Browsing by Author "Sumathipala, H. H."

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Comparison study of mechanical and chemical properties of ancient and modern clay pots
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Madhuwanthi, H. M. L. U.; Katugampola, M.; Jayathilaka, K. M. D. C.; Sumathipala, H. H.
In this study, the ancient clay pottery samples from archaeological site Devalapola, Minuwangoda, Sri Lanka (3000 years, radiocarbon age) which were found by the Department of Archaeology, University of Kelaniya, were collected and compared their physical properties with modern clay pottery samples. Also to analyze the mineralogical components and the compositions, the Scanning Electron Microscopy (SEM) coupled with the Energy Dispersive X-Ray spectroscopy (EDX) analysis were performed on the both ancient and modern clay pot samples on both side and top surfaces of them. The firing clay objects is an irreversible process, which produces ceramic materials characterized by new chemical-mineralogical composition and different physical and microstructural features. Physical properties of the shards such as pottery density and water absorption capacity were analyzed. There was no significant difference in the pottery density. The values for the water absorption of the ancient clay pot samples have a wider range than the modern clay pot samples. According to the SEM results, the grain sizes of the modern clay pot samples are comparatively larger than the ancient clay pot samples. The grain sizes of the ceramic indicate the open porosity of the matrix. Based on the SEM-EDX results, SiO2 and Al2O3 were the major components of the both ancient and modern clay pot samples while CaCO3, MgO, MAD-10-Feldspar, CaSO3, Ti, and Fe are present in trace amounts. Further albite, FeS2 and KCl were only present in the modern clay pot samples. By analyzing the EDX results it can be concluded that when the production of the ancient potteries was happening, the furnace atmosphere was filled with more CO2 and the firing temperature of the ancient clay pot samples at the production was around 850 - 9000C.
Ionic conductivity of novel solid polymer electrolyte based on polyethylene oxide (PEO) and magnesium pyrophosphate (Mg2P2O7)
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Lakshan, K. L. A. C.; Sumathipala, H. H.; Wijesundara, L. B. D. R. P.
Lithium-ion batteries were hailed as a breakthrough solution for energy storage, revolutionizing portable electronics, electric vehicles, and other applications. However, as their implementation expanded, certain drawbacks came to light. Issues such as limited energy density, safety concerns, and the scarcity and high cost of lithium resources highlighted the need for a replacement. Researchers turned their attention to alternative materials, with sodium being a promising candidate due to its abundance. However, its high reactivity posed significant challenges. The search for a viable alternative led scientists to explore magnesium-based electrolytes. Lithium and magnesium are almost similar in ionic radii, presenting an exciting opportunity for further research. In this Investigation, the focus was on synthesizing and characterizing a novel magnesium ionbased solid polymer electrolyte. Polyethene oxide (PEO) was chosen as the polymer host, and magnesium pyrophosphate (Mg2P2O7) as the dopant salt. By varying the amount of salt while keeping the same amount of PEO, five different types of electrolytes were made: PEO5Mg2P2O7, PEO10Mg2P2O7, PEO15Mg2P2O7, PEO20Mg2P2O7, and PEO25Mg2P2O7. The hot-pressed technique was used to fabricate the solid polymer electrolytes, and the resulting materials were characterized in the frequency range of 1Hz to 1 MHz using the Gamry framework version 6.11. Arrhenius plots were derived from Nyquist plots to study the conductivity variation with temperature. The temperature range for the study spanned from 25°C to 100°C. The characterization results revealed that among the different electrolyte samples, PEO10Mg2P2O7 demonstrated the highest electrical conductivity of 5.0×10-6 Scm-1 at 50°C. This temperature was selected since the melting point of PEO is 64 °C. This value of conductivity is comparatively lower than most existing magnesium ion-based solid polymer electrolytes. The results from this study pave the way for further investigations and improvements. Incorporating fillers could enhance the conductivity of the electrolyte material and improve its overall performance. Such advancements may yield even more promising results, making magnesium-based solid polymer electrolytes viable candidates for solid-state batteries. Alternatively, a gel polymer might give a more promising result than a solid polymer.
A new Sodium based electrolyte – PEO10NaBrO3
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Sankalpa, H. A. C.; Sumathipala, H. H.; Wijesundera, R. P.
The necessity of new and environmental friendly rechargeable batteries is increasing day by day due to the current technology development and power demand. Hence, efficient and low-cost new electrolyte materials have to be discovered and more attention has to be placed on searching environmental friendly, non-toxic materials. Sodium salts are the most potential materials due to their abundance and low-cost. This study focuses to investigate the electrical conductivity of a sodium-based electrolyte which can be used in solid state batteries. Composite of Poly Ethylene Oxide (PEO) and Sodium Bromate (NaBrO3) are used as the electrolyte and samples were prepared by the hot-pressed method. Electrical conductivity measurements were carried out for samples prepared by varying the molar ratio of PEO and NaBrO3. According to the results, PEO-NaBrO3 has the potential to be developed as a sodium-based electrolyte. Experimental results revealed that the highest electrical conductivity is being produced for PEO10NaBrO3 samples. Best sample exhibited 3.44×10-5 S cm-1 conductivity in room temperature (30 °C) and 2.14×10-2 S cm-1 conductivity at 100 °C. These results show the evidence of potential usage of PEO10NaBrO3 as an electrolyte in solid state Batteries. However, further investigations should be carried out to investigate the contribution of the Sodium ions for the observed conductivity