Poly(vinyl alcohol)-Based Phase Inversion Membranes for Sodium-Ion Conducting Solid Polymer Electrolytes

Abstract

Poly (vinyl alcohol) (PVA)-based thin films can be utilized as an ion-conducting polymer electrolyte membrane for battery and supercapacitor when it incorporates a sodium salt such as Na₂SO₄. Hence, we fabricated the PVA/Na₂SO₄ membrane using the phase inversion method, for which ethanol was employed as a nonsolvent. Then we studied the structural, thermal, morphological and electrical properties of the PVA-based membranes using x-ray diffraction (XRD), thermogravimetric analysis (TGA) coupled with differential thermal analysis (DTA), optical microscopy (OM) and electrochemical impedance spectroscopy (EIS). Resultantly, the PVA/Na₂SO₄–based solid polymer electrolyte exhibited the ionic conductivity of ~2.0x10^-7 S/cm. Furthermore, the electrochemical devices with the ITO/PVA(Na₂SO₄)/ITO configuration exhibited the electric double layer capacitance (EDLC) behavior with the energy storage of 9.2 μF/cm² (Na₂SO₄ 0.5M) and 8.1 μF/cm² (Na₂SO₄ 1.0 M) in the potential range of 0.0V to 1.2 V.