Structural and electrical studies of ultra-sonicated sodium-ion embedded polyvinyl alcohol and polyvinyl pyrrolidone solid polymer blend electrolytes

Solid-state electrolytes are gaining significant attention as promising candidates for next-generation energy storage systems due to their improved safety and stability. In the present study, a sodium iodide (NaI)-doped polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) polymer blend electrolyte was synthesized via the solution casting method. To achieve uniform dispersion of sodium ions and enhance the amorphous phase within the solid polymer blend electrolytes (SPBEs), ultrasonication was employed. Structural and optical analyses confirmed that ultrasonication effectively reduces crystallinity, thereby promoting ion transport. Fourier Transform Infrared (FTIR) spectroscopy revealed strong miscibility and interaction between PVA and PVP. Impedance spectroscopy, particularly the Cole-Cole plot, indicated the presence of double-layer capacitance in the low-frequency region. The maximum ionic conductivity was measured to be 6.96 × 10⁻⁵ S cm⁻¹ for the ultrasonicated PVA/PVP/NaI SPBE. Dielectric studies demonstrated a significant increase in both dielectric constant and dielectric loss at higher frequencies. Furthermore, electric modulus analysis confirmed the non-Debye relaxation behavior of the polymer blend electrolytes.