Browsing by Author "Hashmi"

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    Preparation of a Highly Porous Binderless Activated Carbon Monolith from Rubber Wood Sawdust by a Multi-Step Activation Process for Application in Supercapacitors
    (2015-09-09) Taer, Erman; Deraman, Mohamad; Talib; Awitdrus; Hashmi; Umar
    Binderless activated carbon monoliths (ACMs) with high porosity that were prepared from self-adhesive pre-carbonized rubber wood sawdust were studied as electrodes for supercapacitors, focusing on the influence of activation time on the physical and electrochemical properties of the ACMs. The ACMs were activated under a flow of CO2 gas at a rate of 0.5 liters per minute and at a temperature of 900 oC. Activation time varied from 1 to 6 hours and with a multi-step heating profile. The ACM was characterized physically (density, porosity, structure and surface morphology) and electrochemically (specific capacitance, equivalent series resistance, energy and power density). This study found that the combined effects from the length of activation time, binderless property and multi-step heating had the greatest influence on the physical and electrochemical properties of the ACM. The optimum ACM was activated for 5 hours and had a specific capacitance, equivalent series resistance, energy and power density of 138 F g-1, 0.49 Ohm, 2.63 Wh kg-1 and 291 W kg-1, respectively.
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    Preparation of highly porous binderless activated carbon electrodes from fibres of oil palm empty fruit bunches for application in supercapacitors
    (2015-09-07) Farma, Rakhmawati; Deraman, Mohamad; Awitdrus; Taer, Erman; Talib; Basri, Nur Hamizah; Manjunatha; Ishak; Dollah, Besek Nurdiana Mohd; Hashmi
    Fibres from oil palm empty fruit bunches, generated in large quantities by palm oil mills, were processed into self-adhesive carbon grains (SACG). Untreated and KOH-treated SACG were converted without binder into green monolith prior to N2-carbonisation and CO2-activation to produce highly porous binderless carbon monolith electrodes for supercapacitor applications. Characterisation of the pore structure of the electrodes revealed a significant advantage from combining the chemical and physical activation processes. The electrochemical measurements of the supercapacitor cells fabricated using these electrodes, using cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge–discharge techniques consistently found that approximately 3 h of activation time, achieved via a multi-step heating profile, produced electrodes with a high surface area of 1704 m2 g 1 and a total pore volume of 0.889 cm3 g 1, corresponding to high values for the specific capacitance, specific energy and specific power of 150 F g 1, 4.297 Wh kg 1 and 173Wkg 1, respectively