Facile construction of MgCo2O4@CoFe layered double hydroxide core-shell nanocomposites on nickel foam for high-performance asymmetric supercapacitors

In this work, hierarchical MgCo2O4@CoFe layered double hydroxide (LDH) core-shell nanowire arrays on Ni foam (NF) are synthesized by facile hydrothermal and calcination methods. MgCo2O4/NF has been first synthesized via a hydrothermal reaction and annealing treatment and then utilized to prepare MgCo2O4@CoFe-LDH/NF core-shell nanocomposites via the second hydrothermal reaction. It is found that the MgCo2O4@CoFe-LDH/NF core-shell nanocomposite prepared from 3 h hydrothermal reaction (MC@CF-LDH-3) exhibits an excellent specific capacitance of 903.15 C g(-1) (2007 F g(-1)) at the current density of 1 A g(-1). Moreover, a high capacitance retention (80.2% maintained after 5000 cycles) and a low internal resistance (Rs) (0.75 Omega) can be acquired. Furthermore, an all-solid-state asymmetric supercapacitor (ASC) is assembled using MgCo2O4@CoFe-LDH/NF-3 as the positive electrode and activated carbon (AC) as the negative electrode. The as-fabricated MgCo2O4@CoFe-LDH/NF-3//AC ASC shows a high energy density of 60.82 Wh kg(-1) at 725 W kg(-1). Meanwhile, the MgCo2O4@CoFe-LDH/NF-3//AC ASC device possesses an excellent cycling stability of 93.6% retention of the initial capacitance after 5000 cycles and two ASC devices connected in series can light up a LED bulb for 8 min. Our results manifest that this hierarchical MgCo2O4@CoFe-LDH composite has huge potential application in energy storage devices.

Automated summary

Hierarchical MgCo2O4@CoFe-LDH core-shell nanowire arrays on Ni foam were synthesized via hydrothermal and calcination methods, showing excellent specific capacitance and cycling stability. These materials have great potential for application in energy storage devices.