Excellent performance supercapacitors with the compounding of Ni(OH)2 and ZIF-67 derived Co–C–N nanosheets as flexible electrode materials

Abstract

Owing to the advantages of high theoretical capacity, low cost, and excellent chemical stability, Ni(OH)₂ is considered as a potential candidate for electrode materials of supercapacitors. However, its further applications are limited by its adverse surface chemical properties. In this paper, a composite material consisting of ZIF-67 derived Co–C–N nanosheets and Ni(OH)₂ was synthesized facilely on carbon cloth in situ, and based on the collective advantages of the various components, excellent electrochemical performance could be achieved when used as a flexible electrode material of supercapacitors. In detail, the as-obtained sample Ni(OH)₂/Co–C–N/CC exhibits an ultrahigh specific capacitance of 2100 F g⁻¹ at a current density of 1 A g⁻¹. Moreover, the further assembled asymmetric supercapacitor device exhibits a maximum energy density of 78.6 W h kg⁻¹ at a power density of 749.4 W kg⁻¹. Furthermore, the device also shows outstanding cycling stability with 90.2% capacitance retention after 5000 cycles of charge–discharge. Basically, the remarkable performance can be attributed to the well-developed structure, abundant active sites, complex beneficial components, and their intrinsic properties. Significantly, rational design can broaden the research directions of corresponding electrode materials.