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

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 Co ₃ O ₄ 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 Co ₃ O ₄ @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, Co ₃ O ₄ and LDH. A hybrid supercapacitor with Co ₃ O ₄ @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.