Fabrication of hierarchical NiCo2S4 nanotubes@NiMn-LDH nanosheets core-shell hybrid arrays on Ni foam for high-performance asymmetric supercapacitors

• Hierarchical NiCo 2 S 4 nanotubes@NiMn-LDH nanosheets core-shell hybrid arrays were synthesized on Ni foam. • The growth density of the NiMn-LDH nanosheets as the shell was adjusted by controlling the hydrothermal reaction time. • The assembled ASC device exhibited a maximum energy density of 53.1 W h kg -1 . The present study successfully synthesized NiCo 2 S 4 nanotubes@NiMn-LDH nanosheets core-shell hybrid structure on Ni foam through a controllable three-step facile hydrothermal method, the NiMn-layered double hydroxides (LDHs) nanosheets with unlike thicknesses adhere to the outer layer of NiCo 2 S 4 nanotubes by adjusting the heating time of hydrothermal reaction. The optimized NiCo 2 S 4 @NiMn-LDH electrode was able to transmit a high specific capacity of 822.64 C g −1 (4.36 C cm −2 ) at a high current density of 50 mA cm −2 , and maintained 92.7% of its initial specific capacity after 5000 cycles at a current density of 50 mA cm −2 when 2 M KOH was used as the electrolyte. Furthermore, an asymmetric supercapacitor (ASC) device fabricated with NiCo 2 S 4 @NiMn-LDH as the positive electrode and activated carbon (AC) as the negative electrode, and it achieved a maximal energy density of 53.10 W h kg −1 at a power density of 370.82 W kg −1 also maintained 94.3% retention of the initial specific capacitance after 10,000 cycles at a high current density of 20 mA cm −2 . With the excellent electrochemical properties, the as-prepared core-shell structured NiCo 2 S 4 @NiMn-LDH hybrid arrays have extraordinary application potential in the energy storage field.