Unveiling Ionic Conductivity and Ion Transport Properties in Polyvinyl Alcohol-Based Gel Polymer Electrolytes with Quaternary Ammonium Iodide

To study the behavior of structural dynamics, ionic conductivity and ion transport properties, the gel polymer electrolytes (GPEs) was developed using polyvinyl alcohol in combination with potassium iodide, dimethyl sulfoxide, ethylene carbonate, propylene carbonate and tetra-N-propylammonium iodide (C12H28IN), The GPEs were synthesized via a solution mixing technique, systematically varying the tetra-N-propylammonium iodide concentration to optimize ionic transport properties. The gel polymer electrolytes (GPEs) preparation was initially dissolving the potassium iodide and tetra-N-propylammonium iodide in a measured combination of ethylene carbonate, propylene carbonate, and dimethyl sulfoxide within a glass container. Subsequently, polyvinyl alcohol (PVA) was introduced into the salt solution and continuously stirred at 100°C until a uniform mixture was formed. The solution was then allowed to cool to 30°C and resulting GPE exhibited a gel-like consistency. Electrochemical impedance spectroscopy (EIS) was employed to evaluate ionic conductivity, dielectric behavior, and ion transport properties at the temperature of 25°C. X-ray diffraction (XRD) was utilized to investigate the structure of the gel polymer electrolyte. Fourier-transform infrared (FTIR) spectroscopy was applied to describe the structural interactions between salts and polymer in the GPEs. Notably, the gel polymer electrolytes containing 30 wt.% tetra-N-propylammonium iodides exhibited a remarkable ionic conductivity of approximately 9.70 mS cm−1 at the temperature of 25°C.