Browsing by Author "Aziz"
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Item Effects of Activation Time on the Performance of Supercapacitor Binderless Activated Carbon Electrodes Derived from Fibers of Oil Palm Empty Fruit Bunches(2015-09-07) Ishak; Deraman, Mohamad; Dollah, Besek Nurdiana Mohd; Othman; Omar, Ramli; Basri, Nur Hamizah; Nor, Najah Syahirah Mohd; Taer, Erman; Awitdrus; Farma, Rakhmawati; AzizGreen monoliths (GMs) with different composition, labelled as GM1, GM2 and GM3, were prepared from self-adhesive carbon grains (SACG) produced from fibers of oil palm empty fruit bunches, SACG treated with 0.4 M H2SO4 and mixtures of SACG and carbon nanotubes (5 wt.%) treated with 0.4 M H2SO4, respectively. Each GMs was carbonized and then activated with holding time of 1 h and 2 h, respectively, to produce their respective activated carbon monoliths (ACMs). These ACMs were used as electrodes to fabricate supercapacitor cells using H2SO4 electrolytes, Teflon separator and stainless steel 316L current collector. The porosity of the ACMs, examined by nitrogen adsorption-desorption isotherm method were found affected after prolonging the activation time. From the electrochemical characterization of the ACMs electrodes using galvanic charge-discharge methods, it was found that supercapacitor cells fabricated using the ACMs produced by longer activation time (2 h) showed better performance, which had higher specific capacitance (113 F/g), specific power (159 W/kg) and specific energy (3.35 W h/kg), compared to the cells using ACMs produced by shorter activation time (1 h).Item Supercapacitors using binderless composite monolith electrodes from carbon nanotubes and pre-carbonized biomass residues(2015-09-10) Basri, Nur Hamizah; Deraman, Mohamad; Kanwal; Talib; Manjunatha; Aziz; Farma, RakhmawatiBinderless composite monolith (BCM) electrodes prepared from carbon nanotubes (CNTs) and self-adhesive carbon grains (SACGs) were used in a symmetrical supercapacitor. The SACGs were prepared from fibers of oil palm empty fruit bunches (EFBs) from oil palm tree (Elaeis guineensis), Heliotropium dasycarpum (H. dasycarpum) and Guaiacum officinale (G. officinale). For each biomass, the BCMs were prepared by the carbonization and activation of green monoliths (GMs) containing SACGs treated with KOH and a mixture of SACGs and CNTs treated with KOH. Thermal decomposition behavior of all SACGs was found to be slightly different because of the difference in their compositions. In addition, BCMs from H. dasycarpum and G. officinale were found to have SiO2. The BET surface areas were 1656, 1031 and 532 m2 g 1 for the BCMs from EFB, H. dasycarpum and G. officinale, respectively, and these values decreased by 40, 50 and 31% upon CNTs addition. Consequently, the specific capacitance decreased from w124 to w104 and w49 F g 1 to w111, w87 and w31 F g 1, respectively. However, addition of CNTs reduced the equivalent series resistance (ESR) by a factor of 83.9 (EFB), 90.6 (H. dasycarpum) and 38.8 (G. officinale) %. It was also found that CNTs addition contributed to improving the decay of Csp with increasing scan rate if the electrode surface area was sufficiently high.