Supercapacitors from nanotubes/polypyrrole composites

A novel type of composite electrode based on multiwalled carbon nanotubes (MWNTs) coated with polypyrrole (PPy) has been used in supercapacitors. A homogeneous layer of PPy has been deposited on the nanotubular materials by electrochemical polymerization of pyrrole, that in all cases enhances the specific capacitance. A maximum value of 163 F/g has been obtained for MWNTs prepared at 600 °C and modified by a PPy layer of 5 nm, whereas it is only 50 F/g for the pristine nanotubes. The open entangled network of the nanocomposite favors the formation of a three-dimensional electrical double layer allowing a more effective contribution of the pseudofaradaic properties of PPy.