Effect of the gel polymer electrolyte conductivity on the performance of Zn rechargeable cells

Gel polymer electrolytes (GPEs) have been extensively considered for various applications such as primary and rechargeable cells, super capacitors and electrochromic devices. Various strategies have been adopted to enhance their properties so as to develop efficient and effective devices. One such method is to increase the ionic conductivity of the electrolyte. In this study, attempts were made to study the variation of ionic conductivity with salt concentration of a GPE and to evaluate the dependence of performance on conductivity in a rechargeable cell. The composition was optimized by varying the salt concentration. The highest room temperature conductivity of 4.46×10 -3 Scm -1 was obtained with the composition 50 PVdF : 100 EC : 100 PC : 80 ZnTf (by weight). The maximum ionic transference number was also obtained with this composition and it was 0.97. Four different cells were fabricated with four different salt concentrations and the best performance was observed with the cell having the GPE of the highest conductivity. This clearly proves that performance of the device depends on the conductivity of the electrolyte.