Facile preparation of polyaniline-carbon nanotube hybrid electrodes and dependence of their supercapacitive properties on degree of carboxylation of carbon nanotubes

This paper reports on the preparation of polyaniline-carbon nanotube (PANi-CNT) hybrid electrodes via a facile electro-co-deposition method. In the process, carboxylated CNTs, which serve as counter anions in the electrodes, are incorporated into PANi. Supercapacitive properties of PANi-CNT hybrid electrodes are observed to depend on the degree of carboxylation of CNTs. Electrochemical measurements show two key results. First, the incorporation of CNTs observably improves the supercapacitive properties of PANi electrodes. Second, the CNTs with higher degree of carboxylation result in further improvement in supercapacitive properties of the hybrid electrodes. The former observation is attributed to the high electrical conductivity and large surface area of CNTs, which improve the electrical conductivities of the hybrids and facilitate the dispersion of PANi. The latter is in line with the fact that more CNTs are incorporated into the hybrids due to higher degree of carboxylation. The PANi-CNT electrodes prepared by CNTs with higher degree of carboxylation demonstrate remarkable supercapacitive performances, including high specific capacitance of 578.2 F g⁻¹ and good rate performance. They also have superior cycling stability, showing 88.2% of capacitance retention after 10,000 cycles.