• 한국환경과학회지
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• 제29권4호
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• pp.383-393
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• 2020

To increase electrolysis performance, the applicability of seawater to the iron-fed electro-Fenton process was considered. Three kinds of graphite electrodes (activated carbon fiber-ACF, carbon felt, graphite) and dimensionally stable anode (DSA) electrode were used to select a cathode having excellent hydrogen peroxide generation and organic decomposition ability. The concentration of hydrogen peroxide produced by ACF was 11.2 mg/L and those of DSA, graphite, and carbon felt cathodes were 12.9 ~ 13.9 mg/L. In consideration of durability, the DSA electrode was selected as the cathode. The optimum current density was found to be 0.11 A/㎠, the optimal Fe²⁺ dose was 10 mg/L, and the optimal ratio of Fe²⁺ dose and hydrogen peroxide was determined to be 1:1. The optimum air supply for hydrogen peroxide production and Rhodamine B (RhB) degradation was determined to be 1 L/min. The electro-Fenton process of adding iron salt to the electrolysis reaction may be shown to be more advantageous for RhB degradation than when using iron electrode to produce hydrogen peroxide and iron ion, or electro-Fenton reaction with DSA electrode after generating iron ions using an iron electrode.

• 한국응용과학기술학회지
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• 제32권3호
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• pp.480-487
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• 2015

In this study, several kinds of active carbons with high specific surface area and micro pore structure were prepared from the coconut shell charcoal using chemical activation method. The physical property of prepared active carbon was investigated by experimental variables such as activating chemical agents to char coal ratio, flow rate of inert gas and temperature. It was shown that chemical activation with KOH and NaOH was successfully able to make active carbons with high surface area of $1900{\sim}2500m^2/g$ and mean pore size of 1.85~2.32 nm. The coin cell using water-based binder in the electrolyte of LiPF6 dissolved in mixed organic solvents (EC:DMC:EMC=1:1:1 vol%) showed better capacity than that of oil-based binder. Also, it was found that the coin cell of water-based binder shows an improved cycling performance and coulombic efficiency.

• Korean Chemical Engineering Research
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• 제48권4호
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• pp.440-443
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• 2010

양극인 Co-Mn oxide과 음극인 활성탄, 전해질인 6 M KOH 수용액으로 구성된 혼성 커패시터를 제조하여 cyclic voltammetry를 이용하여 전기화학적 특성을 조사하였다. 제조한 초고용량 커패시터는 0~1.4 V 전위영역에서 안정한 전위창을 나타내며, 주사속도 5 mV/s일 때 비용량 67.3 F/g, 에너지 밀도 18.3 Wh/kg, 출력 밀도는 237.7 kW/kg을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.185-188
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• 2004

A diode structure of field emission lamps based upon carbon-nanotube is studied. The single-walled carbon nanotubes(SWNTs) were produced by arc discharge method. We made the 1-inch diode type flat lamp using CNTs. We applied anode voltage gradually to refine the field emission behavior of emitter in dynamic vacuum system to study the emission current. the brightness and efficiency, etc. The field emission properties was estimated by varying gaps between the cathode and anode, contents of the glass frit. The good luminous efficiency is showed in the gap $900{\mu}m$, $1200{\mu}m$ and contents of the proper glass frit. For the upper conditions, the luminous efficiencies were respectively 23.30, 11.12 1m/W.

• 한국수소및신에너지학회논문집
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• 제22권4호
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• pp.504-511
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• 2011

Nano-sized Sn powder was prepared by pulsed wire evaporation method. The Sn powder and carbon black were charged in jar and ball milled. The milling time was varied with 10 min., 1h, 2h, and 4h, respectively. The milled powders were dried and the shape and size were observed by FE-SEM. Nano-sized Sn powders were plastic-deformed and agglomerated by impact force of balls and heat generated during the SPEX milling. The agglomerated Sn powder also consisted of many nano-sized particles. Initial discharge capacities of milled Sn electrode powders with carbon powder were milled for 10 min., 1h, 2h, and 4h were 787, 829, 827, and 816 mAh/g, respectively. After 5 cycle, discharge capacities of Sn electrode powders with carbon powder milled for 10 min., 1h, 2h, and 4h decreased as 271, 331, 351, and 287 mAh/g, respectively. Because Sn electrode powders milled for 2h constist of uniform and fine size, the cyclability of coin cell made of this powders is better than others.

