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Keywords:

  • chemical vapor deposition;
  • electrochemical properties;
  • single-walled carbon nanotubes

Abstract

We report the fabrication of vertically aligned single-walled carbon nanotube (VA-SWCNT) electrodes for a symmetric electrochemical capacitor using a simple, low-cost ethanol-based SWCNT growth system. From the CNT direct growth technique, the electrode was easily prepared and consequently assembled with an electrochemically stable ionic liquid as electrolyte. VA-SWCNTs were directly grown on conducting SUS 310S foils in which the binder material was not incorporated in the capacitor structure. The morphology of as-grown CNTs was investigated using scanning and transmission electron microscopy. This capacitor demonstrated a gravimetric capacitance of up to 584 F g−1 (at 1 mV s−1 scan rate) and a high-rate capability, with up to 1000 mV s−1 scan rate being obtained. From the cyclic voltammetric analysis, the capacitance was contributed not only from the ideal double-layer capacitance, but also from faradaic/redox processes that might have occurred during charge–discharge. Other than the capacitance, the VA-SWCNT capacitor electrochemical performance was also measured by using frequency response (electrochemical impedance) and charge–discharge analyses.