Facile In Situ Synthesis of Hierarchical Porous Ni/Ni(OH) 2 Hybrid Sponges with Excellent Electrochemical Energy‐Storage Performances for Supercapacitors

Herein, we report the in situ growth of single‐crystalline Ni(OH) 2 nanoflakes on a Ni support by using facile hydrothermal processes. The as‐prepared Ni/Ni(OH) 2 sponges were well‐characterized by using X‐ray diffraction (XRD), SEM, TEM, and X‐ray photoelectron spectroscopy (XPS) techniques. The results revealed that the nickel‐skeleton‐supported Ni(OH) 2 rope‐like aggregates were composed of numerous intercrossed single‐crystal Ni(OH) 2 flake‐like units. The Ni/Ni(OH) 2 hybrid sponges served as electrodes and displayed ultrahigh specific capacitance (SC=3247 F g −1 ) and excellent rate‐capability performance, likely owing to fast electron and ion transport, sufficient Faradic redox reaction, and robust structural integrity of the Ni/Ni(OH) 2 hybrid electrode. These results support the promising application of Ni(OH) 2 nanoflakes as advanced pseudocapacitor materials.