Tuning electrochemical performance of polyaniline-based supercapacitors by inclusion of protonic acid and electrolyte concentration

This study investigates the role of inclusion of protonic acid (HCl, H₂SO₄) and optimized electrolyte concentration of KOH and NaOH to enhance the efficiency of the PANI as a supercapacitor electrode. Electrochemical testing of PANI doped with HCl and H₂SO₄ reveals a clear performance distinction in different electrolyte concentrations. PANI doped with 1 M HCl (PH1) exhibits an outperforming specific capacitance of 167.75 Fg^-1 in 1 M KOH electrolyte than 1 M H₂SO₄ doped PANI (PS) with specific capacitance of 155.75 Fg^-1 under same condition. Furthermore, the significant enhancement in specific capacitance of the order of 256 Fg^-1 at 1 Ag^-1 (current density) is shown by PH1 with 6 M concentration of KOH. X-ray diffraction (XRD) analysis confirms semi-crystalline nature of PANI, with a shift toward a higher angle upon doping indicating the enhanced charge storage capacity and improved stability. The enhancement in electrochemical properties is further supported by FESEM analysis where polyaniline nanoparticles doped with 2 M HCl (PH2) shows agglomeration, while doping with 1 M H₂SO₄ and HCl exhibits a well-aligned nanofiber morphology. The current findings of present work highlight that, how important the role of optimization is for selecting suitable concentration of dopants as well as electrolytes to develop high-performance PANI-based electrodes for advancing high-performance supercapacitors.