LAUSR

The synthesized ternary composite Co3O4/polyaniline/graphene delivered high capacitance of ~ 476 F g−1 at a current density of 2 A g−1, within the voltage window from − 0.8 to 0.8 V in three-electrode configuration. The symmetric device, fabricated using the composite material returned specific capacitance of ~ 37 F g−1 at a current density of 0.5 A g−1. Further, the effect of redox additive KI in electrolyte 1 M Na2SO4 was investigated in symmetric device configuration. The optimum results were obtained when 75 mmol KI was added with 1 M Na2SO4 electrolyte and capacitance increased more than two times, compared to the case while no redox additive was added in electrolyte and the maximum capacitance was found to be ~ 94 F g−1, at a current density 1 A g−1.