High performance hybrid supercapacitor based on two nanostructured conducting polymers: Self-doped polyaniline and polypyrrole nanofibers

A hybrid asymmetric electrochemical supercapacitor is constructed by employing two different nanostructured conducting polymers of polypyrrole (PPy) and self-doped polyaniline (SDPA). Different electrochemical methods, including cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy (EIS), are performed to characterize the electrochemical performance of the supercapacitor. The maximal working potential window of 1.3 V is associated with more than 97 F g−1 of total electrode materials. The cell maintains approximately 70% of its initial capacitance after 1000 cycles with an equivalent series resistance (ESR) below 1.6 Ω cm2. Furthermore, the system shows high specific energy, specific power and maximum power values of 22.87 Wh kg−1, 570 W kg−1 and 45,193 W kg−1, respectively, at a current density of 5 mA cm−2 in 1 M KCl. Long-life cycling is achieved by removing dissolved oxygen and using a mild pH electrolyte, which limits the redox activity of the electrically conducting polymers (ECPs). Moreover, the proposed supercapacitor exhibits high capacitance retention of 89% at a higher current density (40 mA cm−2), indicating good electrochemical stability and rate capability. The performance of the proposed hybrid supercapacitor has been compared with two other symmetric cells.

► A high performance asymmetric hybrid supercapacitor was prepared in aqueous media with a working voltage up to 1.3 V.
► Using SDPA allowed for the use of solutions at a mild pH.
► The use of mild pH solutions caused less degradation and good electrochemical stability of the conducting polymer as the active material.