Supramolecular functionalities influence the thermal properties, interactions and conductivity behavior of poly(ethylene glycol)/LiAsF6 blends

Abstract

In this study, we tethered terminal uracil groups onto short-chain poly(ethylene glycol) (PEG) to form the polymers, uracil (U)-PEG and U-PEG-U. Through AC impedance measurements, we found that the conductivities of these polymers increased upon increasing the content of the lithium salt, LiAsF6, until the Li-to-PEG ratio reached 1:4, with the conductivities of the LiAsF6/U-PEG blends being greater than those of the LiAsF6/U-PEG-U blends. The ionic conductivity of the LiAsF6/U-PEG system reached as high as 7.81 × 10-4 S/cm at 30°C. Differentialscanning calorimetry, wide-angle X-ray scattering, 7Li nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy revealed that the presence of the uracil groups in thesolid state electrolytes had a critical role in tuning the glass transitiontemperatures and facilitating the transferof Li+ ions. © 2013 by the authors; licensee MDPI, Basel, Switzerland.