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Poo Reum Choi,Sang-Gil Kim,Ji Chul Jung,Myung-Soo Kim 한국탄소학회 2017 Carbon Letters Vol.22 No.-
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) precarbonized at 500–1000°C in N2 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°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°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.
Eunji Lee,Soon Hyung Kwon,Poo Reum Choi,Ji Chul Jung,Myung-Soo Kim 한국탄소학회 2015 Carbon Letters Vol.16 No.2
Activated carbons (ACs) were prepared by activation of coal tar pitch (CTP) in the range of 700°C-1000°C for 1-4 h using potassium hydroxide (KOH) powder as the activation agent. The optimal activation conditions were determined to be a CTP/KOH ratio of 1:4, activation temperature of 900°C, and activation time of 3 h. The obtained ACs showed increased pore size distribution in the range of 1 to 2 nm and the highest specific capacitance of 122 F/g in a two-electrode system with an organic electrolyte, as measured by a charge-discharge method in the voltage range of 0-2.7 V. In order to improve the performance of the electric double-layer capacitor electrode, various mixtures of CTP and petroleum pitch (PP) were activated at the optimal activation conditions previously determined for CTP. Although the specific capacitance of AC electrodes prepared from CTP only and the mixtures of CTP and PP was not significantly different at a current density of 1 A/g, the AC electrodes from CTP and PP mixtures showed outstanding specific capacitance at higher current rates. In particular, CTP-PP61 (6:1 mixture) had the highest specific capacitance of 132 F/g, and the specific capacitance remained above 90% at a high current density of 3 A/g. It was found that the high specific capacitance could be attributed to the increased micro-pore volume of ACs with pore sizes from 1 to 2 nm, and the high power density could be attributed to the increased meso-pore volume.
K<sub>2</sub>CO<sub>3</sub> 처리된 Coal Tar Pitch 활성탄 전극의 결정성 및 EDLC 성능
최푸름,정지철,임연수,김명수,Choi, Poo Reum,Jung, Ji Chul,Lim, Yun-Soo,Kim, Myung-Soo 한국재료학회 2016 한국재료학회지 Vol.26 No.9
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.
KOH 활성화에 의한 피치계 고품질 활성탄의 제조 및 특성
이은지,권순형,최푸름,우종표,정지철,김명수,Lee, Eun-Ji,Kwon, Soon-Hyung,Choi, Poo-Reum,U, Jong-Pyo,Jung, Ji-Chul,Kim, Myung-Soo 한국응용과학기술학회 2014 한국응용과학기술학회지 Vol.31 No.3
In order to prepare high-quality activated carbons (ACs), coal tar pitch (CTP), and mixtures of CTP and petroleum pitch (PP) were activated with KOH. The ACs prepared by activation of CTP in the range of $700{\sim}1000^{\circ}C$ for 1~5 h had very porous textures with large specific surface areas of $2470{\sim}3081m^2/g$. The optimal activation conditions of CTP were determined as CTP/KOH ratio of 1:4, activation temperature of $900^{\circ}C$, and activation time of 3 h. The obtained AC showed the highest micro-pore volume, and pretty high specific surface area and meso-pore volume. The micro-pore volumes and specific areas of activated mixtures of CTP and PP were similar to each other but the meso-pore volume could be increased. In order to change the degree of crystallinity of precursors before KOH activation process, the CTPs were carbonized in the range of $500{\sim}900^{\circ}C$. As the carbonization temperature increased, the specific surface area and pore volume of the activated ACs with the same activation conditions for CTP decreased dramatically. It was demonstrated that the increased pore size distribution of AC electrodes in the range of 1 to 2 nm plays an important role in the performance of electric double-layer capacitor.
GPU Based Feature Profile Simulation for Deep Contact Hole Etching in Fluorocarbon Plasma
Yeon-Ho Im,Won-Seok Chang,Kwang-Sung Choi,Dong-Hun Yu,Deog-Gyun Cho,Yeong-Geun Yook,Poo-Reum Chun,Se-A Lee,Jin-Tae Kim,Deuk-Chul Kwon,Jung-Sik Yoon,Dae-Woong Kim,Shin-Jae You 한국진공학회 2012 한국진공학회 학술발표회초록집 Vol.2012 No.8