A flower-like Co/Ni bimetallic metal-organic framework based electrode material with superior performance in supercapacitors

In this paper, a Co/Ni bimetallic metal-organic framework (ZIF-67 @Ni-salicylate) is successfully synthesized through a two-step method. By increasing the reaction time to 48 h, the effect of the hydrothermal treatment on structure changes and electrochemical properties of ZIF-67 @Ni-salicylate is demonstrated. Electrochemical measurements show that the ZIF-67 @Ni-salicylate hydrothermal-treated with 48 h possesses a high specific capacitance of 1493 F g−1 at 1 A g−1 and simultaneously excellent cycle stability. Impressively, the capacitance retention rate can reach 86.8% even under a high current density of 40 A g−1, which is much better than that in previous reports. Furthermore, an asymmetric supercapacitor (ASC) is assembled and two ASCs connected in series can light up a red LED for more than 30 min as demonstrated by the current-time curve. Our work will be useful for the preparation of high-performance supercapacitor electrode materials.