Browsing by Author "Bandara, T.M.W.J."

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    Agar-Based Gel Polymer Electrolyte with KI and Tetrapropylammonium Iodide Salts for Dye-Sensitized Solar Cell
    (Uva Wellassa University of Sri Lanka, 2020) Nirodha, M.D.; Nishshanke, G.B.M.M.M.; Pitawala, H.M.J.C.; Bandara, T.M.W.J.
    At present, energy consumption is rising predominantly, thus low cost, renewable, and environmentally benign energy resources drag attraction extensively. Although many researches have been done on polymer electrolytes, there is a captivating direction to explore bio-polymer electrolytes in a quasi-solid state. In the present work, a novel gel polymer electrolyte was prepared by a hot press method utilizing tetrapropylammonium iodide (Pr4NI) and potassium iodide (KI) as the binary iodide salt system. Agar bio polymer was combined with the glycerol and formaldehyde solvents to obtain the quasisolid state polymer plasticizer matrix. The KI and tetrapropylammonium iodide weight ratio in the electrolyte was altered while keeping the masses of other ingredients constant to optimize the solar cell performance. Gel electrolytes displayed quite high viscosity while retaining a gel-like consistency at ambient temperature. Fourier transform infrared spectroscopy results indicate a peak heightens gradually at 750 cm-1 with increasing Pr4NI salt amount. Electrical impedance spectroscopy was used to deduce the ionic conductivity of each electrolyte. The highest ionic conductivity of 3.39 mS cm−1 is achieved by the electrolyte sample only with KI at 26 °C as the contribution for ionic conductivity from small K+ cation is higher compared to the bulky Pr4N+ cation. The uniform shape of cyclic voltammetry curves of each electrolyte during 12 consecutive cycles with 5 min time steps revealed the stability of electrolytes. A dye-sensitized solar cell was assembled by inserting the highest conducting gel polymer electrolyte having Glass/FTO/TiO2/N719-Dye/GPE/Pt/Glass configuration. The dye-sensitized solar cell fabricated with the highest conducting electrolyte displayed an efficiency of 0.36% with JSC of 1.31 mA cm−2 , VOC of 0.4 V, and fill factor of 0.68. Keywords: Biopolymer, Gel polymer electrolyte, Agar, Tetrapropylammonium iodide, Dye-sensitized solar cell
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    Facile Way of Preparing Activated Carbon (AC) Electrodes from the Local Jack-Wood for Supercapacitors
    (Uva Wellassa University of Sri Lanka, 2020) Thennakoon, T.M.A.A.B.; Bandara, L.R.A.K.; Bandara, T.M.W.J.
    Supercapacitors (SCs) are used as high power density energy storage devices in many applications. Based on the charge-discharge mechanism, SCs are divided into three main classes; electrochemical double-layer capacitors (EDLCs), pseudo-capacitors, and hybrid capacitors. High specific surface area electrodes need to be developed using chemically and physically stable materials to prepare high energy density EDLCs having a long cycle life. By increasing the porosity of electrodes, the effective surface area of the interface can be enhanced. This study introduces a facile way of preparing activated carbon (AC) electrodes starting from the local Jack-wood. Besides, in this research, a novel low-cost SC is prepared using AC electrodes fabricated from Jack wood charcoal without using a binder or additive. The activation is done using a NaOH solution. AC electrodes of the size,1 cm × 2 cm × 0.5 cm, were used for SCs preparation. Platinum (Pt) electrodes were used as current collectors, and for this purpose, Pt was coated on one side of the carbon electrodes. The EDLCs were assembled using activated carbon electrodes and 5 M potassium hydroxide (KOH) electrolyte. For this purpose, polytetrafluoroethylene (PTFE) membrane filter paper separator having 0.2-µm pore size was sandwiched between two AC electrodes. To characterize EDLCs assembled, complex impedance, charge-discharge measurements, and cyclic voltammograms (CV) were measured with the help of PGSTAT128N – Metrohm Auto-Lab setup. The high chemical stability of the EDLCswithin, the charge-discharge window +0.5 V to -0.5 V, can be inferred from CV. The highest gravimetric capacitances of the SCs were 71.89 F g-1 . Power density of 342.12 W kg-1 and the energy density of 0.27 Wh kg-1 were exhibited by the EDLC prepared using Jack-wood AC electrodes. The prepared low-cost Supercapacitor is suitable for many applications that need power for a short period. Keywords: Activated carbon, Electrical double layer, Gravimetric capacitance Jack-wood, and Supercapacitor
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    Polyacrylonitrile Based Gel Polymer Electrolyte for Rechargeable Magnesium Ion Batteries
    (Uva Wellassa University of Sri Lanka, 2020) Dias, N.A.T.H.; Pitawala, H.M.J.C.; Ratnasekera, J.L.; Bandara, T.M.W.J.; Nayanakanthi, M.D.M.
    The demand for energy storage devices has highly increased with the increment of the demand for electronic portable devices and electric vehicles. Therefore, developing rechargeable batteries has received the most attention. Among the components of a rechargeable battery, electrolyte is highly concerned as it is the medium for the transfer of charges between the pair of electrodes. Developing gel polymer electrolytes is mostly explored due to its favourable performances and minimum drawbacks compared to liquid electrolytes and solid electrolytes. In this research polyacrylonitrile based gel polymer electrolyte for magnesium ion batteries was prepared and characterized to investigate its physicochemical properties. Preparation of gel polymer electrolytes was carried out by a common solution casting technique using dimethyl sulfoxide as the solvent, magnesium trifluoromethanesulphonate as the salt and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide as the ionic liquid. Impedance spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and Differential scanning calorimetry was performed to analyse the prepared electrolyte samples. The maximum room temperature ionic conductivity of 2.33×10-3 S cm-1 and 3.33×10-3 S cm-1 were obtained for the sample before and after the addition of ionic liquid respectively. Considerable indications for the polymer-solvent, polymer-salt, and polymer-salt-ionic liquid interactions were investigated by analysing Fourier transform infrared spectroscopy. Although the crystallinity has increased with the addition of salt due to the formation of ion pairs and aggregates, the effect has been preserved with the addition of ionic liquid. The glass transition temperature has also increased from 80 0C to 104 0C after the coordination of polyacrylonitrile with magnesium trifluoromethanesulphonate, however, it is reduced to 102 0C after the addition of ionic liquid. Keywords: Gel polymer electrolyte, Polyacrylonitrile, Magnesium trifluoromethanesulphonate, Ionic liquid, Ionic conductivity