Balancing crystallinity and specific surface area of metal-organic framework derived nickel hydroxide for high-performance supercapacitor

Crystallinity and surface areas play important roles on the energy storage performances of electroactive materials. Herein, a Ni-based metal-organic framework (MCF-35) is employed as the template to fabricate hierarchical Ni(OH)2 for supercapacitor applications. By careful controlling of reaction time and pH of the reaction media, the crystallinity and surface areas of prepared Ni(OH)2 could be tuned and an optimizing structure with balanced crystalline and surface area could be obtained. Such a structure offers high electrochemical active sites and efficient pathways for ion migration and electron transportation. Thus, a remarkable and excellent capacity of 250.6 mA h g−1 (2255 F g−1) at a current density of 0.5 A g−1 is achieved. Meanwhile, using active carbon and the optimized Ni(OH)2 as electrodes, a hybrid supercapacitor is fabricated which exhibits an energy density of 42.54 Wh kg−1 at the power density of 370.8 W kg−1.