Characterisations of Palm-Based Polyurethane Solid Polymer Electrolyte

Abstract

Palm kernel oil based polyurethane (PU) electrolyte was prepared via prepolymerization method. The PU films was synthesized at 200/200 and 75/121 for PU1 and PU4 respectively according to the ratio of palm kernel oil polyol (PKO-p) with polyethylene glycol (PEG) as the chain extender to 2,4-methylene diphenyl diisocyanate (MDI). After that, lithium trifluoromethanesulfonate (LiCF3SO3) salt as the charge carrier was added to the system with different percentage at room temperature. The palm-based polymer electrolyte was casted onto teflon plate via solution casting technique and later was characterised by electrochemical impedance spectroscopy (EIS) to obtain ionic conductivity. The presence of PU-LiCF3SO3 complexes were observed by attenuated total reflection fourier transform infrared (ATR-FTIR) spectroscopy. Differential scanning calorimeter (DSC) was used to study the thermal property of the PU electrolyte. The highest conductivity achieved was 1.55×10-5 S cm-1 at 30 wt.% of LiCF3SO3 at room temperature. Infrared analyses showed the interaction between lithium ions and amine group (-N-H) at (3600-3100 cm-1), carbonyl group (-C=O) at (1750-1650 cm-1) and ether group (-C-O-C-) at (1150-1000 cm-1).