Construction of hierarchical porous NiCo2O4 films composed of nanowalls as cathode materials for high-performance supercapacitor

Hierarchical porous NiCo2O4 films composed of nanowalls on nickel foam are synthesized via a facile hydrothermal method. Besides the mesoporous walls, the NiCo2O4 nanowalls are interconnected with each other to form hierarchical porous structure. These unique porous structured films possess a high specific surface area. The supercapacitor performance of the hierarchical porous NiCo2O4 film is fully characterized. A high capacity of 130 mA h g−1 is achieved at 2 A g−1 with 97% capacity maintained after 2,000 cycles. Importantly, 75.6% of capacity is retained when the current density changes from 3 A g−1 to 36 A g−1. The superior electrochemical performance is mainly due to the unique hierarchical porous structure with large surface area as well as shorter diffusion length for ion and charge transport.