Interconnected network of zinc-cobalt layered double hydroxide stick onto rGO/nickel foam for high performance asymmetric supercapacitors

Herein, zinc cobalt layered double hydroxide (ZnCo-LDH) hybrid composites with different Zn/Co molar ratios are in-suit grown onto Ni foam by a simple and cost-effective hydrothermal approach. It is found that the Zn/Co molar ratios have an important influence on the morphology and electrochemical performance of the ZnCo-LDH composites. An interconnected nanowires structure and the highest specific capacitance were achieved when the Zn/Co molar ratio is 1: 2 (Zn1Co2-LDH).Moreover, interconnected Zn1Co2-LDH is further combined with reduced graphene oxide stuck onto Ni foam (Zn1Co2-LDH@rGO/NF) to improve its electrochemical properties. Benefiting from its unique structural feature and excellent electrical conductance ability, the as-prepared material exhibits an enhanced specific capacitance of 2142.0 F g−1 as supercapacitor electrode. Remarkably, the assembled asymmetric supercapacitor device based on Zn1Co2-LDH@rGO/NF and active carbon delivers a high specific capacitance (149.6 F g−1), high energy density (53.2 Wh kg−1), and excellent long cycling stability (90.9% capacitance retention after 6000 cycles at 3 A g−1), which holds huge potential for practical application in energy conversion and storage fields. [Display omitted] •ZnCo-LDH composites were grown on nickel foam with different Zn/Co molar ratios.•The influences of Zn/Co ratios on morphology and electrochemical performances were investigated.•Interconnected Zn1Co2-LDH@rGO/NF displays superior electrochemical properties.•Asymmetric supercapacitor device delivers high energy density and excellent cycling stability.