Sulfur-doped ZIF-derived Co3O4 flower-like microstructures for high stability supercapacitors

Abstract Sulfur-doped zeolitic imidazolate framework derived Co3O4 (S-ZIF-Co3O4) was prepared on Ni foam (NF) via the hydrothermal, annealing and sulfurization methods. S-ZIF-Co3O4 integrated the doping effect and structure advantage. Sulfur doping can increase Co3O4 electronic conductivity to decrease the electrochemical impedance and improve the rate capacity. The ZIF-derived flower-like microstructures consisting of 1D nanowires and 2D petal-like subunits can ensure the high electron transfer, porous diffusion pathways, sufficient active sites and structural integrity. The synergistic effect on the composition and space is beneficial for advanced electrochemical performance and cycling stability. The S-ZIF-Co3O4 electrode delivered superior specific capacity 178 mA h g−1 (1424 F g−1) at 1 A g−1and good cycling stability (81.5% capacitance retention after 8000 cycles at 3 A g−1). The assembled S-ZIF-Co3O4//active carbon (AC) device achieved a high energy density of 29.6 Wh kg−1 at 804 W kg−1.