Facile fabrication of ZIF-derived graphene-based 2D Zn/Co oxide hybrid for high-performance supercapacitors

Abstract Recently, rational design and synthesis of two-dimensional (2D) nanoflake based architectures have attracted great attention in energy storage systems due to their unique properties, such as high specific surface area, superior electrical and thermal conductivity. Zeolitic imidazolate frameworks (ZIFs) with 2D structure can be synthesized by a facile aqueous method and be used to obtain 2D metallic/binary metallic oxides. In this paper, graphene oxide and Zn2+ were added in the synthesis of Co-ZIF, and its derived oxide (ZnCoO-G) exhibits 2D nanosheet structure with well dispersed Co3O4 and ZnO nanoparticles after heat treatment. Compared with the derivatives without graphene oxide (ZnCoO) and Zn2+ (CoO-G), ZnCoO-G demonstrates the highest specific capacitance of 711.6 F g−1 at 1 A g−1 with a capacitance retention of 63.6% at 5 A g−1 after 1000 cycles. Also, an asymmetric supercapacitor (ASC) with ZnCoO-G and commercial active carbon as positive and negative electrodes has a maximum energy density of 18.7 W h kg−1 at a power density of 800 W kg−1.