An effective and rational strategy is developed for large-scale growth of firecracker-like Ni-substituted Co3O4 (NiCo2O4) nanosheets on beta-MnO2 nanowires (NWs) with robust adhesion as high-performance electrode for electrochemical capacitors. The NiCo2O4-MnO2 nanostructures display much higher specific capacitance (343 F g(-1) at current density of 0.5 A g(-1)), better rate capability (75.3% capacitance retention from 0.5 A g(-1) to 8 A g(-1)) and excellent cycle stability (5% capacitance loss after 3000 cycles) than Co3O4-MnO2 nanostructures. Moreover, an asymmetric supercapacitor based on NiCo2O4-MnO2 NWs as the positive electrode and activated graphenes (AG) as the negative electrode achieves an energy density of 9.4 Wh kg(-1) and a maximum power density of 2.5 kW kg(-1). These attractive findings suggest this novel core-shell nanostructure promising for electrochemical applications as an efficient super-capacitive electrode. (C) 2014 Elsevier B.V. All rights reserved.