Two-dimensional NiCo2O4nanosheet-coated three-dimensional graphene networks for high-rate, long-cycle-life supercapacitors

We report the synthesis of two-dimensional (2D) NiCo2O4 nanosheet-coated three-dimensional graphene network (3DGN), which is then used as an electrode for high-rate, long-cycle-life supercapacitors. Using the 3DGN and nanoporous nanosheets, an ultrahigh specific capacitance (2173 F g−1 at 6 A g−1), excellent rate capability (954 F g−1 at 200 A g−1) and superior long-term cycling performance (94% capacitance retention after 14 000 cycles at 100 A g−1) are achieved.