Impedance spectroscopy of carbon nanotube/solid polymer electrolyte composites

New composite polymer electrolytes (CPE) have been prepared by a solution-casting technique, using polyethylene oxide, lithium hexafluorate (LiPF6) as the doping salt, ethylene carbonate (EC) as the plasticizer and amorphous carbon nanotubes (alpha CNTs) as the filler. The crystallinity and ionic conductivity of the CPE are examined. Differential scanning calorimetry shows a decrease in melting temperature and crystallinity upon the addition of LiPF6, EC and alpha CNTs to the polymer electrolyte system. The addition of salt increases the conductivity up to 10(-5) S cm(-1). The incorporation of EC and alpha CNTs into the salted polymer shows a significant conductivity increase of 10(-4) and 10(-3) S cm(-1). The complexation process is examined using Fourier transform infrared spectroscopy. The Vogel-Tamman-Fulcher (VTF) plots suggest that the temperature dependence of conductivity is a thermally activated process. (C) 2011 Elsevier Ltd. All rights reserved.