Korean Chemical Engineering Research, Vol.46, No.1, 94-98, February, 2008
나노탄소섬유/MnO2 복합전극의 초고용량 캐폐시터 특성
Supercapacitive Properties of Carbon-Nano Fiber/MnO2 Composite Electrode
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초록
비정형 MnO2의 초고용량 캐폐시턴스 특성을 향상시키기 위하여 망간산화물을 높은 전기전도를 갖는 나노탄소섬유 (vapour-grown carbon nanofibers, VGCF)와 복합화하여 나노탄소섬유/망간 산화물(VGCF(40 wt%)/MnO2) 복합 전극을 제조하여 cyclic voltammetry(CV), impedance spectroscopy 및 chronopotentiometric charge/discharge 기법을 사용하여 1.0M Na2SO4 전해질에서 초고용량 캐폐시터 특성을 조사하였다. 40 wt% VGCF를 포함한 복합전극에서 0.8 mg/cm2 망간산화물을 로딩한 VGCF/MnO2 복합전극은 주사속도 20 mV/s에서는 380 F/g, 500 mV/s에서는 230 F/g의 비용량 값을 나타냈다. 또한, 2.0 mA/cm2의 일정전류로 충방전 실험을 수행한 결과 3,000회에서 97%의 초기용량을 유지하였다.
In order to improve the specific capacitance of amorphous hydrous manganese oxide (MnO2) for supercapacitors, it is made into composites with vapour-grown carbon nanofibers (VGCF) having the VGCF ratio as 40 wt% in the composites. The electrochemical properties of these composites are investigated in 1.0 M Na2SO4 by cyclic voltammetry (CV), impedance measurements and chronopotentiometric charger/discharger. The composite with 40 wt% VGCF shows the superior electrochemical performance, whose specific capacitance (based on the mass of MnO2, 0.8 mg/cm2) is 380 F/g at 20 mV/s and 230 F/g at 500 mV/s. Also, the cycle-life testing of this electrode carried out for 3,000 charge/discharge cycles at 2.0 mA/cm2 shows 97% capacitance retention.
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