Statistical Study of the Influence of Electrosynthesis Conditions on the Capacitance of Polypyrrole

Polypyrrole (PPy) is a promising material for the fabrication of flexible energy storage devices and much research has been published. However, no statistical tools have been used to relate PPy synthesis conditions to its energy storage performance, considering not only the main synthesis factors but also their interactions. In this work, we use a factorial design of experiments to evaluate the influence of two electropolymerization methods and three synthesis parameters on the energy storage capacity of PPy coatings. The polymers were characterized by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), electrochemical impedance spectroscopy (EIS), Raman spectroscopy, and scanning electron microscopy (SEM). Statistical tests showed that ClO₄ ^--doped PPy exhibits higher capacitances than p-toluenesulfonate (pTS)-doped PPy, with a maximum capacitance of 353.75 ± 1.6 F g^-1 at 1 A g^-1. However, the pTS-doped PPy had better cycling stability, losing only 10% of its original energy storage capability after 5000 charge-discharge cycles at 1 A g^-1. The best energy densities and power densities were 49.1 ± 0.2 Wh kg^-1 and 2297 ± 15 W kg^-1 (ClO₄ ^--doped PPy) and 47.8 ± 1.5 Wh kg^-1 and 2191 ± 91 W kg^-1 (pTS-doped PPy), respectively, which indicates that through statistical tools, the optimal synthesis conditions are refined to take advantage of the energy storage properties of this polymer.