Correlations of Ion Motion and Chain Motion in Salt-in-Polysiloxane-g-oligoether Electrolytes

Abstract

The transport properties of salt and chains in a salt-in-polymer electrolyte consisting of polysiloxane-g-oligoether with different concentrations of lithium triflate, LiSO3CF3, are investigated. Temperature-dependent impedance spectroscopy, viscosity, and multinuclear self-diffusion NMR characterize the mobility of the chains and the different salt species, i.e., ion pairs or single ions. Comparison of different transport parameters allows conclusions about the motions of different species and correlations between them. For example, comparing diffusion coefficients and conductivities via the Nernst–Einstein equation, the fraction of undissociated ion pairs is concluded to be larger than 90%. Macroscopic and microscopic viscosities describe chain and small species motions, respectively. Distinct differences are observed between the temperature-dependence of the transport parameters of ion pairs, which is of Arrhenius-type, and that of the transport of chains or single ions, which deviates from Arrhenius, ...