3D heterostructured cobalt oxide@layered double hydroxide core–shell networks on nickel foam for high-performance hybrid supercapacitor

Abstract

High performance of an electrode relies largely on scrupulous design of nanoarchitectures and smart hybridization of bespoke active materials. Here, a 3D heterostructured core–shell architecture was fabricated as a supercapacitor electrode, in which Co₃O₄ nanowire cores were grown on nickel foam prior to the in situ deposition of layered double hydroxide (LDH) nanosheet shells. Owing to the unique configuration and hybridization, the as-fabricated Co₃O₄@LDH core–shell electrode exhibited high capacities of 818.6 C g⁻¹ at 2 A g⁻¹ and 479.3 C g⁻¹ at 40 A g⁻¹ (3.2 C cm⁻² at 7.8 mA cm⁻² and 1.87 C cm⁻² at 156 mA cm⁻²), which were much higher than those of the individual components, namely, Co₃O₄ and LDH. A hybrid supercapacitor with Co₃O₄@LDH as the positive electrode and graphene nanosheets as the negative electrode yielded an energy density of 53.2 W h kg⁻¹ and a power density of 16.4 kW kg⁻¹, which outperformed devices reported in the literature; the device also exhibited long-term cycling stability and retained 71% of its initial capacity even after 10 000 cycles at 6 A g⁻¹. The rational design of the core–shell architecture may lead to the development of new strategies for fabricating promising electrode materials for electrochemical energy storage.