• 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.

• 한국세라믹학회지
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• 제45권8호
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• pp.493-496
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• 2008

Composite electrodes consisting of $CoMnO_2$ and carbon nanofibers(vapor grown carbon nanofiber, VGCF) with high electrical conducivity($CoMnO_2$/VGCF) were prepared on a porous nickel foam substrate as a current collector and their supercapacitive properties were investigated using cyclic voltammetry in 1 M KOH aqueous solution. The $CoMnO_2$/VGCF electrode exhibited high specific capacitance value of 630 F/g at 5 mV/s and excellent capacitance retention of 95% after $10^4$ cycles, indicating that the used VGCF played the important roles in reducing the interfacial resistance in the composite electrode to improve supercapacitive performance.

• 한국분말재료학회지
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• 제28권6호
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• pp.470-477
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• 2021

Energy storage systems should address issues such as power fluctuations and rapid charge-discharge; to meet this requirement, CoFe₂O₄ (CFO) spinel nanoparticles with a suitable electrical conductivity and various redox states are synthesized and used as electrode materials for supercapacitors. In particular, CFO electrodes combined with carbon nanofibers (CNFs) can provide long-term cycling stability by fabricating binder-free three-dimensional electrodes. In this study, CFO-decorated CNFs are prepared by electrospinning and a low-cost hydrothermal method. The effects of heat treatment, such as the activation of CNFs (ACNFs) and calcination of CFO-decorated CNFs (C-CFO/ACNFs), are investigated. The C-CFO/ACNF electrode exhibits a high specific capacitance of 142.9 F/g at a scan rate of 5 mV/s and superior rate capability of 77.6% capacitance retention at a high scan rate of 500 mV/s. This electrode also achieves the lowest charge transfer resistance of 0.0063 Ω and excellent cycling stability (93.5% retention after 5,000 cycles) because of the improved ion conductivity by pathway formation and structural stability. The results of our work are expected to open a new route for manufacturing hybrid capacitor electrodes containing the C-CFO/ACNF electrode that can be easily prepared with a low-cost and simple process with enhanced electrochemical performance.

• 공업화학
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• 제26권3호
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• pp.239-246
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• 2015

나노 탄소재료를 복합화하면 기존 재료의 특성을 유지하면서 그 효율을 극대화할 수 있다. 여기에 이종원소를 부가하면 전기화학적인 특성이 디자인되므로, 나노 탄소재료의 복합화를 통해 한 종류의 나노 재료로부터 여러 강점을 얻을 수 있다. 특히 탄소나노섬유와 금속산화물을 복합화하면 탄소나노섬유의 전기이중층 뿐만 아니라 금속산화물의 산화 환원 반응을 이용하여 비축전 용량, 고율 특성, 수명 특성이 향상되고 높은 수준의 출력밀도가 유지되는 고용량 슈퍼 캐퍼시터용 전극 소재를 개발할 수 있다. 본 총설에서는 탄소의 고출력특성과 금속산화물의 고에너지 특성이 동시에 발현되는 금속산화물계 탄소나노섬유복합체의 제법과 응용에 대한 최신연구를 다루도록 하겠다.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 The Korea-Japan Joint Symposium
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• pp.69-70
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• 2003

10 wt.% of PAN was dissolved in N,N-dimethylformamide (DMF) and 1 wt. % of the multi wall carbon nanotubes (MWCNTs) was evenly dispersed in PAN solution by using ultrasonic miner. The 1 wt.% addition of MWCNT increased the specific capacitance by two times more from 82 to 160 F/g. The specific capacitance of carbon nanofiber(CNF)/carbon nanotube(CNT) composite capacitors was about 90 F/g at the current density of 500 mA/g. This value is even larger than the capacitance from the CNF electrode at the current density of 5 mA. The relatively high capacitance at the high current density is a practical importance for applications to supercapacitor in motor vehicle.

