Preparation and Characterisation of Gel Polymer Electrolyte Containing Sodium Sulfide and Plasticiser

Tan, Guan Ting (2026) Preparation and Characterisation of Gel Polymer Electrolyte Containing Sodium Sulfide and Plasticiser. Final Year Project (Diploma), Tunku Abdul Rahman University of Management and Technology.

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Abstract

This project focuses on the development and analysis of gel polymer electrolytes (GPEs) based on a poly(acrylamide-co-acrylic acid) (PAAm-PAA) polymer matrix, using sodium sulfide (Na₂S) as the salt and propylene carbonate (PC) as the plasticiser. The objective of this study is to investigate the effects of Na₂S molar concentration and PC weight percentage on the ionic conductivity and chemical properties of the prepared GPEs. The study consists of two systems: the first system investigates the effect of varying Na₂S concentration from 0 M to 4 M, while the second system examines the effect of varying PC content from 0 wt.% to 30 wt.%. The GPEs were prepared via aqueous solution mixing followed by gelation, where the polymer was dissolved in distilled water before the addition of Na₂S and PC at the desired compositions. The resulting samples were characterised using Electrochemical Impedance Spectroscopy (EIS) to evaluate ionic conductivity and Fourier Transform Infrared Spectroscopy (FTIR) to analyse their chemical structure. The EIS results showed that the ionic conductivity increased from 0.0327 S·cm⁻¹ at 0 M Na₂S to the highest value of 0.3484 S·cm⁻¹ at 3 M Na₂S, before slightly decreasing at 4 M due to possible ion grouping. In the PC system, the highest conductivity was obtained at 0 wt.% PC with 0.3484 S·cm⁻¹, while increasing PC content reduced the conductivity, with the lowest value of 0.1156 S·cm⁻¹ at 30% PC. FTIR analysis confirmed the presence of important functional groups such as C–O, C–N, C–H, N–H and C=O, showing interactions between the PAAm-PAA, Na₂S and PC. Overall, the results indicate that the GPE containing 3 M Na₂S without additional PC exhibited the highest ionic conductivity in this study