Conducting Polymer-Metal-Based Binary Composites for Supercapacitor Applications

Abstract

Among the various energy-storage systems available, supercapacitors possess excellent characteristics, for instance, long cycle life, high energy and power density, likewise wide thermal operating range. There are two types of electrode materials to store the charge based on the mechanisms. First mechanism includes carbon-based active materials such as quantum dots, carbon nanotubes, which follow electrical double-layer (EDLC) mechanism. Second, metal oxides (MOs) or conducting polymers (CPs) and their nanocomposites, which undergo redox reactions called pseudo capacitance. For example, polyaniline (PANI), polypyrrole (PPy), metal oxides, and hydroxides such as TiO2, ZnO2, NiO, MnO2, Ni(OH)2, SnO2 Fe2O3 and Fe3O4. These nanomaterials can be used as efficient electrode materials because of their redox reactions, variable oxidation states, and stability. In addition, these are environment friendly in nature and cost effective. However, they have some limitations to be used as electrode materials such as low electrical conductivity that causes less energy storage. To rectify these limitations, nanocomposites have been prepared as effective electrode materials to enhance the overall electrochemical performance. Mainly, transition metals and their composites with CPs have been reported in various forms of chemical compositions and morphological structures. These nanocomposites are synthesized by different techniques, such as chemical synthesis, in situ polymerization, electropolymerization, blending, hydrothermal, mechanical, template-assisted methods. In this chapter, we are addressing the CP and MO nanocomposite syntheses, characterizations, and applications for supercapacitors. Herein, the properties, synthetic methods, and characteristics for supercapacitor applications of various CP-M- and CP-MO-based nanocomposites have been discussed in detail with help of examples.