SWL-Mathematics and Natural Sciences

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Binderless Composite Electrode Monolith from Carbon Nanotube and Biomass Carbon Activated by H2SO4 and CO2 Gas for Supercapacitor
(2015-09-07) Deraman, Mohamad; Ishak; Farma, Rakhmawati; Awitdrus; Taer, Erman; Talib; Omar, Ramli
Binderless composite electrodes in the monolithic form prepared from carbon nanotubes (CNTs) and self‐adhesive carbon grains (SACG) from fibers of oil palm empty fruit bunch were studied as an electrode in a supercapacitor. The green monoliths (GMs) were prepared from three different types of precursors, SACG, SACG treated with 0.4 Molar H2SO4 and mixture of SACG and 5% CNTs (by weight) treated with 0.4 Molar H2SO4, respectively. These GMs were carbonized at 600 °C in N2 gas environment and activated by CO2 gas at 800 °C for 1 hour to produce activated carbon monoliths (ACMs). The properties of the ACMs (density, porosity, microstructure, structure and electrical conductivity) were found affected by CNTs addition and acid treatment. The acid treatment did not improve the electrochemical behavior of the ACMs used as electrodes (specific capacitance, specific energy and specific power of the supercapacitor) in the supercapacitor cells but CNTs addition improves the equivalent series resistance of the cell.
Binderless Composite Electrode Monolith from Carbon Nanotube and Biomass Carbon Activated by KOH and CO2 Gas for Supercapacitor
(2015-09-07) Farma, Rakhmawati; Deraman, Mohamad; Omar, Ramli; Awitdrus; Ishak; Taer, Erman; Talib
This paper presents a method to improve the performance of supercapacitors fabricated using binderless composite electrode monolith (BCMs) from self‐adhesive carbon grains (SACG) of fibers from oil palm empty fruit bunches. The BCMs were prepared from green monoliths (GMs) contain SACG, SACG treated with KOH (5 % by weight) and SACG mixed with carbon nanotubes (CNTs) (5% by weight) and KOH (5 % by weight), respectively. These GMs were carbonized at 800 °C under N2 environment and activated by CO2 gas at 800 °C for 1 hour. It was found that addition of KOH and CNTs produced BCMs with higher specific capacitance and smaller internal resistance, respectively. It was also found that supercapacitor cells using these BCMs as electrodes exhibited a better specific energy and specific power. The physical properties of BCMs (density, electrical conductivity, porosity, interlayer spacing, crystallite dimension and microstructure) were affected by the addition of KOH and CNTs.
Effect of carbonization temperature on the physical and electrochemical properties of supercapacitor electrode from fibers of oil palm empty fruit bunches
(2015-09-07) Ishak; Deraman, Mohamad; Talib; Basri, Nur Hamizah; Awitdrus; Farma, Rakhmawati; Taer, Erman; Omar, Ramli; Dollah, Besek Nurdiana Mohd
Self-adhesive carbon grains (SACG) was prepared from fibers of oil palm empty fruit bunches. The SACG green monoliths were carbonized in N2 environment at 400, 500, 600 and 700°C to produce carbon monoliths labeled as CM1, CM2, CM3 and CM4 respectively. The CMs were activated in CO2 surrounding at 800°C for 1 hour to produce activated carbon monolith electrodes (ACM1, ACM2, ACM3 and ACM4). The physical properties of the CMs and ACMs were investigated using X-ray diffraction, field emission scanning electron microscopy (FESEM) and N2 adsorption-desorption isotherm techniques. ACMs were used as electrode to fabricate symmetry supercapacitor cells and the cells’ performances were investigated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) standard techniques. In this paper we report the physical and electrochemical properties of the ACM electrodes by analyzing the influence of the carbonization temperature on these properties
Effect of Compression Pressure on the Physical and Electrochemical Properties of Activated Carbon Monoliths Electrodes for Supercapacitor Application
(2015-08-18) Awitdrus; Deraman; Talib; Farma, Rakhmawati; Omar; Ishak; Basri; Dolah
Green Monoliths (GMs) of self-adhesive carbon grain from fibers of oil palm empty fruit bunches were prepared by compression pressure at 1.43 × 107, 1.91 × 107 and 2.39 × 107 kg/m2, respectively. Activated carbon monoliths ACM-A, ACM-B and ACM-C prepared by CO2 activation from these GMs, respectively, were used as electrodes in supercapacitor cells which employed stainless steel 316L current collector and H2SO4 electrolyte. Evaluation of the electrochemical properties showed that ACM-A, ACM-B and ACM-C cells had specific capacitance of 30, 9 and 5 F/g, total ESR of 3.21, 4.95 and 7.33 Ω, specific power (maximum) of 173.41, 107.58 and 33.82 W/kg, and specific energy (maximum) of 0.67, 0.15 and 0.09 Wh/kg. These properties are directly associated with the surface area of the ACMs, i.e. 419, 336 and 302 m2/g for the ACM-A, ACM-B and ACM-C, respectively, indicating a direct effect of compression pressure on the physical and electrochemical properties of ACMs electrodes.
