• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.7
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• pp.16-22
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• 2012

With the increase of consumption of new renewable energy, the use of Electric Double Layer Capacitor(EDLC) is being gradually widened as the next generation energy storage device. In order to expand the market of EDLC which is recently receiving a lot of attraction as a new promising area, development of a charge/discharge cycle tester to measure and test performance, is essential. Therefore, this research designed a circuit to measure capacity and internal resistance and a circuit to measure voltage maintenance properties, based on EDLC's basic charging/discharging properties so it is able to measure the state of charge and discharge at high speed. When evaluating performance characteristics, the 5[V]/100[A] prototype-EDLC charge/discharge testing system developed for this research showed ${\pm}0.1$[%] of accuracy of voltage and current measurement. It was also proved that the developed charge/discharge testing system for EDLC can be applied to the actual industry, when testing the entire system using a program produced for data monitoring and acquisition.

• Proceedings of the Korean Fiber Society Conference
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• 2003.04a
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• pp.91-94
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• 2003

탄소재료는 높은 전기전도도 및 기계적 강도, 화학적 안정성, 큰 비표면적(1000~3000 $m^2$/g) 등의 특성 때문에 연료전지, 리튬이온 이차전지, 전기이중층 캐패시터(electric double layer capacitor, EDLC)의 전극활물질로 주목받고 있다[1]. 일반적으로 활성탄소섬유는 1000~3000 $m^2$/g의 비표면적을 갖기 때문에 종래의 필름 콘덴서와 세라믹 콘덴서에 비해 비약적인 고용량(체적당 수천 배, Farad급)을 얻을 수 있다. 전기이중층 캐패시터는 수명이 반영구적이며 사용온도의 범위가 넓고 안전하다는 장점을 지니고 있으며 이러한 캐패시터의 성능은 전극으로 사용되는 활성탄소 섬유의 비표면적, 세공의 크기, 구조 및 형태, 표면의 관능기 및 전기 전도도 등의 특성에 크게 좌우된다[1-3]. (중략)

• Journal of the Korean Electrochemical Society
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• v.20 no.2
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• pp.34-40
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• 2017

Electric double layer capacitors (EDLC: electric double layer capacitors) have drew attention as an energy storage device for the next generation because of their outstanding power capability and durability. But their usage is somewhat limited due to low energy density over secondary batteries. One of methods to improve the energy of EDLC is expanding the voltage window of cell operation by increasing the charge cut-off voltage. In this study, $SBP-BF_4$ (spirobipyrrolidinium tetrafluoroborate), $TEA-BF_4$ (tetraethylammonium tetraflouroborate) and $EMI-BF_4$ (1-ethyl-3-methylimidazolium tetrafluoroborate) in AN (acetonitrile) were selected to evaluate the possibility of application at high voltage environment. The LSV (linear sweep voltammetry) measurements showed that the 1.5M SBP-BF4/AN electrolyte was stable over a wide potential window and showed the best electrochemical performance compared to other combinations of electrolytes at high voltage environments (over 3.0 V). Furthermore, TMSP (tris(trimethylsilyl) phosphite) was applied to 1.5M SBP-BF4/AN in order to maintain stable performance at high voltage for the long period of time. The electrolyte with TMSP additive showed the capacity retention of 93% after 10,000 cycles at 3.3 V.

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.638-644
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• 2017

Pitch based activated carbon fibers for electric double layer capacitor (EDLC) electrodes were treated by oxyfluorination via varying the ratio of fluorine and oxygen gases to improve high power property. As the partial pressure of fluorine increased, the oxyfluorinated activated carbon fibers showed an increase of linear fluorine functional groups. While the oxygen functional groups increased, no changes was observed with respect to the partial gas pressure. The specific surface area and pore volume decreased due to the etching reaction on the activated carbon fiber surface through oxyfluorination, but the mesopore volume increased about 4.5 times. In the case of activated carbon fibers treated with 50% of the fluorine gas partial pressure, the specific capacitance increased to about 29% and 61% at scan rates of 5 and 50 mV/s, respectively. The improvement of the specific capacitance was believed to be due to the introduction of oxygen and fluorine functional groups on the activated carbon fiber surface and the increase of mesopores through oxyfluorination.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1099-1101
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• 2007

