Growth of zinc oxide rods at 100 nm scale from electrohydrodynamically split and deposited nitrate precursor sol for use in electrochemical energy storage
摘要
The zinc oxide electrode was fabricated by electrohydrodynamic atomization of an aqueous zinc nitrate hexahydrate solution on a nickel foam substrate and subsequent calcination in situ at 350 ℃ in nitrogen environment. At a typical mass loading of 0.7 mg.cm−2, the near-vertical alignment of the cluster of cuboid-shaped rods with a height of several micrometers and other dimensions of 100 nm was observed forming over the inner wall of the nickel foam substrate. The nickel foam sheets, with the coating of active ZnO layer, when assembled in a two-electrode set-up with 2 M aqueous KOH as the electrolyte, the resulting specific capacitance, energy, and power densities at a current density of 1 mA.cm−2 (1.43 A.g−1) were found to be 629 F.g−1, 219.74 W.h.kg−1, and 2.31 kW.kg−1, respectively. After 5000 charge–discharge cycles, 85% of the capacitance could be retained. Further analysis of cyclic voltammetry (CV), galvanostatic charge discharge (GCD), and EIS data was performed to ascertain Faradaic and double-layer contributions over the charge–discharge cycle.