Effect of electrolyte concentration on performance of supercapacitor carbon electrode from fibers of oil palm empty fruit bunches
(2015-09-07) Farma, Rakhmawati; Deraman, Mohamad; Talib; Awitdrus; Omar, Ramli; Ishak; Taer, Erman; Basri, Nur Hamizah; Dollah, Besek Nurdiana Mohd
Fibers of oil palm empty fruit bunches were used to produce self-adhesive carbon grains (SACG). The SACG green monoliths were carbonized in N2 environment at 800°C to produce carbon monoliths (CM) and the CM was CO2 activated at 800°C for 4 hour to produce activated carbon monolith electrodes (ACM). The physical properties of the CMs and ACMs were investigated using X-ray diffraction, field emission scanning electron microscopy and nitrogen adsorption-desorption. ACMs were used as electrode to fabricate symmetry supercapacitor cells and the cells which used H2SO4 electrolyte at 0.5, 1.0 and 1.5 M were investigated using electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge-discharge standard techniques. In this paper we report the physical properties of the ACM electrodes and the effect of electrolyte concentration on the electrochemical properties the ACM electrodes
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; Aziz
Green 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).
Electrical Conductivity Of Carbon Pellets Prepared From Mixtures Of Pyropolymers From Oil Palm Bunches and Petroleum Green Coke
(2015-09-07) Deraman, Mohamad; Awitdrus; Talib; Omar, Ramli; Jumali; Ishak; Saad; Taer, Erman; Saman; Farma, Rakhmawati; Yunus
reen pellets (GPs), prepared at different compression pressures (cs = 6, 7.5 and 12 metric tonne) from mixtures containing self‐adhesive carbon grains (sacg) from the oil palm empty fruit bunch (EFB) and different percentages (pr = 0 to 90%) of a non self‐adhesive powder of petroleum green coke (ppgc), were carbonized (800° C) and activated with CO2 to produce carbon pellets (CPs). The measured electrical conductivity (σ) of the CP for all cs showed a curve having a minimum value at pr around 50%, indicating that the conducting phase displays a nonlinear σ‐ pr relationship. A significant increase in the σ due to CO2 activation was observed. For a sufficienctly high cs, an existence of a pr range in which the σ varies linearly with the density was also observed. These results provide some new information for modifying the electrical conductivity of carbon derived from the sacg from EFB or other types of biomass.
Impedance spectroscopic analysis of composite electrode from activated carbon/conductive materials/ruthenium oxide for supercapacitor applications
(2015-09-07) Taer, Erman; Deraman, Mohamad; Talib; Awitdrus; Farma, Rakhmawati; Ishak; Omar, Ramli; Dollah, Besek Nurdiana Mohd; Basri, Nur Hamizah; Othman; Kanwal
Activated carbon powders (ACP) were produced from the KOH treated pre-carbonized rubber wood sawdust. Different conductive materials (graphite, carbon black and carbon nanotubes (CNTs)) were added with a binder (polivinylidene fluoride (PVDF)) into ACP to improve the supercapacitive performance of the activated carbon (AC) electrodes. Symmetric supercapacitor cells, fabricated using these AC electrodes and 1 molar H2SO4 electrolyte, were analyzed using a standard electrochemical impedance spectroscopy technique. The addition of graphite, carbon black and CNTs was found effective in reducing the cell resistance from 165 to 68, 23 and 49 Ohm respectively, and increasing the specific capacitance of the AC electrodes from 3 to 7, 17, 32 F g-1 respectively. Since the addition of CNTs can produce the highest specific capacitance, CNTs were chosen as a conductive material to produce AC composite electrodes that were added with 2.5 %, 5 % and 10 % (by weight) electro-active material namely ruthenium oxide; PVDF binder and CNTs contents were kept at 5 % by weight in each AC composite produced. The highest specific capacitance of the cells obtained in this study was 86 F g-1, i.e. for the cell with the resistance of 15 Ohm and composite electrode consists of 5 % ruthenium oxide.
