Synthesis of Ag/NiO Honeycomb Structured Nanoarrays as the Electrode Material for High Performance Asymmetric Supercapacitor Devices.

Metallic silver nickel oxide honeycomb nanoarrays were synthesized via a surfactant-assisted hydrothermal route. The crystal structure of the Ag/NiO nanoarrays was confirmed by X-ray diffraction. X-ray photoelectron spectroscopy confirmed the valance state of the nickel, oxygen, and metallic silver. The morphological studies and energy dispersive X-ray spectroscopy revealed the honeycomb structured nanoarrays and the elemental distribution of the prepared sample, respectively. The three-electrode measurements showed that the Ag/NiO nanoarray is a suitable electrode material for supercapacitor applications, which delivers the maximum specific capacity of 824 C g at a specific current of 2.5 A g. An Ag/NiO positive electrode-based asymmetric device was fabricated and tested. The asymmetric device yielded a high specific cell capacity of 204 C g at a specific current of 2.5 A g as well as a maximum energy density of 63.75 W h kg at a power density of 2812.5 W kg. These results are comparable to those of (NiMH) metal hydride batteries.