Two-dimensional NiCo2O4 nanosheet-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.