Enhanced electrochemical performances of PANI using redox additive of K4[Fe(CN)6] in aqueous electrolyte for symmetric supercapacitors

• Effect of K4[Fe(CN)6] in H2SO4 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−1 at 1 mA cm−2 in K4[Fe (CN)6] added 1 M H2SO4.
• PANI-1 symmetric supercapacitor shows almost 100% of capacity retention.

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/H2SO4 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 H2SO4 and 0.08 M K4[Fe(CN)6] added 1 M H2SO4 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 K4[Fe(CN)6]) delivered an enhanced specific capacitance of 228 F g−1 (∼912 F g−1 for single electrode) than that of 1 M H2SO4 (100 F g−1) at 1 mA cm−2. Further cycling stability is performed at 5 mA cm−2 ensures the durability of the supercapacitor.

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