Proton conducting polymer electrolytes based on KH2PO4 doped PVA

Abstract

Transparent and anhydrous proton conducting polymer electrolytes based on polyvinyl alcohol (PVA)/potassium dihydrogen phosphate (KH2PO4) with different concentrations of KDP (φKDP) were prepared by solution casting technique. Ionic conductivity of the polymer electrolytes, studied by the complex impedance method, increases with increasing temperature as well as phosphate doping-level and then decreases with increasing phosphate (φC>2.5wt%KDP). The maximum ionic conductivity (3.7 × 10−4 S/cm) and minimum activation energy (∼0.25eV) was obtained at 303K for this typical concentration φC. The temperature dependence of ionic conductivity of the prepared polymer electrolytes obeys Arrhenius law. Moreover, the PVA/KDP composite exhibiting high dielectric constante ε′ ∼ 430 (80 times higher compared to pure PVA) near the percolation threshold (φC =2.5wt% KDP) with low dielectric losses (∼0.15) at 1 kHz and room temperature might be suitable for technological applications.