Solid-state responses of electrochemically deposited polyaniline and polypyrrole-based symmetric supercapacitors in different pH conditions

This work elucidates the fabrication and electrochemical performance of solid-state symmetric supercapacitors based on polyaniline and polypyrrole films synthesized through electrochemical deposition. The study systematically investigates the impact of electrolyte pH on the performance of these devices, comparing responses in acidic, neutral, and alkaline environments. The polyaniline-based device demonstrates a superior response in acidic electrolyte conditions, which is attributed to the protonation/deprotonation mechanisms inherent in the polymer matrix, a phenomenon that is explored and interpreted in the paper. However, the symmetric supercapacitor employing polypyrrole exhibits superior performance in both acidic and alkaline electrolytes, suggesting the pseudocapacitive nature of polypyrrole even in alkaline conditions. The redox behavior of polypyrrole in alkaline environments primarily relies on the exchange of hydroxide ions, facilitating polypyrrole’s superior retention of its redox characteristics compared to polyaniline. The findings contribute to the rational design of solid-state supercapacitors tailored for specific electrolyte conditions, with potential applications in diverse electrochemical energy storage systems.