Influence of gamma irradiation exposure on the performance of supercapacitor electrodes made from oil palm empty fruit bunches
(2015-08-18) Nor, Najah Syahirah Mohd; Deraman, Mohamad; Omar, Ramli; Awitdrus; Farma, Rakhmawati; Basri, Nur Hamizah; Dolah, Besek Nurdiana Mohd; Mamat, Nurul Fatin; Yatim, Baharudin; Daud, Mohd Norizam Md
Carbon-monolith electrodes for supercapacitors were prepared from GMs (green monoliths) made from pre-carbonized fibers of oil palm EFB (empty fruit bunches) and GMs of pre-carbonized EFB fibers exposed to gamma radiation at 5 kGy, 15 kGy, and 20 kGy. GMs and irradiated GMs were carbonized and activated to prepare ACM (activated-carbon-monolith) electrodes. The gamma radiation affected the pore structure of the ACM electrodes and the electrochemical performance of the supercapacitors; irradiation doses of 0 kGy, 5 kGy, 15 kGy and 20 kGy produced specific capacitances of 121 F g 1, 196 F g 1, 11 F g 1, and 12 F g 1, respectively. The irradiation dose of 5 kGy appears to be optimum and produces a specific power and specific energy of 236 W kg 1 and 5.45 W h kg 1, respectively, representing 34% and 60% increases over ACM electrodes prepared from non-irradiated GMs.
A method to produce binderless supercapacitor electrode monoliths from biomass carbon and carbon nanotubes
(2015-08-18) Dolah; Deraman; Othman; Farma, Rakhmawati; Awitdrus
Binderless supercapacitor electrode monoliths (BSEM), prepared via the carbonization and activation of green monoliths from (a) self-adhesive carbon grains (SACG) from oil palm empty fruit bunch fibers, (b) SACG mixed with KOH, and (c) mixtures of SACG, KOH, and varying percentages of carbon nanotubes (CNTs), were characterized and evaluated in symmetrical supercapacitor cells. The porosity and the structural and microstructural characteristics of the electrodes are influenced by KOH and CNTs. The electrodes containing CNTs have a relatively lower specific capacitance but exhibit lower equivalent series resistance values and hence can sustain or improve the specific power of the cells, suggesting the need to optimize the quantity of CNTs used to sustain higher specific capacitance above 100 F/g. This innovative process uses inexpensive SACG with relatively small quantities of CNTs and KOH with no binder, and it directly combines both chemical (KOH) and physical (CO2) activation during the production of BSEM.
Microcrystallite Dimension and Total Active Surface Area of Carbon Electrode from Mixtures of Pre-Carbonized Oil Palm Empty Fruit Bunches and Green Petroleum Cokes
(2015-09-07) Awitdrus; Deraman, Mohamad; Talib; Omar, Ramli; Jumali, Mohd Hafizuddin; Taer, Erman; Saman, Mansor mohd
Carbon pellets (CP) were prepared from the green pellets (GP) containing mixtures of pre-carbonized oil palm empty fruit bunches (SACG) and Green Petroleum Cokes (GPC), with the weight percentages (x) of SACG in the samples at 10%, 30%, 50%, 70% and 90%. Carbonization process to produce the CP was conducted up to 900oC using a multi steps heating profile. The interlayer spacing (d200 and d100), stack height (Lc), stack width (La,) and effective dimension L of the turbostratic crystallites (microsrystallite) in the CPs were estimated from X-ray diffraction data; d200, d100, La, L increased and Lc decreased with increasing weight percentage of SACG. The total surface area of active material of the CP (Atot) with thickness, t, estimated from Lc was found to follow the equation, Atot = [4.8086 – 0.0083x]1010 t, indicating a significant influence of the SACG content in the mixture of the green body.
Nanoporous separators for supercapacitor using activated carbon monolith electrode from oil palm empty fruit bunches
(2015-09-06) Nor, Najah Syahirah Mohd; Deraman, Mohamad; Omar, Ramli; Taer, Erman; Awitdrus; Farma, Rakhmawati; Basri, Nur Hamizah
Activated porous carbon electrode prepared from fibres of oil palm empty fruit bunches was used for preparing the carbon based supercapacitor cells. The symmetrical supercapacitor cells were fabricated using carbon electrodes, stainless steel current collector, H2SO4 electrolyte, and three types of nanoporous separators. Cells A, B and C were fabricated using polypropylene, eggshell membrane, and filter paper, respectively. Electrochemical characterizations data from Electrochemical Impedance Spectroscopy, Cyclic Voltammetry, and Galvanic Charge Discharge techniques showed that specific capacitance, specific power and specific energy for cell A were 122 F g-1, 177 W kg-1, 3.42 Wh kg-1, cell B; 125 F g- 1, 179 W kg-1, and 3.64 Wh kg-1, and cell C; 180 F g-1, 178 W kg-1, 4.27 Wh kg-1. All the micrographs from Field Emission Scanning Electron Microscope showed that the different in nanoporous structure of the separators lead to a significant different in influencing the values of specific capacitance, power and energy of supercapacitors, which is associated with the mobility of ion into the pore network. These results indicated that the filter paper was superior than the eggshell membrane and polypropylene nanoporous separators. However, we found that in terms of acidic resistance, polypropylene was the best nanoporous separator for acidic medium.
