Maximized Energy Density of RuO2//RuO2 Supercapacitors through Potential Dependence of Specific Capacitance

In this study, a stepwise cyclic voltammetry approach was proposed to clarify the potential dependence of specific capacitance for reduced graphene oxide and ruthenium oxide electrodes. Based on the relationship between specific capacitance and potential, the working voltage window and energy density of RuO2//RuO2 supercapacitors (SCs) were maximized by modulating the mass ratio. The working voltage window of RuO2//RuO2 with a mass ratio of 2.03 (close to optimum mass ratio m+/m-OPTM=2.04) was extended by about 188 % when compared to that calculated at a mass ratio of 0.56. The former was equivalent to a 304 % increase in energy density. In addition, the source of wasted potential window of electrodes on RuO2//RuO2 was investigated in an effort to design and produce better SCs.