Polymeric Electrolytes and Polyelectrolytes: Salt Concentration and Domain Effects on Conductivity

MRS Proceedings ◽

10.1557/proc-135-13 ◽

1988 ◽

Vol 135 ◽

Author(s):

Mark A. Ratner ◽

Stephen D. Druger ◽

A. Nitzan

Keyword(s):

Ion Pairs ◽

Frictional Drag ◽

Ionic Concentrations ◽

Ion Interactions ◽

Hückel Theory ◽

Bjerrum Length ◽

Polymeric Electrolytes ◽

Anion Separation ◽

Poly Propylene ◽

Applied Fields

AbstractSolvent-free polymer electrolytes and polyelectrolytes are usually studied at quite high ionic concentrations, (into the range above 1M). Under these conditions, correlation effects arising from ion-polymer and ion-ion interactions are expected to be important in the mechanism of conductivity. We sketch some specific ionic effects, separating those actittg on the mobility from those effecting carrier concentration. Mobility effects include reduction of the fluidity due to the effective cross-linking by cations, screening of applied fields due to high ionic concentrations, frictional drag due to counterion motion, and in some polymer hosts, lowered local availability of cation solvation sites due to reduction of the number of coordinating basic oxygens. Reduction of the carrier density from its stoichipmetric value can be discussed in terms of a generalized ion-pairing model. Though the concentrations usually studied are so high that Debye-Huckel theory is invalid and the stoichiometric average cation-anion separation is smaller than the Bjerrum length (a situation in which ordinary electrolyte theory considers all ions paired), nevertheless consideration in terms of contact ion pairs, solvent separated ion pairs and mean stoichiometric separation can be used to compute the effective concentration of carriers. Estimates based on an electrostatic continuum, cavity model for the binding energy of a pair describe the reduction of effective carrier number observed in poly (propylene oxide) materials.

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Ion Association in Polymer Electrolytes; A Raman Study of Poly (Propylene Oxide) Based Complexes

MRS Proceedings ◽

10.1557/proc-135-351 ◽

1988 ◽

Vol 135 ◽

Cited By ~ 3

Author(s):

M. Kakihana ◽

S. Schantz ◽

L.M. Torell ◽

L. Borjesson

Keyword(s):

Salt Concentration ◽

Ion Pairs ◽

Ion Association ◽

Major Effect ◽

Polymer Complexes ◽

Ion Interactions ◽

Different Temperatures ◽

Component Band ◽

Raman Study ◽

Poly Propylene

AbstractRaman spectra of a series of PPO-LiClO4 and PPO-NaCF3SO3 complexes have been obtained for different temperatures and salt concentrations to study the various ion associations of the dopant salt. It was found that ion-ion interactions dramatically influenced the internal symmetric stretching modes ν1 of the anions. Splitting of ν1 into a multicomponent band was observed. The intensity profile of the band was found to change rapidly with salt concentration and temperature. A three component band analysis led to the identification of dissociated ions, ion pairs and multiple ion aggregates, respectively. Increased ion association with increased temperature and/or salt concentration was observed for both LiCIO4- and NaCF3SO3- complexes. It is likely to initiate the phase separation and salt precipitation observed in many salt-polymer complexes at higher temperatures. Considerably stronger ion-ion interaction was observed in the NaCF3SO3-system than in the LiCIO4-complex, which may explain the lower conductivities reported for PPO-NaCF3SO3 electrolytes. The drastic conductivity drop observed in both systems at higher salt concentrations can however only partly be due to a decreased concentration of “free” ions, the major effect being attributed to decreased ion mobility.

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A comparison of acetone and poly(propylene glycol) as solvents for lithium triflate and lithium perchlorate

Canadian Journal of Chemistry ◽

10.1139/v91-285 ◽

1991 ◽

Vol 69 (12) ◽

pp. 1980-1984 ◽

Cited By ~ 28

Author(s):

James R. Stevens ◽

Per Jacobsson

Keyword(s):

Propylene Glycol ◽

Ion Pairs ◽

Lithium Perchlorate ◽

Lithium Triflate ◽

Free Ions ◽

Lower Dielectric Constant ◽

Current Controversy ◽

Raman Modes ◽

Poly Propylene ◽

Key Words Acetone

Solutions of LiCF3SO3 and LiClO4 in acetone and in poly(propylene glycol) (PPG 400 and PPG 4000) have been compared by studying the nondegenerate, symmetric stretch (A1,SO3) and (A1,ClO4) Raman modes. The Raman spectra contain bands due to the symmetric stretching motion of the "free" anion and due to the symmetric stretching motion of anions in ion aggregates. It is concluded that "free" ions, ion pairs, triplets, and aggregates are present. Although PPG has a much lower dielectric constant, it is a better solvent for these salts than the dipolar aprotic acetone. These findings have ramifications on the current controversy of whether "free" ions are present at all in polyether–salt complexes such as PPG 4000/LiCF3SO3. Key words: acetone, poly(propylene glycol), lithium triflate, lithium perchlorate, Raman.

