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Browsing Other University Publications by Subject "Activated carbon"

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    Capacitance improvement in the presence of fractal graphene: activated carbon composite by improving the electrolyte wettability
    (Postgraduate Institute of Science (PGIS), University of Peradeniya, Peradeniya ,Sri Lanka, 2024-11-01) Dissanayake, Maithri; Kumara, G. R. A.
    Supercapacitors are gaining attention as energy storage devices due to their rapid charge and discharge capabilities, bridging the gap between traditional capacitors and batteries. A significant challenge in optimizing activated carbon-based supercapacitors is the limited wettability of the carbon material by electrolytes, which is crucial for efficient ion transport and charge storage. This study investigated the integration of Fractal Graphene Aggregate (FGA-1) into Activated Carbon (AC) to enhance wettability and supercapacitor performance. Experimental methods involved preparing two test tubes: one with activated carbon alone and the other with a composite of activated carbon and FGA-1. The electrolyte used was a 1M solution of tetraethylammonium tetrafluoroborate dissolved in acetonitrile. The experiment was conducted at room conditions, with the distance travelled by the electrolyte measured using a ruler (least count of 1 mm) and capacitance measured using Metrohm Autolab PGSTAT 128 N. The experiment was repeated five times, and the average distance travelled was recorded. Results indicated that the incorporation of FGA-1 improved the average distance travelled by the electrolyte, leading to a capacitance increase from 1 F for activated carbon alone to 3.96 F for the AC:FGA-1 composite. Quantitative analysis using the Washburn equation revealed that the effective diffusion constant of the electrolyte increased by a factor of four with FGA-1, confirming enhanced wettability. Scanning electron microscope images showed that AC pores and jagged edges were covered with FGA-1, indicating improved wettability due to size differences and the formation of new paths for electrolyte flow. These findings suggest that FGA-1 enhances activated carbon's wetting behaviour, offering the potential for developing more efficient supercapacitor materials and advancing energy storage technologies.
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    Quasi-solid-state supercapacitor with coconut shell-derived activated carbon electrodes and H3PO4/ polyvinyl alcohol gel electrolyte
    (Postgraduate Institute of Science (PGIS), University of Peradeniya, Peradeniya, Sri Lanka, 2024-11-01) Fernando, W. W. S. S. R.; Bandara, T. M. W. J.; Wijayaratne, K. B.; Rajakarunarathne, R. D. M. A. C. B.
    Coconut shells are excellent sources of activated carbon because of their highly porous structure, which gives a larger surface area. However, reports on solid and quasi-solid-state supercapacitors are relatively scarce. More environmentally friendly activated carbon can be produced via the physical activation process, and the physical activation approach is frequently regarded as being better than the chemical approach for deriving carbon from coconut shells. Furthermore, compared to the chemical technique, which might introduce impurities via activating chemicals, the physical method typically yields cleaner and purer activated carbon by reducing the potential for impurities to react with the electrolyte. Here, coconut shell charcoal is carbonized and heated to a high temperature to expose it to activating gases such as steam or carbon dioxide. Supercapacitor electrodes were prepared using activated carbon ink incorporated with 5% polyvinylidene formation of electrodes. This activated carbon ink was coated on graphite sheets, which were used as capacitor current collectors via the drop-casting method. The significance of the study is the use of polyvinyl alcohol (PVA)/H3PO4 based gel polymer electrolyte prepared using the hot press method. This gel polymer electrolyte exhibited the highest ionic conductivity of 46 Ms/cm when 3.5 g of H3PO4 was used with 10 mL of PVA. The specific capacitance of the corresponding assembled quasi-solid-state supercapacitor was 2.29 F/g, which is comparatively lower than that of liquid electrolyte-based supercapacitors. However, the gel electrolyte supercapacitor offers improved stability, minimized electrolyte evaporation, and reduced leakage due to its elevated viscosity and the structural integrity of the gel matrix. Cyclic voltammetric graphs appreciably resembled the behaviour of an electrical double-layer supercapacitor. The quasi-solid-state supercapacitor exhibited power and energy densities of 263.3 W/kg and 7.31 × 10−2 Wh/kg respectively. This preliminary study establishes a basis for further optimization of photo-supercapacitors with stable gel electrolytes.