• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1609-1611
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• 1997

We fabricated five type of electric double layer capacitor(EDLC) with extremely stable activated carbon as a positive and negative electrodes. The electrodes consisted of activated carbon and several different conductor layers on aluminium foil. Cyclic voltammogram of activated carbon electrodes at scan rate 5mV/sec was reversable redox reaction. The discharge capacity of activated carbon-KS 6 composite electrode was higher than that of activated carbon electrode without KS 6.

• Carbon letters
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• v.24
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• pp.73-81
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• 2017

Interconnected meso/microporous activated carbons were prepared from pumpkin seeds using a simple chemical activation method. The porous carbon materials were prepared at different temperatures (PS-600, PS-700, PS-800, and PS-900) and demonstrated huge surface areas ($645-2029m^2g^{-1}$) with excellent pore volumes ($0.27-1.30cm^3g^{-1}$). The well-condensed graphitic structure of the prepared activated carbon materials was confirmed by Raman and X-ray diffraction analyses. The presence of heteroatoms (O and N) in the carbon materials was confirmed by X-ray photoemission spectroscopy. High resolution transmission electron microscopic images and selected area diffraction patters further revealed the porous structure and amorphous nature of the prepared electrode materials. The resultant porous carbons (PS-600, PS-700, PS-800, and PS-900) were utilized as electrode material for supercapacitors. To our delight, the PS-900 demonstrated a maximum specific capacitance (Cs) of $303F\;g^{-1}$ in 1.0 M $H_2SO_4 $ at a scan rate of 5 mV. The electrochemical impedance spectra confirmed the poor electrical resistance of the electrode materials. Moreover, the stability of the PS-900 was found to be excellent (no significant change in the Cs even after 6000 cycles).

• Carbon letters
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• v.18
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• pp.76-79
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• 2016

• Carbon letters
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• v.14 no.2
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• pp.126-130
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• 2013

In this study, we present a more electrochemically enhanced electrode using activated carbon (AC)-sulfur (S) composite materials, which have high current density. The morphological and micro-structure properties were investigated by transmission electron microscopy. Quantity of sulfur was measured by thermogravimetric analysis analysis. The electrochemical behaviors were investigated by cyclic voltammetry. As a trapping carbon structure, AC could provide a porous structure for containing sulfur. We were able to confirm that the AC-S composite electrode had superior electrochemical activity.

• Journal of Electrochemical Science and Technology
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• v.14 no.2
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• pp.184-193
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• 2023

This study investigates the effects of a carbon fiber layer formed on the surface of an etched aluminum current collector on the electrochemical properties of the activated carbon electrodes for an electric double layer capacitor. A particle size analyzer, field-emission SEM, and nitrogen adsorption/desorption isotherm analyzer are employed to analyze the structure of the carbon fiber layer. The electric and electrochemical properties of the activated carbon electrodes using a carbon fiber layer are evaluated using an electrode resistance meter and a charge-discharge tester, respectively. To uniformly coat the surface with carbon fiber, we applied a planetary mill process, adjusted the particle size, and prepared the carbon paste by dispersing in a binder. Subsequently, the carbon paste was coated on the surface of the etched aluminum current collector to form the carbon under layer, after which an activated carbon slurry was coated to form the electrodes. Based on the results, the interface resistance of the EDLC cell made of the current collector with the carbon fiber layer was reduced compared to the cell using the pristine current collector. The interfacial resistance decreased from 0.0143 Ω·cm² to a maximum of 0.0077 Ω·cm². And degradation reactions of the activated carbon electrodes are suppressed in the 3.3 V floating test. We infer that it is because the improved electric network of the carbon fiber layer coated on the current collector surface enhanced the electron collection and interfacial diffusion while protecting the surface of the cathode etched aluminum; thereby suppressing the formation of Al-F compounds.

