Investigation of Mg2+ ion on Structural, Morphological, FTIR, Dielectric and AC Conductivity of PVDF-HFP Based Solid Polymer Electrolytes and Application to Electrochemical Cell

Abstract

In this paper, solid polymer electrolytes comprising of Poly (vinylidene-fluoride-hexafluoropropylene) (PVDF-HFP) polymer and Mg (ClO4)2 salt were prepared by employing the solution casting technique. The fabricated polymer-salt electrolyte membranes are exposed to XRD, FTIR and SEM studies. The real and imaginary part of dielectric permittivity is illustrated with the Cole-Cole plot. Static dielectric constant \({(\epsilon }_{s})\), dynamic dielectric constant \(\left({\epsilon }_{\infty }\right)\), dielectric strength \(({\Delta }\epsilon\)), dielectric loss (tanδ) and relaxation time (τ) are determined using the Cole-Cole plot. The electrochemical properties; cell stability, cell discharge characteristics, dc and ac conductivity are analyzed. Structural studies of XRD peaks are broadened to confirm the amorphous phase of polymer matrix. Morphological studies shows the presence of interlinked micro-pores promote for ease of mobility of Mg2+ ions which attribute to enhance ionic conductivity. The static dielectric constant \({(\epsilon }_{s})\), dynamic dielectric constant \(\left({\epsilon }_{\infty }\right)\), dielectric strength \(({\Delta }\epsilon\)), dielectric loss (tanδ) reach maximum but relaxation time (τ) decreases for an optimal concentration ratio of (100:40) PVDF-HFP: Mg (ClO4)2 that reveals fast hopping of ions from one site of the polymer chain to another. The highest ionic conductivity of 7.73333x 10− 4 Scm− 1 is obtained at room temperature for [PVDF-HFP: Mg(ClO4)2] polymer-salt electrolyte. The cell discharge characteristics of OCV and SCC of Mg/ [PVDF-HFP: Mg(ClO4)2] /I + C cell are found to be 1.8 V and 120 mA respectively The electrochemical stability was observed with a constant voltage of 0.43volt in a positive cycle and 0.4 volts of negative potential which favors an electrochemical membrane for battery applications