Three-Dimensionally Porous NiCo2O4 Nanoneedle Arrays for High Performance Supercapacitor

NiCo2O4 nanoneedle arrays (NiCo2O4 NNAs) on different substrates (carbon fabrics (C.F.) and nickel foam (N.F.)) were successfully synthesized by a facile hydrothermal process followed by calcinations process in air. The architectures were directly used as electrode materials for supercapacitors, which exhibited high specific capacitance, excellent rate capability, and remarkable electrochemical stability even at a high current density. The specific capacitance of NiCo2O4 NNAs/N.F. reached 655 F/g at 1 A/g, still remained 544 F/g at a high current density of 20 A/g, which were much larger than those of NiCo2O4 NNAs/C.F. (400 F/g at 1 A/g, 256 F/g at 20 A/g). Furthermore, NiCo2O4 NNs/N.F. displayed excellent rate performance of 83% retention compared with 64% retention for NiCo2O4 NNAs/C.F. Additionally, the capacitance still maintained 81% of the initial NiCo2O4 NNAs/N.F. The high performance demonstrated that the NiCo2O4 NNAs structures possess enormous potential applications in energy storage devices.