In this paper, a study has been performed for development of dynamic voltage restorer(DVR) system using EDLC (Electric Double Layer Capacitor) to solve voltage sags which are considered the dominant disturbances affecting power quality. With the prolific use of semiconductor devices in electrical equipment, modern-day loads are becoming increasingly sensitive to the sags and the disturbances prove to be costly to industries. As a technology-driven custom power installation, the Dynamic Voltage Restorer (DVR) is recognized to be most effective equipment that can be used to counter the voltage sag problem. Hence, this paper proposes the high-performance optimal design of On-Line type DVR system which can efficiently compensate the instantaneous voltage sag and instantaneous interruption of the utility voltage source.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2190-2195
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• 2011

Due to enhanced demands on quality, security and reliability of the electric power energy system, a microgrid has become a subject of special interest. In this paper, output characteristics of energy storage system (ESS) with an electric double layer capacitor (EDLC) and battery energy storage system (BESS) of a renewable energy based microgrid were analyzed under grid-connected and islanded operation modes. The microgrid which consists of photovoltaic and wind power turbine generators, diesel generator, ESS with an EDLC, BESS and loads was modeled using real time digital simulator. The results present the effective control patterns of the microgrid system.

• Korean Journal of Materials Research
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• v.26 no.9
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• pp.460-467
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• 2016

Activated carbons (ACs) have been used as EDLC (electric double-layer capacitor) electrode materials due to their high specific area, stability, and ecological advantages. In order to prepare ACs with high density and crystallinity, coal tar pitch (CTP) was activated by $K_2CO_3$ and the textural and electrochemical properties of the obtained ACs were investigated. Although the CTP ACs formed by $K_2CO_3$ activation had much smaller specific surface area and pore volume than did the CTP ACs formed by KOH activation, their volumetric specific capacitance (F/cc) levels as electrode materials for EDLC were comparable due to their higher density and micro-crystallinity. Structural characterization and EDLC-electrode performance were studied with different activation conditions of $CTP/K_2CO_3$ ratio, activation temperature, and activation period.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.4
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• pp.335-339
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• 2016

Output power in photovoltaic systems changes steeply with the change of the sun intensity. The change of output power has influence on the electric power quality of the system. This paper proposes a residential distributed generation system using photovoltaic power generation and polymer electrolyte fuel cells(hybrid systems). In order to level the output power which changes steeply the polymer electrolyte fuel cells are connected to the photovoltaic power generation system in parallel. Thus the generated power of all the system can be leveled. However, the steep generated power in the photovoltaic power generation system can not be leveled. Therefore, the electric double layer capacitor(EDLC) is connected in parallel with the hybrid systems. It is confirmed by the simulation that the proposed distributed generation system is available for a residential supply.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.814-821
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• 1999

The specific capacitance characteristics of the electric double layer capacitors(ELDC) which were made of phenol based activated carbon fiber(ACF) electrodes. Also the effect of aqueous electrolytes on the cell performance has been investigated with respect to different specific surface areas of electrodes and different kinds of aqueous electrolytes. It has been shown that larger surface area and pore size, higher conductivity of electrodes, and higher ion mobility of electrolytes have better specific capacitances. It has been found that heat treatment at $1200^{\circ}C$ and $CO_2$ post-activation at $900^{\circ}C$ of the electrode are effective to improve the specific capacitance over 145F/g and 165F/g, respectively. The EDLC showed high efficiency and long cycle life over 30000 cycles.

• Journal of the Korean Electrochemical Society
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• v.14 no.1
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• pp.38-43
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• 2011

Because the ionic liquid added with Propylene carbonate(PC) at room temperature has lower viscosity than original, we considered electrochemical behavior of it in EDLC. The ionic liquid without PC which does not have ions has no problem in capacity since it has enough ions. The electrolyte resistance was decreased with decreasing viscosity. As a result of identifying high current discharge capacity, we observed that the ionic liquid had capacity of 73.12% at current density of $80\;mA/cm^{-2}$, but it increased to 81.94% at PC content of 40 vol%.