Engineering onion-like nanoporous CuCo2O4 hollow spheres derived from bimetal–organic frameworks for high-performance asymmetric supercapacitors

Abstract

Engineering complex hollow nanostructures of mixed transition metal oxides is necessary to respond to the increasing progress of modern electronics. As an interesting spinel mixed metal oxide, for the first time, we engineer onion-like nanoporous CuCo₂O₄ hollow spheres (ON-CCO) with a high surface area of 63 m² g⁻¹ and more than six thin shells. It is derived from bimetal–organic frameworks for high-performance asymmetric supercapacitors. The ON-CCO electrode exhibits excellent electrochemical performance including high reversibility, fast kinetics, low internal resistance, and an ultrahigh specific capacitance of 1700 F g⁻¹ with an excellent rate capability of 68% after increasing the current density by a factor of 50. Furthermore, the as-prepared ON-CCO//AC asymmetric supercapacitor delivers significant performance consisting of excellent cycle life (only 8.8% loss after 10 000 charge/discharge cycles), a maximum energy density of 48.75 W h kg⁻¹ and a power density of up to 37.5 kW kg⁻¹, which is superior to conventional supercapacitors and can compete with Ni–MH batteries. This remarkable performance attributed to the unique structural properties of the ON-CCO electrode holds great promise for the next-generation of high-performance portable electronics and electric vehicles.