Electrical conductivity and dielectric relaxation behaviour of PEO/PVdF-based solid polymer blend electrolytes for zinc battery applications

A series of ion-conducting poly (ethylene oxide)/poly(vinylidene fluoride) [PEO/PVdF]-based solid polymer blend electrolytes derived from the addition of varying amounts of zinc trifluoromethane sulfonate (which is also known as zinc triflate), [Zn(CF3SO3)2] as dopant salt were synthesized in the form of films by solution-casting method. Accordingly, freshly prepared specimens of [90 wt% PEO/10 wt% PVdF + x wt% Zn(CF3SO3)2, where x = 3 to 18 wt% in steps of 3 wt%] were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and impedance analysis techniques. The room temperature XRD patterns tend to confirm the formation of an amorphous phase obtained by reducing the crystallinity of the host polymer blend matrix [90 wt% PEO/10 wt% PVdF] as a result of addition of 15 wt% zinc triflate salt. The relevant SEM images of this particular polymer blend electrolyte specimen exhibit a smooth and porous structure when compared to that of the host polymer blend [90 wt% PEO/10 wt% PVdF]. Remarkably, the highest ionic conductivity realized in the case of the typical polymer system [90 wt% PEO/10 wt% PVdF + 15 wt% Zn(CF3SO3)2] is found to be 2.5 × 10−5 S cm−1 at room temperature. The occurrence of ion dynamics and dielectric relaxation behaviour in the chosen system has been analysed in a detailed fashion at room temperature using frequency response impedance formalisms involving electric modulus and dielectric permittivity features.