Synergistic effect of bimetallic NiCo-MOF on foamed nickel for application in high-performance supercapacitors

Abstract

In this study, a series of bimetallic NiCo-MOFs with nanorod-like structures were successfully prepared on a foamed nickel skeleton. By adjusting the elemental ratio of nickel–cobalt, the synergistic effect between them was enhanced, thus improving the performance of the electrode material. Interestingly, it was found that with an increase in the Co²⁺ content the diameter of the nanorods becomes slender, which is conducive to the performance of supercapacitors. The performance is best when the nickel–cobalt ratio is 1 : 4, and the specific capacitance reaches 1894.3 F g⁻¹ when the current density is 1 A g⁻¹. At a current density of 10 A g⁻¹, the capacitance retention reaches 80.2% after 1000 GCD cycles. The button-type supercapacitor NiCo-MOF-2//AC assembled from it also has excellent electrochemical performance. When the current density was 5 A g⁻¹, the measured specific capacitance of the button supercapacitor was as high as 300.7 F g⁻¹. The stability of the device was tested at a current density of 10 A g⁻¹ and the capacitance retention was 87.9% after passing 5000 charge and discharge cycles. Therefore, the bimetallic NiCo-MOF prepared in this study has great application potential in supercapacitors.