WO3 nanoflowers with excellent pseudo-capacitive performance and the capacitance contribution analysis†
Pseudocapacitors have attracted more and more attention during the recent years because of their high capacitance and large energy density. As a traditional pseudocapacitive material, WO3 possesses high theoretical capacitance and good conductivity among various transition metal oxides. Herein, a nanoflower-like WO3 (NFL-WO3) electrode with perfect electrochemical performance is synthesized through a facile and effective electrodeposition method. The NFL-WO3 electrode after optimization exhibits a very high areal specific capacitance (Ca) of 658 mF cm−2, which is the highest one in pure WO3 materials to the best of our knowledge and a large gravimetric specific capacitance (Cg) of 196 F g−1 at a scan rate of 10 mV s−1. Our result demonstrates the excellent balance between Ca and Cg compared with other reported WO3 based materials. After experiencing 5000 cycles, 85% of its capacitance can still be retained. Based on the full analysis of cyclic voltammetry curves and Nyquist plots, the pseudocapacitance should be the dominate contribution to the total capacitance. In addition, it can be assembled into an asymmetric supercapacitor for powering small electronics (light-emitting diode sets and mobile phone). All of the above exhibit the potential application of the NLF-WO3 electrode in energy storage devices.