MOF‐Derived Hollow Cage NixCo3−xO4 and Their Synergy with Graphene for Outstanding Supercapacitors. Issue 11 (11th January 2017)

• Record Type: Journal Article
• Authors: Jayakumar, Anjali; Antony, Rajini P.; Wang, Ronghua; Lee, Jong‐Min
• Is Part Of: Small. Volume 13:Issue 11(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-01-11
• Subjects: asymmetric supercapacitors -- energy storage -- graphene -- nickel cobalt mixed oxide -- optimization; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.201603102
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract : Highly optimized nickel cobalt mixed oxide has been derived from zeolite imidazole frameworks. While the pure cobalt oxide gives only 178.7 F g −1 as the specific capacitance at a current density of 1 A g −1, the optimized Ni:Co 1:1 has given an extremely high and unprecedented specific capacitance of 1931 F g −1 at a current density of 1 A g −1, with a capacitance retention of 69.5% after 5000 cycles in a three electrode test. This optimized Ni:Co 1:1 mixed oxide is further used to make a composite of nickel cobalt mixed oxide/graphene 3D hydrogel for enhancing the electrochemical performance by virtue of a continuous and porous graphene conductive network. The electrode made from GNi:Co 1:1 successfully achieves an even higher specific capacitance of 2870.8 F g −1 at 1 A g −1 and also shows a significant improvement in the cyclic stability with 81% capacitance retention after 5000 cycles. An asymmetric supercapacitor is also assembled using a pure graphene 3D hydrogel as the negative electrode and the GNi:Co 1:1 as the positive electrode. With a potential window of 1.5 V and binder free electrodes, the capacitor gives a high specific energy density of 50.2 Wh kg −1 at a high power density of 750 W kg −1 . Abstract : Highly optimized nickel cobalt mixed oxide is derived from zeolite imidazole framworks. A composite of nickel cobalt mixed oxide/graphene 3D‐hydrogel enhances the electrochemical performance by virtue of a continuous and porous graphene conductive network.