Synergistic effects of CoS-decorated Ni-MOF with hierarchical structures for high-performance supercapacitor electrode materials

To further improve the electrochemical performance of supercapacitor, the construction of composite based electrode material was proved to be an effective strategy. Herein, CoS-decorated Ni-MOF composites with hierarchical structures and obvious synergistic effects were synthesized by one-step hydrothermal and subsequent electrodeposition route. Benefitting from the increased surface roughness with more exposed active sites, the hierarchical structure with high space utilization rate for rapid ion transport as well as the improved conductivity and entire robustness, the optimal composites exhibited an excellent specific capacitance (2167.5 F g-1 at 1 A g-1), outstanding rate performance (up to 70.1% even at 5 A g-1) and the good cycle stability (80.12% capacity retention after 3500 cycles). The corresponding assembled asymmetric supercapacitors could reach an energy density 92.18 Wh kg-1 when the power density of was 1626.71 W kg-1, which overwhelmed most other reported works. What is more, the capacity retention could maintain 73.34% even after 7000 cycles, indicating the excellent cycle stability. Overall, to our knowledge, this is the first report on a synergistic effect of a combination of Ni-MOF and CoS. The constructed composites exhibited great potential as promising candidates for high-performance energy storage devices.