Electrochemical Performance of Free-Standing and Flexible Graphene and TiO₂ Composites with Different Conductive Polymers as Electrodes for Supercapacitors

The advantage of using composite electrode materials for energy storage is, to a large extent, the synergistic role of their components. Our work focuses on the investigation of the interactions of each phase, exploring the patterns found with the change of materials to provide theoretical or experimental foundations for future study. Here, conductive polymers (CPs), including polyaniline (PANi), polypyrrole (PPy), and polythiophene (PTh), as well as reduced graphene oxide (rGO), and TiO₂ with the different crystalline phases of anatase and rutile were applied to form a series of free-standing and flexible binary or ternary composite electrodes. The electrochemical behaviors of these composite electrodes are presented. The results indicate that the synergistic improvement in electrochemical performance is due to the incorporation of the different components. CPs significantly increase the current density of these composite films and contribute their pseudocapacitance to improve the specific capacitance, but lead to a decline in cycle stability. After introducing TiO₂ , both the specific capacitance and the cycle-stability of rGO-TiO₂ -CP were synergistically improved. A CP can magnify the pseudocapacitance behavior of any of the TiO₂ crystalline phases, and interactions vary with the specific CP and the specific TiO₂ crystalline phase employed. The synergistic effects of the as-prepared composites were theoretically predicted and explored.