Synergistic effect of bimetal (Zn/Ni)–organic framework/reduced graphene oxide for high-performance supercapacitor

Abstract

Supercapacitors with the advantages of large capacitance, long cycle life and high energy density are prominent for innovation in energy storage components. Herein, Zn/Ni-MOF/rGO composites are successfully synthesized through a one-step solvothermal method. The MOF/rGO compounds exhibit mutually beneficial synergies in structure: rGO sheets prevent MOF microspheres from serious agglomeration, while MOF microspheres could be spacers for inhibiting the overlapping of rGO. When the mass of GO was 25 % of the mass of the metal salt, Zn/Ni-MOF microspheres are well-dispersed among cross-linked rGO sheets (GMOF-25). The GMOF-25 delivers a splendid specific capacitance of 1644 F/g at a current density of 1 A/g and acceptable stability (85.1 % of the capacitance retention rate after 3000 cycles). In addition, the GMOF-25//activated carbon asymmetric supercapacitor displays a high energy density of 47.4 Wh/kg at a power density of 825 W/kg. The synergistic effect has been proved to play a vital role in promoting the electrochemical performance of supercapacitors via XRD, Raman and FTIR. This work provides a research approach for the design and manufacture of high-performance supercapacitors.