Facile synthesis of novel Zn5Mo2O11·5H2O nanoflowers with excellent rate capability in supercapacitors

Abstract

Metal oxides are considered as promising pseudocapacitive materials with high theoretical capacitance. However, the low electric conductivity and low rate capability of metal oxides limit their practical applications in supercapacitors. Therefore, high rate capability electrode materials are highly desirable in energy storage system. In this work, a facile method has been demonstrated to synthesize novel Zn5Mo2O11·5H2O nanoflowers. Benefiting from the synergistic effects of nanoflower structure with abundant active sites and the hydrous feature with improved ion diffusion and electron transfer, the Zn5Mo2O11·5H2O nanoflowers electrode shows a capacitance of 347.3 F g−1 at a current density of 1.0 A g−1 and a state-of-the-art capacitance retention of ∼85.0% when the current density increases by 20 times (20.0 A g−1). The assembled asymmetric hybrid supercapacitor using the Zn5Mo2O11·5H2O nanoflowers electrode and active carbon electrode shows a maximum energy density of 26.7 Wh kg−1, a high power density of 15.0 kW kg−1 and a long cycling life (81.4% capacitance retention after 5000 cycles). This study sheds light on the synthesis and practical application of hydrous metal oxides with high rate capability in supercapacitors.