Understanding the effect of polypyrrole and poly(3,4-ethylenedioxythiophene) on enhancing the supercapacitor performance of NiCo 2 O 4 electrodes

Herein, two of the most well-known conducting polymers (CP), polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT), were coated onto mesoporous NiCo2O4 nanosheet arrays through an efficient and controllable electrodeposition process. We considered such a unique nanostructure to be an ideal model to accurately compare and understand the effects of PPy and PEDOT on electrochemical performances. Comparing the electrochemical performances of NiCo2O4@CP and pure NiCo2O4 electrodes, we found that the NiCo2O4@PPy electrode possesses the highest areal capacitance of 4.1 F cm−2 at 2 mA cm−2, which is significantly higher than the values obtained for the NiCo2O4@PEDOT (0.86 F cm−2) and NiCo2O4 electrodes (0.65 F cm−2). For rate capability, even at a high current density of 30 mA cm−2, an areal capacitance of 2.7 F cm−2 can be achieved for the NiCo2O4@PPy electrode. Moreover, the NiCo2O4@PPy electrode shows considerably smaller equivalent series resistance (ESR) than that of the NiCo2O4@PEDOT and NiCo2O4 electrodes. Therefore, the NiCo2O4@PPy hybrid composites are considered to be ideal supercapacitor electrode materials with enhanced electrochemical performances, which makes them suitable for many practical applications.