A redox additive electrolyte boosted supercapacitive energy density of wrinkled RGO sheets

Abstract

Redox additive (RA)-based electrolytes have emerged as a promising approach to enhance the performance of carbon-based supercapacitors (SCs) as they bestow the additional pseudocapacitance to carbon and enhance its energy density (Ed). The present study demonstrates the enhanced supercapacitive Ed of reduced graphene oxide (RGO) electrodes by employing an RA of 0.05 M K4[Fe(CN)6] (KFC) in 0.5 M K2SO4 (K2) electrolytes. To enhance the active surface area (confirmed by N2 absorption- desorption) with minor agglomeration (confirmed by morphological analysis) and less defective (confirmed by Raman analysis) wrinkled RGO sheets were synthesized through thermal reduction of GO. The RGO electrode obtained 3 times higher specific capacitance (CS) in K2+ KFC as compared to the K2 electrolyte. The assembled RGO-based symmetric aqueous device shows CS of 79.5 F/g and 66 mAh/g of specific capacity (CPS) at 5 mV/s with 36.8 Wh/kg Ed, 1.2 kW/kg of Pd at 15 mA, and 134 % capacitance retention over 5000 galvanostatic charge-discharge cycles in K2 + KFC electrolyte. The obtained results demonstrated the incorporation of a tiny amount of RA in supporting electrolytes can significantly enhance the electrochemical performance and pave the way for future advanced energy storage technology.