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

The present study successfully synthesized NiCo2S4 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 NiCo2S4 nanotubes by adjusting the heating time of hydrothermal reaction. The optimized NiCo2S4 @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 NiCo2S4 @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 coreshell structured NiCo2S4 @NiMn-LDH hybrid arrays have extraordinary application potential in the energy storage field. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The present study successfully synthesized a core-shell hybrid structure of NiCo2S4 nanotubes@NiMn-LDH nanosheets on Ni foam. The optimized NiCo2S4 @NiMn-LDH electrode exhibited high specific capacity and excellent cycling stability, making it promising for energy storage applications.