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Enhancement of ion dissociation in polyelectrolyte gels
journal contribution
posted on 2003-06-30, 00:00 authored by Maria ForsythMaria Forsyth, J Sun, F Zhou, D MacFarlaneHigh conductivity in single ion conducting polymer electrolytes is still the ultimate aim for many electrochemical devices such as secondary lithium batteries. Achieving effective ion dissociation in these cases remains a challenge since the active ion tends to remain in close proximity to the backbone charge as a result of a low degree of ion dissociation. A unique aspect of this dissociation problem in polyelectrolytes is the repulsion between the backbone charges created by dissociation. One way of enhancing ion dissociation in polyelectrolyte systems is to use copolymers in which only a fraction (<20%) of the mer units are charged and where the comonomer is itself chosen to be polar and preferably to be compatible with potential solvents. We have also found that certain dissociation enhancers based on ionic liquids or boroxine ring compounds can lead to high ionic conductivity. In the cases where an ionic liquid is used as the solvent in a polyelectrolyte gel, the viscosity of the ionic liquid and its hydrophilicity are critical to achieving high conductivity. Compounds based on the dicyanamide anion appear to be very effective ionic solvents; polyelectrolyte gels incorporating such ionic liquids exhibit conductivities as high as 10ā2 S/cm at room temperature. In the case of boroxine ring dissociation enhancers, gels based on poly(lithium-2-acrylamido-2-methyl-1-propanesulfonate) and ethylene carbonate produce conductivities approaching 10ā3 S/cm. This paper will discuss these approaches for achieving higher conductivity in polyelectrolyte materials and suggest future directions to ensure single ion transport.
History
Journal
Electrochimica actaVolume
48Issue
14-16Pagination
2129 - 2136Publisher
Elsevier Science Pub. Co.Location
New York, N.Y.Publisher DOI
ISSN
0013-4686eISSN
1873-3859Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2003, Elsevier Science LtdUsage metrics
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