Synthesis of NiS and MOF-Derived Ni(OH) Composite Electrode Materials on Ni Foam for High-Performance Supercapacitors.

Honeycomb-like Ni(OH)/NiS/Ni foam (NF) was fabricated via a two-step hydrothermal process and subsequent alkalization. NiS with a honeycombed structure was in-situ synthesized on the NF surface by a hydrothermal process. MOF-derived Ni(OH) nanosheets were then successfully grown on the NiS/NF surface by a second hydrothermal process and alkaline treatment, and a large number of nanosheets were interconnected to form a typical honeycomb-like structure with a large specific surface area and porosity. As a binder-free electrode, the prepared honeycomb-like Ni(OH)/NiS/NF exhibited a high specific capacitance (2207 F·g at 1 A·g, 1929.7 F·g at 5 mV·s) and a remarkable rate capability and cycling stability, with 62.3% of the initial value (1 A·g) retained at 10 A·g and 90.4% of the initial value (first circle at 50 mV·s) retained after 5000 cycles. A hybrid supercapacitor (HSC) was assembled with Ni(OH)/NiS/NF as the positive electrode and activated carbon (AC) as the negative electrode and exhibited an outstanding energy density of 24.5 Wh·kg at the power density of 375 W·kg. These encouraging results render the electrode a potential candidate for energy storage.