Fabrication of 3D HierarchicalSphericalHoneycomb-Like Nd 2 O 3 /Co 3 O 4 /Graphene/Nickel Foam Composite Electrode Material for High-Performance Supercapacitors.

A 3D hierarchical spherical honeycomb-like composite electrode materialof neodymium oxide (NdO), cobalt tetraoxide (CoO), and reduced graphene oxide (rGO) on nickel foam (named as NdO/CoO/rGO/NF) were successfully fabricated by combining the hydrothermal synthesis method and the annealing process. Nickel foam with a three-dimensional spatial structure was used as the growth substrate without the use of any adhesives. The NdO/CoO/rGO/NF composite has outstanding electrochemical performance and can be used directly as an electrode material for supercapacitors (SCs). By taking advantage of the large specific surface area of the electrode material, it effectively slows down the volume expansion of the active material caused by repeated charging and discharging processes, improves the electrode performance in terms of electrical conductivity, and significantly shortens the electron and ion transport paths. At a 1 A/g current density, the specific capacitance reaches a maximum value of 3359.6 F/g. A specific capacitance of 440.4 F/g with a current density of 0.5A/g is still possible from the built symmetric SCs. The capacitance retention rate is still 95.7% after 30,000 cycles of testing at a high current density of 10 A/g, and the energy density is 88.1 Wh/kg at a power density of 300 W/kg. The outcomes of the experiment demonstrate the significant potential and opportunity for this composite material to be used as an electrode material for SCs.