Research on the High-Performance Electrochemical Energy Storage of a NiO@ZnO (NZO) Hybrid Based on Growth Time

Abstract

A NiO@ZnO (NZO) hybrid with different reaction times was successfully synthesized by a green hydrothermal method. After comparison, it was found that hydrothermal time had a great impact on specific capacitance. As a supercapacitor electrode of NZO-12h, it exhibited the maximum reversible specific capacitance of 985.0 F/g (3.94 F/cm2) at 5 mA/cm2 and 587.5 F/g (2.35 F/cm2) at 50 mA/cm2, as well as a high retention of 74.9% capacitance after 1500 cycles at 20 mA/cm2. Furthermore, the asymmetric electrode device with ZnO-12h and activated carbon (AC) as the positive and negative electrodes was successfully assembled. In addition, the device exhibited a specific capacitance of 85.7 F/g at 0.4 A/g. Moreover, the highest energy density of 27.13 Wh kg−1 was obtained at a power density of 321.42 W kg−1. These desirable electrochemical properties demonstrate that the NZO hybrid is a promising electrode material for a supercapacitor.

Special Issue Editorial: Functional Oxide Based Thin-Film Materials

“…Based on their obvious advantages, such as simple design, high-power density, a long cycling lifetime, and a short charge/discharge rate, supercapacitors have attracted much research interest in recent years. Zheng and co-workers in [10] have synthesized a NiO@ZnO (NZO) hybrid with different reaction times by a green hydrothermal method. A highest energy density of 27.13 Wh kg −1 can be achieved at a power density of 321.42 W kg −1 .…”