Enhanced electrochemical performances of PANI using redox additive of K{sub 4}[Fe(CN){sub 6}] in aqueous electrolyte for symmetric supercapacitors

Highlights: • Effect of K{sub 4}[Fe(CN){sub 6}] in H{sub 2}SO{sub 4} studied on the electrochemical properties of PANI. • The polaron band – π* transition reveals the emeraldine salt (conductive) form. • CV curves exhibit quasi-reversible redox behavior. • Symmetric PANI SC shows 228 F g{sup −1} at 1 mA cm{sup −2} in K{sub 4}[Fe (CN){sub 6}] added 1 M H{sub 2}SO{sub 4}. • PANI-1 symmetric supercapacitor shows almost 100% of capacity retention. - Abstract: Polyaniline (PANI) particles were prepared by reflux assisted chemical oxidative polymerization method with the aid of ammonium per sulfate/ferric chloride as oxidants and HCl/H{sub 2}SO{sub 4} as the medium. Amorphous nature and the emeraldine state of PANI were revealed from X-ray diffraction and Fourier transform infrared analysis. Moreover, ultra violet–visible spectra attributes to the polaron band – π* transition of polyaniline. The scanning electron microscopic image shows that the particle size is in the range of 0.2–2 μm. The electrochemical performances of the material were investigated in 1 M H{sub 2}SO{sub 4} and 0.08 M K{sub 4}[Fe(CN){sub 6}] added 1 M H{sub 2}SO{sub 4} aqueous electrolytes. Cyclic voltammetry and galvanostatic charge–discharge studies were carried out to find its suitability as a supercapacitor electrode material. The charge discharge analysis of the fabricated symmetric supercapacitors revealed the fact that the electrolyte containing redox additive (0.08 M K{sub 4}[Fe(CN){sub 6}]) delivered an enhanced specific capacitance of 228 F g{sup −1} (∼912 F g{sup −1} for single electrode) than that of 1 M H{sub 2}SO{sub 4} (100 F g{sup −1}) at 1 mA cm{sup −2}. Further cycling stability is performed at 5 mA cm{sup −2} ensures the durability of the supercapacitor.