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.