Abstract:
Vertically Aligned Carbon Nanotubes (VACNTs)-coated fexible aluminium (Al) foil is studied as an electrode for supercapacitor applications. VACNTs are grown on Al foil inside thermal Chemical Vapor Deposition (CVD) reactor. 20 nm
thick layer of Fe is used as a catalyst while Ar, H2 and C2H2 are used as precursor gases. The efect of growth temperature
on the structure of CNTs is studied by varying the temperature of CVD reactor from 550 °C to 625 °C. Better alignment of
VACNTs arrays on Al foil is recorded at 600 °C growth temperature in comparison to other processing temperatures. Cyclic
voltammetry results shows that VACNTs-coated Al foil has a specifc capacitance of~3.01 F/g at a scan rate of 50 mV/s.
The direct growth of VACNT array results in better contact with Al foil and thus low ESR values observed in impedance
spectroscopy analysis. This leads to a fast charge–discharge cycle as well as a very high value of power density (187.79 kW/
kg) suitable for high power applications. Moreover, wettability study shows that the fabricated VACNT electrode has a contact
angle of more than 152° which signifes that it is a superhydrophobic surface and hence shows lower specifc capacitance in
comparison to reported values for VACNT array. Therefore, it is necessary to develop suitable post-processing strategies to
make VACNTs hydrophilic to realize their full potential in supercapacitor applications.