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Evidence of dissolved ions and ion pairs in dilute poly (propylene oxide)-salt solutions

Solid State Ionics ◽

10.1016/0167-2738(93)90273-6 ◽

1993 ◽

Vol 60 (1-3) ◽

pp. 47-53 ◽

Cited By ~ 35

Author(s):

S SCHANTZ ◽

L TORELL

Keyword(s):

Propylene Oxide ◽

Ion Pairs ◽

Salt Solutions ◽

Dissolved Ions ◽

Poly Propylene

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Self-assembly of molecular ions via like-charge ion interactions and through-space defined organic domains

Chemical Communications ◽

10.1039/c7cc06401b ◽

2017 ◽

Vol 53 (79) ◽

pp. 10934-10937 ◽

Cited By ~ 11

Author(s):

J. S. McNally ◽

X. P. Wang ◽

C. Hoffmann ◽

A. D. Wilson

Keyword(s):

Aqueous Solution ◽

Self Assembly ◽

Ion Pairs ◽

Molecular Ions ◽

Ion Interactions ◽

Hydrogen Bonded

Select tertiary ammonium bicarbonates self-assemble assisted by the first bicarbonate like-charge hydrogen-bonded ion pairs documented in an aqueous solution.

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Amorphous Structure of Poly(Propylene Glycol) Electrolytes

Materials Science Forum ◽

10.4028/www.scientific.net/msf.480-481.273 ◽

2005 ◽

Vol 480-481 ◽

pp. 273-280

Author(s):

Glaura Goulart Silva ◽

Patterson Patrício de Souza ◽

Ana Júlia Silveira Mizher ◽

Marcos A. Pimenta

Keyword(s):

Glass Transition ◽

Salt Concentration ◽

Raman Band ◽

Ion Pairs ◽

Ionic Species ◽

Amorphous Structure ◽

Ionic Association ◽

Scanning Calorimetry ◽

Modulated Differential Scanning Calorimetry ◽

Poly Propylene

Changes in glass transition and ionic association of PPG/LiClO4 samples with increasing salt concentration have been studied using temperature modulated differential scanning calorimetry (TMDSC)and micro Raman spectroscopy, respectively. PPG, of average molar mass of 3000, was used as host for LiClO4 over the range O:Li = 35 – 4. The analysis of the Raman band, obtained at room temperature, associated with the ν1 symmetric stretching mode of ClO4 - anions, shows the presence of ionic association (ion pair) for electrolytes with salt concentration higher than O:Li = 8. The glass transition changes in the electrolytes were investigated using the differential of heat capacity with respect to temperature [dCp/dT], obtained from TMDSC. The analysis of the dCp/dT signal, by fitting with Gaussian curves, showed that there is a glass transition splitting in samples with concentrations higher than O:Li = 16, which indicates the presence of nanoheterogeneities in these amorphous electrolytes. Raman results pemit to affirm that this nanoheterogeneities were associated mainly with solvent separated ion pairs regions of different concentrations, and not with aggregate of ionic species.

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A Molecular Dynamics Study of the Structure of an LiCl · 4 H2O Solution

Zeitschrift für Naturforschung A ◽

10.1515/zna-1985-0203 ◽

1985 ◽

Vol 40 (2) ◽

pp. 116-125 ◽

Cited By ~ 50

Author(s):

Philippe Bopp ◽

Isao Okada ◽

Hitoshi Ohtaki ◽

Karl Heinzinger

Keyword(s):

Md Simulation ◽

Pure Water ◽

Ion Pairs ◽

Water Molecules ◽

Force Model ◽

X Ray Diffraction ◽

X Ray ◽

Lennard Jones ◽

Ion Interactions ◽

Contact Ion Pairs

A study of the structure of a 13.9molal aqueous LiCl solution has been performed by MD simulation. An improved central force model was used for water. The ion-water interactions were derived from ab initio calculations, while the ion-ion interactions were described by charged Lennard-Jones spheres. The structure function obtained from the simulation agrees reasonably well with that of X-ray diffraction. The number of first neighbour water molecules around an Li+ is estimated to be about 5, as compared with a coordination number of about 4 derived from X-ray measurements. A small amount of contact ion pairs is suggested to exist. The O - H distance is increased by about 0.014 Å relative to pure water, resulting in a red shift of the O - H stretching frequency of about 300 cm-1.

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Facet Topography and Dislocation Structure as a Possible Source for Electrical Heterogeneity in [001] TILT Bicrystals of YBa2Cu3O7-δ

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100164155 ◽

1996 ◽

Vol 54 ◽

pp. 338-339

Author(s):

I-Fei Tsu ◽

D.L. Kaiser ◽

S.E. Babcock

Keyword(s):

Grain Boundary ◽

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Electromagnetic Properties ◽

Length Scale ◽

Density Values ◽

Current Densities ◽

Applied Fields ◽

A Current

A current theme in the study of the critical current density behavior of YBa2Cu3O7-δ (YBCO) grain boundaries is that their electromagnetic properties are heterogeneous on various length scales ranging from 10s of microns to ˜ 1 Å. Recently, combined electromagnetic and TEM studies on four flux-grown bicrystals have demonstrated a direct correlation between the length scale of the boundaries’ saw-tooth facet configurations and the apparent length scale of the electrical heterogeneity. In that work, enhanced critical current densities are observed at applied fields where the facet period is commensurate with the spacing of the Abrikosov flux vortices which must be pinned if higher critical current density values are recorded. To understand the microstructural origin of the flux pinning, the grain boundary topography and grain boundary dislocation (GBD) network structure of [001] tilt YBCO bicrystals were studied by TEM and HRTEM.

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