Honeycomb-like NiCo2O4@Ni(OH)2 supported on 3D N−doped graphene/carbon nanotubes sponge as an high performance electrode for Supercapacitor

In order to increase the energy density of supercapacitor, a new kind electrode material with excellent structure and outstanding electrochemical performance is highly desired. In this article, a new type of three-dimensional (3D) nitrogen-doped single-wall carbon nanotubes (SWNTs)/graphene elastic sponge (TRGN−CNTs−S) with low density of 0.8 mg cm−3 has been successfully prepared by pyrolyzing SWNTs and GO coated commercial polyurethane (PU) sponge. In addition, high performance electrode of the honeycomb-like NiCo2O4@Ni(OH)2/TRGN-CNTs-S with core-shell structure has been successfully fabricated through hydrothermal method and then by annealing treatment and electrochemical deposition method, respectively. Benefited from 3D structural feature, the compressed NiCo2O4@Ni(OH)2/TRGN-CNTs-S electrode exhibits high gravimetric and volumetric capacitance of 1810 F g−1, 847.7 F cm−3 at 1 A g−1. The high rate performance and long-term stability was also obtained. Furthermore, an asymmetric supercapacitor using NiCo2O4@Ni(OH)2/TRGN-CNTs-S cathode and NGN/CNTs anode delivered high gravimetric and volumetric energy density of 54 W h kg−1 at 799.9 W kg−1 and 37 W h L−1 at 561.5 W L−1. In summary, an excellent electrochemical electrode with new elastic 3D SWNTs/graphene supports and binder free pseudocapacitive materials was introduced.