Effects of Low-Temperature Reduction Stage on Electrochemical Properties of Graphene Hydrogel Based Supercapacitors

Graphene hydrogels were synthesized by self-assemble method with two reduction stages at different temperatures and supercapacitors based on the hydrogel electrodes were packaged with Na2SO4 solution electrolyte. The structures were characterized by scanning electron microscopy and the electrochemical properties were investigated in a two-electrode system. The low-temperature reduction stage before heating reduction stage will bring the hydrogel a larger pore size, increases in specific capacitance and energy density. The graphene hydrogel electrodes with a low-temperature reduction stage has a pore size about10 mu m, larger than that of other hydrogels, a high specific capacitance of 184 F/g at the current density of 2A/g, and an energy density of 5.99 Wh/kg.