Tailoring of the structural, morphological, electrochemical, and dielectric properties of solid polymer electrolyte

Abstract

A solid polymer electrolyte composed of poly(ethylene oxide) and sodium hexafluorophosphate has been synthesized with a varying fraction of succinonitrile via solution cast technique. Impedance spectroscopy, transference number measurements, and linear sweep voltammetry were used to study the electrochemical properties. The 10\xa0wt.% succinonitrile system exhibited the highest ionic conductivity of ~\u20092\u2009×\u200910−5\xa0S\xa0cm−1 which is two orders of magnitude higher than the pristine polymer salt system. The high ionic transference number (~\u20091) confirms that ion conduction is dominated by ions and displays the voltage stability window of about 4\xa0V. The dielectric permittivity and the relaxation time (\n $$ {\\tau}_{\\upvarepsilon^{\\prime }},\\kern0.5em {\\tau}_{\\mathrm{M}},{\\tau}_{\\mathrm{h}} $$\n ) values corresponding to the segmental motion of the polymer chain varies with the variation of succinonitrile content. The relaxation time and double-layer capacitance are in good agreement with the conductivity. Finally, an ion transport mechanism has been proposed to provide a better understanding of ion migration.