Influence of heat treatment and electrochemical treatment on the properties of PANI electrodeposited on carbon fiber felt

Energy storage devices such as supercapacitors with flexible electrodes are used in new technologies of the modern printed electronics system. These flexible energy stores can power systems containing chips, microcontrollers and others. For the development of these flexible electrodes, carbon fiber felt (current collector) with polyaniline (active material) form a composite material with high performance of transport and storage of charges, lightness and flexibility. So, to obtain an electrochemical performance of the electrode, in this work the carbon fiber surface was modified by thermal and electrochemical treatment (insertion of heteroatoms of oxygenated groups in the fiber) to enhance conductivity and the anchor of the polyaniline, respectively. After the carbon fiber felt underwent heat treatment at temperatures of 1250 °C, 1500 °C and 1900 °C, half of the fiber felt samples underwent a chronoamperometric activation process in a sulfuric acid at 1 mol L−1. Subsequently, polyaniline was electrodeposited onto the fibers via square wave voltammetry, and the materials were characterized by: scanning electron microscopy (SEM), X-ray diffraction (XRD), cyclic voltammetry (CV), electrochemical impedance spectrometry (EIS) and Raman scattering. The composite in which the fiber was thermally treated at 1250 °C without electrochemical activation obtained a specific capacitance of 386.6 F g−1. The carbon fiber treated at higher temperature (1900 °C) and with electrochemical functionalization, obtained improved electrolyte/electrode interaction, which favored the PANI electrodeposition and specific capacitance (345.1 F g−1).