Interplay between enhanced charge storage and charge transfer mechanism in Cu doped PANI: The role of surface morphology

• The role of electrode morphology on the charge storage and charge transfer property of supercapacitor is investigated.
• Electro analytical characterization of supercapacitor is achieved through a strategic combination of DC and AC techniques.
• Impedance model is used to elucidate the charge transfer and charge storage in Cu doped polymer electrode.

The present article reports an insight into the interplay between enhanced charge storage and charge transfer mechanism at electrode–electrolyte interface having different electrode morphology. The DC techniques like cyclic voltammetry (CV) and galvanostatic charge discharge (GCD) are employed to obtain the interfacial capacitance and resistance, Faradaic features and charge retention ratio of the electrode–electrolyte interface as a function of applied bias. The porous nanorod morphology of copper doped polyaniline (PANI) delivered a maximum interfacial capacitance of 283 mF/cm2 at 0.5 mA/cm2 with a rate capability of 39%. On the contrary, the compact granular morphology of copper doped PANI delivered the maximum interfacial capacitance of 3.01 mF/cm2 at 0.5 mA/cm2 with a rate capability of 88%. AC technique like Electrochemical Impedance Spectroscopy (EIS) leads to the straight forward determination of charge transfer resistance, double layer capacitance, Warburg coefficient, interfacial capacitance and resistance, and series resistance of the electrode–electrolyte interface.