Viologen-based covalent organic polymers: Variation of morphology and evaluation of their ultra-long cycle supercapacitor performance

Abstract

Supercapacitor devices are increasingly significant in energy storage applications due to their excellent power density, quick charging/discharging capabilities, and long cycle ability. Due to their unique features, polymeric electrode materials have recently attracted attention. Here, we report the synthesis of two different viologen-based covalent organic polymers (COPs), COP-1 with a hollow sphere and COP-2 with hollow tube morphology, which were synthesized via the Zincke reaction by altering the polarity of the solvent. Their ultimate stability and π-extended conjugation rectify major bottlenecks of inhomogeneous aggregation brought on by structural deficiencies, restacking after repeated cycles, and inadequate connections during assembly observed on usual polymer electrodes. When employed as the dynamic electrode material in a three-electrode supercapacitor with 1 M H2SO4 as the aqueous electrolyte, COP-2 displayed remarkable electrochemical performance. Additionally, it showed astounding stability with 100 % capacitance retention after 50,000 cycles. In three electrode investigations, it also showed a specific capacitance of 604 F g−1 at a current density of 2 A g−1, and 404 F g−1 at 0.5 A g−1 for full cell studies. This research also offers a method for creating different morphology-driven COPs in high-performance supercapacitors.