Carbon Nanotubes Supported Conducting Polymer Electrode for Supercapacitor

Supercapacitors (SCs) as portable systems and electric vehicles have aroused great interest due to their high power in short term. The composite materials of carbon nanotubes and conducting polymers have been considered for SC electrodes. Carbon nanotubes (CNTs), due to their outstanding electric properties and nanoscale texture, such as large specific area, low cost, and cycle stability, exhibit a large and stable double layer capacitance. However, the pure CNTs have low specific capacitance and relatively poor energy density, which limit the commercial application for SCs. On the other hand, conducting polymers have been intensively investigated as the electrode material in SCs. Higher electrical conductivity, larger pseudo‐capacitance, and faster doping/dedoping rate during charge/ discharge process are their main advantages. The possible application of conducting polymers in SCs is dictated by their significant capacitance values and huge faradaic capacitance. They undergo a redox reaction to store charge in the bulk of the material and thereby increase the energy stored and reduce self‐discharge. But they are not ideal materials used alone as advanced capacitors materials, because of their low mechanical strength, poor electrical conductivity and low porosity. This chapter looks at the major conducting polymer materials, namely, polyaniline, polypyrrole, and ethylene‐evinyl acetate copolymer, as well as composites of these materials with CNTs. These composites of the CNTs with these electroactive species propose a facile solution to the capacitance limitation of the CNTs and the structural defects of these electroactive species. In order to achieve low contact resistance and high surface area, surface activation through dispersion or ordered assembling of CNTs have been investigated.