title: Molecular mobility and Li(+) conduction in polyester copolymer ionomers based on poly(ethylene oxide).
abstract: We investigate the segmental and local dynamics as well as the transport of Li(+) cations in a series of model poly(ethylene oxide)-based single-ion conductors with varying ion content, using dielectric relaxation spectroscopy. We observe a slowing down of segmental dynamics and an increase in glass transition temperature above a critical ion content, as well as the appearance of an additional relaxation process associated with rotation of ion pairs. Conductivity is strongly coupled to segmental relaxation. For a fixed segmental relaxation frequency, molar conductivity increases with increasing ion content. A physical model of electrode polarization is used to separate ionic conductivity into the contributions of mobile ion concentration and ion mobility, and a model for the conduction mechanism involving transient triple ions is proposed to rationalize the behavior of these quantities as a function of ion content and the measured dielectric constant.
authors.affiliation: Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Fragiadakis
authors.forename: Shichen
authors.initials: S
authors.lastname: Dou
authors.forename: Ralph H
authors.initials: RH
authors.lastname: Colby
authors.forename: James
authors.initials: J
authors.lastname: Runt