A flexible and high energy density -hydrous RuO2 and keratin-derived renewable carbon composite-based asymmetric supercapacitor in redox-mediated electrolytes

Abstract

The present study exploits a chemical-free, low-cost, simple, scalable, and facile synthesis technique using an in-situ methodology to prepare composite electrodes. The as-synthesized composite is utilized as a hybrid electrode for supercapacitor application. The hydrous RuO2 and keratin fiber-derived carbon (ROKF-2) show excellent specific capacitance of 3542 F g−1 at 2 A g−1. However, true analysis reveals that the actual capacitance is 2556 F g−1. It focuses on delivering the actual performance of the hybrid device by eliminating the use of conventional equations. In symmetric assembly, the excellent device capacitance of 121 F g−1 at 1 A g-1 is achieved while maintaining its coulombic efficiency above 90% throughout the applied current. The double hybridization assembly shows the broadening of working potential with an outstanding energy density of 226 Wh kg−1 at 1000 W Kg−1. Upon introducing redox additives, the performance increases, suggesting their effective contribution to the charge storage process. In the presence of K3Fe(CN)6, the device delivers a remarkable rate capability of 50% till 5 A g−1, whereas, in the KI environment, the device efficiency gets enhanced ∼45%. The wire-shaped flexible device shows a specific capacitance of 142 mF cm−1 at a scan rate of 10 mV s−1 with an energy density of 0.03 mWh cm−1 at 33 W cm−1. The process approaches a chemical-free process for the composite synthesis, which can be utilized in various hybridization modes. The study eliminates the traditional equations to minimize the overestimated electrochemical performance. The prepared composites pave a new path in hybrid energy storage systems.