Structural and dynamical properties of polymer electrolytes PPOLiClO4

Carlsson, Patrik; Swenson, Jan; McGreevy, R.L.; Gabrys, Barbara J.; Howells, W.S.; Börjesson, Lars; Torell, L. M.

doi:10.1016/s0921-4526(96)00922-2

Cited by 18 publications

(18 citation statements)

References 13 publications

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“…In the past, various experimental methods were used to characterize structure and dynamics of the PPO-LiClO 4 system. Small angle neutron scattering indicated that there are no structural inhomogeneities on a length scale of several nanometers, 13 in harmony with the interpretation of data from coherent quasielastic neutron scattering ͑QENS͒. 7,8 For such intermediate salt concentrations, differential scanning calorimetry ͑DSC͒ revealed two glass transition steps, [9][10][11] suggesting a liquid-liquid phase separation into salt-rich and salt-depleted regions.…”

Section: Introductionsupporting

confidence: 67%

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Ion and polymer dynamics in polymer electrolytes PPO-LiClO4. I. Insights from NMR line-shape analysis

Vogel

Torbrügge

2006

The Journal of Chemical Physics

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We investigate ion and polymer dynamics in polymer electrolytes PPO-LiClO4 performing 2H and 7Li NMR line-shape analysis. Comparison of temperature dependent 7Li and 2H NMR spectra gives evidence for a coupling of ion and polymer dynamics. 2H NMR spectra for various salt concentrations reveal a strong slowdown of the polymer segmental motion when the salt content is increased. The 2H NMR line shape further indicates that the segmental motion is governed by dynamical heterogeneities. While the width of the distribution of correlation times G(log tau) is moderate for low and high salt content, an extremely broad distribution exists for an intermediate salt concentration of 15:1 PPO-LiClO4. For the latter composition, a weighted superposition of two spectral components, reflecting the fast and the slow polymer segments of the distribution, describes the 2H NMR line shape over a broad temperature range. Analysis of the temperature dependent relative intensity of both spectral components indicates the existence of a continuous rather than a discontinuous distribution G(log tau). Such continuous distribution is consistent with gradual fluctuations of the local salt concentration and, hence, of the local environments of the polymer segments, whereas it is at variance with the existence of large salt-depleted and salt-rich domains featuring fast and slow polymer dynamics, respectively. Finally, for all studied PPO-LiClO4 mixtures, the 2H NMR line shape strongly depends on the echo delay in the applied echo-pulse sequence, indicating that the structural relaxation of the polymer segments involves successive rotational jumps about small angles gamma < 20 degrees .

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Section: Introductionsupporting

confidence: 67%

“…Following the common nomenclature in the literature, 8,[13][14][15]21 we disregard the difference between PPO and PPG and refer to the studied polymer as PPO. PPO ͑M w = 6510 g / mol͒ and LiClO 4 were purchased from Polymer Source Inc. and Aldrich, respectively.…”

Section: Methodsmentioning

confidence: 99%

Ion and polymer dynamics in polymer electrolytes PPO-LiClO4. I. Insights from NMR line-shape analysis

Vogel

Torbrügge

2006

The Journal of Chemical Physics

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“…19 However, at high silver salt concentrations, the free anion concentration becomes high and their electrostatic repulsion becomes stronger, pushing the polymer chains apart. 38,39 When the repulsion force by the anions is higher than the attractive "pulling-in" one by the silver cations coordination, the interchain distance would be increased. [37][38][39] However, the monotonic decrease in the distance from the second peak appears to be due to the coordinative interaction of silver cations with carbonyl oxygens.…”

Section: Carrier Propertiesmentioning

confidence: 99%

Silver polymer electrolyte membranes for facilitated olefint transport: carrier properties, transport mechanism and separation performance

2004

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Facilitated transport membranes for the separation of olefin/paraffin mixtures have long been of interest in separation membrane science because olefins, such as propylene and ethylene, which are important chemicals in petrochemical industries, are currently separated by energy-intensive cryogenic distillation processes. Recently, solid polymer electrolyte membranes containing silver ions have demonstrated remarkable performance in the separation of olefin/paraffin mixtures in the solid state and, thus, they can be considered as alternatives to cryogenic distillation. Here, we review recent progress, and critical issues affecting in the use of facilitated olefin transport membranes; in particular, we provide a general overview with reference to carrier properties, transport mechanisms, and separation performance.

