• 공업화학
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• 제10권6호
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• pp.814-821
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• 1999

고비표면적의 활성탄소섬유(ACF: activated carbon fiber)를 분극성 전극으로 이용한 전기이중층 캐패시터(electric double layer capacitor)의 단위 cell test를 통하여, ACF의 비표면적, 세공의 크기 및 전기전도도가 캐패시터의 비축전용량에 커다란 영향을 미치고 있음을 확인할 수 있었고, 전해질은 $H^+$ 이온을 함유한 $H_2SO_4$이 가장 좋은 축전용량을 나타내었으나, 집전체 부식 등의 문제로 인하여, 실용화에 있어서는 우수한 충방전 거동을 나타낸 KOH계 전해질이 적당한 것으로 확인되었다. 분극성 전극으로 사용되는 ACF를 탄화 또는 후활성화 등이 후처리를 통하여 비축전용량을 급격히 증가시킬수 있었고, 3만회까지의 연속 충방전 실험에서 전기이중층 캐패시터는 2차전지에서는 찾아 볼 수 없는 매우 높은 충방전 효율과 긴 사용수명을 가지는 것을 확인할 수 있었다.

• 한국세라믹학회지
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• 제45권8호
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• pp.482-485
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• 2008

Composite electrode consisting of carbon nanofiber (CNF) and cobalt oxide was prepared for supercapacitor electrode, and its electrochemical property was investigated by means of cyclic voltammetry. Cyclic voltammetric results for the composite electrode showed it had specific capacitance value of 420 F/g at 5 mV/s, which was higher than capacitance value of 180 F/g for the bare CNF. It is concluded that the capacitive property of CNF can be improved by coating cobalt oxide on it to increase the surface area of cobalt oxide.

• Carbon letters
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• 제1권3_4호
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• pp.133-137
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• 2001

Mesoporous activated carbon fiber (ACF) was prepared from phenolic resin containing a small amount (0.1 wt %) of organic nickel complex through carbonization and steam activation. Microporous ACF as reference sample was also prepared from phenolic resin without agent. In both cases of the mesoporous ACFs and the microporous ACFs, the electric double layer capacitance of the nonaqueous electrolyte (0.5 M $TEABF_4$/PC or 1.0 M $LiClO_4$/PC) was not proportional to the BET specific surface area. This is owing to the low permeability of nonaqueous electrolyte or the low mobility of ion in narrow micropores. However, the mesoporous ACF showed higher double layer capacitance than the microporous (normal) ACF. This result suggests that the presence of many mesopores promotes the formation of effective double layer or the transfer of ion in the micropore.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1972-1978
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• 2012

The polymer of (2,2-dimethyl-1,3-propanediaminebis(salicylideneaminato))-nickel(II), Ni(saldMp), was deposited on multi-walled carbon nanotubes (MWCNTs) substrate by the route of potential linear sweep. The nano structures of poly[Ni(saldMp)] have been obtained by adjusting the monomer concentration of 0.1, 0.2, 0.5, 1.0 and 1.5 mmol $L^{-1}$. The poly[Ni(saldMp)] prepared in acetonitrile solution with monomer concentration of 1.0 mmol $L^{-1}$ shows the fastest growth rate. The effects of potential window on charge-discharge efficiency and electrodeposition scan number on capacitance performance were discussed. Poly[Ni(saldMp)] prepared with less electrodeposition scans exhibits higher capacitance, but this goes against the improvement of the whole electrode capacitance. Sample with 8 deposition scans is the best compromise with the geometric specific capacitance 3.53 times as high as that of pure MWCNTs, and 1.24 times for the gravimetric specific capacitance under the test potential window 0.0-1.0 V.

• 전기화학회지
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• 제16권2호
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• pp.65-69
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• 2013

전기이중층 커패시터용 활성탄의 정전 용량 향상을 위해 우레아를 이용해 활성탄 표면에 펩티드 결합을 유도하였다. 우레아 도입에 따른 활성탄은 소성과정을 거쳐 안정화되었으며, 전기화학적 특성을 순환전류 전압법을 이용하여 정전 용량을 관찰하고, 임피던스를 통해 저항 변화를 관찰하였으며, 충방전 평가를 통해 싸이클 성능을 관찰하였다. 결과적으로 질소성 작용기의 도입으로 정전 용량은 기존 탄소재에 비해 약 22.9%의 향상을 이루었으며, 저항 감소 및 우수한 싸이클 성능을 나타냄을 확인하였다.

