Facile synthesis of cuboid Ni-MOF for high-performance supercapacitors

Abstract

Metal–organic frameworks (MOF) used directly in supercapacitors have attracted much attention for their special porous structure and potential high performance. Here, the Ni-MOF is fabricated by one-step facile hydrothermal method with a modification of mixed solution with DMF and water instead of pure DMF. After characterization, the Ni-MOF exhibits loosely stacked layer-cuboid structure with abundant mesoporous, which is beneficial for the charge transfer and ion transport for supercapacitors. In the three-electrode system, this Ni-MOF serving as working electrode shows remarkable specific capacitance of 804 Fg−1 at 1 Ag−1, excellent rate capacitance of 534 Fg−1 at 10 Ag−1, and with 302 Fg−1 retention after 5000 cycles, when measured in 2 M KOH electrolyte solution. To make a further research into the practical utility of the Ni-MOF, the Ni-MOF//AC asymmetrical supercapacitor device is assembled with the Ni-MOF and active carbon acted as positive and negative electrode materials, respectively. This device exhibits high specific energy of 31.5 Wh kg−1, at specific power of 800 W kg−1. All these results demonstrate that this Ni-MOF is a kind of promising electrode material for high-performance supercapacitors.