Nanowire stacked bimetallic metal-organic frameworks for asymmetric supercapacitor

Abstract

Metal-organic frameworks (MOFs) have broad application prospects in the field of supercapacitors due to their unique construction and tunable pore size. However, maintaining high energy density under high power density is still a difficult problem to limit the application of supercapacitors. Herein, a simple, mild, and one-step solvothermal process was used to fabricate Ni-MOF crystals, which was a template for preparing flower-like NiCo-MOF-2 by in-situ etching methods. Interestingly, the “petals” of NiCo-MOF-2 are formed by stacking multiple nanowires, which can enhance richer active sites to promote charge transfer owing to the larger contact area between the electrolyte and the electrode material. Consequently, the NiCo-MOF-2 exhibits a larger specific capacity of 108.5 mAh g−1 at a current density of 0.5 A g−1 and the assembled asymmetric supercapacitor (NiCo-MOF-2//AC) delivers a stack energy density of 45.7 Wh kg−1 at a power density of 450.6 W kg−1 with excellent life span of 84.3% capacity retention after 6500 cycles.