3D hierarchical Ni2+/Mn2+/Al3+ layered triple hydroxide @ nitrogen-doped graphene wrapped hybrids on nickel foam for supercapacitor applications

Nickel Foam as a substrate for morphology controllable synthesis of hierarchical nanocomposites with three-dimensional architecture is gaining substantial rank as effective energy materials for high-performance energy conservation and energy conversion devices. Herein, we report our findings in fabrication of 3D hierarchical, Ni2+/Mn2+/Al3+-layered triple hydroxide @ nitrogen-doped graphene wrapped hybrid on a nickel foam (marked as NMA-L@NG-NF) electrode, via a two-step hydrothermal method: primarily in situ hydrothermal growth of NiMnAl-LTH nanosheets over the surface of nickel foam, followed by secondary hydrothermal wrapping of NG graphene over the surface of NiMnAl-L@NF. The phase purity, structure, morphology and functionalities of the synthesized NMA-L@NG-NF hybrid electrodes were characterized comprehensively by XRD, FT-IR, Raman, XPS, EDS and SEM techniques. The results show that the obtained structure (NMA-L@NG-NF) possessed hierarchical flower-like configuration, which were self-assembled from LTH nanosheets and grafted successfully onto the framework of NF substrate during the hydrothermal process. Moreover, when tested as a binder-free electrode in a half cell three-electrode configuration, the NMA-L@NG-NF hybrid display significantly high specific capacity (452 mAh/g at 5 A/g), the excellent rate capability (75.8% at 20 A/g), the excellent cycling stability (91.4% of its initial capacity was retains at a current density of 10 A/g after 5000 cycles, with similar to 100% Coulombic efficiency) and very low R-CT value (0.34 omega before and 0.62 omega after 5000 charge discharge cycle from impedance measurements). It could be anticipated that the synthesized NMA-L@NG-NF hybrid is thus a highly promising electrode by virtue of their outstanding applications in high-performance energy storage and energy conversion devices.