An Aqueous Asymmetric Supercapacitor Based on Activated Carbon and Tungsten Trioxide Nanowire Electrodes

An asymmetric supercapacitor (ASC) was assembled by using an activated carbon as positive electrode and WO₃ nanowire as negative electrode, and its electrical performances were tested in voltage windows ranging from 0 to 1.5 V. A high specific capacitance of 51 F•g⁻¹ could be achieved at the current density of 0.25 A•g⁻¹. Moreover, the ASC displays a good cycling stability with 86% of capacitance retention after 800 cycles, its energy density can be up to 11.9 Wh•kg⁻¹ at the power density of 210 W•kg⁻¹, and remains 7.7 Wh•kg⁻¹ at a power density of 1250 W• kg⁻¹. The excellent electrical performance is perhaps due to the crystal orientation of (001) planes for the WO₃ nanowire, which favors the rapid reaction between W(VI) and H⁺ cations. This aqueous asymmetric WO₃//AC supercapacitor is promising for practical applications due to its easy preparation of WO₃.