Palm-based polyurethane electrolyte was prepared via prepolymerization method between palm kernel oil polyol (PKO-p) and 2,4′-diphenylmethane diisocyanate (MDI) in acetone at room temperature with the presence of lithium trifluoromethanesulfonate (LiCF3SO3). The effect of varying the concentration of LiCF3SO3salt on the ionic conductivity, chemical interaction, and structural and morphological properties of the polyurethane solid polymer electrolyte was investigated. The produced film was analyzed using electrochemical impedance spectroscopy (EIS), attenuated total reflection Fourier transform infrared (ATR-FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The EIS result showed that the highest ionic conductivity was at 30 wt% LiCF3SO3with a value of 1.6 × 10−5 S·cm−1. Infrared analysis 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) of the polyurethane forming polymer-salt complexes. The XRD result proved that LiCF3SO3salt completely dissociates within the polyurethane film as no crystalline peaks of LiCF3SO3were observed. The morphological study revealed that the films prepared have a good homogeneity and compatibility as no phase separation occurred.

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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-LiCF3SO3complexes 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 1.55×10-5S cm-1at 30 wt.% of LiCF3SO3at 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).