Investigate salts type and concentration on the conductivity of polymer electrolyte

Abstract

Polymer electrolytes compose of {polyethylene oxide (PEO)+ potassium iodide (KI)+iodine (I2)} and {PEO+ rubidium iodide (RbI)+I2} with different weight ratio of salts, and a fixed amount of ethylene carbonate (EC) and propylene carbonate (PC) has prepared by solution casting method. The conductivity and dielectric constant of the gel electrolytes were studied over temperatures range (293-343) K. The conductivity of the electrolytes increases steadily with increased concentration of salts KI and RbI. The higher value of conductivity of (4.7× 10-3 at RT) S.cm-1 for electrolyte contains (KI 50%). Whereas the maximum amount of conductivity of (5.4× 10-3 at RT) S.cm-1 for electrolyte includes (RbI 50%) the ionic conductivity depends on the ionic radii of the migrating species effect on it. As the temperature increase, the number of free ions also increases, thus increases the diffusion of ions through their free volume of the polymer. The dielectric constant decrease at higher frequencies due to the inability of dipoles to align quickly with the change of applied field. The dielectric constant proportional positively with variation temperature causes an increase in the dielectric constant. The higher the value of real dielectric constant (εr), the better is the electrical conductivity.