• Korean Chemical Engineering Research
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• 제46권1호
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• pp.94-98
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• 2008

비정형 $MnO_2$의 초고용량 캐폐시턴스 특성을 향상시키기 위하여 망간산화물을 높은 전기전도를 갖는 나노탄소섬유(vapour-grown carbon nanofibers, VGCF)와 복합화하여 나노탄소섬유/망간 산화물(VGCF(40 wt%)/$MnO_2$) 복합 전극을 제조하여 cyclic voltammetry(CV), impedance spectroscopy 및 chronopotentiometric charge/discharge 기법을 사용하여 1.0M $Na_2SO_4$ 전해질에서 초고용량 캐폐시터 특성을 조사하였다. 40 wt% VGCF를 포함한 복합전극에서 $0.8mg/cm^2$ 망간산화물을 로딩한 $VGCF/MnO_2$ 복합전극은 주사속도 20 mV/s에서는 380 F/g, 500 mV/s에서는 230 F/g의 비용량 값을 나타냈다. 또한, $2.0mA/cm^2$의 일정전류로 충방전 실험을 수행한 결과 3,000회에서 97%의 초기용량을 유지하였다.

• Carbon letters
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• 제11권1호
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• pp.38-40
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• 2010

Carbon supported electrocatalysts are commonly used as electrode materials for polymer electrolyte membrane fuel cells(PEMFCs). These kinds of electrocatalysts provide large surface area and sufficient electrical conductivity. The support of typical PEM fuel cell catalysts has been a traditional conductive type of carbon black. However, even though the carbon particles conduct electrons, there is still significant portion of Pt that is isolated from the external circuit and the PEM, resulting in a low Pt utilization. Herein, new types of carbon materials to effectively utilize the Pt catalyst are being evaluated. Carbon nanofiber/activated carbon fiber (CNF/ACF) composite with multifunctional surfaces were prepared through catalytic growth of CNFs on ACFs. Nickel nitrate was used as a precursor of the catalyst to synthesize carbon nanofibers(CNFs). CNFs were synthesized by pyrolysising $CH_4$ using catalysts dispersed in acetone and ACF(activated carbon fiber). The as-prepared samples were characterized with transmission electron microscopy(TEM), scanning electron microscopy(SEM). In TEM image, carbon nanofibers were synthesized on the ACF to form a three-dimensional network. Pt/CNF/ACF was employed as a catalyst for PEMFC. As the ratio of prepared catalyst to commercial catalyst was changed from 0 to 50%, the performance of the mixture of 30 wt% of Pt/CNF/ACF and 70wt% of Pt/C commercial catalyst showed better perfromance than that of 100% commercial catalyst. The unique structure of CNF can supply the significant site for the stabilization of Pt particles. CNF/ACF is expected to be promising support to improve the performance in PEMFC.

• Composites Research
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• 제23권3호
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• pp.31-36
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• 2010

서로 다른 CNF(탄소 나노섬유) 함유량을 가진 신 재료인 CNF/폴리피롤(PPy) 복합재료 필름들이 세계 최초로 화학적 전해 중합법으로 제조 되었다. 기존의 물리적 혼합법으로 제조된 필름과 비교하면 재료의 유연성이 매우 증가하였다. 복합재료와의 비교를 위해서 순수 폴리피롤 필름 역시 전해중합 방법으로 제조되었다. 전자주사현미경(SEM)으로 재료 샘플의 전극면, 용액면, 단면을 각각 촬영하여 그 재료 특성을 분석하였다. 각 복합재료 샘플의 전기전도성은 4점 탐침법으로 측정 되었다. 각 필름의 전도성은 두께가 0.013cm인 순수 PPy 필름은 79.33S/cm, 두께가 0.018cm이고 CNF 함유량 5% CNF/PPy 필름은 93S/cm, 두께가 0.017cm이고 CNF 함유량 10% CNF/PPy 필름은 126S/cm으로 측정되었다. CNF의 함유량이 증가할수록 PPy의 전도성이 크게 증가하는 것으로 확인되었으며, CNF/PPy 복합재료의 좋은 전도성은 소형의 굽힘 작동기로 사용될 수 있는 가능성을 높인다. 이를 입증하기 위해서 공기 중에서 작동 가능한 PPy 굽힘 센서를 설계하여 유한요소법으로 해석하였다.