Electrochemical capacitance of a nanoporous composite of carbon nanotubes and polypyrrole

This work reports the supercapacitive properties of electrochemically grown composite films of multiwalled carbon nanotubes (MWNT) and polypyrrole (PPy), a conducting polymer. Scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy revealed that the nanoporous three-dimensional arrangement of PPy-coated MWNTs in these films facilitated improved electron and ion transfer relative to pure PPy films. The low-frequency capacitance was measured for films of varying thickness, revealing specific capacitances per mass (C(mass)) and geometric area (C(area)) as high as 192 F g(-1) and 1.0 F cm(-2), respectively. Rates of charge and discharge about an order of magnitude faster than similarly prepared pure PPy films were also observed.