Fabrication and Characterization of Polypyrrole/Reduced Graphene-Oxide Films for Electrochemical Capacitors

Abstract

The co-electrodeposition and characterization of Polypyrrole (PPy)/Reduced Graphene Oxide (RGO) films (1:5, 1:10 and 1:15 mass ratio) for electrochemical capacitors are presented in this work. Polypyrrole polymerization and incorporation of RGO were conducted simultaneously in order to attain the best possible dispersion of the latter within the polypyrrole matrix. The materials were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and electrochemical impedance spectroscopy (EIS). The effect of the RGO:PPy mass ratio on the film electrochemical and morphological properties was evaluated. The results show a good dispersion of RGO was attained, along with a good cycling stability of the composite materials. Agglomeration of the PPy was however observed. EIS analysis showed the composite capacitance increases as the RGO content is increased. The polarization resistance, on the other side, increased unexpectedly for larger PPy contents due mainly to agglomeration effects and over-oxidation of the conductive polymer. A finer dispersion of the PPy phase is imperative to improve the electrochemical properties of the composite.

Effect of Deposition Parameters on Electrochemical Properties of Polypyrrole-Graphene Oxide Films

“…The lower current obtained in the presence of GO was due to its low conductivity [24]. As the area of the cyclo voltammogram indicates the loading with active material [11], it was observed that the coatings contained less active material upon the addition of GO by CV deposition. The galvanostatic co-electrodeposition results confirmed the increased voltage necessary for deposition when GO is added.…”

“…The combination of materials such as conducting polymers with carbon nanomaterials has attracted increased interest in the last years in order to overcome the drawbacks these materials have as a singular component and improve their properties by synthesizing a hybrid material with a synergetic effect on properties including high energy and power density, cyclability [5], and stability [11]. For example, polypyrrole (PPy) is one of the most used conjugated polymers [10] in energy storage application [4], of an anionic surfactant could be employed to interact with the carboxyl groups of GO and separate layers of GO to exhibit improved performance [23].…”

“…Amongst such methods, electrochemical deposition is an easy, cheap, rapid, and simple method [21] which allows the fabrication of PPy/rGO composites without the necessity of other chemical binders [22]. Moreover, electrodeposition allows a high degree of control on the morphology, aspect ratio, and performance of coatings by simply varying the deposition conditions including deposition cycles [21], pH, potential, and temperature [11], so that good electrical connection and low internal resistance coatings are achieved [18]. The marked influence of GO on the morphology of the PPy/rGO hybrids with respect to its concentration has been reported as the nucleation sites for PPy growth are adjusted [16].The loading of active material can be controlled by electrodeposition parameters such as deposition duration [6], deposition charge density [20], the applied potential or precursor concentration [13].…”