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“…Quasielastic neutron scattering measurements on the PPO-LiClO 4 complex have confirmed this effect, but because of the limited energy resolution it was impossible to obtain quantitative results for the effect of solvated salt on the structural relaxation. 4 Londono et al 5 have performed neutron diffraction with isotopic Li substitution in combination with MD simulations in order to determine the partial pair distribution function g Li,O (r). They obtained a Li-O coordination number of about 3.5 for PEOLiI ͑O:Mϭ5, which is the number of ether oxygens of the polymer chain per metal ion͒, confirming crosslinking between cations and ether oxygens.…”

confidence: 99%

The dynamics in polyethyleneoxide–alkali iodide complexes investigated by neutron spin-echo spectroscopy and molecular dynamics simulations

Mos

Verkerk

Pouget

et al. 2000

The Journal of Chemical Physics

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We determined the self part of the intermediate scattering function in liquid polyethyleneoxide ͑PEO͒ and PEO-alkali iodide complexes by means of neutron spin-echo spectroscopy and molecular dynamics ͑MD͒ computer simulations. We present the first accurate quantitative results on the segmental dynamics in the time range up to 1 ns and the wave-vector range from a few nm Ϫ1to approximately 20 nm Ϫ1 . We investigate the influence of polymer chain length, salt concentration, and cation type. We find that the neutron data and MD data for pure PEO agree very well. A relatively small concentration of dissolved salt ͑1 metal ion per 15 monomers͒ leads to a slowing down of the segmental motions by an order of magnitude. Here, the MD simulations agree qualitatively. Increasing the chain length from 23 to 182 monomers has no significant effect except at the highest salt concentration. Similarly, changing the cation from Li to Na hardly makes any difference. The Rouse model does not adequately describe our data. © 2000 American Institute of Physics. ͓S0021-9606͑00͒51525-6͔ Amorphous polymer electrolytes provide an environment-friendly alternative for liquid electrolytes used in batteries, fuel cells, electrochemical displays, and chemical sensors.1 A polymer electrolyte is a complex of a polar polymer with a metal salt. In order to optimize performance of applications, it is of fundamental importance to understand the mechanism of ion transport, which is closely coupled to the segmental motions of the polymer chain. The systems most studied are poly͑ethyleneoxide͒ ͑PEO͒ and poly͑propyleneoxide͒ ͑PPO͒ salt complexes.From Brillouin light scattering of PPO-salt systems 2 and MD simulations of PEO-NaI systems 3 it appears that the Na ϩ ions form crosslinks between different oxygen atoms within a polymer chain, which causes slowing down of movement of polymer segments. Quasielastic neutron scattering measurements on the PPO-LiClO 4 complex have confirmed this effect, but because of the limited energy resolution it was impossible to obtain quantitative results for the effect of solvated salt on the structural relaxation.4 Londono et al. 5 have performed neutron diffraction with isotopic Li substitution in combination with MD simulations in order to determine the partial pair distribution function g Li,O (r). They obtained a Li-O coordination number of about 3.5 for PEOLiI ͑O:Mϭ5, which is the number of ether oxygens of the polymer chain per metal ion͒, confirming crosslinking between cations and ether oxygens. It has been shown that the conductivity characteristics for PPO-Li salt and PPO-Na salt are very similar.6 Therefore, we expect that the influence of Li and Na on the polymer dynamics in PEO is similar.Until today, no quantitative results were available on the local dynamics of the backbone segments of the polymer nor on the influence of various parameters such as salt concentration, polymer chain length, and different ions. Neutron spin echo ͑NSE͒ is the technique of choice regarding energy resolution and wave-vector rang...

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Structural and dynamical properties of polymer electrolytes PPOLiClO4

Cited by 18 publications

References 13 publications

Ion and polymer dynamics in polymer electrolytes PPO-LiClO4. I. Insights from NMR line-shape analysis

Ion and polymer dynamics in polymer electrolytes PPO-LiClO4. I. Insights from NMR line-shape analysis

Silver polymer electrolyte membranes for facilitated olefint transport: carrier properties, transport mechanism and separation performance

The dynamics in polyethyleneoxide–alkali iodide complexes investigated by neutron spin-echo spectroscopy and molecular dynamics simulations

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