Elucidating the Role of Copper as Redox Additive and Dopant on the Performance of PANI based Supercapacitor

In this article, the role of copper (Cu) as a redox additive and dopant on the performance of Polyaniline (PANI) based supercapacitor was thoroughly investigated. The electrochemical properties of PANI in H2SO4, H2SO4+CuSO4 and Cu doped PANI in H2SO4 were studied using Cyclic Voltammetry (CV) and Impedance Spectroscopy (IS). The CV result indicates that the capacity of PANI in H2SO4 was significantly improved with the introduction of Cu 2+ ions to the electrolyte; yet appearing unstable because of under potential deposition of copper over PANI surface and relatively irreversible nature of redox reaction. However, a stable and improved performance was obtained for Cu doped PANI due to the combined effect of an increase in conductivity and the surface modification of PANI film. For Cu doped PANI, nearly ~2.4 and ~1.5 fold improved interfacial capacitance was achieved than that of PANI (H2SO4) and PANI (H2SO4+CuSO4) respectively. The obtained Nyquist spectra for all the configurations was analysed using an equivalent circuit to understand the fundamentals of capacitive and resistive response of the supercapacitor. The IS measurement leads to direct determination of parameter like series resistance, rate capability of electrode, ion diffusion phenomena and interfacial capacitance. The experimental results and their analysis will have Page 1 of 30 Physical Chemistry Chemical Physics P hy si ca lC he m is tr y C he m ic al P hy si cs A cc ep te d M an us cr ip t