Polyethylene Oxide Incorporated Ammonium Iodide Doped With Ionic Liquid Trihexyl (Tetradecy) Phosphonium Dicyanamide-Based Polymer Electrolyte for Dual Energy Storage Devices

Cation phosphonium-based ionic liquids (PBILs) have recently gained attention since the 2000s due to their thermal stability and low viscosity for better ionic conduction in electrochemical devices. This paper introduces a new low-viscosity phosphonium-based ionic liquids (PBILs)—trihexyl (tetradecy) phosphonium dicyanamide—infused in polyethylene oxide: ammonium iodide (NH₄I) complex polymer electrolyte. The electrochemical impedance spectroscopy studies indicate that the ionic conductivity reaches 2.03 × 10⁻⁴ S/cm at 6 wt.% PBILs at ambient temperature. The PBILs-doped polymer electrolyte is predominantly ionic confirm by ionic transference numbers (t_ion) calculation. Also the electrochemical stability window was found to be 3.2 V suitable for energy storage devices. The highest achieve ionic conductivity PBILs-doped polymer electrolyte sandwich between the electrodes for dual energy devices like electric double layer capacitors (EDLCs) and dye-sensitized solar cells (DSSCs). This study shows improvements in ionic conduction, double-layer stability, and light-harvesting efficiency, resulting in higher energy density and power density in EDLCs and better photovoltaic performance in DSSCs. These findings highlight the versatility and efficacy of phosphonium-based ionic liquid-doped polymer electrolytes for advanced energy storage and conversion applications.