MOF assistance synthesis of nanoporous double-shelled CuCo2O4 hollow spheres for hybrid supercapacitors.

Design of complex hollow nanostructures of two or more transition metal oxides seems to be necessary to answer the demand for novel energy storage electrodes owning outstanding performance for advanced developments of modern electronics. Herein, we develop a metal-organic frameworks (MOFs) assistance self-templated method for the synthesis of double-shell CuCo2O4 hollow spheres as battery-type electrode material with a large surface area of 93 m2 g-1. This electrode material reveals excellent electrochemical performance with an ultrahigh specific capacity of 701 C g-1 at 2 A g-1. Additionally, remarkably high cycling performance is exhibited with maintaining more than 93.6% of the initial capacity after 6000 cycles. The assembly of the double-shell hollow spheres electrode with reduced graphene oxide (rGO) electrode in an asymmetric cell results in a high-performance supercapacitor with an energy density of 38.4 Wh kg-1 and a power density of 16 kW kg-1, that is remarkably higher than that of conventional supercapacitors and comparable with Ni-MH batteries. Additionally, we display that assembling two asymmetric devices in series could effectively power blue, green, and red LED indicators. The excellent electrochemical performance of the ZCCO electrode shows its high potential for the production of advanced energy storage devices.