Construction of flower-like ZnCo2S4/ZnCo2O4 arrays on Ni foam for high-performance asymmetric supercapacitors

The high-energy density of supercapacitors is urgently needed. In this work, we develop a high energy density hierarchical ZnCo2S4/ZnCo2O4 electrode material with flower-like structure directly anchored on nickel foam by hydrothermal and ion exchange method. The as-prepared hierarchical arrays take advantage of ZnCo2S4 with high electroactive surface area, flower-like morphology with rapid channels for ion diffusion and electron transport. ZnCo2O4 possesses good stability and cooperativity with ZnCo2S4. Remarkably, the ZnCo2S4/ZnCo2O4 delivers a specific capacitance of 1057.78 F g−1 at the current density of 1 A g−1 in a three-electrode system. An asymmetric supercapacitor (ASC) was assembled with ZnCo2S4/ZnCo2O4 as positive electrode and carbon nanotubes (CNTs) as negative electrode, delivers a high energy density of 127.4 W h kg−1 at a power density of 2520 W kg−1 and a long cycle life (89% of capacity retention after 5000 cycles). The assembled ASC can work as a power source, which can drive the fan after being charged.