In situ growth of ZIF-8-derived ternary ZnO/ZnCo2O4/NiO for high performance asymmetric supercapacitors

Abstract

In this paper, the rational design and synthesis of ZIF-8-derived ternary ZnO/ZnCo₂O₄/NiO wrapped by nanosheets is introduced. Polyhedral ternary ZnO/ZnCo₂O₄/NiO composites surrounded by nanosheets with different compositions are successfully fabricated through in situ growth on ZIF-8 templates and subsequent thermal annealing in air. Electrochemical investigation reveals that when the molar ratio of nickel nitrate to cobalt nitrate is 1, the composite material is more outstanding, which shows a high specific capacitance of 1136.4 F g⁻¹ at 1 A g⁻¹ and excellent cycling stability of 86.54% after 5000 cycles. Moreover, the excellent performance of this material is also confirmed by assembling an asymmetric supercapacitor. The assembled hybrid device can reach a large potential range of 0–1.6 V and deliver a high energy density of 46.04 W h kg⁻¹ as well as the maximum power density of 7987.5 W kg⁻¹.