• Advances in Energy Research
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• 제8권1호
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• pp.41-57
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• 2022

Electrochemical double-layer capacitors (EDLCs) based on solid polymer electrolytes (SPEs) have gained an immense recognition in the present world due to their unique properties. This study is about preparing and characterizing EDLCs using a natural rubber (NR) based SPE with natural graphite (NG) electrodes. NR electrolyte was consisted with 49% methyl grafted natural rubber (MG49) and zinc trifluoromethanesulfonate ((Zn(CF₃SO₃)₂-ZnTF). It was characterized using electrochemical impedance spectroscopy (EIS) test, dc polarization test and linear sweep voltammetry (LSV) test. NG electrodes were made using a slurry of NG and acetone. EIS test, cyclic voltammetry (CV) test and galvanostatic charge discharge (GCD) test have been done to characterize the EDLC. Optimized electrolyte composition with NR: 0.6 ZnTF (weight basis) exhibited a conductivity of 0.6 x 10^-4 Scm^-1 at room temperature. Conductivity was predominantly due to ions. The electrochemical stability window was found to be from 0.25 V to 2.500 V. Electrolyte was sandwiched between two identical NG electrodes to fabricate an EDLC. Single electrode specific capacitance was about 2.26 Fg^-1 whereas the single electrode discharge capacitance was about 1.17 Fg^-1. The EDLC with this novel NR-ZnTF based SPE evidences its suitability to be used for different applications with further improvement.

• Journal of Electrochemical Science and Technology
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• 제10권4호
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• pp.387-393
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• 2019

Activated carbons (ACs) are considered important electrode materials for supercapacitors because their large specific surface areas lead to high charging capacities. In the conventional synthesis of ACs, a substantial amount of carbon is lost during carbonization of a precursor. The development of a method to synthesize ACs in high yield would lower their manufacturing cost. Here, we demonstrate the synthesis of high-specific-surface-area NaOH-AC from carbon prepared via a hydrothermal carbonization (HTC) route, with a higher yield than that achieved through conventional pyrolysis carbonization. The amorphous carbon was derived from HTC of sugar and subsequently activated at 800℃ with various NaOH etchant/C ratios under a N₂ atmosphere. The AC prepared at 4:1 NaOH/C exhibited the highest surface area (as high as 2,918 ㎡ g^-1) and the highest specific capacitance (157 F g^-1 in 1 M aqueous Na₂SO₄ electrolyte solution) among the NaOH-AC samples prepared in this work. On the basis of their high specific capacitance, the NaOH-ACs prepared from HTC sugar are suitable for use as electrode materials for supercapacitors.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.214.1-214.1
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• 2011

In this work, the electrochemical properties of the surface treated multi-walled carbon nanotubes (MWNTs) are investigated for supercapacitors. Nitrogen- and oxygen functional groups containing MWNTs are prepared by nitrogen precursors and acidic treatment, respectively. The surface properties of the MWNTs are confirmed by X-ray photoelectron spectroscopy (XPS) and Zeta-potential measurements. The electrochemical properties of the MWNTs are investigated by cyclic voltammetry, impedance spectra, and charge-discharge cycling performance in 1 M $H_2SO_4$ at room temperature. As a result, these functionalized MWNTs lead to an increase in the specific capacitance as compared with the pristine MWNTs. It proposes that the pyridinic and pyridinic-N-oxides nitrogen species influence on the specific capacitance due to their positive charges, and thus an improved electron transfer at high current loads, since they are the most important functional groups affecting capacitive behaviors.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.1140-1143
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• 2002

This work describes the effect of conducting composite on the characteristics of electric double layer capacitor. The cell, which was fabricated with conducting composite consisted of 50 wt.% of SPB and 50 wt.% of VGCF, exhibits the higher specific capacitance, the lower resistance and the better rate capability than those of the cells fabricated with each single electronic conductor. These enhanced properties could be related with the dense structure of electrode.

• Carbon letters
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• 제12권4호
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• pp.252-255
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• 2011

Carbon-based electric double-layer capacitors are being evaluated as potential energy-storage devices in an expanding number of applications. In this study, samples of carbon black (CB) treated at different temperatures ranging from $650^{\circ}C$ to $1100^{\circ}C$ were used as electrodes to improve the efficiency of a capacitor. The surface properties of the heat-treated CB samples were characterized by X-ray photoelectron spectroscopy and X-ray diffraction. The effect of the heat-treatment temperature on the electrochemical behaviors was investigated by cyclic voltammetry and in galvanostatic charge-discharge experiments. The experimental results showed that the crystallinity of the CBs increased as the heat-treatment temperature increased. In addition, the specific capacitance of the CBs was found to increase with the increase in the heat-treatment temperature. The maximum specific capacitance was 165 $F{\cdot}g-1$ for the CB sample treated at $1000^{\circ}C$.