3D self-supported nanopine forest-like Co3O4@CoMoO4 core–shell architectures for high-energy solid state supercapacitors

Abstract Herein, we develop a supercapacitor electrode composed of 3D self-supported Co3O4@CoMoO4 core–shell architectures directly grown on nickel foam. Co3O4 nanocones are grown vertically on the nickel foam as the core and CoMoO4 nanosheets are further engineered to immobilized on the surface of the nanocones as the shell. The unique architecture take advantage of a large interfacial area, numerous channels for rapid diffusion of electrolyte ions, fast electron transport and the high electrochemical activity from both the Co3O4 and CoMoO4. The electrode exhibits high specific capacitance of 1902 F g−1 at current density of 1 A g−1, good rate capability, and cycling stability with 99% capacitance retention after 5000 cycles. Solid-state asymmetric supercapacitor (Co3O4@CoMoO4//CNTs) and symmetric supercapacitor (Co3O4@CoMoO4//Co3O4@CoMoO4) are fabricated with excellent electrochemical performance. The asymmetric supercapacitor with a maximum voltage of 1.6 V has demonstrated a high energy density of 45.2 W h kg−1, a high power density of 6400 W kg−1 at 37.0 W h kg−1, and outstanding cyclic stability with the capacitance retention of 98.5% after 3000 cycles.