Hierarchical CoMoO4@Co3O4 nanocomposites on an ordered macro-porous electrode plate as a multi-dimensional electrode in high-performance supercapacitors

Abstract

Nanoscale core–shell CoMoO₄@Co₃O₄ composite materials are fabricated by a multi-step hydrothermal process on the surface and side wall of an ordered macro-porous electrode plate (OMEP) as the active electrode in a high power density storage device. The morphology, formation mechanism of the CoMoO₄@Co₃O₄ nanostructure, and capacitor performance are systematically studied. The CoMoO₄@Co₃O₄/OMEP electrode has a capacity of 7.13 F cm⁻² (1168.0 F g⁻¹) at a constant current density of 0.6 A g⁻¹ and a retention ratio of 81.4% after 5000 cycles. The large specific capacitance and excellent rate capability can be attributed to the unique 3D ordered porous architecture which facilitates electron and ion transport, enlarges the liquid–solid interfacial area, prevents agglomeration of nanomaterials, and boosts the utilization efficiency of the active materials. Reconstruction on the surface of the porous structured substrate enhances the power density and cycling performance at large current densities. Using the CoMoO₄@Co₃O₄/OMEP electrode as the positive electrode and active carbon/nickel foam (AC/NF) as the negative electrode, the electrochemical electrode packaged in a CR2025 battery cell as a miniature hybrid device exhibits stable power characteristics (10 000 cycles with 91.7% retention at a current of 0.1 A). The device produces large instantaneous power that charging it for 10 s and using three devices in series can power four parallel LED arrays at a current of 0.152 A.