Ion Pairing and Ionic Conductivity in Amorphous Polymer Electrolytes: a Structural Investigation Employing EXAFS

Pollock, David W.; Williamson, Kelly J.; Weber, Kara; Lyons, Leslie J.; Sharpe, Lee R.

doi:10.1021/cm00047a004

Cited by 6 publications

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References 1 publication

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“…The accepted mechanism of the ionic conductivity involves the mobile ions moving from one polymer chain to another by a chain-flexing process called segmental motion [77]. To clarify the issue of whether the driving force for dissociation (association) of positively/negatively charged ions, H 3 O + and SO 3 − , is dominantly of energetic or entropic nature, we examined the temperature dependence of pair correlation functions (PCFs) g +– ( r ) and the corresponding potential of mean force W +– ( r ) = – k B T ln g +– ( r ).…”

Section: Resultsmentioning

confidence: 99%

Large-scale atomistic and quantum-mechanical simulations of a Nafion membrane: Morphology, proton solvation and charge transport

Комаров¹,

Khalatur²,

Khokhlov³

2013

Beilstein J. Nanotechnol.

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SummaryAtomistic and first-principles molecular dynamics simulations are employed to investigate the structure formation in a hydrated Nafion membrane and the solvation and transport of protons in the water channel of the membrane. For the water/Nafion systems containing more than 4 million atoms, it is found that the observed microphase-segregated morphology can be classified as bicontinuous: both majority (hydrophobic) and minority (hydrophilic) subphases are 3D continuous and organized in an irregular ordered pattern, which is largely similar to that known for a bicontinuous double-diamond structure. The characteristic size of the connected hydrophilic channels is about 25–50 Å, depending on the water content. A thermodynamic decomposition of the potential of mean force and the calculated spectral densities of the hindered translational motions of cations reveal that ion association observed with decreasing temperature is largely an entropic effect related to the loss of low-frequency modes. Based on the results from the atomistic simulation of the morphology of Nafion, we developed a realistic model of ion-conducting hydrophilic channel within the Nafion membrane and studied it with quantum molecular dynamics. The extensive 120 ps-long density functional theory (DFT)-based simulations of charge migration in the 1200-atom model of the nanochannel consisting of Nafion chains and water molecules allowed us to observe the bimodality of the van Hove autocorrelation function, which provides the direct evidence of the Grotthuss bond-exchange (hopping) mechanism as a significant contributor to the proton conductivity.

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Section: Resultsmentioning

confidence: 99%

Large-scale atomistic and quantum-mechanical simulations of a Nafion membrane: Morphology, proton solvation and charge transport

Комаров¹,

Khalatur²,

Khokhlov³

2013

Beilstein J. Nanotechnol.

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“…The formation of positively and/or negatively charged ion triplets has also been observed at higher concentrations of salts. The ion-pair formation at a high salt concentration has been verified by many workers [36][37][38][39][40][41][42] which restricts the maximum obtainable ionic conductivity in these systems. The concept that ionic conductivity in these systems is predominantly due to motion of ions in its amorphous region is supported by the observation that beyond 70 °C (i.e.…”

Section: Classification/types Of Polymer Electrolytementioning

confidence: 90%

Conductivity Modulation in Polymer Electrolytes and their Composites due to Ion-Beam Irradiation

Singh

Bhattacharya

Virk

2015

SSP

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Polymers are a class of materials widely used in different fields of applications. With imminent applications of polymers, the study of radiation induced changes in polymers has become an obvious scientific demand. The bombardment by ion beam radiations has become one of the most promising techniques in present day polymer research. When the polymers are irradiated, a variety of physical and chemical changes takes place due to energy deposition of the radiation in the polymer matrix. Scissoring, cross-linking, recombination, radical decomposition, etc. are some of the interesting changes that are obvious in polymers. The modification in polymer properties by irradiation depends mainly on the nature of radiation and the type of polymer used.Polymer electrolytes are obtained by modifying polymers by doping, complexing, or other chemical processes. In general, they suffer from low conductivity due to high crystallinity of the matrix. The effect of radiation on polymer electrolyte is expected to alter their crystalline nature vis-a-vis electrical properties. This review article shall elaborate modifications in the physical and chemical properties of polymer electrolytes and their composites. The variations in properties have been explored on PEO based polymer electrolyte and correlated with the parameters responsible for such changes. Also a comparison with different types of the polymers irradiated with a wide range of ion beams has been established.

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Polyethylene glycol as a green chemical solvent

Hoffmann

2022

Current Opinion in Colloid & Interface Science

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Ion Pairing and Ionic Conductivity in Amorphous Polymer Electrolytes: a Structural Investigation Employing EXAFS

Cited by 6 publications

References 1 publication

Large-scale atomistic and quantum-mechanical simulations of a Nafion membrane: Morphology, proton solvation and charge transport

Large-scale atomistic and quantum-mechanical simulations of a Nafion membrane: Morphology, proton solvation and charge transport

Conductivity Modulation in Polymer Electrolytes and their Composites due to Ion-Beam Irradiation

Polyethylene glycol as a green chemical solvent

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