A New Empirical Equation for Estimating Specific Surface Area of Supercapacitor Carbon Electrode from X-ray Diffraction
(2015-08-18) Deraman, Mohamad; Daik, Rusli; Soltaninejad, Sepideh; Nor, Najah Syahirah Mohd; Awitdrus; Farma, Rakhmawati; Mamat, Nurul Fatin; Basri, Nur Hamizah; Othman, Mohd Amir Radhi
The current trend of increasing research interest in supercapacitor is due to high demands for an energy storage device that can work in systems that require either low or high power-energy usage. In a supercapacitor using porous carbon electrodes, the energy storage mechanism involves the electrolyte ions in electrode pores and electronic charges in electrodes to form electric double layers at the electrode-electrolyte interface without undergoes any chemical reaction. The specific surface area of porous electrodes, which affect the performance of supercapacitor, have been widely investigated by many researchers using the nitrogen adsorption-desorption measurement. However, despite its simplicity, the X-ray diffraction method is rarely found being used to determine the specific surface area of porous electrodes. Therefore, in the present paper, we propose a new equation which expressed the specific surface area of electrodes as a function the electrode structural parameters obtained from the X-ray diffraction data, and duration of activation time employed during the electrode preparation. This equation is found to produce a satisfactory result and is expected to be beneficial for studying supercapacitor electrode materials
Physical and electrochemical properties of supercapacitor composite electrodes prepared from biomass carbon and carbon from green petroleum coke
(2015-09-09) Awitdrus; Deraman, Mohamad; Talib; Farma, Rakhmawati; Omar, Ramli; Ishak; Taer, Erman; Dollah, Besek Nurdiana Mohd; Basri, Nur Hamizah; Nor, Najah Syahirah Mohd
The green monoliths (GMs) were prepared from the mixtures of pre-carbonized fibers of oil palm empty fruit bunches (or self-adhesive carbon grains (SACG)) and green petroleum coke (GPC) with the mixing ratio of 0, 10, 30, 50 and 70 % GPC, respectively. The GMs were carbonized in N2 environment at 800oC to produce carbon monoliths (CM00, CM10, CM30, CM50 and CM70). The CMs were CO2 activated at 800oC for 1 hour to produced activated carbon monolith electrodes (ACM00, ACM10, ACM30, ACM50 and ACM70). For each percentage of GPC, three duplicate symmetrical supercapacitor cells were fabricated using these activated carbon monolith electrodes respectively, and the capacitive performance amongst the cells was compared and analyzed in order to observe the relationship between the capacitive performance and the physical properties (microstructure and porosity) of the ACMs electrodes containing varying percentage of GPC.
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.
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
Self-Adhesive Carbon Grains Derived From Fibers Of Oil Palm Empty Fruit Bunches For Binderless Carbon/Carbon Nanotubes Composite Electrodes For Supercapacitor Application
(2015-09-09) Ishak; Deraman, Mohamad; Farma, Rakhmawati; Awitdrus; Taer, Erman; Talib
Amongst the current trend in the study of carbon composite electrodes is the addition of carbon nano particles, without binding materials, into conventional carbon to produce electrode in order to benefit from both the unique property of the nano particles and the absent of the binder which can improve the specific capacitance of the electrodes. In our study, we produce the binderless carbon/carbon nanotubes composite electrodes for supercapacitor application from the green pellets consist of self-adhesive carbon grain from fibers of oil palm empty fruit bunch and 0, 6 and 8% carbon nanotubes (CNTs), respectively. This paper reports the electrodes properties, i.e., microstructure, electrical conductivity, porosity and electrochemical, based on the characterization using Field Emission Scanning Electron Microscope, four-point-probe, nitrogen adsorptiondesorption isotherm, electrochemical impedance spectroscopy and cyclic voltammetry techniques. The results show that supercapacitor cell using the electrodes with 6% CNTs has a better supercapacitive behavior.

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