Evolution of polypyrrole electrode during electropolymerization and its effect on energy storage performance

Abstract This study investigates the influence of electropolymerization time on the evolution of morphology and the electrochemical performance of polypyrrole (PPy) electrodes. The PPy films were synthesized by varying the deposition time from 300 seconds to 1800 seconds, corresponding to 5 to 50 cycles. The electrodes were characterized by Raman spectroscopy, XPS, and SEM, and electrochemical analyses were conducted using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD). Experimental results showed that increasing deposition time yields large cauliflower-like structures, thereby enhancing capacitance. The 50 cycle electrode exhibited the highest specific capacitance of 412 F/g in a three-electrode configuration using 1.2 M KCl aqueous electrolyte. The EIS analysis revealed a low ohmic resistance and increasing non-ohmic resistance with deposition, which may indicate the onset of diffusion-limited behavior. A symmetric PPy supercapacitor assembled using optimized electrodes delivered an energy density (ED) of 10.29 Wh/kg and power density (PD) of 146 W/kg at 0.1 A/g. These findings show that electrodeposition time plays an important role in PPy film growth, ion transport, and the resulting electrochemical performance.