Montmorillonite/Poly(Pyrrole) for Low-Cost Supercapacitor Electrode Hybrid Materials

Conductive polymers such as polypyrrole have been widely used as pseudo-capacitive electrodes for supercapacitors. This work demonstrates a simple method to improve the performance of conductive polymer electrodes by adding montmorillonite in order to perform capacitive behavior. Conductive composite polymers (CCPs) based on montmorillonite/polypyrrole (MMT/PPy(Cl)) have been synthesized by polymerization using FeCl₃ as an oxidizing agent. During the preparation of CCP, the effect of MMT/pyrrole mass ratio and the influence of the amount of added H⁺ and temperature of the synthesis medium on the electrochemical performance of the composite have been investigated. The investigation associated with conductivity measurement allowed us to determine the best conditions to reach a high specific capacitance of 465 F gr^-1 measured by cyclic voltammetry with respect to the CCP synthesized at ambient temperature (220 F gr^-1) and a 35% increase in capacity compared to its homologue synthesized in neutral conditions at a low temperature. These performances have been advantageously correlated both to the edge acidity of the host material and to the evolution of its conductivity according to the preparation conditions. The galvanostatic charge/discharge tests also confirm the stability of the obtained composite, and a capacitance of 325 F g^-1 for the best CCP is recorded with a regime of 1 A g^-1. In addition, the durability of the device shows that the proposed material has a relatively good stability during cycling.