• 한국전기전자재료학회논문지
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• 제17권5호
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• pp.541-544
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• 2004

Multi- wall carbon nanotubes(MWNTs) were synthesized by thermal chemical vapor deposition. The paste for screen printing was composed of MWNTs, organic vehicle and glass frit. Carton nanotube paste was screen-printed on ITO(indium tin oxide) deposited soda lim을 glass, and then heat treatment was performed. Before the surface treatment, turn on field of derive was 2.6 V/$\mu\textrm{m}$. After the surface treatment, the value was changed into 1.8 V/$\mu\textrm{m}$. The anode current of the derive with 2.83 V/$\mu\textrm{m}$(turn on field) was changed 4 $\mu\textrm{A}$ into 390 $\mu\textrm{A}$ at 1,700 V. Adsorption effect of MWNTs onto phosphor of anode plate was observed by the field emission measurement and resulted in bad effects on properties of devices lifetime and emission lighting.

• 분석과학
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• 제8권4호
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• pp.583-590
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• 1995

Pitch-based mesophase carbon fibers prepared at different temperatures were heat-treated at temperatures lower than those of the preparation and the electrochemical Li doping/undoping characteristics were evaluated in relation to the data of IR, mass, etc. Presence of surface hydroxyls were confirmed by FTIR for lower temperature sample which showed poor anode characteristics. Upon oxidative heating, removal of surface hydroxyls took place, resulting in a remarkable improvement of the electrode characteristics. At the same time, surface roughening took place, which was confirmed by SEM and double layer capacity measurements. In situ mass spectra obesrved during the heat-treatments showed gas evolution of $H_2O$, CO, $CO_2$, $C_2H_4$, and/or $H_2$ depending on the conditions. These data together with those of weight loss and conductivity provided us a valuable information in regard to the evaluation of the electrochemical characteristics.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.852-856
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• 2011

The lithium ion diffusion coefficients of bare, carbon-coated and Cr-doped $LiFePO_4$ were obtained by fitting the discharge curves of each half cell with Li metal anode. Diffusion losses at discharge curves were acquired with experiment data and fitted to equations. Theoretically fitted equations showed good agreement with experimental results. Moreover, theoretical equations are able to predict lithium diffusion coefficient and discharge curves at various discharge rates. The obtained diffusion coefficients were similar to the true diffusion coefficient of phase transformation electrodes. Lithium ion diffusion is one of main factors that determine voltage drop in a half cell with $LiFePO_4$ cathode and Li metal anode. The high diffusion coefficient of carbon-coated and Cr-doped $LiFePO_4$ resulted in better performance at the discharge process. The performance at high discharge rate was improved much as diffusion coefficient increased.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권6호
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• pp.328-334
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• 2000

A lithium ion secondary battery using carbon as a negative electrode has been developed. Further improvements to increase the cell capacity are expected by modifying the structure of the carbonaceous material. There are hopes for the development of large capacity lithium ion secondary batteries with long cycle, high energy density, high power density, and high energy efficiency. In the present paper, needle cokes from petroleum were examined as an anode of lithium ion secondary battery. Petroleum cokes, MCL(Molten Caustic Leaching) treated in Korea Institute Energy Research, were carbonized at various temperatures of 0, 500, 700, $19700^{\circ}C$ at heating rate of $2^{\circ}C$/min for lh. The electrolyte was used lM liPF6 EC/DEC (1:1). The voltage range of charge & discharge was 0.0V(0.05V) ~ 2.0V. The treated petroleum coke at $700^{\circ}C$ had an initial capacity over 560mAh.g which beyond the theoretical maximum capacity, 372mAh/g for LiC6. This phenomena suggests that carbon materials with disordered structure had higher cell capacity than that the graphitic carbon materials.

• Korean Chemical Engineering Research
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• 제62권1호
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• pp.99-104
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• 2024

본 연구에서는 고용량 리튬이온배터리용 음극 소재로 탄소 코팅된 할로우 구조의 실리콘(HSi/C) 복합소재를 제조하였다. CTAB (N-Cetyltrimethylammonium bromide)이 첨가된 Stöber법을 통해 할로우 실리카(HSiO₂)를 합성하였으며, HSiO₂를 마그네슘열 환원한뒤 표면에탄소를 코팅하여 HSi/C 음극복합소재를 제조하였다. 복합소재의물리적 특성과 전기화학적 특성을 CTAB 조성에 따라 조사하였다. FE-SEM 분석 결과 CTAB 조성이 감소할수록 HSiO₂ 입자의 크기가 커졌으나 두께는 감소하였다. 제조된 HSi/C 소재는 다양한 CTAB 비율(0.5, 1.0, 1.5)에서 각각 2188.6, 2164.5, 1866.7 mAh/g의 높은 초기 방전용량을 나타내었으며, 100 사이클의 충·방전 후 0.5-HSi/C가 1171.3 mAh/g의 높은 가역 용량과 70.9%의 용량 유지율을 보여주었다. 전기화학 임피던스 분광법(Electrochemical Impedance Spectroscopy, EIS)으로 저항 특성을 분석하였으며, 0.5-HSi/C 소재가 20 사이클 이후 다른 CTAB 조성의 HSi/C 복합소재에 비해 안정적인 저항 특성을 보이는 것을 확인하였다.