Investigation of polyaniline films doped with Co2+ as the electrode material for electrochemical supercapacitors

H+ and Co2+ ions co-doped polyaniline were synthesized by cyclic voltammetry onto the stainless steel mesh with various concentrations of cobalt chloride (CoCl2 · 6H2O) in electrolyte. The structure and morphology of polyaniline (PANI) and PANI/Co2+ films were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) techniques. The electrochemical properties of PANI and PANI/Co2+ films were investigated by cyclic voltammetry, galvanostatic charge–discharge test, and electrochemical impedance spectroscopy (EIS) in 0.5 mol L−1 H2SO4 electrolyte in a three-electrode system. The PANI/0.3 M Co2+ film shows a larger specific capacitance of 736 F g−1 at a current density of 3 mA/cm2 and lower resistance compared with the pure PANI film. The results indicated that the PANI/Co2+ films are promising material for supercapacitors.