Fabrication and characterization of polymer electrolyte based on PAN with NaSCN for solid-state sodium-ion batteries

Sodium-ion batteries (SIBs) are considered next-generation energy storage devices due to their abundant availability and cost-effectiveness. SIBs serve as a promising alternative to lithium-ion batteries (LIBs). In this study, an effort is made to develop sodium-ion conducting electrolytes using polyacrylonitrile (PAN) as the host polymer and sodium thiocyanate (NaSCN) by the solution casting technique. The prepared sodium-ion conducting membranes are characterized using X-ray diffraction analysis (XRD) to examine their amorphous/crystalline nature. The complex formation between the salt and polymer is confirmed by Fourier transform infrared spectroscopy (FTIR). The sodium-ion conductivity of the prepared membranes is measured using the AC impedance technique. The solid polymer membrane composed of 55 wt.% PAN/45 wt.% NaSCN exhibits a high sodium-ion conductivity of 8.8 × 10⁻³ S/cm. This polymer membrane exhibits a low glass transition temperature (T_g). Linear sweep voltammetry (LSV) and cyclic voltammetry (CV) studies are performed for high-conducting membrane to evaluate their electrochemical stability. A primary solid-state sodium-ion battery is constructed using the high sodium-ion conducting polymer electrolyte which exhibits an open circuit voltage of 2.52 V. When a load of 100 kΩ is connected across the battery, a current of 21 µA is drawn. The performance of the primary solid-state SIB is evaluated under various loads.