Anchoring Ni-MOF nanosheet on carbon cloth by zeolite imidazole framework derived ribbonlike Co3O4 as integrated composite cathodes for advanced hybrid supercapacitors

Abstract

Metal-organic frameworks (MOFs) and their derivatives as electrode materials for energy storage and conversion are intriguing. However, the in-situ uniformly and firmly growing metal-organic framework materials directly on conductive substrates is limited and still challenging. Herein, an effective strategy is presented by constructing a ribbonlike Co3O4 nanoarrays that derived from zeolite imidazole framework (ZIF) on carbon cloth as “fixed piles” for the in-situ solvothermal synthesis of Ni-MOF nanosheets. As a result, the Ni-MOF nanosheets closely distribute on the surface of the carbon cloth with fluffy structure, which favors exposure of more active sites and rapid diffusion of electrolyte ions. The as-fabricated integrated composite electrode (Co3O4@Ni-MOF) delivers a good specific capacitance of 1416 F/g at the current density of 1 A/g, superior to the individual Co3O4 (410 F/g) and Ni-MOF electrode (690 F/g). Moreover, the specific capacitance can be kept at 90% of its original value after 3000 cycles. Based on these advantages, a hybrid supercapacitor fabricated by the Co3O4@Ni-MOF electrode and activated carbon (AC) shows prominent energy density of 68.6 Wh kg−1 at the power density of 510 W kg−1, and excellent cycling stability (about 12% capacitance loss after 5000 charge-discharge cycles).