Hierarchical zinc cobalt sulfide flowers grown on nickel foam as binder-free electrodes for high-performance asymmetric supercapacitors

Abstract

In this work, hierarchical zinc cobalt sulfide flowers on nickel foam (f-Zn0.76Co0.24S/Ni foam) are fabricated by a facile two-step hydrothermal method. The obtained f-Zn0.76Co0.24S/Ni foam are directly used as the binder-free electrodes for high-performance supercapacitors. The as-prepared f-Zn0.76Co0.24S/Ni foam exhibite a high specific capacitance of 1906 F g−1 at a current density of 1 A g−1 and good rate performance. The excellent electrochemical performance can be attributed to the unique interconnected flower structure, which provides a path for the rapid diffusion of electrolyte ions. Moreover, the f-Zn0.76Co0.24S/Ni foam//Fe2O3@rGO asymmetric supercapacitor is assembled. It can achieve a high energy density of 75.7 Wh kg−1 at a power density of 700.5 W kg−1 and display superior cycling stability with 86.7% retention after 8000 cycles.