Design and Optimization of Nano-Composite Hydrogel Biopolymer Electrolytes from Aloe Vera/Sodium Alginate with Yttrium Oxide as Fillers for Electric Double-Layer Capacitor (EDLC) Application

Tee, Yu Xian (2026) Design and Optimization of Nano-Composite Hydrogel Biopolymer Electrolytes from Aloe Vera/Sodium Alginate with Yttrium Oxide as Fillers for Electric Double-Layer Capacitor (EDLC) Application. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

This research investigates the development of a sustainable Aloe vera/sodium alginate hydrogel biopolymer electrolyte (HGBPE) for Electric Double-Layer Capacitor (EDLC) applications, specifically addressing the safety and environmental limitations of conventional liquid systems. The study establishes a two-system optimization framework, highlighting the successful integration of yttrium oxide Y2O3 as a Rare Earth Element (REE) nanofiller to engineer fast ion-conducting pathways. In the first system, the 70wt.% to 30 wt.% of Aloe vera and sodium alginate blend (SA30) achieved a peak ambient ionic conductivity of (8.10 ± 0.15) mS/cm. For the second system, incorporating 0.05wt.% of Y2O3 (YN0.05) further boosted ionic conductivity to (10.05 ± 0.10) mS/cm, attributed to the formation of space-charge regions that provides fast ion-conducting pathway. The EDLC fabricated with this optimized electrolyte and symmetrical carbon-based electrodes achieved a high specific capacitance of 109.58 F/g at a scan rate of 0.002 V/s. Despite gradual performance attenuation over 10,000 continuous cycles, confirming the potential of this safe and biodegradable system as a high-performance alternative for green energy storage architectures