Correlation between Ion Transport and Structural Heterogeneity in Triazole-Based Polymerized Ionic Liquids

Monday, 10 October 2022
J. Jeddi (University of Tennessee, Knoxville), J. Sangoro (University of Tennessee Knoxville), J. Niskanen, and B. H. Lessard (University of Ottawa)
In this study, the relationship between chemical structure, nanoscale organization, and ion transport in 1,2,3-triazolium polymerized ionic liquids (PILs) was investigated by wide-angle X-ray scattering (WAXS) and broadband dielectric spectroscopy (BDS). Analyzing the WAXS and BDS results indicated that mobile ion types and chemical structure of the pendant groups controlled structural heterogeneity and ion conduction of the PILs below Tg. The normalized heterogeneity length extracted from WAXS data was used to correlate the structural heterogeneity and ion conduction activation energy. For the polycation samples, larger TFSI mobile anion results in a higher packed structure than small Cl while in the polyanion samples inverse trend was observed. The calculated activation energy of the dc conductivity below Tg is quantitatively correlated to the structural heterogeneity obtained from nano structure analysis using WAXS. This suggested increasing the spatial heterogeneity of the PILs results in the reduction of the activation energy of long-range ion motions. These results highlight the role of spatial heterogeneity in designing efficient polymerized ionic liquids