High performance of active carbon-based supercapacitor introduced with NiSO4 and CoSO4 redox active electrolytes in acid media

Abstract

The effects of incorporating NiSO4 and CoSO4 as redox additives into an H2SO4 acid medium to improve the functionality of a capacitor that is based on active carbon were studied using impedance spectroscopy, galvanostatic charge-discharge, and cyclic voltammetry. The power density (432 W kg−1 and 426 W kg−1), energy density (55.2 Wh kg−1 and 49.8 Wh kg−1), and specific capacitance (924 F g−1 and 842 F g−1) were achieved in electrolytes of NiSO4–H2SO4 and CoSO4–H2SO4, respectively, assuming a density of 1 A g−1, through diffusion-controlled redox reactions at the negative electrode.