Polyaniline based Nanocomposites for Supercapacitor Applications

Abstract

The main objective of this thesis is to develop polyaniline-based nanocomposite active electrode materials with high specific capacitance as well as cyclic stability, for supercapacitor applications. Intrinsic polymers play a key role in supercapacitor application because of their high corrosion resistance, flexibility, and good adhesion. Polyaniline is considered among all conducting polymers to be a promising supercapacitor material due to its superior properties such as multiple redox behavior, simple processability, high conductivity, and easy morphological alignment. Despite being one of the best supercapacitor materials, polyaniline has some disadvantages including poor cyclic stability (~1000 cycles) and low energy density. Several strategies have been adopted in the literature to overcome these issues. One of the strategies to develop nanocomposites of polyaniline with metal oxides and carbon-based materials. These nanocomposites show unique morphologies along with improvement in the specific capacitance and cycle life. In this study, we have synthesized and evaluated the performance of several polyaniline-based nanocomposites. The first one we prepared was carbon-polyaniline nanocomposites namely, carbon nanotube-polyaniline, graphene oxide-polyaniline, and carbon nanotubes-graphene oxide-polyaniline. These nanocomposites benefit from the high specific surface area, high flexibility, and tensile strength of the carbon nanoforms, which improve the specific capacitance, allow high volumetric changes in the electrode material without degradation and as a result, provide better cyclic stability. The carbon nanoforms in polyaniline provide greater connectivity between the material domains. This enhanced connectivity and the resulting improved transport of charges could also be a key factor responsible for improving the cyclic stability of the polyaniline nanocomposite as a supercapacitor material. In any case, carbon-polyaniline nanocomposite supercapacitors show comparatively low specific capacitance...