Effect of addition of 1-butyl-3-methylimidazolium thiocyanate on conductivity of Na-containing polymer electrolyte

Research in the environmentally friendly energy field has grown rapidly due to severe problems such as global warming and climate change. Sodium-ion technology is one of the most promising alternatives to lithium-ion batteries. Use of ionic liquids containing thiocyanate anion has been considered because of their low cost, low viscosity, and nonhazardous nature. In this work, polyethylene oxide (PEO)–sodium perchlorate (NaClO₄) samples containing different amounts of 1-butyl-3-methylimidazolium thiocyanate ionic liquid were prepared by a solution casting method. Addition of the ionic liquid to the PEO–NaClO₄ electrolyte further increased the ionic conductivity. The electrolyte containing 30 wt% ionic liquid exhibited the maximum ionic conductivity of ~5.0 × 10⁻⁴ S/cm at room temperature. Fourier-transform infrared (FT-IR) spectroscopy revealed the interaction between the polymer chain and salt ion complexes for various sodium salt contents. Differential scanning calorimetry (DSC) demonstrated that the crystallinity was reduced by addition of 1-butyl-3-methylimidazolium thiocyanate ionic liquid.