Ionic liquid based NCPBE membranes for electrochemical capacitor applications: Structural, thermal and electrical transport properties

The current study focuses on the preparation and characterisation of imidazolium ionic liquid based plasticized nano-composite polymer blend electrolytes (NCPBEs). Semi-crystalline nature of the synthesized samples was observed using XRD analysis. ATR-FTIR results demonstrate the interaction among the carbonyl (CO) and hydroxyl (O-H) groups of polymers with ionic liquid (IL) and salt, NaI. Furthermore, thermo-gravimetric analysis (TGA) indicates multi-step decomposition process. Ion transport mechanism has been analysed using temperature dependent conductivity analysis, ac conductivity analysis and dielectric properties study. The sample containing 25 wt% IL i.e. NCPBE-25 has the ionic conductivity similar to 9.30 x 10(-4) Scm(-1) with the optimum vale of charge carrier density, mobility, and ion diffusivity at 30(o)C. Ions are principal charge carriers in the present electrolytes. The sample NCPBE-25 has the electro-chemical stability window -3.6 to 1.5 V at room temperature. The fabricated electro-chemical capacitor has the specific capacitance, energy density and power density 363.27 Fg(-1), 50.45 Whkg(-1) and 18.16 kW/kg, respectively at the scan rate 5 mV/s.