• Carbon letters
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• v.22
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• pp.70-80
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• 2017

Activated carbons (ACs) have been used as electrode materials of electric double-layer capacitors (EDLC) due to their high specific surface areas (SSA), stability, and ecological advantages. In order to make high-energy-density ACs for EDLC, petroleum pitch (PP) pre-carbonized at $500-1000^{\circ}C$ in $N_2$ gas for 1 h was used as the electrode material of the EDLC after KOH activation. As the pre-carbonization temperature increased, the SSA, pore volume and gravimetric capacitance tended to decrease, but the crystallinity and electrode density tended to increase, showing a maximum volumetric capacitance at a medium carbonization temperature. Therefore, it was possible to control the crystalline structure, SSA, and pore structure of AC by changing the pre-carbonization temperature. Because the electrode density increased with increasing of the pre-carbonization temperature, the highest volumetric capacitance of 28.4 F/cc was obtained from the PP pre-carbonized at $700^{\circ}C$, exhibiting a value over 150% of that of a commercial AC (MSP-20) for EDLC. Electrochemical activation was observed from the electrodes of PP as they were pre-carbonized at high temperatures above $700^{\circ}C$ and then activated by KOH. This process was found to have a significant effect on the specific capacitance and it was demonstrated that the higher charging voltage of EDLC was, the greater the electrochemical activation effect was.

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.552-559
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• 2020

Activated carbon-nickel (II) oxide (AC-NiO) electrodes were studied as materials for the capacitive deionization (CDI) of aqueous sodium chloride solution. AC-NiO electrodes were fabricated through physical mixing and low-temperature heating of precursor materials. The amount of NiO in the electrodes was varied and its effect on the deionization performance was investigated using a single-pass mode CDI setup. The pure activated carbon electrode showed the highest specific surface area among the electrodes. However, the AC-NiO electrode with approximately 10 and 20% of NiO displayed better deionization performance. The addition of a dielectric material like NiO to the carbon material resulted in the enhancement of the electric field, which eventually led to an improved deionization performance. Among all as-prepared electrodes, the AC-NiO electrode with approximately 10% of NiO gave the highest salt adsorption capacity and charge efficiency, which are equal to 7.46 mg/g and 90.1%, respectively. This finding can be attributed to the optimum enhancement of the physical and chemical characteristics of the electrode brought by the addition of the appropriate amount of NiO.

• Carbon letters
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• v.6 no.1
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• pp.25-30
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• 2005

The electrosorption of U(VI) from waste water was carried out by using an activated carbon fiber (ACF) felt electrode in a continuous electrosorption cell. In order to enhance the electrosorption capacity at a lower potential, the ACF was electrochemically modified in an acidic and a basic solution. Pore structure and functional groups of the electrochemically modified ACF were examined, and the effects of the modification conditions were studied for the adsorption of U(VI). Specific surface area of all the ACFs was decreased by this modification. The amount of the acidic functional groups decreased with a basic modification, while the amount increased a lot with an acidic modification. The electrosorption capacity of U(VI) decreased on the acid modified electrode due to the shielding effect of the acidic functional groups. The base modified electrode enhanced the capacity due to a reduction of the acidic functional groups. The electrosorption amount of U(VI) on the base modified electrode at .0.3 V corresponds to that of the as-received ACF electrode at .0.9 V. Such a good adsorption capacity was due to a reduction of the shielding effect and an increase of the hydroxyl ions in the electric double layer on the ACF surface by the application of negative potential.

• Nuclear Engineering and Technology
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• v.47 no.5
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• pp.579-587
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• 2015

To support the use of nuclear power as a sustainable electric energy generating technology, long-term supply of uranium is very important. The objective of this research is to investigate the use of new adsorbent material for cost effective uranium extraction from seawater. An activated carbon-based adsorbent material is developed and tested through an electrosorption technique in this research. Adsorption of uranium from seawater by activated carbon electrodes was investigated through electrosorption experiments up to 300 minutes by changing positive potentials from +0.2V to +0.8V (vs. Ag/AgCl). Uranium adsorption by the activated carbon electrode developed in this research reached up to 3.4 g-U/kg-adsorbent material, which is comparable with the performance of amidoxime-based adsorbent materials. Electrosorption of uranium ions from seawater was found to be most favorable at +0.4V (vs. Ag/AgCl). The cost of chemicals and materials in the present research was compared with that of the amidoxime-based approach as part of the engineering feasibility examination.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.595-596
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• 2005

This research which it sees adds $LiMn_2O_4$ in the activated carbon electrode the test against the effect which it follows is. Test cells, which were $LiMn_2O_4$fabricated with active mass composite consisted of (100-X)% of MSP-20 and (X)% of $LiMn_2O_4$ (X=20,40,60,80,100), exhibits the better specific capacitance than those of the cells fabricated with single active mass that is MSP-20. The enhanced properties of composite active mass could be caused by capability of $LiMn_2O_4$ powders. But the resistance was increase by proportionate in $LiMn_2O_4$ addition and when mixture ratio of the activated carbon and the $LiMn_2O_4$ being similar, to be low rather to the after where had become the maximum it came.