| Summary: | The central focus of this paper revolves around investigating biopolymer electrolyte films characterized by exceptional ionic conductivity, a prerequisite for the practical implementation of sodium-ion batteries. This study successfully prepared the agarose-based biopolymer electrolyte using the solution casting method. The effects of adding various weight percentages (0, 10, 20, 30 and 40 wt.%) of sodium nitrate salt (NaNO3) to agarose-based biopolymer electrolytes were characterized. Electrochemical Impedance Spectroscopy (EIS) was adapted to analyze the conductivity and dielectric relaxation phenomena of the agarose-NaNO3 complex. The conductivity of agarose-based biopolymer electrolytes increases with the increasing salt concentration. The increase in ionic conductivity is due to the increase in the number of charge carriers and the mobility of the sodium ions. The highest room temperature conductivity was 3.44×10-5 S⋅cm-1 for the agarose-NaNO3 biopolymer electrolytes containing 30 wt.% sodium nitrate. X-ray diffractometer (XRD) spectroscopy was employed to investigate the crystallinity of the agarose-based biopolymer electrolyte. It was confirmed that the agarose-based biopolymer with 30 wt.% of sodium nitrate is the most amorphous compared to the others, as it has the largest full width at half maximum (FWHM) and the smallest crystallite size. This indicated that the amorphousness of the biopolymer electrolyte boosts the Na+ ions' mobility, increasing the ionic conductivity of the samples. © 2024, Malaysian Society of Analytical Sciences. All rights reserved.
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