Cathode of Zn-Ni Layered Double Hydroxide Nanosheet Arrays Wrapped with a Porous NiMoS_<i>x</i> Shell and Anode of 3D Hierarchical Nitrogen-Doped Carbon for High-Performance Asymmetric Supercapacitors

Abstract

The rational design and synthesis of multicomponent core@shell structures with fine morphology is a promising approach to develop electrode materials for advanced supercapacitors. In this study, Zn-Ni LDH@NiMoSx nanosheets with a hierarchical heterostructure are grown in situ on nickel foam through the hydrothermal routes, for the potential use as an integrated positive electrode material. The Zn-Ni LDH@NiMoSx shows a unique morphology and mesoporous feature with excellent synergistic effects between individual components. Compared to the single components of Zn-Ni LDH and NiMoSx, the Zn-Ni LDH@NiMoSx nanosheet arrays show better specific capacity (357.88 mA h g–1 at a current of 5 mA cm–2) and rate performance. Meanwhile, ZIF-8 derived 3D nanoporous N-doped carbon (ZPNC) material is used as an negative electrode material with high surface area (918.3 m2 g–1), excellent capacity (52.42 mA h g–1 at 2 mA cm–2), and rate performance (∼55% at 50 mA cm–2). The asymmetric supercapacitor device based on Zn-Ni LDH@NiMoSx and ZPNC electrodes exhibits a specific capacity of 73.18 mA h g–1 at 3.5 mA cm–2 and an excellent cycle lifespan of 90% after 6000 cycles. The device also demonstrates excellent energy density (58.54 W h kg–1) and very high power density (7397.34 W kg–1).