• Journal of the Korean Electrochemical Society
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• v.6 no.3
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• pp.174-177
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• 2003

Electric double-layer capacitors based on charge storage at the interface between a high surface area activated carbon electrode and an electrolyte solution are characterized by their long cycle-life and high power density in comparison with batteries. However, energy density of electric double-layer capacitors obtained at present is about 6 Wh/kg at a power density of 500W/kg which is smaller as compared with that of batteries and limits the wide spread use of the capacitors. Therefore, a new capacitor that shows larger energy density than that of electric double-layer capacitors is proposed. The new capacitor is the hybrid capacitor consisting of activated carbon cathode, carbonaceous anode and an organic electrolyte. Maximum voltage applicable to the cell is over 4.2V that is larger than that of the electric double-layer capacitor. As a result, discharged energy density on the basis of stacked volume of electrode, current collector and separator is more than 18Wh/l at a power density of 500W/l.

• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.108-111
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• 2007

A novel voltage sag compensator with hi-directional DC/DC converter of Electric double layer capacitor is proposed. Recently, the double-layer capacitor which is drawn attention as a new energy storage element has a lot of advantage such as no maintenance, long lifetime and quick charge/discharge characteristics with large current. This DC/DC converter is used to control the charging current to the double-layer capacitor and also used to keep the DC link voltage constant for discharge of the double-layer capacitor. Therefore, the proposed DC/DC converter has the high-efficiency controller, dynamic compensator of voltage sag is driven by this converter. Finally, experimental results show the validity of the control scheme and the ability of the dynamic voltage compensator.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.6
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• pp.627-634
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• 2018

Gallium-based liquid metal, e.g., eutectic gallium-indium (EGaIn), is highly attractive as an electrode material for flexible and stretchable devices. On the liquid metal, oxide layer is spontaneously formed, which has a wide band-gap, and therefore is electrically insulating. In this paper, we fabricate a capacitor based on eutectic gallium-indium (EGaIn) liquid metal and investigate its cyclic voltammetry (CV) behavior. The EGaIn capacitor is composed of two EGaIn electrodes and electrolyte. CV curves reveal that the EGaIn capacitor shows the behavior of electric double-layer capacitors (EDLC), where the oxide layers on the EGaIn electrodes serves as the dielectric layer of EDLC. The oxide thicker than the spontaneously-formed native oxide decreases the capacitance of the EGaIn capacitor, due to increased voltage loss across the oxide layer. The EGaIn capacitor without oxide layer exhibits unstable CV curves during the repeated cycles, where self-repair characteristic of the oxide was observed. Finally, the electrolyte concentration is optimized by comparing the CV curves at various electrolyte concentrations.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.171-178
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• 2013

This paper discusses to conduct experimental verification of two types of micro electric vehicles (EV) in order to realize improvement in electric mileage and shorten a charging time of the battery. First, electric double layer capacitor (EDLC) systems to use as a secondary battery are proposed. The internal resistance of EDLC is small compared with a rechargeable battery, and it is suitable for momentary charge-discharge of EV. Next, control circuits of the capacitors to increase the regenerative electric power are utilized. Then, a novel method to charge a main battery of the EV is introduced. Finally, experimental results demonstrate the validity of the proposed method.

• Korean Journal of Materials Research
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• v.32 no.7
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• pp.313-319
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• 2022

Double-layer capacitors (DLCs) are developed with high surface electrodes to achieve a high capacitance value. In the present work, the initial bulk concentration of 1 mol/m³ and 3 mol /m³ are selected to show the consequential effects on the performance of a double-layer capacitor. A 1D model of COMSOL Multiphysics has been developed to analyze the electric field and potential in cell voltage, the electric displacement field and polarization induced by the field, and energy density in a double-layer structure. The electrostatics and the electric circuit modes in COMSOL are used to simulate the electrochemical processes in the double-layer structure. The analytical analysis of a double-layer capacitor with different initial bulk concentrations is investigated by using Poisson-Nernst-Plank equations. From the simulation results, the differential capacitance changes as a function of compact layer thickness and initial bulk concentration. The energy density varies with the differential capacitance and voltage window. The values of energy density are dominated by the interaction of ions in the solution and electrode surface.

• 한국전기화학회:학술대회논문집
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• 2003.11a
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• pp.195-206
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• 2003

• Journal of Electrical Engineering and Technology
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• v.8 no.2
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• pp.238-243
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• 2013

In this paper, a novel approach for optimized installation and operations of battery energy storage system (BESS) and electric double layer capacitor (EDLC) modules for the renewable energy based intermittent generation is presented for them to be connected with an electric power grid. In order to make use of not merely the high energy density of battery but also the high power density of EDLC modules, it is very useful to devise the hybrid system which combines BESS and EDLC modules. The proposed method adopts the linear programming to calculate the optimized capacity as well as the quadratic programming to transmit the optimal operational signals to BESS and EDLC modules. The efficiency of this methodology will be demonstrated in the experimental study with the real data of wind speed in Texas.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.1
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• pp.107-111
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• 2004

This work describes the effect of composite conductor on the characteristics of electric double layer capacitor. Test cell, which was fabricated with conducting composite consisted of 80％ of SPB and 20％ of VGCF, exhibits the better tate capability and the lower resistance than those of the cells fabricated with single electronic conductor. These enhanced properties could be related with the decrease of contact resistance between the activated carbon powders.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.211-214
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• 1998

The composite of polyvinylalcohol(PVA) and lithium salts(LiBF$_4$) is prepared for a solid-state electrolyte of electric double layer capacitor. The composite shows a good ionic conductivity. The solid-state electric double layer capacitor is made of PVA-LiBF$_4$ composite, activated carbon and etc.. As evaluation of characteristics of capacitor, capacitance change which measured by charge-discharge test with 2.2V~0V at 8$0^{\circ}C$ for 800 hours, was about 10%. The gravimetric and volumetric capacitance were 10.0 F/g~30.0 F/g and 16.0F/㎤~F/㎤, respectively.

• Applied Chemistry for Engineering
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• v.20 no.4
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• pp.396-401
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• 2009

A micro-spherical activated carbon with meso-pore structure of 52~64% and particle diameter of $2{\sim}10{\mu}m$ was prepared for the improvement electrochemical performance of activated carbon as electrode material for electric double layer capacitor. Resorcinol-formaldehyde resin was used as a carbon source in this preparation. According to electrochemical analysis of EDLC using this activated a carbon with showing effects to reduce charge transfer resistance and to increase rate capability, it was found out that micro-spherical activated carbon could be a good method as well as a material for enhancing the performance of electric double layer capacitor.