Hierarchical design of core-shell structured Ni3S2/CoAl-LDH composites on rGO/Ni foam with enhanced electrochemical properties for asymmetric supercapacitor.

• Ni 3 S 2 /CoAl-LDH/rGO heterostructures were prepared via hydrothermal and electrodeposition methods. • The influences of different mass loading of Ni 3 S 2 on morphology and electrochemical performances are investigated. • The optimized electrode delivers excellent specific capacitance of 2457.5 F g−1. • The assembled asymmetric supercapacitor exhibits an outstanding energy density and a high cycling stability. [Display omitted] Three-dimensional hierarchical hybrid composites incorporating both CoAl-layered double hydroxide and Ni 3 S 2 grown onto the framework of reduced graphene oxide (rGO) on Ni foam were successfully fabricated by hydrothermal procedure combined with electrodeposition method (Ni 3 S 2 /CoAl-LDH/rGO). The Ni 3 S 2 nanoplates was anchored on the surface of the CoAl-LDH/rGO nanosheets, forming a cross linked core-shell structure. Electrochemical measurements demonstrate that the outer Ni 3 S 2 layer can significantly influence the morphology and electrochemical properties of the hybrid electrodes. Benefiting from its attractive structural feature and strong synergy of multiple components, excellent results were obtained in the composite with the optimal mass loading of Ni 3 S 2 layer, which exhibited an excellent specific capacitance of 2457.5 F g−1 at 1 A g−1 and a desirable cycling behavior of 90.0% retention over 5000 cycles. The assembled asymmetric supercapacitor using Ni 3 S 2 /CoAl-LDH/rGO as positive electrode and active carbon as negative electrode delivers a high energy density of 59.8 W h kg−1 at a power density of 402.8 W kg−1 and a good cycling property (91% capacitance retention after 8000 cycles). These encouraging results demonstrate that such hybrid nanostructure provides great potential as electrode material for the energy storage devices. [ABSTRACT FROM AUTHOR]