CoS/Nitrogen-doped carbon composites derived from Zeolitic imidazolate frameworks-67 as advanced electrodes for supercapacitors

Abstract

Using ZIF-67 as precursor, CoS/Nitrogen-doped carbon (CoS/NC) composites are successfully prepared by applying chemical vapor deposition (CVD) treatment at three different curing temperatures. The results show that the optimal curing temperature is 700 °C, and CoS/NC-700 is a hollow cage-like polyhedron structure formed by the combination of CoS nanosheets and nitrogen doped carbon skeleton. The specific capacitance is 789 F g−1 at 1 A g−1 current density and a rate capacity of 80.2% under a 20 A g−1 of current density. The CoS/NC-700//AC capacitor has the highest energy density of 32.8 Wh kg−1 when the power density is 620.0 W kg−1 and the capacitor remains 89.2% of initial capacitance after 10,000 charge-discharge cycles at current density of 5 A g−1.