt addition. This finding is supported by molecular dynamics (MD) simulations carried out by Borodin et al. In agreement with MD simulations, our QENS data revealed two distinct processes: a fast motion corresponding to the bulk polymer and a slower relaxation, which we attribute to formation of PEO–cation complexes. In this paper we present new QENS data from the high-resolution spectrometer I…

Stable Light-Emitting Electrochemical Cells Using Hyperbranched Polymer Electrolyte

2021

The choice of an adequate electrolyte is a fundamental aspect in polymer light-emitting electrochemical cells (PLECs) as it provides the in situ electrochemical doping and influences the performance of these devices. In this study, a hyperbranched polymer (Hybrane DEO750 8500) blended with a Li salt is used as a novel electrolyte in state-of-the-art Super Yellow (a polyphenylenevinylene) based LECs. Due to the desirable properties of the hyperbranched polymer and the homogeneous and smooth films that it forms with the emitting polymer, PLEC with excellent electroluminescent properties are obtained using a pulsed current bias scheme. The devices are very stable, with lifetimes in excess of 2…