Hierarchical 3-dimensional CoMoO₄ nanoflakes on a macroporous electrically conductive network with superior electrochemical performance

Nanoscale cobalt molybdate (CoMoO₄) particles are fabricated hydrothermally on the surface and sidewall of three-dimensional nickel-coated silicon microchannel plates (also called macroporous electrically conductive network, MECN) as the active electrode in a miniature energy storage device. The relationships between the reaction time, morphology, formation mechanism of the CoMoO₄ nanostructure, and electrochemical performance are studied. After an optimal hydrothermal synthesis time of 2.5 h, the CoMoO₄ electrode has a capacity of 32.40 mA h g^-1 (492.48 μA h cm^-2) at constant current density of 1 A g^-1 and retention ratio of 85.98% after 5000 cycles. The large specific capacity 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, and enhances the utilization efficiency of the active materials. Furthermore, the weight and size of the device are reduced. By using the CoMoO₄/MECN electrode as the positive electrode and carbon/nickel foam (carbon/NF) as the negative electrode, the faradaic electrode was packaged by a CR2025 battery cell as the miniature hybrid device exhibits stable power characteristics (5000 cycle times with 71.82% retention). After charging each hybrid device for 10 s, three devices in series can power two 5 mm diameter light-emitting diodes (LED) efficiently.