Polyaniline integration and interrogation on carbon nano-onions empowered supercapacitors

Abstract

The clean energy storage and fast delivery during the demand for sudden power applications encourage us to synthesize highly graphitic carbon nano-onions (CNOs) using a simple, one-step synthesis protocol. The as-synthesized CNOs demonstrate an excellent electrochemical property without employing any post-synthesis harsh chemical treatments and purifications. The integration of CNOs with the polyaniline (PANI) by the in-situ oxidative polymerization of the aniline monomer shows noticeable enhancement in the PANI's overall electrochemical performance. PANI/CNO heterostructure exhibits a maximum deliverable specific capacitance of 196 F g−1 at the current density of 1 A g−1. Notably, the energy and power densities also show enhancement for the heterostructure. In the hybrid heterostructure, CNO effectively improves the electronic conductivity, lessens the PANI fibers' agglomeration, and generates a larger active surface for the electrolytic ion interactions. Simultaneous contribution and synergistic effect from the CNO and the PANI lead to the co-existence of both electric double layer and pseudocapacitive specific capacitance in the nanocomposite. Favorable mesoporous structure with uneven surface contributed by incorporating CNOs results in enhanced wettability and shorter ion diffusion path in the PANI/CNO electrode. The successful integration of CNO into PANI augmented the capacitive performance of the device effectively.